Abstract
PurposeTo 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.MethodsIn 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.ResultsThe 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.ConclusionThe 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.
Highlights
Keratoconus is a progressive disease with architectural alterations in the cornea, such as thinning and irregular bulging forward, which results of changes in the cornea’s biomechanical properties [1, 2]
Key Messages: Patients with corneal ectasia suffer from a poor uncorrected visual acuity and improvement can be challenging especially in patients with contact lens intolerance
Visual rehabilitation by contact lenses or spectacles is challenging in both types of keratectasia since they are associated with a variety of refractive errors due to the irregular topography [7]
Summary
Keratoconus is a progressive disease with architectural alterations in the cornea, such as thinning and irregular bulging forward, which results of changes in the cornea’s biomechanical properties [1, 2]. The predominant optical error is astigmatism with less higher-order aberrations than keratoconus. Visual rehabilitation by contact lenses or spectacles is challenging in both types of keratectasia since they are associated with a variety of refractive errors due to the irregular topography [7]. Prior to the introduction of corneal crosslinking (CXL) by Seiler et al in 1996, the only available treatment in the course of these progressive diseases was a penetrating keratoplasty with higher risks of loss of visual acuity or severe complications [8]. Since the progression of keratectasias can be stopped in most cases, the demand of a reasonable refractive treatment for the increasing population of patients with stable keratectasia is substantial, in particular, if contact lens intolerance is present. An alternative approach is the use of phakic IOLs as a refractive treatment for stable keratectasia came up, these lenses were originally only designed for the treatment of regular astigmatism [11]
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