Abstract
Purpose: :
The most fundamental goal in glaucoma management is preservation of functional vision. The Assessment of Ability Related to Vision (AARV) is a performance-based measure created to provide a more accurate picture of how patients with visual impairment function in their daily lives. This study was designed to determine the reproducibility of the AARV over time.
Methods: :
A longitudinal, prospective study of glaucoma patients and controls was conducted. Subjects underwent binocular visual acuity and contrast testing, Esterman visual fields, optic nerve assessment, and AARV testing. The AARV consisted of 9 tasks performed binocularly including: reading in dim illumination, recognizing facial expressions, detecting motion, reading signs at a distance, locating objects, ambulating through obstacles, putting a stick into different size holes, dialing using calculators, and matching socks. The total AARV (tAARV) score was calculated by adding the subject's scores for all 9 tasks, with a perfect score of 63 indicating optimal visual function. Baseline results were recorded, and subjects repeated testing at 6 months and 1 year. A mixed effects linear regression was then used to model each outcome as a function of disease state and visit. P<0.01 was considered significant.
Results: :
102 enrolled subjects (81 glaucoma, 21 control) have completed the 6-month visit, and 63 subjects (47 glaucoma, 21 control) have completed the 1-year visit. There were no significant changes in the means for logMAR acuity, field scores, contrast vision, or optic nerve grading over time in either group, although a slight decrease in contrast vision was noted in the glaucoma group (p=0.0384). Mean tAARV scores at baseline, 6 months, and 1 year respectively were as follows: 55.07, 56.95, and 57.88 for controls versus 48.83, 50.32, and 49.85 for glaucoma subjects. The differences in tAARV scores from baseline were statistically significant at 6 months and 1 year in the controls (p=0.0023, p=0.0070 respectively) and at 6 months in glaucoma subjects (p=0.0010). tAARV scores at 1 year were comparable to baseline in glaucoma subjects (p=0.0902).
Conclusions: :
The improvement in tAARV scores over time in controls and glaucoma patients may be due to a slight learning effect but likely is not clinically significant. In the glaucoma group, the learning effect may be counteracted by worsening contrast vision at 1 year. As a reproducible direct measure of visual function, the AARV may serve as a new tool to assist ophthalmologists in their goal of preserving usable vision for their patients.
Keywords: quality of life • clinical research methodology • vision and action