Average Acuity-Based Outcomes Improved With Eyeglasses Using 0.05D Steps

Eyeglasses manufactured and refraction performed using 0.05D steps were able to improve average visual acuity-based outcomes, according to a study published in Clinical & Experimental Optometry. These glasses were also more often preferred by participants compared with the more traditional 0.25D steps.

Refractive error that is uncorrected is just 1 common cause of visual impairment. Glasses are most often used to correct refractive errors and are traditionally made with 0.25D steps, which is approximately a 1-line decrease on a standard visual acuity chart. The duochrome test has been used to verify the final refraction. The aim of this investigation was to evaluate whether 0.05D steps were able to improve the proportion of those who can achieve a subjective end point of red-green equality on the duochrome test. This article also aimed to evaluate whether the 0.05D-step glasses offered vision performance benefits compared with glasses made with 0.25D steps.

There were 2 studies conducted to investigate the effectiveness of 0.05D steps. The first study included adults aged 18 to 30 years who were myopic with a subjective refraction range. Participants were included in the second study if they were healthy adults aged 18 to 45 years, were willing to refrain from using soft contact lenses, and were myopic. Participants were excluded from both studies if they had any ocular or medical disease that could affect their vision, history of eye surgery or trauma, or any history of corneal refractive surgery.

The first study featured a single visit to the Beijing Institute of Ophthalmology in Beijing, China. All participants had 2 drops of 1% cyclopentolate in each eye 10 minutes apart. A duochrome test was used to determine the spherical component in 0.25D steps first and then 0.05D steps. The final sphere was when equality was first achieved between the red and green letters in the test.

The second study was conducted at the School of Optometry and Vision Science in the University of New South Wales in Australia. Participants in this study had 4 visits, with refraction performed at visit 1 and follow-ups occurring in the following 3 visits. Each participant was given eyeglasses made with 0.25D steps and 0.05D steps. The first pair of glasses was dispensed at visit 2 and evaluated at visit 3, whereas the second pair was dispensed at visit 3 and evaluated at visit 4. Each participant had identical frames for their lenses.

All participants used the Quality-of-Vision questionnaire for visits 1, 3, and 4 to evaluate the quality of their vision prior to the new lenses and with each pair of new glasses.

There were 66 participants included in the first study, with a mean (SD) age of 24.1 (2.3) years and 43 of whom were women. The second study included 51 participants with a mean age of 26.8 (5.9) years, 17 of whom were women.

No differences in refractions were found in either study. However, significantly better results were found with glasses with 0.05D steps for all acuity-based measurements with no significant effect for visit or interaction between lens type and visit. Habitual spectacles (lenses used prior to study) were found to have worse frequency of symptoms compared with the study lenses whereas no difference was found between study lens type.

Although there no differences in vision-quality between the lens types at dispensing, vision quality was found to be better after 7 days of wear when wearing 0.05D-step lenses. However, this difference was negligible. Participants were found to prefer the 0.05D-step lenses at visit 4 after 7 days of wear at a higher proportion.

Patients who preferred the 0.05-step lenses were less myopic (mean [SD], –2.6 [–1.1]D vs –3.6 [1.5]D). When dividing the participants from study 2 into untreated, treated, and mixed groups based on the difference between refractions, low contrast visual acuity (LCVA) with 0.25D steps was significantly better in the untreated group compared with the treated group. Both the untreated and treated groups had better LCVA using the 0.05D-step lenses and no difference was found in those who had mixed treatment. Better vanishing optotype acuity was found in patients with 0.05D steps and no difference was found in the mixed group. Contrast sensitivity was better for the treated group when using 0.05D steps but no difference was found in the untreated and mixed groups.

Results for the duochrome equality could have been biased due to unmasked investigators performing both refractions. Refractions for 0.25D steps were performed first, which could have increased proportion of eyes that achieved equality in 0.05D steps. Binocular balancing was not performed. Refractive errors had a restricted range due to including only healthy young adults.

The researchers concluded that duochrome equality and better average high contrast visual acuity (HCVA) was found in a higher proportion of participant eyes with refraction in 0.05D steps. Lenses with 0.05D steps had better average HCVA, LCVA, vanishing optoptype acuity, and contrast sensitivity.

Reference

Jia T, Tilia D, Papas E, et al. Comparison of vision performance of spectacles prescribed to 0.05D versus 0.25D steps. Clin Exp Optom. Published online April 20, 2023. doi:10.1080/08164622.2023.2202305