Environmental factors such as living arrangements and stress have the potential to cause ophthalmic disease in horses. In a recent study, researchers in Turkey examined and compared intraocular pressure (IOP) and tear production in horses living in stables versus medical barns to determine whether different settings—familiar vs. unfamiliar—affected their ocular health.
Study on IOP and Tear Production in Horses
The study involved 30 healthy Arabian horses with no existing ocular disorders. The horses were split into two groups: 15 in the medical barn and 15 in the horse stable. Both stabling environments had identical light, temperature, and humidity conditions. The researchers measured the horses’ intraocular pressure and tear production in each group, then swapped the horses between facilities for a second visit sampling.
They took measurements without using sedation or local or topical anesthesia. A tonometer was used for IOP measurements. A Schirmer tear test strip was used for tear production measurement five minutes after the researchers obtained IOP values. They found that:
- IOP mean value was 29.5 mmHg in the horse stable and 34.2 mmHg in the medical barn.
- Tear production averaged around 22 mm/min in both eyes in the horse stable and ranged between 23 and 24 mm/min for left and right eyes in the medical barn.
Conclusions
The authors noted that while the IOP in the medical barn was significantly higher (+ 4.7 mmHg) than in the horse stable, “variation of less than 5 mmHg is unlikely to be clinically relevant.” The difference in IOP between medical barn and horse stable might reflect some degree of stress the horses experienced in an unfamiliar environment. The researchers found no significant difference in tear production between environments; these measurements are comparable to other studies on normal tear production values. Stress might not influence tear production like it does intraocular pressure.
Reference
Cinar H, Yanmaz LE, Buyukkaraca N. Comparing the effects of intraocular pressure and tear production measurements in horses in two different environments: Horse stable and medical barn. Equine Veterinary Journal Jan 2024; DOI: 10.1111/evj.14067
