WHAT IS HYPERTENSIVE RETINOPATHY?
Hypertensive Retinopathy is a disease of the retina that is caused by an abnormally high blood pressure (systemic hypertension). Hypertension can cause damage of small retinal blood vessels. This damage can lead to leakage of serum and blood. The leakage of these vessels results in accumulation of fluid underneath the neuro-retina and is visualized as an out-pouching of the retina, termed serous retinal detachment. When detached, the retina is unable to generate a clear, concise picture from the incoming rays of light causing vision to become distorted and dim. Blood vessels also have the potential to rupture with increased pressure, therefore causing bleeding within the eye.
The two primary diseases feline hypertension is commonly associated with are hyperthyroidism and kidney disease. These two diseases are among some of the most prevalent diseases seen in geriatric felines.
WHAT ARE THE SIGNS OF HYPERTENSIVE RETINOPATHY?
Typically older animals are affected. You may notice a redness of the eyes, big pupils and decreased vision. Acute blindness is the most common clinical manifestation of systemic hypertension in cats. Some cats have blood in the front part of the eye. Some animals show weightloss, drink more and are apathic, while others feel normal.
HOW IS HYPERTENSIVE RETINOPATHY DIAGNOSED?
Performing an ophthalmic examination as well as evaluating systemic blood pressure, is useful in diagnosing hypertensive retinopathy. The normal systolic blood pressure for an adult cat is measured between 100 and 160 mmHg, therefore systemic hypertension in the feline is defined as a sustained elevation of systolic pressure greater than 170 mmHg. Ophthalmic examination is necessary to determine the integrity of the retina and its associated vessels as well as to evaluate the pupillary light response. Tonometry, the assessment of intraocular pressure, is also helpful, to determine if the intraocular pressure is elevated in cases of intraocular bleeding.
WHAT IS THE TREATMENT FOR HYPERTENSIVE RETINOPATHY?
Because untreated hypertension may result in serious neurologic, ocular, renal, and cardiac disease, treatment of cats with this disorder is imperative. Vision loss due to retinal detachment occurs abruptly and requires immediate attention in order to preserve some retinal function and allow for the possibility of retinal reattachment. A common anti-hypertensive drug prescribed is Amlodipine. Long-term anti-hypertensive therapy may be required depending on the underlying condition that caused the hypertension.
WHAT ELSE SHOULD BE DONE FOR PETS WITH HYPERTENSIVE RETINOPATHY?
It is important to have your cats eyes examined regularly in order to evaluate if the retinal changes have improved or if new bleedings occurred, which is an indicator that the systemic blood pressure control still needs to be adjusted. Repeated measurements of the systemic blood pressure is also important. Bloodwork to evaluate renal and thyroid function and possibly a cardiology consult is recommended.