Intracorneal Ring Segments With 300° Of Arc In The Correction Of Central Keratoconus With High Asphericity.

To assess the visual results obtained with the implantation of a 300° arc intracorneal ring segment in cases of central keratoconus with high asphericity.

Fernández-Vega Universitary Institute (Oviedo), Spain.

Forty-two eyes with moderate to advanced central hyperprolate keratoconus (Amsler-Krumeich Grade III) were evaluated before and after implanting an inferior 300° ICRS (AJL Ophthalmic). The clinical measurements taken included manifest refraction, uncorrected (UDVA) and corrected (CDVA) distance visual acuity (logMAR scale), and corneal tomographic analysis (Sirius; Costruzioni Strumenti Oftalmici). Changes in the anterior and posterior corneal surfaces and the root mean square (RMS) for coma-like aberrations for a pupil size of 4.5 mm were evaluated. All examinations were performed before surgery and 6 months after surgery.

The mean UDVA improved from 1.12 ± 0.48 logMAR preoperatively to 0.73 ± 0.37 logMAR postoperatively (P < .0001). The mean CDVA changed from 0.33 ± 0.20 to 0.20 ± 0.11 logMAR (P < .0001). Postoperatively, the CDVA improved by two or more lines in 45.2% of the eyes and increased by one line in 19.04%, and none of the patients lost lines of CDVA. All of the anterior and posterior corneal tomographic parameters analyzed were significantly improved after surgery, except posterior flat keratometry, which remained unchanged. In 80.95% of the eyes, the postoperative mean keratometry was 50.00 diopters or less. The 6-month RMS for coma-like aberrations also declined significantly from 1.57 ± 0.68 to 1.06 ± 0.42 µm after surgery (P < .0001).

The results of this study show that the implantation of a 300° arc intracorneal ring segment is an effective and safe procedure for the correction of central keratoconus with high asphericity.