In most cases of newly diagnosed retinal detachment, IOP is low. However, glaucoma may become apparent later or may be detected in the fellow eye. It is postulated that retinal detachment lowers IOP by inducing inflammation and reducing aqueous humor formation.

It is also possible that aqueous humor may be eliminated by flowing through the retinal hole into the subretinal space.338,340 Campbell

has described an extreme example of this phenomenon, which he calls the iris retraction syndrome.341 In this syndrome, a patient with a rhegmatogenous retinal detachment, secluded pupil, iris bombé, and angle-closure glaucoma develops hypotony and iris retraction when aqueous formation is reduced pharmacologically. Campbell postulates that the induced reduction in aqueous formation allows most of the aqueous humor to go posteriorly through the retinal hole.

Schwartz Syndrome

In a minority of cases, retinal detachment causes a peculiar increase in IOP that is referred to as Schwartz syndrome.342 In this syndrome, rhegmatogenous retinal detachment is associated with elevated IOP, diminished outflow facility, open angles, and cell and flare in the aqueous humor.343 When the retinal detachment is repaired, the

IOP and outflow facility return to normal.342 It has been postulated that the glaucoma is related to angle recession,333,342,344

inflammation, pigment granules released by the retinal pigment epithelium,344 and glycosaminoglycans synthesized by the photo­ receptors.345 One additional suggestion is that photoreceptor outer segments migrate through the retinal hole and obstruct the trabecular meshwork. The IOP can vary from mildly elevated to very high, and medical treatment is rarely successful in controlling the condition. Schwartz syndrome must be distinguished from glaucoma and non-rhegmatogenous retinal detachment caused by an undetected malignant melanoma.

Glaucoma after vitrectomy

Elevated IOP has been reported in 20–26% of eyes after vitrectomy.346,347 This occurs through a variety of mechanisms (Box

18 2). Because most of these entities are discussed in detail elsewhere in this book, only a few general remarks are offered here.

It is important to monitor IOP postoperatively by applanation tonometry because the accuracy of indentation tonometers is affected by scleral surgery. In addition, intraocular gas may interfere with pressure measurements using a Schiøtz tonometer.

Liquid silicone is sometimes injected into the vitreous cavity in cases of complicated retinal detachment. The silicone and mac-

rophages laden with silicone may obstruct the trabecular meshwork.348,349 The silicone may also cause pupillary block, which can be prevented by an inferior iridectomy at the time of surgery.350,351

The iridectomy has a somewhat greater chance of closing in these cases; t-PA helped keep the peripheral iridectomy open in a case reported by MacCumber and co-workers.352 In many cases of intravitreal silicone injection, IOP is depressed by persistent inflammation, hyposecretion, retinal detachment, or cyclitic membrane formation.

Glaucoma with uveitis

Inflammation can produce glaucoma through a variety of mechanisms, including (1) increased viscosity of aqueous humor;

(2) obstruction of the trabecular meshwork by inflammatory cells and debris; (3) swelling and dysfunction of the trabecular meshwork; (4) liberation of active substances such as prostaglandins; (5) scarring of the outflow channels; (6) development of a cuticular endothelial membrane over the angle; (7) neovascularization; (8) elevation of episcleral venous pressure; (9) forward displacement of the lens–iris diaphragm (uveal effusion); (10) pupillary block, and (11) formation of peripheral anterior synechiae. Elevated IOP can occur with any type of ocular inflammatory disease but is more common in the chronic forms than in the acute forms. In most ocular inflammatory diseases, aqueous humor formation is reduced and IOP is low.353 If outflow facility is reduced as well, however, IOP can be elevated. Because of this dual involvement of aqueous humor inflow and outflow, eyes with active inflammatory disease often suffer wide swings of IOP, and glaucoma may be missed if only occasional pressure measurements are made.Additionally, these patients can be extremely sensitive to medications (e.g., acetazolamide) that decrease aqueous production. In sensitive patients, the pressure can drop from over 50 mmHg to under 5 mmHg with a single dose. Careful individual titration is needed to arrive at the proper medication regimen.

