Refractive and corneal aberrometric changes after intracorneal ring implantation in corneas with pellucid marginal degeneration

Abstract

Purpose: To evaluate refractive, visual, and aberrometric changes in corneas with pellucid marginal degeneration (PMD) implanted with intracorneal ring segments (ICRS) during a 6-month follow-up. Design: Retrospective, consecutive case series. Participants: We included 21 consecutive eyes of 15 patients ranging in age from 21 to 73 years old and with a diagnosis of PMD. This diagnosis was made on the basis of slit-lamp (inferior corneal thinning), corneal topography (“butterfly” pattern), and refractive findings (significant against-the-rule astigmatism with best spectacle-corrected visual acuity loss). Methods: A multicenter, retrospective analysis of patients undergoing ICRS implantation for the management of PMD in 4 ophthalmologic centers was performed. Surgery was indicated in all cases because of reduced best spectacle-corrected visual acuity (BSCVA) and/or contact lens intolerance or dissatisfaction. Mechanical corneal tunnelization was performed in 7 eyes and femtosecond laser-assisted tunnelization in 14 eyes. Intacs were implanted in only 3 eyes whereas KeraRings in 18 eyes. Refractive and corneal aberrometric changes were analyzed during a 6-month follow-up. Main Outcomes Measures: Uncorrected corrected visual acuity (UCVA) and BSCVA, refraction, keratometry, and root mean square (RMS) for different kinds of corneal aberrations. Results: The UCVA did not improve at 6 months after surgery (P = 0.11). The BSCVA increased from a mean preoperative value of 0.54 to a mean postoperative value of 0.75 (P = 0.06). At 6 months, 44.44% of eyes gained ≥2 lines of BSCVA. Sphere (P = 0.02), cylinder (P<0.01), and spherical equivalent (P<0.01) were reduced significantly after surgery (P≤0.02). Mean keratometry decreased significantly from 44.95 diopters (D) preoperatively to 43.19 D at 6 months postoperatively (P<0.01). The RMS values for astigmatism, higher order residual, and coma-like aberrations were significantly reduced with surgery (P = 0.03). In addition, significant negative correlations of preoperative RMS astigmatism (r = −0.90) and primary spherical aberration (r = −0.86) with postoperative BSCVA were also found. Segment ring explantation was performed in a total of 4 eyes owing to poor visual outcome. Conclusions: Implantation of an ICRS is an effective option for the treatment of 2nd-order and higher aberrations in corneas with PMD. Preoperative corneal astigmatism and spherical aberration seem to be limiting factors for a good visual outcome.