The wavelength of laser (in nanometers) for shaping cornea in refractive surgery is –
**Core Concept**
The question requires knowledge of the specific wavelength of laser used in corneal reshaping during refractive surgery. The correct answer is related to the principle of selective absorption of light by the corneal tissue, which allows for precise removal of tissue without damaging surrounding areas.
**Why the Correct Answer is Right**
The most commonly used wavelength for this purpose is 193 nanometers (nm), which corresponds to the ultraviolet (UV) spectrum. This wavelength is selectively absorbed by the corneal tissue, allowing for precise ablation of the corneal surface. The 193 nm wavelength is generated by excimer lasers, which are widely used in refractive surgery procedures such as LASIK (Laser-Assisted In Situ Keratomileusis).
**Why Each Wrong Option is Incorrect**
**Option A:**
This option is incorrect because it is not the correct wavelength used in corneal reshaping. The 1064 nm wavelength is typically associated with Nd:YAG lasers, which are used for other ophthalmic applications such as posterior capsulotomy.
**Option B:**
This option is incorrect because the 532 nm wavelength is typically associated with green light, which is not selectively absorbed by corneal tissue in the same way as the 193 nm wavelength.
**Option C:**
This option is incorrect because there is no widely used laser application in ophthalmology that corresponds to a 780 nm wavelength.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the 193 nm wavelength is specifically designed for corneal reshaping, and its selective absorption by corneal tissue allows for precise tissue removal without damaging surrounding areas.
**Correct Answer:** C. 193 nanometers.