Changes in vision, changes in the appearance of the eye, or an abnormal sensation or pain in the eye, are the three symptoms indicative of eye disease, according to the Merck Manuals.
While most eye disease symptoms develop as a result of a problem in the eye itself, sometimes they may be indicative of a problem elsewhere in the body, such as in the brain, or as a result of an illness, such as diabetes which can affect several organ systems in the body.
Changes in vision
These can include the development of the following symptoms, most of which can be symptomatic of a range of conditions:
Nearsightedness is caused by an elongation of the eyeball over time, and this makes it difficult to clearly see objects far away.
Read more on vision problems.
Farsightedness is caused by the shortening of the eyeball, according to the John Hopkins Medicine Insitute and makes it difficult to see objects clearly that are close by. Many older people wear reading glasses for this reason.
Blurry or hazy vision, or loss of specific areas of vision, can affect one or both eyes and is the most common vision symptom, according to the Merck Manuals. Any sudden changes in vision, or sudden inability to focus clearly should be a cause of concern. Sudden loss of a specific area (such as central or peripheral) should prompt a visit to an ophthalmologist.
Double vision means you don’t see a single clear image, but one that appear to repeat itself. Headaches, nausea, a droopy eyelid and misalignment of the eyes are all symptoms which could accompany double vision.
Floaters are specks or strands that seem to float across the field of vision, says the American Foundation for the Blind. These are actually shadows cast by cells inside the clear fluid that fills the eye. They could be harmless, but should be checked out as they could point to something serious such as retinal detachment.
Loss of vision refers to a loss of vision in someone who was able to see before. This cannot be corrected with glasses or contact lenses. Sometimes surgery is also not an option. Partial vision loss refers to very limited vision, and complete blindness means you cannot see anything, even if you look straight into a bright light, according to the National Institutes of Health.
Night blindness refers to the inability to see clearly in the dark, or adapting to the dark especially after coming out of a brightly lit environment. This can either be genetically inherited, or be a symptom of several eye diseases.
Impaired depth perception means a person has difficulty distinguishing which of two objects is closer to him or her, say the Merck Manuals.
Changes in the appearance of the eye
These symptoms could include (but are not restricted to) any of the following:
Redness or swelling of the eyes, which have a bloodshot appearance. The eyes could be watery and itchy as well, depending on the causes, of which there are many (from conjunctivitis, to allergies, to an object in the eye, to name but a few). A discharge from the eyes is also possible.
Read more about eye infections.
Redness and swelling of the eyelid. Eyelash follicles could be inflamed, or there could be a stye on the eyelid or it could be the result of allergies or an injury.
Cloudy appearance of the eye. These can be symptomatic of cataracts, which occur when a buildup of proteins make the lens of the eye appear cloudy.
Eyelid twitch. This happens when eyelid muscles spasm involuntarily over a period of time.
Squint gives the appearance of the eyes not being lined up in the same direction. Even after surgical correction, this condition can reappear.
Bulging eyes could be a symptom of hyperthyroidism or of an auto-immune disorder called Grave’s disease.
Droopy eyelids can be a sign of exhaustion, or of ageing, of migraines, or of a more serious medical problem, according to the National Institutes of Health.
Read: Common eye injuries
Pain in and around the eye
Pain on the surface of the eye is called ocular pain, and pain within the eye orbital pain. Ocular pain can be caused by a scratch or slight injury to the cornea of the eye or the presence of a foreign object and often causes redness of the eye. Orbital pain can be sharp or throbbing and go beyond the surface. There are many possible causes of this.
Whereas pain in the eye often resolves itself, the Merck Manuals warn that it should be a cause for concern if it is accompanied by vision loss, vomiting, fever and muscle aches, eye bulging and difficulty in moving the eye in certain directions.
Trauma to the eye or surrounding facial areas can also be the cause of pain.
What is eye disease?
Causes of eye disease
Diagnosing eye disease
Image: Girl having eye pain from Shutterstock