membrane with cryotherapy after the eye has been filled with air. Yet another approach involves excision of involved tissues, a penetrating keratoplasty, and implantation of a glaucoma shunt.251 One case report using adjunctive 5-fluorouracil, both for glaucoma control and in an attempt to control the epithelialization, was unsuccessful. Many other techniques have been described in the past for treating epithelial ingrowth, including X-radiation, beta-irradiation, curettage with alcohol, and photocoagulation.252–254 These have been largely abandoned as ineffective. Immunotoxin has been shown to inhibit epithelial proliferation in tissue culture;255 perhaps an agent like this may find some use in the future in this very frustrating condition.

All of the current techniques have been reported to salvage some eyes with epithelial downgrowth and even to maintain good vision in a few cases. However, recurrences of the downgrowth are common, and surgery is frequently associated with complications that include corneal edema, chronic inflammation, macular edema, and phthisis bulbi.The results of treatment are better if the condition is diagnosed early. However, it must be stressed that preventing epithelial downgrowth is far more effective than treating established disease. Surgical and traumatic wounds must be cleaned of epithelial tissue fragments and foreign material and then sutured meticulously.

Fibrovascular ingrowth

Fibrovascular tissue can grow into an eye if there is an open wound after penetrating trauma or surgery. Fibrovascular ingrowth occurs more frequently if the trauma or surgery is associated with hemorrhage, inflammation, or incarcerated tissue.256–258 Fibrovascular ingrowth can occur from pars plana incisions, as well as from more anterior ones.259 In some cases the ingrowth resembles a vascular stalk that enters the eye through an old wound and then fans out over the anterior segment. In other cases the ingrowth forms a gray-white membrane posterior to the corneal endothelium, without an obvious entry site or a vascular stalk. The membrane may have an interlacing pattern of gray fibers that has been compared to woven cloth.260 Various authorities have attributed the invading fibroblasts to the subconjunctival connective tissue, corneal stroma, limbal tissue,261 and metaplastic endothelium.262 The invading fibrovascular tissue grows over the corneal endothelium, anterior iris surface, vitreous face, and angle, where it contracts to form PAS. On occasion the membrane can also attach to the retina and cause a traction detachment.

Fibrovascular ingrowth usually causes glaucoma when the membrane covers the angle and then contracts to form peripheral anterior synechiae. Other factors contributing to the glaucoma include uveitis, pupillary block, and underlying trauma. In many ways, fibrovascular ingrowth resembles epithelial downgrowth, although it is less virulent in its course.263

It is far better to prevent fibrovascular ingrowth than to treat the condition once established. In the past this condition was a common finding in eyes enucleated after cataract surgery or trauma.264 With current microsurgical techniques, fibrovascular ingrowth is encountered far less often.

The glaucoma associated with fibrovascular ingrowth is usually managed by medical therapy. In some cases posterior glaucoma drainage device implantation or cyclophotocoagulation is required to control IOP. On occasion it is possible to excise the fibrovascular tissue, including the fistula at the old wound. However, this approach is not suitable for most eyes with fibrovascular ingrowth because the involvement of the anterior segment is too extensive.

Furthermore, the poor visual prognosis usually does not warrant such aggressive surgery in most cases. Cyclodestructive procedures can often alleviate painfully high IOPs.

Glaucoma has been reported from proliferation of iris melanocytes across the angle and the remainder of the anterior segment.265 This type of glaucoma is extremely rare.

Flat anterior chamber

A flat anterior chamber after penetrating trauma or surgery can lead to the formation of PAS and secondary angle-closure glaucoma without pupillary block (Table 16–1; Fig. 16–9). The development of synechiae is related to the duration of the flat anterior chamber and the degree of inflammation of the eye. There are a number of reports on delayed re-formation of the anterior chamber after cataract extraction. In most of these studies secondary

angle-closure glaucoma was common if the anterior chamber was flat for 5 days or longer.267–269 Flat anterior chambers are encoun-

tered far less often with modern microsurgical cataract techniques. However, flat anterior chambers occur not uncommonly after filtering operations, and they are often allowed to persist for a few to several days before re-formation is attempted. Flat anterior chambers also may occur in association with malignant glaucoma and penetrating keratoplasty.

