PHACOLYTIC GLAUCOMA

Lens protein is normally sequestered within the lens capsule. With age and the development of cataract, the protein composition of the lens is altered to components with heavier molecular weight. If these soluble molecules leak through what grossly appears to be an intact capsule, they can obstruct the trabecular meshwork. The lens protein also stimulates inflammation and a macrophage response. The macrophages engulf the lens protein and may further obstruct the outflow channels ( Fig. 18-7 ). Protein of heavy molecular weight is not seen in infants and children, possibly explaining the absence of phacolytic glaucoma in young patients with cataract.

Phacolytic glaucoma with bloated macrophages and lens material obstructing the trabecular meshwork.

Phacolytic glaucoma is usually seen in older patients, who usually have a history of poor vision in the eye for months or years. The patients we have seen with this condition have often been from areas with little access to health care such as inner cities or developing nations. The disease typically appears with an acute onset of monocular pain, redness, and perhaps a further decrease in vision. Examination reveals a severe IOP elevation, corneal edema, ciliary injection, open angles, and heavy cell and flare. The cells appear larger than white blood cells and somewhat iridescent. The cells may precipitate on the corneal endothelium, but no true keratic precipitates or hypopyon is seen. Ultrastructural analysis of aqueous humor and trabeculectomy specimens in phacolytic glaucoma have revealed melanin-laden macrophages, red blood cells (RBCs), ghost RBCs, macrophages showing erythrophagocytosis, and free cell debris in addition to the lens material-laden macrophages that are traditionally associated with this condition. The flare may be so heavy that the aqueous humor appears yellow. An important physical finding is the appearance of white particles on the anterior lens surface and in the aqueous; these particles are thought to be cellular aggregates or clumps of insoluble lens protein. Visual acuity is reduced in this condition, sometimes to the level of inaccurate light perception. The lens has a mature, hypermature, or even Morgagnian cataract ( Fig. 18-8 ). Rarely this disease is produced by an immature cataract with a zone of liquefied cortex.

Hypermature cataract.

On rare occasions, phacolytic glaucoma has a subacute course, with intermittent leakage of protein producing recurrent episodes of glaucoma, hyperemia, and inflammation. This appearance is more likely if the cataract has been dislocated into the vitreous. The diagnosis of phacolytic glaucoma is usually made on clinical grounds. If the diagnosis is in doubt, an anterior chamber paracentesis should be performed to detect macrophages engorged with lens material. Aqueous humor is examined by phase-contrast microscopy or Millipore filtration and staining.

Cataract extraction is the definitive treatment for phacolytic glaucoma. Before surgery, IOP and inflammation should be reduced by medical treatment, including hyperosmotic agents, topical adrenergic agents, CAIs, cycloplegic drugs, and topical corticosteroids. Traditionally most surgeons have removed these cataracts by an intracapsular technique. Microscopic examination of the lens reveals characteristic calcium oxalate crystals ( Figs 18-9 and 18-10 ). Because the lens capsule is quite fragile, a sector iridectomy and α-chymotrypsin are employed. If the capsule ruptures during delivery,the anterior chamber should be irrigated copiously to remove any residual protein. Other surgeons have used extracapsular cataract extraction in patients with this condition with good results. Because of the friability of the zonules and the brittleness of the capsule, the anterior capsulorrhexis may be performed by Vannas scissors or some other means that minimizes zonular and capsular stress. Lens delivery and residual cortical aspiration are also performed in an unusually delicate manner. In successful cases, posterior chamber IOL placement is possible and yields excellent results. As the last generation of surgeons trained in intracapsular surgery ages, the extracapsular technique will most likely replace the intracapsular approach. Regardless of approach, most patients have good visual acuity postoperatively and total remission of the glaucoma.

Calcium oxalate crystal in the lens of a patient with glaucoma associated with hypermature cataract. (Hematoxylin and eosin stain.)

In the same lens as Figure 18-9 , the calcium oxalate crystal is birefringent when viewed through polarized light.

If phacolytic glaucoma is caused by a dislocated lens, the lens should be removed by vitrectomy instruments. Occasionally a dislocated lens can be floated into the anterior chamber with a stream of irrigation fluid and then removed through a limbal incision.

In the rare situation when phacolytic glaucoma is caused by an immature cataract and the eye has good vision, attempts should be made to control IOP and inflammation by medical means. If this fails, the lens should be removed.

LENS-PARTICLE GLAUCOMA

Disruption of the lens capsule by penetrating trauma or surgery liberates lens material, which can obstruct the trabecular meshwork. The resulting glaucoma depends on the amount of lens material liberated, the inflammatory response of the eye, and the ability of the trabecular meshwork to clear the foreign matter. Generally the glaucoma has its onset a few days after the precipitating event. In rare cases, the lens material can be released long after surgery or trauma.

