Asymmetric Thickness Intracorneal Ring Segments for Keratoconus

Area of Science:

• Ophthalmology
• Corneal Surgery
• Vision Science

Background:

• Keratoconus is a progressive corneal ectasia leading to irregular astigmatism and vision impairment.
• Asymmetric/irregular astigmatism presents unique challenges in keratoconus management.
• Current treatments aim to stabilize the cornea and improve visual acuity.

Purpose of the Study:

• To evaluate the anatomical and functional outcomes of asymmetric thickness intracorneal ring segments (AS-ICRS) implantation.
• To assess the efficacy of AS-ICRS in eyes with keratoconus and specific asymmetric/irregular astigmatism phenotypes (type 2 and type 3).

Main Methods:

• Retrospective observational study of 19 patients (21 eyes) with keratoconus undergoing AS-ICRS implantation.
• Analysis of demographic data, uncorrected (UDVA) and corrected (CDVA) distance visual acuity.
• Pentacam measurements including topographic astigmatism, keratometry (K1, K2, Kmax), and aberrometry (total RMS, HOA, Zernike coefficients).

Main Results:

• Significant improvements in UDVA and CDVA were observed post-implantation (p<0.017 and p<0.001, respectively).
• Substantial reduction in topographic astigmatism (1.97±1.5D, p<0.001) and steepest meridian (K2) (2.76±1.9D, p<0.001).
• Aberrometry showed a trend towards reduced total RMS and HOA, with a significant decrease in the comatic aberration component (p<0.001).

Conclusions:

• AS-ICRS implantation effectively improved clinical, topographic, and aberrometric parameters in keratoconus patients with asymmetric astigmatism.
• The procedure demonstrated clinical efficacy and a favorable safety profile.
• A tendency towards greater improvement was noted in type 2 keratoconus phenotypes.