The filtering, clear-cornea diathermal keratostomy: a minor Danish multicenter study.

PURPOSE: Is the new micropenetrating, clear-cornea procedure, intrastromal diathermal keratostomy (IDK), an alternative to the intricate "modern trabeculectomy"? METHODS: Prospective multicenter study. Four surgeons from 4 Danish eye departments attended an IDK course and subsequently decided when to start their consecutive IDK series. The data were analyzed centrally. Injection of preoperative, subconjunctival doses of mitomycin C (MMC) was recommended according to risk-of-failure. A total of 54 eyes from 48 patients with advanced and complicated glaucomas (mean age 65 y) and preoperative mean intraocular pressure (IOP) of 29 mm Hg were studied. RESULTS: At 10 months (range: 3 to 34 mo) the total success rate, employing traditional IOP success criteria (IOP< or =18 mm Hg and postoperative IOP decrease > or =30%), was 87% (47 of 54 eyes). In the 69% (37 of 54 eyes) without medication, the final IOP+/-SD was 11+/-3.5 mm Hg. Employing new IOP success criteria (IOP< or =15 mm Hg and postoperative IOP decrease> or =30%) for severe glaucoma (cup/disc ratio> or =0.8) and traditional criteria for moderate glaucoma (cup/disc ratio< or =0.7) the success rates were 76% and 80% and the mean postoperative IOP+/-SD were 10+/-2.5 mm Hg and 13+/-2.5 mm Hg, respectively. No serious complications (malignant glaucoma, endophthalmitis) were seen. The success rate for the most experienced and the less experienced surgeons, with risk-of-failure factors per eye of 1.3 and 1.2, was similar at 88% and 86%, respectively. The "knife time" for the experienced surgeon averaged 15 minutes (range: 10 to 20 min). The success rate (traditional criteria) after IDK revision with internal needling was 69%. CONCLUSIONS: MMC IDK seems to be simpler and quicker than the modern trabeculectomy, and with similar success rate and safety. Revision by internal needling is easy and efficient. Thus, MMC IDK may be a valid alternative and may also be recommended after failed MMC trabeculectomy, replacing shunting. Randomized, controlled studies are indicated.

Intrastromal diathermal keratostomy: a new micropenetrating clear-cornea glaucoma procedure.

PURPOSE: The filtering intrastromal diathermal keratostomy (IDK) was developed to comply with the call for a low postoperative intraocular pressure (IOP) and a bleb morphology without a thin, cystic appearance. PATIENTS AND METHODS: A diathermal microkeratostomy (150 to 200 microm) was created into the anterior chamber, anterior to the Schwalbe line through the floor of a surgical corneoscleral tunnel incision into the subconjunctival space. A newly developed, bipolar diathermal microneedle was used to create the keratostomy, replacing the Holmium laser used previously. Subconjunctival injections of 3 microg mitomycin C were used in each eye 1 week before the IDK to obtain maximum antiproliferative effect at the time of the operation. Nine patients (10 eyes) with complicated, refractory primary and secondary open-angle glaucoma are discussed. RESULTS: Histologic examination of the IDK and clinical postoperative ultrasound biomicroscopy showed an optimal appearance of the diathermal microkeratostomy. After 34 months (range 24 to 42 mo) the mean IOP was 11 mm Hg (SD+/-3, range 6 to 16) without medication in all 10 eyes. IDK revision with internal needling of postoperative subconjunctival fibrosis through the tunnel incision was performed in 5 eyes after an average of 3 months (range 0.2 to 7 mo). After 33 months (range 19 to 38 mo), the postrevision mean IOP was 10 mm Hg (SD+/-2, range 8 to 14) without medication in all 5 eyes. All 10 eyes showed noncystic diffuse blebs with optimal spongy subepithelial morphology: in 2 eyes the blebs were totally avascular and in 8 eyes they were relatively avascular. CONCLUSIONS: The preliminary results of the new clear-cornea IDK seem promising because of postoperative IOP of about 10 mm Hg despite a low dose of mitomycin C and noncystic bleb morphology.