Phenylephrine eyedrops as a diagnostic test in equine grass sickness.

This research study sought to explore the effects of administering phenylephrine eyedrops in horses diagnosed with grass sickness by observing changes in the size of the palpebral fissure.

Objective of the Study

In this research, the aim was to examine the impact of administering phenylephrine, an alpha-1 adrenergic agonist, as eyedrops in horses diagnosed with a condition known as grass sickness.

Methodology

• The research was conducted on two sets of horses: one consisting of 23 cases suffering from grass sickness, and a control group of 12 healthy horses.
• Both groups were administered ocular phenylephrine.
• The scientists focused on the alteration in the size of the palpebral fissure (the opening between the eyelids) following the administration of the drops. In particular, they studied the change in the angle of the eyelashes to the head as observed from a frontal view, which indicated the change in the size of the fissure.

Findings

• The researchers discovered that the mean increase in the size of the palpebral fissure was more significantly prevalent in the horses suffering from grass sickness than in the control group.
• This observation suggests that phenylephrine eyedrops can cause changes in the eye presentation of horses with grass sickness.

Conclusion

The research indicates that ocular administration of phenylephrine may provide a diagnostic tool in assessing the presence of grass sickness in horses. The response to the eyedrops, as indicated by the change in the size of the palpebral fissure, could serve as an observable physical marker for the illness.