Abstract
Purpose :
The natural history of retinitis pigmentosa (RP) is known to vary across different inheritance patterns and across genetic etiologies. Two large groups of disease include RP caused by mutations in ciliary genes and RP caused by mutations in non-ciliary genes. This study aims to determine differences in disease progression in patients with mutations in ciliary and non-ciliary genes using spectral-domain optical coherence tomography (SD-OCT) and 30Hz flicker response in full-field electroretinograms. Study of the natural history of disease is critical to improve understanding and may guide clinical therapies by demonstrating which will require more aggressive and earlier intervention.
Methods :
Retrospective chart review was performed of patients with genetically confirmed diagnoses of RP. SD-OCT images were obtained from 285 patients, 188 of whom were found to have mutations in ciliary genes. 30Hz flicker amplitudes were obtained from 69 patients with mutations in ciliary genes and 33 patients with mutations in non-ciliary genes. SD-OCT images were evaluated through measurements of ellipsoid zone (EZ) length and central foveal thickness (CFT) using the built-in caliper tool on the Spectralis HRA+OCT. The amplitudes of the 30Hz flicker electroretinograms were collected from a Diagnosys Espion Electrophysiology System.
Results :
Longitudinal analysis of SD-OCT images revealed that the EZ deteriorated at a mean rate of 26.4µm/year in the ciliary gene cohort as compared to 15.7µm/year in the non-ciliary gene cohort. Measurement of CFT revealed a mean decrease of 0.7µm/year in the ciliary gene cohort as compared to 1.06µm/year in the non-ciliary gene cohort. 30Hz flicker amplitude decreased at a mean rate of 1.4µV/year in the ciliary gene cohort and 0.8µV/year in the non-ciliary gene cohort. The mean follow-up period for SD-OCT images was 4 years, while the mean follow-up period for 30Hz flicker measurements was 2.2 years.
Conclusions :
Our study suggests that on average, RP due to mutations in ciliary genes may progress faster than RP due to mutations in non-ciliary genes as seen by EZ measurements and 30Hz flicker amplitudes. Therefore, patients with ciliary gene mutations may require more aggressive and earlier therapeutic intervention, and EZ line measurements and 30Hz flicker amplitudes may serve as viable outcome measurements for future clinical trials.
This is a 2021 ARVO Annual Meeting abstract.