A novel large diameter rigid gas-permeable corneal contact lens design for keratoconus

Abstract

Purpose: To assess the fitting process and clinical feasibility of a novel large diameter rigid gas-permeable (RGP) corneal contact lens (CL) presenting regular or reverse geometry for managing keratoconus (KC). The lens was designed to rest on the peripheral cornea and vault over the cone, aiming to enhance visual quality, comfort, and corneal physiology.

Methods: 32 KC patients across all severity stages, including central, paracentral and peripheral cones enrolled. Lens parameters were customized from corneal measurements obtained via Oculus Pentacam HR tomography, mainly based on sagittal height and accounting for adequate tear film clearance. Visual acuity (VA), contrast sensitivity (CS), ocular complications, and user satisfaction were evaluated at baseline, and at one week and three months of lens wear.

Results: Twenty-four patients (41 eyes) were fitted and completed the 3-month follow-up (median age of 28.5 years, 9 females). A median of 2 trial lenses per eye (interquartile range of 4.5) were needed during the fitting process. Significant improvements in median VA (baseline: 0.32 logMAR; three months: 0.01 logMAR; p = 0.002) and CS (p < 0.001 at all frequencies) were observed compared to baseline values. Ocular complications remained below clinical significance, with superior limbic keratoconjunctivitis showing significant reduction over time (p < 0.001). Patient satisfaction was high, with a median daily lens wear of 9.5 h. Most users (79.2%) reported consistent comfort with their CLs.

Conclusion: The novel large diameter RGP corneal CL demonstrated comparable efficacy to existing RGP CL designs, offering high levels of comfort and improved vision with minimal ocular complications.

Keywords: Contact lens; Keratoconus; Large contact lens diameter; Rigid gas-permeable corneal contact lens; Sagittal height.

Fig. 1

Sodium fluorescein image of a large diameter rigid gas-permeable corneal CL for keratoconus. The white rings correspond to the different zone changes (D₀, D₁, D₂ and D₃), and the yellow ring shows the total lens diameter (D_T).

Fig. 2

Monocular contrast sensitivity values at baseline (BAS) and three-months (3_M) at spatial frequencies of 3, 6, 12 and 18 cycles per degree (cpd). The shaded area represents normal contrast sensitivity values at each spatial frequency. (*) denote atypical values, and correspond to the same patient.

Fig. 3

Severity of the ocular complications observed at baseline and at the 3-months follow-up, as determined with the Efron Grading Scales. A reference red line is shown to denote the threshold for clinical significance for ocular complications (grade 3). Statistically significant differences in severity between baseline and three months are denoted by *.