The improvement of the visual acuity and protection of the eye is the main purpose of wearing spectacles. It was not until in 1270 that it was introduced to the people and at that time only the plus lens was utilized for presbyopia.
Specific spectacles is regarded, in this report, as indicating those whose application improves the visual acuity and those used for myopia, hyperopia. astigmatism, and presbyopia are excluded.
Some of these specific spectacles are introduced here.
1. Hemianopsia spectacles.
2. Ambryopic spectacles (Low vision aids)
3. Ptosis Crutch spectacles.
4. Phakic-aphakic (P-A) spectacles.
5. Fresnel membranous lenses.
6. Varilux lenses.
7.Spectacles for widening restricted visual fields.
8. Contact lenses.
9. Pseudophakia (Binkhorst lenses)
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