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Assessment of Downward Deviation of Progressive Addition Lenses in a Myopia Contorol Study

Okayama University Med School, Ophthalmology, Okayama, Japan

Commercial Relationships: C. Nakatsuka, None; S. Hasebe, None; F. Nonaka, None; H. Ohtsuki, None.

Grant Identification: Support: Grant–in–Aid for Sceientific Research (B), No.15390532

Abstract

Purpose: To determine how downward deviation of progressive addition lenses reduces its effectiveness in school children.

Methods: In 46 of 95 participants (age range: 6–12 years) in a randomized clinical trial of myopia control in Japanese schoolchildren, progressive addition lenses (MC lens, Sola Inc., USA) were prescribed accrording to a routine spectacle fitting protocol at the initial consultation. At the second consultation after 6 months of using the spectacles, the alignment of the lenses in relation to the eyes was captured with a digital still camera, Cyber–shot 2.0 (Sony, Japan), that was placed on a level plane involving the rotational points of the eyes, while leaving the head posture free. The vertical distance of the fitting points of the progressive addition lenses from the corneal light reflex was measured with NIH image.

Results: The fitting points of the lenses deviated downward by 3.7±2.2 mm (mean±SD, range: –1.4 to 11.0mm) from their ideal positions. In 25% of the subjects, the deviation was more than 5.0mm. The 95% confidence limits of agreement in this measurement was ±0.3mm.

Conclusions: Downward deviation of the progressive addition lenses is a crucial factor that reduces their hypothetical effectiveness in myopia control. This deviation would cause few symptoms in schoolchildren because of their ample accommodation faculty. To obtain full effectiveness of the lenses, the routine spectacle fitting criterion for presbyopic patients is not sufficient, and frequent verification of the proper lens alignment based on image processing analysis is probably required.

Keywords: myopia • refractive error development • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials

© 2004, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved. For permission to reproduce any part of this abstract, contact the ARVO Office at arvo{at}arvo.org.