Glaucoma in Young People
he number of younger people (under 35 to 40 years) with glaucoma has been vastly underestimated in the past.
A major reason for this is that for a long time, ophthalmologists as well as patients have thought of glaucoma as a disease with variations. However, realizing that glaucoma represents a final common pathway resulting from a number of different conditions which can affect the eye, it should be almost a priori that some of these conditions would affect infants, children, adolescents, and young adults. In this context, there are a number of different diseases which can cause glaucoma in the under 40 age group. Glaucoma is also common after surgery for congenital cataracts.
CONGENITAL glaucoma, or INFANTILE glaucoma, affects about 1 in 10,000 live births. It may occur without other findings (primary congenital glaucoma), associated with other syndromes, or after injury, congenital cataract extraction, or inflammation. Primary congenital glaucoma is due to failure of development or abnormal development of the trabecular meshwork. Most cases of primary congenital glaucoma are sporadic in occurrence. In the approximately 10% in which a hereditary pattern is evident, it is generally believed to be autosomal recessive in most cases.
Congenital glaucoma is usually detected by the parents. In infancy, the sclera of the eye is easily distensible, so that the eye enlarges when IOP is increased. Breaks occur in the corneal endothelium, leading to edema, or swelling, of the cornea, which produces a hazy, frosted glass appearance. The baby is sensitive to light and tearing may be present. As the cornea stretches, ruptures allow more aqueous into the corneal stroma and epithelium, causing a sudden increase in edema and haze and an increase of tearing and photophobia. The infant may become irritable to the point of burying its head in a pillow to avoid the pain caused by bright lights.
Treatment is surgical and often successful, although more than one operation may be necessary. The prognosis is worse if the glaucoma is present at birth.
Pigment dispersion syndrome (PDS)
This is a genetic disorder (autosomal dominant so that 50% of children and siblings and one parent have the disease) affecting primarily Caucasians (95%). The prevalence of PDS has been vastly underrecognized and it is often not diagnosed on eye examination because of a low index of suspicion. The gene may be present in as many as 2% of the Caucasian population. It is expressed more commonly in myopes (nearsighted persons).
About 5-10% of people carrying the gene develop glaucoma, which usually develops between ages 20 and 40. The greater the myopia, the earlier the glaucoma develops. Men develop glaucoma about 3 times as often as women. It most often begins in the twenties and thirties, which makes it particularly dangerous to a lifetime of normal vision. Pigmentary glaucoma is the most common glaucoma in persons under age 40, and it is far more common than previously suspected.
Because most of these patients are in their 20's, they don't get checked for glaucoma routinely, and it is all too common for the diagnosis to be made after someone has become blind in one eye. Patients fitting this description may complain of blurred vision and worsening vision and still not have their pressures checked or visual fields performed because they were told they were too young to have glaucoma.
The anatomy of the eye plays a key role in the development of pigmentary glaucoma. Myopic eyes tend to have a concave-shaped iris which creates an unusually wide angle. In pigment dispersion syndrome, the iris seems to be extra large, so that it becomes even more concave. This causes the pigment layer of the iris to rub against the zonules, which are like wires holding the lens in place. This rubbing action causes disruption of the posterior pigmented epithelial cells of the iris, releasing pigment particles into the aqueous humor. The pigment is deposited throughout the anterior segment, including the trabecular meshwork, which becomes densely clogged with pigment, visible on examination.
Miotic therapy is the treatment of choice, but these drugs in drop form can cause disabling visual blurring in younger patients. Fortunately, a slow-release form, pilocarpine Ocuserts, are well tolerated by younger individuals. Laser iridotomy is presently being investigated in the treatment of this disorder.
Juvenile primary open-angle glaucoma
This is also strongly hereditary. The gene has been localized in five large families from 3 countries to the short arm of chromosome 1. It is defined as primary open-angle glaucoma appearing between ages 10 and 35. It affects all races. About 35% of people with this disease are high myopes (very nearsighted), and 85% total are nearsighted.
