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Borish delayed test procedure and its indications

 Borish delayed test was performed to rule out the following:

·         overcorrected myopia

·         under corrected hyperopia

·         to control maximum accommodation.

Procedure

·         Perform the regular monocular subjective refraction using the standard steps of subjective acceptance to provide the best monocular visual acuity.

·         Subjective correction is to put in trial frame

·         The patient should instruct to look at the near visual acuity target one line above the best corrected visual acuity at a testing distance of 40cm.

·         Perform NRA (Negative Relative Accommodation) measurement by adding plus lenses binocularly in 0.25 DS steps until the patients reports “sustained blur”.

·         Direct the patient’s attention to the previously read best corrected distant visual acuity line.

·         Defog binocularly in 0.25 DS steps until the patient is able to read the best corrected distant visual acuity line.

·         After adequate adaptation binocularly, depending on the patient’s comfort the final correction can be decided by adding the previous subjective refraction value and the left-out power after performing binocular defogging.

·         E.g., for a patient subjective refraction at the initial stage is OD: +2.00DS and for OS: +2.50 DS. After performing NRA we got +3.00 DS NRA value for both the eye. After performing binocular defogging the left-out power is +0.50 OU. In case with this power after the binocular adaptation patient is able to perceive a comfortable distance visual acuity as per the previous subjective refraction at the initial stage. Then the final prescription for this patient should be for OD: +2.50DS and for OS: +3.00 DS.

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