Aspects of corneal changes in onchocerciasis

Area of Science:

• Ophthalmology
• Parasitology
• Medical Entomology

Background:

• Ocular onchocerciasis is a significant cause of blindness in endemic regions.
• Understanding microfilariae distribution is crucial for diagnosing and managing the disease.

Purpose of the Study:

• To investigate the distribution patterns of living and dead microfilariae in the cornea.
• To correlate microfilariae density with corneal opacities and sclerosing keratitis.
• To analyze the influence of microfilariae and inflammation on corneal thickness.

Main Methods:

• Studied 160 cases of ocular onchocerciasis.
• Utilized a model to code microfilariae densities in nine corneal areas.
• Assessed microfilariae and punctate opacity counts per square millimeter.
• Measured corneal thickness and recorded sclerosing keratitis.

Main Results:

• Highest microfilariae densities were observed in the superficial corneal stroma, peripherally in nasal and temporal regions.
• Sclerosing keratitis patients were significantly older than those without it.
• Corneal thickness was not affected by microfilariae, punctate opacities, or mild uveitis, but varied with vascularization in sclerosed areas.

Conclusions:

• Microfilariae distribution suggests specific entry routes into the ocular tissues.
• Age is a factor in the development of sclerosing keratitis in onchocerciasis.
• Corneal thickness is a complex parameter influenced by inflammation and vascularization in advanced cases.