Following re-formation of a flat anterior chamber, the residual secondary angle-closure glaucoma is treated with standard medical therapy. Often patients respond better to medical treatment than would have been predicted by the extent of the angle closure.This suggests that some of the trabecular meshwork is functional behind the apparent PAS; that is, the synechiae are bridging rather than closing the angle if the duration of tissue approximation is short enough. If medical treatment is inadequate, a laser trabeculoplasty can be considered if at least one-third to one-half of the angle is open. However, the clinician must be aware that a sustained postlaser IOP rise may necessitate filtering surgery. Other alternatives include filtering operations, cyclodestructive procedures, and surgical goniosyneechialysis of the PAS.270

Inflammation

Inflammation can produce glaucoma through a variety of mechanisms, including increased viscosity of the aqueous humor, obstruction of the trabecular meshwork by inflammatory cells and debris, scarring of the outflow channels, elevated episcleral venous pressure, forward displacement of the lens–iris diaphragm, and pupillary block from posterior synechiae. Inflammation can also produce angleclosure glaucoma without pupillary block when the peripheral iris swells as a result of the inflammatory process, when precipitates or exudates in the angle contract to form PAS, or when there is forward rotation of the ciliary body. These can occur after surgery or trauma, in idiopathic inflammatory conditions, or with specific uveitis entities such as interstitial keratitis,271 sarcoidosis,272 ankylosing spondylitis,273,274 pars planitis,275 and juvenile rheumatoid arthritis, particularly the pauciarticular variety.276–279 Peripheral anterior synechiae form more readily in eyes with shallow anterior chambers and in eyes afflicted with chronic granulomatous inflammatory disease.

Secondary angle-closure glaucoma without pupillary block is usually managed with medical therapy. It is crucial that residual inflammation be suppressed with corticosteroids. However, the ophthalmologist must keep in mind the possibility of inducing corticosteroid glaucoma. Patients are often more comfortable

Fig. 16–9  Histopathology of anterior synechia formation following postoperative flat anterior chamber.

(Courtesy of William H Spencer, MD.)

with the addition of cycloplegic agents which may, by dilating the pupil, prevent pupillary block from posterior synechiae formation. Virtually all topical glaucoma agents are used to control IOP, with two guarded exceptions. Miotics may be helpful in the pseudophakic eye if it is quiet, but they are usually counterproductive in the presence of persistent inflammation. Similarly, prostaglandins should be used with caution because they may occasionally precipitate an inflammatory reaction.280 Hyperosmotic agents are administered on occasion for acute elevations of IOP.

If medical therapy fails to control IOP, filtering surgery must be considered. Because standard filtering surgery is less likely to be successful in inflamed eyes (and these patients are often young people), filtering surgery with adjunctive antimetabolite therapy or glaucoma drainage devices such as the Molteno, Baerveldt, or Ahmed implants should be performed. In children with inflammatory

disease the prospects for successful filtering surgery are further reduced by rapid healing, low scleral rigidity, and the increased thickness of Tenon’s capsule.281 A few authorities have used a modified goniotomy procedure – trabeculodialysis – to treat children with inflammation and glaucoma. A goniotomy knife is used to depress the iris and lyse any PAS present.The trabecular meshwork is then incised below Schwalbe’s line, and the trabecular tissues are retracted further.282,283

Penetrating keratoplasty

Angle-closure glaucoma can develop after penetrating keratoplasty, from mechanisms including pupillary block, postoperative inflammation, or a flat anterior chamber from a wound leak. The severity of the glaucoma is generally related to the extent of the synechial closure. The incidence of postkeratoplasty angle closure is reduced by performing one or more iridectomies, closing the wound meticulously, using a graft slightly larger than the recipient bed, and administering corticosteroids postoperatively.284–286 However, in some cases the iris becomes attached to the corneal wound, and it is pulled forward in progressive fashion. Glaucoma of one sort or another is a complication in about 20% of penetrating keratoplasties.287

Most cases of postkeratoplasty angle-closure glaucoma without pupillary block can be managed with standard medical treatment. Many of these eyes are aphakic and respond well to cholinesterase inhibitors, -blockers, -adrenergic agonists, prostaglandins, and carbonic anhydrase inhibitors. If pupillary block is contributing to the glaucoma, a laser iridotomy should be performed. Laser trabeculoplasty may be helpful, provided that at least one-third to onehalf of the angle is open.288 When medical treatment fails to control the glaucoma, filtering surgery with mitomycin-C can be successful if conjunctiva is not heavily scarred.289 However, the surgeon must proceed with care to avoid damage to the corneal graft. Filtering surgery alone often fails.290 A posterior glaucoma drainage device