Size Matters: A Comparative Study on Midday Fogging and Lens Settling in Patients With Keratoconus Wearing Mini-Scleral Lenses With Two Different Diameters.

Purpose: The objective of this study was to compare the changes in postlens fluid optical density, timing and quantity of lens settling, and the clinical performance between two different mini-scleral lenses.

Methods: Seventeen eyes of 10 patients with keratoconus were fitted with a 15-mm mini-scleral lens (AirKone Scleral Lenses; Laboratoire LCS, Normandy, France), and 15 eyes of 10 patients with keratoconus were fitted with 16.5-mm mini-scleral lenses (Misa Lenses; Microlens Contactlens Technology, Arnhem, The Netherlands). The lens fit was evaluated with biomicroscopy and anterior segment optical coherence tomography (AS-OCT). At 0, 2, and 4 hrs, corneal clearances were measured with AS-OCT, and optical density measurements were made by Scheimpflug tomography. High-contrast visual acuity (HCVA) and contrast sensitivity (CS) were assessed at each time point. At the end of the 4th hour, participants' comfort, visual quality, and general satisfaction were evaluated with a 5-point Likert scale and 100-mm Visual Analog Scale (VAS) scale.

Results: The mean age (24.4 ± 5.4 vs. 21.7 ± 4.5, P = 0.145) and best spectacle-corrected HCVA (0.36 ± 0.15 vs. 0.35 ± 0.20, P = 0.984) were similar in both groups. The mean Snellen HCVA significantly improved with dispensing both mini-scleral lenses and remained stable at 4 hrs in both groups. In comparison, CS significantly decreased at 4 hrs in both groups ( P = 0.02). Both groups' optical density significantly increased over time ( P = 0.003). In the 15-mm mini-scleral lens group, the settling amount was 62.2 ± 11.9 μm (62.6%) and 99.5 ± 14.2 μm (100%) at 2 and 4 hrs, respectively; in the 16.5-mm mini-scleral lens group, it was 46.4 ± 22.3 μm (56.4%) and 82.1 ± 37.3 μm (100%) at 2 and 4 hrs, respectively. More than 50% of settling occurred in the first 2 hrs in both groups. No significant difference was observed between the two groups with regard to visual acuity, CS, optical density, and total settling amount at 4 hrs ( P > 0.05). Patient in the 15-mm mini-scleral lens group scored higher in comfort (4.65 ± 0.7 vs. 3.60 ± 0.9), visual quality (4.76 ± 0.4 vs. 3.73 ± 0.7), and overall satisfaction (95.7 ± 6.0 vs. 65.3 ± 20.3) ( P < 0.0001).

Conclusion: Patients reported a heightened level of contentment with the smaller-diameter lens; however, it is crucial to emphasize that both diameter scleral lenses showcase comparable clinical efficacy, midday fogging, and settling.