OUTER NUCLEAR LAYER THINNING IN PACHYCHOROID PIGMENT EPITHELIOPATHY

To compare the average thicknesses of central inner retinal layers in eyes with pachychoroid pigment epitheliopathy (PPE), with uncomplicated pachychoroid (UCP), and of healthy subjects.

Medical records of patients with PPE and UCP were retrospectively reviewed. Twenty-nine eyes with foveal PPE, 30 eyes with UCP, and 29 eyes of healthy subjects were included. Spectral-domain optical coherence tomography with enhanced depth imaging was used for all optical coherence tomography scans. Mean central inner retinal layer thicknesses were measured in 1-mm-diameter circle with Spectralis automated segmentation software and compared between groups.

The outer nuclear layer (ONL) and the sum of the outer plexiform layer and ONL were significantly thinner in the PPE group than the UCP and control groups (ONL: P < 0.001, P < 0.001; outer plexiform layer + ONL: P = 0.002, P = 0.002, respectively). There was no significant difference between groups regarding thickness of the outer plexiform layer and other inner retinal layers. Eyes with UCP and normal eyes did not differ.

The ONL is thinner in eyes with PPE. The degenerative process of pachychoroid spectrum diseases may begin with retinal pigment epithelium alterations before subretinal fluid accumulation. The PPE lesions, commonly seen above pachyvessels, may be an indicator of photoreceptor apoptosis.