On performing refraction using a plane mirror on a patient who has a refractive error of -3 D sphere with -2 D cylinder at 900 from a distance of 1 metre under no cycloplegia, the reflex would be seen to move
**Core Concept**
The question is testing the understanding of the principles of refraction and the behavior of the retinoscopy reflex in patients with different types of refractive errors. The retinoscopy reflex is used to determine the refractive error of the eye and to assess the presence of any astigmatism.
**Why the Correct Answer is Right**
When performing retinoscopy, the patient is asked to look at an object at a distance. The retinoscopy reflex is projected onto a screen or the examiner's hand. In a patient with a refractive error of -3 D sphere with -2 D cylinder at 90° from a distance of 1 meter, the retinoscopy reflex would move in the direction opposite to the axis of the astigmatism. Since the cylinder axis is at 90°, the reflex would move downward.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option would be incorrect because the reflex would not move upward in a patient with a refractive error of -3 D sphere with -2 D cylinder at 90°.
* **Option B:** This option would be incorrect because the reflex would not move horizontally in a patient with a refractive error of -3 D sphere with -2 D cylinder at 90°.
* **Option D:** This option would be incorrect because the reflex would not move upward and to the right in a patient with a refractive error of -3 D sphere with -2 D cylinder at 90°.
**Clinical Pearl / High-Yield Fact**
It is essential to note that the retinoscopy reflex moves in the direction opposite to the axis of the astigmatism. This is a crucial concept to understand when performing retinoscopy, as it allows the examiner to accurately determine the refractive error and the axis of the astigmatism.
**Correct Answer: C.**