Patients with lens-particle glaucoma usually have significant pain, redness, and decreased vision. Examination reveals corneal edema, elevated IOP, open angles, heavy cell and flare, and chunky white particles in the aqueous humor. A hypopyon may be present, as may fluffy cortical material. If the condition has existed for some time, peripheral anterior synechiae and posterior synechiae may be present.

Generally the diagnosis of lens-particle glaucoma is suggested by the sequence of events. It is more difficult to diagnose delayed cases or cases with spontaneous rupture of the lens capsule, which may be confused with phacolytic glaucoma, phacoanaphylactic glaucoma, or other conditions. Anterior chamber paracentesis in this condition reveals macrophages and free lens material.

The elevated IOP and inflammation associated with lens-particle glaucoma are treated medically in the same fashion as phacolytic glaucoma. If this is not adequate, the residual lens material should be removed. Although fluffy cortical material can be aspirated easily, it is more difficult to remove solid lens material trapped in membranes behind the iris. Sometimes the entire lens mass can be teased from the eye after intracameral infusion of α-chymotrypsin. Lens particles in the vitreous can be removed with vitrectomy instruments. Surgery should not be delayed unduly in this disease or complications may occur, including posterior synechiae, peripheral anterior synechiae, cystoid macular edema, retinal detachment, and corneal decompensation.

PHACOANAPHYLAXIS

Phacoanaphylaxis is an uncommon condition that is thought to occur when patients become sensitized to their own lens protein. Phacoanaphylaxis typically develops after penetrating trauma or extracapsular cataract extraction. Histopathologically, these eyes have a granulomatous inflammation of the lens with polymorphonuclear leukocytes, lymphocytes, epithelioid cells, and giant cells. Occasionally the inflammation involves the trabecular meshwork and leads to a rise in IOP.

Phacoanaphylaxis is treated with medication to reduce inflammation and control IOP. If this is unsuccessful, residual lens material should be removed.

α-CHYMOTRYPSIN GLAUCOMA

α-Chymotrypsin fragments zonules and was used widely to facilitate intracapsular cataract extraction. However, elevated IOP often occurred within 1–5 days after using this drug. When examined, these eyes had open angles, decreased outflow facility, and increased IOP, which could be sufficient to cause corneal edema, wound disruption, and optic nerve damage. This entity is self-limited, lasting for 2–4 days and leaving no permanent abnormalities of aqueous humor dynamics.

The generally accepted mechanism for α-chymotrypsin glaucoma is that zonular fragments obstruct the outflow channels. This theory is supported by scanning electron microscopy, which shows zonular fragments in the trabecular meshwork, and by experimental studies in monkeys ( Fig. 18-11 ). A few investigators have proposed alternative mechanisms for the glaucoma, including inflammation or a direct toxic effect on the meshwork, but direct infusion of α-chymotrypsin into the anterior chamber of monkeys actually produced an increase in outflow facility. During the period of elevated IOP, patients are treated with topical and systemic glaucoma medications as needed. Patients with pre-existing optic nerve damage must be watched very closely because the pressure may rise to extremely high levels. The incidence and severity of the pressure rise can be reduced by using a lesser concentration of the drug (1:10 000 instead of 1:5000) in a lower volume (0.25–0.5 ml instead of 2 ml). The anterior chamber should be irrigated before lens extraction to remove zonular fragments. Prophylactic treatment with a variety of agents has generally failed to block this IOP rise, although one group found prophylactic timolol and acetazolamide useful in this situation. α-Chymotrypsin-associated IOP elevation is seen quite rarely today because intracapsular cataract extraction with α-chymotrypsin is rarely performed.

Scanning electron micrograph of the zonular fragments obstructing the trabecular meshwork after α-chymotrypsin administration.

Courtesy of Douglas Anderson, Miami.

GLAUCOMA FROM VISCOELASTIC SUBSTANCES

Viscoelastic substances often are employed in cataract surgery to protect the corneal endothelium and to facilitate intraocular lens (IOL) insertion. Sodium hyaluronate, the agent with perhaps the widest clinical use, frequently causes marked postoperative IOP elevations. When examined, these eyes demonstrate elevated IOP, deep anterior chambers, and corneal edema. Cellular and particulate matter in the aqueous humor may appear suspended and almost immobile if large amounts of viscoelastic remain in the anterior chamber, but IOP elevations may occur even in the absence of clinically detectable viscoelastic. It is sometimes possible to see tiny ruby-like globs of hemorrhage on the iris surface or suspended in the anterior chamber. These isolated blood droplets indicate the presence of retained viscoelastic. The IOP reaches a maximum in 12–16 hours and then abates spontaneously over the next 72 hours. During this period, patients are treated with topical and systemic glaucoma medications and hyperosmotic agents as needed to control IOP. The postoperative IOP rise can apparently be limited by removing as much of the sodium hyaluronate as possible at the end of the surgery, although some studies have failed to show a significant difference in IOP between eyes that have had the viscoelastic removed and those in which it was left in place at the end of surgery. Because it is difficult to standardize all of the variables that can affect the pressure rise in a given patient, it has been difficult to determine the effectiveness of various prophylactic treatment regimens on preventing the postoperative IOP rise seen after viscoelastic use. Some of these variables include the viscoelastic agent used, the surgeon, the surgical technique, the completeness of viscoelastic removal at the end of the procedure, and the rate at which the patient’s eye clears itself of retained viscoelastic.

