Cataracts and Glaucoma
MARC ELLMAN and JEFFREY S. SCHULTZ
Table Of Contents
CATARACTS AND CONGENITAL GLAUCOMA|
ANTERIOR SEGMENT ANOMALIES (IRIDOCORNEAL DYSGENESIS)
GLAUCOMA SECONDARY TO CONGENITAL CATARACT SURGERY
CATARACTS AND PRIMARY ANGLE-CLOSURE GLAUCOMA
ANGLE-CLOSURE GLAUCOMA CAUSED BY PUPILLARY BLOCK
CATARACTS AND OPEN-ANGLE GLAUCOMA
GLAUCOMA MEDICAL THERAPY
CATARACTS AND SECONDARY GLAUCOMA
|Cataracts and glaucoma have common factors linking their development and
progression. Both occur with greater prevalence with advancing age, and
there may be a causal relationship between the two in some cases. In
an attempt to clarify these two common ocular diseases, which are usually
noted as being the second and third leading causes of visual impairment
in the United States, a simple classification based on the types
of glaucoma and associated cataracts is suggested. Both naturally
occurring and iatrogenic factors under each classification can be defined, and
it is hoped that this allows a rational approach to the management
of the individual glaucoma patient with cataracts.|
Hippocrates made no distinction between cataracts and glaucoma. According to the Greek writings, the term glaucoma defines a “glazed appearance without luster.” In the translation from Greek to Latin, and subsequently into Arabic, this disorder was termed “suffusio.” In the translation of the Arabic teachings back to Latin during the Middle Ages, the term cataract, meaning “waterfall,” was used in reference to suffusio. The term cataract was not known to the Greek writers. Subsequently, the distinctions between the two distinct diseases were first made and accepted during the 17th and 18th centuries. Since that time, they have been treated and approached as two separate but not mutually exclusive causes of human visual impairment.
|CATARACTS AND CONGENITAL GLAUCOMA|
In infantile glaucoma (without other associated anomalies) there have been notations of cataracts before the patients underwent glaucoma surgery. However, in the majority of patients with infantile glaucoma without anomalies, there are no associated congenital cataracts. When lens opacities do occur, they typically occur after surgical intervention, including both angle and filtering surgery. During the surgery for resistant infantile glaucoma, if fistulizing procedures are necessary, occasionally the crystalline lens is lax and may have a tendency to dislocate; this accounts for the prolapse of the lens into the anterior chamber and the fistula that results in cataractous changes.
Another association of the lens with infantile glaucoma is microphakia. However, this may be a misnomer because of the buphthalmic enlargement of the globe.3 Fortunately, overall, uncomplicated infantile glaucoma without congenital or secondary cataracts is encountered most commonly.
Performing lensectomy during the first 4 weeks of life is associated with a higher risk of subsequent glaucoma than when surgery is performed at a later date. The reason for this association is unknown, but it seems reasonable to delay surgery until the infant is more than 1 month old. These children must undergo regular screenings for glaucoma because it can develop at any time.4 A conflicting report suggests that early cataract surgery (within the first 2 weeks of life) is associated with the fewest postoperative complications, including glaucoma, nystagmus, strabismus, and secondary membranes.5
|Aniridia is a rare congenital disorder characterized by bilateral iris
hypoplasia. The incidence ranges from 1:64,000 to 1:96,000.6Aniridia has been associated with glaucoma, cataracts, corneal opacities, foveal
hypoplasia, optic nerve hypoplasia, and nystagmus.7 The term aniridia, signifying an absence of the iris, is a misnomer. In
most, if not all cases of aniridia, a stump of tissue is present at
the base of the iris.8 Six percent to seventy-five percent of patients with aniridia develop
glaucoma, usually during late childhood or adolescence.6 The development of glaucoma results from progressive changes in the anterior
chamber angle occurring during the first two decades of life.7 Although the angle was felt by many to be maldeveloped, glaucoma is most
likely caused by a progressive mechanical rolling up of the iris stump (Fig. 1).9 Recently it has been discovered that patients with congenital aniridia
have significantly increased central corneal thickness (average
of 631.6 µm), thus potentially leading to inaccurate measurements
of intraocular pressures.10 Unfortunately, aniridic glaucoma seems to be refractory to both medical
and surgical treatments. Swanner and co-workers have proposed performing
prophylactic goniosurgery in select aniridic eyes with early progressive
angle changes, and have achieved encouraging results.7|
Cataracts may be present in a large number of aniridic patients, appearing with advancing age. They are most often developmental and are cortical or polar in location. Cataracts also may be present at birth owing to subluxed or dislocated lenses with adherence to the cornea endothelium. Any surgical procedures performed for aniridia, such as goniotomy for lysis of iris stump adhesions or filtration procedures, also may hasten or cause the development of cataracts. If a child's vision is threatened, cataract formation in aniridia must be treated surgically in an effort to prevent amblyopia. Membranous cataracts and glaucoma formation also have been reported with aniridia.9
|ANTERIOR SEGMENT ANOMALIES (IRIDOCORNEAL DYSGENESIS)|
|Congenital glaucoma can be seen in virtually the entire spectrum of anterior
segment anomalies. |
Axenfeld-Rieger syndrome commonly is associated with glaucoma and occasionally with cataracts as well. It is characterized by posterior embryotoxon (anterior displacement of Schwalbe's line) combined with other ocular findings, such as attached iris strands, iris hypoplasia, and anterior chamber dysgenesis. Fifty percent of these eyes develop glaucoma in late childhood or adulthood.11 Cataracts also are occasionally found in these patients, although not as commonly as glaucoma. When present, lenticular changes vary from nuclear cataracts to anterior polar cataracts. Coloboma of the lens and ectopia lentis also may be present. The glaucoma usually develops before any significant cataract formation in the second or third decade of life. Of note, posterior embryotoxon can be seen as an isolated finding in 15% of normal patients.
