Interactive, computer-based, self-reported, visual function questionnaire: the PalmPilot-VFQ.
OBJECTIVE
To evaluate the testing performance, reliability, and validity of a self-administered visual function questionnaire designed for a Palm Pilot in comparison with the interviewer-administered-National Eye Institute Visual Function Questionnaire-25 (NEI-VFQ-25) (interviewer-NEI-VFQ-25) and self-administered-NEI-VFQ-25 (self-NEI-VFQ-25).


METHODS
The interviewer-NEI-VFQ-25 was administered to 135 sequential patients who visited a retina clinic, followed on separate days by the Palm Pilot-Visual Function Questionnaire (PalmPilot-VFQ) and self-NEI-VFQ-25. Rasch analysis of ordinal difficulty ratings for the PalmPilot-VFQ was used to estimate interval measures of perceived visual ability. Reliability was determined by calculating Cronbach's alpha and test-retest intraclass correlation coefficients (ICCs). Concurrent validity was determined by calculating correlations of the PalmPilot-VFQ score with that of a general vision question. For evaluating convergent validity, the PalmPilot-VFQ was compared with the interviewer-NEI-VFQ-25, habitual-correction visual acuity (HCVA), and with two visual analogue scale (VAS) questions. Performance time and testability were compared among the three questionnaires.


RESULTS
Rasch analysis eliminated two items in the PalmPilot-VFQ due to poor-fit statistics. The final items showed internal consistency (Cronbach's alpha=0.89) and test-retest reliability (ICC=0.79), as well as an excellent separation index (3.23 and 4.01) for item parameters with significant concurrent correlation (P<0.0001). On evaluating convergent validity, the PalmPilot-VFQ showed strong correlations with interviewer-NEI-VFQ-25, with the HCVA of the better-seeing eye, and with the VAS questions (P=0.0001). Ninety percent of the 135 patients (HCVA >20/200 in the better-seeing eye) could perform the PalmPilot-VFQ with their habitual correction or high-plus spectacles, but in significantly less time than either interviewer-NEI-VFQ-25 or self-NEI-VFQ-25 (P<0.0001).


CONCLUSIONS
The PalmPilot-VFQ seems to be a reliable, valid, interactive, computer-based, self-administered questionnaire that can be used routinely by physicians to evaluate functional vision disability in populations with a high prevalence of macular disease.
Unver
Y B
YB
Beyoğlu Eye Training and Research Hospital, Istanbul, Turkey. yaprakbanu@yahoo.com
Yavuz
G A
GA
Sinclair
S H
SH
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D034201:Computers, Handheld / Q000592:standards; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires / Q000592:standards*; D014786:Vision Disorders / Q000503:physiopathology*; D055815:Young Adult