The treatment of glaucoma associated with ocular inflammatory disease depends on the underlying condition, but in most situations, inflammation is suppressed by some combination of topical, systemic, and periocular corticosteroids. During this treatment the ophthalmologist must be aware of the possibility of corticosteroidinduced IOP elevations. Steroid glaucoma is a particular problem in patients on long-term corticosteroid therapy for chronic or recurrent uveitis. A variety of other medications may be employed to reduce inflammation, including cycloplegic agents, non-steroidal antiinflammatory drugs, and immunomodulators such as methotrexate, azathioprine, and chlorambucil. Elevated IOP is generally managed

Box 18-2  Glaucoma after vitrectomy

Pre-existing glaucoma

Angle recession

Ghost cell

Primary open-angle glaucoma

Pigmentary glaucoma

Associated with intraocular hemorrhage

Hyphema

Ghost cell

Hemolytic

Hemosiderosis

Related to lens material

Phacolytic

Lens particle

Phacoanaphylactic

Neovascular

Inflammatory

Corticosteroid induced

Intraocular gas or liquid

Air

Viscoelastic substances

Perfluorocarbons

Silicone

Modified from Wilensky JT, Goldberg MF, Alward P: Glaucoma after pars plana vitrectomy, Trans Am Acad Ophthalmol Otolaryngol 83:114, 1977.

by topical and systemic glaucoma medications as needed. Miotics are usually avoided because they increase pain and congestion and may promote the development of posterior synechiae. Prostaglandins such as latanoprost are used with caution in uveitic patients because they could theoretically exacerbate signs and symptoms that might be confused with the underlying inflammatory condition.

Argon laser trabeculoplasty (ALT) is not very helpful in eyes with active inflammation. It may cause a mild acute anterior uveitis in some patients and may also lead to peripheral anterior synechiae. For this and other reasons, most surgeons avoid ALT in patients with uveitis. Surgery should be avoided in eyes with active inflammation, but if a filtering procedure is required, inflammation should be suppressed as much as possible by topical and systemic corticosteroid treatment. Inhibitors of scarring such as mitomycin-C354 or 5-fluorouracil (5-FU)355 are often useful in this situation, as are tube-shunt devices such as the Ahmed234 or Molteno valve.354 In a young individual with uveitis and secondary glaucoma, an Ahmed, Molteno, or Baerveldt implant may be the preferred first procedure since trabeculectomy, even with antifibrosis agents, is unlikely to work. Eyes with active inflammation sometimes require cyclodestructive procedures, although the risk of exacerbating inflammation makes this option worrisome.356

A wide variety of inflammatory diseases are associated with secondary open-angle glaucoma. This section discusses a few of the more common entities

Fuchs’ Heterochromic Iridocyclitis

Fuchs’ heterochromic iridocyclitis is a chronic but relatively mild form of anterior uveitis associated with cataract and glaucoma.357–360

Approximately 90% of the cases are unilateral, and the disease has its onset in the third and fourth decades of life.361 Men and women

are affected in equal numbers. Patients are generally asymptomatic until they develop cataract or vitreous opacities.The physical findings in this syndrome include minimal cell and flare, fine round or stellate keratic precipitates, fine filaments on the endothelium between the keratic precipitates, a patchy loss of the iris pigment epithelium, hypochromia, grey-white nodules on the anterior iris, a few opacities in the anterior vitreous, and chorioretinal scars that resemble toxoplasmosis.361–364 Heterochromia may be seen in about 70% of Caucasian eyes.365 However, if the iris is dark in color, heterochromia may be present in only 25% and the diagnosis may rest on the keratic precipitates and areas of iris atrophy.366 Gonioscopy reveals fine vessels that bridge the angle and can bleed with minimal trauma, such as paracentesis.367 Fluorescein angiog-

raphy of the iris demonstrates ischemia, leakage, neovascularization, and delayed filling of the vessels.368,369

No specific cause has been identified although toxocariasis and

toxoplasmosis have both been implicated by associated antibody findings.370–372 Rubella virus and antibodies against rubella virus

have been found in the aqueous humor of young patients with Fuchs’ heterochromic iridocyclitis. Furthermore, the incidence in the United States has significantly declined since the advent of the rubella vaccination program.373 This evidence strongly suggests that rubella infection plays a role in at least some cases of Fuchs’.