Peter's anomaly consists of a posterior corneal defect with opacity of the stroma. In some cases, iris strands adhere to the border of the corneal defect and in severe cases the lens itself adheres to the corneal defect. Peter's anomaly is often the final result of defects such as congenital rubella and the Axenfeld-Rieger's syndrome.11 Peter's anomaly is the most severe of the spectrum of mesodermal dysgeneses, representing difficulties with cataracts and glaucoma often occurring at birth. Because of the severity of the problem, early cataract extraction may be necessary, possibly combined with corneal transplantation. In some instances, only corneal surgery is needed. Goniotomies are difficult to perform in these patients and may be of no benefit. Often the associated glaucoma has to be treated essentially as open-angle glaucoma; fistulizing operations may be necessary. Trabeculotomy for this condition has been associated with secondary cataracts.11
Marfan's syndrome is an entity involving the musculoskeletal, cardiovascular, and ocular tissues. Ectopia lentis is seen in up to 70% of those afflicted. The lens also may be globular and have small cortical opacities. Glaucoma can be seen in up to 75% of people with Marfan's syndrome, and often is congenital with anterior chamber anomalies. However, the glaucoma also can be caused by the forward dislocation of the anomalous lens, resulting in secondary angle-closure glaucoma. Miotics have been known to increase pupillary block with such lenses, giving a “paradoxic” angle closure. Treatment may be directed to mydriasis or peripheral iridectomy for this secondary angle-closure glaucoma. If the glaucoma is on the basis of angle anomalies, goniotomies have been attempted. Removal of the lens often results in vitreous loss and should be done only in a vision-threatening situation. Also, any time surgery is performed in a patient with Marfan's syndrome, thromboembolic phenomena associated with anesthesia should be addressed as possible complications.
Weill-Marchesani's syndrome can be associated with microspherophakia, lens subluxation, and angle anomaly associated with mesodermal dysgenesis.12 Congenital glaucoma can occur from the angle dysgenesis or a lens dislocation can give rise to a secondary angle closure. Although no reports of cataracts primarily occurring in this syndrome have been described, cataract formation can occur. Capsular tension rings may be a useful adjunct to cataract surgery in these and similar patients.13
The oculocerebrorenal syndrome known as Lowe's syndrome was first described in 1952.14 It is one of the two major syndromes with naturally occurring cataracts and congenital glaucoma (the other is rubella). The cataracts are bilateral and occur in virtually all reported cases.3 They are present prior to the fifth week of development in utero, with defects of the anterior, equatorial, and posterior subcapsular areas. This is a sex-linked inherited disease. Female carriers exhibit punctate opacities of the lens, which do not cause visual impairment (Fig. 2). Glaucoma, which is present in 60% to 70% of patients, is of an infantile variety with angle anomalies. Systemic manifestations include mental retardation and renal anomalies resulting in aminoaciduria.
Ocular treatment usually is directed toward prevention of amblyopia by aspiration of cataracts and includes goniotomy for the glaucoma. It may be best to do the glaucoma surgery first, followed by lens aspiration. These eyes often respond poorly, with secondary hemorrhages resulting from goniotomies and, despite intensive therapy, blindness may result. Because of the systemic defects, including mental retardation and bone abnormalities resulting from secondary rickets, the overall prognosis is poor.
The other major common syndrome in which infantile glaucoma is associated with congenital cataracts is rubella, also known as German measles. This is classified as a syndrome and is caused by an in utero rubella virus infection.3
In patients in whom the virus infection occurs during the first trimester of pregnancy, cataracts and glaucoma may both develop. If the infection occurs later, such as during the second trimester, only the glaucoma ensues, because by this time the lens has completed its embryonic capsular development. The glaucoma is frequently attributed to angle maldevelopment. Glaucoma occurs in 10% to 20% of those with rubella, whereas cataracts develop 10 times more frequently. The two may be mutually exclusive in some cases.
Heart anomalies, mental retardation, and hearing abnormalities are associated along with the ocular problems. These have to be considered in determining the time of surgical intervention. The cataracts are usually nuclear in location, but the cortical fibers often become involved secondarily. There have been reports of persistence of the virus in the lens, and this should be considered when performing aspiration of the lens in the infant.3 Spherophakia has been noted histologically and could conceivably result in pupillary block in rare instances. Continued development of the angle after birth could account for some of the reported cases of spontaneous resolution of the infantile glaucoma. An interesting observation of specks or pigmentation of the angle has been described in infantile glaucoma.15 This is in addition to the typical mottled pigmentation of the retinal posterior pole. A concomitant keratitis may complicate the picture when one is attempting to make a determination as to whether the pressure is elevated in infancy. This keratouveitis may rarely cause a secondary form of glaucoma. When cataracts and glaucoma occur together, the glaucoma usually should be treated before the cataract surgery.16 Secondary glaucoma can occur after cataract surgery. Despite modern surgical techniques, visual acuity after cataract extraction still remains poor in many of these patients.17
Homocystinuria is caused by an autosomal recessive enzymatic defect, resulting in increased blood concentrations of homocysteine and methionine. Inability to metabolize homocystine is apparently caused by the absence of cystathionine beta-synthase.18 Aminoaciduria, mental retardation, a fair appearance, malar flush, and a stature similar to Marfan's syndrome are possible systemic findings. The ocular findings include dislocated lenses in 90% of patients and often a pupillary block with secondary glaucoma.19 Cataracts are seen in 20% of patients, and glaucoma on a secondary or congenital basis is seen in approximately 10% of patients. A nonsurgical treatment consisting of a low methionine diet and supplementary vitamin B6 during the early weeks of infant life has been shown to significantly reduce the risk of ocular complications associated with this disease.19,20 Any surgical treatment must take into account the tendency for thromboembolic phenomena under general anesthesia in those with this disease.
