Take 50 point Q: choose the best correct answer .
1. During the treatment of hyperopia with PRK, the curvature of the anterior corneal surface must A: be flattened. B: remain unchanged. C: be steepened.
2. Er:YAG lasers are not suitable for the treatment of caries because of A: cytotoxicity. B: low efficiency. C: thermal effects.
3. Angioplasty with excimer lasers is likely to induce A: atherosclerosis. B: restenosis. C: thermal injury.
4. In stapedotomy with Er:YAG lasers, the fluence should be limited to A: 1 J/cm2. B: 10 J/cm2. C: 100 J/cm2. 5. The deepest layer of the skin is called: A: dermis. B:epidermis. C: subcutis. D: fat tissues​