High Resolution Imaging of Inner Retinal Microcystic Changes in Glaucoma

Abstract

Purpose : To report on the morphology and longitudinal changes of inner nuclear layer microcysts in a primary open angle glaucoma cohort studied with adaptive optics scanning light ophthalmoscopy (AOSLO).

Methods : Thirty-four eyes of 20 primary open angle glaucoma patients (10 females, 10 males) were imaged with simultaneous confocal and non–confocal split-detection AOSLO in reflectance using 790 nm light. Mean age (±SD) was 65±14 ranging between 22 - 85 years old. All patients were participants in a phase Ib recombinant human nerve growth factor clinical trial (clinicaltrials.gov #NCT02855450) and were imaged at different time points during the 32-week long trial, at least once. Microcysts were manually traced using Adobe Photoshop (Adobe Systems, Inc., San Jose, CA) and their individual areas were computed using a custom algorithm implemented in MATLAB (The Mathworks, Inc., Natick, MA). Retinal optical coherence tomography (OCT; Cirrus, Carl Zeiss Meditec, Dublin, CA) volumetric scans and Humphrey visual fields were collected as part of the clinical trial and analyzed for this study.

Results : Individual microcysts were resolved on AOSLO in four patients (6/6 eyes) at the level of the inner nuclear layer following the distribution of papillomacular bundles (sparing the fovea) corresponding to areas of different degrees of visual field loss. A total of 1386 microcysts were manually traced in 4/6 eyes in these patients. Mean area (±SD) was 187±110, 305±179, 307±196 and 833±566 μm². Microcystic changes could only be visualized on OCT in 1/4 patients (1/2 eyes); the one with the largest mean area of microcysts. Follow up over a period of 12 weeks revealed areas in which new microcysts were developing and others were disappearing (Fig. 1).

Conclusions : High resolution AOSLO provides higher sensitivity (20% vs 5%) for detection of microcystic changes which may be missed on conventional imaging techniques, such as OCT. Monitoring these changes can be a useful biomarker for glaucoma progression potentially aiding in the evaluation of new therapies and routine patient care management.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Figure 1. Non-confocal split-detection AOSLO imaging of microcystic changes in a glaucoma patient. The solid- and dashed-lined ellipses denote areas where some microcysts developed and others disappeared, respectively.