The effect of different thickness scleral lens on corneal parameters in eyes with keratoconus

Abstract

Purpose: To investigate the impact of different-thickness scleral lenses (SLs) on corneal thickness, curvature, and fluid reservoir thickness in keratoconic eyes. Methods: Schiempflug imaging and AS-OCT was captured before and immediately following 6 h of SL wear. Different-thickness lenses were used while keeping the other parameters the same. The timing of the measurement for day 1 and day 2 was matched to allow for the control of the confounding influence of diurnal variation. Results: Immediately after 6 h of lens wear, no statistically significant difference ( P > 0.05) was noted in corneal edema in any region and quadrants between thin- and thick-lens wearers. The calculated percentage of corneal edema was also within the range of overnight closed eye physiological swelling. Pentacam measured higher central corneal thickness compared to AS-OCT in both baselines and after 6 h of lens wear. The current investigation reported minimal but not statistically significant ( P > 0.05) flattening in anterior and steepening in posterior curvature parameters in both thin and thick SLs. The mean reduction in the fluid reservoir thickness was 80.00 ± 3.99 and 79.36 ± 3.84 microns after 6 h of thin- and thick-lens wear, respectively, which was not statistically significant ( P > 0.05). A statistically significant positive correlation (r = 0.67, P = 0.02) was found between lens thickness and change in anterior steep k with thick-lens wear. Conclusion: Central lens thickness of 200–400 mm did not cause any significant change in corneal curvature and fluid reservoir thickness and did not induce clinically significant corneal edema after short-term SL wear.

Mini-Scleral Lens: An Effective Mode of Visual Rehabilitation in Eyes With Resolved Hydrops

“…There was no evidence of significant corneal edema in our patients up to a 3-month follow-up similar to previous studies in patients with keratoconus fitted with a scleral lens. Iqbal et al 23 showed that a scleral lens with a central lens thickness of 200 to 400 μm did not induce corneal edema after 6 hr of contact lens wear in patients with keratoconus. Cagliari et al 24 followed up with 22 patients with keratoconus who were fitted with scleral lenses for 90 days.…”

Central and peripheral scleral lens‐induced corneal oedema

“…Scleral lens‐induced corneal oedema is of clinical concern due to the potential hypoxic sequelae that may arise following long‐term lens wear in both healthy and diseased eyes, such as peripheral neovascularisation and graft failure or rejection (following keratoplasty). The magnitude of central corneal oedema varies with scleral lens fitting parameters such as the fluid reservoir thickness, 1 lens thickness, 2–5 lens oxygen permeability 6,7 and the lens wear conditions (e.g., duration, 8 eyelid closure 9–11 ). While it is understood that mechanical interaction between the back surface of a scleral lens and the peripheral cornea should be avoided, 12,13 few studies have investigated corneal oedema following scleral lens wear beyond the mid‐periphery.…”

Quality of life and vision assessment with scleral lenses in keratoconus

“…The fluid reservoir between the posterior lens surface and anterior cornea can neutralize irregular astigmatism of the anterior surface. [ 10 ] Conventional scleral lenses mask higher-order aberrations between 60% and 65%[ 11 12 ] through (1) approximate refractive index matching of the postlens tear layer and the cornea and (2) by providing a new, well-formed optical first refracting surface for light entering the eye. [ 13 ]…”