LOOKING BEYOND THE EYE – EYE AND SYSTEMIC DISEASE
Dr Madhavi Latha, Consultant, Comprehensive Ophthalmology and Cornea & Anterior Segment Services, L V Prasad Eye Institute.
The eye is composed of different types of tissues, this unique feature makes the eye susceptible to a wide variety of diseases and provides insights into many systemic problems. Almost any part of the eye can give important clues to the diagnosis of systemic diseases which may be evident on a routine eye examination.
Problems in the eye may be the first presentation of a systemic problem or on the other hand patients with known systemic problems need regular comprehensive eye examination for complications that may affect and damage vision.
Common systemic problems and their association with the eye -
Every diabetic should have their eyes examined on diagnosis and annually thereafter.
The underlying cause of diabetic retinopathy is microvascular leakage leading to exudation which occurs in the layers of retina affecting vision. Excess glucose interferes with normal metabolism of the lens and result in premature cataracts.
Depending upon the stage of retinopathy and level of cataract ophthalmologist may advise laser treatment or surgery along with strict control of blood sugar levels and regular eye checkup at specified intervals.
Hypertension may produce no abnormalities if detected early but assessment of fundus is essential to detect such changes.
Hypertensive retinopathy ranges from grade 1 to grade 4, grade 4 being severe form called malignant hypertensive retinopathy. The retinal changes and swelling of the optic nerve resulting in vision loss is associated with a systolic pressure of > 220 mm Hg and a diastolic pressure of >110mm Hg.
Treatment for hypertension may result in resolution of retinal signs if left unattended for too long. Permanent damage to vision may occur because of optic nerve and retinal circulation being affected by hypertension.
Both diabetes and hypertension may also affect nerves of the eye leading to muscle paralysis causing squint, double vision,etc.
Excessive thyroid levels may cause protruding eyes, limitation of eye movements, double vision and corneal disease due to exposure and dryness. In severe form, the optic nerve may get damaged resulting in permanent loss of vision. Symptoms in the eye may appear before any other systemic features.
Cancer can start in the eye or spread from anywhere in the body. Cancer can occur in any part of the eye and depending upon its location it may or may not affect vision. It especially holds true in children who can have cancer called retinoblastoma. The cancer may be evident as a white reflex, squint, recurrent redness, vision loss and in advanced cases may threaten life. So, early detection and timely treatment may be both vision saving and lifesaving.
Conditions like anaemia, platelet disorders - polycythaemia, haemoglobin disorders and white blood cell cancer like leukaemia may present with retinal haemorrhages, retinal vascular disorders, and optic nerve swelling etc which can be diagnosed by routine eye examination.
AIDS can present with varied ophthalmic features affecting various parts of the eye and sometimes the suspicion of AIDS is doubted by first presentation to an ophthalmologist. Because of immunodeficiency caused by HIV virus various parts of the eye are affected by other organisms including bacterial, viral and fungal infections leading to keratitis, uveitis, retinitis and even cancer.
Pregnancy causes a shift in hormonal and fluid status resulting in self-limiting physiological changes in the eye which may occur in any trimester.
But, if the mother has a pre-existing pathology like diabetes, progression of diabetic retinopathy may occur because of pregnancy. So, it is essential to assess baseline retinopathy and establish a monitoring plan customized to each mother individually.
Hypertension may get elevated during pregnancy and lead to fits and retinopathy changes which also needs regular monitoring.
Awareness of these associations with eye problems is the first step in diagnosis and management of these complex patients and hence a comprehensive eye examination should be included as a part of routine testing.