Publications by authors named "Mark A Bullimore"

63 Publications

Pediatric Microbial Keratitis With Overnight Orthokeratology in Russia.

Eye Contact Lens 2021 07;47(7):420-425

University of Houston (M.A.B., K.R.), College of Optometry, Houston, TX; Morozovskaya City Children's Clinical Hospital (L.B.K., S.P.A., V.V.G.), Moscow, Russian Federation; and Doctor Lens Consulting, Ltd. (D.S.M., A.R.K., A.N.S.), Moscow, Russian Federation.

Objectives: To estimate the incidence of microbial keratitis in children wearing overnight orthokeratology lenses in Moscow, Russia.

Methods: To estimate the number of children wearing overnight orthokeratology lenses in 2018, 1,368 patient records from 13 Doctors Lens clinics were selected at random and extrapolated to the entire patient base. To identify cases of microbial keratitis, all episodes of infiltrative keratitis from Morozovskaya City Children's Clinical Hospital in 2018 were recorded and adjudicated by three experienced ophthalmologists. Incidence was calculated as the number of cases divided by the estimated number of wearers.

Results: There were 23,049 overnight orthokeratology fits between 2010 and 2018. Among the 1,368 records surveyed, 1,078 (79%) were younger than 18 years at initial fitting. Based on a 7% or 10% annual discontinuation rate, the estimated number of children wearing lenses in 2018 was 10,307 or 9,422, respectively. During 2018, there were 139 cases of corneal infiltrative keratitis in children and 45 were adjudicated as microbial keratitis (32%). Of these, 20 cases were associated with contact lens wear (44%): 15 soft lens wearers (33%) and 5 overnight orthokeratology wearers (11%). Based on the 5 cases and assuming a 7% or 10% discontinuation rate, the annual incidence is 4.9 (95% confidence interval[CI]: 2.1-11.4) or 5.3 (95% CI: 2.3-12.4) per 10,000 patient years.

Conclusion: The incidence of microbial keratitis in children wearing overnight orthokeratology is lower than a previous United States study and similar to rates associated with use of daily wear soft contact lenses.
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http://dx.doi.org/10.1097/ICL.0000000000000801DOI Listing
July 2021

The Risks and Benefits of Myopia Control.

Ophthalmology 2021 May 4. Epub 2021 May 4.

Department of Ophthalmology, Children's University Hospital, Dublin, Ireland; Centre for Eye Research Ireland, School of Physics, Clinical and Optometric Sciences, Technological University Dublin, Dublin, Ireland.

Purpose: The prevalence of myopia is increasing around the world, stimulating interest in methods to slow its progression. The primary justification for slowing myopia progression is to reduce the risk of vision loss through sight-threatening ocular pathologic features in later life. The article analyzes whether the potential benefits of slowing myopia progression by 1 diopter (D) justify the potential risks associated with treatments.

Methods: First, the known risks associated with various methods of myopia control are summarized, with emphasis on contact lens wear. Based on available data, the risk of visual impairment and predicted years of visual impairment are estimated for a range of incidence levels. Next, the increased risk of potentially sight-threatening conditions associated with different levels of myopia are reviewed. Finally, a model of the risk of visual impairment as a function of myopia level is developed, and the years of visual impairment associated with various levels of myopia and the years of visual impairment that could be prevented with achievable levels of myopia control are estimated.

Results: Assuming an incidence of microbial keratitis between 1 and 25 per 10 000 patient-years and that 15% of cases result in vision loss leads to the conclusion that between 38 and 945 patients need to be exposed to 5 years of wear to produce 5 years of vision loss. Each additional 1 D of myopia is associated with a 58%, 20%, 21%, and 30% increase in the risk of myopic maculopathy, open-angle glaucoma, posterior subcapsular cataract, and retinal detachment, respectively. The predicted mean years of visual impairment ranges from 4.42 in a person with myopia of -3 D to 9.56 in a person with myopia of -8 D, and a 1-D reduction would lower these by 0.74 and 1.21 years, respectively.

Conclusions: The potential benefits of myopia control outweigh the risks: the number needed to treat to prevent 5 years of visual impairment is between 4.1 and 6.8, whereas fewer than 1 in 38 will experience a loss of vision as a result of myopia control.
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http://dx.doi.org/10.1016/j.ophtha.2021.04.032DOI Listing
May 2021

Axial length targets for myopia control.

Ophthalmic Physiol Opt 2021 05 5;41(3):523-531. Epub 2021 May 5.

College of Optometry, University of Houston, Houston, USA.

Purpose: Both emmetropic and myopic eyes elongate throughout childhood. The goals of this study were to compare axial elongation among untreated progressing myopes, progressing myopes treated with a myopia control contact lens and emmetropes, in order to place axial elongation in the context of normal eye growth in emmetropic children, and to consider whether normal physiological eye growth places limits on what might be achieved with myopia control.

Methods: Axial elongation data were taken from the 3-year randomised clinical trial of a myopia control dual-focus (MiSight® 1 day) contact lens. These were compared with data for myopic and emmetropic children in two large cohort studies: the Orinda Longitudinal Study of Myopia (OLSM) and the Singapore Cohort Study of the Risk Factors for Myopia (SCORM). Each study's published equations were used to calculate annual axial elongation. Four virtual cohorts-myopic and emmetropic for each model-were created, each with the same age distribution as the MiSight clinical trial subjects and the predicted cumulative elongation calculated at years 1, 2 and 3 for myopes and emmetropes using both the OLSM and SCORM models.

Results: The untreated control myopes in the MiSight clinical trial showed mean axial elongation over 3 years (0.62 mm) similar to the virtual cohorts based on the OLSM (0.70 mm) and SCORM (0.65 mm) models. The predicted 3-year axial elongation for the virtual cohorts of emmetropes was 0.24 mm for both the OLSM and SCORM models-similar to the mean 3-year elongation in MiSight-treated myopes (0.30 mm).

