Visual field defects in onchocerciasis

Area of Science:

• Ophthalmology
• Tropical Medicine
• Parasitology

Background:

• Onchocerciasis, a parasitic disease, can affect the posterior segment of the eye.
• Previous research has not extensively detailed the functional visual loss caused by these ocular lesions.

Purpose of the Study:

• To investigate and characterize visual field defects in patients with onchocerciasis.
• To determine the extent of functional visual loss associated with posterior segment ocular lesions in onchocerciasis.

Main Methods:

• Examination of visual fields using a tangent screen test.
• Study included 18 selected cases of onchocerciasis with posterior segment ocular lesions.

Main Results:

• Significant visual field defects were observed in all cases.
• Optic nerve involvement was a key factor, leading to severely constricted visual fields.
• Postneuritic optic atrophy and papillitis resulted in almost complete visual field constriction, sparing only a small central area (5-10 degrees).

Conclusions:

• The pattern of visual field defects suggests progressive optic nerve lesions from the periphery contribute to vision loss in onchocerciasis.
• Visual field deficits in onchocerciasis represent a significant handicap with considerable socioeconomic implications.