8.3 Prescribing Spectacles
The Objectives of Treatment:
- Good vision in each eye
- Good alignment
- Comfort
1. Cycloplegia
- Younger than 12 months of age – cyclopentolate 0.5% ± phenylephrine 2.5%
- Older than 12 months of age – cyclopentolate 1.0% ± alcaine ± phenylephrine 2.5%)
- If this is not successful, consider atropine refraction from 1 to 5 years of age (instil one drop twice a day, for 3 days prior to the appointment)
2. Prescribing Spectacles For:
i. Amblyopia (Ensure Full Time Wear of Glasses)
- Add plus / minus spheres (as accommodation is not an issue) to maximise visual acuity, asking “Do you prefer lens 1 or 2” etc
Isometropia
- Astigmatism > + 1.50D
- Hypermetropia > + 4.00D
Anisometropia
- Astigmatism > + 1.50D
- Hypermetropia > + 1.50D
- Myopia > - 3.0D
ii. Esotropia (Ensure Full Time Wear of Glasses)
- Fully correct the hypermetropia (do NOT take off any for cycloplegia)
- Fully correct anisometropia
- Fully correct astigmatism (adults won’t tolerate a large change in astigmatic correction)
- If there is a high AC/A ratio, add + 3.0D bifocal with an executive lens bisecting the pupil or a short corridor, wide reading zone multifocal lens
iii. Hypermetropia (No Esotropia)
- Under correct hypermetropia by approximately +2.0D
- Fully correct anisometropia
- Fully correct astigmatism
iv. Astigmatism
- Under-correct hypermetropia (kids do NOT like full plus correction)
- Consider giving minus overcorrection if subtracting 2.0D changes the sphere from plus to minus
- Fully correct anisometropia
- Fully correct astigmatism
v. Myopia
- Fully correct myopia
- Fully correct anisometropia
- Fully correct astigmatism
3. Management of a Squint
- Glasses, Patching, Orthoptic Exercises, Surgery
4. Follow-Up
- Check glasses are made correctly
- Don’t panic when the VA is poorer. Fully corrected hypermetropes may record worse at their first visit following spectacle prescription and it is wise to counsel patients and their parents about this at the time of prescribing glasses. Astigmatic patients take time for vision to improve
- Don’t try subjective refraction in younger children under 7 or 8 years of age or in an amblyopic eye. Only consider it once they can read the Snellen chart well
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