So You Want To Blind Your OC, Disease Edition
Because bloomingcnidarians asked, and the answer got long. Very long.
Edit: I should also say that while I am a practicing optometrist currently in the middle of a residency in low vision, I am sighted myself with no visual impairment. Reported symptoms are only based on what patients have told me and case reports, not from personal experience; you may have found something else entirely to be true, and I would love to hear about it!
OKAY. Let me go over a couple of the most common misconceptions about low vision/blindness first, which will make everything easier.
Reminder: a visual acuity of 20/20 is considered “normal” vision; in layman’s terms, that means you can read at 20 feet what an average population can see at 20 feet.
20/15 vision is “better than perfect;” you can read at 20 feet what a normal population must move up to 15 feet to read.
Worse acuities, such as 20/200, mean that you have to move up to 20 feet to read what a normal population can read at 200 feet.
True blindness is defined as is the total inability to perceive light. Unless extremely, extremely severe eye disease is present, it is actually really hard to go totally blind in both eyes.
People who have developed total blindness very rarely describe it as the world going black. The majority describe nondescript grey fog or colorless backgrounds with occasional shooting lights.
This is different from “functional blindness,” where a patient has no useful vision but may still be able to perceive light vs. darkness, blurry colors, or very, very large letters. These patients may still have quantifiable visual acuities, but because their vision is so poor they do not use their eyes in any meaningful way.
Legal blindness (in the United States) is defined as best-corrected visual acuities worse than 20/200 (in the better eye), or a visual field restricted to 20 degrees (also in the better eye).
Please note that this is BEST-CORRECTED. This means that with the best and most accurate glasses I can put in front of the eye, it will never see better than 20/200. A lot of people with high prescriptions (especially nearsighted people) like to say, “I’m legally blind without my glasses.” This is not possible as legal blindness is, by definition, with glasses on. A patient who can’t see the big E on the eye chart without glasses, but who can then put their glasses on and read 20/20, is not legally blind. They have a high prescription, full stop.
Simple refractive error is not a disease. Even if that prescription gets worse by a step every other year, if the eye is still 20/20 in the glasses and there is nothing wrong with any of the eye’s physical structures, they are not legally blind.
Continued under the cut. Did I mention this is long?
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