Comparing predicted magnification in tablet screens to patient preferred magnification in low vision patients

Title Comparing predicted magnification in tablet screens to patient preferred magnification in low vision patients
Author, Co-Author Karen Squier, Bianca Guardiola
Topic Low Vision
Year
2016
Day
Thursday
Program Number
165140
Room
Ballroom A-B
Affiliation
Southern College of Optometry
Abstract

Purpose: The aim of this study was to determine whether the predicted magnification of a tablet screen correlates with the actual preferred magnification of a tablet screen in low vision patients.

Introduction: The technological age has brought with it computers, tablets, and smart phones and are now a resource for the visually impaired. This study aimed to determine whether the actual preferred magnification of the low vision patient while using a tablet correlates with the predicted magnification.

Methods: 40 Patients were screened at The Alfred and Sarah Rosenbloom Center on Vision and Aging and the Chicago Lighthouse. Patients were divided into four categories based on their visual field presentation: central visual acuity loss, visual field constriction, general blur and normal sighted individuals.

Best corrected near visual acuities were recorded with working distance. Patients used an Apple iPad ® and instructed on how to magnify the print using the method of pinching their thumb and forefinger on the screen and then instructed to magnify the print until it was the preferred size for them. The size of the letter was measured, as well as the distance of the tablet from the patient’s spectacle plane. Both predicted magnification and patient preferred magnification were calculated in comparison to 1M in M notation.

Results: ANOVA indicated that there was a significant difference between predicted magnification and patient preferred magnification. (F=23.88, p < 0.001). There was a significant difference between the 3 low vision groups and the control (F=5.62, p = 0.003). The central vision loss group (p = 0.016) and the peripheral vision loss group (p = 0.001) differed significantly from the control group, while the general loss group did NOT (p = 0.3).

Conclusions: Overall all groups patient’s preferred magnification was significantly greater than what was predicted based on their visual acuity.

Affiliation of Co-Authors Illinois College of Optometry
Outline