An Ophthalmologist Diagnosed as A ‘simple myopia with regular astigmatism’. Which of following glasses to be prescribed?
**Core Concept**
Myopia with regular astigmatism is a type of refractive error where the eye has a spherical curvature in the anterior-posterior axis and a cylindrical curvature in the horizontal or vertical axis, resulting in blurred vision at near and far distances. To correct this, a cylindrical lens with a certain axis and power is required to neutralize the astigmatism.
**Why the Correct Answer is Right**
The prescription for myopia with regular astigmatism involves a cylindrical component to correct the astigmatism. The axis of the cylinder is typically aligned with the steepest meridian of the cornea, which can be determined by keratometry or subjective refraction. In this case, the Ophthalmologist has diagnosed simple myopia with regular astigmatism, indicating that the prescription should include a cylindrical component with a specific axis and power.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the cylindrical component necessary to correct the astigmatism.
**Option B:** This option is incorrect because it does not provide the necessary axis for the cylindrical lens, which is crucial for correcting the astigmatism.
**Option C:** This option is incorrect because it specifies a spherical power without a cylindrical component, which would not correct the astigmatism.
**Clinical Pearl / High-Yield Fact**
When prescribing glasses for myopia with regular astigmatism, the axis of the cylinder is critical to ensure proper alignment with the steepest meridian of the cornea. A common mnemonic to remember the axis is "180 minus the degree of the patient's age in years," but this should not be relied upon as the sole method of determining the axis.
**Correct Answer:** C.