It is postulated that viscoelastic substances obstruct the trabecular meshwork. This theory is supported by experiments showing that sodium hyaluronate causes elevated IOP in animal eyes and reduces outflow facility in enucleated human eyes. The latter is reversed by intracameral infusion of hyaluronidase. Hyaluronidase is normally present in the anterior segment of the eye but not in sufficient quantity to metabolize the large volume of sodium hyaluronate infused at surgery, at least in the short haul. Obstruction of the trabecular meshwork depends on more than the drug’s viscosity because low-viscosity sodium hyaluronate produces a greater rise in IOP in monkey eyes than does high-viscosity sodium hyaluronate.

Other viscoelastic substances have been evaluated for cataract surgery. Viscoat (a mixture of sodium hyaluronate and sodium chondroitin sulfate) produced similar IOP increases in one study, and marginally higher pressures in another. Chondroitin sulfate and methylcellulose may be less likely to elevate IOP.

GLAUCOMA WITH PIGMENT DISPERSION FROM INTRAOCULAR LENSES

Pigment dispersion and elevated IOP have been described with posterior chamber IOLs and, in a few cases, with iris fixation lenses. In most instances, the lenses have been decentered, tilted, excessively mobile, too small, or reversed in position, creating excess friction between the optic or haptic and the iris pigment epithelium. The pigment epithelial loss is geographic, and the iris may have a grey atrophic appearance. The pigment particles rubbed off the iris accumulate in the trabecular meshwork, where they obstruct aqueous humor outflow in a manner analogous to pigmentary glaucoma. Intraocular pressure rises days to months after cataract surgery but may improve spontaneously.

Patients with this entity are responsive to standard medical treatment for glaucoma and to ALT. In some cases, pupillary dilation or constriction may reduce the pigment dispersion. If IOP cannot be controlled, the IOL should be replaced or stabilized. This entity can be distinguished from pigmentary glaucoma by the temporal relation to cataract surgery, the unilateral state, and the absence of a typical Krukenberg’s spindle and radial transillumination defects.

UVEITIS-GLAUCOMA-HYPHEMA SYNDROME

The uveitis-glaucoma-hyphema (UGH) syndrome has been described with iris-supported, with posterior chamber, and most often with anterior chamber IOLs. The patients affected by this syndrome often have a history of uncomplicated cataract extraction but then develop elevated IOP, iridocyclitis, and recurrent hyphemas weeks to months after surgery ( Fig. 18-12 ). Ultrasonic biomicroscopy and aqueous humor analysis can aid in confirming the diagnosis. The patients may complain of recurrent episodes of extreme blurring (whiteout), presumably related to the hyphemas. The UGH syndrome is caused by excessive chafing of the iris by the pseudophakos because the lenses are too mobile, are poorly designed, or have poor finishing characteristics. Most of the lenses removed from these eyes show sharp or serrated edges capable of traumatizing iris tissue. Although some patients with a mild form of UGH syndrome respond to corticosteroid treatment and standard antiglaucoma therapy, in most cases the lens should be removed to prevent corneal decompensation and optic nerve damage. In a report of 101 IOLs explanted for a variety of reasons, patients with UGH syndrome had relatively poor visual outcomes, with 7 of 9 patients achieving a final visual acuity of less than 20/200. However, explantation did result in a decrease in pain and inflammation and better glaucoma control.

Uveitis-glaucoma-hyphema syndrome. (A) Inflamed eye of a patient following anterior chamber intraocular lens insertion. (B) Goniophotograph shows the footplate of the lens protruding posteriorly through the iridectomy and brushing against the ciliary processes.

