Prolonged impairment of peripheral corneal epithelium barrier function after successful trabeculectomy.

PURPOSE

To quantitate changes in the ocular surface after trabeculectomy using a newly designed fluorophotometer-based method.

METHODS

We studied 23 normal eyes (23 volunteers), six eyes (six patients) within 1 month after surgery (early group), and 14 eyes (14 patients) 3 months or longer after surgery (late group). Also, to elucidate time-dependent changes in corneal epithelium barrier function, we measured fluorescein uptake before and after trabeculectomy prospectively in the central and peripheral cornea of six glaucomatous eyes in six patients.

RESULTS

Mean fluorescein uptake (+/- SE) in the central cornea 30 minutes after instillation was 34.4 +/- 3.8 ng/ml, 113.5 +/- 65.8 ng/ml, and 43.1 +/- 12.8 ng/ml, respectively, in the normal, early, and late groups, which represents a statistically significant increase in the early group, but subsequent recovery to near normal range in the late group (P = .0225, normal vs early groups; P = .437, normal vs late groups, unpaired t test). Mean fluorescein uptake in the peripheral cornea was 34.5 +/- 6.1 ng/ml, 276.2 +/- 120.5 ng/ml, and 378.4 +/- 118.2 ng/ml, respectively, in the normal, early, and late groups, which represents a statistically significant increase in both the early and late groups (P = .0267, normal vs early groups; P = .0310, normal vs late groups, unpaired t test). In the early and late groups, significant differences were shown in fluorescein uptake between the central and peripheral cornea, but these differences were not evident in the normal group. The prospective study showed that fluorescein uptake in the peripheral cornea was 35.3 +/- 13.0 ng/ml and increased to 308.2 +/- 96.6 ng/ml at the third postoperative month (P = .022, paired t test) and to 277.9 +/- 145.5 ng/ml at the end of the first postoperative year (P = .154, paired t test).

CONCLUSION

Peripheral corneal epithelium barrier function adjacent to the filtration bleb following trabeculectomy may be significantly impaired for at least 1 year after surgery.