Lyne Racette

Comparison of Standard Automated Perimetry, Short-Wavelength Automated Perimetry, and Frequency-Doubling Technology Perimetry to Monitor Glaucoma Progression.

AbstractDetection of progression is paramount to the clinical management of glaucoma. Our goal is to compare the performance of standard automated perimetry (SAP), short-wavelength automated perimetry (SWAP), and frequency-doubling technology (FDT) perimetry in monitoring glaucoma progression.Longitudinal data of paired SAP, SWAP, and FDT from 113 eyes with primary open-angle glaucoma enrolled in the Diagnostic Innovations in Glaucoma Study or the African Descent and Glaucoma Evaluation Study were included. Data from all tests were expressed in comparable units by converting the sensitivity from decibels to unitless contrast sensitivity and by expressing sensitivity values in percent of mean normal based on an independent dataset of 207 healthy eyes with aging deterioration taken into consideration. Pointwise linear regression analysis was performed and 3 criteria (conservative, moderate, and liberal) were used to define progression and improvement. Global mean sensitivity (MS) was fitted with linear mixed models.No statistically significant difference in the proportion of progressing and improving eyes was observed across tests using the conservative criterion. Fewer eyes showed improvement on SAP compared to SWAP and FDT using the moderate criterion; and FDT detected less progressing eyes than SAP and SWAP using the liberal criterion. The agreement between these test types was poor. The linear mixed model showed a progressing trend of global MS overtime for SAP and SWAP, but not for FDT. The baseline estimate of SWAP MS was significantly lower than SAP MS by 21.59% of mean normal. FDT showed comparable estimation of baseline MS with SAP.SWAP and FDT do not appear to have significant benefits over SAP in monitoring glaucoma progression. SAP, SWAP, and FDT may, however, detect progression in different glaucoma eyes.

Prediction accuracy of a novel dynamic structure-function model for glaucoma progression.

PURPOSE To assess the prediction accuracy of a novel dynamic structure-function (DSF) model to monitor glaucoma progression. METHODS Longitudinal data of paired rim area (RA) and mean sensitivity (MS) from 220 eyes with ocular hypertension or primary open-angle glaucoma enrolled in the Diagnostic Innovations in Glaucoma Study or the African Descent and Glaucoma Evaluation Study were included. Rim area and MS were expressed as percent of mean normal based on an independent dataset of 91 healthy eyes. The DSF model uses centroids as estimates of the current state of the disease and velocity vectors as estimates of direction and rate of change over time. The first three visits were used to predict the fourth visit; the first four visits were used to predict the fifth visit, and so on up to the 11th visit. The prediction error (PE) was compared to that of ordinary least squares linear regression (OLSLR) using Wilcoxon signed-rank test. RESULTS For predictions at visit 4 to visit 7, the average PE for the DSF model was significantly lower than OLSLR by 1.19% to 3.42% of mean normal. No significant difference was observed for the predictions at visit 8 to visit 11. The DSF model had lower PE than OLSLR for 70% of eyes in predicting visit 4 and approximately 60% in predicting visits 5, 6, and 7. CONCLUSIONS The two models had similar prediction capabilities, and the DSF model performed better in shorter time series. The DSF model could be clinically useful when only limited follow-ups are available. (ClinicalTrials.gov numbers, NCT00221923, NCT00221897.).

Comparison of matrix frequency-doubling technology perimetry and standard automated perimetry in monitoring the development of visual field defects for glaucoma suspect eyes