GLAUCOMA AFTER NEODYMIUM:YTTRIUM-ALUMINUM-GARNET LASER POSTERIOR CAPSULOTOMY

Intraocular pressure often rises after neodymium:yttrium-aluminum-garnet (Nd:YAG) laser posterior capsulotomy and can reach levels of 60–80 mmHg. The IOP elevation usually occurs within 2–4 hours of the laser treatment and then abates spontaneously over the next 24 hours. However, in some patients, the pressure elevations can be delayed, can last for days to weeks, or can be severe enough to produce visual loss. Extreme IOP elevations are seen more often in eyes with pre-existing glaucoma and in eyes that do not have posterior chamber IOLs. There is some controversy about whether higher energy levels and larger capsulotomies are more likely to produce pressure rises, but most studies find little correlation. Intraocular pressure measurements should be taken 2–4 hours, 1 day, and 7 days after Nd:YAG laser capsulotomy. Pretreatment with apraclonidine 1% 1 hour prior to surgery and one drop 1 hour after surgery has been shown to decrease the number and severity of postoperative pressure spikes. The duration of the IOP rise may exceed the duration of action of the medication in some cases, and the pressure may be elevated the next day even after being measured as normal an hour or two after surgery. We generally give our patients an additional dose of apraclonidine to take just before bedtime on the night of surgery. This will theoretically help protect against a dangerous pressure rise in the very early morning hours. Patients who still have a substantial rise in IOP should be treated with a topical β-adrenergic antagonist, topical, or, if necessary, a systemic CAI, an α-adrenergic agonist, and hyperosmotic agents as needed to control IOP. Topical corticosteroids may be administered to reduce inflammation. There have been sporadic cases reported of Latanoprost-associated cystoid macular edema in pseudophakic eyes following posterior capsulotomy, but these are rare occurrences and the causal relationship remains obscure.

The pressure rise occurring after Nd:YAG laser capsulotomy is usually associated with particulate debris clogging the trabecular meshwork. Altamirano and co-workers used a flare-cell meter to prospectively measure the level of flare and the amount of particulate matter in the anterior chamber following Nd:YAG laser capsulotomy in 65 eyes of 58 patients. They found that the amount of particulate matter correlated strongly ( P <0.001) with postoperative pressure rises. The amount of flare also correlated with pressure rises, but not as strongly ( P <0.037). Others have found that following Nd:YAG laser capsulotomy in experimental animals, the aqueous humor contains fibrin, lens material, inflammatory cells, macrophages, and RBCs in sufficient quantity to obstruct the trabecular meshwork.

In a few patients, the vitreous moves forward and causes pupillary block. In other cases, Nd:YAG laser surgery causes sufficient bleeding or inflammation to obstruct outflow. More often, however, the outflow facility is reduced in the absence of severe inflammation or hemorrhage. Some have proposed that Nd:YAG laser surgery releases a dialyzable factor from the vitreous that blocks the outflow channels.

GLAUCOMA FROM VITREOUS IN THE ANTERIOR CHAMBER

Vitreous in the anterior chamber is a rare cause of open-angle glaucoma in aphakic eyes. The glaucoma usually begins within weeks after cataract surgery but may be delayed for months. In most cases, the vitreous reaches the anterior chamber after a spontaneous rupture of the hyaloid face or after an extensive posterior vitreous detachment. In a few cases, vitreous is left in the anterior chamber at the time of cataract extraction. When examined, these eyes demonstrate elevated IOP and open angles. Vitreous fills the anterior chamber and appears to be in contact with the trabecular meshwork. It should be emphasized that in many cases, confirming this contact by clinical examination is impossible.

The mechanism of the glaucoma in this entity is not clear because vitreous is present in the anterior chamber of many aphakic eyes without causing problems. It is postulated that glaucoma occurs when a large bolus of vitreous comes into contact with a major portion of the trabecular meshwork and obstructs the outflow system. Grant infused vitreous into enucleated human eyes and found a diminished outflow facility that was reversed by hyaluronidase. In some cases, the mechanism of the glaucoma is more complicated and includes inflammation, pupillary block, and the formation of peripheral anterior synechiae.

Glaucoma caused by vitreous in the anterior chamber is usually a self-limited condition. The vitreous often retracts with time, and then IOP decreases. During this period, topical and systemic pressure-lowering medications are employed to control IOP. The response to miotics is unpredictable in this condition, with some patients helped and others not. Many patients respond better to cycloplegic drugs than to miotics. In unresponsive patients in whom the optic nerve is threatened, vitrectomy should be considered.

CHEMICAL BURNS

Chemical burns are often associated with a complex pattern of IOP alterations that include an immediate IOP rise followed by a period of hypotony, which in turn is followed by an elevation in the intermediate or late phases of the disease process. Glaucoma is more common after alkali burns but can also be seen after severe acid burns. The diagnosis of glaucoma is often difficult in patients with chemical injuries because opacities of the media may interfere with optic nerve and visual field assessment. Also, external swelling, scarring, and corneal irregularity may interfere with standard methods of tonometry. Intraocular pressure measurements may be more accurate with the pneumatic or MacKay-Marg tonometers than with the Goldmann applanation tonometer.

Intraocular pressure elevations in the early phase of disease are caused by scleral shrinkage and release of active substances, including prostaglandins. This situation is managed by topical and systemic medications, including β-adrenergic antagonists, α-adrenergic agonists, CAIs, and hyperosmotic agents as needed.

