Subjective refraction final
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Basic subjective refraction for optometry, ophthalmology, ophthalmic technicians. Talk developed and given in 2016 to back office technicians in a 9 location ophthalmology practice consulting client to improve refraction outcomes.
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Subjective refraction final
- 3. What is Refraction? ■ Determination of the refractive status (prescription) of the eye. OBJECTIVE Retinoscopy Autorefraction SUBJECTIVE Subjective Refraction Phoropter Epic
- 4. Subjective Refraction ■ To determine by subjective means the combination of spherical and cylindrical lenses necessary to to provide best visual acuity. ■ (with accommodation relaxed)
- 5. Principles of Refraction 1. Accommodation-relaxed state 2. Maximum PLUS, minimum minus
- 6. Principles of Refraction When can we ignore accommodation?
- 7. How can we be sure accommodation is relaxed? ■ Use PLUS lens to FOG ■ Ensure image is located in front of retina ■ This causes image / VA to become worse if eye attempts to accommodate (Image point becomes further away from the fovea)
- 8. Two sets of commonly used instruments
- 9. Start from Auto-Ref Results (OD) 1. Best Vision Sphere 2. Jackson Cross Cylinder 3. Best Vision Sphere Repeat 1-3 on OS 4. Binocular Balancing 5. Binocular Best Sphere OU Steps in Subjective Refraction
- 10. Fogging ■ Place enough PLUS lenses to FOG vision to 20/40 line ■ Pointer: every line is about 0.25 diopter ■ Slowly reduce the plus power until best vision ■ Remember: “Maximum plus power for best visual acuity”
- 11. Astigmatism
- 12. Step 2:JacksonCrossCylinder ■ JCC used to find used to determine the cylindrical axis and the cylindrical power for the patient. Yes, we have these!
- 13. Step 2: JCC ■ JCC used to find used to determine the cylindrical axis and the cylindrical power for the patient.
- 16. How can we be sure accommodation is relaxed? ■ Use PLUS lens to FOG ■ Ensure image is located in front of retina ■ This causes image / VA to become worse if eye attempts to accommodate (Image point becomes further away from the fovea)
- 20. Cylinder Power ■ Patient directed to observe a round target ■ Align red lines OR white lines to trial lens axis
- 23. Cylinder Power ■ If view one is clearer, ADD +0.25 cylinder power
- 24. Steps in Subjective Refraction Start from Auto-Ref Results (OD) 1. Best Vision Sphere 2. Jackson Cross Cylinder 3. Best Vision Sphere Repeat 1-3 on OS 4. Binocular Balancing 5. Binocular Best Sphere OU
- 25. Fogging like before... ■ Use PLUS lens to FOG ■ Ensure image is located in front of retina ■ This causes image / VA to become worse if eye attempts to accommodate (Image point becomes further away from the fovea)
- 26. What about for reading? I'm over 40 years old and I can't read my phone. What's that from?
- 27. Near Addition ■ Presbyopic patients would require a near addition for their reading.
- 28. Finding the Near Addition ■ Step 1: Estimation from patient’s age + 1.00 + 1.50 + 2.00 + 2.25 + 2.50 40 - 45 46 - 50 51 - 55 56 - 65 65+ Age Estimated Add
- 29. Finding the Near Addition ■ Step 2: Place the estimated near addition on top of the distance prescription ■ Step 3: Put near chart at 40 cm or 16” on near point rod and attach to phoropter.
- 30. Finding the Near Addition ■ Optional stuff after this!
- 31. Range of clear vision 20CM 60CM 40CM ■ Patient’s habitual reading distance in the middle of the range of clear vision.
- 32. Range of clear vision 10CM 50CM 40CM ■ If range is too close to patient: Add -0.25DS in steps
- 33. Range of clear vision 30CM 70CM 40CM ■ If range is too far to patient: Add +0.25DS in steps