Children who wore daily disposable hydrogel soft contact lenses for more than 10 years may have shown no statistically significant differences in corneal epithelial thickness, stromal thickness, or most endothelial characteristics compared with nonwearers.
In the cross-sectional study, researchers evaluated 42 young adult participants who had worn daily disposable hydrogel soft contact lenses since childhood and age-matched controls with no history of contact lens wear. Those in the contact lens group began wearing lenses at a mean age of 10.6 years and had worn them for an average of 11 years, at least 10 hours daily, and 6 days weekly. Mean ages at assessment were 21.6 years among contact lens wearers and 21.3 years among controls. All contact lens wearers used daily disposable omafilconA hydrogel lenses.
The researchers measured corneal epithelial thickness (CET) and corneal stromal thickness (CST) using anterior segment optical coherence tomography across the central 2-mm region and mid-peripheral and peripheral regions extending to 6 mm. They also assessed endothelial cell density (ECD), variation in endothelial cell size (CV), and the proportion of hexagonal endothelial cells (HEX) using noncontact specular microscopy. Endothelial measurements covered the central cornea and 6 peripheral regions.
Central CET was nearly identical between groups, averaging 52.2 μm among contact lens wearers and 52.4 μm among controls. Central CST averaged 487.6 μm and 478.3 μm, respectively. Neither measure differed statistically significantly between groups, and no differences were identified across the measured mid-peripheral and peripheral regions. An additional analysis found no statistically significant difference in epithelial thickness distribution from the central to peripheral cornea.
Central ECD was also comparable, averaging 3,076 cells/mm² among contact lens wearers and 3,064 cells/mm² among controls. The HEX was 66% and 67%, respectively. Neither ECD nor hexagonality differed statistically significantly between groups across the assessed regions.
The researchers identified CV. Although central cell size variation was comparable between contact lens wearers and controls at 30% and 28%, respectively, contact lens wearers demonstrated statistically significantly greater variation in the superior and superonasal corneal regions. The between-group differences were 3.7 and 3.5 percentage points, respectively. No statistically significant differences were identified in the remaining peripheral regions.
The localized increase in endothelial cell size variation could be associated with reduced oxygen transmission or mechanical stress in regions covered by the upper eyelid. However, endothelial cell density and hexagonality remained comparable between groups in these regions. The researchers also reported no ocular adverse events among contact lens wearers during the preceding 10 years.
The researchers proposed that characteristics of the daily disposable hydrogel lenses, including their relatively low modulus and reduced accumulation of surface deposits, may help explain the absence of widespread corneal differences. These potential mechanisms were not directly evaluated.
The study had several limitations. Its cross-sectional design prevented longitudinal assessment of corneal changes throughout the wearing period. The small sample size may have limited detection of subtle differences, and corneal thickness measurements were restricted to the central 6 mm. Additionally, all contact lens wearers used the same hydrogel material and replacement schedule, limiting generalizability to other lens types and wearing regimens. The groups also differed in refractive error.
“This study provides further reassurance that daily disposable hydrogel [soft contact lenses] are a safe and suitable option for children over a typical myopia control treatment period,” wrote lead study author HiuYan Lam, of the School of Optometry at Aston University in the United Kingdom, and colleagues.
Full disclosures of the study authors can be found in the study.
