Multifocal electroretinographic responses in sector retinitis pigmentosa.

HEADINGS: Multifocal electroretinography (mfERG) may be useful in the management of sector retinitis pigmentosa (SRP). AIM: To compare multifocal electroretinographic responses in SRP, generalised retinitis pigmentosa (GRP), and healthy controls. METHODS: Eighteen patients with SRP, twelve with GRP, and fifteen controls were included in the study. All participants underwent: complete ophthalmological examination, Humphrey visual field testing, full-field ERG, and mfERG. The mean P1 amplitude, the implicit time (IT), and the mapping of the local responses were evaluated. RESULTS: The mean P1 amplitude was higher in the SRPs than in GRPs (p < 0.001), while it did not differ between SRPs and controls (p = 0.913). In the SRPs, the P1 amplitude in pathologic areas was higher than in the GRPs (p < 0.001). In normal areas, this parameter did not differ from the controls (p = 0.499). Moreover, in the SRPs, no differences in the P1 amplitude and the IT between pigmented and non-pigmented areas were found. CONCLUSION: In the present study, the mfERG examination displayed significant differences between sector and generalised RP, showing normal values in sector RP even in pigmented areas. Considering the patients included in this study, SRP seems to represent a favourable variant of the disease, characterised by a limited retinal involvement and apparently mild functional damage. It is still unclear how these results can be extended to other forms of SRP.

Reading Ability and Quality of Life in Stargardt Disease.

PURPOSE: To study the reading performance of patients with Stargardt disease (STGD) and the relationship between clinical vision measurements and vision-related quality of life (VRQOL). METHODS: We studied both eyes of 16 patients with STGD. Each patient was examined for best-corrected visual acuity (Early Treatment Diabetic Retinopathy Study [ETDRS]), reading ability (MNREAD and REX charts), contrast sensitivity (Pelli-Robson charts), fixation study (MP1 microperimeter), and VRQOL (25-item National Eye Institute Visual Function Questionnaire [NEI VFQ-25]). The correlation pattern among these variables was examined and an exploratory factor analysis was used to investigate dimensionality of both visual function and VRQOL. RESULTS: Mean ETDRS visual acuity was about 20/160 (0.9 logMAR). All studied psychophysical measures were highly or moderately correlated with MNREAD reading speed (p<0.05 level). A similar correlation was found between psychophysical measures and VRQOL, which was higher for MNREAD measures of acuity (r = -0.75) and speed (r = 0.74). Accordingly, exploratory factor analysis suggested that a single latent dimension explained most of the variance of vision psychophysical measures as well as of VRQOL. CONCLUSIONS: We propose that reading ability should be assessed in patients with STGD, since we found that both MNREAD reading speed and visual acuity are strong determinants of quality of life. The observed relation between reading ability and VRQOL in STGD suggests that in these patients appropriate low vision rehabilitation can improve both reading performance and consequently VRQOL. Finally, our data support the use of reading speed and visual acuity as important outcome measures for monitoring STGD progression.

Biofeedback rehabilitation of eccentric fixation in patients with Stargardt disease.

PURPOSE: To evaluate the efficacy of biofeedback (BF) microperimetric rehabilitation in patients with Stargardt disease (STGD). 
 METHODS: Eighteen patients with STGD with unstable fixation located in the superior retina and best-corrected visual acuity (BCVA) between 20/100 and 20/320 in the better eye were recruited. All the patients underwent Nidek MP-1 microperimetry and fixation analysis. Twelve patients underwent 8 consecutive BF training sessions of 10 minutes each, performed once a week in the better eye. Six patients did not receive any training and were used as controls. In both groups, BCVA, reading speed, contrast sensitivity, bivariate contour ellipse area (BCEA), and retinal sensitivity were evaluated in the better eye at baseline and after 10 weeks. Paired and unpaired t tests were used as appropriate. 
 RESULTS: In the control group, after the follow-up period, fixation pattern did not show any modification and the other parameters worsened or remained unchanged. On the contrary, the BF group showed significantly improved stabilization of fixation (mean BCEA 68.2% from 5.63°2 to 1.58°2), improved mean BCVA (from 34.00 to 37.67 letters), higher mean reading speed (from 66.67 to 84.00 words/min), higher contrast sensitivity (from 16.33 to 18.75 letters), and improved retinal sensitivity (from 10.68 to 12.29 dB). The comparison of the results obtained in the 2 groups was statistically significant for all the considered parameters except for retinal sensitivity. CONCLUSIONS: Biofeedback rehabilitation with the MP-1 increases quality of vision in patients with STGD, leading to a stabilization of fixation and a consequent improvement of patients' visual function and reading abilities

Reading performance in patients with retinitis pigmentosa: a study using the MNREAD charts.

PURPOSE: To evaluate the relationship between reading performance and severity of disease in patients with retinitis pigmentosa (RP), assessed with routine clinical psychophysical visual tests. METHODS: Seventy-six consecutive patients with RP (145 eyes), with reading acuity of at least 1.6 logMAR (logarithm of the minimum angle of resolution) in at least one eye, were examined. Each patient underwent a complete ophthalmic evaluation, including visual acuity (Early Treatment Diabetic Retinopathy Study [ETDRS] charts), contrast sensitivity (Pelli-Robson charts), visual field perimetry (Humphrey central 30-2 full-threshold program; Carl Zeiss Meditec, Dublin, CA), and a test of reading acuity, critical print size, and maximum reading speed (Minnesota Reading charts [MNREAD]). RESULTS: Reading acuity was 1.0 logMAR or more in the better eye of all but six (92%) patients. Maximum reading speed was better than 100 words per minute in the better eye of 59 (78%) subjects. Moderate to severe reading impairment, defined as reading acuity of 0.4 logMAR or worse, was observed in the better eye of 47 (62%) patients. EDTRS visual acuity of 0.3 logMAR (20/40) or worse was 89% sensitive and 66% specific when used as a criterion to define reading impairment. Contrast sensitivity and visual acuity correlated significantly with all three reading components, whereas mean light sensitivity in the central visual field (6 degrees ) demonstrated a higher correlation with maximum reading speed. The number of years elapsed since the diagnosis of RP was a strong negative predictor of reading performance when clinical visual tests were taken into account, whereas a better reading ability characterized the patients with RP who had a higher level of education. A reduced reading speed with larger print size was found in 30 eyes (21%). This correlated with central light sensitivity, as it was more common among eyes with a mean sensitivity of <10 dB. CONCLUSIONS: The reading performance of most patients with RP is only moderately impaired. It correlates with contrast sensitivity, visual acuity, and visual field. It should be assessed in all cases, as disability can ensue, even when visual acuity is preserved. In patients with RP with poor reading performance, there is little potential for high-magnification devices because visual field constriction affects the reading rate.