Which test is the most effective for diagnosing congenital glaucoma?

Tonometry is the most effective test for diagnosing congenital glaucoma because it measures intraocular pressure (IOP), which is often elevated in individuals with this condition. Congenital glaucoma is characterized by abnormalities in the eye's drainage system, leading to increased pressure that can damage the optic nerve and affect vision. Early detection through IOP measurement is critical to prevent irreversible damage and preserve visual function.

Fluorescein staining is primarily used to assess for corneal abrasions or other ocular surface issues rather than to measure pressure in the eye. The Snellen vision exam assesses visual acuity, which may be affected by glaucoma but does not specifically diagnose the condition itself. Evaluating the refractive index is not a standard method for diagnosing glaucoma; rather, it is more related to assessing the lens or refractive errors in the eye.

Given the specific nature of congenital glaucoma and its symptoms, tonometry stands out as the essential diagnostic tool for monitoring and identifying aggressive intraocular pressure changes that can lead to significant complications if not addressed.