Elevated IOP in the intermediate phase is usually caused by inflammation. These eyes are treated with aqueous suppressants, hyperosmotic agents, and cycloplegic drugs. Topical and systemic corticosteroids are also used, but the patients must be monitored closely to avoid corneal melting. At times, sufficient posterior synechiae form to produce pupillary block, which requires vigorous pupillary dilation and/or iridectomy. Acute lens swelling can also produce pupillary block.

Late elevations of IOP are usually caused by trabecular damage and formation of peripheral anterior synechiae or other intraocular scarring. This situation is usually managed by standard medical therapy. Filtering surgery may be required but can be technically difficult if there is extensive scarring of the conjunctiva and episcleral tissues. If extensive scarring is present, a cyclodestructive procedure or a glaucoma drainage device procedure such as an Ahmed or Molteno valve should be considered.

ELECTRIC SHOCK

Transient IOP elevations have been reported after electric injury, cardioversion, and electroshock therapy. Various investigators have attributed the pressure rise to venous dilation, contraction of the extraocular muscles, and pigment dispersion. Because the IOP elevation is usually transient, no therapy is administered.

RADIATION

Radiation can cause elevated IOP through a variety of mechanisms, including neovascularization, open-angle glaucoma associated with diffuse conjunctival telangiectasia, and ghost-cell glaucoma associated with radiation retinopathy and vitreous hemorrhage. In many cases, the widespread ocular disease and radiation damage indicate a poor prognosis.

PENETRATING INJURIES

Penetrating injuries can produce elevated IOP through various mechanisms, including flat anterior chamber with formation of peripheral anterior synechiae; inflammation, including sympathetic ophthalmia; intraocular hemorrhage, including hyphema and ghost-cell glaucoma; lens swelling with pupillary block; lens subluxation with pupillary block; lens-particle glaucoma; phacoanaphylaxis; posterior synechiae with pupillary block; epithelial downgrowth, and fibrous ingrowth. When penetrating trauma includes retained organic material, severe inflammation and secondary glaucoma often follow. When blunt and penetrating trauma are combined, angle recession or other forms of direct trabecular damage may produce elevated IOP.

Retained metallic foreign bodies can produce open-angle glaucoma months to years after the injury. It is postulated that iron released from the foreign body is toxic to several ocular tissues, including the retina and the trabecular meshwork. This condition, known as siderosis , is similar to hemosiderosis, which results from the release of iron from blood. When examined, eyes with siderosis demonstrate heterochromia, mydriasis, elevated IOP, decreased outflow facility, and a diminished electroretinogram. The deep cornea, trabecular meshwork, and anterior subcapsular region of the lens all have a rust-brown color. In some eyes, a previous corneal scar and an iris transillumination defect indicate the path of injury.

Prevention is the key to treating ocular siderosis. Traumatized eyes must be examined carefully with indirect ophthalmoscopy, gonioscopy, ultrasound, radiography, and computed tomography (CT) studies to detect metallic foreign bodies. Whenever possible, the foreign bodies should be removed to prevent this occurrence. Once glaucoma is present, the foreign body may be so encapsulated that standard extraction techniques may not be possible. Furthermore, at this stage, the prognosis may be limited by extensive retinal damage. Standard medical and surgical means are used to treat the glaucoma. Glaucoma and retinal changes are also seen in chalcosis, which is caused by copper-containing foreign bodies.

CONTUSION INJURIES

Contusion injuries occur most frequently in young men and can cause hyphema, iridocyclitis, iris sphincter tears, iridodialysis, cyclodialysis, lens subluxation, retinal tear or dialysis, retinal detachment, vitreous hemorrhage, choroidal rupture, and glaucoma. Postcontusion glaucoma can occur immediately after the injury or be delayed for months to years. Uveal effusion and angle closure can occur rarely after blunt trauma.

The pressure rise that occurs immediately after non-penetrating trauma can be severe but is usually limited in duration to days or weeks. During this period, patients are treated with topical β-adrenergic antagonists, CAIs, and hyperosmotic agents as needed to control IOP. The cause of the early pressure elevation is often complex and includes trauma to the trabecular meshwork as well as obstruction of the outflow channels by RBCs, leukocytes, pigment, and inflammatory debris. Tears in the trabecular meshwork typically occur after contusions but often are not recognized because gonioscopy is not performed routinely ( Fig. 18-13 ). The tears have the appearance of a hinged flap, with the cut edge posterior to Schwalbe’s line. The tear in the meshwork heals within several weeks to months, leaving an area of scarring that is sometimes combined with peripheral anterior synechiae.

Drawing of an acute flap tear in the trabecular meshwork following ocular trauma.

