Purpose:
To evaluate the relationship between reading performance, assessed by psycophysical visual tests, and vision-related quality of life (VRQOL) scores, assessed using the National Eye Institute Visual Function Questionnaire (NEI-VFQ25), in patients with Stargardt disease (STGD).
Methods:
16 consecutive patients with STGD underwent psychophysical testing and microperimetry (MP1, Nidek Technologies, Padova, Italy).
Results:
Mean ETDRS visual acuity was 1.02 (± 0.31) logMAR. One patient with bilateral visual acuity of 5 letters at 2 meters was unable to perform any psycophysical test. Mean Pelli-Robson contrast sensitivity was 18.9 (± 9.6) letters. Using MNREAD charts, mean reading speed was 50 words/minute (1.7 ± 0.29 log), reading acuity was 1.0 (± 0.26) logMAR and critical print size was 1.17 (± 0.26) logMAR. Central 2 degrees and central 4 degrees mean values of fixation stability were 40% (± 23%) and 73% (± 24%) respectively. NEI VFQ-25 scores are presented in the figure.The highest correlation with VRQOL was reached by MNREAD reading acuity (r=-0.73), followed by MNREAD reading speed (0.72), mean REX reading speed (0.66), ETDRS visual acuity (0.64) and Pelli-Robson contrast sensitivity (0.61). There was a statistically significant difference between correlation coefficients of MNREAD reading acuity and ETDRS visual acuity (p<0.001). The relationship between fixation stability and VRQOL was poor (r= 0.36); however, fixation was unstable in many subjects.
Conclusions:
Patients with STDG showed unstable fixation and poor to moderate reading performance. Reading ability assessed with MNREAD charts showed a stronger association with VRQOL scores compared to other psychophysical measures, such as visual acuity and contrast sensitivity threshold for letters (Pelli-Robson) or continuous text (REX charts). This may be due to the sensitivity of reading to several factors, including scotoma size and depth.Psychophysical visual tests and VRQOL assessement could help to guide rehabilitation strategies and to monitor the possible benefits of future treatments in patients with STGD.
Keywords: quality of life • reading • low vision