Corneal Surface Elevation and Thickness in Relation to the Fit of Rigid Contact Lenses in Keratoconus and After Corneal Cross-Linking

Abstract

Alma Biscevic,1,2,* Melisa Ahmedbegovic-Pjano,1,* Senad Grisevic,1,* Nita Bejdic,1,* Fanka Gilevska,1,* Sudi Patel1,2,* 1Laser and Refractive Surgery, Eye Clinic Svjetlost, Sarajevo, Bosnia, Herzegovina; 2Laser and Refractive Surgery, Eye Clinic Svjetlost, Zagreb, Croatia*These authors contributed equally to this workCorrespondence: Sudi Patel, Eye Clinic Svjetlost Zagreb, Heinzelova 39, Zagreb, 10000, Croatia, Email [email protected]: To determine if factors pertaining to corneal thickness and elevation were linked to the prescribed back optic zone radius and overall diameter in keratoconus (group I), and cross-linked keratoconus (group II), cases successfully fitted with rigid contact lenses.Patients and Methods: A review of cases adapted to contact lens wear (Rose K™) and assessed using Pentacam™ (for corneal anterior surface topography, astigmatism, elevation, and topographic thickness variation) was undertaken to determine the significance of any correlation with comfort, lens usage, grading of keratoconus, corrected distance visual acuity (with glasses and contacts), refractive error, prescribed lens powers, back optic zone radius and overall diameter values were assessed.Results: Chief findings were, comfort was rated highly, lenses were worn for more than 10 hours/day in 75% of cases. RCL corrected distance logMAR acuities (median, mode, inter-quartile ranges) were 0.11, 0.12 (0.08– 0.13) and 0.08, 0.08 (0.06– 0.11) in groups I and II, respectively. Multiple linear regression revealed significant correlations (p< 0.01) between the [A] back optic zone radius, the thinnest value of corneal thickness (x1) and anterior corneal surface elevation (x2). The respective r2 values were 0.471 in group I and 0.512 in group II. [B] overall diameter, x1 and x2. The respective r2 values were 0.282 in group I and 0.505 in group II.Conclusion: RCLs were well-tolerated in both groups. The r2 values imply there is a 50% chance of correctly predicting the suitable back optic zone radius in both groups, a 50% chance of correctly predicting the overall diameter in group II and 28% in group I cases using just x1 and x2. The thinnest value of corneal thickness and anterior corneal surface elevation could be used to quickly select the BOZR and OD during RCL fitting. This has the potential to reduce chair-time, waste and improve efficiency.Keywords: thinnest corneal thickness, lens radius and diameter

Keywords

• thinnest corneal thickness
• lens radius and diameter