plus minus technique

• 1. occlude left eye and measure unaided vision
• 2. direct the patients attention to their best visual acuity line
• 3. always offer positive lenses
• 4. if vision is better than 6/12 use +0.25 steps and if it is worse than 6/12 use 0.5DS steps and ask if the letter is clearer, worse or the same with the lens

  5. if the lens blurs the visual acuity don’t add it
• 6. if acuity remains the same or improves then change the lens in the trial frame with one +0.25DS more
• 7. continue adding plus lenses in 0.25DS until the vision gets worse
• 1. if vision blurs with a +0.25 lens hold a -0.25 lens and ask if it is clearer with or without it or if there is no difference.
  2. if the patient reports improvement and there is improvement in vision add -0.25DS
  3. if there is reported improvement but there is no improvement in vision ask if the letters look clearer or smaller and blacker
  4. if smaller and blacker don’t add the -0.25DS
• 12.stop adding negative lenses when the patient sees the same or smaller or bigger