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Hede the lensese are preferred because specs are thicker or lens are??
Your notes say spectacles (glasses) are thicker - and that's exactly WHY soft contact lenses are preferred in high myopia.
Here's the logic clearly:
In High Myopia - Why Contact Lenses (Soft Lenses) are Preferred over Specs
High myopia requires high-powered concave (diverging) lenses with strong negative power.
When you make a high-power concave lens for spectacles:
- The glasses become very thick (especially at the edges)
- They cause significant image minification - objects appear smaller than they really are (this is called "minification" because concave lenses reduce image size)
- This is uncomfortable, cosmetically unpleasant, and visually distorting
So soft contact lenses are preferred in high myopia because:
| Problem with Specs | How Contacts Help |
|---|---|
| Thick lenses (high power = thick edges) | Contacts sit on the eye - thinness is not an issue |
| Image minification | Much less minification with contacts |
| Heavy and uncomfortable | Lightweight, sits on cornea |
| Prismatic aberrations at edges | Contacts move with the eye, no edge distortion |
To directly answer your question:
Spectacle lenses are thicker (in high myopia) - and BECAUSE they are thick AND cause image minimization, contact lenses are preferred instead.
So the answer from your notes is: Specs are thicker → that's the reason to switch to soft lenses. ✓
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