**Core Concept**
LASIK (Laser-Assisted In Situ Keratomileusis) is a type of refractive surgery used to correct vision problems such as nearsightedness, farsightedness, and astigmatism. The procedure involves creating a thin flap in the cornea, which is then lifted and reshaped with an excimer laser.

**Why the Correct Answer is Right**
The primary contraindication for LASIK is thin corneas, which are often associated with conditions such as keratoconus. Patients with thin corneas may not be suitable candidates for LASIK due to the risk of flap complications and corneal perforation. This is because the cornea is the primary structure responsible for maintaining the shape of the eye, and any significant thinning can compromise its integrity.

**Why Each Wrong Option is Incorrect**
* **Option A:** Dry eye syndrome is a common complication of LASIK, but it is not a contraindication. Patients with dry eye syndrome may still undergo LASIK, but they may require additional treatments to manage their symptoms.
* **Option B:** High myopia (nearsightedness) is not a contraindication for LASIK. In fact, LASIK is often used to correct high myopia in patients who are not candidates for other types of refractive surgery.
* **Option C:** Astigmatism is a common condition that can be corrected with LASIK. In fact, LASIK is often used to correct high levels of astigmatism in patients who are not candidates for other types of refractive surgery.

**Clinical Pearl / High-Yield Fact**
Patients with thin corneas or other corneal abnormalities should undergo a thorough evaluation before undergoing LASIK to determine their suitability for the procedure.

**Correct Answer:** D