One-year follow-up of corneal confocal microscopy after corneal cross-linking in patients with post laser in situ keratosmileusis ectasia and keratoconus.
OBJECTIVE
To investigate corneal tissue alterations after corneal collagen cross-linking in patients with post laser in situ keratosmileusis (LASIK) keratectasia and keratoconus.


METHODS
Prospective comparative case series.


METHODS
Five patients (5 eyes) with iatrogenic keratectasia after LASIK and 5 patients (5 eyes) with progressive keratoconus were included. All eyes underwent corneal cross-linking and were assessed by corneal in vivo confocal microscopy. Three normal/healthy and 3 post-LASIK without ectasia corneas were also examined as controls.


RESULTS
All corneas revealed normal epithelial thickness before and after surgery. Images of both keratoconic and post-LASIK corneal ectasia eyes revealed similar morphologic alterations. The subepithelial nerve plexus was absent immediately after treatment; regeneration of nerves was evident after the third postoperative month. Keratocytes were absent from the anterior 300 mum of the stroma in the first 3 months while the posterior stromal density of keratocytes was increased. Corneal collagen fibers in the anterior stroma were distributed unevenly in a net-like formation. Full-thickness keratocyte repopulation in the anterior and mid-corneal stroma was detected 6 months after treatment. The corneal endothelium did not undergo any significant changes, since the cell density and hexagonality was not found altered during the follow-up period.


CONCLUSIONS
Keratocyte nuclei apoptosis in the anterior and intermediate corneal stroma along with collagen alterations were observed during the first 3 postcorneal cross-linking months. Gradual keratocyte repopulation was demonstrated over the following months. Corneal alterations after corneal cross-linking were similar in both keratoconic and post-LASIK corneal ectasia eyes.
Kymionis
George D
GD
Institute of Vision and Optics, University of Crete, Crete, Greece. kymionis@med.uoc.gr
Diakonis
Vasilios F
VF
Kalyvianaki
Maria
M
Portaliou
Dimitra
D
Siganos
Charalampos
C
Kozobolis
Vasilios P
VP
Pallikaris
Aristophanis I
AI
D003094:Collagen / Q000378:metabolism*; D003319:Corneal Stroma / Q000378:metabolism / Q000473:pathology*; D004108:Dilatation, Pathologic / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology / Q000378:metabolism; D005500:Follow-Up Studies; D006801:Humans; D007049:Iatrogenic Disease; D007640:Keratoconus / Q000175:diagnosis* / Q000188:drug therapy / Q000209:etiology / Q000378:metabolism; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects*; D018613:Microscopy, Confocal; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011183:Postoperative Complications; D011446:Prospective Studies; D012256:Riboflavin / Q000627:therapeutic use; D014466:Ultraviolet Rays
D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin