The eyes have it

Tuesday, April 21, 2009

Eye placement tells us that humans are predators. Two eyes placed in front of the face, looking forward allows for binocular vision, depth perception and the ability to function in a 3D world. The eyes, though, are barely protected by cheekbones and the forehead and are at risk for a variety of injuries and Channing Frye suffered a most common one playing in the NBA playoffs this weekend. An inadvertent poke by an opponent’s finger caused a corneal abrasion and all of a sudden, those 3D moments vanished.

Corneal abrasion or a scratch on the surface of the eye can be incredibly irritating, causing a painful, red, watery eye. The cornea is the clear covering of the front of the eye that allows light to enter the pupil and project on to the retina. It’s important that the light and the images it transmits avoid distortion by any of the structures in the eye, otherwise vision can become blurry.

It’s common for the cornea to be scratched by an errant finger or a pillow edge or a piece of debris. Sometimes, the exact injury can’t be remembered and the patient feels like there is something in the eye. Unfortunately the eye can’t tell whether there is something on the cornea or whether a divot or scratch exists on the corneal surface. It just knows that as the eyelid blinks, there is a foreign body sensation. The doctor can make the diagnosis with the help of a slit lamp (a specialized microscope) that is used to examine the surface of the eye, look underneath eyelids and measure pressures within the eyeball.

A red, irritated is often due to a superficial injury but other causes may exist, some serious and some not so serious. Not so serious can include things like conjunctivitis or pink eye, where there is redness, itchiness and perhaps crusting and pus. More serious are diagnoses like glaucoma, an increased pressure within the eye. While common things are common, the doc is at least going to consider alternatives before settling on a final diagnosis. One frustrating cause of corneal abrasion, at least for the doctor, are those caused by foreign bodies trapped under the eye lid. This can cause numerous abrasions as the cornea gets scratched with every blink of the eye. The foreign body can be very small, difficult to find and often a visit to the ophthalmologist is required to find and remove it.

Corneal abrasions can be painful but they tend to heal quickly. The cell turnover of teh eye is relatively fast, usually a day or two, so that abrasions heal quickly. Compare that to cell turnover in other parts of the body like the hands and feet, where it can be measured in weeks, so cuts and scratches may take much longer to resolve.

The treatment for a cornmeal abrasion is supportive. Eye drops may be prescribed to minimize pain and inflammation. Sometimes antibiotic drops are used to prevent infection. And contact lens use isn’t recommended until the eye has completely healed. Patching eyes shut no longer is recommended. The ability for the eye to heal quickly depends upon oxygen getting to the eye surface and patching decreases that possibility.

After a day or two, the injury is resolved and all is well. In the meantime, blurry vision is the norm and for a pro basketball player, like Channing Frye, the ability to shoot baskets is unlikely to happen. Hopefully, his eyes have read the textbook and will be ready to play when the next playoff game tips off.

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