Background Perimetry is indispensable for the clinical management of glaucoma suspects. Our goal is to compare the performance of standard automated perimetry (SAP) and Matrix frequency-doubling technology (FDT) perimetry in monitoring the development of visual field (VF) defects in glaucoma suspect eyes. Methods Longitudinal data of paired SAP and FDT from 221 eyes of 155 glaucoma suspects enrolled in the Diagnostic Innovations in Glaucoma Study or the African Descent and Glaucoma Evaluation Study were included. All eyes had glaucomatous optic neuropathy or ocular hypertension, but normal SAP and FDT results at baseline. The development of glaucomatous VF defects was defined as the presence of a cluster of ≥ 3 (less conservative) or ≥ 4 (more conservative) locations confirmed on ≥ 2 additional consecutive tests. Risk factors for the development of VF defects were analyzed by COX proportional hazard models. After conversion into common logarithmic units, the rates of change of global VF indices were fitted with linear mixed models. Results FDT detected more eyes that developed VF defects than SAP using the less conservative criterion, and no significant difference was observed using the more conservative criterion. For those eyes detected by both SAP and FDT, FDT detected the development of VF defects either earlier than SAP or simultaneously in most cases. Baseline structural measurements were not significantly associated with an increased risk for the development of glaucomatous VF defects on either SAP or FDT. Older age was significantly associated with the development of VF defects on FDT but not on SAP. Both SAP and FDT detected a progressing worsening trend of pattern standard deviation over time with a similar rate of change between these test types. Conclusions Matrix FDT would be useful to monitor the onset of VF defects in glaucoma suspects and may outperform SAP in the early stage of glaucomatous VF damage.

Retinal thickness estimation from SD-OCT macular scans

Glaucoma, a leading cause of blindness worldwide, can be detected using retinal thicknesses from spectral-domain optical coherence tomography (SD-OCT) scans of the macula. We calculate the desired thickness maps as the distance between the inner-limiting membrane (ILM) and retinal pigmented epithelium (RPE) of the retina. To delineate these two layers, we use a set of two deformable open surfaces that are driven by intensity contrast, while preserving their shape and topology properties, i.e. local surface smoothness and inter-surface distance smoothness. To evaluate our method, qualified graders manually segmented 30 random sections from 20 OCT image stacks, in triplicate; we make comparisons with obtained ground-truth and the clinically tested Heidelberg Spectralis segmentation. We show the superiority of our method with respect to accuracy and average execution time (~7 secs), validating it as a clinical tool.

Racial differences in primary open-angle glaucoma: more than meets the eye

Glaucoma is one of the leading causes of blindness and visual impairment worldwide. It is an age-related optic neuropathy in which the degeneration of the retinal ganglion cells and their axons results in a distinct appearance of the optic disc and a characteristic pattern of visual field loss [1]. Primary open-angle glaucoma (POAG) is one of the most common forms of glaucoma. It is estimated that POAG affects approximately 33 million people worldwide [2] and 2.5 million people in the USA [3]. People of African descent are disproportionately affected by POAG [4]. In certain age groups, the prevalence of POAG is estimated to be up to six-times higher in people of African descent compared with people of European descent. POAG is more likely to result in irreversible blindness, appears approximately 10 years earlier and progresses more rapidly in people of African descent compared with people of European descent [5,6]. The reasons underlying the higher prevalence of POAG in people of African descent are not yet known. Health disparities are recognized as a serious problem in the USA. One of the stated goals of the 1999 Secretary’s Council on Health Promotion and Disease Prevention Objectives in the US Department of Health and Human Services was to eliminate disparities in health status among racial and ethnic populations in the USA. Several federal agencies, including the US Congress and the NIH, have included the reduction and elimination of health disparities in their respective strategic plan. The NIH National Center on Minority Health and Health Disparities was established in 2000 by the passage of the Minority Health and Health Disparities Research and Education Act. In 2010, this NIH center transitioned to a fully-fledged institute, the National Institute on Minority Health and Health Disparities under the Patient Protection and Affordable Care Act (PPACA). The NIH defines health disparities as “the difference in the incidence, prevalence, mortality and burden of diseases and other adverse health conditions that exist among specific population groups in the United States.” Other definitions of health disparities have been put forth, including that of Margaret Whitehead (University of Liverpool, Liverpool, UK), a noted public health researcher. She defined health disparities as “differences in health that are not only unnecessary and avoidable but, in addition, are considered unfair and unjust” [7]. The definition put forth by the NIH encompasses all health differences between populations, while Whitehead’s definition focuses on those differences that are avoidable, such as access to healthcare. Taken together, these two definitions highlight the multifactorial nature of health disparities. Therefore, the reduction and elimination of health disparities requires a multi faceted approach focused on biological, social and economic factors. The recent passage into law of the PPACA, also referred to as Obamacare, could have a significant impact on reducing avoidable health differences in Racial differences in primary open-angle glaucoma: more than meets the eye