Tablet App halometer for the assessment of dysphotopsia

Abstract

Purpose To assess the validity and repeatability of the Aston Halometer. Setting University clinic, United Kingdom. Design Prospective, repeated-measures experimental study. Methods The halometer comprises a bright light-emitting-diode (LED) glare source in the center of an iPad4. Letters subtending 0.21° (∼0.3 logMAR) were moved centrifugally from the LED in 0.05 degree steps in 8 orientations separated by 45 degrees for each of 4 contrast levels (1000, 500, 100, and 25 Weber contrast units [Cw]) in random order. Bangerter occlusion foils were inserted in front of the right eye to simulate monocular glare conditions in 20 subjects (mean age 27.7 ± 3.1 years). Subjects were positioned 2 meters from the screen in a dark room with the iPad controlled from an iPhone via Bluetooth operated by the researcher. The C-Quant straylight meter was also used with each of the foils to measure the level of straylight over the retina. Halometry and straylight repeatability was assessed at a second visit. Results Halo size increased with the different occlusion foils and target contrasts (F = 29.564, P <.001) as expected and in a pattern similar to straylight measures (F = 80.655, P <0.001). Lower contrast letters showed better sensitivity but larger glare-obscured areas, resulting in ceiling effects caused by the screen's field-of-view, with 500 Cw being the best compromise. Intraobserver and interobserver repeatability of the Aston Halometer was good (500Cw: 0.84 to 0.93 and 0.53 to 0.73) and similar to the straylight meter. Conclusion The halometer provides a sensitive, repeatable way of quantifying a patient-recognized form of disability glare in multiple orientations to add objectivity to subjectively reported discomfort glare.

Publication DOI: https://doi.org/10.1016/j.jcrs.2015.05.041
Divisions: Life & Health Sciences > Optometry
Life & Health Sciences > Ophthalmic Research Group
Life & Health Sciences
Life & Health Sciences > Vision, Hearing and Language
Uncontrolled Keywords: Ophthalmology,Sensory Systems,Surgery
Full Text Link:
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2015-11
Accepted Date: 2015-05-01
Submitted Date: 2015-03-10
Authors: Buckhurst, Phillip J.
Naroo, Shehzad A. ( 0000-0002-6373-7187)
Davies, Leon N. ( 0000-0002-1554-0566)
Shah, Sunil ( 0000-0002-5373-5305)
Buckhurst, Hetal
Kingsnorth, Alec
Drew, Tom
Wolffsohn, James S. ( 0000-0003-4673-8927)

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