Abstract
Purpose:
To determine if the patients enrolled in LOVIT 2 have greater visual ability at baseline than the patients enrolled in LOVIT. The LOVIT RCTs were conducted to evaluate the outcomes of different models of outpatient LVR provided by the Department of Veterans Affairs. Both RCTs included patients with macular diseases; habitual visual acuity (better-seeing-eye) <20/100 and >20/500 (LOVIT), best-corrected visual acuity (better-seeing-eye) VA <20/50 and >20/200 (LOVIT 2).
Methods:
Rasch analysis with Andrich rating scale model was performed on VA Low Vision Visual Functioning Questionnaire-48 responses at baseline for LOVIT and LOVIT 2 participants combined to look for evidence of study-related DIF, and to compare measures for different functional domains of visual ability (overall, reading, mobility, visual motor and visual information processing).
Results:
Mean habitual visual acuity (better-seeing-eye) of LOVIT patients was 1.1 logMar SD (0.2). Mean best-corrected visual acuity (better-seeing-eye) of LOVIT 2 patients was 0.6 logMAR (SD 0.2). LOVIT 2 participants have significantly more visual ability in all areas except mobility (p<.001 for overall, reading, visual motor and visual information processing). There is agreement between LOVIT and LOVIT 2 item measures (no uniform DIF). However, there is some significant study-dependent non-uniform DIF with LOVIT 2 estimates nosier than LOVIT estimates.
Conclusions:
Patients in LOVIT 2 have greater visual ability at baseline than patients in LOVIT.