Looking into a patient’s eyes can provide a doctor with a wealth of information regarding your general health. The following is a list of typical things your doctor will be on the lookout for when he holds that ophthalmoscope in front of your eye:
Around the eyes
Swelling or puffiness around the eyes may indicate allergies or infections or even kidney problems. Your doctor will compare both eyes and note any signs suggestive of allergies like redness, irritation or small lines that indicate persistent rubbing.
Redness, warmth, tenderness and swelling may indicate soft tissue infections. When unusual swelling is present around your eyes, your doctor might also test your urine to check for protein that may suggest kidney problems.
If the inner lining of your eyelid (conjunctiva) is red, it may indicate to your doctor that you’re suffering from anaemia. One of the signs of anaemia is pale conjunctiva. He will also look for infections of the eyelid (blepharitis) caused by bacteria or infections of the inner lining of the eyelids.
He will ask you close your eyelids and look for any signs that your eyelids are not closing properly. This may indicate problems with the nerves or muscles responsible for closing your eyes.
Movement of your eyes
The muscles responsible for the movement of your eyes are controlled by nerves coming directly from your brain. Damage to or conditions affecting these nerves may have altered the movement of your eyes, causing squinting, or even the inability to move your eyes in certain direction. Your doctor will test the nerves by asking you to follow a light or object.
Position of your eyes in the socket
Masses behind your eyes or in your skull and even dehydration can have an effect on the position of your eyeballs in the socket. With abnormal growths, your one eye might protrude more than the other. With dehydration, the eyes often appear sunken.
With thyroid problems your eyes might appear as if they are protruding from their sockets, giving you an “amazed” look.
On the eyeball itself your doctor will be on the lookout for burst blood vessels. He will also look for growths on the eyeball like a pterygium – a fleshy-pink, non-cancerous growth on the eyeball that extends toward the pupil (usually not covering the pupil).
A rare, but important find is what looks like a mole on the eye, which may be melanoma. Alert your doctor of any notable changes in the colour of your eyeball.
Read: Eye diagnosis: art or science?
The little black hole (pupil)
Your pupil regulates the amount of light entering your eye. This is controlled automatically by a brainstem reflex. Your doctor will test your pupils by briefly shining a light onto your eyeball to test how your pupils react to light. He will compare both sides and test each pupil individually.
The inside of your eye
Occasionally your doctor will look at the retina of your eye. The retina is the lining on the inside of your eyeball which allows you to see. The retina has a very rich blood supply from small blood vessels.
Chronic conditions like high blood pressure and diabetes can affect these small blood vessels and essentially affect the retina, causing a decrease in vision.
Looking at the back of your eye can be very uncomfortable as the doctor will need to come really close to your eye to get a clear picture of your retina. In some cases he will use eye drops that will temporarily cause dilation of your pupil to get a better view. As a result of the eye drops, you may experience significant blurry vision. It is best to lie down till the effect of the drop has worn off.
Your doctor will also look at the place where the optic nerve attaches to the eye, called the disc. The optic nerve comes directly from the brain.
If there is increased pressure in your skull (due to meningitis, bleeding from a stroke or brain swelling), the disc may look pale, or the blood vessels may have a different appearance.
Read: Your eyes are a window to your brain health
Pressing on your eyes
Measuring the pressure in your eyeballs is a test for glaucoma – a condition where the pressure in the front chamber of your eye is too high, causing pressure on the optic nerve. This may lead to vision loss if left untreated.
There are special tools available to measure the pressure exactly, but your doctor may make a gross estimate by pressing on your eyeballs with your eyelids closed. If he notes any difference in pressure, he will formally test the pressure in your eyes.
Examining the eyes forms an important part of any physical exam. To list every possible condition that may affect your eyes is not possible, but rest assured that your doctor is trained to identify and act on conditions affecting your eye.
An ophthalmologist (a doctor specialising in eye care) will do more indepth investigations.
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Image: Doctor examining patient's eyes from Shutterstock