Family screening for glaucoma

Glaucoma constitutes an important cause for irreversible blindness, mostly due to obstruction of intraocular aqueous outflow passage resulting in raised intraocular pressure and optic nerve damage.

This is predominantly seen in two forms in adults, namely, open and closed angle glaucoma, referring to the anatomic configuration of the inside of the eye which defines the mechanism of outflow obstruction.

It is important to understand that glaucoma does not affect only individuals but also families. Various landmark trials have established the importance of early diagnosis
and control in preventing glaucomatous damage.

Glaucoma in younger individuals termed as ‘Juvenile Open Angle Glaucoma’ is also known to be hereditary. Hence siblings and other family members need to be screened for glaucoma.

So screening of family members is of utmost importance in early diagnosis of glaucoma in first-degree relatives to avoid preventable blindness. There is a strong familial inheritance of childhood glaucoma and the prevalence is very high among communities where consanguineous marriages are accepted socially, as seen in many parts of southern India.

Hence screening of children is mandatory in such families. Also genetic counseling and planning the family helps in preventing this serious disease.

Who should be screened?

All first-degree relatives, parents, siblings, children should undergo detailed ophthalmological examination atleast once with specific emphasis on diagnosing glaucoma. While family history of glaucoma is a definite risk factor for adult glaucoma, similar risk holds true for another child if one child has glaucoma at birth or at 3 years (congenital or developmental glaucoma) or between 3-25 years (juvenile open angle glaucoma) of age. So screening of children along with genetic counseling of parents is essential for those with one or more children with glaucoma in the family.

When should they be screened?

While there is no set age at which screening should start, all patients should have their eyes tested atleast once beyond the age of 40 years if they have a family history of glaucoma. Children may also be screened at any age to rule out juvenile onset glaucoma or diagnosing steroid responders which are common in family members of patients with POAG.

What if they have glaucoma?

Various studies have established that early intervention can help prevent blindness and long term progression of glaucoma. So early diagnosis is a key for initiating early treatment which goes a long way in preventing further damage.

What if they are normal?

A normal examination at baseline does not rule out glaucoma and periodic screening at least yearly in all family members. Such evaluations would include IOP assessment, gonioscopy and fundus evaluation. There is no cut-off age beyond which screening should be stopped and risk can be deemed to be absent in a particular individual.

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