Publications by authors named "Jod S Mehta"

11 Publications

  • Page 1 of 1

Interventions for the management of CMV-associated anterior segment inflammation.

Cochrane Database Syst Rev 2017 08 24;8:CD011908. Epub 2017 Aug 24.

Singapore National Eye Centre, 11 Third Hospital Avenue, Singapore, Singapore, 168751.

Background: Cytomegalovirus (CMV) is a virus that usually affects people with reduced immunity. In recent years, this virus has been thought to cause repeated inflammation in the eye, in otherwise healthy people. This form of inflammation can cause damage to the cornea (the outer layer of the eye) or to the optic nerve by causing secondary glaucoma, or to both, leading to visual loss.

Objectives: Our primary objective was to assess the effects of drug therapies for the treatment of CMV-associated anterior segment inflammation.Our secondary objective was to determine the optimal dose and duration of treatment with respect to recurrence and adverse effects.

Search Methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 2), MEDLINE Ovid (1946 to 21 March 2017), Embase Ovid (1947 to 21 March 2017), the ISRCTN registry (www.isrctn.com/editAdvancedSearch); searched 21 March 2017, ClinicalTrials.gov (www.clinicaltrials.gov); searched 21 March 2017, and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 21 March 2017. We did not use any date or language restrictions in the electronic searches for trials. Two review authors independently reviewed the titles and abstracts.

Selection Criteria: We searched for randomised controlled trials (RCTs) on the management of CMV-associated anterior segment inflammation.

Data Collection And Analysis: We planned to have two review authors independently extract data from reports of included studies and analyse data based on methods expected by Cochrane.

Main Results: We did not identify any RCTs that met our inclusion criteria.

Authors' Conclusions: There is currently no good-quality evidence on the management of CMV-associated anterior segment inflammation. Ideally, a well-designed RCT is needed to evaluate the effectiveness of different anti-CMV medications as well as the optimal dose and duration.
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http://dx.doi.org/10.1002/14651858.CD011908.pub2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6483705PMC
August 2017

The effects of a low-energy, high frequency liquid optic interface femtosecond laser system on lens capsulotomy.

Sci Rep 2016 Apr 19;6:24352. Epub 2016 Apr 19.

Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore, Singapore.

The introduction of femtosecond laser assisted cataract surgery (FLACS) is a paradigm changing approach in cataract surgery, the most commonly performed surgical procedure. FLACS has the potential to optimize the creation of an anterior lens capsulotomy, a critical step in accessing the cataractous lens. The merits of using a laser instead of a manual approach include a potentially more circular, consistent, and stronger aperture. In this study we demonstrated for the first time in both a porcine and human experimental setting that with a low energy, high repetition FLACS system, that a circular, smooth and strong capsulotomy was achievable. While there was no demonstrable difference in the resistance to rupture before or after the removal of the nucleus, larger capsulotomies had an increase in tensile strength. The LDV Z8 system appeared to create circular, rupture-resistant and smooth capsulotomies in both porcine and more importantly human globes.
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http://dx.doi.org/10.1038/srep24352DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4835735PMC
April 2016

Prophylactic Vancomycin Drops Reduce the Severity of Early Bacterial Keratitis in Keratoprosthesis.

PLoS One 2015 13;10(10):e0139653. Epub 2015 Oct 13.

Singapore Eye Research Institute, Singapore; Singapore National Eye Centre, Singapore; Department of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore; Nanyang Technological University, Singapore.

Background: Artificial cornea transplantation, keratoprosthesis, improves vision for patients at high risk of failure with human cadaveric cornea. However, post-operative infection can cause visual loss and implant extrusion in 3.2-17% of eyes. Long-term vancomycin drops are recommended following keratoprosthesis to prevent bacterial keratitis. Evidence, though, in support of this practice is poor. We investigated whether prophylactic vancomycin drops prevented bacterial keratitis in an animal keratoprosthesis model.

Methodology: Twenty-three rabbits were assigned either to a prophylactic group (n = 13) that received vancomycin 1.4% drops 5 times/day from keratoprosthesis implantation to sacrifice, or a non-prophylactic group (n = 10) that received no drops. All rabbits had Staphylococcus aureus inoculation into the cornea at 7-12 days post-implantation and were sacrificed at predetermined time-points. Prophylactic and non-prophylactic groups were compared with slit-lamp photography (SLP), anterior segment optical coherence tomography (AS-OCT), and histology, immunohistochemistry and bacterial quantification of excised corneas. Corneal vancomycin pharmacokinetics were studied in 8 additional rabbits.

