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.