Ivermectin for onchocercal eye disease (river blindness).

Area of Science:

• Ophthalmology
• Infectious Diseases
• Tropical Medicine

Background:

• Onchocerciasis, a parasitic infection, is a leading cause of preventable blindness.
• Ivermectin is a microfilaricide used to treat onchocerciasis, but its impact on ocular lesions and visual loss is not fully understood.
• Community-wide ivermectin distribution aims to control onchocerciasis, yet its effectiveness in preventing eye disease progression requires clarification.

Purpose of the Study:

• To evaluate the efficacy of ivermectin in preventing visual impairment and visual field loss in patients with onchocercal eye disease.
• To assess the impact of ivermectin on ocular lesions associated with onchocerciasis.

Main Methods:

• Systematic review of randomized controlled trials (RCTs) with at least one year of follow-up.
• Searched multiple databases including CENTRAL, MEDLINE, EMBASE, mRCT, ClinicalTrials.gov, and WHO ICTRP.
• Included trials comparing ivermectin with placebo or no treatment in individuals from onchocerciasis-endemic communities.

Main Results:

• Four trials were included: two small individual RCTs and two large community-based studies.
• Ivermectin treatment reduced ocular microfilariae and punctate opacities.
• Evidence suggests ivermectin may reduce chorioretinitis and, in specific settings (savannah strain), optic nerve disease and visual field loss.
• Studies were underpowered to definitively assess effects on visual impairment, sclerosing keratitis, iridocyclitis, or optic nerve disease.

Conclusions:

• While ivermectin reduces microfilarial load and some ocular lesions, definitive evidence for preventing visual impairment and blindness is lacking.
• Mass ivermectin treatment shows promise in preventing visual field loss and optic nerve disease in communities with the savannah strain of O. volvulus.
• Further research is needed to clarify ivermectin's role in preventing visual loss across diverse onchocerciasis endemicities and parasite strains.