Many chromosomal anomalies have been associated with ophthalmic disorders, including cataracts and glaucoma. These and other eye findings usually are seen together with other systemic signs such as deafness, heart defects, mental retardation, polydactyly, seizures, and cleft lip. Three of the more common chromosomal anomalies are trisomy 21, 18, and 13 (Down's, Edward's and Patau's syndromes, respectively), which all can have ophthalmic manifestations.
Trisomy 21 affects approximately 1.69 in 1000 live births, making it the most common major chromosomal abnormality.21 Ophthalmic disorders are encountered in 60% of these patients, with congenital cataracts seen in approximately 3%, according to one source.22 A majority of Down's syndrome patients have acquired lens opacities by adulthood as a complication of the premature senescence commonly seen.23
Trisomy 18 and 13 occur at much lower incidences than trisomy 21. Both have poor 1-year survival rates and only rarely do patients live into their teen years. Patients with these two disorders often suffer from a variety of physical developmental problems, including microphthalmia. If the microphthalmia is severe enough, it can lead to primarily nuclear cataract formation and persistent hyperplastic primary vitreous (PHPV), the latter sometimes associated with glaucoma. Surgical intervention for cataracts and glaucoma must be weighed in view of the overall poor prognosis of these and the many other chromosomal syndromes.24
PIERRE ROBIN'S SYNDROME
This syndrome of micrognathia, cleft palate, and glossoptosis has varied ocular anomalies, including congenital glaucoma and cataracts.25 Retinal detachment, high myopia, microphthalmia, and esotropia also are noted. Failure of the lower jaw to come forward with normal development at approximately the fourth month of fetal life could be associated with concomitant angle anomalies, resulting in angle maldevelopment at the same stage of embryogenesis. The cataracts consist of posterior subcapsular opacities. The glaucoma may require surgical intervention. When surgery is necessary, any heart defects must be considered when assessing risk. The prognosis is not poor, however, and attempts to prevent visual deprivation or blindness often are rewarding.
PERSISTENT HYPERPLASTIC PRIMARY VITREOUS
Persistent hyperplastic primary vitreous is a congenital anomaly in which the primary vitreous adheres to the posterior capsule of the lens, resulting in cataract formation. Glaucoma is not on the basis of angle anomalies, but usually is secondary to angle closure, because of either intumescence of the lens or hemorrhage from the persistent vessels on the posterior aspect of the lens. The glaucoma usually is approached as a secondary angle-closure glaucoma, with iridectomy or lens aspiration as the treatment of choice.
Retinopathy of Prematurity
In advanced retinopathy of prematurity, tissue from the retinal periphery can extend to the retrolental area, and this fibrovascular tissue can form a pseudotumor. As this progresses, total retinal detachment, secondary hemorrhage, swelling and edema of the mass, and the development of posterior synechia can occur. The anterior chamber can become shallow, resulting in secondary angle-closure glaucoma. This has been noted to occur in approximately 2% of patients. Lens aspiration may be performed to relieve the forward displacement of the iris-lens diaphragm (Fig. 3), and iridectomy usually is necessary. This is often done for cosmetic purposes to prevent enucleation, as vision is usually poor because of the underlying retinal problems.
Angle-closure glaucoma after photocoagulation for retinopathy of prematurity has been reported.26 Confluent laser photoablation also has been associated with cataracts and other complications,27 mostly related to anterior chamber ischemia.28 Overall, the incidence of cataract formation in patients who have undergone argon laser photocoagulation for retinopathy of prematurity is approximately 1%. The occurrence of cataracts may be higher when persistent hyaloidal vessels are present on the lens.26
For a complete list of all the associated syndromes of lenticular opacities with infantile glaucoma, several other syndromes would have to be included that are beyond the scope of this text.
|GLAUCOMA SECONDARY TO CONGENITAL CATARACT SURGERY|
|Both open and angle closure glaucoma can occur after congenital cataract
surgery, although the open-angle variety occurs much more commonly. Open-angle
glaucoma after congenital cataract surgery has been reported
to occur in 3% to 41% of patients, depending on the series.29 The glaucoma may be of a congenital variety or may be associated with
the cataract surgery itself. As opposed to congenital glaucoma, glaucoma
after congenital cataract surgery is usually asymptomatic despite high
intraocular pressures.30 |
There are many possible causes, including lens remnants with swelling, postoperative uveitis with occlusion of the pupil and peripheral anterior synechiae, and postsurgical flat anterior chambers with resultant synechia of the angle. Blockage of the pupil by vitreous may occur. Hyphema and, rarely, epithelial invasion of the anterior chamber have been noted. The uveitis may result from the presence of virus (as in the rubella syndrome), the surgical procedure itself, or retained lens particles. Measures directed toward each of these etiologies can be instituted. One report31 indicates that even though the angle remains completely free of any debris or inflammation, glaucoma may ensue after congenital cataract surgery. This glaucoma may result from underlying angle anomalies and could represent the coexistence of congenital glaucoma and cataracts. The postoperative appearance of the angle with an anterior iris insertion and prominent uveal scleral meshwork supports this. The time interval between the original cataract surgery and the onset of glaucoma is variable, with glaucoma occasionally occurring many years later.32 Thus, patients should be followed indefinitely for pressure stability, even if this requires examination under anesthesia.
