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Modified nonpenetrating glaucoma surgery shows promise
At 6 months, IOP was controlled without topical glaucoma medications in the majority of patients.
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A nonpenetrating glaucoma procedure that involves the use of a surgical drill may be a less complex surgical alternative to other nonpenetrating glaucoma procedures, according to a study presented here.
Jorge L. Alió, MD, PhD, and Jose L. Rodriguez, MD, of Alicante, Spain, presented the results of a pilot study evaluating milling trabeculoplasty at the European Society of Cataract and Refractive Surgeons annual meeting.
Dr. Alió said the procedure uses a notched hemispherical metallic tip attached to a high-velocity milling drill capable of 10,000 to 12,000 rpm, similar to the drill used in a dacryocystorhinostomy or for polishing the corneal bed after foreign body removal.
The concept is for the high speed of the drill tip to polish as it removes tissue. The procedure avoids cutting into the sclera, and the thickness of the remaining scleral thickness can be refined. A separate tip coated with diamond powder is also available for more delicate maneuvers, such as removing debris, and can enhance the creation of a smooth bed, he noted.
Such a procedure would be safer and faster than conventional nonpenetrating procedures, and it can produce comparable results, he said. In the study, patients had roughly a 40% mean decrease in IOP without the addition of a collagen device or adjunctive use of antimetabolites, such as mitomycin C.
Pilot study
The pilot study included 16 eyes of 13 patients with a mean age of 50.3 ± 7.5 years. All patients had primary open-angle glaucoma that was uncontrolled medically. No implants, mitomycin C or viscocanalicular injections were used in any of the procedures.
In the study, eight eyes were treated with milling trabeculoplasty only and eight eyes received milling trabeculoplasty combined with phacoemulsification for cataract removal.
Peribulbar anesthesia was used in all cases. Preoperatively, topical oxibuprocaine 0.2% was applied to the eyes, and a fornix-based conjunctival flap was used.
For the milling procedure, a rectangular scleral flap approximately 4-mm long and 4-mm wide was created, followed by lamellar dissection and milling of the tissue above the trabecular area. Schlemm’s canal was then cannulated, and the anterior tissue was refined.
Dr. Alió noted that at this stage Schlemm’s canal can be deroffed and the inner wall stripped if there is reduced outflow. However, the trabeculo-Descemet’s membrane should remain intact.
Once filtration was visible, the flap was repositioned and sutured in place using two 10-0 sutures. Tobradex eye drops can be used three times a day for 1 month postop.
Results
According to the study, milling trabeculoplasty was successful in reducing IOP to target levels in 62.5% of all eyes at 6 months follow-up, with the remaining 37.5% using a single topical anti-glaucoma medication.
At 6-month follow-up, 87.6% of eyes had an IOP of 18 mm Hg or less, and 12.5% had an IOP of 24 mm Hg or less.
Dr. Alió noted that the procedure created a diffuse functioning bleb in 87.6% of eyes, a localized functioning bleb in 6.3% and a fibrotic bleb in 6.3%.
There was one case of microperforation, one case of poor IOP control at 6 months postop, and one eye required another operation. There was one case of hypotony and one case of bleb fibrosis.
According to the study, the average time required for surgery for both groups was 10.5 ± 2.6 minutes, ranging from 8 to 15 minutes.
Patients treated with milling trabeculoplasty only experienced a mean reduction in IOP of 46.3% at 1-month postop and 55.7% at 6 months.
Preoperatively, patients in the milling trabeculoplasty only group had mean IOP of 27.6 ± 10.1 mm Hg. This decreased to a mean of 14.7 ± 7.1 mm Hg at 1-month follow-up, 14.6 ± 2.4 mm Hg at 3 months, and 15.4 ± 10.6 mm Hg at 6 months.
Patients who underwent milling trabeculoplasty combined with phacoemulsification experienced a mean IOP reduction of 31.1% at 1 month and a 25.3% at 6 months postop.
Preoperatively, patients in the combined procedure group had a mean IOP of 21.7 ± 4.6 mm Hg, which decreased to a mean of 15 ± 1.5 mm Hg at 1-month follow-up, 14.6 ± 2.4 mm Hg at 3 months and 16.2 ± 3.4 mm Hg at 6 months.
For Your Information:
Jorge L. Alió, MD, PhD, can be reached at Avda, Denia 111, 03015 Alicante, Spain; +34-965-150-025; fax: +34-965-151-501; e-mail: jlalio@oftalio.com.