Scleral lens wearers tend to prefer quadrant-specific designs for increased comfort. Photo: Vision Research institute at Michigan College of Optometry. Click image to enlarge.
Upon comparing scleral lenses with a quadrant-specific (study lens) or a spherical (habitual lens) landing zone, researchers recently found that both provide good vision and do not affect IOP or corneal thickness. However, tear exchange was greater with spherical lenses, and patient comfort was improved with quadrant-specific lenses.
Seven participants (eight eyes) wore each lens for two weeks. Visual acuity, contrast sensitivity, IOP, fluid reservoir clearance, corneal thickness, tear exchange and lens experience were then measured. Variables were compared between lenses and before and after two hours of wear.
Visual acuity was not significantly different between the study lens and the habitual lens (0.12logMAR and 0.18logMAR, respectively). Contrast sensitivity was 1.3% with the study lens and 1.6% with the habitual lens. IOP did not change after two hours of wear with either lens, and corneal thickness did not change during wear with either lens. The fluorescein concentration with the study lens did not change after two hours but decreased to 46% of initial concentration under the habitual lens. Lens comfort was slightly better with the study lens (5.0 vs. 4.0, respectively).
Despite a lack of significant differences between objective parameters of the lenses, the team reported that patients preferred the quadrant-specific design. “Unintentional bias (from visual identification of characteristics of their new lenses) may have contributed to this preference. However, it is also possible that the current objective assessment of measurable parameters cannot adequately discriminate between very slight differences in lens performance that patients might notice and report,” they concluded in their paper for Eye & Contact Lens. “Including patient assessments of scleral lens wearing experience in future studies may provide practitioners with valuable insights into factors that contribute to optimal patient experience and an understanding of scleral lens fitting parameters that provide the most favorable patient-reported outcomes.”
Nau CB, Schornack MM, McLaren JW, et al. Tear exchange, intraocular pressure, and wear characteristics of quadrant-specific versus spherical haptic scleral lenses. Eye Contact Lens. August 16, 2022. [Epub ahead of print].