Healthy Pilot #3: Eyesight—Common Diseases and Risk Factors
At some point, we all have to deal with fuzzy vision, floaters, and vision-associated headaches. But for a pilot, any eye trouble can be a game changer.
Yes we all fumble for our glasses when we pull out the checklist. And while your distance vision is still sharp when ATC calls out traffic, things get a little fuzzy when you transition back to the panel. Maybe those drug-store cheaters aren’t hacking it anymore as you load your flight plan into your G1000, or you’re having trouble finding the “squawk VFR” button on your transponder.
Right now these might be minor annoyances. But with vision issues, little things become big things if left unaddressed. And face it, for a pilot, eyesight is the ballgame.
That hits home when you run across line 18(d) on Section Two of the Basic Med self-reporting checklist. You’re obligated to correctly explain health status to your personal physician, your partner in getting you certified. He or she will want to know about any medications you might be taking, or any history of trouble. When it comes to your eyesight, answering these questions honestly gets easier with better information.
Here are some common problems many of us face, and some basic risk factors. As always, your most important resource if you suspect you have an eye problem will be your ophthalmologist. The information here comes from AVweb’s sister website, University Health News. We hope it will lead to better communication between you and your doctor so you can stay safe in the cockpit.
Age-Related Macular Degeneration
This condition affects the central portion of the retina, the source of the sharpest images. It causes slow erosion of central vision necessary for reading and recognizing faces. Age-related macular degeneration (AMD) accounts for more than half of blindness, and the leading cause of vision loss in Americans over age 65. As yet there is no cure for AMD, so seniors must be vigilant about regular eye exams.
The first and most common form is dry, or non-exudative. This occurs when degenerated cells from the macula build up under the retina. The only early symptom may be slightly blurred. Dry macular degeneration can progress to the more dangerous wet form.
The less frequent but far more serious wet, exudative form accounts for most macular degeneration blindness. In wet AMD, abnormal blood vessels grow under the retina, leaking blood and fluid, lifting and damaging the retina. Fortunately, only about 10 percent of age-related macular degeneration progresses to this form. Untreated, wet AMD progresses much faster than dry and requires immediate treatment to preserve vision.
For unknown reasons, retinal structures break down which some experts believe leads to both dry and wet macular degeneration. Some researchers point to free radicals as the source. Other possible causes are general, low-grade inflammation throughout the body, genetic markers that increase risks, or high blood levels of a protein called cystatin C
Smoking, high blood pressure and high LDL cholesterol all raise the risk of developing age-related AMD. Other risk factors that you can control are:
Dietary factors/poor nutrition
Overexposure to ultraviolet light
Risk factors you cannot modify:
Aging can affect the shape of the eye and/or the functionality of its components. Refractive errors occur when the anatomy, or shape, of the eye prevents light from properly focusing on the retina. Age also affects the eyes ability to produce tears.
The most common forms of refractive errors are nearsightedness, farsightedness, and astigmatism. The most common age-related vision problem is presbyopia, where the eye begins to lose its ability to focus due to loss of lens flexibility. It’s a gradual process that happens to everyone who lives long enough, which usually requires corrective lenses beginning at some point in your 40s. Chronic dry eye is another common condition of aging eyes.
Nearsightedness (myopia) occurs when the eye is too long from front to back, causing distant images to fall short of the retina. A nearsighted person has trouble focusing on distant objects but can see close-up objects clearly.
Farsightedness (hyperopia) -a farsighted person can clearly see distant objects, but close objects are fuzzy. Shorter-than-average eyes cause hyperopia, or farsightedness, where the focal point of close objects falls behind the retina.
Astigmatism occurs when the cornea is oblong rather than round. This inhibits focus for both near and far objects, leading to distorted vision.
Presbyopia is the loss of lens flexibility, and thus clear vision, brought on by aging,
The eye’s clear lens consists of protein and water, arranged in a precise pattern. As you age, the proteins clump together, causing the lens to cloud and turn yellow. This is a normal process that occurs in almost everyone. In about half the population, the lens eventually gets too cloudy for clear vision.
There are three types of cataracts:
Nuclear cataracts form in the center of the lens and are the most common age-related cataracts.
Cortical cataracts occur at the edge of the lens and progress toward the center.
Posterior subcapsular cataracts form at the back of the lens and are more common with injury, long-term steroid use, or diabetes.
