Conjunctival xerosis is seen in –
**Core Concept**
Conjunctival xerosis refers to the dryness of the conjunctiva, the thin membrane covering the white part of the eyes and the inner eyelids. This condition is often associated with tear film instability and is a common symptom of various ocular surface disorders.
**Why the Correct Answer is Right**
Conjunctival xerosis can result from a deficiency in tear production, which can be due to various factors such as Sjögren's syndrome, dry eye syndrome, or vitamin A deficiency. The conjunctiva is lined by a stratified non-keratinized epithelium, and its dryness can lead to discomfort, blurred vision, and increased sensitivity to light. The lacrimal gland, located under the eyebrow, produces tears that help to lubricate the conjunctiva and maintain its health.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because conjunctival xerosis is not typically associated with conjunctival inflammation, such as conjunctivitis. While conjunctivitis can cause discomfort and redness, it is not characterized by dryness of the conjunctiva.
**Option B:** This option is incorrect because conjunctival xerosis is not a direct result of corneal scarring. Corneal scarring can be caused by various factors, including trauma, infection, or degenerative conditions, but it does not directly contribute to the dryness of the conjunctiva.
**Option C:** This option is incorrect because conjunctival xerosis is not typically associated with a decrease in corneal sensitivity. Corneal sensitivity is an important aspect of ocular health, and its decrease can be a symptom of various conditions, but it is not directly related to conjunctival dryness.
**Clinical Pearl / High-Yield Fact**
Conjunctival xerosis is often associated with a decrease in tear breakup time, which can be measured using a Schirmer test. This test involves placing a strip of filter paper under the eyelid to measure the amount of tears produced and the time it takes for the tears to break up.
**Correct Answer:** D. Vitamin A deficiency.