title: Refractive and corneal aberrometric changes after intracorneal ring implantation in corneas with pellucid marginal degeneration.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  Retrospective, consecutive case series.
  
  
  METHODS
  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.
  
  
  METHODS
  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 > or =2 lines of BSCVA. Sphere (P = 0.02), cylinder (P<0.01), and spherical equivalent (P<0.01) were reduced significantly after surgery (P< or =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.
  
  
  BACKGROUND
  The authors have no proprietary or commercial interest in any materials discussed in this manuscript.
authors: Vissum/Instituto Oftalmológico de Alicante, Spain.
authors: David P
authors: DP
authors: Piñero
authors: Jorge L
authors: JL
authors: Alio
authors: Hector
authors: H
authors: Morbelli
authors: Antonio
authors: A
authors: Uceda-Montanes
authors: Bassam
authors: B
authors: El Kady
authors: Efekan
authors: E
authors: Coskunseven
authors: Inmaculada
authors: I
authors: Pascual
mesh_terms: D000328:Adult; D000368:Aged; D003315:Cornea / Q000503:physiopathology* / Q000601:surgery; D003316:Corneal Diseases / Q000503:physiopathology / Q000601:surgery*; D003319:Corneal Stroma / Q000601:surgery; D019781:Corneal Topography; D020878:Device Removal; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D012029:Refraction, Ocular / Q000502:physiology*; D012189:Retrospective Studies; D019738:Surgically-Created Structures; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult