Large Filtering Blebs Research Articles

Filtering bleb-induced giant papillary conjunctivitis

Pathogenesis of giant papillary conjunctivitis is still elusive and many hypotheses are being proposed to explain the irritative symptoms associated with it. The research data available to date shows that mechanical, immunological and allergic components are involved in this to various extents. We report a rare cause of giant papillary conjunctivitis which was induced by a large filtering bleb following trabeculectomy surgery for glaucoma. A 30-year-old female, operated for glaucoma filtering surgery in her right eye 15 years back, presented with ocular irritation. Clinical evaluation revealed two giant papillae on the superior tarsal conjunctiva which coincided with the large filtering bleb with its peripheral extension. The fellow eye was normal and no association with any allergic disorders was noted. The patient responded symptomatically to the topical application of anti-inflammatory and anti-allergic medications. The giant papillae decreased considerably in size but the diffuse papillary response persisted. Though multiple etiological factors have been proposed for the giant papillary conjunctivitis, only a single case report is available where a filtering bleb is the causative factor. The mechanical irritation caused by the large-sized bleb seems to be the provoking agent in our case taking into consideration the position of the papillae that coincides with the peripheral extension of the bleb.

Effect of cryotherapy on large filtering bleb with thin wall after trabeculectomy

目的 探讨滤过泡冷冻术治疗巨大薄壁滤过泡的安全性和疗效.方法 采用滤过泡冷冻术治疗小梁切除术后滤过功能过强的巨大薄壁滤过泡14例16只眼.手术均在表面麻醉下进行,术后随访3～36个月,平均(24.4±11.1)个月.结果 16只眼均顺利完成手术.术前眼压1～5 mmHg,平均(3.25±1.13)mm Hg;术后眼压5～14 mm Hg,平均(8.81±2.95)mm Hg,手术前后眼压变化差异具有统计学意义(t=9.52,P=0.000).手术前有7只眼存在黄斑水肿,手术后消失.术后有6只眼视力上升2行以上,手术前后视力差异具有统计学意义(Z=-2.226,P=0.026).术后滤过泡无渗漏,无滤过泡感染等并发症.结论 滤过泡冷冻术治疗巨大薄壁滤过泡具有手术时间短、简单易行、并发症少,疗效确切的优点。

Treatment of Overhanging Blebs With Frequency-Doubled Nd:YAG Laser

Large overhanging blebs can be associated with various complications (eg, overfiltration, endophthalmitis, and dellen formation). Argon laser treatment of such blebs has already been described. The authors used frequency-doubled Nd:YAG laser in 3 eyes of 3 patients with large filtering blebs. Gentian violet was used to stain the bleb surface and enhance the laser absorption. Laser spots were applied over the bleb surface. Bleb shrinkage and remodeling was observed in all 3 eyes. Intraocular pressure remained normal, suggesting that the filtering capability of the blebs was maintained.

Surgical Management of the Symptomatic Overhanging Filtering Bleb

Large filtering blebs that evolve after trabeculectomies can be bothersome to the patient, especially when overhanging the cornea. Partial bleb excision is warranted to relieve the patient from discomfort or even visual impairment. Surgical partial excision of the overhanging corneal part of the bleb was performed in four patients who had undergone earlier trabeculectomy without application of antimetabolites. Duration of follow-up after excision ranged from 9 months to 4 years. Successful reduction of the excessive bleb and continued satisfactory control of intraocular pressure (IOP) were achieved in all four cases. Partial excision of the corneal part of the bleb did not lead to bleb leakage in any of the cases. Surgical blunt dissection of the overhanging the morphologic features of the bleb and ensuring continued control of IOP and relief of symptoms. Alternative methods, such as autologous blood injection, cryoapplication, application of trichloracetic acid, or application of Nd:YAG laser, are noninvasive but do not allow precise rearrangement of bleb architecture.

Dellen Associated With Filtering Blebs

Dellen may occur in the corneas of eyes with filtering blebs. Nine cases of such dellen were encountered in a series of 97 consecutive trabeculectomies. In two such patients, the dell progressed to a deep corneal ulcer, although in most cases it healed uneventfully with minor changes in therapy. The use of topical prednisolone acetate during the postoperative period may also contribute to dellen formation by inhibiting corneal epithelial wound healing. However, the most important factor predisposing to dellen formation was poor tear-film integrity adjacent to the bleb. The secretion of the aqueous tears seemed to have little or no effect on dellen formation. Almost all dellen occurred in eyes with large filtering blebs.

Reconstruction of conjunctiva on the limbus following the excision of an excessively large filtering bleb (author's transl)

After total excision of an excessively large filtering bleb extending to the cornea, the conjunctiva was dissected from the upper half of the eyeball and fixed by sutures into a step of the corneal periphery obtained by a keratectomy of 1 mm large strip of superficial cornea tissue along the upper half of the limbus. In 10 eyes operated on in this way -- and in seven of them over four years -- the newly developed filtrating bleb is flat and shows a well vascularised wall without any signs of degeneration.