Results: On day 1 post-inoculation, the median SLP score and mean±SEM AS-OCT corneal thickness (CT) were greater in the non-prophylactic than the prophylactic group (11 vs. 1, p = 0.049 and 486.9±61.2 vs. 327.4±37.1 μm, p = 0.029 respectively). On days 2 and 4, SLP scores and CT were not significantly different. Immunohistochemistry showed a greater CD11b+ve/non-CD11b+ve cell ratio in the non-prophylactic group (1.45 vs. 0.71) on day 2. Bacterial counts were not significantly different between the two groups. Corneal vancomycin concentration (2.835±0.383 μg/ml) exceeded minimum inhibitory concentration (MIC) for Staphylococcus aureus only after 16 days of vancomycin drops. Two of 3 rabbits still developed infection despite bacterial inoculation after 16 days of prophylactic drops.

Conclusions: Prophylactic vancomycin drops provided short-term benefit, but did not prevent infection. Achieving MIC in the cornea was not sufficient to prevent Staphylococcus aureus keratitis. Patients should continue to be counselled regarding the risk of infection following keratoprosthesis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0139653PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4604170PMC
June 2016

Enhancement of Corneal Visibility in Optical Coherence Tomography Images Using Corneal Adaptive Compensation.

Transl Vis Sci Technol 2015 May 15;4(3). Epub 2015 May 15.

Université de la Polynésie française, Tahiti, French Polynesia.

Purpose: To improve the contrast of optical coherence tomography (OCT) images of the cornea (post processing).

Methods: We have recently developed standard compensation (SC) algorithms to remove light attenuation artifacts. A more recent approach, namely adaptive compensation (AC), further limited noise overamplification within deep tissue regions. AC was shown to work efficiently when all A-scan signals were fully attenuated at high depth. But in many imaging applications (e.g., OCT imaging of the cornea), such an assumption is not satisfied, which can result in strong noise overamplification. A corneal adaptive compensation (CAC) algorithm was therefore developed to overcome such limitation. CAC benefited from local A-scan processing (rather than global as in AC) and its performance was compared with that of SC and AC using Fourier-domain OCT images of four human corneas.

Results: CAC provided considerably superior image contrast improvement than SC or AC did, with excellent visibility of the corneal stroma, low noise overamplification, homogeneous signal amplification, and high contrast. Specifically, CAC provided mean interlayer contrasts (a measure of high stromal visibility and low noise) greater than 0.97, while SC and AC provided lower values ranging from 0.38 to 1.00.

Conclusion: CAC provided considerable improvement compared with SC and AC by eliminating noise overamplification, while maintaining all benefits of compensation, thus making the corneal endothelium and corneal thickness easily identifiable.

Translational Relevance: CAC may find wide applicability in clinical practice and could contribute to improved morphometric and biomechanical understanding of the cornea.
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http://dx.doi.org/10.1167/tvst.4.3.3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4451879PMC
May 2015

Manual small incision cataract surgery (MSICS) with posterior chamber intraocular lens versus extracapsular cataract extraction (ECCE) with posterior chamber intraocular lens for age-related cataract.

Cochrane Database Syst Rev 2014 Nov 18(11):CD008811. Epub 2014 Nov 18.

Singapore National Eye Centre, 11 Third Hospital Avenue, Singapore, Singapore, 168751.

Background: Age-related cataract is the opacification of the lens, which occurs as a result of denaturation of lens proteins. Age-related cataract remains the leading cause of blindness globally, except in the most developed countries. A key question is what is the best way of removing the lens, especially in lower income settings.

Objectives: To compare two different techniques of lens removal in cataract surgery: manual small incision surgery (MSICS) and extracapsular cataract extraction (ECCE).

Search Methods: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 8), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to September 2014), EMBASE (January 1980 to September 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to September 2014), Web of Science Conference Proceedings Citation Index- Science (CPCI-S), (January 1990 to September 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 23 September 2014.

Selection Criteria: We included randomised controlled trials (RCTs) only. Participants in the trials were people with age-related cataract. We included trials where MSICS with a posterior chamber intraocular lens (IOL) implant was compared to ECCE with a posterior chamber IOL implant.

Data Collection And Analysis: Data were collected independently by two authors. We aimed to collect data on presenting visual acuity 6/12 or better and best-corrected visual acuity of less than 6/60 at three months and one year after surgery. Other outcomes included intraoperative complications, long-term complications (one year or more after surgery), quality of life, and cost-effectiveness. There were not enough data available from the included trials to perform a meta-analysis.

