Distinguish conjunctivitis from keratitis.

Distinguish conjunctivitis from keratitis.

• A. Keratitis is corneal inflammation causing pain, photophobia, and decreased vision; conjunctivitis is conjunctival inflammation with redness and discharge
• B. Conjunctivitis is conjunctival inflammation with redness and discharge; keratitis is corneal inflammation causing pain, photophobia, decreased vision
• C. Conjunctivitis causes severe eye pain; keratitis has no pain
• D. Conjunctivitis involves the lens

Answer: (B)

The key idea is where the inflammation is happening. Conjunctivitis involves the conjunctiva, so the classic signs are redness and discharge with irritation, while vision is usually preserved and pain is mild. Keratitis involves the cornea, and because the cornea is highly innervated, it produces notable pain, photophobia, tearing, and often a drop in vision. In practice, if a patient has a red eye with discharge but significant pain, light sensitivity, and decreased vision, you should suspect keratitis; if the eye is red with discharge and minimal pain with preserved vision, conjunctivitis is more likely.

The key idea is where the inflammation is happening. Conjunctivitis involves the conjunctiva, so the classic signs are redness and discharge with irritation, while vision is usually preserved and pain is mild. Keratitis involves the cornea, and because the cornea is highly innervated, it produces notable pain, photophobia, tearing, and often a drop in vision. In practice, if a patient has a red eye with discharge but significant pain, light sensitivity, and decreased vision, you should suspect keratitis; if the eye is red with discharge and minimal pain with preserved vision, conjunctivitis is more likely.