title: Plasminogen activator activity in tears after excimer laser photorefractive keratectomy.
abstract: OBJECTIVE
  To quantify changes of plasminogen activator activity in tear fluid during corneal re-epithelialization after excimer laser photorefractive keratectomy (PRK).
  
  
  METHODS
  Tear samples were collected with glass capillaries from 77 eyes of 42 patients immediately before and immediately after PRK treatment and on postoperative days 3 and 5. In 20 patients, the contralateral eye was similarly sampled to serve as control. Plasminogen activator activity in the tear samples was measured by a spectrophotometric method using human plasminogen and chromogenic peptide substrate, D-valyl-L-leucyl-L-lysine-p-nitroanilide (S-2251).
  
  
  RESULTS
  In tears of all eyes that underwent PRK, the plasminogen activator activities were lower immediately after PRK than were the preoperative values. For patient eyes with normal wound healing, tear plasminogen activator activities were significantly elevated above the preoperative level on the third postoperative day and then returned to the preoperative level by the fifth postoperative day. In contrast, tear plasminogen activator activities remained low through the third postoperative day in all (six) eyes in which haze developed after 3 to 6 months. The contralateral control eyes showed no appreciable change in plasminogen activator activity over the 5-day period.
  
  
  CONCLUSIONS
  Plasminogen activator activity levels measured in tears of excimer laser PRK-treated eyes may serve as a predictor of wound healing. Extended low levels of plasminogen activator activity through the third postoperative day correlate with the development of corneal healing abnormalities (haze). The low plasminogen activator activity could be not only an accompanying sign but also a cause of defective corneal wound healing.
authors.affiliation: Departments of Ophthalmology, University Medical School of Debrecen, Hungary.
authors.forename: A
authors.initials: A
authors.lastname: Csutak
authors.forename: J
authors.initials: J
authors.lastname: Tözsér
authors.forename: L
authors.initials: L
authors.lastname: Békési
authors.forename: Z
authors.initials: Z
authors.lastname: Hassan
authors.forename: A
authors.initials: A
authors.lastname: Berta
authors.forename: D M
authors.initials: DM
authors.lastname: Silver
mesh_terms: D000293:Adolescent; D000328:Adult; D019573:Epithelium, Corneal / Q000201:enzymology; D005136:Eye Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000201:enzymology / Q000601:surgery*; D018903:Photorefractive Keratectomy; D010960:Plasminogen Activators / Q000378:metabolism*; D013666:Tears / Q000201:enzymology*; D014945:Wound Healing
chemical_list: D005136:Eye Proteins; C042434:tear proteins; D010960:Plasminogen Activators