Intrastromal Corneal Ring Segments for Astigmatism Correction after Deep Anterior Lamellar Keratoplasty

Abstract

Background. To evaluate the change in corneal astigmatism after intrastromal corneal ring segment (ICRS) implantation in keratoconus patients with previous deep anterior lamellar keratoplasty (DALK). Design was a longitudinal, retrospective, interventional study. The study included 25 eyes of 24 patients with keratoconus who had DALK performed at least two years prior to ICRS implantation. All patients had a clear corneal graft with up to 8.00 D of corneal astigmatism and intolerance to contact lenses. The studied parameters were age, sex, corrected distance visual acuity (CDVA), maximum keratometry (K1), minimum keratometry (K2), spherical equivalent, and astigmatism. There was a statistically significant decrease in the postintervention analysis as follows: 3.5 D reduction in K1 (p < 0.001); 1.53 D in K2 (p = 0.005); and 2.52 D (p < 0.001) in the average K. The spherical equivalent reduced from −3.67 D (±2.74) to −0.71 D (±2.35) (p < 0.001). The topographic astigmatism reduced from 3.87 D preoperatively to 1.90 D postoperatively (p < 0.001). The CDVA improved from 0.33 (±0.10) to 0.20 (±0.09, p < 0.001). ICRS implantation is a useful option for the correction of astigmatism after DALK as it yields significant visual, topographic, and refractive results.

Intrastromal corneal ring segments followed by PRK for postkeratoplasty high astigmatism: prospective study

“…The 49% correction rate of the combination compares favorably with all studies of PRK (range of correction rate: 21% to 37%) and most studies of ICRS. 14,16,18,19,21–35 To our knowledge, only 2 studies of ICRS showed similar results (50% and 51%) but reported preoperative astigmatism below 4.0 D, whereas we reported a mean preoperative value of 7.88 ± 2.13 D. 17,20…”

“…[16][17][18][19][20][21] In addition, the ICRS studies reporting the lowest preoperative Kmax readings were the ones to report greater flattening. 16,17,19,20 Accordingly, we found a negative correlation between the preoperative Kmax and the improvement in both CDVA and ASTac. In our series, the safety protocol was a limiting factor in planning the ICRS thickness, which is directly related to corneal flattening.…”

Factors associated with short-term visual improvement after intracorneal ring segments implantation

“…When these methods fail, surgery is indicated to improve the corneal surface. When the cornea is transparent, implantation of polymethylmethacrylate (PMMA) intrastromal ring segments can be a successful option 6 .…”

Factores asociados a mejoría visual a corto plazo tras implantación de segmentos intraestromales en pacientes con queratocono

“…Cuando estos métodos fallan, está indicada la cirugía para mejorar la superficie corneal. Cuando la córnea se mantiene transparente, la implantación de segmentos de anillos intrastromales de polimetilmetacrilato (PMMA) puede ser una opción exitosa 6 .…”