In some cases, IOP is low after trauma and then becomes elevated weeks to months later. The likely explanation for this phenomenon is that both outflow facility and aqueous production are reduced immediately after trauma, and then aqueous production recovers first. An alternative explanation is the closing of a tear in the trabecular meshwork or a traumatic cyclodialysis cleft. The IOP elevation that occurs during this period can be very severe and may require filtering surgery if medical treatment fails.

Glaucoma can also occur years or even decades after blunt trauma. Most patients with postcontusion glaucoma have unilateral increased IOP, decreased outflow facility, open angles, and quiet eyes. Many patients have no memory of ocular trauma, whereas others only recall the injury after being questioned by a physician. Other patients will deny a specific history of ocular trauma but fail to consider a routine sports-related injury such as that which occurs during boxing matches or other similar activities. The key finding is a previous tear in the ciliary muscle, called an angle recession ( Fig. 18-14 ). This may be present in the entire circumference of the angle or only in scattered areas. The recession is usually recognized gonioscopically as an irregular widening of the ciliary band. At times, the angle recession is very subtle. In these cases, it is only diagnosed by comparing one eye with the fellow eye or one part of the angle with the remaining parts. Other clues of angle recession include absent or torn iris processes, posterior attachment of the iris root ( Fig. 18-15 ), an anterior chamber deeper than in the fellow eye, and increased visibility and width of the scleral spur. Late glaucoma is more frequent if the recession involves three-quarters or more of the angle but can occur even with recessions of 1 clock hour or less. The angle recession is not the cause of the glaucoma, but rather it is an indicator of previous trauma. Late glaucoma occurs in an estimated 2–10% of eyes after contusion injuries.

(A) Goniophotograph of a recessed angle. The angle recess and the width of the ciliary body band vary from area to area. (B) Blood in the angle following traumatic angle recession. Jugular compression resulted in discharge of blood from Schlemm’s canal into the anterior chamber in this patient who suffered angle recession some months previously. The patient had experienced periodic blurring of vision with pressure elevation as a result of this blood in the anterior chamber. It was resolved with laser applied to the bleeding point.

From Campbell DG, Netland PN: Stereo atlas of glaucoma, St Louis, Mosby, 1998.

Histopathology of a previous tear into the ciliary face showing the root of the iris recessed posterior to Schlemm’s canal.

It is thought that eyes with an underlying tendency to develop open-angle glaucoma are more likely to develop late increased IOP after blunt trauma. This theory is supported by the observation that many of the supposedly normal, untraumatized fellow eyes have spontaneous IOP elevations. Furthermore, the normal fellow eyes respond to topical corticosteroids, similar to eyes with POAG.

The unifying theory is that eyes with marginal outflow facility are more likely to develop pathologic pressure elevations with trabecular injury than are eyes with excess or reserve outflow facility. Because the outflow facility tends to be about equal in the two eyes, a patient with angle recession and glaucoma might well be expected to have poor outflow in the fellow eye.

Histopathologic study of eyes with post-traumatic glaucoma may reveal a cuticular membrane covering the trabecular meshwork. However, it is not clear whether this membrane is the cause of the glaucoma.

The treatment of late postcontusion glaucoma usually consists of the full antiglaucoma regimen, including miotics. Argon laser trabeculoplasty is often disappointing in this condition but should be considered before proceeding to filtering surgery. It should be emphasized again that the untraumatized fellow eyes should be watched closely for elevated IOP.

GHOST-CELL GLAUCOMA

Ghost-cell glaucoma is an uncommon condition that occurs in association with intraocular hemorrhage. In this entity, RBCs degenerate in the vitreous, migrate forward to the anterior chamber through a disrupted anterior hyaloid face, and then obstruct the trabecular meshwork. The vitreous hemorrhage is usually caused by retinal disease, trauma, or surgery; a recent case report associated ghost-cell glaucoma with snake poisoning injury. Generally the anterior hyaloid face has been disrupted by vitrectomy, cataract surgery, or trauma, but ghost-cell glaucoma has been reported in non-traumatized phakic eyes as well. The RBCs in the vitreous degenerate to tan-colored spheres (ghost cells), which appear empty except for clumps of denatured hemoglobin called Heinz bodies. The ghost cells are more rigid than are normal RBCs and thus are less able to pass through the trabecular meshwork. This proposed mechanism is supported by animal experiments in which infusion of fixed RBCs produced elevated IOP.

When examined, patients with ghost-cell glaucoma have elevated IOP, which may be sufficient to cause pain and corneal edema. Slit-lamp examination shows tiny, tan-colored cells in the vitreous, aqueous, and trabecular meshwork. Sometimes the cells in the anterior chamber are so numerous that they settle into a pseudohypopyon. The diagnosis of ghost-cell glaucoma is confirmed by anterior chamber paracentesis. The anterior chamber aspirates can be passed through a Millipore filter and then stained, or the fluid can be examined by phase-contrast microscopy.

