**Question:** A soft contact lens users have corneal keratitis cause is –

A. inadequate lens care
B. poorly fitted lenses
C. excessive lens wear time
D. frequent lens exchange

**Core Concept:** Corneal keratitis is an inflammation of the cornea, the transparent tissue covering the front part of the eye. This condition is often associated with the use of soft contact lenses, as the lens can act as a nidus for microbial invasion and can impede the cornea's natural defense mechanisms.

**Why the Correct Answer is Right:** Corneal keratitis in soft contact lens users is primarily caused by inadequate lens care (option A). Inadequate lens care can lead to a range of complications, including microbial contamination, biofilm formation, and microbial keratitis. Soft contact lenses provide a suitable environment for microbes to colonize and multiply, increasing the risk of infection.

**Why Each Wrong Option is Incorrect:**

B. Poorly fitted lenses (option B) can cause discomfort and abnormal tear film distribution, but this is not the primary cause of corneal keratitis. Inadequate lens care is more likely to lead to microbial colonization and infection.

C. Excessive lens wear time (option C) can exacerbate the condition, but it is not the direct cause of corneal keratitis. Inadequate lens care is more likely to introduce pathogens onto the lens surface, leading to infection.

D. Frequent lens exchange (option D) may help alleviate discomfort and maintain lens transparency, but it does not prevent microbial keratitis. Inadequate lens care remains the primary cause of corneal keratitis, as it facilitates microbial colonization and infection.

**Clinical Pearl:** Proper soft contact lens hygiene is essential to prevent corneal keratitis, as well as other complications associated with contact lens use. This includes regular lens replacement, thorough cleaning, disinfecting, and following the manufacturer's guidelines for lens wear. If keratitis occurs, prompt removal of the lens, appropriate antibiotic treatment, and expert consultation are crucial for successful recovery.