Ophthalmology & Optometry/near add calculation


i just need some clarity....i hv a situation where two colleagues r arguing on hw to determine the ner add. one argue that it is a binocular test n fter distance rx da formula age -35=x/10=y y being the estimated add...then it is put up n binocularly the optometrist refines the final reading rx

on th other hand...the cross cylinder procedure is used....where the ptient looks at the cross cyl and plus-minu 0.50's re placed in front of the patients eyes at first th tet is done monocularly n then the patient is left at last vertical...after which th patient is tested from thi point binocularly n den brot bk to c the lines equal or first horizontal clear.

the argument is in the second procedure it is possibleto gt slightly or differing add and in th first the add will alway be th same for botheyes.....can u plz clarify so we can all us the better n correct procedure

Dear Aysha,
Sorry for the delay in reply.
However, the near add has no formula. One needs to check both eyes independently (similar to what you have described in the second procedure). The individual best corrected power needs to be adjusted for both eyes, by asking the patient to keep the book where they usually hold it and adjust the powers to suit both eyes.

This needs to be done after the far distant has been refracted.

Dr Shroff

Ophthalmology & Optometry

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Dr Anand Shroff, MD, FICS


I can answer any question on eye care, expertise in Laser eye surgery, LASIK, Epi LASIK, cataract, glaucoma, keratoconus- corneal collagen crosslinking.


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