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Eyes are endlessly complex, which means that there are an endless number of ways that they can go wrong. Most of us can imagine accidents that would lead to blindness, and we all know of nearsightedness, cataracts, astigmatisms, and glaucoma. But that hardly covers the things that can go wrong with eyes. Here are 9 rare ways to go blind.
1. Charles Bonnet Syndrome
Charles Bonnet Syndrome is characterized by visual hallucinations, often of faces. It usually comes after someone already has some eye loss from another cause, particularly macular degeneration. This is not a condition caused by mental illness, and those who have it are aware that the hallucinations are not real, but unfortunately, there is no treatment beyond that self-awareness.
2. Retinitis pigmentosa
This is a degenerative disease that results in blindness due to loss of the use of rods and cones. It often manifests in the form of problems perceiving light appropriately. RP is an inherited condition for which there is no cure, but it can be treated with vitamin A to slow the onset of blindness.
3. Morning Glory Anomaly
Fun fact: your dear author has a morning glory anomaly. Also called morning glory syndrome, a morning glory anomaly is a birth defect in which the optic nerve is malformed in such a way as to look like a morning glory (thus the name). It leads to partial blindness in one eye and can also be associated with malformations of the head and face. Again, there is no current treatment for the anomaly (although yours truly is hoping for a cyber eye).
4. Cat eye syndrome
Have you ever wanted cat eyes? Well, it is possible with this chromosomal disorder. About half of all patients with cat eye syndrome have pupils that appear vertical, leading to the name. Technically this syndrome does not lead to blindness, but it does come with a whole host of other possible medical issues, such as a cleft palate, kidney problems, skeletal problems, or cardiac defects. Many of these related problems can be treated as they would in any other individual.
True polycoria is incredibly rare, although there are a variety of other conditions that present with the same appearance. Polycoria is having multiple pupils in a single iris. It can either be congenital or caused by disease, but in order to be considered true polycoria, both pupils need to have a pupillary sphincter (meaning they can dilate on their own). Polycoria does not necessarily impair vision, but it does look extremely cool.
6. Aniridia eye disorder
On the other side of the spectrum from polycoria is aniridia, or absence of the iris. Generally this leads to blurrier vision and increased light sensitivity, but is also often linked to other eye problems. There is a wide variety in what other symptoms and problems can present with aniridia, which means that the range of vision for individuals with aniridia is quite large. Typically, aniridia is a congenital disorder, although it can also be caused by injury.
7. Acute Zonal Occult Outer Retinopathy (AZOOR)
If there is an eye disease that you don’t want to get, it’s AZOOR. This is a sudden onset disease that includes flashing lights and loss of vision in otherwise healthy (although generally myopic) individuals. Most patients first have this in one eye, but it typically spreads to both. Of course, there is no cure.
Aphakia is the lack of a lens on the eye. This results in severe farsightedness (as the lens is what allows the eye to focus), difficulty adjusting to near and far objects (accommodation), and also the ability to see ultraviolet light. It can also lead to complications like glaucoma and retinal detachment. Generally it’s treated with an artificial lens like glasses.
9. Rod Monochromatism
This is a hereditary condition that sometimes improves with time, but generally includes severe blindness and the inability to see color. Patients with this condition don’t have functioning cones, leading to no color vision, severe light sensitivity, and day blindness. There is a variant on this condition called Blue Cone Monochromatism, in which only the blue cones function. This allows patients to see “blue” and can sometimes diminish the other symptoms as well.