Conclusions: The 3-year elongation in MiSight-treated myopes approached that of virtual cohorts of emmetropes with the same age distribution. It is hypothesised that myopic axial elongation is superimposed on an underlying physiological axial elongation observed in emmetropic eyes, which reflects increases in body stature. We speculate that optically based myopia control treatments may minimise the myopic axial elongation but retain the underlying physiological elongation observed in emmetropic eyes.
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http://dx.doi.org/10.1111/opo.12812DOI Listing
May 2021

CLEAR - Contact lens optics.

Cont Lens Anterior Eye 2021 Apr 25;44(2):220-239. Epub 2021 Mar 25.

Eurolens Research, Division of Pharmacy and Optometry, University of Manchester, UK.

The most fundamental aspect of a contact lens is its optics; the manner in which the refraction of light is managed to optimise vision to the clinical benefit of the lens wearer. This report presents contemporary information on the optical structure of the eye and the optical models employed to understand the correction of refractive error. The design, measurement and clinical assessment of spherical, aspheric, toric, multifocal and myopia control contact lenses are described. The complexity and variety of multifocal lenses is recognised and detailed information is provided for alternating, simultaneous, diffractive, annular, aspheric and extended depth of field lens designs. In terms of clinical assessment, a contemporary review is provided for the measurement of: visual acuity, contrast sensitivity, through focus curves, reading performance, peripheral refraction, toric displacement realignment and patient reported outcomes. Overall, the paper aims to serve as a resource for the prescribing clinician, who can optimise contact lens corrections for patients by building on the optical rationale of these devices; and also highlights future opportunities for research innovation.
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http://dx.doi.org/10.1016/j.clae.2021.02.005DOI Listing
April 2021

Progression of myopia in children and teenagers: a nationwide longitudinal study.

Br J Ophthalmol 2021 Mar 12. Epub 2021 Mar 12.

Ophthalmology, CHU Poitiers, Poitiers, France

Background: Data on myopia prevalence and progression in European children are sparse. The aim of this work was to evaluate the progression of myopia in children and teenagers in a large prospective study.

Methods: A prospective study involving a nationwide cohort. Myopia was defined as a spherical equivalent (SE) of ≤ -0.50 diopters (D). Data on refractive error, gender and age were collected in 696 optical centres in France between 2013 and 2019, including 136 333 children (4-17 years old) in the analysis.Progression of myopia was assessed between the first visit and the last visit over up to 6.5 years.

Results: Mean age was 11.3±3.8 years (55.0% of female). The proportion of children progressing more than -0.50 D per year was higher in age groups 7-9 years and 10-12 years and in children with SE ≤ -4.00 D at first visit, representing 33.1%, 29.4% and 30.0% of these groups, respectively. In multivariate analysis, progression during the first 11-24 months was higher in the 7-9 and 10-12 age groups (-0.43 D and -0.42 D, respectively), for higher SE at baseline (at least -0.33 D for SE ≤ -1 D) and for girls (-0.35 D).

Conclusion: This is the first French epidemiological study to investigate myopia progression in a large-scale cohort of children. Sex, age groups and myopia severity are associated with differing rates of progression.
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http://dx.doi.org/10.1136/bjophthalmol-2020-318256DOI Listing
March 2021

Efficacy in myopia control.

Prog Retin Eye Res 2020 Nov 27:100923. Epub 2020 Nov 27.

University of Houston, USA.

There is rapidly expanding interest in interventions to slow myopia progression in children and teenagers, with the intent of reducing risk of myopia-associated complications later in life. Despite many publications dedicated to the topic, little attention has been devoted to understanding 'efficacy' in myopia control and its application. Treatment effect has been expressed in multiple ways, making comparison between therapies and prognosis for an individual patient difficult. Available efficacy data are generally limited to two to three years making long-term treatment effect uncertain. From an evidence-based perspective, efficacy projection should be conservative and not extend beyond that which has been empirically established. Using this principle, review of the literature, data from our own clinical studies, assessment of demonstrated myopia control treatments and allowance for the limitations and context of available data, we arrive at the following important interpretations: (i) axial elongation is the preferred endpoint for assessing myopic progression; (ii) there is insufficient evidence to suggest that faster progressors, or younger myopes, derive greater benefit from treatment; (iii) the initial rate of reduction of axial elongation by myopia control treatments is not sustained; (iv) consequently, using percentage reduction in progression as an index to describe treatment effect can be very misleading and (v) cumulative absolute reduction in axial elongation (CARE) emerges as a preferred efficacy metric; (vi) maximum CARE that has been measured for existing myopia control treatments is 0.44 mm (which equates to about 1 D); (vii) there is no apparent superior method of treatment, although commonly prescribed therapies such as 0.01% atropine and progressive addition spectacles lenses have not consistently provided clinically important effects; (viii) while different treatments have shown divergent efficacy in the first year, they have shown only small differences after this; (ix) rebound should be assumed until proven otherwise; (x) an illusion of inflated efficacy is created by measurement error in refraction, sample bias in only treating 'measured' fast progressors and regression to the mean; (xi) decision to treat should be based on age of onset (or refraction at a given age), not past progression; (xii) the decreased risk of complications later in life provided by even modest reductions in progression suggest treatment is advised for all young myopes and, because of limitations of available interventions, should be aggressive.
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http://dx.doi.org/10.1016/j.preteyeres.2020.100923DOI Listing
November 2020

Visual Demand and Acuity Reserve of Chinese versus English Newspapers.

Optom Vis Sci 2020 Oct;97(10):865-870

College of Optometry, University of Houston, Houston, Texas.

Significance: This study suggests that Chinese newspaper characters are more legible than English newspaper letters. Characters in Chinese newspapers have higher acuity reserve than English newspapers.

Purpose: The purpose of this study was to evaluate visual demand and acuity reserve for Chinese newspapers in comparison with published data on U.S. newspapers.

Methods: The test distances for visual acuity in Chinese clinical studies were reviewed systematically. Characters from different sections of newspapers printed in simplified Chinese were evaluated. The character height, frequency, and visual demand and acuity reserve of each newspaper section were determined for Chinese characters of the six different levels of complexity.

