Purpose:
To demonstrate that RNFL defects can be imaged with optos p200 C, and to determine the prevalence of such defects and determine whether serial imaging is helpful.
Methods:
A prospective study of images from 500 consecutive patients seen from Jan to Oct in 2010 in a private practice setting. A scale of assessing RNFL defects was established: Category (C) 1: defects that were no wider than retinal veins and that did not fan out towards the periphery were classified as likely physiological ("slits"). C2-5: Pathological ("true") defects, were wider than retinal veins, and did fan out towards the periphery (C2: subtle focal defects, up to C5: profound focal and widespread.) SD OCT and GDx as well as 24-2 SS VF and disc assessment were used to confirm the Dx. Previous optos images (available in 290 patients) were also reviewed, for progression.
Results:
434 of the 1000 eyes reviewed had RNFL defects: 380 were C1 (slits). In 40 of these, confident placement into C1 (and not C2) was quite difficult. 24 were C2 (subtle) and 30 were C3-5 (well defined). In C3-5, all eyes showed defects on either OCT, GDx or VF. In C2, 50% had corresponding defects. 21 of the eyes in C2-5 had slits as well as true defects (see image). Follow-up optos imaging was available in 24 of the eyes with true defects; 4 demonstrated apparent progression. These 4 eyes were in 3 patients who reported good compliance with drops. 2 of these eyes initially showed RNFL bundle defects with sharp borders; the borders became less well defined over follow up. In C1 eyes, no slits appear to have progressed.
Conclusions:
RNFL defects can be imaged with optos p200C. Slits were far more common than true defects. GDx, OCT and VF defects showed a positive correlation with increasing RNFL defect severity. All slits were stable on serial imaging; some eyes with true defects progressed. As with fundus photography, serial imaging with optos has clinical utility.
Keywords: nerve fiber layer • imaging/image analysis: clinical • retina