Publications by authors named "Margaret Strampe"

10 Publications

  • Page 1 of 1

Inpatient Adherence to Topical Glaucoma Medications before and after an Educational Intervention.

Ophthalmol Glaucoma 2020 Sep - Oct;3(5):339-342. Epub 2020 Apr 23.

Department of Ophthalmology & Visual Neurosciences, University of Minnesota-Minneapolis, Minneapolis, Minnesota.

Purpose: To assess the inpatient adherence rate and factors associated with adherence to topical glaucoma medications (TGMs) at a single academic institution throughout hospitalization before and after an educational intervention.

Design: Nonrandomized, comparative, retrospective study.

Participants: Inpatients 18 years of age and older admitted to a single academic hospital from January 2014 through June 2019 with a diagnosis of glaucoma who also received TGMs.

Methods: The medication administration record during admission was examined closely to determine if the TGMs were reconciled and administered correctly before and after an educational intervention with inpatient providers. A simple intervention reached various health care providers through an educational e-mail, communication in a weekly newsletter, and a morning report presentation. Adherence was defined as administration of more than 75% of recommended doses during the inpatient stay. Other collected variables included length of stay and primary diagnosis on admission.

Main Outcome Measures: Adherence rate to inpatient administration of TGMs.

Results: One hundred eighty-four patients (n = 142 before intervention; n = 42 after intervention) were included. The preintervention group had a total of 275 TGMs, of which 207 (75.3%) were administered in accordance with the adherence definition of this study. After the intervention phase, 49 of 56 (87.5%) TGMs were administered with appropriate adherence (P = 0.047). Adherence was associated significantly with a known outpatient medication regimen (P = 0.006) and correct admission reconciliation (P < 0.001).

Conclusions: When glaucoma patients requiring topical treatment are admitted, approximately one quarter of patients seem to not receive their medications appropriately. In this study, a simple educational intervention was able to improve adherence. To prevent daily fluctuations in intraocular pressure for vulnerable glaucoma patients, inpatient adherence to appropriate medication administration should be stressed continuously. While in the care of health care providers, inpatients should be afforded at least the opportunity to maintain adequate adherence, just as is carried out for other medications related to other chronic medical conditions.
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http://dx.doi.org/10.1016/j.ogla.2020.04.007DOI Listing
April 2020

Retinal Nerve Fibre Layer Thickness Increases with Decreasing Spectralis OCT Signal Strength in Normal Eyes.

Neuroophthalmology 2020 Apr 29;44(2):100-103. Epub 2019 Oct 29.

Department of Ophthalmology & Visual Neurosciences, University of Minnesota Medical School, Minneapolis, Minnesota, USA.

We sought to determine effect of signal strength on mean retinal nerve fibre layer (RNFL) using Spectralis optical coherence tomography (S-OCT). Thirty normal subjects (18 female, mean 37.9 years, range 24-61) were imaged with S-OCT using variably dense Bangerter foils to alter Q value (1 unit signal strength = 4 units Q). We found a statistically significant (p < 0.01) linear relationship (R = 0.8643) between Q and RNFL (1 unit decrease Q = 0.181 um mean RNFL increase). Unlike previous observations of Cirrus and Stratus OCT, we found RNFL thickness does not decrease with decreasing signal strength in S-OCT.
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http://dx.doi.org/10.1080/01658107.2019.1653934DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7202426PMC
April 2020

Assessing the Interocular Symmetry of Foveal Outer Nuclear Layer Thickness in Achromatopsia.

Transl Vis Sci Technol 2019 Sep 2;8(5):21. Epub 2019 Oct 2.

Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA.

Purpose: We examine the interocular symmetry of foveal outer nuclear layer (ONL) thickness measurements in subjects with achromatopsia (ACHM).

Methods: Images from 76 subjects with - or -associated ACHM and 42 control subjects were included in the study. Line or volume scans through the fovea of each eye were acquired using optical coherence tomography (OCT). Image quality was assessed for each image included in the analysis using a previously-described maximum tissue contrast index (mTCI) metric. Three foveal ONL thickness measurements were made by a single observer and interocular symmetry was assessed using the average of the three measurements for each eye.