Results: More than 70% of Chinese clinical studies measure near visual acuity at either 33 or 40 cm. The height of Chinese characters ranged from 1.95 to 3.28 mm across different sections of five newspapers compared with 1.0 to 2.0 mm for English letters. The frequency of Chinese characters from least to most complex ranged from 7 to 34% across 12 sections of one Chinese newspaper. The angular threshold across the six complexity levels of Chinese characters ranged from 4.62 to 5.93 arcmin (0.54 to 0.69 mm at 40-cm reading distance) with a weighted angular threshold of 5.18 arcmin compared with 3.37 arcmin (0.39 mm) for the English letters. For Chinese newspapers, at 40-cm reading distance, the acuity reserve for the smallest and largest median size was 3.55 and 4.61, respectively.

Conclusions: Chinese characters are larger than English characters in all newspaper sections newspapers by a factor of 1.60 to 2.34. Given that Chinese characters need to be 1.54 times larger than English letters to provide the same acuity reserve, on average, Chinese newspapers are more legible than U.S. English newspapers.
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http://dx.doi.org/10.1097/OPX.0000000000001585DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7592886PMC
October 2020

Letter from America.

Ophthalmic Physiol Opt 2020 Nov 5;40(6):708-709. Epub 2020 Oct 5.

University of California, Berkeley, USA.

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http://dx.doi.org/10.1111/opo.12740DOI Listing
November 2020

Comment on: 'Cochrane corner: Atropine: an ancient remedy for a twenty-first century problem?'

Eye (Lond) 2020 Sep 2. Epub 2020 Sep 2.

Johnson & Johnson Vision, Jacksonville, FL, USA.

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http://dx.doi.org/10.1038/s41433-020-01165-7DOI Listing
September 2020

Myopia Control 2020: Where are we and where are we heading?

Ophthalmic Physiol Opt 2020 05;40(3):254-270

College of Optometry, University of Houston, Houston, USA.

Purpose: This review arms practitioners with the evidence-based information they need to fully manage myopia.

Recent Findings: The recent peer-reviewed literature is critically evaluated to provide a comprehensive analysis of the safety and efficacy of behavioural, optical and pharmaceutical myopia management. Importantly, the paper addresses not only who to treat, but how to treat them, and when to stop or modify treatments. Finally, the paper discusses expectations for treatment and why slowing myopia by even 1 dioptre improves long term health outcomes.

Summary: The management of an individual child should be underpinned by the evidence-based literature and clinicians must stay alert to ongoing myopia research that will undoubtedly result in an evolution of the standard of care for the myopic and pre-myopic child.
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http://dx.doi.org/10.1111/opo.12686DOI Listing
May 2020

Overnight orthokeratology.

Cont Lens Anterior Eye 2020 08 22;43(4):322-332. Epub 2020 Apr 22.

University of Houston, College of Optometry, 4901 Calhoun Rd., Houston, TX, 77204, United States; Paragon Vision Sciences, 2120 West Guadalupe Road, Suite 112, Gilbert, AZ, 85233, United States. Electronic address:

Overnight orthokeratology lenses are approved in countries all over the world for the temporary reduction in myopia, and recently, one lens design has received regulatory approval for myopia control in Europe. The modern orthokeratology lens has a substantial history from its origins of attempting to flatten the corneal curvature with a spherical rigid contact lens to sophisticated gas permeable lenses, designed to reshape the cornea. These lenses are predominantly prescribed for children to slow myopia progression and limit axial elongation of the eye. This article reviews the peer-reviewed literature on the efficacy of orthokeratology for myopia control, sustainability after treatment is discontinued, and the safety concerns of overnight contact lens wear. Future avenues of research are discussed.
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http://dx.doi.org/10.1016/j.clae.2020.03.018DOI Listing
August 2020

Comparison of the iLUX and the LipiFlow for the Treatment of Meibomian Gland Dysfunction and Symptoms: A Randomized Clinical Trial.

Clin Ophthalmol 2020 12;14:405-418. Epub 2020 Feb 12.

University of Houston, College of Optometry, Houston, TX 77204, USA.

Purpose: To compare the effects of eyelid treatment with the iLUX MGD Treatment System and the LipiFlow Thermal Pulsation System on objective and subjective parameters of meibomian gland function and symptoms.

Patients And Methods: In this randomized, open-label, controlled, multicenter clinical trial, both eyes of 142 patients aged ≥18 years with Ocular Surface Disease Index (OSDI) scores ≥23, total meibomian gland scores (MGS) ≤12 in the lower eyelid of each eye, and tear break-up time (TBUT) <10 s were randomized 1:1 to iLUX or LipiFlow treatment, with stratification by test center. The primary effectiveness endpoints were changes in total MGS (masked) and TBUT from baseline to 4 weeks. The secondary effectiveness endpoint was changed in OSDI score from baseline to 4 weeks.

Results: Both devices significantly improved effectiveness outcomes, with no differences between the two devices. At the 4-week visit, mean MGS, TBUT, and OSDI scores improved at least 16.9 ± 11.5, 2.6 ± 3.2 s, and 28.0 ± 22.8, respectively, across treatment groups and treated eyes. Four device/procedure-related events occurred in the iLUX group, compared with none in the LipiFlow group, but there were no device-related adverse events that involved changes in lid margins, eyelids, or lash integrity. Corneal staining, intraocular pressure, and visual acuity did not differ in the two groups.

Conclusion: Both treatments produced significant improvements in meibomian gland function and symptoms. For all effectiveness measures, there were no statistically significant differences between the two treatments.
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http://dx.doi.org/10.2147/OPTH.S234008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7024784PMC
February 2020

Myopia Control: Why Each Diopter Matters.

