59.3  How Can I Manage Late Hypotony Due to a Scleral Melt?

A scleral melt will present with hypotony but the actual melt may not be realized until one is in the operating room, and a full thickness hole is exposed by dissection of the conjunctiva. Treating a scleral melt requires careful preparation. If done poorly, hypotony may persist. If done properly, IOP may rise with ensuing glaucoma. Repair requires fresh conjunctiva and a scleral graft or tutoplast patch graft. I approach this with a traction suture through the superior cornea, a paracentesis to place viscoelastic to firm up the eye, excision of necrotic/ischemic conjunctiva or scleral flaps, placing a donor scleral graft, followed by water-tight conjunctival closure. The scleral flap and adjacent sclera can be very friable and difficult to suture in cases of melt. Extra-long passes of the suture must be made to anchor sutures to normal tissue. Nondissolving suture should be used, as tension over the patch graft will be maintained for a much longer period of time.

Late onset hypotony is often more insidious in effect and more complicated to treat. It usually is a result of ischemic, necrotic conjunctiva, a scleral melt, or a combination of the two problems. The use of antifibrotics, especially mitomycin, has contributed greatly to this problem by irreversibly damaging cell function. Clinically, these patients present with decreased acuity from hypotonyinduced complications, including maculopathy and shrinkage­ of the globe. More extensive conjunctival dehiscence or thinning will require surgical revision either with fresh tissue from above or grafting. A scleral melt may necessitate a scleral patch graft. Autologous blood injection is ineffective in this situation.

Summary for the Clinician

››Additional antifibrotics should be avoided.

››Tight closure over the area of scleral melt is necessary using either a scleral patch graft or pericardial patch graft to create a new scleral wall.

››Suture bites should include healthy scleral tissue of the patient’s eye.

››Good conjunctival coverage is also necessary

– a conjunctival autograft can be used in case of scarred or inadequate conjunctiva.

››Inadequate closure will result in continued hypot­ ony whereas successful closure can result in very high pressures again.

59.4  Which Patients Are at Risk

for Hypotony?

In the early postoperative period, patient groups particularly at risk for hypotony include the elderly, aphakes, those with systemic vascular disease (such as hypertension or diabetes) or prior vitrectomy, and patients on anticoagulants. Sudden lowering of IOP, especially in the high risk patient, may result in complications, such as shallow or flat anterior chambers and choroidal effusions. A less common but more serious complication would be an acute or delayed choroidal hemorrhage causing profound visual loss and severe ocular pain [6].

Summary for the Clinician

››Risk factors for hypotony include the elderly, aphakes, prior vitrecomy, and systemic vascular disease.

References

 1. Jampel HD, Musch DC, Gillespie BW, et al. (2005) Perioperative complications of trabeculectomy in the collaborative initial glaucoma treatment study (CIGTS). Am J Ophthalmol 140:16–22.

 2. WuDunn D, Ryser D, Cantor LB (2005) Surgical drainage of choroidal effusions following glaucoma surgery. J Glaucoma 14:103–108.

 3. Costa VP, Arcieri ES (2007) Hypotony maculopathy. Acta Ophthalmol Scand 85:586–607.

 4. Francis BA, Wang M, Lei H, et al. (2005) Changes in axial length following trabeculectomy and glaucoma drainage device surgery. Br J Ophthalmol 89:17–20.

 5. Egrlimez S, Ates H, Nalcaci S, et al. (2004) Surgically induced corneal refractive change after glaucoma surgery: Nonpenetrating­ trabecular surgeries versus trabeculectomies. J Cataract Refract Surg 30:1232–1239.

 6. Tuli SS, WuDunn D, Ciulla TA, et al. (2001) Delayed suprachoroidal hemorrhage after glaucoma filtration surgery. Ophthalmology­ 108:1808–1811.