Abstract
Purpose: :
To investigate central vision parameters of visual acuity, color-vision discrimination and retinal function assessed by multifocal electroretinogram (mfERG) in patients with advanced retinitis pigmentosa (RP).
Methods: :
A group of 15 patients with advanced RP (21 eyes; 10 males) aging from 13 to 58 (34±14.4) years was prospectively studied. Inclusion criteria were: informed consent, VA ≥20/200, non-detectable full-field ERG, absence of previous ocular surgery and absence of nystagmus. Visual acuity (VA) was measured in each eye using a retro-illuminated ETDRS optotype chart for distance and noted in logMAR. Color discrimination was determined by the Farnsworth Munsell 100-Hue test monocularly. Central retinal function was assessed by mfERGs recorded from 103 retinal locations within the central 25° with VERIS Science TM 5.1.2 Imaging System. Correlations between VA and color discrimination or mfERG central 5° amplitudes were analyzed by Pearson correlation. Statistical significance was set at P≤0.05.
Results: :
VA ranged from 0.0 to 0.9 logMAR (mean = 0.3 ± 0.2). Six eyes (28%) presented average chromatic discrimination (total error score 17-100) and 15 eyes lower discrimination (total error score>100). Among the 12 patients with lower discrimination, 3 patients (4 eyes) presented tritan defects and the remaining (9 patients -11 eyes) showed diffuse defects. There was a positive correlation between the visual acuity and chromatic discrimination total error score (r = 0.737, P = 0.000139).Reduced mfERG amplitudes in the central 5º were found in all tested eyes (mean: 4.8 ± 2.9 nV/degree2) when compared to age norms from our own lab. P1 latency delay was detected in 4 (19%) eyes (mean: 30.5± 8.5ms). There was a negative correlation between VA and mfERG amplitude in the central 5° (r =- 0.705, P = 0.000755).
Conclusions: :
Severe abnormalities were found in color discrimination and mfERG in this cohort of advanced RP patients. These findings were correlated with visual acuity loss. These results can be used to follow and to monitor the progression of the disease and for future therapeutic interventions.
Keywords: retinitis • electrophysiology: clinical • color vision