Adjustable glasses

Self-adjustable spectacles provide ametropic patients with vision comparable to that achieved with standard spectacles selected on the basis of autorefraction performed by a trained eye care provider, said Sang Chul Yoon MD, Yonsei University College of Medicine, Seoul, Republic of Korea. “There are 135 million people worldwide who are visually impaired due to uncorrected refractive error and most of them live in developing countries. Eyeglasses with adjustable lens power can be an effective solution for the correction of refractive in resource-limited settings,” Dr Yoon told an Orbis session at the XXXIII Congress of the ESCRS in Barcelona, Spain. He presented the findings of a study which compared the refractive accuracy and quality of vision of conventional eyeglasses with two different types of self-adjustable glasses, the Focusspec® that uses fluid-filled lens technology and the Childvision,®, that used two sliding lenses. VISUAL ACUITY RESULTS The prospective study included 13 patients with a mean age 28 years whose eyes had a spherical refractive power ranging from -1.5 D to -5.0D measured by auto-refractor. All of the patients underwent vision testing and autorefraction while wearing the two types of self-refracted self-adjustable eyeglasses, and conventional glasses. Dr Yoon and his associates found no significant difference between the Snellen visual acuity achieved with the Focusspec® (1.09) and Childvision™ (1.11) self-adjustable glasses showed and the conventional glasses (1.18) (p=0.058). The mean spherical equivalent when measured by lensometer was lower in the Focusspec (-3.19D) and Childvision (-3.39D) and conventional glasses (-2.64D) (p<0.001). However, there was no significant difference between spherical equivalent of self-adjustable glasses whether adjusted by the patient or in accordance with actual eye measurement performed with an auto-refractor (p=1.000). In terms of contrast sensitivity, there was no statistically significant difference between the liquid-filled Childvision spectacles and conventional spectacles. However, there was a significant difference for multiple spatial frequencies (1.5, 3, 6 cpd) between the Focusspec® and conventional glasses. Some of the other problems that remain with self-adjustable lenses include limited optic zone induced astigmatism and difficulties with optical centration of the glass lenses with respect to the eye. “Both types of self-adjustable glasses provided decent visual acuity and similar spherical equivalent judging by the result of automated refractor. And despite the fact that there are certain aspects that have to be improved, self-adjustable glasses can be an to conventional glasses where refraction by trained eye care provider is not available,” Dr Yoon concluded. C/O Kyoung Yul Seo: seoky@yuh.ac (co-author)