Microlaryngoscopy is usually done with an objective lens with focal length of
**Core Concept**
Microlaryngoscopy is a technique used in otolaryngology for the examination of the laryngeal structures. The procedure requires a specialized microscope with an objective lens that provides a clear and magnified view of the larynx.
**Why the Correct Answer is Right**
The objective lens used in microlaryngoscopy typically has a focal length of 300-400 mm. This focal length allows for a high level of magnification, usually between 4-8 times, while maintaining a comfortable working distance for the surgeon. The lens is designed to provide a clear and detailed view of the laryngeal structures, including the vocal cords, glottis, and surrounding tissues.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is likely incorrect because the focal length of 200 mm would result in insufficient magnification for accurate examination.
**Option B:** This option may be incorrect because the focal length of 500 mm would result in too much magnification, making it difficult to maneuver surgical instruments.
**Option C:** This option is likely incorrect because the focal length of 100 mm would result in too low a level of magnification, making it difficult to visualize the laryngeal structures.
**Clinical Pearl / High-Yield Fact**
It's essential to note that the choice of objective lens focal length may depend on the specific surgical procedure being performed and the surgeon's personal preference. However, a focal length of 300-400 mm is generally considered standard for microlaryngoscopy.
**Correct Answer:** C.