title: Change in corneal microstructure with rigid gas permeable contact lens use following collagen cross-linking: an in vivo confocal microscopy study.
abstract: OBJECTIVE
  To study corneal microstructural changes with use of rigid gas permeable contact lenses (CLs) in keratoconus patients following collagen cross-linking (CXL).
  
  
  METHODS
  In a prospective, non-randomised, comparative case series, keratoconus patients with documented progression were offered CXL (365 nm, 3 mW/cm(2), 30 min with 0.1% riboflavin). Patients who refused CXL were fitted with CL and followed up for 6 months (keratoconus (KL)-CL; 25 eyes). Patients who underwent CXL were either fitted with CL 3 months after the procedure (CXL-CL; 26 eyes) or followed up with only spectacle correction (CXL-SL; 21 eyes). Outcome measures of over-refraction and corneal microstructure (confocal microscopy) were evaluated at time of CXL and 1, 2, 3, 4, 6 and 9 months after CXL.
  
  
  RESULTS
  There was a myopic shift in over-refraction by 0.37 D in CXL-CL (p=0.00), and 16/26 eyes required prescription of spectacles over CL to provide optimum vision; change in over-refraction was not seen in KC-CL. Patients using CL (CXL-CL and KC-CL) showed evidence of epithelial cell stress with increase in the superficial epithelial cell size and decrease in basal epithelial cell density. They also had a decrease in corneal sub-basal nerve plexus (CSNP) density and branching. Patients using spectacles after CXL showed regeneration of the sub-basal nerve plexus. Stromal keratocyte regeneration was unaffected with CL use.
  
  
  CONCLUSIONS
  CL use after CXL is associated with a delay in the regeneration of the CSNP and epithelial cell stress.
authors.affiliation: Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, , New Delhi, India.
authors.forename: Sri V
authors.initials: SV
authors.lastname: Sehra
authors.forename: Jeewan S
authors.initials: JS
authors.lastname: Titiyal
authors.forename: Namrata
authors.initials: N
authors.lastname: Sharma
authors.forename: Radhika
authors.initials: R
authors.lastname: Tandon
authors.forename: Rajesh
authors.initials: R
authors.lastname: Sinha
mesh_terms: D000293:Adolescent; D000328:Adult; D003094:Collagen / Q000378:metabolism*; D003261:Contact Lenses; D003315:Cornea / Q000294:innervation / Q000473:pathology*; D003319:Corneal Stroma / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D005139:Eyeglasses; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D007640:Keratoconus / Q000188:drug therapy / Q000628:therapy*; D008297:Male; D018613:Microscopy, Confocal; D009416:Nerve Regeneration / Q000502:physiology; D009882:Ophthalmic Nerve / Q000502:physiology; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011446:Prospective Studies; D017755:Prosthesis Fitting; D012256:Riboflavin / Q000627:therapeutic use; D055815:Young Adult
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin
keywords: Contact lens; Cornea