subjective binocular refraction

what are the advantages of a binocular refraction in comparison to a monocular refraction and binocular balancing (5)

• Greater relaxation of accommodation - hyperopic – constantly accommodating

• Light adaptation equal

• 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.

• In a latent nystagmus patient ,the occlusion in monocular refraction may cause the nystagmus to manifest.

what types of px’s is SBR ideal on (3)

• Latent Hypermetropes.

• Pseudomyopes – accommodation has gone into spasm – present as a myopic patient

• Latent nystagmus

what px’s are a contraindication to SBR (3)

• px’s who don’t have a BV

• Good idea to do worth 4 dot test before binocular refraction (t0 see if they gave BV)

• may be difficult to do on px who have an imbalance in VA between the 2 eyes

explain the procedure for SBR (6)

• 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.