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PubMedDate not supplied

Photoablative laser-grid trabeculectomy in glaucoma filtering surgery: histology and outflow facility measurements in porcine cadaver eyes.

BACKGROUND AND OBJECTIVE: Mid-infrared laser technology opens new perspectives in experimental glaucoma surgery. The aim of the study was to determine the efficacy of grid-laser trabeculectomy to reduce aqueous outflow resistance sufficiently in perfused porcine cadaver eyes. MATERIALS AND METHODS: Twenty-five freshly enucleated porcine cadaver eyes were randomly assigned to either laser-grid trabeculectomy (LGT), conventional trabeculectomy (CT), or control. In all surgical cases a scleral flap was prepared in a standardized manner. In order to penetrate into the anterior chamber a 1 x 2 mm sclerectomy was performed in CT, and 10 transscleral ablation craters were created in LGT. An erbium:YAG laser (2.96 microm) was used for transscleral photoablation. Radiation was delivered in a single 6 mJ-pulse of 200 micros duration by means of an articulated zirconium fluoride optical fiber and a 200 microm quartz fiber-tip. Outflow facility was measured at a constant perfusion pressure. RESULTS: Laser-grid trabeculectomy (LGT) yielded reproducible ablation areas varying between 210-300 microm in diameter, with 90% being full-thickness penetrations. Collateral thermal damage was less than 30 microm. Outflow facility measurements revealed a statistically significant increase (mean +/- SD) from 0.255 +/- 0.096 microL/min/mm Hg in control eyes (n = 9) to 0.772 +/- 0.157 microL/min/mm Hg in the LGT group (n = 9), and 2.957 +/- 0.602 microL/min/mm in the CT group (n = 7). Flattening of the anterior chamber, folding of Descemet's membrane, and iris prolapse were only observed in the CT eyes but not in the GLT group. CONCLUSION: Application of the laser-grid trabeculectomy produces patent transscleral perforation with minimal collateral tissue damage and effects a significant reduction (67%) in outflow resistance without any postoperative hypotony-related complications.

Animals↗
PubMed1984

Filtering surgery in childhood glaucoma.

A review of 38 eyes of 24 patients receiving filtration surgery for childhood glaucoma is presented. A total of 54 procedures were performed, including both thermal sclerostomies and trabeculectomies. Successful control of intraocular pressure was obtained in 20 eyes (52%). Average follow-up time was four years, two months. Filtration surgery is seen as a useful technique in the treatment of childhood glaucoma when goniotomy fails. It also is useful in those conditions where the success rate of goniotomy is expected to be low.

Adolescent↗
PubMed1993

[Mitomycin C in glaucoma surgery].

Glaucoma filtering surgery fails because of scarring of the filtering bleb. Fibroblasts proliferation from the episclera and Tenon capsule play an important role in the scarring process. The use of antimetabolites in glaucoma filtering surgery have a beneficial effect on the lowering of intraocular pressure especially in eye at poor surgery prognosis. They inhibit the fibroblasts proliferation and subsequent scarring of filtering bleb. 5 fluorouracil improves chance of success with filtering surgery but the necessity of multiple subconjunctival injections has many disadvantages including discomfort for the patient and ocular surface problems such as corneal defect and conjunctival wound leak. Mitomycin C with its focal applications limits the toxic effects to tissue directly exposed to the drug. A single intra-operative application leads to a more hypotensive effect with less corneal complications which are two major advantages of this treatment (Kitazawa and al.): Success rate at one year without medical treatment: 88% with MMC-40% with 5 FU. Different tissue culture studies as well as clinical studies demonstrate that the antiproliferative effect of MMC is 100 times more powerful than 5 fluorouracil. Mitomycin C might probably interfere with other steps in the wound healing process. Mitomycin C seems to be a better treatment than 5 fluorouracil. Nevertheless long term randomized prospective human studies are necessary to confirm it.

Adult↗
PubMed1996

The use of bioerodible polymers and daunorubicin in glaucoma filtration surgery.

