Our hospital owns a Tonopen, the device used to measure intraocular pressure (IOP). Routine monitoring of IOP during your older pet’s annual or biannual exam is an important step in catching glaucoma early. The Tonopen measurement is fast and comfortable for your pet and can be performed in the exam room.
Glaucoma is a disease in which pressure within the eyeball increases to dangerous levels. It is one of the most common causes of blindness in dogs and cats. Maintenance of normal pressure within the eye depends on a delicate balance between production and escape of internal eye fluid ( aqueous humor). If fluid flow is blocked, internal eye pressure may rise to dangerous levels ( glaucoma) that can permanently destroy the retina and injure other vital structures of the eye. The eyeball may become enlarged if glaucoma persists over a long enough time.
Causes of glaucoma include blockage of the drainage passage due to birth defects, inflammatory conditions, injuries, tumors, concommitttent diseases such as kidney problems and hyperthyroidism, and lens disorders. If primary glaucoma ( not from injury or infection) occurs in one eye, chances are increased that it will occur in the opposite eye.
Clinical signs are very sudden. The eye becomes protruding and very red. The animal is usually in pain. Glaucoma requires prompt visit to the veterinarian or the Emergency Clinic. It is an emergency! The diagnostic is made by taking the intraocular pressure by an instrument called Tonopen and by a detailed exam of the eye. Treatment should be instilled immediately to avoid blindness and the primary cause of the glaucoma should be determined. General chemistry and a complete blood count are done; this will check kidney function as well as many other body systems. Thyroid function should also be tested. Other blood tests might be required for further investigation. Treating the primary cause may take care of the glaucoma.
Treatments vary according of the cause, the severity and the duration time of the condition. Special eye drops will help in controlling the eye pressure. If medical treatment is not satisfactory and the damage to the eye is irreversible, surgery might be needed. Enucleation or insertion of a prosthesis are the available options. After initial medical or surgical treatment, the animal will require continuous medical treatment and close monitoring of both eyes or the remaining one.