Infection of the cornea in fishes by Myxobolus plasmodia is a common but still little known site preference of myxosporeans. A sporadic but striking infection in the cornea of the roach (Rutilus rutilus) was observed in Lake Balaton, Hungary. Relatively small, round plasmodia 250 to 500 μm in diameter developed in the dense connective tissue of the cornea. Morphological and molecular biological examination of spores collected from cysts in the cornea demonstrated that this infection is caused by Myxobolus fundamentalis, a species hitherto reported only from the cartilaginous gill arch of the roach. The 18S rDNA sequences of spores from the cornea showed 99.9% identity to the sequences of spores from the gill arch, and they also shared 99.9% identity with the sequences of triactinomyxon actinospores obtained from the oligochaete Isochaetides michaelseni.
Kaifi JT, Diaconu E, Pearlman E: Distinct roles for PECAM-1, ICAM-1, and VCAM-1 in recruitment of neutrophils and eosinophils to the cornea in ocular onchocerciasis (river blindness). J Immunol 166, 6795–6801 (2001
For the perfect image a healthy tear film, transparency of the cornea, aqueous humour, the crystalline lens, the vitreous body are needed, as well as a perfect structure of the multilayer retina and the neuronal system (optic pathway