Interestingly, aphakia may be a risk factor for open-angle glaucoma. Research suggests that placing a posterior-chamber intraocular lens during congenital cataract surgery significantly decreases the incidence of postoperative glaucoma, although the mechanism for this is unclear.33
Treatment for postcataract surgery glaucoma is usually the same as that for open-angle glaucoma, with medications being the initial modality of choice. Surgical intervention is shown to have limited success.34
|With blunt ocular trauma there may be an immediate rise in pressure or, if
the trauma is of sufficient magnitude, a delayed rise years later
in a small percentage of patients. The trauma may induce an angle recession,35 and in many of these traumatized eyes a contusion cataract ensues with
either subluxation or dislocation of the lens. Rarely the lens may become
swollen and intumescent, giving rise to phacolytic glaucoma, or, because
of mechanical reasons, pupillary block glaucoma. Steroid use for
iritis or other conditions after trauma is associated with an increased
risk of ocular hypertension and cataract formation, especially if
steroid use is prolonged. |
If the lens anomaly is the cause of the glaucoma or visual impairment resulting from cataractous changes is present, removal of the lens may be indicated. A peripheral iridectomy in the presence of a subluxated clear lens may relieve the glaucoma. The treatment of angle-contusion glaucoma is essentially the same as for open-angle glaucoma, regardless of age.
If hyphema is present, a secondary glaucoma may result. This is more commonly seen in the eight-ball or total anterior chamber hemorrhage. In these patients, cataracts, either of posterior subcapsular or anterior subcapsular location, often are seen. Treatment is directed toward control of the bleeding. If blood staining of the cornea or intractable intraocular pressure ensues, irrigation of the chamber may be attempted. Various methods, including diathermy, fibrinolysis, and cryoextraction of the clot, have been tried in the treatment of this difficult problem.31 Essentially, treatment has to be individualized because there is no commonly accepted mode of therapy.
|CATARACTS AND PRIMARY ANGLE-CLOSURE GLAUCOMA|
|The lens plays a vital role in primary angle-closure glaucoma. It is involved in the physiologic block of forward aqueous flow and, in turn, can develop opacities as a result of the acute rise in pressure. Because of the forward position of the lens in eyes with genetically determined shallow anterior chambers, the resistance to aqueous flow caused by apposition of the iris to the lens lifts the peripheral iris forward toward the trabecular meshwork and often causes angle closure. In addition to the anterior position of the lens in such eyes, intumescence or swelling of the lens or a slightly anteriorly dislocated lens may cause the same problem. This latter factor is discussed in the section on secondary angle-closure glaucoma and cataracts.|
|ANGLE-CLOSURE GLAUCOMA CAUSED BY PUPILLARY BLOCK|
|Cataracts are often the cause of angle-closure glaucoma resulting from
pupillary block. Lenticular opacities may appear and are felt to be characteristic
of this variety of glaucoma. They have been called glaukomflecken, are
of a subepithelial nature, and usually are found underneath
the anterior capsule.36 The presence of these punctate opacities in quiet eyes usually indicates
previous attacks. However, it has been noted that they may occur in
patients with glaucoma with high intraocular pressure associated with
contusion injury or iridocyclitis.37,38 After an attack, these opacities may progress from multiple discrete subcapsular
spots to round or oval densities, usually located in the pupillary
area. Apparently, these result from necrosis of the subcapsular
epithelium as a result of the high intraocular pressures.39 However, these are not related to all cases of angle closure and seem
to be dependent on the level of pressure, the number of previous attacks, and, possibly, the
duration of the attacks. In addition to these lens
opacities, senile cataracts can be precipitated or, even more often, aggravated
by acute angle-closure episodes.|
If the cataract is of such a nature to decrease vision significantly, the treatment is cataract removal and iridectomy. It is well known that treatment with parasympathomimetic agents, such as pilocarpine, has been implicated in the formation of lens opacities,40 although this may be related to older studies of its previous long-term use in open-angle glaucoma rather than short-term use in angle-closure glaucoma. Miotic therapy is discussed in further detail later in this chapter.
A peripheral iridectomy is the treatment of choice for pupillary block glaucoma. Most iridectomies today are performed by laser, although surgical iridectomies are still performed in many parts of the world. The incidence of lens opacities after surgical peripheral iridectomy is increased, usually related to direct injury from a surgical instrument. Meticulous care at the time of surgery may decrease the incidence of direct traumatic cataracts.38 Prolonged flat anterior chambers occurring after peripheral iridectomy also may lead to a higher incidence of cataracts.
Although the advent of laser iridotomy has greatly decreased the incidence of cataract development compared to surgical iridotomy, laser iridotomy (Fig. 4) also can cause lenticular changes. Several reports have demonstrated small lens opacities appearing at the site of the laser beam after laser iridotomy (Fig. 5),36,41,42 but no progression of these opacities has been described. Zonular rupture can occur from the laser as well.43 One case report describes an “exploding” cataract with posterior capsular rupture and release of cortical material into the vitreous following a YAG laser peripheral iridectomy.37
Regardless of whether cataracts are associated with iridectomies, this intervention is still the treatment of choice in primary angle-closure glaucoma in which the cataract causes reversible visual loss, but glaucomatous damage to the nerve is irreversible.
|Plateau iris and cataracts are rarely discussed in the literature, perhaps because of the rarity of the plateau iris configuration. In contrast to the primary pupillary block glaucoma with angle closure, plateau iris is known to be associated with a deep central anterior chamber and an anterior iris insertion on the ciliary body. Acute attacks usually are precipitated by dilation of the pupil, and it is conceivable that if the pressure rises high enough and is of long duration, lens opacities such as glaukomflecken could occur. Peripheral iridectomy may be considered to relieve any small element of pupillary block, but in some cases the patient is still predisposed to develop angle closure and thus requires long-term miotic therapy. Therefore, cataracts can be caused by surgical trauma or flat anterior chambers if the iridectomy is performed surgically or because of the need for chronic miotic therapy. Another treatment option for plateau iris is argon laser peripheral iridoplasty, which flattens the peripheral iris by thinning it. In most cases, this procedure lasts for many years, although in some instances a gradual reclosure of the angle requires repeat iridoplasty.44|
|CATARACTS AND OPEN-ANGLE GLAUCOMA|
An extensive review of currently published literature fails to find a correlation between open-angle glaucoma itself and cataracts. However, surgeries for either glaucoma or cataracts can lead to formation of the other. Some medical therapies for glaucoma can be associated with cataract formation, but most of these have been replaced with noncataractogenic medications.
