Binocular balancing

3rd Year Student Of Optometry at ISRA School Of Optometry

1. Binocular Balancing Sahira tayyab Bsvs 3 rd year

2. Binocular balancing The final important step of subjective refraction is to make certain that accomadation has been relaxed equally in the 2 eyes is known as binocular balancing. PURPOSE : To Equalize accommodation between the two eyes Not to equalize the best corrected visual acuity between the two eyes: CANNOT BE PERFORMED WHEN : px suppresses one eye strabismus exists px has only one eye

3. Why? Pre- presbyopic patients can accommodate during the distance monocular refraction Patients may actually accommodate different amounts in the left and right eyes

4. Methods for binocular balance technique : There are various methods that may be employed to perform binocular balancing of a prescription . These include : 1 Successive Alternate Occlusion 2Vertical Prism Dissociation 3Blurring or fogging ( Humphriss Immediate Contrast) 4 Polarized or Vectographic 5 Turville Infinity Balance (Septum technique)

5. 1.Successive Alternate Occlusion: Procedure: ADD plus lenses binocularly till px barely sees 20 /50 line(6/18) over the Rx you just achieved from the monocular subjective refraction examiner performs slow alternate occlusion Px compares of letters between 2 eyes “I know this is blurry, I want you to tell me which image is clearer, or are they both equally blurred.” END POINT end point is equal acuity b/w 2 eyes If one eye clearer than Plus lenses added in + 0.25DS steps before clearer eye to equalize the blur

6. 2.Vertical Prism Dissociation: Procedure : The two eyes will be dissociated by using the prisms in the technique Same amount of fog as last technique +1.00 Same isolated line used 20/50 Keep the prisms of 3 or 4 Δ BD in OD and 3 or 4 Δ BU in OS Equal and opposite BD prism will cause image to be higher (top) The image will be displaced towards the apex (point) of the prism Δ BU prism will cause image to be lower (bottom) BD for OD and BU for OS, therefore; EGNU5 seen by OD EGNU5 seen by OS

7. Cont’d…!!! Patient instructions : “I know these images are blurred, I want you to take a few seconds and look at the image on the top, and then take a few seconds and look at the image on the bottom, tell me is one image clearer or are they equally blurred?” If the patient reports the top image clearer, add +0.25DS to the OD and repeat the question If the patient reports the lower image clearer add +0.25DS to the OS and repeat the question Now px report both eyes see blur it means we balance the accommodation with +0.25DS At the end remove prism and fog lenses that are use for the balancing and correct the lenses

8. 3.Fogging method / humphriss immediate contrast test: Procedure: Place +0.75DS/+1.00DS fogging lens before the LE Fogging verified lens should blur 3_4 lines on chart Present +0.25DS lens ( lens 1)over RE , replace with _0.25DS lens (lens2)and once again revert to +0.25DS (lens1) Px asked to compare lenses 1 2 and 1 Px must report which lens makes target clearer sharper and comfortable to look If px reports lens 2 better then add _0.25DS lens Present lenses 1 2 and 1 again END POINT: Px reports view through both lenses is the same Reversal Once RE Rx balanced fog RE and perform procedure on LE

9. 4.Polaroid Technique /( Vectographic ) Polaroid Filters are used to partially dissociate the two eyes FZBD FZBD While wearing polaroid filters (P in phoropter knob), each eye sees a separate line and the rod in the middle serves as a fusion lock

10. Polaroid Technique Fog by +1.00 OD and OS Same technique as the vertical prism dissociation Make appropriate adjustments Most natural binocular balance technique as diplopia and prism are not introduced

11. 5.Septum Technique: Separate the visual fields with a septum in the refracting lane Each eye sees part of the line Fog by a +1.00 DS Same instruction set as vertical prism dissociation

12. Reference : American academy Zadnik Internet Notes