title: Optical coherence tomography and confocal microscopy following three different protocols of corneal collagen-crosslinking in keratoconus.
abstract: OBJECTIVE
  We compared the efficacy and early morphological changes in the cornea following conventional (C-CXL), transepithelial by iontophoresis (I-CXL), and accelerated (A-CXL) collagen cross-linking in keratoconus.
  
  
  METHODS
  A total of 45 eyes of 45 patients with progressive keratoconus who underwent corneal collagen crosslinking (CXL) was divided into three groups: C-CXL (n = 15), A-CXL (n = 15), and I-CXL (n = 15). Patients were examined before surgery and at 1-, 3-, and 6-month intervals following surgery. Density of corneal sub-basal nerves, anterior and posterior keratocytes, corneal endothelium, demarcation line depth, and maximal simulated keratometry values (Kmax) were all assessed.
  
  
  RESULTS
  Compared to preoperative values, the mean corneal sub-basal nerve and anterior stromal keratocyte densities were significantly lower at 6 months in the C-CXL and A-CXL groups (P < 0.001), whereas they returned to preoperative values in the I-CXL group (P = 0.083 and P = 0.909, respectively). The corneal demarcation line was visible 1 month after surgery in 93% of cases (mean depth, 302.8 ± 74.6 μm) in the C-CXL group, 87.5% (mean depth, 184. 2 ± 38.9 μm) in the A-CXL group, and 47.7% (mean depth, 212 ± 36.5 μm) in the I-CXL group (P = 0.006). There were no significant differences between confocal microscopy and optical coherence tomography measurements of the corneal demarcation line depth (P > 0.05). The Kmax, corneal central thickness, and BSCVA remained stable during the whole study period.
  
  
  CONCLUSIONS
  Iontophoresis was associated with weaker damage of corneal sub-basal nerves and anterior keratocytes compared to conventional procedures, but the demarcation line was present in less than 50% of cases and was more superficial than with the traditional procedure.
authors.affiliation: Quinze-Vingts National Ophthalmology Hospital, Sorbonne Universités, UPMC Univ Paris 06, Paris, France.
authors.forename: Nacim
authors.initials: N
authors.lastname: Bouheraoua
authors.affiliation: Quinze-Vingts National Ophthalmology Hospital, Sorbonne Universités, UPMC Univ Paris 06, Paris, France.
authors.forename: Lea
authors.initials: L
authors.lastname: Jouve
authors.affiliation: Quinze-Vingts National Ophthalmology Hospital, Sorbonne Universités, UPMC Univ Paris 06, Paris, France.
authors.forename: Mohamed
authors.initials: M
authors.lastname: El Sanharawi
authors.affiliation: Quinze-Vingts National Ophthalmology Hospital, Sorbonne Universités, UPMC Univ Paris 06, Paris, France.
authors.forename: Otman
authors.initials: O
authors.lastname: Sandali
authors.affiliation: Quinze-Vingts National Ophthalmology Hospital, Sorbonne Universités, UPMC Univ Paris 06, Paris, France.
authors.forename: Cyrille
authors.initials: C
authors.lastname: Temstet
authors.affiliation: Quinze-Vingts National Ophthalmology Hospital, Sorbonne Universités, UPMC Univ Paris 06, Paris, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Loriaut
authors.affiliation: Quinze-Vingts National Ophthalmology Hospital, Sorbonne Universités, UPMC Univ Paris 06, Paris, France.
authors.forename: Elena
authors.initials: E
authors.lastname: Basli
authors.affiliation: Quinze-Vingts National Ophthalmology Hospital, Sorbonne Universités, UPMC Univ Paris 06, Paris, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Borderie
authors.affiliation: Quinze-Vingts National Ophthalmology Hospital, Sorbonne Universités, UPMC Univ Paris 06, Paris, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Laroche
mesh_terms: D003094:Collagen / Q000378:metabolism*; D003432:Cross-Linking Reagents; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007478:Iontophoresis / Q000379:methods*; D007640:Keratoconus / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D008297:Male; D018613:Microscopy, Confocal / Q000379:methods*; D008875:Middle Aged; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011446:Prospective Studies; D041623:Tomography, Optical Coherence / Q000379:methods*; D016896:Treatment Outcome
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen
keywords: confocal microscopy; cross-linking; keratoconus; optical coherence tomography