Abstract
Purpose :
To investigate cone mediated function and disease progression in patients with Retinitis pigmentosa (RP) using full-field electroretinogram (ffERG) and pattern electroretinogram (PERG). The results were correlated with visual acuity (VA) and ocular coherence tomography (OCT)
Methods :
Clinical records for RP patients undergoing repeat electrophysiology from 2008-2018 were reviewed. Data including age, gender, molecular genetic results, follow-up, and VA were recorded. ffERG (30Hz flicker amplitude, latency and cone fused flicker amplitude(FFA)) and PERG (P50 and N95) results were collected. Macular OCT assessed the linear extent of retina with preserved outer retinal layers (macular island(MI)), outer segment height and central macular thickness (CMT) used the average thickness of the ETDRS map from macular OCT volume
Results :
126 eyes from 63 patients (30 males, mean age 35 range 3-76) were included. Mean duration between visits was 3 years (range 1-9). The mean initial VA was 0.29 ± 0.37 LogMAR and mean change in VA was 0.24 ± 0.28 LogMAR. 15.8% of eyes had macular edema. Mean CMT on the first and last visit was 273.7 ± 55.3 µm and 279.9 ± 51.6 µm respectively. The mean change in fused flicker amplitude was -6.2 ± 10.6 µV in right eye (RE) and -7.4 ± 12.9 µV in left eye (LE) with global cone function decreasing annually by 18.6%. The percentage change in FFA in RE (r=0.55,P<0.01) and LE (r=0.53,P<0.01) correlated with VA. The percentage change in 30Hz flicker amplitude in RE (r=0.62,P<0.01) and LE (r=0.53,P<0.01) and change in latency in RE (r=0.56,P<0.01) and LE (r=0.43,P<0.01) correlated with change in VA.
PERG P50 and N95 (15 and 30 degrees) reduced by 41%, 31% and 42%, 32% respectively. The percentage change in PERG P50 (ρ=0.46,P<0.05) and N95 (ρ=0.31,P<0.05) correlated with VA. The mean MI length was 3701 µm at first and 3516 µm at last visit. Mean height of outer segment on OCT was 51.5 µm at first and 47.6 µm at last visit. The annual rate of shortening and thinning was 4.8% and 4.4% respectively. The MI showed a correlation with VA in RE (r=0.256, P<0.05) and LE (r=0.46, P<0.05)
Conclusions :
Visual function parameters including VA, ffERG, and PERG correlated with OCT measures. This study identified the decline in cone function. The change in these structure and functional measures will assist in planning therapeutic interventions
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.