**Core Concept**
Higher-order aberrations refer to distortions in the optical wavefront that occur in the eye due to irregularities in the cornea or lens. These aberrations result in a non-uniform distribution of light, leading to symptoms such as halos, glare, and decreased visual acuity.

**Why the Correct Answer is Right**
Higher-order aberrations include coma, trefoil, and spherical aberration, among others. These aberrations occur due to irregularities in the shape of the cornea or lens, which can be caused by conditions such as keratoconus, pellucid marginal degeneration, or surgical complications. The correct answer refers to a type of aberration that is not considered a higher-order aberration.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it is actually a type of higher-order aberration. Coma is a common type of higher-order aberration that occurs due to irregularities in the shape of the cornea or lens.
* **Option B:** This option is incorrect because it is also a type of higher-order aberration. Trefoil is a type of higher-order aberration that can cause significant visual disturbances.
* **Option D:** This option is incorrect because it is a type of lower-order aberration, not a higher-order aberration. Myopia is a refractive error that can be corrected with glasses or contact lenses, but it is not a type of higher-order aberration.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that higher-order aberrations can significantly impact visual quality and can be corrected with specialized contact lenses or refractive surgery.

**Correct Answer: C. Myopia**