Sturge-Weber syndrome is relatively common and everyone has known someone at one time or another with a port-wine stain on the face. When the port-wine stain affects the forehead and upper lid, glaucoma occurs about two-thirds of the time. It can occur at birth or infancy, but more commonly develops between ages 9 and 16. For some reason, this has not been well known, and many children are only detected after they have suffered severe damage. Sturge-Weber Syndrome is a common cause of blindness from glaucoma in childhood. Most of this blindness could be prevented through timely diagnosis and appropriate treatment.
Ocular manifestations of Sturge-Weber syndrome occur in infancy and early childhood. The hallmark of the disorder is a facial cutaneous angioma (nevus flammeus, port wine stain), which is present at birth, is unilateral in 90% of affected children, and involves the region of distribution of the first and second divisions of the trigeminal (fifth) nerve . The first division corresponds to the forehead and upper eyelid. The second division corresponds to the cheek and lower eyelid. The third division corresponds to the jaw.
Vascular malformations may affect the eyelids, sclera (the white wall of the eye), conjunctiva, and iris. When the upper lid is involved, the eye is also usually involved. The iris may appear darker than that in the opposite eye. Vascular malformations of the choroid, the spongy vascular tissue which lies between the retina and the sclera, in about 40% of affected eyes. They are easily overlooked in younger patients and grows slowly.
One third of patients with Sturge-Weber syndrome have increased IOP. This is characteristically on the same side as the vascular malformation, although glaucoma can sometimes occur bilaterally. Glaucoma can occur at various stages in life, but most commonly occurs in infancy and childhood.
Glaucoma may be present at birth or develop in the first few years of life. This is called congenital glaucoma. Congenital glaucoma results from developmental abnormalities that result in malfunction of the tissue which drains fluid from the eye. It is usually detected by the parents. The most characteristic signs of congenital glaucoma are enlargement of the eye, a hazy cornea, tearing, and photophobia (the baby tries to hide its head from bright light). All babies with Sturge-Weber syndrome should have intraocular pressures measured in infancy and, if normal, once a year thereafter. The treatment for congenital glaucoma is surgery.
After the age of three or four, the eye wall becomes thicker and does not enlarge when the intraocular pressure rises, and it is necessary to measure IOP in order to determine the presence or absence of glaucoma.
The development of glaucoma during childhood and adolescence is also common. These children usually have a vascular malformation of the sclera, which causes elevated pressure in the veins which drain the eye. This, in turn, causes IOP to rise, with subsequent damage to the drainage system of the eye. Medical treatment (eyedrops) may control this type of glaucoma. If medical treatment fails, surgical intervention becomes necessary. Laser treatment for the glaucoma is ineffective.
With early diagnosis, and appropriate treatment geared to the type of glaucoma and the findings from examination of the eye, the glaucoma can often be controlled and vision preserved.
Aniridia is a hereditary condition uniformly associated with iris abnormalities. This development disorder is rare, occurring in approximately 1 in 50,000 live births. Typically, the iris appears as a small rudimentary stump associated with a large pupil. Aniridia may be associated with congenital glaucoma, but glaucoma most commonly develops in childhood or adolescence. Other abnormalities include cataract, failure of the macula to develop, nystagmus, and corneal vascularization.
Three genetic types of aniridia have been recognized. About 85% of patients have isolated, autosomal dominant aniridia (not associated with other systemic manifestations). About 13% have autosomal dominant aniridia associated with Wilms’ tumor, genitourinary anomalies, and mental retardation (WAGR), while 2% have autosomal recessive aniridia associated with cerebellar ataxia and mental retardation. The aniridia gene, now called the PAX6 gene, has been established as the only genetic locus for aniridia andgene is located on chromosome number 11.
Treatment of congenital glaucoma is the same as for primary congenital glaucoma. Long-term treatment of childhood glaucoma is difficult, complicated, and often frustrating, but is constantly improving.