The role of lumican and keratocan genes in persistent subepithelial corneal haze following excimer laser photorefractive keratectomy.
OBJECTIVE
A retrospective clinical and a genetic study was carried out of severe subepithelial corneal haze occurring after photorefractive keratectomy (PRK). Since this clinical condition resembles the lumican-null mouse phenotype, mutation analysis of lumican and keratocan was carried out to investigate whether germline genetic alterations have an effect on development of severe corneal haze in humans. Corneal thickness, photoablation depth, and severity of persistent corneal haze were also analyzed. In vivo confocal microscopy examination was also performed to study corneal structure and endothelial cells.


METHODS
Severity of corneal haze was evaluated by slit-lamp biomicroscopy according to Hanna's scale. Corneal structure and endothelial cell shapes and density were viewed with a scanning confocal microscope. PCR-based mutational analysis was performed using temperature gradient gel electrophoresis (TGGE) and direct sequencing.


RESULTS
Preoperative corneal thickness was normal (539+/-23.13 microm, mean+/-SD), and the photoablation depth was 88.94+/-18.64 microm (mean+/-SD). The most severe corneal haze was grade 2.0 on Hanna's scale one year after PRK. In vivo confocal microscopy also showed normal endothelial cell density and morphology. Aside from an intronic polymorphism in a control, no genetic alterations were found in the lumican and keratocan genes.


CONCLUSIONS
There was no evidence that endothelial dysfunction and germline mutation of lumican and keratocan genes participate in the etiology of subepithelial corneal haze. Our findings suggest that the mechanisms of the development of severe corneal opacity are different in humans after PRK compared to the lumican deficient knockout mouse model.
Szabó
Viktória
V
Department of Ophthalmology, Semmelweis University, Faculty of Medicine, Budapest, Hungary. szabo_viktoria@hotmail.com
Balogh
Katalin
K
Süveges
Ildikó
I
Rácz
Károly
K
Hunyady
László
L
Nagy
Zoltán Zsolt
ZZ
D000328:Adult; D016022:Case-Control Studies; D002452:Cell Count; D011508:Chondroitin Sulfate Proteoglycans / Q000235:genetics*; D003315:Cornea / Q000473:pathology; D003318:Corneal Opacity / Q000235:genetics* / Q000473:pathology; D004728:Endothelium, Corneal / Q000473:pathology; D005260:Female; D006801:Humans; D007632:Keratan Sulfate / Q000235:genetics*; D054018:Lasers, Excimer; D000071234:Lumican; D008297:Male; D018613:Microscopy, Confocal; D018903:Photorefractive Keratectomy / Q000009:adverse effects*; D011509:Proteoglycans / Q000235:genetics*; D012189:Retrospective Studies; D012720:Severity of Illness Index
D011508:Chondroitin Sulfate Proteoglycans; C490948:KERA protein, human; C000604306:LUM protein, human; C000604307:Lum protein, mouse; D000071234:Lumican; D011509:Proteoglycans; D007632:Keratan Sulfate