Br J Ophthalmol 1999;83:1360-1363
( December )
Soluble Fas and Fas ligand in human tear fluid after
photorefractive keratectomy
Ilpo Tuominena, Minna Vesaluomaa, Anna-Maija Teppob, Carola Grönhagen-Riskab, Timo Tervoa
a Helsinki University
Eye Hospital, Helsinki, Finland, b Department of Medicine, Helsinki
University Hospital, Helsinki, Finland
Correspondence to: Ilpo Tuominen, Helsinki University Eye Hospital, Eye Bank, PO Box 220, FIN-00029 HUCH, Finland
Accepted for publication 2 July 1999
BACKGROUND/AIMS
The
Fas-Fas ligand system is thought to be involved in stromal cell
apoptosis after corneal wounding. The aim was to measure changes in
human tear fluid levels of soluble Fas (sFas) and Fas ligand (sFasL)
following myopic photorefractive keratectomy (PRK).
METHODS
Tear samples
of 59 patients were collected preoperatively, and 1 or 2 days after
PRK. Tear fluid sFas or sFasL concentrations were determined using
sandwich ELISAs. Subsequently, tear flow corrected concentrations
(releases) were calculated to compensate for the postoperative tear hypersecretion.
RESULTS
The
preoperative tear fluid flows (TFF) were 6.4 (1.7) µl/min (mean
(SEM)) in sFas group (n = 18), and 7.5 (1.5) µl/min in sFasL group (n = 39). Postoperatively TFFs increased to 37.9 (10.9) µl/min (p = 0.003) and 58.3 (7.0) µl/min (p = 0.000), respectively. The mean
preoperative sFas concentration (24.4 (11.6) U/ml) decreased to 9.7 (4.1) U/ml (p = 0.001) postoperatively, and the mean sFasL concentration (299.1 (28.8) ng/l) to 118.7 (15.9) ng/l (p = 0.000). However, the release of both substances increased significantly: sFas
from 87.3 (29.4) mU/min to 229.4 (82.9) mU/min (p = 0.002) and sFasL
from 1620.6 (226.4) fg/min to 4777.1 (596.1) fg/min (p = 0.000).
CONCLUSIONS
Both sFas
and sFasL are normal constituents of human tears. Despite a decrease in
concentrations related to reflex tears, the release of sFas and sFasL
increases significantly after excimer laser photorefractive
keratectomy, which suggests that they are involved in corneal healing
after PRK in humans.
© 1999 by British Journal of Ophthalmology