Results: Mean (± standard deviation) foveal ONL thickness for subjects with ACHM was 79.7 ± 18.3 μm (right eye) and 79.2 ± 18.7 μm (left eye) compared to 112.9 ± 15.2 (right eye) and 112.1 ± 13.9 μm (left eye) for controls. Foveal ONL thickness did not differ between eyes for ACHM ( = 0.636) or control subjects ( = 0.434). No significant relationship between mTCI and observer repeatability was observed for either control ( = 0.140) or ACHM ( = 0.351) images.

Conclusions: While foveal ONL thickness is reduced in ACHM compared to controls, the high interocular symmetry indicates that contralateral ONL measurements could be used as a negative control in early-phase monocular treatment trials.

Translational Relevance: Foveal ONL thickness can be measured using OCT images over a wide range of image quality. The interocular symmetry of foveal ONL thickness in ACHM and control populations supports the use of the non-study eye as a control for clinical trial purposes.
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http://dx.doi.org/10.1167/tvst.8.5.21DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6779097PMC
September 2019

The Utility of Frame Averaging for Automated Algorithms in Analyzing Retinal Vascular Biomarkers in AngioVue OCTA.

Transl Vis Sci Technol 2019 Jan 18;8(1):10. Epub 2019 Jan 18.

Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA.

Purpose: This study proposes an optical coherence tomography angiography (OCTA) frame-averaging method and investigates the effects of the number of frames acquired and averaged on metrics quantifying the foveal avascular zone (FAZ), vessel morphology, and parafoveal intercapillary area (PICA).

Methods: Ten OCTA frames were acquired for each of the 19 subjects without known retinal disease using the AngioVue OCTA system. For each subject, acquired frames were ranked by an image quality metric. A subset of frames was then registered and averaged. The effects of the number of frames acquired and averaged on FAZ segmentation and metrics of FAZ geometry, vessel morphology, and PICA were analyzed.

Results: Frame averaging increased the accuracy of the automatically segmented FAZ region; for example, the absolute error in FAZ area decreased from 0.026 mm (1 frame) to 0.005 mm (5 frames). Averaging multiple frames exponentially decreased the estimated number of vessel endpoints and increased the average vessel length with a 32% decrease in number of endpoints and 14% increase in average vessel length when averaging five frames compared with one. Frame averaging also improved the precision of PICA estimates.

Conclusions: Averaging multiple OCTA frames using the Optovue AngioVue system reduced error in FAZ segmentation and improved the robustness of OCTA vessel morphology and perfusion metrics. The study demonstrated limited benefit in acquiring and averaging more than five frames.

Translational Relevance: Averaging multiple OCTA frames improved the robustness of OCTA foveal biomarkers with limited benefit when averaging more than five frames.
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http://dx.doi.org/10.1167/tvst.8.1.10DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6340247PMC
January 2019

Intraobserver Repeatability and Interobserver Reproducibility of Ellipsoid Zone Measurements in Retinitis Pigmentosa.

Transl Vis Sci Technol 2018 May 4;7(3):13. Epub 2018 Jun 4.

Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA.

Purpose: To examine repeatability and reproducibility of ellipsoid zone (EZ) width measurements in patients with retinitis pigmentosa (RP) using a longitudinal reflectivity profile (LRP) analysis.

Methods: We examined Bioptigen optical coherence tomography (OCT) scans from 48 subjects with RP or Usher syndrome. Nominal scan lengths were 6, 7, or 10 mm, and the lateral scale of each scan was calculated using axial length measurements. LRPs were generated from OCT line scans, and the peak corresponding to EZ was manually identified using ImageJ. The locations at which the EZ peak disappeared were used to calculate EZ width. Each scan was analyzed twice by each of two observers, who were masked to their previous measurements and those of the other observer.

Results: On average, horizontal width (HW) was significantly greater than vertical width (VW), and there was high interocular symmetry for both HW and VW. We observed excellent intraobserver repeatability with intraclass correlation coefficients (ICCs) ranging from 0.996 to 0.998 for HW and VW measurements. Interobserver reproducibility was also excellent for both HW (ICC = 0.989; 95% confidence interval [CI] = 0.983-0.995) and VW (ICC = 0.991; 95% CI = 0.985-0.996), with no significant bias observed between observers.

Conclusions: EZ width can be measured using LRPs with excellent repeatability and reproducibility. Our observation of greater HW than VW is consistent with previous observations in RP, though the reason for this anisotropy remains unclear.

Translational Relevance: We describe repeatability and reproducibility of a method for measuring EZ width in patients with RP or Usher syndrome. This approach could facilitate measurement of retinal band thickness and/or intensity.
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http://dx.doi.org/10.1167/tvst.7.3.13DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5989764PMC
May 2018

A case of congenital retinal macrovessel in an otherwise normal eye.

Am J Ophthalmol Case Rep 2017 Dec 9;8:18-21. Epub 2017 Sep 9.

Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, United States.

Purpose: To present the case of a 37-year-old female with a foveal macrovessel.

Observations: The patient had an incidental finding of congenital retinal macrovessel (CRM) in the left eye on optical coherence tomography (OCT). Visual acuity was normal, and slit lamp and dilated fundus examinations were otherwise unremarkable. OCT angiography (OCTA) imaging allowed for visualization of the depth profile of the vessel as well as the foveal avascular zone (FAZ). The FAZ and foveal pit were both smaller in the affected eye compared to the fellow eye.

Conclusions And Importance: We describe findings of OCTA imaging in a patient with CRM. Previous reports have relied on examination using fluorescein angiography, which does not provide sufficient axial resolution to discern the different vascular plexuses. This report further characterizes how this rare condition can affect foveal morphology and retinal vasculature.
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http://dx.doi.org/10.1016/j.ajoc.2017.09.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5731666PMC
December 2017

CELLULAR IMAGING OF THE TAPETAL-LIKE REFLEX IN CARRIERS OF RPGR-ASSOCIATED RETINOPATHY.

Retina 2019 Mar;39(3):570-580

Moorfields Eye Hospital, London, United Kingdom.

Purpose: To examine the features of the tapetal-like reflex (TLR) in female carriers of RPGR-associated retinopathy by means of adaptive optics scanning light ophthalmoscopy (AOSLO) and spectral domain optical coherence tomography.

Methods: Nine molecularly confirmed RPGR carriers and three healthy controls underwent ocular examination and the following retinal imaging modalities: color photography, near-infrared reflectance, fundus autofluorescence, spectral domain optical coherence tomography, and AOSLO. After identifying TLR areas across all imaging modalities, normalized local contrast of outer retinal bands on spectral domain optical coherence tomography was calculated and AOSLO-acquired photoreceptor mosaic analysis was performed.

Results: Seven carriers had TLR areas, which colocalized with increased rod photoreceptor reflectivity on confocal AOSLO and reduced cone photoreceptor densities. Parafoveal TLR areas also exhibited reduced local contrast (i.e., increased reflectivity) of the outer retinal bands on spectral domain optical coherence tomography (inner segment ellipsoid zone and outer segment interdigitation zone). Healthy controls did not show TLR.

Conclusion: The cellular resolution provided by AOSLO affords the characterization of the photoreceptor mosaic in RPGR carriers with a TLR. Features revealed include reduced cone density, increased cone inner segment diameter, and increased rod outer segment reflectivity.
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http://dx.doi.org/10.1097/IAE.0000000000001965DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5963958PMC
March 2019

Foveal Development in Infants Treated with Bevacizumab or Laser Photocoagulation for Retinopathy of Prematurity.

Ophthalmology 2018 03 2;125(3):444-452. Epub 2017 Nov 2.

Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin. Electronic address:

Purpose: To characterize and quantify early foveal development in preterm infants and to compare this development between eyes treated with intravitreal bevacizumab or laser photocoagulation (LPC) and untreated eyes.

Design: Observational case series.

Participants: One hundred thirty-one preterm infants undergoing retinopathy of prematurity (ROP) screenings.

Methods: Handheld OCT imaging was performed longitudinally on all patients. Thickness measurements of the inner and outer retinal layers were obtained at the foveal center and the nasal and temporal foveal rims. Comparisons between treated and untreated eyes were adjusted for age and other confounding variables.

Main Outcome Measures: Weekly change in inner and outer retinal thickness and presence of inner retinal layers, ellipsoid zone (EZ), and cystoid macular changes (CMCs).

