Contraindication of LASIK –
**Core Concept**
LASIK (Laser-Assisted In Situ Keratomileusis) is a refractive surgical procedure used to correct vision problems such as nearsightedness, farsightedness, and astigmatism by reshaping the cornea. The procedure involves creating a thin flap in the cornea, which is then lifted to allow the excimer laser to reshape the underlying tissue.
**Why the Correct Answer is Right**
A significant contraindication of LASIK is **keratoconus**, a progressive eye disease characterized by thinning and conical deformity of the cornea. Patients with keratoconus have a weakened cornea that cannot support the creation of a stable flap during LASIK, which may lead to flap complications, vision loss, or even corneal perforation.
**Why Each Wrong Option is Incorrect**
**Option A:** **Dry eye** is not a contraindication for LASIK, although it may be a complication of the procedure. Patients with dry eye can still undergo LASIK, but they may require additional treatments to manage their dry eye symptoms.
**Option B:** **Presbyopia** is a normal age-related condition that affects the lens of the eye, causing difficulty in focusing on close objects. LASIK is not a treatment for presbyopia, but it can be used to correct other vision problems that may coexist with presbyopia.
**Option C:** **Hypertension** is not a contraindication for LASIK, although patients with uncontrolled hypertension may require additional medical clearance before undergoing surgery.
**Option D:** **Asthma** is not a contraindication for LASIK, but patients with asthma may require additional medical clearance before undergoing surgery, especially if they have a history of respiratory complications.
**Clinical Pearl / High-Yield Fact**
Remember that LASIK is not a cure for all vision problems, and patients may still require glasses or contact lenses for near vision after the procedure.
**Correct Answer: D. Asthma is not a contraindication for LASIK, but patients with asthma may require additional medical clearance before undergoing surgery.**