independent subjective refraction

Advantages of a binocular refraction compared to monocular refraction

• Greater relaxation of accommodation.

• Light adaptation equal.

• Generally , the eye is in a more “normal” situation than when one eye is occluded . (care must be taken the cyl axis is not incorrect as this will create an unnatural visual axis)

• Can be slightly quicker than monocular refraction , because no binocular balancing is required.

which patients are ideal for binocular refraction

1. latent hypermetropes

2. pseudometropes

3. latent nystagmus

what is the procedure for subjective binocular

• With the retinoscopy result in place measure the visual acuity.

• Occlude the right eye and blur the left eye, using +0.75DS or +1.00 DS . Check this blurs the vision (usually 3-4 lines on the chart) Remove the occlude.

• Find BVS, and then check cyl axis and power using the JCC method. Use Duochrome to determine the best sphere endpoint.

• Measure the VA and record this. Remove the fogging lens in the left eye and place this in front of the right eye .

• Find BVS for left eye, and then check cyl axis and power using the JCC method. Use Duochrome to determine the end result sphere.

• Measure the VA and record this.

how much vergance is induced by moving the chart from 6m to 3m

-0.30 D

is duochrome binocular or monocular

monocular

use duochrome after what acuity is reached

6/12 acuity

what is the stenopic slit used for

a 1-2 mm slit in an ocluder used to identify astigmatism axis

what is the method for stenopeic slit

1. patient wears it in trial frame

2. occluded other eye

3. display 6/18 or 6/24

4. patient rotate till clear