Main Results: Three trials randomly allocating people with age-related cataract to MSICS or ECCE were included in this review (n = 953 participants). Two trials were conducted in India and one in Nepal. Trial methods, such as random allocation and allocation concealment, were not clearly described; in only one trial was an effort made to mask outcome assessors. The three studies reported follow-up six to eight weeks after surgery. In two studies, more participants in the MSICS groups achieved unaided visual acuity of 6/12 or 6/18 or better compared to the ECCE group, but overall not more than 50% of people achieved good functional vision in the two studies. 10/806 (1.2%) of people enrolled in two trials had a poor outcome after surgery (best-corrected vision less than 6/60) with no evidence of difference in risk between the two techniques (risk ratio (RR) 1.58, 95% confidence interval (CI) 0.45 to 5.55). Surgically induced astigmatism was more common with the ECCE procedure than MSICS in the two trials that reported this outcome. In one study there were more intra- and postoperative complications in the MSICS group. One study reported that the costs of the two procedures were similar.

Authors' Conclusions: There are no other studies from other countries other than India and Nepal and there are insufficient data on cost-effectiveness of each procedure. Better evidence is needed before any change may be implemented. Future studies need to have longer-term follow-up and be conducted to minimize biases revealed in this review with a larger sample size to allow examination of adverse events.
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http://dx.doi.org/10.1002/14651858.CD008811.pub3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173714PMC
November 2014

Targeted corneal transplantation.

Curr Opin Ophthalmol 2012 Jul;23(4):324-9

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, 3/F Hong Kong Eye Hospital, 147K Argyle Street, Mongkok, Kowloon, Hong Kong.

Purpose Of Review: Corneal transplantation surgery has moved from an era of conventional penetrating keratoplasty to selective replacement of the diseased corneal layer with complementary healthy donor corneal tissue. Anterior lamellar transplantation surgeries do not involve replacement of corneal endothelium, consequently eliminating the occurrence of endothelial rejection. Similarly, in diseases affecting the corneal endothelium, selective replacement with a lamellar lenticule bearing healthy endothelium provides better outcomes in terms of ocular surface, lesser astigmatism and quick visual recovery. In addition to the advantages of enhanced surgical outcomes, targeted corneal transplantation allows the use of one donor cornea for more than one recipient, thereby offering a viable solution to the problem of paucity of donor corneas.

Recent Findings: Evolving techniques of corneal transplantation have enabled better utilization of donor corneal tissue. Anterior lamellar as well as endothelial keratoplasty surgeries have become first-choice surgeries in appropriately selected cases. This review briefly discusses some of these novel surgical techniques.

Summary: A better understanding of targeted corneal transplantation would lead to adaptation of the concept of component corneal surgery. This would further enable the corneal surgeons to circumvent the problem of donor corneal shortage especially in the developing world.
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http://dx.doi.org/10.1097/ICU.0b013e32835484a1DOI Listing
July 2012

Manual small incision cataract surgery (MSICS) with posterior chamber intraocular lens versus extracapsular cataract extraction (ECCE) with posterior chamber intraocular lens for age-related cataract.

Cochrane Database Syst Rev 2012 Apr 18(4):CD008811. Epub 2012 Apr 18.

Singapore National Eye Centre, Singapore, Singapore.

Background: Age-related cataract is the opacification of the lens, which occurs as a result of denaturation of lens proteins. Age-related cataract remains the leading cause of blindness globally, except in the most developed countries. A key question is what is the best way of removing the lens, especially in lower income settings.

Objectives: To compare two different techniques of lens removal in cataract surgery: manual small incision surgery (MSICS) and extracapsular cataract extraction (ECCE).

Search Methods: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 1), MEDLINE (January 1950 to February 2012), EMBASE (January 1980 to February 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to February 2012), Web of Science Conference Proceedings Citation Index- Science (CPCI-S), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 14 February 2012.

Selection Criteria: We included randomised controlled trials (RCTs) only. Participants in the trials were people with age-related cataract. We included trials where MSICS with a posterior chamber intraocular lens (IOL) implant was compared to ECCE with a posterior chamber IOL implant.

Data Collection And Analysis: Data were collected independently by two authors. We aimed to collect data on presenting visual acuity 6/12 or better and best-corrected visual acuity of less than 6/60 at three months and one year after surgery. Other outcomes included intraoperative complications, long-term complications (one year or more after surgery), quality of life, and cost-effectiveness. There were not enough data available from the included trials to perform a meta-analysis.

Main Results: Three trials randomly allocating people with age-related cataract to MSICS or ECCE were included in this review (n = 953 participants). Two trials were conducted in India and one in Nepal. Trial methods, such as random allocation and allocation concealment, were not clearly described; in only one trial was an effort made to mask outcome assessors. The three studies reported follow-up six to eight weeks after surgery. In two studies, more participants in the MSICS groups achieved unaided visual acuity of 6/12 or 6/18 or better compared to the ECCE group, but overall not more than 50% of people achieved good functional vision in the two studies. 10/806 (1.2%) of people enrolled in two trials had a poor outcome after surgery (best-corrected vision less than 6/60) with no evidence of difference in risk between the two techniques (risk ratio (RR) 1.58, 95% confidence interval (CI) 0.45 to 5.55). Surgically induced astigmatism was more common with the ECCE procedure than MSICS in the two trials that reported this outcome. In one study there were more intra- and postoperative complications in the MSICS group. One study reported that the costs of the two procedures were similar.

