What is the normal intraocular pressure range in horses?

What is the normal intraocular pressure range in horses?

• A. 15 to 30 (37) mmHg
• B. 5 to 15
• C. 40 to 60
• D. 10 to 20

Answer: (A)

Normal intraocular pressure in horses sits in a relatively wide range, commonly about 15–30 mmHg. In healthy eyes, values can occasionally reach the mid‑30s (up to around 37 mmHg) depending on the tonometry method used and diurnal variation. This range reflects the balance between aqueous humor production and outflow plus episcleral venous pressure in equine eyes, and it accommodates measurement differences between devices like applanation, rebound, or indentation tonometers. If IOP is consistently higher than the upper end (for example above ~30–35 mmHg), that raises concern for ocular hypertension or glaucoma. If it’s significantly below the lower end (below ~10–12 mmHg), that suggests hypotony and potential severe inflammation or other pathology. The other ranges don’t fit because 5–15 mmHg would indicate hypotony, 40–60 mmHg is well into a glaucomatous or dangerously elevated range, and 10–20 mmHg omits the higher values that can still be normal in horses.

Normal intraocular pressure in horses sits in a relatively wide range, commonly about 15–30 mmHg. In healthy eyes, values can occasionally reach the mid‑30s (up to around 37 mmHg) depending on the tonometry method used and diurnal variation. This range reflects the balance between aqueous humor production and outflow plus episcleral venous pressure in equine eyes, and it accommodates measurement differences between devices like applanation, rebound, or indentation tonometers.

If IOP is consistently higher than the upper end (for example above ~30–35 mmHg), that raises concern for ocular hypertension or glaucoma. If it’s significantly below the lower end (below ~10–12 mmHg), that suggests hypotony and potential severe inflammation or other pathology.

The other ranges don’t fit because 5–15 mmHg would indicate hypotony, 40–60 mmHg is well into a glaucomatous or dangerously elevated range, and 10–20 mmHg omits the higher values that can still be normal in horses.