Optom Vis Sci 2019 06;96(6):463-465

Johnson & Johnson Visioncare, Inc., Jacksonville, Florida

Significance: Reducing the incidence or prevalence of any disease by 40% is of huge public health significance. Slowing myopia by 1 diopter may do just that for myopic maculopathy-the most common and serious sight-threatening complication of myopia. There is a growing interest in slowing the progression of myopia due to its increasing prevalence around the world, the sight-threatening consequences of higher levels of myopia, and the growing evidence-based literature supporting a variety of therapies for its control. We apply data from five large population-based studies of the prevalence of myopic maculopathy on 21,000 patients. We show that a 1-diopter increase in myopia is associated with a 67% increase in the prevalence of myopic maculopathy. Restated, slowing myopia by 1 diopter should reduce the likelihood of a patient developing myopic maculopathy by 40%. Furthermore, this treatment benefit accrues regardless of the level of myopia. Thus, while the overall risk of myopic maculopathy is higher in a -6-diopter myope than in a -3-diopter myope, slowing their myopic progression by 1 diopter during childhood should lower the risk by 40% in both.
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http://dx.doi.org/10.1097/OPX.0000000000001367DOI Listing
June 2019

An Evaluation of the IOLMaster 700.

Eye Contact Lens 2019 Mar;45(2):117-123

Southern California College of Optometry (M.A.B.), Marshall B. Ketchum University, Fullerton, CA; College of Optometry (M.A.B.), The University of Houston, Houston, TX; Slade and Baker Vision Center (S.S.), Houston, TX; and Carl Zeiss Meditec (P.Y., T.O.), Dublin, CA.

Objectives: To evaluate the repeatability and reproducibility of the Carl Zeiss Meditec IOLMaster 700, which uses swept-source optical coherence tomography technology, along with its agreement with the IOLMaster 500 and Lenstar LS 900.

Methods: In a clinical practice, complete measurements were taken on one eye of 100 subjects: 51 with cataracts and 49 with clear lenses. Three sets of measurements were taken by 3 operators with three different IOLMaster 700 units, and one operator took 3 measurements with the IOLMaster 500 and the Lenstar. A random-effects model of analysis of variance was used to estimate the repeatability and reproducibility. The 95% limits of agreement (95% LoA) were calculated for all comparisons.

Results: Comparing the IOLMaster 700 and IOLMaster 500 in cataract patients, 95% LoA were -0.01 to +0.06 mm for axial length, -0.44 to +0.27 D for corneal power, and -0.18 to +0.17 mm for anterior chamber depth. Comparing the IOLMaster 700 and Lenstar for corneal thickness and lens thickness yielded 95% LoA of -4 to +13 μm and -0.26 to +0.41 mm, respectively. The repeatability and reproducibility limits for the IOLMaster 700 were ±0.014 and ±0.023 mm for axial length; ±0.26 and ±0.27 D for corneal power; ±7 and ±11 μm for corneal thickness; ±0.02 and ±0.02 mm for anterior chamber depth; and ±0.02 and ±0.05 mm for lens thickness, respectively.

Conclusions: There was good agreement between the IOLMaster 700 and comparator instruments and superior or equivalent precision. Some differences were noted, but not considered clinically meaningful.
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http://dx.doi.org/10.1097/ICL.0000000000000552DOI Listing
March 2019

Low-Dose Atropine for Myopia Control: Considering All the Data.

JAMA Ophthalmol 2018 03;136(3):303

College of Optometry, University of Houston, Houston, Texas.

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http://dx.doi.org/10.1001/jamaophthalmol.2017.6638DOI Listing
March 2018

The Safety of Soft Contact Lenses in Children.

Authors:
Mark A Bullimore

Optom Vis Sci 2017 06;94(6):638-646

*MCOptom, PhD, FAAO University of Houston College of Optometry (MAB), Houston, Texas.

Purpose: There is increasing interest in fitting children with soft contact lenses. This review collates data from a range of studies to estimate the incidence of complications, specifically corneal infiltrative events and microbial keratitis, in patients under the age of 18 years.

Methods: Peer-review papers were identified using PubMed and the Web of Science. A broad range of studies are summarized including large-scale epidemiological studies of contact lens-related complications, hospital-based case series, long- and short-term prospective studies, and multicenter retrospective studies.

Results: Nine prospective studies representing 1800 patient years of wear in 7- to 19-year-olds include safety outcomes. In three large prospective studies representing between 159 and 723 patient years of soft contact lens wear in patients 8 to 14 years, the incidence of corneal infiltrative events is up to 136 per 10,000 years. Data from a large retrospective study show similar rates of corneal infiltrative events: 97 per 10,000 years in 8- to 12-year-olds (based on 411 patient years of wear) and 335 per 10,000 years in 13- to 17-year-olds (based on 1372 patient years of wear). None of the prospective studies report any cases of microbial keratitis. Five clinical studies where safety data are not reported constitute a further 493 patient years. One retrospective study found no cases of microbial keratitis occurred in 8- to 12-year-olds (411 patient years) and an incidence of 15 per 10,000 patient years in 13- to 17-year-olds (1372 patient years)-no higher than the incidence of microbial keratitis in adults wearing soft contact lenses on an overnight basis.

Conclusions: The overall picture is that the incidence of corneal infiltrative events in children is no higher than in adults, and in the youngest age range of 8 to 11 years, it may be markedly lower.
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http://dx.doi.org/10.1097/OPX.0000000000001078DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5457812PMC
June 2017

The Effect of Age, Accommodation, and Refractive Error on the Adult Human Eye.

Optom Vis Sci 2016 Jan;93(1):3-11

*OD, PhD, FAAO †MCOptom, PhD, FAAO ‡PhD SUNY College of Optometry, New York, New York (KR); University of Houston College of Optometry, Houston, Texas (MAB); and The Ohio State University College of Optometry, Columbus, Ohio (LTS, KZ).

Purpose: To quantify changes in ocular dimensions associated with age, refractive error, and accommodative response, in vivo, in 30- to 50-year-old human subjects.

Methods: The right eyes of 91 adults were examined using ultrasonography, phakometry, keratometry, pachymetry, interferometry, anterior segment optical coherence tomography, and high-resolution magnetic resonance imaging. Accommodation was measured subjectively with a push-up test and objectively using open-field autorefraction. Regression analyses were used to assess differences in ocular parameters with age, refractive error, and accommodation.

