Congenital Glaucoma

Overview of congenital glaucoma

Eye problems are common in children. They may arise from nutritional deficiencies or environmental triggers. Many of these problems occur due to some major birth defects. “Congenital glaucoma” is a disease of this category. It is one of the leading causes of blindness in children. In the recent years, congenital glaucoma has become one of the primary health concerns worldwide. Families having a history of congenital glaucoma should be very cautious about the development of similar symptoms in the future generations.

What is congenital glaucoma?

Congenital glaucoma is a genetic retinal disease in which, damage of the optic nerve, defective intraocular drainage and increase in intraocular pressure may occur. Loss of peripheral and central vision occurs in many cases. Congenital glaucoma arises mainly due to some structural abnormalities of the drainage system of the eyes. The fluid flow from the aqueous humor is obstructed in such cases. This causes an abnormally high intraocular pressure. The common manifestations of this condition are the premature elongation of the eyeball, abnormal enlargement of the cornea and corneal edema. All these abnormalities are attributable to a faulty angle of the eye chambers at the region of the junction with the trabecular meshwork. The degree of ocular damage (glaucomatous damage) depends on the total duration of the disease.

What causes congenital glaucoma?

Congenital glaucoma results from multiple etiological factors. The main causes are discussed below-

• Structural defects of the drainage system of the eyes
• Defective angles of the eye chambers at the region of the trabecular meshwork
• Clogging of the pores of the trabecular meshwork due to the accumulation of iris pigments
• Defective drainage and accumulation of the intraocular fluid
• Abnormal increase in the pressure of the eye chambers due to excess build-up of fluid
• Damage of the sensory optic nerve fibers due to high intraocular pressure
• Progressive hollowing of the optic disc that causes the optic nerves to bend into a curvature

What are the warning signs of congenital glaucoma?

The signs and symptoms of congenital glaucoma are usually present at birth. The common alarming symptoms of the disease are as follows-

• Gradual cloudiness of one or both eyes (present at birth or develops later)
• Abnormal enlargement of the eyeballs
• Distortion of the eyeball shapes
• Continuous rubbing, itching, and poking of the eyes
• Constant watering from the eyes (epiphora)
• Redness and swollenness of the eyes
• Photosensitivity (the child may turn his face away from bright light and try to hide it in a pillow or any other object)
• Extreme tenderness of the eyes (child may cry on touching the eyes)
• Corneal edema (abnormal swelling of the cornea)
• Hazy or greyish discoloration of the cornea
• Vision disturbances
• The child may cry continuously and present signs of irritability
• Difficulty feeding the baby
• Vomiting immediately or sometime after feeding
• Eating less and vomiting more in general

What are the different types of congenital glaucoma?

Congenital glaucoma is broadly classified into two categories- Primary congenital glaucoma and Secondary congenital glaucoma. They have further subtypes. These are discussed below in details-

Primary congenital glaucoma: Primary congenital glaucoma usually develops after birth. But the manifestations occur as late as in infancy or in early childhood. It arises from some structural defects of the drainage system of the eyes (aqueous outflow system), which leads to an abnormal increase in the pressure inside the eye-chambers. This subsequently leads to a damage of the ocular structures and causes loss of vision. Primary congenital glaucoma is also known as Trabeculodysgenesis. Goniodysgenesis may develop in some infants, the main characteristic of which is ocular hypertension.

 Following are some of the features of primary congenital glaucoma-

• Enlargement of the eyeballs or buphthalmos
• Corneal edema
• Photophobic tendencies
• An overflow of tears (epiphora)
• Optical disc cupping
• Refractive changes (myopia in most cases)
• Cloudy cornea
• High intraocular pressure

Secondary congenital glaucoma: Secondary congenital glaucoma is characterized by Iridocorneotrabeculodysgenesis or Iridotrabeculodysgenesis. In the first case, three main syndromes are commonly observed-

• Axenfeld-Riger syndrome: In this disease, abnormalities in the anterior part of the eyes occur. Many of the patients exhibit corectopia or dislocation of the pupil from the centre. The others exhibit polycoria in which extra holes are present in the iris which looks like multiple pupils.
• Peters plus syndrome: In this disease, structural abnormalities of the anterior segment of the iris are present. These defects lead to an incomplete separation of the cornea from the iris. The patients may also have an opacity of the cornea which usually varies from a tiny dot to a larger area in the central part of the cornea.

Iridotrabeculodysgenesis on the other hand has the following features-

• Stromal defects: The stromal defects mainly include hypoplasia or incomplete development of the optic nerves. Hyperplasia of the retinal pigment epithelium is also observed in many cases.
• Iris vessels abnormalities: Persistent tunica vasculosa lentis is the common congenital anomaly of the iris vessels.
• Structural abnormalities: The major structural defects observed are- holes in the iris, coloboma (defective lens or retina) and aniridia (absence of iris in one or both eyes).

A few other varieties of congenital glaucoma are listed below-

• Pigmentary glaucoma: In this disease, the iris pigments are shed into the aqueous humor. These pigments lead to the clogging of the trabecular meshwork pores, which in turn cause a build-up of intraocular fluid.
• Primitive corneal dystrophies: It is characterised by the degeneration of the endothelial layer of the eyes.
• Megalocornea: In this disease, the intraocular pressure remains normal and the cornea is clear. But an abnormal enlargement of the corneal diameter occurs.

Diagnosis

The following diagnostic tests are necessary-

• Tonometry
• Pachymetry
• Dilated eye examination
• Visual field test
• Visual acuity test

Treatment & Prevention

Surgery is the only way to treat congenital glaucoma. The following types of surgery are performed on patients of congenital glaucoma:

• Goniotomy: In this method, a goniolens is used to visualize an abnormal tissue and perform an incision to release the ocular pressure.  This method falls under the category of internal approach to congenital glaucoma treatment.
• Trabeculotomy: This an external method of congenital glaucoma surgery. In this method, a probe is introduced into the Schlemm canal and is externally dissected.  This can be performed in patients with cloudy corneas.

Both the surgeries guarantee an 80% success rate.  There are no specific ways to prevent the onset of congenital glaucoma, but with early diagnosis, further vision loss can be prevented. Parents should be aware of the tell-tale signs of congenital glaucoma and should immediately seek medical help if the child shows few or all the symptoms. This check becomes more important if there is a family history of congenital glaucoma.

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