Prolonged use of topical ocular decongestants is known to cause what effect?

• A. Conjunctival scarring
• B. Preservative toxicity
• C. Rebound hyperemia
• D. Corneal edema

Answer: (C)

Prolonged topical ocular decongestant use leads to rebound hyperemia because these drugs are vasoconstrictors of the conjunctival vessels, and with frequent use the ocular surface develops tachyphylaxis or receptor downregulation. As a result, the vasoconstrictive effect wanes, and when the drops wear off the vessels dilate again, often more than baseline, producing redness that returns or worsens—this is the rebound redness. This cycle can continue with ongoing use and then withdrawal. While preservatives in preserved formulations can cause surface toxicity with long-term use, and other issues like corneal edema or scarring aren’t the typical rebound effect, the classic and most expected consequence after extended use is rebound hyperemia.