Visual field testing may be altered by the presence of cataracts, potentially leading to the false interpretation of glaucomatous damage (Fig. 6).45 When both the optic nerve and visual field cannot be evaluated because of lenticular opacities, then the clinician must rely most heavily on the binocular status of the patient, the level of intraocular pressure, and the results of the last reliable examination. Lens extraction generally is justified if management of the glaucoma is hindered by the cataract, such as in unreliable visual field results or poor visualization of the optic nerve.
|GLAUCOMA MEDICAL THERAPY|
|In the past, the mainstay of glaucoma treatment was miotic therapy, which
is well known to be related to cataract formation. This is discussed
in detail in the next section. The pharmaceutical agents most commonly
used to treat open-angle glaucoma today include:|
An extensive review of the literature found no association between glaucoma medications from the listed categories and cataract formation.
|Miotics can alter both distance and near vision in patients who have cataracts. Less
light enters the eye with a miotic pupil and the area of
clear lens is reduced, especially when central (e.g., posterior
subcapsular) opacities are present. |
Miotic therapy itself, in addition to reducing the visual acuity in those with pre-existing cataracts, has been noted to be cataractogenic.40,46 The most common association is with the anticholinesterases.47 Lens opacities have been noted in more than 50% of patients treated for a long period with strong anticholinesterases. The exact mechanism of cataract formation after the use of anticholinesterases has not been elucidated, and articles even argue against a causal relationship.48 Other reports, however, implicate the long-term use of anticholinesterases in concentrations greater than 0.06%. Whether the cataracts are reversible is debatable and seems to depend on the age of the patient being treated. Lens opacities in younger people are more likely to be reversible.49
The bottom line is that miotic therapy can be both cataractogenic and visually disturbing because of pupillary constriction. Luckily, miotic therapy has been largely replaced with therapies that are neither cataractogenic nor cause pupillary constriction; therefore, miotic therapy should generally be reserved as a last-line agent for open-angle glaucoma.
In the exfoliation syndrome (pseudoexfoliation), fibrillar material is scattered throughout the anterior chamber of the eye. Histochemically the material is similar to amyloid. It has been found in and on the lens epithelium and capsule, lens zonular fibers, ciliary epithelium, pupillary margin, iris pigment epithelium, iris stroma, iris blood vessels, corneal epithelium, and subconjunctival tissue (Fig. 7).50,51 On the anterior lens capsule, a peripheral zone of exfoliative material is separated from a central zone by a clear area, presumably from the iris rubbing away the material. The source of the material is not yet known, but it appears unlikely that the lens is the sole source of the particles as deposits of material persist after cataract extraction. It is assumed that multiple sources contribute as part of a generalized basement membrane disorder. Exfoliation syndrome is a systemic disease, as fibrillar material has been found in connective tissue portions of various visceral organs.52 This syndrome is most commonly found in elderly patients.
The anterior chamber angle in pseudoexfoliation exhibits a heavily pigmented trabecular meshwork and an inferior pigmented deposition anterior to Schwalbe's line (Sampoelesi's line). Often the angle is narrow, presumably from anterior displacement of the lens secondary to zonular weakness. Exfoliation syndrome is the most common cause of glaucoma identified. It can cause both open-angle and angle-closure glaucoma in all populations, and accounts for the majority of cases in some countries.52
Cataract and glaucoma filtering surgery are both complicated by the presence of pseudoexfoliation. In cataract surgery, zonular weakness can lead to an increased risk of vitreous loss, among other possible complications.53 Some experts argue that cataract extraction ought to be performed earlier in patients with pseudoexfoliation, when lenses are softer and zonules are stronger. The advent of capsular tension rings is a major advance for cataract surgeons in dealing with lens instability from pseudoexfoliation, with studies showing decreased complications from zonular separation, with an increase in capsular fixation of intraocular lenses and improved final visual acuity.54 Interestingly, in one study patients with pseudoexfoliative glaucoma exhibited a 2 mm Hg greater decrease in intraocular pressure (IOP) at 6 months following cataract surgery when compared to patients with primary open-angle glaucoma. However, this difference became small after the 6-month period.55
Retinal detachments often produce hypotony rather than glaucoma. As a result of inflammation, trauma, pigment debris, or other unknown factors, glaucoma may ensue, but can often be cured by the successful reattachment of the retina.56 Detachments can be associated with posterior subcapsular opacities, and these may progress to dense cataracts. When the cataract matures, it cannot be distinguished from other types of senile cataracts.
Retinal detachment can occur after either cataract surgery or Nd:YAG laser capsulotomy. The estimated risk of retinal detachment in patients who undergo cataract surgery is 1% to 3%.57 Detailed ophthalmic examination and repair of any lesion that can contribute to a retinal tear is advised before cataract surgery or Nd: YAG laser capsulotomy.
Retinal detachment repair procedures may be associated with subsequent glaucoma and cataract formation. This is discussed in the section on secondary glaucoma.
Retinitis pigmentosa is associated with open-angle glaucoma58 and cataracts of a posterior subcapsular type. The incidence of glaucoma has been reported from 3% to 12%,39,59 and the incidence of cataracts may be higher.56 Treatment for glaucoma is the same as for traditional open-angle glaucoma. The cataract can be approached conventionally if vision is threatened.
