Posterior Corneal Surface Changes Are Not Evident Following Orthokeratology

The posterior corneal surface does not undergo significant changes following 1 year of orthokeratology (ortho-k) treatment despite changes observed in the anterior corneal surface, anterior chamber depth, lens thickness, and axial length, according to research published in Heliyon. 

Researchers retrospectively reviewed charts from 37 children with myopia (girls, 14; mean age, 10.70 years; mean spherical equivalent [SE], -3.26 diopters [D]) treated with ortho-k lenses during a 12-month period. Study participants underwent corneal topography measurements, including flat and steep keratometry of the anterior and posterior corneal principal meridians, central corneal thickness, posterior thinnest elevation of the cornea, posterior central elevation of the cornea, and posterior mean elevation of the cornea, and ocular biometry measurements, which included anterior chamber depth, lens thickness, and axial length. 

The research team compared anterior and posterior corneal surface changes following 1 year of treatment. 

Anterior corneal surface changes were noted at 1-year follow-up and included both flat and steep keratometry decreases (both P < .000). Anterior chamber depth decreased significantly (mean difference, -0.06 mm; P =.001), while lens thickness and axial length increased significantly (mean difference, 0.05 and 0.23, respectively; P =0.00 for both). The flat and steep keratometry of the posterior corneal surface, however, did not undergo significant alterations following treatment compared with baseline (P =.426 and P =.134, respectively). 

Posterior corneal surface elevation was not significantly affected by ortho-k treatment, and no significant changes in posterior central elevation, thinnest elevation, or mean elevation were noted at the 12-month follow-up visit (P =.051; P =.952; and P =.197 respectively). 

“[T]his study showed that posterior cornea curvature during ortho-k treatment kept stable through 12 months observation,” according to the researchers.

This finding is clinically significant because it shows that ortho-k treatment does not interfere with early signs for subclinical keratoconus.

Study limitations include a short follow-up duration, small sample size, and ethnic homogeneity, which may have limited the globalization of these findings.