Endothelial cell damage after riboflavin-ultraviolet-A treatment in the rabbit.
OBJECTIVE
To evaluate the possible cytotoxic effect of combined riboflavin-ultraviolet-A (UVA) treatment on the corneal endothelium.


METHODS
Department of Ophthalmology, Technical University of Dresden, Dresden, Germany.


METHODS
The right eyes of 34 New Zealand White rabbits were treated with riboflavin and various endothelial UVA doses ranging from 0.16 to 0.9 J/cm2 (0.09 to 0.5 mW/cm2, 370 nm) and postoperative enucleation times of 4 hours and 24 hours. The endothelial cells were evaluated in histological sections. The terminal deoxynulceotidyl transferase deoxy-UTP-nick-end labeling (TUNEL) technique and transmission electron microscopy were used to detect apoptosis.


RESULTS
There was no endothelial damage in the 6 rabbit eyes enucleated at 4 hours. In those enucleated at 24 hours, there was significant necrosis and apoptosis of endothelial cells in the corneas treated with an endothelial dose of > or =0.65 J/cm2 (0.36 mW/cm2), which is about twice the endothelial UVA dose used in the treatment of keratoconus patients.


CONCLUSIONS
In rabbit corneas with a corneal thickness less than 400 microm, the endothelial UVA dose reached a cytotoxic level of > or =0.65 J/cm2 (0.36 mW/cm2) using the standard surface UVA dose of 5.4 J/cm2 (3 mW/cm2). Pachymetry should be routinely performed before riboflavin-UVA treatment; in thinner corneas, irradiation should not be done because of the cytotoxic risk to the endothelium.
Wollensak
Gregor
G
Department of Ophthalmology, Technical University of Dresden, Dresden, Germany. gwollens@hotmail.com
Spoerl
Eberhard
E
Wilsch
Michaela
M
Seiler
Theo
T
D000818:Animals; D017209:Apoptosis; D004548:Elasticity; D004728:Endothelium, Corneal / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology / Q000528:radiation effects*; D005260:Female; D020287:In Situ Nick-End Labeling; D008854:Microscopy, Electron; D009336:Necrosis; D017319:Photosensitizing Agents / Q000009:adverse effects*; D011817:Rabbits; D012256:Riboflavin / Q000009:adverse effects*; D013997:Time Factors; D014466:Ultraviolet Rays / Q000009:adverse effects*
D017319:Photosensitizing Agents; D012256:Riboflavin