Purposes: To describe the clinical characteristics of functioning blebs in Japanese glaucoma patients after primary trabeculectomy with adjunctive mitomycin-C (MMC) and to correlate their associations with postoperative bleb leakage.
Design: A prospective, observational case series.
Participants: One hundred sixty-two glaucoma patients who had undergone primary trabeculectomy with MMC at the University of Tokyo Hospital at least 3 months before were examined between December 1997 and February 1998.
Methods: A predesigned data form was completed at each visit. Ophthalmologic examinations included Goldmann applanation tonometry, slit-lamp examination, and Seidel tests with and without digital ocular pressure (DOP).
Main outcome measures: Properties of the functioning bleb, including bleb appearance, thickness of bleb wall, dimensions of bleb and avascular area, and leakage status with and without DOP.
Results: Of 162 Japanese patients, 162 eyes with functioning blebs were included. There were no differences in bleb characteristics among the different types of primary glaucoma. With a long postoperative duration, blebs tended to be thinner (P = 0.024). With DOP, the leaking rate increased from 3.1% to 5.6%, and the oozing rate increased from 11.1% to 35.8% (P < 0.001). Logistic regression analysis indicated that the larger the avascular area, the more likely the bleb leaked without DOP (P = 0.016). When DOP was applied, leakage was more likely to occur in the blebs with a long postoperative duration (P = 0.002) or with a large avascular area (P < 0.001).
Conclusions: The clinical characteristics of filtering blebs were similar in Japanese patients with different types of primary glaucoma. Blebs with a large avascular area were associated with a higher risk of bleb leakage. Attention to the increased chance of leakage induced by DOP is important, especially for blebs with a long postoperative duration. Ophthalmologists should be aware of late bleb-related complications in addition to bleb function.