Uploaded byMohammad Arman Bin Aziz
Binocular balance (review)
1. The document discusses different techniques for binocular balance testing including vertical prism dissociation, successive alternate occlusion, blurring technique, and binocular refraction. 2. Vertical prism dissociation uses prisms placed before each eye to equalize the accommodation stimulus and relax accommodation in order to find the point of equal blur between the eyes. 3. The appropriate technique depends on whether the eyes have equal visual acuity and accommodation, with prism dissociated duochrome used if these differ between eyes.
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Binocular balance (review)
- 1. Binocular Balance (Review) MohammadArman Bin Aziz Optometry Officer ICO, CU February 26, 2014
- 2. Types 1. Vertical PrismDissociation 2. Successive alternate occlusion 3. Blurring technique (Humphriss Immediate Contrast) 4. Binocular refraction
- 3. Vertical Prism Dissociation •Purpose: 1.To Equalize the Accommodation stimulus of two eyes. 2.To relax the accommodation of the two eyes.
- 4. Indication •Use only whenboth eyes have equal MSR VA. •If MSR VA and accommodation are different between R and L eye → use Prism dissociated Duochrome.
- 5. Procedure 1. Fogging botheyes +1.00 2. Isolate a line of letters (~20/40) 3. Put 3∆BU over OD and 3∆BD over OS 4. Make sure PT can see 2 lines of letters, if not, Add more Prism equally for both eyes 5. Instruct Pt to compare 2 lines
- 9. Procedure (cont.) 6. Give+0.25 to clearer eye (to blur the eye), until both eyes looks equal (Endpoint) If the clearer eye still looks better after reduce the VA twice (give +0.50) → should give -0.25 to the worse eye (to make the worse eye looks better) 7. After reach the Endpoint → Binocular MPMVA
- 10. Binocular Prism Balance RE(OD) LE (OS) Comment +2.00 +2.25 Initial spheres; VA at monocular endpoints: 20/20 +3.00 +3.25 Fogging OU +1.00 Upper image looks clearer +3.00 +3.50 Equally Blur +3.00 +3.75 Upper image more blur than lower image +3.00 +3.50 Remove prism Start binocular MPMVA Example 1. Balanced at RE +3.00 LE +3.50 . Indicating that the sphere difference should be 0.50D, not 0.25D as suggested by the monocular result → Do the Binocular MPMVA.
- 11. Cont.… RE (OD) LE(OS) Comment -1.25 -2.00 Initial spheres; VA at monocular endpoints: 6/6, 6/6 (partial) -0.25 -1.00 Fogging both eyes +1.00, Lower image clearer Plano -1.00 Lower image still looks clearer +0.25 -1.00 Lower image still looks clearer +0.25 -1.25 Equal Blurred +0.25 -1.50 Upper image looks clearer +0.25 -1.25 Remove prism Start binocular MPMVA Example 2. Balanced at RE +0.25 LE -1.25. → Do the Binocular MPMVA
- 12. If Not ableto balance •Find the Dominat Eye and choose to make the dominat eye clearer. •Use the lenses that provide the closest match.
- 13. Record Binocular Balance +BinocularMPMVA OD +2.00 -1.00 @ 165 VA 20/15 OS +2.00 -1.00 @ 10 VA 20/15
- 14. Prism dissociated Duochrome •If the two eye did not reach equal VA’s during their monocular refractions. • There is reason believe that the • differs in two eye.
- 16. Dissociated Duochrome Test LensesPatient looks at Patient responds Action Monocular end point: OD +1.75D OS + 1.75D Lower image (OD) Red clearer Add -0.25D OD OD +1.50D OS + 1.75D Lower image Red and green equal No change OD +1.50D OS + 1.75D Upper image (OS) Red clearer Add -0.25D OS OD +1.50D OS + 1.50D Upper image Red clearer Add -0.25D OS OD +1.50D OS + 1.25D Upper image Red and green equal No change OD +1.50D OS + 1.25D Lower image Red and green equal (Confirming)
- 17. Successive alternative occlusion •Not use often • Disadvantages: Comparison under monocular condition No peripheral fusion lock Not for hyperopes, anisometropes, nystagmus Pt’s. • Requires occluder
- 18. Procedure • Initial target: 20/50 • Fog +1.00D OU • Compare OD to OS • Ask pt. “which is clearer?” • Give +0.25D to the clearer eye • Endpoint = both eyes most equally clear • Slowly add minus OU > MPMVA
- 20. Blurring technique •Can beused when VA is slightly unequal •Have peripheral fusion lock •Requires Duochrome target •Disadvantages: oNot for hyperopes oNot for everyone is good responder to Duochrome target
- 21. Procedure • Initial target:R/G target • Minimal light • Fog OS by +1.00D • Red-side clear > add -0.25D • Green-side clear > add +0.25D • Endpoint = both sides equal or minimum minus lens > green-side clearer or red-side clear • Fog OD by +1.00D • Unfog OS and perform test (same endpoint criteria as OD) • Fog OS by +1.00D • Slowly add minus OU > MPMVA
- 22. Binocular refraction •Have peripheralfusion lock •More accurately determine cylinder axis •Good for hyperopes, anisometropes, pt. with nystagmus, binocular vision problem. •OD and OS VA’s must be ≥ 20/25 •Performed after retinoscopy
- 23. Procedure • Initial target:appropriate subjective refraction target • Fog OS until VA = 20/50 • Perform subjective refraction (initial sphere, JCC, refine sphere) on OD while OS by +1.00D • Fog OD by +1.00D • Perform refraction on OS • Fog OS by +1.00D • Slowly and minus OU > MPMVA
- 24. References • Primary careoptometry by Theodore Grosvenor • Clinical Procedure of Primary eye care by Davit E. Elliot • Internet