It is well established that modern scleral lenses (SLs), manufactured from highly oxygen-permeable materials, induce mild corneal edema of approximately 2% in young healthy eyes.^1,2 However, in eyes that have reduced endothelial cell density, SL wear may result in epithelial and stromal edema.³ These changes may compromise corneal integrity, visual acuity, and contrast sensitivity. Notably, measurable reductions in visual acuity occur when corneal thickness increases by approximately 4% to 6%.⁴

Therefore, it is important to understand how SL wear influences changes in corneal thickness and corneal radius of curvature and how these structural changes relate to visual performance. One study reported longitudinal variations in anterior corneal curvature, corneal pachymetry, and posterior corneal curvature. It also evaluated their impact on visual outcomes after 12 months of SL wear in eyes that had keratoconus (KC) without intrastromal corneal ring segments (KC group) and in eyes that had keratoconus with intrastromal corneal ring segments (ICRS) (KC-ICRS group).⁵ All 65 participants diagnosed with KC were divided into those 2 groups.

All participants wore SLs for 8 hours each day for 1 year. The SLs used in this study had an irregular corneal design, a diameter of 16.5 mm, and were manufactured from paflufocon material with a Dk of 100 and a water content of less than 1%. The central thickness was 0.30 mm for a −3.00 D lens. Lens powers ranged from +1.00 D to −16.00 D, with sagittal heights between 3,900 and 5,600 microns. Measurements included corneal thickness, anterior and posterior corneal curvature, and high-contrast visual acuity, evaluated before and after SL wear. In the KC-ICRS group, corneal thickness significantly increased.

Curvature analysis revealed inferior steepening and superior flattening in the KC group, whereas the KC-ICRS group demonstrated anterior corneal flattening in the central and superior-nasal regions. Posterior corneal curvature changes included central flattening with peripheral steepening. High-contrast visual acuity remained stable across all visits and in both groups.

No significant changes in corneal thickness were observed in the KC group across visits, although mild central thinning was noted, with a 1.30% reduction after 12 months of SL wear. In the KC-ICRS group, central pachymetry decreased slightly by 0.15% at 12 months, while a statistically significant 3.98% increase in thickness was observed in the superior quadrant. These findings contrast with a previous short-term study of 8 hours of SL wear, which reported superior corneal thinning, suggesting that wear duration and corneal response to ICRS may influence regional pachymetric changes.⁶

SLs affected anterior corneal curvature differently in eyes with KC with and without ICRS. In the KC group, central corneal flattening was observed across the corneal diameter, accompanied by relative steepening in the superior and inferior regions. In contrast, the KC-ICRS group demonstrated more generalized anterior corneal flattening across all corneal diameters. When translated into changes in anterior corneal power, these flattening effects correspond to clinically meaningful shifts of up to approximately 1.00 D (equivalent to about 0.20 mm) after SL removal.

Long-term SL wear resulted in measurable corneal morphological changes, including increased superior corneal thickness and region-specific curvature alterations, which differed based on the presence of ICRS. These changes did not adversely affect visual acuity, supporting SLs as a safe and effective long-term vision correction option for KC.

These findings emphasize the importance of individualized fitting and ongoing monitoring. The authors encourage practitioners to perform corneal topography before and after SL wear to counsel patients regarding potential transient visual changes following lens removal and to improve patient satisfaction and monitor corneal biomechanics.

References

1. Esen F, Toker E. Influence of Apical clearance on mini-scleral lens settling, clinical performance, and corneal thickness changes. Eye Contact Lens. 2017;43:230-235. doi: 10.1097/ICL.0000000000000266

2. Vincent SJ, Alonso-Caneiro D, Collins MJ. The time course and nature of corneal oedema during sealed miniscleral contact lens wear. Cont Lens Anterior Eye. 2019;42:49-54. doi: 10.1016/j.clae.2018.03.001

3. Guillon NC, Godfrey A, Hammond DS. Corneal oedema in a unilateral corneal graft patient induced by high Dk mini-scleral contact lens. Cont Lens Anterior Eye. 2018;41:458-462.

4. Hess RF, Garner LF. The effect of corneal edema on visual function. Invest Ophthalmol Vis Sci. 1977;16:5-13. doi: 10.1016/j.clae.2018.05.004

5. Serramito M, Privado-Aroco A, Carracedo G. One-year impact of scleral lens wear on corneal morphology in keratoconus with and without intracorneal ring segment. Healthcare (Basel). 2026;14(1):131. doi: 10.3390/healthcare14010131

6. Serramito-Blanco, M.; Carpena-Torres, C.; Carballo, J.; Piñero, D.; Lipson, M.; Carracedo, G. Anterior corneal curvature and aberration changes after scleral lens wear in keratoconus patients with and without ring segments. Eye Contact Lens. 2019;45:141-148. doi: 10.1097/ICL.0000000000000534

Melissa Barnett, OD, FAAO, FSLS, practices at Baker Optometry. She also is an International Coaching Federation (ICF) associate certified coach. She has received remuneration from ABB, AbbVie, Alcon, Azura, Bausch + Lomb, BCLA, Bruder, Cloudbreak Pharma, Dompé, Epion, OCuSOFT, ScienceBased Health, STAPLE Program, Tarsus, and Théa Pharma.

This content supported by Contamac.