Hi, today we are going to perform negative relative accommodation for that a person has to be fully corrected for the refractive error and the distance for the test has to be 40 centimeter and the target what we give is the one line above the base corrected visual equity. For her the visual equity is N6 so we will be asking her to read N8 so are you able to see that? Okay, so I'll make certain changes in front of your eyes and you it may get blur, but you have to keep trying to make it clear.
Let me know when you are not able to make it clear when you achieve a sustained blur. This NRA test is performed using flash lens. We have to gradually increase the power of the lens till the patient's reports sustained blur.
Also make sure that you are placing the next lens before removing the previous lens. The expected value for NRA is plus 2.50 and the higher NRA values indicates uncorrected hyperopia or overcorrected myopia. For example, if you are getting NRA value of 3.5 diopter, it indicates that if patient was hyper-opped then it was undercorrected with 1 diopter.
or if she was myope then the myopia was over corrected with minus 1 diopter similarly if you are getting nra lesser than 2.5 for example if nra is plus 1 it indicates that the myopia was under corrected with minus 1.5 diopter or hyperopia was over corrected with 1.5 Next step is to gradually defog this power. You have to place the next lens before removing the previous one. Next we are going to perform positive relative accommodation.
The target again should be 40 cm and trial frame should be adjusted. Patient has to be fully corrected for the refractive error. And this test we start with the minus lenses.
So first lens which I'm going to put is the minus 0.25 and I'll remove this lens and then I'll put the another lens of higher values. So next lens will be 0.50. So make sure that you are removing the lens first and then keeping the other lens.
So I'll keep on increasing till the patient starts reporting blur. the normal expected value for pra is minus 2.5 diopter you may get a value even higher than 2.5 but if you are getting the values lesser than 2.5 it may indicates binocular vision anomalies especially the virgins and accommodative problems so now again i'll reduce these values you have to remove the value first and insert the lens with the lesser power. So from 2.5 I have put 2 and you have to reduce till 0.