Results: With age, crystalline lens thickness increased (0.03 mm/yr), anterior lens curvature steepened (0.11 mm/yr), anterior chamber depth decreased (0.02 mm/yr), and lens equivalent refractive index decreased (0.001/yr) (all p < 0.01). With increasing myopia, there were significant increases in axial length (0.37 mm/D), vitreous chamber depth (0.34 mm/D), vitreous chamber height (0.09 mm/D), and ciliary muscle ring diameter (0.10 mm/D) (all p < 0.05). Increasing myopia was also associated with steepening of both the cornea (0.16 mm/D) and anterior lens surface (0.011 mm/D) (both p < 0.04). With accommodation, the ciliary muscle ring diameter decreased (0.08 mm/D) and the muscle thinned posteriorly (0.008 mm/D), allowing the lens to shorten equatorially (0.07 mm/D) and thicken axially (0.06 mm/D) (all p < 0.03).

Conclusions: Refractive error is significantly correlated with not only the axial dimensions but also the anterior equatorial dimension of the adult eye. Further testing and development of accommodating intraocular lenses should account for differences in patients' preoperative refractive error.
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http://dx.doi.org/10.1097/OPX.0000000000000757DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4692191PMC
January 2016

Previous Driving Experience, but Not Vision, Is Associated With Motor Vehicle Collision Rate in Bioptic Drivers.

Invest Ophthalmol Vis Sci 2015 Oct;56(11):6326-32

The Ohio State University College of Optometry Columbus, Ohio, United States.

Purpose: Bioptic telescopic spectacles (BTS) consist of a small telescope (or telescopes) mounted high in a pair of spectacle lenses. More than 40 states allow for some form of bioptic driving licensure for people with decreased central vision. The purpose of this study was to determine significant associations among previous driving experience, vision, and motor vehicle collisions (MVCs) for bioptic drivers in Ohio.

Methods: We conducted a retrospective study of patients who received a vision examination and subsequently obtained bioptic licensure. We obtained driving records from the Ohio Bureau of Motor Vehicles in order to determine MVC involvement. Relationships among vision measures, age, sex, previous experience, and MVCs were investigated using time-to-event analysis and the Cox proportional hazards regression model.

Results: We identified 237 bioptic drivers (65% male). Age at initial exam ranged from 16 to 81 years, and mean visual acuity was approximately 20/120. The number of MVCs per driver ranged from 0 to 11, with 124 (52%) drivers having had at least one MVC. Visual acuity and contrast sensitivity were not significant predictors of MVC. Drivers without previous driving experience were significantly more likely to have been involved in an MVC (P < 0.001), and this association remained significant after adjusting for age and sex (P = 0.01). The rate of MVC per year decreased steadily over a 10-year period for drivers without previous experience.

Conclusions: Previous nonbioptic driving experience, but not visual acuity or contrast sensitivity, was associated with yearly MVC rate in bioptic drivers.
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http://dx.doi.org/10.1167/iovs.15-16882DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4594499PMC
October 2015

Correction of low levels of astigmatism.

J Cataract Refract Surg 2015 Aug;41(8):1641-9

From the College of Optometry (Bullimore), University of Houston, Houston, Texas, Gain Consulting Services (Spooner), San Francisco, California, and the Dishler Laser Institute (Dishler), Greenwood Village, Colorado, USA; Carl Zeiss Meditec AG (Sluyterman), Jena, Germany.

Purpose: To reevaluate the analysis of the correction of astigmatism.

Setting: Academia, industry, and private practice.

Design: Evaluation of diagnostic test or technology.

Methods: Astigmatic refractive surgery outcomes are based on vector methods, including the correction index (also known as the correction ratio), which is the ratio of the surgically induced astigmatism to the target induced astigmatism (TIA). Mean correction indices substantially greater than 1 have been reported for astigmatic corrections less than 1.00 diopter (D) and as representing systematic overcorrection. We hypothesize that this reflects a limitation of the correction index rather than systematic flaws in treatments. The theoretical mathematic behavior of the correction index was analyzed, accounting for variability in astigmatism measurement. Then, the impact of cylinder measurement variability on the mean correction index was modeled. A Monte Carlo simulation was performed and calculated 10 000 values of correction index for various values of TIA. Finally, correction indices from published and unpublished studies of refractive lasers were compared with the simulations.

Results: The mean correction index is always greater than 1 for the case of a perfect refractive correction; however, for astigmatic corrections less than 1.00 D, the mean correction index increases sharply because the measurement variability is similar in magnitude to TIA. Almost all previous studies show the predicted increase in the correction index for low astigmatic corrections.

Conclusion: The correction index is a useful vector-based metric for the evaluation of refractive procedures, but mean values greater than 1 should be anticipated for lower astigmatic treatments and do not necessarily represent systematic overcorrection.

Financial Disclosure: Dr. Bullimore is a consultant to Alcon Surgical, Inc., Carl Zeiss Meditec AG, Digital Vision Systems, Essilor, Innovega, Inc., and Paragon Vision Sciences, Inc. Dr. Spooner is a consultant to Alcon Surgical, Inc., Carl Zeiss Meditec AG, Digital Vision Systems, Thru-Focus Optics LLC, and i2eyediagnostics, Ltd. Dr. Dishler is a consultant to Carl Zeiss Meditec AG and Revision Optics, Inc. Dr. Sluyterman is an employee of Carl Zeiss Meditec AG.
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http://dx.doi.org/10.1016/j.jcrs.2014.12.060DOI Listing
August 2015

Myopia: an epidemic of possibilities?

Authors:
Mark A Bullimore

Ophthalmic Physiol Opt 2015 Jul;35(4):349-51

University of Houston College of Optometry, Houston, TX, USA.

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http://dx.doi.org/10.1111/opo.12222DOI Listing
July 2015

Vision, training hours, and road testing results in bioptic drivers.

Optom Vis Sci 2015 Apr;92(4):395-403

*OD, PhD, FAAO †OD, FAAO ‡MCOptom, PhD, FAAO The Ohio State University College of Optometry, Columbus, Ohio (BED, REF, TWR); and University of Houston College of Optometry, Houston, Texas (MAB).

