Abstract
Purpose :
This observational pilot study evaluates clinically meaningful outcomes and improvements in patient abilities after low vision rehabilitation (LVR) delivered via a mobile clinic. While studies have assessed the outcome of LVR in private clinic and hospital settings, this is the first to examine a mobile clinic delivery model.
Methods :
Legally blind patients (per U.S. Social Security standards) scheduled for a LVR exam on the New England Eye On Sight Mobile Clinic enrolled in this study (n=15, enrollment ongoing). The Activity Inventory (AI) was administered prior to LVR and three months post LVR. Patients received visual assistive equipment, occupational therapy, rehabilitation therapy, and orientation and mobility instruction appropriate for usual care. Rasch analysis was performed to generate person scores (overall visual ability) from AI data. Change scores (differences in visual ability pre and post LVR) were calculated and used to determine minimum clinically important difference (MCID) and Cohen’s d coefficient (d) of observed changes. MCID was calculated for each patient from the ratio of the change score to 1.96 standard errors of the estimated change. For all patients, d was calculated from the ratio of the mean change score to the standard deviation of the change score.
Results :
Patients recruited for this study had a median age of 70.5 years (range 21-92). The majority of patients experienced moderate to severe visual acuity loss (median LogMAR acuity 1.04), and severe contrast sensitivity loss (median MARs contrast sensitivity of 0.72). Of those enrolled, 8 received their first LVR exam on the mobile clinic.
Nearly all patients (n=12) demonstrated MCID in overall visual ability, with a median change score of 0.73 logits. MCID were also noted in the domains of reading (n=8), visual information (n=3), and visual motor (n=2). Additionally, nearly half of the patients demonstrated improvements in activities of daily living in and outside the home per MCID criterion. The largest effect sizes were noted in overall visual ability (d=1.94) and reading (d=0.71).
Conclusions :
The majority of patients presenting to the mobile clinic for LVR demonstrated clinically meaningful differences in overall visual ability, with a large median effect size close to 2 SD. From this pilot study, it appears that delivery of LVR via mobile clinic may have similar outcomes to those reported in other outpatient settings.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.