Intraoperative corneal thickness measurements during corneal collagen cross-linking with hypoosmolar riboflavin solution in thin corneas.
OBJECTIVE
To monitor corneal thickness during the corneal collagen cross-linking procedure in corneal ectatic diseases, by using isoosmolar riboflavin solution with 20% dextran and hypoosmolar riboflavin solution without dextran.


METHODS
The corneal thickness measurements were obtained at 5 different time points: after epithelial removal, after isotonic riboflavin solution application for 30 minutes, after hypotonic riboflavin solution application for 10 minutes, and after 10 and 30 minutes of isotonic riboflavin solution application.


RESULTS
A total of 9 eyes of 9 patients with progressive keratoconus (n = 8) and pellucid marginal degeneration (n = 1) were included in this study. After epithelial debridement, the thinnest pachymetric readings were between 331 and 399 μm (average, 376.11 ± 19.88 μm). The thinnest pachymetric measurements decreased significantly after the application of isoosmolar riboflavin solution for 30 minutes (by 55.22 ± 13.40 μm) and increased significantly after hypoosmolar riboflavin application for 10 minutes (by 59.56 ± 29.71 μm) (P < 0.01 for both). This artificial swelling effect was transient, and the thinnest pachymetric readings decreased significantly after 10 and 30 minutes of isoosmolar riboflavin application compared with thickness at the end of hypoosmolar riboflavin application (by 50.22 ± 29.68 μm and 65.11 ± 27.94 μm, respectively) (P < 0.01 for both).


CONCLUSIONS
The iatrogenic swelling effect of the hypoosmolar riboflavin solution might be short acting and not durable throughout the UVA application in collagen cross-linking procedure.
Eye Clinic, Beyoglu Eye Training and Research Hospital, Istanbul, Turkey.
Vedat
V
Kaya
Canan Asli
CA
Utine
Ömer Faruk
ÖF
Yılmaz
D000328:Adult; D001837:Body Weights and Measures; D003094:Collagen / Q000378:metabolism*; D003315:Cornea / Q000473:pathology*; D003319:Corneal Stroma / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D003911:Dextrans / Q000627:therapeutic use; D004108:Dilatation, Pathologic / Q000188:drug therapy; D006801:Humans; D007038:Hypotonic Solutions / Q000627:therapeutic use*; D007552:Isotonic Solutions / Q000627:therapeutic use; D007640:Keratoconus / Q000188:drug therapy* / Q000378:metabolism; D016343:Monitoring, Intraoperative; D009994:Osmolar Concentration; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D012256:Riboflavin / Q000627:therapeutic use*; D014466:Ultraviolet Rays
D003432:Cross-Linking Reagents; D003911:Dextrans; D007038:Hypotonic Solutions; D007552:Isotonic Solutions; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin