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Adequate scleral bed and flap thickness essential in mini glaucoma shunt implantation, surgeon says
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DANA POINT, Calif. — Ensuring adequate thickness of the scleral bed and the scleral flap were two surgical tips offered here by a surgeon experienced in implanting the Ex-PRESS mini shunt from Alcon. Paying attention to the angle of entry is also important.
The procedure is basically a modified trabeculectomy intended to standardize the fistula size to 50 µm to control flow, Sameh Mosaed, MD, said in a presentation at the American Glaucoma Society meeting. It begins as a trabeculectomy normally would, but the surgeon must ensure that the scleral flap is thick enough to support the device.
Using a 25-, 26- or 27-gauge needle, the surgeon then creates the pre-incision site, inserting the needle at the lower end of the blue-gray zone and entering parallel to the iris. The device is inserted at this site, and the surgeon closes as normally done. The procedure differs in that no sclerectomy or iridectomy is done.
"These two points theoretically decrease postoperative inflammation and perhaps increase surgical success," Dr. Mosaed said.
- Disclosure: Dr. Mosaed reports financial relationships with Alcon, Allergan and Heidelberg Engineering.
Dr. Mosaed points out several important clinical factors for successful implantation of the Ex-PRESS glaucoma mini shunt (Alcon). If the scleral bed is too thick, it may be more difficult to seat the device through the 25- to 27-gauge incision; if the bed is too thin, there may not be adequate support, possibly leading to the shunt moving inward or outward postoperatively. If an irregular incision is created with resultant peri-shunt flow, the risk for hypotony may increase. If the scleral flap is too thin, there is a risk of too much flow and erosion of the device through the conjunctiva; if the flap is too thick, it may be more difficult to establish flow from the external aspect of the mini shunt, possibly leading to inadequate IOP lowering. While proper dimensions of the scleral flap and bed are relatively easy to achieve during surgery, patient variables may skew the consistency that the mini shunt brings to filtering surgery.
– Robert Noecker, MD, MBA
Vice Chair,
UPMC Eye Center
Disclosure: Dr. Noecker is a consultant, speaker and/or
lecturer for Allergan, Alcon, Lumenis, Endo Optiks and Carl Zeiss Meditec.