Results: Outer retinal thickness at the foveal center increased by 3.1 μm/week in untreated eyes and 7.2 μm/week in bevacizumab-treated eyes (P = 0.038). Eyes treated with LPC had a lower probability of having all inner retinal layers present at the foveal center (odds ratio, 0.04; P = 0.001) and a lower probability of having the EZ present at the foveal center (odds ratio, 0.07; P = 0.024) compared with untreated eyes. Cystoid macular changes were found in 53% of patients and 22% of imaging sessions. The age-adjusted incidence of CMCs was not correlated with bevacizumab or LPC treatment.

Conclusions: Intravitreal bevacizumab therapy for ROP is associated with more rapid outer retinal thickening at the foveal center, whereas LPC is associated with earlier extrusion of the inner retinal layers and delayed development of the EZ at the foveal center. Long-term follow-up is needed to determine the visual significance of these findings.
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http://dx.doi.org/10.1016/j.ophtha.2017.09.020DOI Listing
March 2018

INTRAOPERATIVE IMAGING OF RETAINED PERFLUOROCARBON LIQUID USING SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY.

Retin Cases Brief Rep 2019 ;13(4):381-384

Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin.

Purpose: To report images of retained perfluorocarbon liquid (PFCL) on the surface of the retina obtained during an intraoperative use of hand-held spectral domain optical coherence tomography.

Methods: A 54-year-old man underwent pars plana vitrectomy with injection of PFCL to repair retinal detachment. Postoperatively, visually significant PFCL droplets were found to be retained in the eye. During the surgical removal of PFCL, a hand-held spectral domain optical coherence tomography was used to image the retina with the patient supine.

Results: Spectral domain optical coherence tomography images of the retained PFCL illustrated magnification of the areas of the outer retina underlying PFCL bubbles. The images obtained had some similarities to the patient's own observation of "floaters."

Conclusion: Droplets of PFCL over the retina result in imaging artifact, most likely due to a lensing effect caused by differences in refractive index between the PFCL and vitreous humor. Although the utility of hand-held spectral domain optical coherence tomography for infants has previously been established, this case presents further application of spectral domain optical coherence tomography in adults when imaging in the supine position is required.
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http://dx.doi.org/10.1097/ICB.0000000000000607DOI Listing
March 2020

Assessing the Accuracy of Foveal Avascular Zone Measurements Using Optical Coherence Tomography Angiography: Segmentation and Scaling.

Transl Vis Sci Technol 2017 Jun 9;6(3):16. Epub 2017 Jun 9.

Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA.

Purpose: The foveal avascular zone (FAZ) is altered in numerous diseases. We assessed factors (axial length, segmentation method, age, sex) impacting FAZ measurements from optical coherence tomography (OCT) angiography images.

Methods: We recruited 116 Caucasian subjects without ocular disease, and acquired two 3 × 3 mm AngioVue scans per each right eye (232 total scans). In images of the superficial plexus, the FAZ was segmented using the AngioVue semiautomatic nonflow measurement tool and ImageJ manual segmentation. In images from the full retinal thickness, the FAZ was segmented using the AngioAnalytics automatic FAZ tool. Repeatability, reliability, and reproducibility were calculated for FAZ measurements (acircularity, area).

Results: FAZ area (mean ± SD) for manual segmentation was 0.240 ± 0.0965 mm, greater than both semiautomatic (0.216 ± 0.0873 mm) and automatic (0.218 ± 0.0869 mm) segmentation ( < 0.05). Not correcting for axial length introduced errors up to 25% in FAZ area. Manual area segmentation had better repeatability (0.020 mm) than semiautomatic (0.043 mm) or automatic (0.056 mm). FAZ acircularity had better repeatability with automatic than manual segmentation (0.086 vs. 0.114). Reliability of all area measurements was excellent (intraclass correlation coefficient [ICC] = 0.994 manual, 0.969 semiautomatic, 0.948 automatic). Reliability of acircularity measurements was 0.879 for manual and 0.606 for automatic.

Conclusion: We identified numerous factors affecting FAZ measurements. These errors confound comparisons across studies and studies examining factors that may correlate with FAZ measures.

Translational Relevance: Using FAZ measurements as biomarkers for disease progression requires assessing and controlling for different sources of error. Not correcting for ocular magnification can result in significant inaccuracy in FAZ measurements, while choice of segmentation method affects both repeatability and accuracy.
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http://dx.doi.org/10.1167/tvst.6.3.16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5469394PMC
June 2017