Ghost-cell glaucoma is a transient condition that can last for weeks or months depending on the volume of blood in the vitreous and the ability of the trabecular meshwork to clear the degenerated cells. Many cases are controlled by standard medical therapy, including topical β-adrenergic antagonists, α agonists, topical CAIs (oral if necessary), and hyperosmotic agents. Resistant cases are treated with anterior chamber washouts, which can be repeated as needed. If IOP cannot be controlled by repeated anterior chamber lavage, a vitrectomy should be performed to remove as much of the blood as possible.

HEMOLYTIC GLAUCOMA

Hemolytic glaucoma is a rare form of glaucoma associated with intraocular hemorrhage. It resembles ghost-cell glaucoma, except that in hemolytic glaucoma macrophages phagocytize RBC debris and then occlude the trabecular meshwork. When examined, these eyes demonstrate elevated IOP, reddish cells in the aqueous humor, open angles, and increased pigmentation of the trabecular meshwork. The diagnosis is confirmed by anterior chamber paracentesis, which reveals pigment-containing macrophages rather than khaki-colored ghost cells. Microscopic study of eyes with hemolytic glaucoma shows the trabecular meshwork to be occluded by RBCs, debris, and macrophages laden with pigment. Hemolytic glaucoma is usually a self-limited condition that responds to management with topical and systemic pressure-lowering medications. If IOP is not controlled, an anterior chamber washout should be performed. If this is not successful, a filtration or cyclodestructive procedure may be indicated.

HEMOSIDEROSIS

Hemosiderotic glaucoma is a rare entity associated with intraocular hemorrhage. Hemosiderosis is similar to siderosis, except that the source of iron in hemosiderosis is degenerating RBCs rather than a retained foreign body. Hemoglobin released by degenerated RBCs is phagocytized by trabecular endothelial cells. The iron liberated from the hemoglobin causes siderosis and discoloration of the meshwork.

HYPHEMA

Blunt trauma to the globe can produce a tear in the ciliary face and bleeding into the anterior chamber. Traumatic hyphemas can occur in patients of any age or either gender but are typically seen in young men. Patients with hyphemas complain of redness and blurred vision; if IOP is elevated, patients may also complain of pain, nausea, and vomiting. The history of the injury reveals trauma that seems severe in some cases and trivial in others. In all cases, however, the object causing the trauma must have been small enough or sufficiently deformable to fit inside the rim of the orbit in order to strike the globe.

When examined, patients with hyphemas demonstrate diminished vision, conjunctival injection, RBCs floating in the aqueous humor, a variable amount of blood settled to the bottom of the anterior chamber, and normal or low IOPs. Children with traumatic hyphemas often appear somnolent. In most patients, the blood clears spontaneously in a few days with no immediate complications. A few weeks after the injury, these patients should have a careful dilated examination to search for retinal tears, retinal dialyses, and choroidal ruptures. They should also undergo gonioscopy to determine whether angle recession is present.

Unfortunately some patients with traumatic hyphemas have recurrent episodes of hemorrhage into the anterior chamber, or re-bleeds. Most episodes of re-bleeding occur within a few days of the trauma. It is postulated that additional bleeding occurs when the blood clot closing the vessel torn in the original injury undergoes lysis and retraction. Reports indicate that re-bleeding after traumatic hyphema occurs in 4–35% of patients. There is reasonable evidence linking aspirin use to re-bleeding. Some authorities also believe that re-bleeding is more common in blacks and in individuals with larger hyphemas and hypotony.

Re-bleeding is important because it is often associated with complications, including corneal blood staining ( Fig. 18-16 ), optic atrophy, and elevated IOP. In most cases, elevated IOP is caused by RBCs obstructing the trabecular meshwork. Less often, the blood clot may produce pupillary block. Glaucoma is more frequent when the hyphema is total. A total hyphema changing color from red to black ( black-ball or eightball hyphema ) is an ominous sign of impending complications. The exact reason for this is obscure, but it is assumed that the underlying injury is more severe in many eyes with eightball hyphema compared with eyes with subtotal hyphema.

Blood staining of a cornea that is beginning to clear in the periphery.

The management of traumatic hyphema has been controversial. Typical practice in the past was to hospitalize all patients for bed rest, sedation, and bilateral patching. However, there is evidence that bed rest and patching are not necessary and that equally good results can be obtained by limiting activity. If there is a stable family situation, some patients can be managed at home and checked daily in the physician’s office. Despite widespread use, no evidence suggests that either cycloplegics or miotics facilitate the clearing of blood. The antifibrinolytic agents epsilon-aminocaproic acid (Amicar) and tranexamic acid have been found to decrease the incidence of rebleeding. The reported track record of tranexamic acid remains fairly good, although its use is not entirely without risk. The effectiveness of aminocaproic acid has been questioned by some investigators, who found no significant difference in re-bleed rates between patients treated with aminocaproic acid and those treated with either corticosteroids or placebo.