Purpose: Bioptic telescopic spectacles can be used by people with central visual acuity that does not meet the state standards to obtain an unrestricted driver's license. The purpose of this study was to examine the relationships among visual and demographic factors, training hours, and the results of road testing for bioptic drivers.

Methods: A retrospective study of patients who received an initial daylight bioptic examination at the Ohio State University and subsequently received a bioptic license was conducted. Data were collected on vision including visual acuity, contrast sensitivity, and visual field. Hours of driver training and results of Highway Patrol road testing were extracted from records. Relationships among vision, training hours, and road testing were analyzed.

Results: Ninety-seven patients who completed a vision examination between 2004 and 2008 and received daylight licensure with bioptic telescopic spectacles were included. Results of the first Highway Patrol road test were available for 74 patients. The median (interquartile range) hours of training before road testing was 21 (17) hours (range, 9 to 75 hours). Candidates without previous licensure were younger (p < 0.001) and had more documented training (p < 0.001). Lack of previous licensure and more training were significantly associated with having failed a portion of the Highway Patrol test and points deducted on the road test.

Conclusions: New bioptic drivers without previous nonbioptic driving experience required more training and performed more poorly on road testing for licensure than those who had previous nonbioptic licensure. No visual factor was predictive of road testing results after adjustment for previous experience. The hours of training received remained predictive of road testing outcome even with adjustment for previous experience. These results suggest that previous experience and trainer assessments should be investigated as potential predictors of road safety in bioptic drivers in future studies.
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http://dx.doi.org/10.1097/OPX.0000000000000547DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4423412PMC
April 2015

Myopia control: the time is now.

Authors:
Mark A Bullimore

Ophthalmic Physiol Opt 2014 May 27;34(3):263-6. Epub 2014 Mar 27.

College of Optometry, University of Houston, Houston, TX, USA.

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http://dx.doi.org/10.1111/opo.12130DOI Listing
May 2014

Validation of an iPad test of letter contrast sensitivity.

Optom Vis Sci 2014 Mar;91(3):291-6

*OD, PhD, FAAO †OD, MS, FAAO ‡OD, FAAO §MCOptom, PhD, FAAO School of Optometry (PSK, MEJ, EJK), Indiana University, Bloomington, Indiana; and College of Optometry (MAB), University of Houston, Houston, Texas.

Purpose: An iPad-based letter contrast sensitivity test was developed (ridgevue.com) consisting of two letters on each page of an iBook. The contrast decreases from 80% (logCS = 0.1) to 0.5% (logCS = 2.3) by 0.1 log units per page. The test was compared to the Pelli-Robson Test and the Freiburg Acuity and Contrast Test.

Methods: Twenty normally sighted subjects and 20 low-vision subjects were tested monocularly at 1 m using each test wearing their habitual correction. After a 5-minute break, subjects were retested with each test in reverse order. Two different letter charts were used for both the Pelli-Robson and iPad tests, and the order of testing was varied systematically. For the Freiburg test, the target was a variable contrast Landolt C presented at eight possible orientations and used a 30-trial Best PEST procedure. Repeatability and agreement were assessed by determining the 95% limits of agreement (LoA) ± 1.96 SD of the differences between administrations or tests.

Results: All three tests showed good repeatability in terms of the 95% LoA: iPad = ± 0.19, Pelli-Robson = ± 0.19, and Freiburg = ± 0.15. The iPad test showed good agreement with the Freiburg test with similar mean (± SD) logCS (iPad = 1.98 ± 0.11, Freiburg = 1.96 ± 0.06) and with narrow 95% LoA (± 0.24), but the Pelli-Robson test gave significantly lower values (1.65 ± 0.04). Low-vision subjects had slightly poorer repeatability (iPad = ± 0.24, Pelli-Robson = ± 0.23, Freiburg = ± 0.21). Agreement between the iPad and Freiburg tests was good (iPad = 1.45 ± 0.40, Freiburg = 1.54 ± 0.37), but the Pelli-Robson test gave significantly lower values (1.30 ± 0.30).

Conclusions: The iPad test showed similar repeatability and may be a rapid and convenient alternative to some existing measures. The Pelli-Robson test gave lower values than the other tests.
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http://dx.doi.org/10.1097/OPX.0000000000000158DOI Listing
March 2014

The risk of microbial keratitis with overnight corneal reshaping lenses.

Optom Vis Sci 2013 Sep;90(9):937-44

College of Optometry, The University of Houston, Houston, TX, USA.

Purpose: To estimate the incidence of microbial keratitis (MK) associated with overnight corneal reshaping contact lenses and to compare rates in children and adults.

Methods: A retrospective study of randomly selected practitioners, stratified by order volume and lens company, was conducted. Practitioners were invited to participate and those agreeing were asked to provide deidentified patient information for up to 50 lens orders and to complete a comprehensive event form for any of these patients who have attended an unscheduled visit for a painful red eye. Duration of contact lens wear was calculated from the original fitting date or January 2005 (whichever was later) to when the patient was last seen by the practitioner wearing the lenses on a regular basis. Cases of MK were classified by majority decision of a 5-member expert panel.

Results: For the 191 practitioners who could be contacted, 119 (62%) agreed to participate. Subsequently, 11 withdrew, 22 did not respond, and 86 (43%) returned completed forms corresponding to 2202 lens orders and 1494 patients. Limiting the sample to those patients with at least 3 months of documented contact lens wear since 2005 resulted in a sample of 1317 patients; 640 adults (49%) and 677 children (51%) representing 2599 patient-years of wear (adults = 1164; children = 1435). Eight events of corneal infiltrates associated with a painful red eye were reported (six in children and two in adults). Two were classified as MK. Both occurred in children but neither resulted in a loss of visual acuity. The overall estimated incidence of MK is 7.7 per 10,000 years of wear (95% confidence interval [CI] = 0.9 to 27.8). For children, the estimated incidence of MK is 13.9 per 10,000 patient-years (95% CI = 1.7 to 50.4). For adults, the estimated incidence of MK is 0 per 10,000 patient-years (95% CI = 0 to 31.7).

