what if NRA/PRA give (-)number, do you reduce the ADD?

[pk916]

Hi

I'm used to when refine the ADD with NRA/PRA when the total is positive number
When you have NRA/PRA give (-)number, do you reduce the ADD?

ex. +0.50/-1.50 = this is -1.00 then divide by 2 is = -0.50
if the base ADD is +1 then would final add be +0.50?

I never thought that reducing an ADD is a thing but I can't remember nra/pra quite well

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[Snakedoctor1]

I've never been a fan of this method of determining add power. Some may disagree but I find it much more beneficial to be as practical about the add as possible. Find out what they are going to use it for and try to recreate it in the exam room. Sometimes I use loose lenses and have the patient sit in front of my computer and mimic whatever their work/home situation is and we trial it.

It's also quite likely you'll get just as accurate of a result if you simply base it on the patient's age. If we're talking about a kid, I don't advocate adds unless you get some clear subjective benefit (in which case there is usually wiggle room due to accommodative ability) or a measurable improvement in binocular alignment/stereopsis in cases of accommodative esotropia.

If you're asking because you're a student about to take a test, then I think you have it right but honestly I don't remember...

 

[pk916]

I've never been a fan of this method of determining add power. Some may disagree but I find it much more beneficial to be as practical about the add as possible. Find out what they are going to use it for and try to recreate it in the exam room. Sometimes I use loose lenses and have the patient sit in front of my computer and mimic whatever their work/home situation is and we trial it.

It's also quite likely you'll get just as accurate of a result if you simply base it on the patient's age. If we're talking about a kid, I don't advocate adds unless you get some clear subjective benefit (in which case there is usually wiggle room due to accommodative ability) or a measurable improvement in binocular alignment/stereopsis in cases of accommodative esotropia.

If you're asking because you're a student about to take a test, then I think you have it right but honestly I don't remember...

Thank you so much for the clarification and the advice on real life as well !!

 

[Inharmonious]

I've never been a fan of this method of determining add power. Some may disagree but I find it much more beneficial to be as practical about the add as possible. Find out what they are going to use it for and try to recreate it in the exam room. Sometimes I use loose lenses and have the patient sit in front of my computer and mimic whatever their work/home situation is and we trial it.

It's also quite likely you'll get just as accurate of a result if you simply base it on the patient's age. If we're talking about a kid, I don't advocate adds unless you get some clear subjective benefit (in which case there is usually wiggle room due to accommodative ability) or a measurable improvement in binocular alignment/stereopsis in cases of accommodative esotropia.

If you're asking because you're a student about to take a test, then I think you have it right but honestly I don't remember...

This right here. I ask about working distance and what function they need help with. If it's a jeweler that works at 30 cm, then you'll need a higher ADD, if it's someone that is working with a screen 60cm away then you'll need lower. I start with an age based ADD and then adjust from there for the patients specific needs.