The paper discusses an evaluation of an eye mass in a 5-year-old horse over a course of five months, using various diagnostic tools and methods in veterinary ophthalmology. Tests and examinations found no abnormal results, and the mass appears to be confined to the eye’s nictitating membrane.

Case Study and Examination

• This article presents a case study where a 5-year-old Belgian gelding (a male horse that has been castrated) was brought to the Western College of Veterinary Medicine with an issue related to its right eye. A growth, resembling a mass, on the third eyelid had been increasing in size throughout the span of 5 months.
• The horse was evaluated through a series of standard eye reflex tests, all of which it passed. These tests included the “menace response” (a defensive blinking reflex), palpabrel a blink reflex stimulated upon touching the eyelashes, oculocephalic reflex, the movement of the eyes dependent on the movement of the head and light reflex tests – both direct and consensual (shared response between both eyes).

Diagnostic Tools and Results

• Using Schirmer tear test strips, it was found that the tear production in both eyes was at a suitable level of 20 mm/min.
• The intraocular pressures of the horse were also checked with a rebound tonometer and recorded as 16 mmHg in both eyes. The values fall within the normal range, thus suggesting the horse was not suffering from glaucoma.
• Negative results from a fluorescein staining test, performed bilaterally, confirmed that there was no corneal damage or ulcers on the surface of the horse’s eyes.

Further Examination Details

• Upon close examination, the mass was a 2.5cm × 2cm sized raised, irregular, pink tissue found on the nictitating membrane (or third eyelid). Only the right eye had mucoid discharge present at the medial canthus (corner of the eye where the upper and lower eyelids meet).
• After the application of a dilation solution (tropicamide), the pupils of the horse were dilated for further examination. Detailed assessments using a biomicroscope and indirect ophthalmoscope revealed that the mass was confined to the conjunctiva of the nictitating membrane – meaning it did not extend beyond the membrane – and could potentially be less harmful. No other abnormalities were observed.