Article taken from Mark E Wilkinson, OD
Plus Cylinder Subjective Refraction Techniques for Clinicians
January 2016
UIHC Department of Ophthalmology and Visual Sciences
General Refraction Techniques
Prescribing Glasses
Question: What do you check when a patient complains that their new glasses are not as
good as their previous pair?
Answer:
1. Ask specifically what the complaint is. Distance? Near? Asthenopia? Diplopia?
Pain behind the ears or at the bridge of the nose from ill-fitting glasses?
2. Read the new and old glasses on the lensometer and compare.
3. If you feel the RX is reading different than prescribed on an automated lensometer,
check the RX on a manual lensometer to be sure.
Mark E Wilkinson, OD Plus Cylinder Subjective Refraction Techniques for Clinicians
January 2016
UIHC Department of Ophthalmology and Visual Sciences
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4. Remember that digital lenses, particularly digital progressive lenses will not measure
exactly to the power prescribed. This is because digital lenses are designed to adjust
for the different vertex distances the patient will have when viewing through different
parts of the lens.
5. Make sure the old glasses did not have any prism.
6. Check the patient for undetected strabismus with cover testing.
7. Refract the patient again. Possibly, with a cycloplegic agent, if the symptoms
warrant.
8. Check the optical centers in comparison with the pupillary centers.
9. Check whether the reading segments are in the correct position.
10. Make sure the new glasses fit the patient correctly.
11. Check whether the old glasses were made in a plus cylinder design using the Geneva
lens clock.
12. Check whether the base curve was changed using the Geneva lens clock.
13. Evaluate the patient for dry eyes.
14. If the patient has a high prescription, check the vertex distance. Often is it easier to
refract such patients over their old pair of glasses to keep the same vertex distance.
15. Check the pantoscopic tilt. Normally the tilt is 10-15 degrees so that when the patient
reads, the eye is perpendicular to the lens. If the tilt is off, especially in relation to the
old glasses, the patient may be noticing this change.
16. With postoperative glasses, evaluate for diplopia in down gaze due to anisometropia.
17. Perhaps the add is too strong or too weak. Check the patient using trial lenses and
reading material.
18. Sometimes if the diameter of the lens is much larger in the newer frame, the patient
may be noticing distortion in the periphery of their lenses. In this situation,
encourage a smaller frame. Conversely, if the new frame is significantly smaller, the
patient may notice the edges of the lenses or, the reading area of their multifocal lens
may be too small to use efficiently. In this situation, encourage a larger frame.
19. Above all, try to test the new prescription in a trial frame with a walk around the
office; you do not want to go through this process again.
References:
Mark E Wilkinson, OD Plus Cylinder Subjective Refraction Techniques for Clinicians
January 2016
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