Posters

Intracorneal ring segment implantation for keratoconus: topographic and clinical effects of 1 vs 2 ring segments

Poster Details

First Author: A.Youssef FRANCE

Co Author(s):    A. Mazen   e. Sylvain   Z. Karen   J. Elias           

Abstract Details

Purpose:

To assess the effect of number of ring segments on corneal remodeling and clinical outcome after sequential intracorneal ring segment (ICRS) implantation and crosslinking (CXL) for keratoconus. Empirical information about the corneal response to ICRS is important to predict outcome and to guide clinicians in the treatment of keratoconus.

Setting:

Beirut Eye Specialist Hospital, Beirut, Lebanon

Methods:

This is a retrospective interventional case series including 95 eyes of 66 patients (mean age 24�Â�±7.5years). All eyes received ICRS (Keraring or Intacs) implantation followed one month later by CXL. ICRS number, type and ring thickness was dependent on preoperative refractive error, steepness and shape of corneal cone. Data was analyzed preoperatively and 1-year postoperatively for refractive and topographic values (uncorrected distance visual acuity (UDVA); corrected distance visual acuity (CDVA); sphere; cylinder; spherical equivalent (SE); Kmax; Kflat; Ksteep; index of surface variance (ISV); index of vertical asymmetry (IVA); index of height decentration (IHD) and the other 4 topographic indices).

Results:

63.2% of eyes received one ring (group-1) and 36.8% received two rings (group-2). Preoperatively, group-2 had significantly higher K-readings, higher refractive errors and worse CDVA. Postoperatively, keratoconus indices for group-1 improved significantly higher then for group-2 [ISV: 23% vs. 6% (p<0.001); IVA: 23% vs. 6% (p<0.001); IHD: 45% vs. 20% (p=0.001), respectively]. In contrast, group-2 had more pronounced improvement of refractive errors [Sphere: 4.0D vs. 2.2D (p=0.02); SE: 3.5D vs. 1.8D (p=0.02), respectively]. Concerning functional parameters, CDVA group-2 improved more with borderline significance [8.1 (14%) vs. 4.3 (6%) ETDRS letters (p=0.07)].

Conclusions:

The number of ring segments implanted has a large influence on postoperative corneal remodeling. Implantation of one ring has a stronger regulating effect on corneal shape then the implantation of two rings as demonstrated by topographic indices. Implantation of two rings, however, has a more pronounced effect on the improvement of refractive errors and CDVA then 1 ring.

Financial Disclosure:

NONE