Which species has the higher typical normal intraocular pressure range?

• A. Dogs and cats
• B. Horses
• C. Both have the same
• D. Rabbits

Answer: (B)

Normal intraocular pressure varies between species because it depends on how much aqueous humor is produced and how readily it drains, along with differences in eye size and tissue properties. Horses tend to have higher baseline IOP values than small animals like dogs and cats, and than rabbits, due to their larger globe, greater episcleral venous pressure, and distinct corneal and scleral characteristics. Measurement technique and diurnal fluctuations can also influence readings, but, on average, horses sit higher on the normal scale. So, the species with the higher typical normal intraocular pressure range is the horse.