Relationship between difficulty in performing daily activities and clinical measures of visual function in patients with retinitis pigmentosa
J. P. Szlyk, G. A. Fishman, K. R. Alexander, B. I. Revelins, D. J. Derlacki and R. J. Anderson
Department of Ophthalmology and Visual Sciences, UIC Eye Center, University of Illinois at Chicago, USA.
OBJECTIVES: To assess the level of perceived difficulty experienced by
patients with retinitis pigmentosa (RP) in the performance of everyday
activities and to determine the correlation between patients' self-reported
difficulty and clinical measures of visual function. METHODS: One hundred
sixty-seven patients with typical RP and Usher syndrome type 2, with a wide
range of disease severity, rated their difficulty in the performance of 33
activities. We obtained data on visual acuity and visual field area for all
patients, and electroretinogram (ERG) recordings on a subgroup of 49 of
these patients. Results from the questionnaire were analyzed with factor
analysis, and patients' self-reports were compared with their clinical data
using correlational analyses and multiple regression. RESULTS: The
patients' questionnaire responses clustered into 6 factors: activities
involving central vision, miscellaneous activities (no discernible common
factor), activities related to mobility, driving, negotiating steps, and
eating meals. Of the clinical tests, visual acuity was most strongly
related to the patients' ratings of their difficulty in performance. Visual
field area also was related to patients' self-assessments but not as
strongly as visual acuity. Because visual field area and the ERG measures
were correlated, adding ERG information did not improve predictability.
CONCLUSIONS: In patients with RP, perceived difficulty in performing common
tasks was most strongly related to level of visual acuity and visual
fields. Although certain ERG amplitude measures did show positive
correlations with some self-reported activities, overall, the ERG amplitude
measures showed the least relationship with patients' self-reports. Our
results provide insight into RP patients' perceived difficulties in
performing everyday activities and the clinical measures of visual function
that most highly correlate with these difficulties.
