John Godfrey Saxe was a 19th-century American lawyer, businessman, newspaper editor, and author. He is best known for a poem inspired by the Civil War, his humorous retelling of a Hindu parable about six blind men who were “to learning much inclined” and went to visit an elephant, each endeavoring to describe what an elephant was like. One came across the brute’s slab-like side and affirmed the pachyderm was akin to a wall. One palpated the tusk and was convinced the beast was spear-like, while the fellow who grasped the squirming trunk boldly up and spake: “I see,” quoth he, “the Elephant is very like a snake!” Each was partly in the right, and all were in the wrong! Vision requires one to see the whole thing; any erosion of the image will mislead and might have bad consequences. For instance, mistaking the rear end of Dumbo for the front while trying to offer a tasty morsel may lead to a large deposit and not of the financial kind!
Visual erosion can come on slowly and imperceptibly and has many causes, from cataracts and glaucoma to diabetes, genetic issues, parasites, and infections among many others. And then there is macular degeneration, which appears most commonly over age 50, may have a family history, is associated with obesity, poor diet, smoking, and hypertension and is more common in Caucasians and women. Like all eye diseases that threaten to steal sight, early diagnosis increases the chance for successful treatment, so if you read no further, please book an eye check-up now!
The macula sits in the center of the retina, the light-sensitive tissue at the back of the eye. It is about ¼ inch across (the size of a pencil tip) and is responsible for processing central vision, critical for seeing fine details clearly, reading tiny writing, recognizing faces, and distinguishing colors. The remainder of the retina processes the broader area, critical for navigating our environment and detecting movement, which is why those with glaucoma cannot see stuff happening in the periphery of their visual field. As a pilot, a functioning macula is the difference between being able to read a chart, scan instruments, or spot traffic; if damaged, your flying privileges may be at risk. It may also lead to you and your passengers being damaged.
Macular degeneration refers to a group of chronic eye diseases where a damaged macula leads to deteriorating central vision and is a common cause of visual impairment in Americans. There are three types:
With both types of adult macular degeneration, the disease may have progressed before one recognizes that vision is deteriorating, with symptoms like blurry central vision, problems recognizing faces, a scotoma or “hole” in one’s central vision, straight lines seeming to be wavy and colors losing some of their vibrance. Even the slightest suspicion of this should take one to an eye doctor promptly.
Having taken a history, the doctor will perform a thorough evaluation of the eye after dilating the pupil with drops; always take sunglasses to an eye appointment and do not plan on driving after the check-up. Some of the things the specialist will look for are the drusen referenced above, pigmented areas, an Amsler Grid, (a tool to check for distorted vision), a high-resolution image of the retina called Optical Coherence Tomography (OTC widely available at eye check shops), and a test called Fluorescein Angiography where dye is injected into a vein (in your arm) and if there is wet AMD, the doctor will see abnormal or leaking vessels.
Other tests include color vision evaluation, obtaining a photograph of the back of your eye, electroretinography (ERG), which shows how your retina responds to changing light, and perhaps genetic tests if Stargardt’s or other rare macular dystrophies are suspected.
To help control dry AMD, stopping smoking, eating a healthy diet, and controlling blood pressure can help. The large Age-Related Eye Disease Study 2 (AREDS2) evaluated whether daily vitamin and mineral supplements might help, especially for those with many drusen. Results suggested that Vitamins C and E, zinc, copper, lutein, and zeaxanthin may help and may also lower the risk of wet AMD and eyesight loss in those who have already lost sight in the other eye from AMD. In 2023, two new drugs were approved that show promise for certain subtypes of AMD; Syfovre (pegcetacoplan) and Izervay (avacincaptad pegol).
In the late 1980s a compound called VEGF (Vascular Endothelial Growth Factor) was discovered that was involved in stimulating new blood vessels. For wet AMD, injections of anti-VEGF drugs that suppress new blood vessel formation, a biological process called angiogenesis (from Greek, angio = blood vessel, genesis = creation) have proven very beneficial. However, medications to block new vessels (ranibizumab, aflibercept, and bevacizumab) must be injected into the eye, which sounds like something a James Bond villain would do! Prior to this, zapping the vessels with a laser or photodynamic therapy was performed, although this is used much less now.
In the future, gene therapy or stem cell transplants may offer hope, as may implants to leach out anti-VEGF drugs to preclude the need for frequent injections.
If diagnosed with macular degeneration, pilots must self-ground and report to the FAA with a detailed ophthalmologist report including diagnosis, visual acuity, and treatment plan. Results from OCT scans and Amsler grid should be included if applicable. Many pilots with early or well-controlled AMD may qualify for Special Issuance Medical Certification. AMD is not an automatic grounding condition but requires vigilant adherence to treatment and monitoring as the FAA requires periodic follow-up exams and documentation of stable vision. If severe or rapidly progressive, especially if there is a central scotoma or poor visual acuity, denial or restriction may ensue.
I mentioned Mr. Bond above; his boss in several movies, M, played by Judi Dench, used her celebrity to raise awareness of AMD. Other famous people have been victims, including Stephen King, who has scared us with his tales and now deals with this scary condition.
In early episodes of Sesame Street, we heard of Mr. Aloysius Snuffleupagus (Snuffy to his friends) but never saw him. This led to many thinking this elephant existed only in Big Bird’s imagination. We need to see to believe, and the moral of the blind men and the elephant is how we tend to form opinions with incomplete data. Just as you would never embark on a flight with an incomplete set of en-route or airport charts, don’t allow AMD to tear up your view of the world. That elephant in the room looks best if we can see the whole Snuffy!
Fly Well!
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