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Primary congenital glaucoma: causes, symptoms, diagnosis, treatment
Last reviewed: 04.07.2025
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Congenital glaucoma is a group of conditions with abnormalities in the development of the aqueous humor outflow system. This group includes: congenital glaucoma, in which the abnormal development of the anterior chamber angle is not associated with other ocular or systemic abnormalities; congenital glaucoma with associated ocular or systemic abnormalities; secondary childhood glaucoma, in which other ocular pathologies cause impaired fluid outflow.
There are several different approaches to classifying congenital glaucomas. The most commonly used anatomical classifications are those of Schaeffer-Weiss and Hoskin. The Schaeffer-Weiss classification distinguishes three main groups: primary congenital glaucoma; glaucoma associated with congenital anomalies; and secondary glaucomas of childhood. The second classification is based on developmental anomalies determined clinically during examination and also includes three groups: isolated developmental disorder of the trabecular apparatus with malformation of the trabecular meshwork without anomalies of the iris and cornea; iridotrabecular dysgenesis, including anomalies of the angle and iris; corneal trabecular dysgenesis, often associated with anomalies of the iris. Determination of anatomical defects can be useful for determining treatment tactics and prognosis.
Primary congenital glaucoma is the most common form of childhood glaucoma, accounting for approximately 50% of all cases of congenital glaucoma. It is characterized by abnormalities in the development of the trabecular meshwork and no association with other eye or systemic diseases. In 75% of cases, primary congenital glaucoma affects both eyes. The incidence is 1 in 5,000-10,000 live births. More than 80% of cases occur before the age of 1 year: 40% immediately after birth, 70% between 1 and 6 months, and 80% before 1 year. The pathology is more common in boys (70% in boys and 30% in girls); 90% of cases are sporadic and there is no family history. Despite the development of an autosomal recessive model with variable penetrance, most cases are thought to result from multifactorial inheritance involving non-genetic factors (eg, environmental factors).
[ Symptoms of Primary Congenital Glaucoma
Anamnesis
Lacrimation, photophobia, and blepharospasm form a classic triad. Children with congenital glaucoma usually prefer semi-darkness and avoid bright light. Excessive lacrimation is noted. In the case of unilateral damage, the mother may notice asymmetry of the child's eyes, an increase (affected side) or decrease (normal side) in the size of the eyes.
External examination
The normal horizontal corneal diameter in full-term newborns is 10-10.5 mm. It increases to adult size (approximately 11.5-12 mm) by two years. A corneal diameter of more than 12 mm in a newborn indicates a high probability of congenital glaucoma.
Corneal opacities, ruptures of Descemet's membrane (Haab's striae), deep anterior chamber, intraocular pressure greater than 21 mm Hg, iris stromal hypoplasia, isolated trabeculodysgenesis on gonioscopy, and increased optic disc excavation may also be detected. Haab's striae may be single or multiple and are usually oriented horizontally or concentrically to the limbus.
Evaluation of the optic disc is a key point in diagnosing glaucoma. Glaucomatous changes in the disc occur faster in infants and against the background of lower intraocular pressure than in adolescents and adults. The ratio of the excavation area to the optic disc area of more than 0.3 is rarely seen in infants and indicates a high probability of developing glaucoma. The same is indicated by asymmetry of the excavations of the discs, especially a difference of more than 0.2 between the two eyes. The glaucomatous excavation can be oval in shape, but more often it is round, located in the center. After normalization of the intraocular pressure, the excavation returns to its original state.
To make an accurate diagnosis and prescribe adequate treatment, it is necessary to evaluate the anterior chamber angle of the eye. Developmental anomalies can be present in two main forms: flat iris attachment, in which the iris is attached directly or anterior to the trabecular meshwork, with its processes possibly extending over the scleral spur, and convex iris attachment, in which the iris is visible behind the trabecular meshwork but is covered by dense abnormal tissue. A photograph of a gonioscopic picture of a normal anterior chamber angle in an infant is also provided for comparison.
An increase in intraocular pressure causes the eyeball to greatly enlarge with progressive thickening of the cornea in children under 3 years of age. As the cornea enlarges, its stretching leads to ruptures of the Descemet membrane, edema of the epithelium and stroma, and corneal opacity. Stretching of the iris causes the stroma to thin. The scleral canal through which the optic nerve passes also enlarges with an increase in intraocular pressure, leading to a rapid increase in the optic disc excavation, which quickly returns to its original state when the intraocular pressure returns to normal. Such a rapid restoration of the excavation size does not occur in adults, probably due to the greater elasticity of the connective tissue of the optic nerve papilla in infants. If intraocular pressure cannot be controlled, buphthalmos may develop.
Differential diagnosis of primary congenital glaucoma
Corneal changes also include megalocornea, metabolic diseases, corneal dystrophies, birth trauma, and keratitis. Lacrimation or photophobia may occur with nasolacrimal duct obstruction, dacryocystitis, and iritis. Optic nerve changes similar to those seen in glaucoma include optic disc pits, colobomas, and hypoplasia.
Treatment of primary congenital glaucoma
Congenital glaucoma is always treated surgically. Drug therapy can be used for a limited period of time - until surgery is prescribed. The method of choice in such conditions is trabecular incisions. Goniotomy requires a transparent cornea to visualize the anterior chamber angle. Goniotomy is performed using a goniotome and a straight goniolens, preferably a Barkan goniolens. Using a goniotome, an incision is made in dense abnormal tissue on the trabecular meshwork over a length of 90 to 180° through the transparent cornea (Figs. 10-7 and 10-8). Trabeculotomy with external access to the Schlemm's canal does not require corneal transparency.
Trabeculotomy is indicated when the cornea is cloudy. A scleral flap is created in which the Schlemm canal must be identified for the procedure. The trabecular meshwork is cut using a trabeculotome or using a suture (usually propylene) passed through the Schlemm canal (Lynch method). If the Schlemm canal cannot be identified, a trabeculectomy is performed. Another treatment option for such patients is the installation of valved or valveless drainage devices.