Authors' Conclusions: There are no other studies from other countries other than India and Nepal and there are insufficient data on cost-effectiveness of each procedure. Better evidence is needed before any change may be implemented. Future studies need to have longer-term follow-up and be conducted to minimize biases revealed in this review with a larger sample size to allow examination of adverse events.
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http://dx.doi.org/10.1002/14651858.CD008811.pub2DOI Listing
April 2012

Management of corneal perforation.

Surv Ophthalmol 2011 Nov-Dec;56(6):522-38

Centre for Eye Research Australia, University of Melbourne, Australia.

Corneal perforation may be associated with prolapse of ocular tissue and requires prompt diagnosis and treatment. Although infectious keratitis is an important cause, corneal xerosis and collagen vascular diseases should be considered in the differential diagnosis, especially in cases that do not respond to conventional medical therapy. Although medical therapy is a useful adjunct, a surgical approach is required for most corneal perforations. Depending on the size and location of the corneal perforation, treatment options include gluing, amniotic membrane transplantation, and corneal transplantation.
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http://dx.doi.org/10.1016/j.survophthal.2011.06.003DOI Listing
January 2012

Biological and ultrastructural properties of acelagraft, a freeze-dried γ-irradiated human amniotic membrane.

Arch Ophthalmol 2010 Oct;128(10):1303-10

Singapore National Eye Centre, Singapore 168751.

Objectives: To compare the biological and ultrastructural properties of a commercially available decellularized and dehydrated human amniotic membrane (DDHAM) product with cryopreserved human amniotic membrane (CHAM) and to demonstrate the feasibility of DDHAM transplant in a case of chronic ocular surface disease.

Methods: Histologic examination, immunohistochemical examination for extracellular matrix molecules and growth factors, transmission and scanning electron microscopy, and atomic force microscopy were performed on both DDHAM and CHAM specimens. A DDHAM transplant was performed in a patient with chronic bullous keratopathy and ocular surface instability.

Results: Histologic examination and transmission electron microscopy revealed the disruption of the trilaminar structure of the basement membrane compared with CHAM, and immunohistochemical examination confirmed the loss of collagen IV and VII, laminin, and fibronectin in DDHAM. Lower levels of several growth factors were also seen in DDHAM compared with CHAM. Clinical transplant of DDHAM was, however, successful, with rapid reepithelialization.

Conclusion: Significant differences in composition and ultrastructure exist between DDHAM and CHAM but do not appear to compromise cell survival in vivo.

Clinical Relevance: The ease of storage and handling of DDHAM make it potentially valuable in ocular surface surgery, but its biological properties have not been well characterized, and there are also few data on its clinical application.
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http://dx.doi.org/10.1001/archophthalmol.2010.222DOI Listing
October 2010

Standardized arcuate keratotomy for postkeratoplasty astigmatism.

J Cataract Refract Surg 2005 Feb;31(2):297-301

Cornea & External Diseases Service, Moorfields Eye Hospital, London, United Kingdom.

Purpose: To assess the effect of standardized, paired arcuate keratotomy (AK) on the change in astigmatism in postkeratoplasty eyes.

Setting: Moorfields Eye Hospital, London, United Kingdom.

Methods: A retrospective review was conducted of 20 eyes of 19 patients having the same AK procedure regardless of the magnitude of the preoperative astigmatism. Each eye had a pair of 60-degree arc length incisions placed in the corneal stroma. The incisions were 600 mum deep and 6.0 mm apart. The preoperative and postoperative refractions and complications were analyzed. Astigmatic change was analyzed without regard to axis, as surgically induced refractive change, and using a modified polar plot of change in astigmatism.

Results: The mean cylinder was reduced from -10.99 diopters (D) +/- 4.26 (SD) to -3.33 +/- 2.18 D. There was no significant change in the mean spherical equivalent. There was a strong correlation between the magnitude of the preoperative cylinder and the magnitude of the change in astigmatism (R2 = 0.76). In 3 eyes, the surgically induced axis of astigmatism was more than 15 degrees from that expected.

Conclusions: In postkeratoplasty eyes, the change in the magnitude of astigmatism induced by standardized AK was proportional to the preoperative magnitude of astigmatism. Arcuate nomograms for congenital astigmatism have no role in the management of astigmatism in postkeratoplasty eyes.
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http://dx.doi.org/10.1016/j.jcrs.2004.07.025DOI Listing
February 2005