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Histopathological findings in filtering blebs with recurrent blebitis

We report clinical courses and histopathological findings of excised blebs from two patients with recurrent blebitis.

Case reports

Case 1

A 79 year old man with a past history of lung cancer and diabetes mellitus underwent trabeculectomy with 5-fluorouracil in his right eye for a diagnosis of primary open angle glaucoma (POAG) in 1989. In January 1994, bleb leakage from an avascular bleb was confirmed for the first time and prophylactic topical erythromycin had been applied. In September 1994, he experienced ocular pain and hyperaemia in his right eye and blebitis was diagnosed. Culture of aqueous humour was positive for enterococcus. He was treated with topical ofloxacin, micronomicin, and a subconjunctival injection of amikacin and the infection resolved. After then, bleb leak was not observed at any regular visit. In March 1998, blebitis occurred with a bleb leak in the same position. Although infection was controlled with almost same medication as before, the leak did not stop after any conservative therapies. In October 1998, the bleb was resected and the free conjunctival flap was transplanted. Histology of the excised bleb indicated a on e to two layered thin epithelium with goblet cell depletion and a poor inflammatory response (Fig 1).

Case 2

An 89 year old man underwent a Scheie procedure (thermal sclerostomy) in his left eye for a diagnosis of POAG in June 1980. Avascular bleb was observed but he was unable to visit the hospital for periodic examination because of his age. In August 1998, he presented with ocular pain and discharge in his left eye and blebitis was diagnosed. Culture from conjunctival scraping grew Staphylococcus aureus. The infection was successfully treated with anterior chamber irrigation with gentamicin (8 mg/1) and topical ofloxacin. The bleb leak persisted, however and topical ofloxacin was prophylactically applied thereafter. In January 2001, blebitis occurred in the same position. Topically applied SBPC, ofloxacin, and micronomicin abolished the infection.

Because the bleb leak persisted. the bleb was resected to prevent reinfection and anterior advancement of the conjunctiva was performed in February 2001. Histological examination of the bleb specimen revealed an attenuated epithelium with goblet cell depletion and hyaline change with a loss of inflammatory responses in the lamina propria.

Comment

According to previous reports, the epithelia of leaking blebs following adjunctive use of antimetabolites shows focal or general thinning. (1 2) In cases of leaking bleb after filtering surgery without the use of antimetabolites, Sinnreich et al (3) reported similar epithelial thinning, white Addicks et al (4) reported normal epithelium. Both of our cases were similar to the former. Moreover, there was goblet cell depletion in both of our cases. Mucin is a highly adhesive substance secreted from goblet cells and mostly forms as surface mucin over the cornea or conjunctiva. which has an important function as a physical, biological barrier on the ocular surface, such as elimination of foreign bodies or control of micro-organisms. (5) Thus, histological findings of these two cases of recurrent bleb infection are compatible with dysfunction against bacterial infection.

Inflammatory reaction in the stroma of the bleb is decreased with the use of mitomycin C, (1 2 6-8) while cases of leaking blebs without antimetabolites reportedly show moderate subconjunctival inflammation. (3) Case 2 in the present study, without the use of antimetabolites, had a low inflammatory reaction. Poor immune response may be related to the poor blood supply in these ischaemic blebs and compatible with the poor immune response to bacterial infection.

Waheed and his colleagues reported clinical characteristics of 12 eyes with recurrent bleb related infections and they concluded that eyes that have been successfully treated for bleb related infection remain at risk for recurrent infection. (9) Histopathological findings showing thinning and breakdown of epithelial structures in the present study may explain this findings.

H Matsuo, G Tomita, M Araie, Y Suzuki, Y Kaji

Department of Ophthalmology, The University of Tokyo School of Medicine, Tokyo, Japan

H Obata

Department of Ophthalmology, Jichi Medical School, Tochigi, Japan

S Tanaka

Department of Ophthalmology, Teikyo University School of Medicine Ichihara Hospital, Chiba, Japan

Correspondence to: Hiroshi Matsuo, MD, Department of Ophthalmology, The University of Tokyo School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan; …