Toric phakic IOLs in keratoconus—evaluation of preoperative parameters on the outcome of phakic anterior chamber lens implantation in patients with keratoconus

Abstract

Purpose To evaluate the influence of the type of the keratectasia and preoperative keratometry readings on the efficacy of implantation of iris-fixated phakic anterior chamber intraocular lenses (pIOL) in patients with keratoconus. Methods In this retrospective study, iris-fixated pIOLs (Artisan/Artiflex (Ophtec®), Verisyse/Veriflex (AMO®)) were implanted in 38 eyes of 22 patients with stable keratoconus. Thirty-six eyes underwent corneal crosslinking (CXL) prior to the lens implantation. The refractive outcome was evaluated 6 weeks postoperatively and the influence of preoperative refraction and topo- and tomographical factors were analyzed. Results The mean postoperative uncorrected distance visual acuity (UDVApost) was 0.25 ± 0.15 logMAR and was not statistically different from the mean preoperative corrected distance visual acuity (CDVApre), which was 0.24 ± 0.13 logMAR. Twenty-seven eyes (71%) reached UDVApost/CDVApre ≥ 1 (efficacy index), whereas patients with PMD-like ectasia (n = 14) showed significantly (p = 0.003) higher efficacy index (100%) than patients diagnosed with keratoconus (n = 24) (54%). Higher eccentricity of the maximum posterior elevation showed a significant beneficial influence on the efficacy index (p = 0.021). Furthermore, a higher Amsler-Krumeich stage and preoperative MAE were correlated with a worse UDVApost. The mean absolute spherical equivalent was significantly decreased from 5.71 ± 4.96 D to 1.25 ± 1.20 D (p < 0.001). No significant difference was found in endothelial cell count. Conclusion The results indicate that the implantation of phakic iris-fixated anterior chamber IOLs is a reasonable refractive option for patients with keratoconus. Keratoconus patients with a pellucidal marginal degeneration (PMD)-like appearance ectasia seem to benefit most from such procedures.

Indications for keratoplasty in management of corneal ectasia

“…Toric IOLs are most commonly used, as they can correct for high levels of astigmatism when combined with other procedures [9 ▪▪ ,27]. Successful anterior and posterior phakic IOL implantation has been reported in contact-lens intolerant patients with low degrees of irregular astigmatism [28,29 ▪ ].…”

Differences in anterior chamber depth in keratoconus patients with binocular very asymmetry ectasia

“…Currently, widely used calculation formulas, such as the Kane formula, BUII, Olsen (four-factor), Haigis, Holladay 2 and Barrett True-K, involve measurements of axial length, keratometry, anterior chamber depth (ACD), lens thickness and central corneal thickness (CCT) [ 10 – 12 ]. Thus, anterior chamber parameters are important factors for the evaluation of intraocular lens (IOL) implantation surgery [ 13 – 15 ], and it is clinically important to effectively evaluate changes in the anterior chamber after the development of keratoconus.…”