Influence of Specialty Contact Lens Wear on Posterior Corneal Tomography in Keratoconus Subjects

Abstract

Objective: 

To evaluate the effect of specialty contact lens (CL) wear on posterior corneal tomography in keratoconus subjects.

Methods: 

Patients with keratoconus who were wearing specialty CL were included in this retrospective cohort study. Tomographic parameters were evaluated with Scheimpflug imaging (Pentacam HR) before lens fitting and immediately after removal of CLs worn habitually for a period of several months. Subjects were divided into groups, according to type of lens (corneal, scleral, and hybrid) and keratoconus severity based on Belin/Ambrosio D (BAD-D) score, for further analysis.

Results: 

Thirty-four eyes of 34 subjects diagnosed with keratoconus were included. Mean duration of habitual CL wear was 7.0±0.3 months. For the entire cohort, a small increase in flat keratometric reading at the anterior corneal surface (K1F; P=0.032) and at the posterior surface (K1B; P=0.041) was found. In the corneal CL group (10 eyes; 29.4%), flattening of the anterior corneal curvature was detected (K_max; P=0.015). An increase in K1B value was seen in the scleral CL group (15 eyes; 44.1%) (P=0.03). Combined topometric indices showed a small but significant difference in the entire cohort (P<0.05) and in the subgroups of corneal CL wear and of moderate keratoconus (BAD-D score≥7).

Conclusion: 

Various types of specialty CLs exert a differential influence on corneal parameters. A small steepening of keratometry at the posterior surface (K1B) was observed in the scleral lens group. Although corneal lens wear flattens the anterior cornea (K_max), it does not significantly alter the posterior corneal surface.