Abstract
Purpose:
Retinitis pigmentosa (RP) is an inherited retinal degeneration that affects the night and peripheral vision initially and affects the central vision at a later stage. However, sometimes the center vision can be affected by changes in the macular area like epiretinal membranes, vitreomacular traction, atrophic lesions at the fovea and cystic changes. Several studies have attempted to measure the central point thickness (CPT) and central subfield thickness (CSF) in RP but none of the studies have looked at the macular volume (MV). This study aims at measuring the macular thickness and volume in patients with retinitis pigmentosa with and without macular changes using the Spectralis spectral-domain optical coherence tomography (SD-OCT).
Methods:
This was a retrospective chart review where all patients with RP in an inherited diseases practice at a University were identified (n=97). Patients with all genetic types of RP and Usher syndrome were included. All patients with glaucoma, optic atrophy, patients with poor quality of scans were excluded. Finally, the SD-OCT scans from 65 patients were included. The CPT and CSF (1mm) were defined as macular thickness. For the macular volume, 1mm and 3mm circles of ETDRS segments were used. The measurements were made for both eyes and averaged. It was also correlated with best-corrected visual acuity.
Results:
The mean CPT was 238.4μ and the mean CSF was 271.1μ. The macular volume in the central 1mm of the ETDRS segments was 0.2mm3 and the central 3mm was 2.1mm3. There was a difference between retinas with atrophic lesions vs cystic changes, although it was variable.
Conclusions:
The macular volume in conjunction with macular thickness is an excellent tool to monitor patients with retinitis pigmentosa. More importantly, it will also serve as one of the measurements to monitor the response of cystic changes in RP to topical or systemic carbonic anhydrase inhibitors in future studies.
Keywords: 696 retinal degenerations: hereditary •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
494 degenerations/dystrophies