Clinical evaluation of the effectiveness of asymmetric intrastromal corneal ring segments with progressive base width for management of keratoconus.

PURPOSE

To evaluate visual, refractive, corneal topographic, and aberrometric results of asymmetric intracorneal ring segments (AS ICRSs) with variable width to manage asymmetric keratoconus.

SETTING

Quinze-Vingts National Ophthalmology Hospital, Paris, France.

DESIGN

Prospective observational study.

METHODS

According to their tomographic pattern, patients receiving 1 AS ICRS (INTRASEG asymmetric) were included. AS INTRASEG features an arc length of 150 degrees and asymmetric width (800 to 1200 μm). Anterior segment optical coherence tomography combined with Placido disc MS-39 was performed preoperatively and 1 month and 6 months postoperatively to assess keratometric and aberrometric outcomes and epithelial remodeling. Refractive outcomes were also evaluated. Analysis of the correction profile according to the width of the base of the ICRS was performed.

RESULTS

43 keratoconic eyes were analyzed. Significant improvement of corrected distance visual acuity was observed (logMAR): from 0.34 ± 0.23 to 0.08 ± 0.10 ( P < .001). The flattening effect was higher at the widest end than the narrowest end (-10.59 ± 2.59 diopters [D] vs -4.54 ± 1.30 D, P < .001), contributing to reduce the Symmetry Index Front from 9.06 ± 4.02 to 2.21 ± 3.81. Total higher-order aberrations (HOAs) reduced from 2.13 ± 0.94 μm to 1.77 ± 0.59 μm ( P < .001) with halving of the coma aberration from 1.84 ± 0.87 μm to 0.89 ± 0.50 μm ( P < .001).

CONCLUSIONS

Implantation of AS INTRASEG in asymmetric keratoconus improves refractive, topographic, and aberrometric parameters. The progressive width of the base is efficient for reducing vertical asymmetry and HOAs of asymmetric keratoconus phenotype.