Aqueous drainage paths in the equine eye: scanning electron microscopy of corrosion cast.

The research involves examining the front part of a horse’s eye using a process called corrosion casting. The study found that the horse’s eye has a blood vessel design that is similar yet different from other mammals. These findings are significant in understanding and treating recurring inflammation in horses’ eyes and other diseases affecting the back part of the eye.

Study Methodology

• The researchers used corrosion casting to examine the anterior vasculature (blood vessels in the front part of the eye) in a pony’s eye. This technique involves injecting a resin into the vascular system, allowing it to harden, and then removing the surrounding tissues, leaving a detailed 3D cast of the vasculature.
• This allowed the researchers to observe and compare the vascular pattern of the pony’s eye with that of other mammalian species.

Findings

• Large iridal veins in the pony’s eye were found to directly collateralize (form a network) with the anterior vortex venous system, which is a system of small veins within the eye.
• An intrascleral plexus, a network of veins within the sclera or white part of the eye, was present, forming a fine, extensive network oriented radially (emerging from a common center).
• This design was in contrast to the larger, circumferential intrascleral plexus found in dogs and the canal of Schlemm found in primates.
• The intrascleral plexus in the pony’s eye was found to only drain towards the back. This is in contrast to other species, where anterior collateralizations (networks towards the front of the eye) have been documented.

Clinical Relevance

• This pattern of aqueous outflow (movement of fluid in the eye) holds clinical relevance in veterinary medicine, particularly for the treatment of equine recurrent uveitis, a common and painful eye inflammation in horses. Understanding these unique drainage patterns could lead to improved treatment strategies.
• The findings may also provide insight into diseases affecting the posterior segment, or back of the eye, in horses and potentially in other species.