Plasminogen activator inhibitor in human tears after laser refractive surgery

Purpose

To observe levels of plasminogen activator inhibitor (PAI) in human tears after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK).

Setting

University medical center eye clinic.

Methods

Tear samples were collected from 46 eyes having PRK and 13 eyes having LASIK immediately before and after surgery and on the first (LASIK), third (PRK), and fifth (PRK) postoperative days. Analyses used enzyme-linked immunoassay, yielding 61 PRK PAI-1 determinations and 146 PRK and 35 LASIK PAI-2 determinations.

Results

All determinations of PRK PAI-1 were below the detection limit of 1 ng/mL of the original tear sample. In the PRK eyes, the mean PAI-2 concentration was 19.8 ng/mL ± 23.4 (SD) in preoperative tears, 112.7 ± 60.5 ng/mL immediately postoperatively, 12.1 ± 19.5 ng/mL after 3 days, and 15.5 ± 20.4 ng/mL after 5 days. In the LASIK eyes, the mean PAI-2 concentration was 19.0 ± 33.1 ng/mL preoperatively, 111.5 ± 69.2 ng/mL immediately postoperatively, and 15.7 ± 18.8 ng/mL after 1 day.

Conclusions

The similarity in the general time pattern of PAI-2 after PRK and LASIK suggests commonality in the enzymatic control response to corneal surgical wounding. Taken in the context of previous work, the observed levels of PAI-2 concentration in eyes with and without opacification suggest that in the postsurgical period, PAI-2 is not the controlling mechanism for the later development of corneal opacification and haze.