This has been a difficult issue to study. The re-bleed rate of the control groups in these studies ranges from less than 5% to over 25%. In several cases, the patients in the study group were collected over periods of 10 years or more, and it is difficult to be certain that identical diagnostic criteria and treatment regimens were employed. For the most part, the studies with high rates of re-bleeding in the control group found the medications helpful. Other studies with seemingly similar entry criteria and treatment plans had low re-bleed rates in the control group and showed no benefit from aminocaproic acid. Some authorities recommend that all patients with traumatic hyphemas be treated with an antifibrinolytic agent, assuming no contraindication. Other authorities use these agents only after severe trauma or in patients with large initial hyphemas. The best available data support using these agents in circumstances in which the re-bleed rate is likely to exceed about 10%. If this is the case in the experience of a particular hospital or practice, it would also seem prudent to carefully review the entire treatment regimen as well as the circumstances and extent of the injury causing the hyphema and the support services available to the patient during convalescence. A few reports indicate that systemic corticosteroids reduce the rate of rebleeding, although this was not confirmed in other studies. Again, patient demographics, the circumstances of injury, and other critical factors are difficult to compare. Elevated IOP associated with a traumatic hyphema is managed by topical and systemic glaucoma medications as needed. Topical corticosteroids are administered if the eye is significantly inflamed, independent of any potential positive effect on re-bleeding rates.

Non-clearing total or subtotal hyphema is a serious condition. In addition to other damage to the eye caused by the event that produced the hyphema, the hyphema itself can cause corneal blood staining, persistent inflammation, and dramatically elevated IOP. Tissue plasminogen activator (t-PA) is a fibrin-specific fibrinolytic agent that has shown promise in experimental and limited clinical use. Current experience remains limited, at least partially because appropriate cases are rare. Early case reports have been favorable, however.

Surgical removal of blood from the anterior chamber is indicated for persistent pain, corneal blood staining, or IOP elevations threatening the optic nerve. It is difficult to know what IOP level will be tolerated by young healthy patients who have no pre-existing optic nerve disease. One proposed guideline is that an IOP of 60 mmHg for 2 days, 50 mmHg for 5 days, or 35 mmHg for 7 days requires intervention. If possible, evacuation of blood should be delayed until the fourth day because, at this time, the clot is somewhat retracted and less adherent to the surrounding tissues. Sometimes, a simple paracentesis allows the clot to retract enough from the chamber angle to allow drainage to occur. Removal of blood also can be done as a washout through a peripheral corneal puncture using saline or a fibrinolytic agent such as urokinase, fibrinolysin, or, when available, t-PA. Liquid blood is irrigated from the eye during this maneuver; it is neither necessary nor wise to remove the entire clot. If the anterior chamber remains shallow and a large clot persists, the surgeon may consider performing an iridectomy to relieve pupillary block.

Some surgeons recommend treating the hyphema through a larger limbal incision using manual expression, ultrasonic emulsification, cryoextraction, or vitrectomy instruments. Other experts recommend a trabeculectomy procedure with or without evacuation.

Patients with sickle cell trait are at great risk of developing IOP elevations and optic nerve damage after traumatic hyphemas. The abnormal RBCs in the anterior chamber develop sickle deformity so they are less able to pass through the trabecular meshwork. Furthermore, increased IOP may reduce the perfusion pressure to the optic nerve and retina and lead to sickling of RBCs within the vessels of these tissues. Accordingly, more aggressive treatment is indicated in patients with sickle cell trait. Unfortunately patients with sickle cell trait may respond adversely to a variety of medications, including hyperosmotic agents, adrenaline (epinephrine), and acetazolamide. However, these individuals generally tolerate topical β-adrenergic antagonists and methazolamide. It has been suggested that mean IOPs greater than 25 mmHg or pressure spikes higher than 30 mmHg indicate the need for surgery in patients with sickle cell trait and traumatic hyphema. One report states that hyperbaric oxygen reduces sickling of RBCs in the anterior chamber of rabbits.

Not all hyphemas arise from contusion injuries. Intraocular bleeding can also occur with penetrating trauma, surgery, neovascularization of the iris or a previous wound, IOLs, tumors, or vascular tufts at the pupillary margin. Elevated IOP is managed with medical therapy and with washout if necessary.

SCHWARTZ SYNDROME

In a minority of cases, retinal detachment causes a peculiar increase in IOP that is referred to as Schwartz syndrome . In this syndrome, rhegmatogenous retinal detachment is associated with elevated IOP, diminished outflow facility, open angles, and cell and flare in the aqueous humor. When the retinal detachment is repaired, theIOP and outflow facility return to normal. It has been postulated that the glaucoma is related to angle recession, inflammation, pigment granules released by the retinal pigment epithelium, and glycosaminoglycans synthesized by the photoreceptors. 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.