Increased IOP has been reported in 13–59% of patients with Fuchs’ heterochromic iridocyclitis.364,374 One study, albeit with fairly

small numbers, reported an increased glaucoma prevalence among

black patients, with 38% (5 of 13) of blacks having glaucoma compared with only 11% (6 of 54) of whites.375 The cause of the glau-

coma is not clear, but the angle is open and no peripheral anterior

synechiae are seen. It is postulated that the inflammation eventually produces scarring and dysfunction of the outflow channels. Histologic examination of a few surgical specimens has confirmed

the inflammation and scarring of the trabecular meshwork and revealed an inflammatory membrane over the angle.376,377

Glaucoma may also be seen following cataract surgery, neovascularization, or over-zealous treatment with corticosteroids. The inflammatory component of Fuchs’ heterochromic iridocyclitis is generally unresponsive to corticosteroid treatment, part of which may be explained by a possible infectious etiology. Elevated IOP is treated with medical therapy, but the results are often disappointing, with only about a quarter of patients achieving satisfactory control.378 In the past, the results of conventional filtration

surgery were also poor, with less than half of patients achieving control.364,379 Use of wound-healing retardants such as 5-FU and

mitomycin-C has improved surgical outcomes considerably, with

success rates as high as 72%.378 Cataract surgery with in-the-bag intraocular lens implantation is usually successful.380,381

Glaucomatocyclitic Crisis

Glaucomatocyclitic crisis, also called the Posner-Schlossman syndrome, is usually seen in young to middle-aged adults and consists of recur-

rent episodes of mild anterior uveitis and marked elevations of IOP.382–387 Generally this condition is unilateral, but both eyes can

be affected at different times.385 Patients have relatively few symptoms considering the height of their IOPs, but they may complain of slight discomfort, slight blurring of vision, or halo vision. The prevalence of this condition is low; for example, in Finland, glaucomatocyclitic crisis represents 0.4% of all uveitis seen in one clinic.388

The physical findings during an episode of glaucomatocyclitic crisis include mild ciliary flush, a dilated or sluggishly reactive pupil, corneal epithelial edema, IOP in the range of 40–60 mmHg, decreased outflow facility, open angles, faint flare, and 1–20 fine keratic precipitates. The keratic precipitates may not appear for 2 or 3 days after the IOP has risen, which may obscure the diagnosis. It is postulated that the elevated IOP is caused by inflammation of the trabecular meshwork, perhaps mediated by prostaglandins.389 There is also evidence of an association between herpes simplex virus and glaucomatocyclitic crisis, but the significance of this association is unknown.390 The crises last several hours to a few weeks. Some patients experience one or two episodes in their lives, whereas other patients experience recurrent crises for many years. As a rule, the frequency of recurrences diminishes with age.

For many years it was accepted that glaucomatocyclitic crisis never caused optic nerve cupping or visual field loss and that aqueous humor dynamics were normal between episodes. It is now clear, however, that some patients with glaucomatocyclitic crisis have

abnormal aqueous humor dynamics between episodes and that some have underlying POAG.385,387 Furthermore, some patients develop

optic nerve cupping and visual field loss because of repeated crises or underlying POAG.384,385,387 Indeed, some patients develop glau-

comatous damage years after initial symptoms appear; therefore, all patients should be monitored indefinitely.391

Glaucomatocyclitic crisis is usually treated with topical corticosteroids and topical and systemic glaucoma medications. As with all types of uveitis, miotics are avoided. Apraclonidine 1% has been found to be particularly effective.392 Some authorities recommend the administration of systemic or topical non-steroidal anti-inflammatory agents because of increased aqueous humor prostaglandin levels. Because the episodes are self-limited, moderate