In high myopia (> −5.00 diopters), there is an increased incidence of open-angle glaucoma, with an estimated occurrence rate from 5% to 18%.60 In addition, cataracts of the posterior cortex may complicate high myopia but do not occur until after middle age.60
The treatment of the glaucoma is the same for open-angle glaucoma. In removal of the cataract, the thin and weakened scleral shell and retina must be approached cautiously. There is a much higher risk of retinal detachment after cataract surgery in highly myopic eyes, even with modern surgical techniques.60
Implantation of a phakic implantable contact lens for high myopia may lead to several complications, including pigmentary dispersion, angle-closure glaucoma, and cataract formation.61
Open-angle glaucoma may occur in up to 15% of patients with Fuchs' endothelial dystrophy.39 Patients with already narrow angles can develop angle closure with thickening of the cornea from edema.62 There is no increased incidence of cataracts in this disease over that found in the general population, although cataract formation can follow keratoplasty.63 This is in contrast to Fuchs' heterochromic-iridocyclitic syndrome, in which glaucoma and cataracts are essential features.
The therapeutic approach for glaucoma in these patients is the same as in traditional open-angle glaucoma. Because of the corneal findings and often concomitant cataracts, combined keratoplasty with cataract extraction frequently is needed in these eyes. The dystrophic changes in the endothelium (Fig. 8) must be estimated when glaucoma and cataract surgery are planned. If the endothelium is not severely damaged and cataract is present, it may be possible to obtain good pressure control and visual results for a long period of time with combined cataract-glaucoma procedures, when necessary.
Both open-angle glaucoma and cataracts may occur more commonly in those with diabetes mellitus.64 Furthermore, the presence of diabetic retinopathy may affect perimetric results.65 The management of the patient with open-angle glaucoma, diabetes mellitus, and cataracts is the same as for a patient with uncomplicated open-angle glaucoma. Clinical progression or aggravation of diabetic retinopathy may occur after cataract extraction or filtration surgery. Medical and surgical management of patients with these three diseases must be tailored to suit the needs of each individual. Luckily, modern surgical techniques of phacoemulsification have greatly reduced the risk of ocular complications in diabetics. Macular edema before surgery is the diabetic ocular condition most likely to limit postoperative visual recovery. Laser photocoagulation of preproliferative or early proliferative diabetic retinopathy is recommended before cataract extraction.66
The insertion of an intraocular lens in patients with ocular hypertension or glaucoma does not appear to negatively affect pressure control in most cases.67 Pupillary block can occur in both pseudophakic and aphakic eyes. When this occurs, the anterior chamber generally shallows with the formation of iris bombé (Fig. 9). As opposed to typical angle-closure situations where miotics are used, pupillary block is treated with mydriatic agents to re-establish aqueous flow through the pupil. Peripheral laser iridotomy is curative in most cases, although often it has to be repeated because of a tendency to lose patency.68
Pupillary block occurs quite frequently after the placement of an anterior chamber intraocular lens subsequent to cataract surgery (Fig. 10). Thus it is generally recommended to create a peripheral iridectomy at the time of surgery when placing an anterior chamber intraocular lens. Although rare, pupillary block glaucoma also can occur after posterior chamber intraocular lens implantation, even years after the original surgery.68
|CATARACTS AND SECONDARY GLAUCOMA|
|Secondary glaucoma and cataracts can occur with a variety of underlying
Iridocyclitis can occur in a wide spectrum of systemic diseases. Juvenile rheumatoid arthritis is a common systemic cause of a chronic anterior uveitis complicated by cataracts and glaucoma.69 These patients often are asymptomatic; thus, regular comprehensive ophthalmologic examinations are essential.
Another common cause of iridocyclitis is sarcoidosis, for which granulomatous iridocyclitis is the most frequent ocular manifestation.70 Up to 72% of patients may have either acute or chronic iridocyclitis. Macular edema, cataract, and glaucoma are other ocular complications seen in this disease. In one study of Japanese patients, 15% of the participants with sarcoid uveitis eventually demonstrated a poor visual outcome because of ocular complications.71
Treatment of iridocyclitis includes attempts to control the inflammatory process with steroids, mydriatics, and cycloplegics, in addition to the standard antiglaucoma therapy. Miotic agents usually are avoided because they can worsen inflammation and lead to posterior synechiae of the iris to the lens. The response often is disappointing. An important factor to consider in the treatment of patients with iridocyclitis is the side effects of topical steroids, especially the hastening or aggravating of the underlying secondary glaucoma or cataractogenesis.
FUCHS' HETEROCHROMIC IRIDOCYCLITIS
Open-angle glaucoma occurs in 20% of the involved (hypochromic) eye in heterochromic iridocyclitis.39 Despite the fact that small neovascular twigs are seen on the iris root, neovascularization does not complicate the glaucoma. Low-grade iritis, an underlying defect in the trabecular meshwork, and hyaline membrane proliferation are factors in the glaucoma.15 Although depigmentation of the iris occurs, little pigmentation is noted in the trabecular meshwork.72 The incidence of cataracts is high, ranging from 17% to 70%.73 The cataracts usually begin as fine punctate opacities and progress to maturity.
The glaucoma is treated using the medical and surgical approaches generally used for traditional open-angle glaucoma. Glaucoma and endothelial difficulties make cataract extraction more hazardous,39 but most patients fare well after surgery.74 There is some literature pointing to the benefits of using heparin surface–modified intraocular lenses in patients with heterochromic uveitis.75,76
Tumors can cause secondary glaucoma in a variety of ways: inflammation from necrotic tumors, direct angle invasion, peripheral synechiae as a result of inflammation,77 and mechanical shallowing of the anterior chamber. Cataracts occasionally occur as a result of a tumor and usually consist of posterior cortical opacities resembling those seen in posterior segment disease. In the presence of a cataract, secondary glaucoma, and retinal detachment, an underlying tumor should be suspected and evaluation with the appropriate ultrasound and scanning procedures must be undertaken.
