Histological, immunohistochemical, and ultrastructural findings in human corneas after photorefractive keratectomy.
BACKGROUND
Four human corneas that had undergone photorefractive keratectomy (PRK) and subsequent penetrating keratoplasty were examined by means of light and electron microscopy in an attempt to detect possible causes for complications after PRK.


METHODS
Four eyes with a central corneal leukoma resulting from a previous PRK treatment underwent penetrating keratoplasty respectively 3 days, 3 months, 5 months, and 13 months after the refractive procedure. Different excimer laser instruments (Meditec MEL 50, Summit UV200, and VISX 20/20) had been used. The corneal buttons removed were submitted for light microscopy, electron microscopy and immunohistochemistry.


RESULTS
An immature (one to two layers, basement membrane anomalies) but continuous epithelium was present even in the 3-day specimen; between six and eight epithelial layers could be seen in the 13-month specimen, which still presented an undulated aspect of the otherwise normal basement membrane. A continuous acellular collagen layer underlying the epithelium of the ablated area was detected in the superficial stroma of all examined corneas. No Descemet's membrane or endothelial alterations could be seen.


CONCLUSIONS
Despite recovery of a continuous epithelial layer as early as 3 days after PRK, abnormalities of both epithelium and superficial stroma could be detected in all specimens, including the one obtained 13 months after the refractive procedure.
Balestrazzi
E
E
University Eye Clinic, L'Aquila, Italy.
De Molfetta
V
V
Spadea
L
L
Vinciguerra
P
P
Palmieri
G
G
Santeusanio
G
G
Spagnoli
L
L
D000328:Adult; D001485:Basement Membrane / Q000648:ultrastructure; D003315:Cornea / Q000737:chemistry / Q000601:surgery / Q000648:ultrastructure*; D003318:Corneal Opacity / Q000209:etiology / Q000473:pathology* / Q000601:surgery; D003319:Corneal Stroma / Q000648:ultrastructure; D003598:Cytoskeletal Proteins / Q000032:analysis; D004848:Epithelium / Q000737:chemistry / Q000601:surgery / Q000648:ultrastructure; D016326:Extracellular Matrix Proteins / Q000032:analysis; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D015948:Keratoplasty, Penetrating; D054018:Lasers, Excimer; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D018903:Photorefractive Keratectomy / Q000009:adverse effects*; D012030:Refractive Errors / Q000473:pathology*; D054140:Refractive Surgical Procedures
D003598:Cytoskeletal Proteins; D016326:Extracellular Matrix Proteins