Leprosy.—The eye is more frequently involved in nodular than in nerve leprosy. In the former we have infiltration of the conjunctiva which may extend to the cornea.
The leprous nodules invading the palpebral conjunctiva tend to ulcerate and bring about various distortions of the eyelids, producing ectropion. Iritis, irido-cyclitis and irido-choroiditis are less frequent than conjunctivitis and keratitis. The optic nerve and the retina are only rarely involved.
In nerve leprosy the eye changes are chiefly connected with the lesions of the fifth and facial nerves. Ptosis and paralytic ectropion occur with frequency.
Ophthalmia and corneal ulcerations may lead to total destruction of the eye. The cornea may be anaesthetic. Paralysis of one or more ocular muscles may cause squint or diplopia.
Malaria.—It is questionable whether the forms of conjunctivitis and keratitis at times reported as due to malarial infection are not rather of other origin.
Iritis is rarely a complication of malaria.
Retinal haemorrhages may occur in malarial cachexia and cerebral types of pernicious malaria.
Another rare malarial complication is amblyopia. In this there is an optic neuritis with grayish-red disc and the loss of vision is not complete, while in quinine amblyopia the disc is white and the vision completely lost for a time.
Filariasis.—In that filarial infection caused by Loa loa, at one time designated Filaria oculi, there seems a special tendency for the adult worms to wander to the subcutaneous tissues in the neighborhood of the eyes or under the palpebral or ocular conjunctivae. When moving under the conjunctiva the worms cause marked irritation and at times pain.