Glaucoma has two possible meanings derived from ancient Greek; glaukos meaning either to glow, or appear blue-green, likely referring to an eye affected by cataract when the lens is occluded, just like clouds blocking sunlight, or a blazing red, inflamed eye. Vision is a biological masterpiece; first, the iris (colored part) moderates how much light enters, enlarging in dark environments and constricting under bright conditions. The lens focuses light rays, and these then pass through two liquid chambers, called humors (from Latin, meaning moisture) which nourish and shape your baby blues. Front and center, between the cornea and iris, a chamber is filled with aqueous humor and behind that, a thicker, gelatinous vitreous humor. An image is then projected onto the retina where specialized cells send coded messages to the brain, clarifying that those are runway, and not taxiway, lights ahead!
Glaucoma is commonly due to raised pressure inside the eye which leads to retinal cell damage, eventually causing partial, or total vision loss. In some cases, pressure may be normal, yet damage occurs; in others, pressure is raised, but harm is absent. Aqueous humor is produced by the ciliary body, part of the circular muscle that changes iris size, and fluid then drains away, to be continuously refreshed. There are several types of glaucoma, most commonly, painless, primary open-angle glaucoma where fluid drainage is impaired. Initially, symptoms are absent until one notices a partial visual field loss, usually peripherally, although our brain might “fill in” missing parts. If this visual deterioration is not appreciated, glaucoma may present due to the consequences of being unable to see, for instance, an obstacle when taxiing, or missing converging traffic! Conversely, the less common acute angle-closure glaucoma, produces sudden severe pain, redness, nausea and vomiting, headache, and impaired vision; so please, never assume a red eye is “just” conjunctivitis and seek urgent medical help as blindness might otherwise result. Glaucoma can also be inherited or occur secondary to trauma, various conditions such as diabetes, several inflammatory diseases, and various drugs, including steroids.
Given that symptoms are sneaky, checking for glaucoma should be part of your annual human maintenance. When having an eye exam, in addition to reviewing visual acuity with the familiar Snellen charts, ensure that glaucoma is excluded. An ophthalmologist will likely apply numbing eyedrops and will also dilate the pupil, allowing a good look at all parts of eye anatomy. Pressure is painlessly measured with a tonometer instrument, either using either a small puff of air or a gentle touch.
If diagnosed, most cases are treatable with eyedrops including various classes of medicine that reduce eye pressure including prostaglandins (e.g., latanoprost), cholinergic agents (e.g., pilocarpine), and the cutely named Rhok inhibitors (abbreviation of Rho Kinase inhibitors such as netarsudil). And no, I do not know if Bono uses this medication.
Other substances reduce fluid production including beta blockers (e.g., timolol), alpha-adrenergic blockers (e.g., apraclonidine), and carbonic anhydrase inhibitors (e.g., dorzolamide). As always, if a medical can be granted, be aware that some drugs are, and others are not, allowed by the FAA, so check the AOPA database (https://www.aopa.org/go-fly/medical-resources/search-faa-medication-database
) and speak to your AME.
For those patients who cannot tolerate eyedrops, when medical treatment fails to control disease, or in acute cases, there are other options. One can perform trabeculoplasty, an outpatient, local anesthetic laser procedure to open drainage channels, or laser iridotomy and iridoplasty, where the iris is cunningly shrunk, creating better drainage. Alternatively, laser can eradicate parts of the ciliary body, thereby reducing fluid production and, in some countries, although not yet in America, an ultrasound technology can do the same, seemingly with more precision. Finally, just as blocked heart arteries are bypassed, a tiny shunt can be placed in the eye chamber, redirecting excess fluid into a small reservoir under the cornea.
If diagnosed, immediately self-ground and inform your AME as flight is not permissible with visual field loss or “significant change in visual acuity.” However, FAA may choose to allow a special issuance on provision of an “Ophthalmological Evaluation for Glaucoma” (FAA Form 8500-14) from a qualified ophthalmologist. If glaucoma is secondary to trauma or a primary illness, it is that which will define the certification situation. However, this may only affect one eye, and if disease progression has stopped, or is slow, normal certification may be allowable if the non-affected eye is normal. When the angle limiting drainage is tight, certification is usually not feasible as there is a risk of sudden, severe vision loss and other symptoms that could incapacitate a pilot. Three months after an interventional treatment, certification may be feasible if pressures are normal, and symptoms controlled. An FAA worksheet is available at: https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/media/c-caciglaucoma.pdf
In 2002, during a glaucoma awareness interview, John Glenn stated: “I’ll never forget the sight of Earth as I looked from my Friendship 7 Mercury capsule in 1962 or 36 years later from the space shuttle Discovery.” Sights he might not have seen but for an early glaucoma diagnosis and treatment. Kirby Puckett won two World Series and sadly died at 46 from a massive brain hemorrhage. He had 210 stolen base attempts, but glaucoma had one attempt and scored. And in the opening line of U2’s 1987 hit “With or Without You,” Bono sang, “See the stone set in your eyes.” It is a dark tune, about being defeated in a relationship with oneself. Please avoid the dark, don’t have stone-set eyes, and take glaucoma seriously.
You can send your questions and comments to Dr. Sackier via email: [email protected]
and listen to his weekly podcasts at: https://www.emg-health.com/omnipresent/?category=podcasts&therapeutic_area=healthcare