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EQUINE VETERINARY EDUCATION / AE / MAY 2015
Fig 1: Ultrasonographic image (9 MHz) of the right eye (a: anterior lens capsule; b: posterior lens capsule), presenting a hypoechoic structure surrounded by a thin hyperechoic wall, lying posterior to the temporal iris, compatible with a temporal ciliary cyst (arrow).
probe, using a transpalpebral method without standoff pad (Gilger and Stoppini 2011). The sagittal plane of the left and right eyes measured 44 and 46 mm, respectively, which was considered normal for this horse. In both eyes, but more pronounced in the right eye, temporal ciliary cysts were seen as hypoechoic structures surrounded by a thin hyperechoic wall, lying posterior to the temporal iris (Fig 1). No obvious indications of retinal detachment or cataract were observed.
Treatment
A subpalpebral eye lavage system7 was used to medicate the right eye every 2 h with a mixture of hypertonic saline (NaCl 5%), nonsteroidal anti-inflammatory medication (ketorolac trometamol, Aculare 0.5%)8, artificial tears (Isopto Tears)9 and acetylcysteine (Lysomucil 10%)10, alternated with the administration of autologous serum. Oral treatment with flunixin meglumine 5% w/w (Finadyne oral paste)11 was instituted. No improvement was seen after 9 days. Based on the lack of response to treatment and the poor
long-term prognosis, the owner decided to have the mare subjected to euthanasia.
Magnetic resonance imaging
Immediately after euthanasia, the head was separated from the rest of the body through the atlanto-occipital joint; subsequently, after disarticulating the temporomandibular joint, the mandibula was removed. Magnetic resonance imaging was performed on the horse’s head using a low field magnet (0.2 Tesla scanner; Airis Mate)12. Images were obtained in 3 planes (sagittal, transverse and dorsal) with 4mm slice thickness. Sequences included T1-weighted (T1W), T2-weighted (T2W), spin echo (SE), short T1 inversion recovery (STIR) and fluid attenuation inversion recovery (FLAIR). More prominently present in the right than in the left eye,
the ciliary body showed an abnormal, slightly hyperintense signal and seemed irregular and dilated on T1W (SE) images with an enlarged and iso- to hypointense appearance in the centre on FLAIR (Fig 2). The surface of the right cornea was irregular and flattened on T1W (SE) images (Fig 3) with a
© 2015 EVJ Ltd
Fig 3: Transverse T1-weighted image at the level of the right eye. There is flattening and an irregularity of the cornea (arrow).
hyperintense pocket on T2W (SE) sequences (Fig 4). The periocular structures including the optic nerves showed a normal appearance.
Necropsy and histological findings
After euthanasia and MRI, a necropsy was performed on the horse, during which both globes were enucleated, fixed in 10% neutral buffered formalin and embedded in paraffin. Sections of 5 μm thick were mounted onto glass slides and stained with haematoxylin and eosin for microscopic examination. Grossly, both eyes appeared enlarged with a pronounced
protruding cornea (Fig 5), which was more severe in the right eye.
Fig 2: Transverse FLAIR image at the level of the right eye, showing a dilated ciliary body with a hypointense centre, compatible with a cystic lesion (arrow).
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