Secondary open-angle glaucoma is seen in 10% of patients with interstitial keratitis in later life.15 The etiology of the glaucoma varies. Angle closure has been seen, but the angle appears open in the majority of those examined gonioscopically. Iris cysts,78 irregular peripheral anterior synechiae, and the possibility of a membrane covering the angle79 are reported as causes of the secondary open-angle glaucoma. Cataracts of various types, ranging from posterior cortical opacities to mature types,2 may occur. In late cases of interstitial keratitis now quiescent, it is difficult to determine if earlier treatment of the anterior segment inflammation with steroids played a role in the formation of glaucoma and cataract.
Treatment depends on the type of glaucoma present: peripheral iridectomy is used for angle closure glaucoma and the usually medical-surgical regimen is followed for the open-angle glaucomas. The surgeon must take into account the presence of corneal disease when planning cataract surgery.
Phacolytic glaucoma usually is seen in eyes with open angles, with a mature or hypermature cataract, and anterior chamber inflammation (Fig 11). The events leading to elevated pressures are: (a) lens material leaks through the lens capsule, (b) macrophages engulf the material, and (c) lens substance, macrophages, and other inflammatory material are carried by the aqueous currents to the angle, clogging the trabecular meshwork and obstructing the outflow passages.
Clinically, phacolytic glaucoma usually presents in an elderly patient with worsening vision, pain, conjunctival injection, elevated IOP of 30 to 50 mm.80
LENS PARTICLE GLAUCOMA
An inflammatory reaction to retained lens material can occur any time from days to years after cataract surgery. Elevated IOP occurs along with anterior chamber cellular reaction. Free cortical material sometimes can be seen in the anterior chamber and microcystic corneal edema, posterior, and peripheral anterior synechiae may develop. Medical therapy aimed at decreasing aqueous formation, corticosteroids to reduce inflammation, and mydriatics to help prevent formation of posterior synechiae are mainstays of treatment. Surgical removal of the lens material is required in some cases refractory to medical therapy.80
In phacoanaphylaxis, patients become immune-sensitized to their own lens protein after surgery or trauma. Although this results in a granulomatous reaction, glaucoma is rare. This disorder is differentiated from phacolytic glaucoma by the presence of keratic precipitates. Treatment is the same as for lens particle glaucoma.80
GLAUCOMATOCYCLITIC CRISIS (POSNER-SCHLOSSMAN'S SYNDROME)
Glaucomatocyclitic crisis is characterized by a recurrent cycle of unilateral bouts of mild, nongranulomatous iritis with elevated IOP. Studies have shown that as many as 45% of patients with this syndrome also have primary open-angle glaucoma.81,82 Posner-Schlossman's syndrome itself also can cause glaucomatous damage; therefore, these patients need to be monitored as if they had glaucoma.83 Treatment is usually medical and includes the use of topical steroids. Some of these patients develop posterior cortical opacities, but whether these are caused by steroid treatment or the underlying anterior segment inflammation is not clear.
Nearly all forms of steroid use have been associated with ocular side effects, including topical, oral, inhaled, and intravenous.84 To date, nasal steroids have not been associated with any significant ocular side effects.85 Even periorbital topical steroid use has been linked to ocular complications, such as in a case report of bilateral glaucomatous damage in a 29-year-old woman using topical steroids around her eyes.86 Glaucoma can develop at any time during the use of corticosteroids.
Steroid-induced glaucoma, which was recognized as early as 1950,87 resembles open-angle glaucoma in many aspects: The normal angle appears open by gonioscopy, the facility of outflow decreases, the optic nerve is damaged, and visual fields decrease as a result of increased IOP.
Topical steroid use shows the greatest incidence of IOP elevation. The incidence of a rise in IOP induced by the use of topical steroids in a normal population is between 6% and 30%,88 above 30% in those cases with a family history of glaucoma,39 and 75% to 90% in patients with glaucoma.89 In different studies, different criteria for separating responders from nonresponders have been used. Hence, the percentages listed vary from study to study. The results depend on the type of steroids used and the pressure levels chosen for responsiveness or nonresponsiveness. There is no doubt, however, despite the wide ranges and results, that topical steroid use can significantly raise the IOP leading to permanent visual damage if left untreated.
The reason for steroid-induced elevation of IOP is unclear. Cells of the trabecular meshwork contain steroid-specific receptors, and it is theorized that corticosteroids may alter the expression of trabecular meshwork genes by activating these receptors, eventually leading to increased resistance of aqueous humor outflow. Other theories have been published, but no conclusive findings have been elicited.90–92
Treatment may consist of medications aimed at lowering IOP, discontinuing or reducing the frequency of the corticosteroid, or substituting the corticosteroid for a weaker one. Intraocular pressure often returns to baseline within 2 to 4 weeks after cessation of topical steroids.93 Some patients may require surgical intervention.
Nearly all forms of corticosteroids have been linked to cataract formation as well. They are usually posterior subcapsular in location. Cataracts induced by topical steroids are noted in 21% to 36% of cases studied.94 The relationship of systemic corticosteroid use and cataract formation was first described in 1960.95 The overall incidence of cataract formation with systemic corticosteroid use ranges from 6% to 38%. Although quite variable, increased dosage and duration of corticosteroid use generally is related to increased incidence of cataract formation.96 Diabetic patients treated with topical steroids are more prone to develop these opacities.97 As with corticosteroid-induced glaucoma, the pathophysiology of cataract formation with steroid use is not clear.
