Purpose
To evaluate the inner segment/outer segment (IS/OS) layer seen on spectral domain optical coherence tomography (SD-OCT) in eyes with macular edema due to central retinal vein occlusion (CRVO).
Methods
In 6 patients with macular edema from CRVO, we compared the IS/OS layer (or ellipsoid zone) using spectral domain OCT (SD-OCT) to the IS/OS layer in the normal fellow eyes. Using a computer-aided manual segmentation technique of the SD-OCT images, we measured the area of absent IS/OS within the raster by means of an “en face” view and the IS/OS thickness in the central subfield.
Results
A total of 10 eyes of 6 patients were graded using the FPRC segmentation protocol. Of the six CRVO eyes with macular edema, four eyes had OCT scans of the normal fellow eye. In the CRVO eyes, mean OCT central retinal thickness was 538 microns (401 - 754um); in the normal eyes, mean central retinal thickness was 250 microns (224 - 270um). In the CRVO eyes, 5 out of 6 eyes had an area of absent IS/OS. The mean area of absent IS/OS was 3.2 mm2 (SD of 3.1mm2) (See Figure 1); in all normal eyes, the IS/OS was intact. In the central subfield, the mean IS/OS thickness was 18.2mm in the study eyes and 35.3mm in the normal eyes.
Conclusions
We report the area of absent IS/OS and IS/OS thickness in CRVO eyes with significant macular edema. In our sample, IS/OS thickness in CRVO eyes was 51% of the IS/OS thickness of the normal eyes. The area of absent IS/OS in eyes with CRVO was not found in the normal eyes and may represent a valuable means of assessing photoreceptor damage.
Keywords: 749 vascular occlusion/vascular occlusive disease •
550 imaging/image analysis: clinical •
505 edema