[Two rare lens abnormalities in horses].

The research article presents two cases of uncommon lens deformities in horses – coloboma and ectopia. The study details the clinical and ophthalmoscopic features of these lens defects in a young Hanoverian stallion and filly.

Congenital Coloboma of the Lens

• In the first case of a 3-year old Hanoverian stallion, the researchers found a congenital coloboma of the lens. Coloboma is a defect that presents as a hole in the structure of the eye, typically in areas like the iris, retina, choroid, or optic disc.
• The coloboma in this case was associated with a partial coloboma of the zonules, the fibres that hold the lens in place in the eye. As such, the zonules’ partial absence probably contributed to the lens’ abnormal shape.

Ectopic Lens

• The second part of the study reports on an ectopic lens in a 6-month old Hanoverian filly. Ectopia is a medical term used to describe an organ or body part that is located in an unusual place, in this case, the lens.
• This filly’s ectopic lens was also observed to be diminutive and spherical, identified as microphakia (small lens) and spherophakia (spherical lens). This ectopic lens was associated with syneresis i.e., the shrinking and condensation in the vitreous, and presence of small floating particles in the vitreous.
• Although the researchers considered that prenatal uveitis, an inflammation of the middle layer of the eye, might have caused the lens to shift to an ectopic position, they decided to classify it as congenital in this particular case.

Additional Findings

• In both the studied cases, the researchers did not find any other clinically detectable congenital defects. This reaffirms that these are indeed rare abnormalities and they are the primary focus of this article.