Management of steroid-induced cataracts is similar to other adult cataract types, except that in cases of steroid use for intraocular inflammation it is generally recommended to control the inflammation as much as possible before cataract extraction.
Secondary open-angle glaucoma and cataracts may occur as a result of trauma. In nonpenetrating injuries of the eye, contusion angle deformity or recession of the angle can cause secondary glaucoma, either acutely or chronically. Mechanisms include disinsertion of the ciliary muscle from the scleral spur, meshwork sclerosis or fibrosis, or hyaline membrane formation. Cataracts may occur in 24% of patients with contusion injuries, varying from hypermature to cortical types.98
The open-angle glaucoma is treated medically or surgically, with the realization that some treatments, such as miotics, may be ineffective because of disruption of the normal ciliary muscle–scleral spur relationship. Cataract surgery is approached as adult cataract surgery, keeping in mind that subluxation of the lens and vitreous loss may complicate the lens extraction. Capsular tension rings may be useful in these cases.
LENS-INDUCED SECONDARY ANGLE-CLOSURE GLAUCOMA
In lens-induced (phacomorphic) secondary angle-closure glaucoma, a swollen, cataractous lens, because of its shape and size, induces a pupillary block and closes the angle. Comparison of the involved eye with the contralateral eye often helps distinguish this form of induced glaucoma from that of narrow-angle glaucoma with pupillary block, in which both eyes are anatomically similar. Removal of the lens is the treatment of choice. Mydriatics and cycloplegics, as well as steroids, may help prepare the patient's eye for surgery.
In ectopia lentis, anterior displacement of the lens can cause pupillary block, resulting in an acute attack or chronic angle-closure glaucoma. Common causes of ectopia lentis include trauma, Marfan's syndrome, homocystinuria, Weill-Marchesani's syndrome, and microspherophakia. Laser iridectomy is the treatment of choice. Often, after direct trauma that results in a subluxated lens and angle closure, a cataract forms, and removal of the lens is indicated. Furthermore, if iridectomy does not relieve the pupillary block, then lens extraction is indicated. Capsular tension rings, perhaps with scleral fixation, may be useful in these cases.
|In the surgical therapy of open-angle glaucoma, many reports have attempted
to elucidate the most appropriate approach to patients with concomitant
cataracts.99,100 In deciding which surgical approach to use, one must be cautious, because
surgery may cure one and complicate the other. It is fairly well established
that filtration surgery is complicated by hastening formation
of the cataract.100 The exact incidence varies with the technique, length of follow-up, and
age of the patient. The complication of lens opacities has been appreciated
in the past and has become evident even with the newer microsurgical
techniques that minimize hypotony and flat anterior chambers and
more quickly re-establish normal aqueous humor dynamics.101 The complication of cataract formation as a result of filtration surgery
needs to be considered in the surgical management of the open-angle
glaucoma patient with cataracts.|
For patients with both cataracts and glaucoma requiring surgical intervention, the various approaches are: (a) filtration surgery with possible cataract extraction later, (b) cataract extraction alone with possible filtration surgery later, and (c) a combination of filtration surgery and cataract extraction. Whether or not to combine cataract and glaucoma surgery is a topic of great controversy among ophthalmic surgeons, and is probably most dependent on the patient's individual situation.
Combined phacoemulsification and trabeculectomy (phacotrabeculectomy) has a better IOP-lowering effect than phacoemulsification alone.102 However, numerous studies suggest that trabeculectomy alone has superior IOP-lowering effects than combined phacoemulsification and trabeculectomy in lowering IOP, although the reason is unclear.103,104 One hypothesis is that phacoemulsification increases trauma to the wound. When phacotrabeculectomy is performed, the concomitant use of mitomycin C leads to a significantly lower IOP of 2 to 4 mm Hg.105
There are conflicting reports on the effect of phacoemulsification on IOP and bleb performance after trabeculectomy. Some studies have reported improved IOP, whereas others have shown worsening IOP. However, it is not clear if elevated IOP is simply the natural course of glaucoma, unrelated to the cataract surgery. Overall, it seems that phacoemulsification with clear corneal incision does not affect IOP, but increases 3-year bleb failure rates.106 Cataract surgery performed within 6 months of trabeculectomy, iris manipulation, and age younger than 50 years all seem to be risk factors for failure of a filtering bleb.107
Perhaps patients with open-angle glaucoma can benefit from cataract extraction alone. Some studies have demonstrated that phacoemulsification alone can reduce IOP long-term by 2 to 4 mm Hg.102 However, it is also known that some patients demonstrate a long-term increase in IOP after cataract extraction.99,108 Early postoperative spikes in IOP also are common, although these tend to resolve quickly and may be diminished by the postoperative use of pressure-lowering medications.109,110 The most commonly encountered clinical scenario for concomitant glaucoma and cataracts is a patient with well-controlled glaucoma, and a cataract for which isolated cataract surgery is currently the most common therapy.
For angle-closure glaucoma, cataract surgery alone significantly improves IOP regulation, with one study reporting an IOP reduction of 7 mm Hg 2 years after surgery.108 Therefore, a patient with angle-closure glaucoma with even mild lenticular opacities should undergo cataract extraction before any other surgical intervention is considered. In the event of total synechial angle closure, 180-degree goniosynechialysis and peripheral diode laser iridoplasty could be performed at the time of phacoemulsification.111
It is certain that the topic of combined versus separate procedures for glaucoma and cataracts will continue to be a controversial topic. Hopefully, as new studies are published the “rules” will become clearer. Table 1 provides some general guidelines from one major meta-review, although each patient's individual situation must be considered and discussed.106
|The authors and editors wish to acknowledge with appreciation the contributions of William E. Layden, MD, author of the previous edition's chapter. Some of the information, including illustrations, has been incorporated into this edition.|
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