Juvenile Glaucoma

A primary early-onset glaucoma that is characterized by early onset, severe elevation of intra ocular pressure of rapid progression, leading to optic nerve excavation and, when untreated, substantial visual impairment.

Epidemiology

The disorder is estimated to occur in 0,32/100 000 individuals before the age of 20 years.

Clinical description

Juvenile glaucoma (JG) typically presents between the ages of 5 to 18 years, but it can appear later. Patients are initially asymptomatic and are often discovered incidentally on a routine examination. JG is generally bilateral; there can be a marked asymmetry between the two eyes. The intraocular pressure increases progressively leading to optic nerve excavation and eventually, substantial visual impairment and field loss.

Etiology

JG is caused by impaired outflow of aqueous humor through the trabecular meshwork and into the Schlemm canal. Mutation in MYOC (1q23-q24) genes have been found in patients with JG. MYOC gene codes for the glycoprotein myocilin that is found in the trabecular meshwork and ocular tissue and mutations are disease-causing.

Diagnostic methods

The diagnosis is suspected with the presence of clinical features such as increased intraocular pressure and optic nerve excavation. On gonioscopy the angle appears normal. Typical features of primary congenital glaucoma such as corneal edema and Haab's striae are not present. The refraction test reveals myopia. Typical glaucomatous field defects can be documented. Optic nerve head shows glaucomatous optic neuropathy.

Differential diagnosis

Differential diagnoses include other forms of open angle glaucoma that can occur at any age, late recognized congenital glaucoma, steroid induced glaucoma, traumatic glaucoma and inflammatory glaucoma.

Genetic counseling

Transmission is autosomal dominant with high penetrance. Genetic testing can be used to identify family members at risk of developing JG. Genetic counseling should be proposed to individuals having the disease-causing mutation informing them that there is 50% risk of passing the mutation to offspring.

Management and treatment

Medical therapy (carbonic anhydrase inhibitors, beta blockers, prostaglandin analogues) is often useful in the treatment of JG. When the condition becomes unresponsive to medications, angle surgery (goniotomy, trabeculotomy), filtration surgery (trabeculectomy), LASER treatment (angle laser surgery or cyclodiode laser therapy) and/or aqueous shunt devices can be considered.

Prognosis

Prognosis is good in patients diagnosed and treated early. Without treatment, the evolution towards blindness is possible.