PURPOSE: Glaucoma filtering surgery usually fails from postoperative fibroblast proliferation, collagen deposition, and subsequent sclerostomy or bleb scarring. Daunorubicin inhibits fibroblast proliferation in vivo and in vitro. The authors studied the effect of a sustained subconjunctival release of daunorubicin by way of a bioerodible polymer on the success of glaucoma filtration surgery in a rabbit model. METHODS: Daunorubicin was incorporated into the copolymer by compression molding. The resultant implant measured 3.0 mm in diameter, 1.0 mm in thickness, and 8.0 mg in weight. A posterior lip sclerectomy was performed in both eyes of 23 rabbits by the same surgeon. One eye was randomized to receive the disc with daunorubicin, whereas the fellow eye received a blank disk as a control. The appropriate polymer disk then was placed on the scleral surface immediately posterior to the sclerostomy site and the conjunctiva was closed. Intraocular pressures and slit-lamp biomicroscopy were recorded preoperatively, then every other day after surgery for 31 days. Intraocular pressure, bleb survival, and complications were evaluated. RESULTS: The decrease in intraocular pressure from baseline was significantly greater in the daunorubicin eyes than in the control eyes during postoperative days 5 through 25. Bleb survival was significantly longer in the daunorubicin eyes than in the control eyes (bleb failure in 91% of control eyes versus 22% of treatment eyes by day 13). There were no statistically significant differences between the daunorubicin-treated and control eyes regarding corneal clouding, lens clarity, cataract formation, or conjunctival injection. However, conjunctival erosions occurred in four daunorubicin-treated eyes. Histopathologic examination was performed 2 weeks after surgery on the eyes of three randomly selected rabbits. CONCLUSION: Daunorubicin in a bioerodible delivery system may potentially be a useful adjunct to glaucoma filtering surgery and requires further evaluation.

Animals↗
PubMedDate not supplied

[5-fluorouracil in the treatment of postoperative glaucoma].

INTRODUCTION: Standard filtering surgery in postoperative glaucoma in aphakic and pseudophakic eyes and eyes after failed filtering surgery is successful in 50% cases. The main cause of failure filtering surgery is scarring of the filtering bleb-fibroblastic proliferation at the subconjunctival episcleral interface [1, 2]. The use of antimetabolites such as 5-fluorouracil and Mitomycin C inhibits fibroblast proliferation and increases the success rate of filtering surgery, especially in postoperative glaucoma [3-6]. The exact dosage and frequency of administration to maximize success and minimize complications of treatment has not yet been determined [7]. METHODS: Fifteen patients (15 eyes) with medically uncontrolled postoperative glaucomas were included in the study. Clinical data are summarised in Table 1. All patients after standard trabeculectomy received 5 mg of 0.3 ml 5-fluorouracil subconjunctivally each day for 7 days. The mean 5-fluorouracil dose was 25.1 mg. Topical corticosteroid and cycloplegic eye drops were also instilled in all 15 eyes for 4 weeks after surgery. RESULTS: Successful control of IOP was achieved after a 5-fluorouracil filtering procedure in 13 of 15 eyes (86.6%), with a mean follow-up of 11.4 months. Two patients (13.4%) with uncontrolled glaucoma required cyclokryocoagulation in addition to antiglaucoma medications. Transscleral fibrosa and internal occlusive membrane were the primary cause of failure of filtration fistulas. Only one patient in the group of successful control of IOP required topical 0.5% Timolol (Table 1). Mean value of postoperative IOP was 13.53 mmHg. Most of the early complications such as corneal epitheliopathy, corneal epithelial defects and shallow anterior chamber, resolved without irreversible damage. Two eyes had transient maculopathy and choroidal detachment. There were no late complications, except progression of cataracta in one eye (Table 2). DISCUSSION: Our success rate in 5-fluorouracil treatment in postoperative glaucoma was 86.6%. The results of Fluorouracil Filtering Surgery Study Group revealed failure in 28% of eyes with 5-fluorouracil treatment compared to 60% of eyes in standard group without fluorouracil. We achieved better results in shorter follow-up. Short term complications related to 5-fluorouracil treatment such as corneal epithelipathy, recovered well with time. Long term complications caused by thin and cystic blebs: endophthalmitis, iridocyclitis, late bleb leaks, bleb encapsulated, were not recorded in our series. By comparing the results reported here with those previously reported [8-10] it looks like that certain long term complications can be reduced by adjusting the dose according to the clinical response. Weinrab et al. [10] reported similar successful surgical outcomes in refractory glaucoma, but these results cannot be compared directly, because of likely differences in such factors, as are the indications of surgical criteria for selection of specific surgical procedures, surgical technique and postoperative care. Some clinical reports have shown that Mitomycin C contributes to the increased success of filtering surgery in high risk glaucoma [11, 12], but 5-fluorouracil is still the golden standard among other antimetabolites.

Adult↗
PubMed1993

A releasable scleral-flap tamponade suture for guarded filtration surgery.

Postoperative complications of filtering surgery are generally associated with overfiltration. We describe a technique that employs an externalized releasable suture in partial-thickness filtering surgery. This suture acts as a tamponade on the anterior surface of the scleral flap, assisting in maintenance of anterior-chamber depth during the early postoperative period. After using this technique, anterior-chamber depths preoperatively and 1 day after surgery were compared in 35 phakic patients. A mean (+/- SD) decrease in anterior chamber depth of 4.6% +/- 12% was found on the first postoperative day. One patient had iridocorneal apposition. The mean intraocular pressure 1 day after surgery was 7.0 +/- 7.0 mm Hg, with one patent having an intraocular pressure of 28 mm Hg. This "tamponade suture" appears to be useful in maintaining the anterior chamber depth in the early postoperative period while permitting satisfactory filtration.

Adult↗