Grading Sphero-Cylinder Spectacle Similarity
Received 3 November 2020
Accepted for publication 3 December 2020
Published 20 January 2021 Volume 2021:13 Pages 23—32
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 2
Editor who approved publication: Mr Simon Berry
Robert W Arnold,1 Joshua S Beveridge,1 Samuel J Martin,1 Nathanael R Beveridge,1 Elise J Metzger,2 Kyle A Smith3
1The Alaska Blind Child Discovery, Anchorage, AK 99508, USA; 2Grace Christian School, Anchorage, AK, USA; 3Kyle Smith, Accurate Vision, Anchorage, AK, USA
Correspondence: Robert W Arnold
The Alaska Blind Child Discovery, Alaska Children’s EYE & Strabismus, 3500 Latouche #280, Anchorage, AK 99508, USA
Tel +1 907 561-1917
Fax +1 907 563-5373
Background: Portable autorefractors can estimate refractive error in remote locations, but sphero-cylinder comparison and donated-spectacle dispensing are not yet simple.
Methods: Normal astigmats determined best corrected acuity, then degraded 1 logMAR (Grade A), 3 logMAR (Grade B), and 6 logMAR (Grade C) to determine limits of astigmatism axis and power at these levels. The cylindrical refraction was vector transformed with J0 on the abscissa and J45 on the ordinate.
Results: Ten subjects produced multiple refractions at the interfaces of Grades A, B, and C representing ovals on the J0 and J45 coordinates. When rotated, the vertical axis represented 45° or 135°, the horizontal long axis was 1.6× the short axis. The size of the ovals positively correlated with cylinder power. Given a target refraction, the comparability of a candidate lens was demonstrated on our interactive database yielding a simple A, B, C, or worse grade for cylinder, spherical equivalent, and pupillary diameter.
Conclusion(s)/Relevance: Inputting a remote autorefraction, pupillary diameter and age as target and a donated spectacle as the candidate with a “B” grade similarity would be expected to attain 20/40 acuity (3 logMAR degrade) if best corrected visual acuity was 20/20. This practical Excel database could facilitate widespread remote lay dispensing of the cylinder as well as spherical spectacles. The grade similarity can also compare refracting tools such as photoscreeners and hand-held autorefractors.
Clinical Trials Registry: NCT04297969.
Keywords: donated recyled spectacles, remote dispensing, portable autorefraction, vision screen validation, forensic optometry
This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution - Non Commercial (unported, v3.0) License. By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms.Download Article [PDF] View Full Text [HTML][Machine readable]