The exact cause for cataracts is unknown, but one likely contributing factor is a class of compounds called oxygen-free radicals. They are generated by natural biochemical processes, notably metabolism, as well as by environmental pollutants, including cigarette smoke. In younger people, these free radicals are sopped up by endogenous antioxidants, but the body’s ability to produce antioxidants decreases with age.
Ultraviolet light also contributes to cataract formation, probably partly by generating free radicals.
Everyone is at risk for cataracts as they age, but some have greater risks. Women are at high risk than men, especially those who receive hormone replacement therapy (HRT) after menopause.
Smoking also increases the cataract risk, and it can take 10 to 20 years after smoking cessation for your risk to drop.
Taking certain medications, like steroids and some SSRI antidepressants, also may make you more prone to cataracts.
Other risk factors for cataracts include:
Family history of cataracts
History of eye injury
Previous eye surgery
High exposure to sunlight
High exposure to radiation
Glaucoma is an eye disease where excess pressure irreparably damages the eye, causing blindness. It is the leading cause of irreversible blindness in the world. In the U.S., an estimated two million people have glaucoma. An equal number of people probably have the disease but don’t know it.
Because symptoms don’t manifest until the disease is very advanced, glaucoma is a sneaky vision thief. Yet, fewer than 10 percent of Americans surveyed know that glaucoma has no warning signs, according to the National Eye Institute.
Glaucoma treatments have improved with fewer side effects. Because doctors can usually control glaucoma once detected it’s important to seek treatment right away and be vigilant about taking your medications.
The most common form is primary open-angle glaucoma. A malfunction in the meshwork that drains the aqueous humor from the “open angle,” where the iris and cornea meet, is the likely cause. In open-angle glaucoma, the drainage slows, leading to a surplus that builds pressure in the eye, damaging the optic nerve and retina.
Angle-closure glaucoma stems from a congenital malformation of the eye’s drainage system. When this develops, the angle into which the aqueous fluid normally drains becomes blocked. The eye pressure increases so rapidly that vision loss can progress to blindness within just one or two days if not treated aggressively.
Glaucoma is caused by a build-up of pressure in the eye from excess or blocked aqueous humor. The pressure builds, eventually damages the retina and optic nerve, causing blindness. Glaucoma can also stem from an eye injury, inflammation, infection, a very mature cataract, diabetes, lupus, or certain medications (particularly steroids).
Everyone over the age of 60 is at increased risk for glaucoma, but the following factors increase risk even further:
African-Americans over age 40
Family history of glaucoma
History of previous eye injury
History of steroid use
Other related health problems, including high blood pressure and migraine headaches
Lupus and diabetes are also risk factors for glaucoma. Heart disease is linked to glaucoma. Though high eye pressure is a risk factor and often an early warning sign of glaucoma, it doesn’t necessarily mean that nerve damage is occurring. Some people with high eye pressure never develop glaucoma.
Diabetic retinopathy, a complication of diabetes, afflicts approximately 4.2 million Americans—roughly one-third of whom have diabetes. It is the leading cause of new blindness in people between the ages of 20 and 74.
Nonproliferative diabetic retinopathy is the disease’s early stage. It begins with tiny bulges in weakened blood vessels of the retina that leak blood and fluid into the retina. More blocked blood vessels characterize moderate nonproliferative retinopathy and during the final, severe stage parts of the retina lose their blood supply.
New blood vessels begin to grow on the retina to bolster the blood supply. This is the most severe stage, called proliferative diabetic retinopathy. Up to 75 percent of people with nonproliferative will progress to the proliferative form within one year
Diabetes damages tissue throughout your body, including blood vessels in the eyes. Without proper blood flow, the retina and optic nerve incur permanent damage.
The longer you have diabetes, the more likely you will develop retinopathy. The risk rises from 10 percent within five years post-diagnosis to 70 percent after 15 years.
Everyone with diabetes is at risk for diabetic retinopathy. Your risk increases the longer you have diabetes and the less you control your blood sugar. Other risk factors include:
High blood pressure
High cholesterol levels
Here are some additional useful links:
What Is Presbyopia
Eating for Eyesight
Research Sheds Light on Vitamins for Eyesight
Aging Eyes and Declining Eyesight
Dry eye syndrome
Glaucoma Symptoms, Treatment, and Prevention
Is Glaucoma Hereditary?
Eye Pressure Can Indicate Oncoming Glaucoma
Cataract Replacement Lenses