Local effects of previous conjunctival incisional surgery and the subsequent outcome of filtration surgery

PURPOSE: Previous ocular surgery involving conjunctival incision is a risk factor for failure of filtration surgery. To determine whether using adjunctive antimetabolite therapy may have a rational basis, a study was performed to determine whether the conjunctival cellular profile was altered by such surgery. METHODS: After a mean follow-up of 5.9 years, filtration surgery outcomes for 35 patients who had undergone conjunctival incisional surgery were retrospectively compared with 29 control and 18 matched patients who had not undergone such surgery. At the time of filtration surgery, a conjunctival biopsy specimen was obtained from all 82 patients, and these were quantitatively analyzed by light microscopy in a prospective manner. RESULTS: Trabeculectomy success for the con trol group (93%) was significantly higher than for the previous surgery group (38%) (P < .001). Compared with control tissue, conjunctiva from the patients who had undergone previous surgery contained more fibroblasts (P < .001, P < .05), macrophages (P < .01, P < .001), and lymphocytes (P = .001, P < .01) in both superficial and deep substantia propria (respective P values). Furthermore, trabeculectomy failure was associated with an increase in number of conjunctival fibroblasts in intraoperative specimens. CONCLUSIONS: Previous ocular surgery involving the conjunctiva increases the number of conjunctival fibroblasts and inflammatory cells. This may account for the increased risk of trabeculectomy failure. Perhaps on this basis, the use of adjunctive medication may be justified in patients who have undergone previous ocular surgery involving conjunctival incision. (C) 1998 by Elsevier Science Inc. All rights reserved.).