46.2.5  Nonpenetrating Surgery In SWS

Glaucoma

Recently, nonpenetrating glaucoma surgery has gained popularity. Because choroidal effusions following fistulizing surgery can occur in patients with SWS, nonpenetrating glaucoma surgery may offer a theoretical advantage; since there is no penetration of the anterior chamber during surgery, sudden intraoperative and postoperative hypotony may be avoided. A single case study reported reduction of IOP from 30 to 15 mmHg 6 months postoperatively. No intraoperative or postoperative complications occurred [14]. Further study is needed regarding the use of this technique in this population.

Summary for the Clinician

››There are no large, long-term studies that dictate the optimal management of glaucoma in patients with SWS.

››SWS-associated glaucoma can be more difficult to control than other forms of glaucoma and there is a higher risk of surgical complications.

››Glaucoma in SWS is less responsive to medical therapy. Aqueous suppressants and miotics work best.

››Early-onset glaucoma in SWS is caused by angle abnormalities. Goniotomy or trabeculotomy is typically the first line of therapy in these cases but these procedures are usually less successful than in primary congenital glaucoma.

››For juvenile or later-onset glaucoma, topical medications are typically first-line therapy but they frequently fail. The next step in treatment is usually a trabeculectomy (often with limited success because of the age group being operated on) or glaucoma drainage device (results comparable to other diseases).

››Primary combined trabeculotomy-trabeculec- tomy has been successful; however, it is not clear that it is more successful than trabeculectomy. Cycloablation is usually reserved for SWS patients who have failed other medical and surgical interventions.

››Nonpenetrating surgery has been done for glaucoma in SWS patients. Theoretically, since there is no sudden drop in IOP during the procedure there may be less risk of choroidal effusions.

46.3  What Problems Should Be

Anticipated in the Management

of SWS Glaucoma?

In individuals with SWS and glaucoma, there is a higher nonresponse rate to medical therapy, especially if the glaucoma onset is early. Thus surgical therapy is often needed to lower the IOPs to a target range.

The main concern when managing glaucoma in SWS is related to intraoperative and postoperative complications. Several early publications reported complications of incisional surgery in these patients, including expulsive choroidal hemorrhages and sudden intraoperative choroidal effusions. These complications are thought to be related to elevated episcleral venous pressure. Expulsive choroidal hemorrhages may also be related to fragile choroidal vascular walls. Several precautions have been proposed to reduce the risk of these complications; they include reducing IOP immediately prior to surgery with hyperosmotic agents or treating the choroidal hemangioma with radiotherapy prior to intraocular surgery.

Choroidal effusions have also been reported with intraocular surgery and may be secondary to a rapid shift of fluid from choroidal capillaries to the suprachoroidal space in the face of a sudden IOP drop and elevated episcleral and choroidal venous pressure. Development of a choroidal effusion intraoperatively is signaled by sudden shallowing of the anterior chamber. If this occurs, drainage may be indicated via inferior linear sclerotomies, located 5–6 mm posterior to the limbus. If surgery is then planned for the second eye of a patient who has developed intraoperative choroidal effusions in the first eye, placement of a prophylactic sclerotomy may be indicated.

Others recommend the regular placement of posterior sclerotomies prior to entry into the eye of an SWS patient to reduce these risks, especially if the eye has extensive choroidal hemangiomas. Sclerotomies allow suprachoroidal effusions to drain out of the eye as they form. However a study reviewing 34 glaucoma filtering surgeries without posterior sclerotomy on 17 patients showed no intraoperative choroidal effusions, detachments or hemorrhages. Posteroperatively, choroidal effusions occurred in six individuals but all were transient [7].

Another way to decrease the risk of choroidal effusion is to limit intraoperative hypotony and thereby reduce the amount of time for expansion of the vascular compartment. This goal can be achieved by reducing the time the eye is open to atmospheric pressure