yes, there is. most eye doctors dont do it b/c it doesnt mean all that much. we usually consider anything over about 20/400 to be not-very-functional vision, so we usually dont bother measuring much worse than that.
but any (and every) acuity can be accurately measured.
the fastest way to do it is by using finger counting:
20/800 CF10' (Count Fingers at ten feet)
20/1000 CF 8'
20/1143 CF 7'
20/1333 CF 6'
20/1600 CF 5'
20/2000 CF 4'
20/2666 CF 3'
20/4000 CF 2'
20/8000 CF 1'
http://www.mdsupport.org/library/acuity.html
there are other ways to do it, but they involve some serious math:
http://www.ascrs.org/publications/jcrs/guestfeb04.html
the question is, why do you need to know? if its a curiosity thing, you can certainly satisfy it using the above methods, but most things that would would need good acuity for (military, etc) require much better vision than 20/400.
Well, my daughter (11 months) has optic nerve hypoplasia. Her vision is assumed to be quite low. Some of the parents in my ONH group have had their kids' acuity tested at as good as 20/400, so I wanted to attempt to understand what my daughter may or may not be seeing. If I can accurately score my acuity, perhaps it would give me insight into her abilities.
ah, a legitimate question.
in children really the only way i know of to fairly accurately test an infant or toddler's visual acuity is with a rotating optokinetic nystagmus drum. pretty much only a pediatric optometrist or ophthalmologist will have a set of them, and eye/vision research institutions. i know my optometry school had them...SUNY Optometry in Manhattan, NY
you may already know this but a rotating optokinetic nystagmus drum is a cylinder that turns. the cylinder has vertical black & white "stripes" on it (a "grating") of varying sizes. larger/fatter "stripes" are for lower acuity like 20/400, 20/2000, etc. smaller/skinnier "stripes" are for better acuity like 20/40, etc.
the drum is placed in front of the child and rotated. if the child has good enough acuity to see the size of the grating/"stripes" then the child's eyes will dart back & forth, following the grates. this is called "optokinetic nystagmus" or OKN. the idea is keep getting smaller in size until you find the smallest grating size that produces an OKN response and thats the infant's acuity.
you said you are nearsighted (thats negative or minus) -5.00 in your worst eye. thats an acuity of approximately 20/500 or so
The pediatric ophthalmologists have used the drum before, with limited results. How can they distinguish between optokinetic and regular nystagmus? My daughter's strabismus and nystagmus are both pretty profound. We're going to schedule a visual evoked potential test, to help determine how many impulses are reaching her visual cortex. She does not track objects, and has a very limited response to visual stimuli. We're hoping for the best, and preparing for the worst. She receives vision therapy once a week as well.
Thank you for your time.