Conclusions: The risk of MK with overnight corneal reshaping contact lenses is similar to that with other overnight modalities. The fact that the CIs for the rates estimated overlap should not be interpreted as evidence of no difference. True differences fewer than 50 cases per 10,000 patient-years were beyond the study's power of detection.
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http://dx.doi.org/10.1097/OPX.0b013e31829cac92DOI Listing
September 2013

Agreement between a partial coherence interferometer and 2 manual keratometers.

J Cataract Refract Surg 2013 Oct 19;39(10):1550-60. Epub 2013 Jul 19.

From the University of Houston (Bullimore), College of Optometry, Houston, Texas, USA, and Carl Zeiss Meditec AG (Buehren, Bissmann), Jena, Germany. Electronic address:

Purpose: To establish repeatability and validity of a partial coherence interferometry (PCI) device in patients with astigmatism.

Setting: Industry and university.

Design: Observational studies.

Methods: A prospective study determined the agreement between the IOLMaster 500 PCI device and the Marco 1-position manual keratometer for measurement of mean corneal power, astigmatic power, and axis. Interinstrument and interoperator reproducibility was also assessed. A retrospective study determined the agreement between the PCI device and the Javal 2-position manual keratometer. Repeatability was also assessed. The 95% limits of agreement (LoA) were determined for all comparisons.

Results: Comparing the PCI device and the 1-position manual keratometer, the axis was within 5 degrees in 72.1% of eyes; the cylinder power differed by 0.18 diopter (D) (95% LoA, ±0.45 D) and the mean power by 0.33 D (95% LoA, ±0.25 D). Comparing the PCI device and the 2-position manual keratometer, the axis was within 5 degrees in 77.1% of eyes. The mean difference in cylinder power between the 2 instruments was close to zero (95% LoA, ±0.37 D); however, the mean power differed by 0.34 D (95% LoA, ±0.25 D). The repeatability of the PCI device was better than that of both manual keratometers.

Conclusions: Agreement between the PCI device and the 2-position manual keratometer for measures of corneal astigmatism and axis was excellent. The 1-position manual keratometer gave slightly lower estimates of corneal astigmatism, although the agreement for axis was excellent. Thus, the PCI device is an appropriate choice for the calculation of toric intraocular lenses.

Financial Disclosure: Dr. Bullimore is a consultant to Carl Zeiss Meditec AG and Alcon Surgical, Inc. Drs. Buehren and Bissmann are employees of Carl Zeiss Meditec AG.
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http://dx.doi.org/10.1016/j.jcrs.2013.03.034DOI Listing
October 2013

Comparison of progressive addition lenses by direct measurement of surface shape.

Optom Vis Sci 2013 Jun;90(6):565-75

Department of Optometry, Shu Zen Junior College of Medicine and Management, Kaohsiung, Taiwan.

Purpose: To compare the optical properties of five state-of-the-art progressive addition lenses (PALs) by direct physical measurement of surface shape.

Methods: Five contemporary freeform PALs (Varilux Comfort Enhanced, Varilux Physio Enhanced, Hoya Lifestyle, Shamir Autograph, and Zeiss Individual) with plano distance power and a +2.00-diopter add were measured with a coordinate measuring machine. The front and back surface heights were physically measured, and the optical properties of each surface, and their combination, were calculated with custom MATLAB routines. Surface shape was described as the sum of Zernike polynomials. Progressive addition lenses were represented as contour plots of spherical equivalent power, cylindrical power, and higher order aberrations (HOAs). Maximum power rate, minimum 1.00-DC corridor width, percentage of lens area with less than 1.00 DC, and root mean square of HOAs were also compared.

Results: Comfort Enhanced and Physio Enhanced have freeform front surfaces, Shamir Autograph and Zeiss Individual have freeform back surfaces, and Hoya Lifestyle has freeform properties on both surfaces. However, the overall optical properties are similar, regardless of the lens design. The maximum power rate is between 0.08 and 0.12 diopters per millimeter and the minimum corridor width is between 8 and 11 mm. For a 40-mm lens diameter, the percentage of lens area with less than 1.00 DC is between 64 and 76%. The third-order Zernike terms are the dominant high-order terms in HOAs (78 to 93% of overall shape variance). Higher order aberrations are higher along the corridor area and around the near zone. The maximum root mean square of HOAs based on a 4.5-mm pupil size around the corridor area is between 0.05 and 0.06 µm.

Conclusions: This nonoptical method using a coordinate measuring machine can be used to evaluate a PAL by surface height measurements, with the optical properties directly related to its front and back surface designs.
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http://dx.doi.org/10.1097/OPX.0b013e3182923ff6DOI Listing
June 2013

Quantification of age-related and per diopter accommodative changes of the lens and ciliary muscle in the emmetropic human eye.

Invest Ophthalmol Vis Sci 2013 Feb 7;54(2):1095-105. Epub 2013 Feb 7.

College of Optometry, State University of New York, New York, NY, USA.

Purpose: To calculate age-related and per diopter (D) accommodative changes in crystalline lens and ciliary muscle dimensions in vivo in a single cohort of emmetropic human adults ages 30 to 50 years.

Methods: The right eyes of 26 emmetropic adults were examined using ultrasonography, phakometry, anterior segment optical coherence tomography, and high resolution magnetic resonance imaging. Accommodation was measured both subjectively and objectively.

Results: In agreement with previous research, older age was linearly correlated with a thicker lens, steeper anterior lens curvature, shallower anterior chamber, and lower lens equivalent refractive index (all P < 0.01). Age was not related to ciliary muscle ring diameter (CMRD) or lens equatorial diameter (LED). With accommodation, lens thickness increased (+0.064 mm/D, P < 0.001), LED decreased (-0.075 mm/D, P < 0.001), CMRD decreased (-0.105 mm/D, P < 0.001), and the ciliary muscle thickened anteriorly (+0.013 to +0.026 mm/D, P < 0.001) and thinned posteriorly (-0.011 to -0.015, P < 0.01). The changes per diopter of accommodation in LED, CMRD, and ciliary muscle thickness were not related to subject age.

