Tips and Tricks: The examination

Observation before interaction better indicates the severity of ocular pain, whether the contralateral eye is also involved, and whether sedation will be required.

The eyelid is most easily displaced by gently applying the fingertips within 3-5mm of the margin and lifting upwards and outwards. Pulling the dorsal skin upwards is less effective because the free eyelid will still droop.

Closer examination of the eyelid, cornea and anterior chamber may be achieved readily using an otoscope head if a Finoff transilluminator is not available.

Administration of topical solutions is readily achieved by dispensing into a 1 or 3 mL syringe attached to the hub of a 25- or 27-gauge hypodermic needle. The needle is readily removed by bending it 90 degrees, and then 180 degrees in the opposite direction. The globe is protected from the syringe and hub by concealing it along one finger and into the palm of the hand.

Horses dislike their eyelids being touched. Examine what you can before you touch the face. When the eyelids must be held, allow a few moments for the patient to settle again proceeding.

Rolling the poll toward you (and the nose away) will expose the ventral cornea and sclera readily if the vestibular system is functional. The head should still point forward and not be turned to the shoulder.

Normal extraocular muscle function (or globe entrapment) can be evaluated by turning the head alternately from side to side and finally rotating it to initiate normal vestibulo-ocular nystagmus.

Pupil symmetry can be evaluated from 10 feet in front of the horse in a darkened environment using a direct ophthalmoscope.

Sudden motion by the patient can be counteracted by lightly resting one hand on the skull and bracing the instrument against the arm so the head motion will be transferred seamlessly to the examiner, avoiding sudden contact and injury.

Consensual PLRs can be evaluated by swinging a bright light from eye to eye, evaluating for inappropriate dilation in a damaged globe. Alternatively, an assistant can shine light in the tested eye while the examiner monitors the contralateral pupil by indirect illumination.