Conclusions: The per diopter ciliary muscle contraction is age independent, even as total accommodative amplitude declines. Quantifying normal biometric dimensions of the accommodative structures and changes with age and accommodative effort will further the development of new IOLs designed to harness ciliary muscle forces.
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http://dx.doi.org/10.1167/iovs.12-10619DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3567753PMC
February 2013

Comparison of three techniques in measuring progressive addition lenses.

Optom Vis Sci 2012 Nov;89(11):1564-73

Shu Zen College of Medicine and Management, Department of Optometry, Taiwan.

Purpose: To measure progressive addition lenses (PALs) by three techniques and to compare the differences across techniques.

Methods: Five contemporary PALs (Varilux Comfort Enhanced, Varilux Physio Enhanced, Hoya Lifestyle, Shamir Autograph, and Zeiss individual) with plano distance power and a +2.00 diopters (D) add were evaluated under the condition of lateral displacement of the lens (no rotation and no tilt) using three methods. A Hartmann-Shack wavefront sensor (HSWFS) on a custom-built optical bench was used to capture and measure wavefront aberrations. A Rotlex Class Plus lens analyzer operating as a moiré interferometer was used to measure spherical and cylindrical powers. A coordinate measuring machine (CMM) was used to measure front and back surfaces of PALs and converted to desired optical properties. The data were analyzed with MATLAB programs. Contour plots of spherical equivalent power, cylindrical power, and higher-order aberrations (HOAs) in all PALs were generated to compare their differences.

Results: The differences in spherical equivalent and cylinder at distance, near, and progressive corridor areas among the HSWFS, Rotlex, and CMM methods were close to zero in all five PALs. The maximum differences are approximately 0.50 D and located below the near power zone and the edge areas of the lens when comparing the HSWFS and CMM with the Rotlex. HOAs measured both by the HSWFS and CMM were highest in the corridor area and the area surrounding the near zone in all PALs. The HOAs measured by the CMM were lower than those from the HSWFS by 0.02 to 0.04 μm.

Conclusions: The three measurement methods are comparable for measuring spherical and cylindrical power across PALs. The non-optical method, CMM, can be used to evaluate the optical properties of a PAL by measuring front and back surface height measurements, although its estimates of HOAs are lower than those from the HSWFS.
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http://dx.doi.org/10.1097/OPX.0b013e31826ca26bDOI Listing
November 2012

The effect of phenylephrine on the ciliary muscle and accommodation.

Optom Vis Sci 2012 Oct;89(10):1507-11

College of Optometry, The State University of New York, New York, New York 10036, USA.

Purpose: To objectively measure changes in the human ciliary muscle dimensions in vivo after instillation of topical phenylephrine, a mydriatic and vasodilating agent.

Methods: A cross-sectional study of 25 healthy young adults was conducted. Measurements of pupil size, accommodation, and ciliary muscle thickness were made both before and 30 min after instillation of 1% proparacaine and 2.5% phenylephrine. Accommodation was measured in three ways: subjectively using a push-up technique and Royal Air Force (RAF) rule, and objectively using both the Grand Seiko autorefractor and PowerRefractor. Images of the temporal ciliary muscle were acquired using the Visante Anterior Segment Optical Coherence Tomographer (OCT). Ciliary muscle images were objectively analyzed using a computer-based segmentation technique.

Results: Amplitude of accommodation using the push-up test was reduced by about 1 D with phenylephrine (p < 0.001). Phenylephrine did not change the accommodative response to a 4 D Badal target as measured by either autorefraction or photorefraction (p > 0.30). There was statistically significant thickening of the anterior region and thinning of the posterior region of the ciliary muscle with accommodation (p < 0.001, all locations). Phenylephrine did not affect either baseline ciliary muscle thickness or the accommodative contraction of the muscle (p > 0.09).

Conclusions: Low-dose phenylephrine does not affect ciliary muscle dimensions, ciliary muscle contractility, or accommodative response to a 4 D near target.
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http://dx.doi.org/10.1097/OPX.0b013e318269c8d0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3607430PMC
October 2012

Morphometric analysis and classification of glaucomatous optic neuropathy using radial polynomials.

J Glaucoma 2012 Jun-Jul;21(5):302-12

College of Optometry, University of Houston, Houston, TX 77204-2020, USA.

Purpose: To quantify the morphological features of the optic nerve head using radial polynomials, to use these morphometric models as the basis for classification of glaucomatous optic neuropathy via an automated decision tree induction algorithm, and to compare these classification results with established procedures.

Methods: A cohort of patients with high-risk ocular hypertension or early glaucoma (n=179) and a second cohort of normal subjects (n=96) were evaluated for glaucomatous optic neuropathy using stereographic disc photography and confocal scanning laser tomography. Morphological features of the optic nerve head region were modeled from the tomography data using pseudo-Zernike radial polynomials and features derived from these models were used as the basis for classification by a decision tree induction algorithm. Decision tree classification performance was compared with expert classification of stereographic disc photographs and analysis of neural retinal rim thickness by Moorfields Regression Analysis (MRA).

Results: Root mean squared error of the morphometric models decreased asymptotically with additional polynomial coefficients, from 62±0.5 (32 coefficients) to 32±5.7 μm (256 coefficients). Optimal morphometric classification was derived from a subset of 64 total features and had low sensitivity (69%), high specificity (88%), very good accuracy (80%), and area under the receiver operating characteristic curve (AUROC) was 88% (95% confidence interval, 78%-98%). In comparison, MRA classification of the same records had a comparatively poorer sensitivity (55%), but had higher specificity (95%), with similar overall accuracy (78%) and AUROC curve, 83% (95% CI, 70%-96%).

Conclusions: Pseudo-Zernike radial polynomials provide a mathematically compact and faithful morphological representation of the structural features of the optic nerve head. This morphometric method of glaucomatous optic neuropathy classification has greater sensitivity, and similar overall classification performance (AUROC) when compared with classification by neural retinal rim thickness by MRA in patients with high-risk ocular hypertension and early glaucoma.
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http://dx.doi.org/10.1097/IJG.0b013e31820d7e6aDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3163012PMC
August 2012