A 32-year-old woman with pain and photophobia in the right eye for a week has worsening symptoms after a prior diagnosis of viral conjunctivitis. VA is 20/100 and fluorescein examination is notable. Which ophthalmic treatment is most appropriate?

• A. Tobramycin
• B. Ciprofloxacin
• C. Erythromycin
• D. Gentamicin

Answer: (A)

Pain, photophobia, and a corneal epithelial defect on fluorescein staining point to keratitis rather than simple conjunctivitis. The priority is to start topical antibiotics that cover likely bacterial pathogens capable of rapidly threatening the cornea, especially Pseudomonas. Tobramycin, an ophthalmic aminoglycoside, has strong activity against gram-negative bacteria including Pseudomonas and penetrates the cornea well, making it a preferred first-line option for suspected bacterial keratitis. Erythromycin isn’t reliable for this indication due to limited Gram-negative coverage and poor corneal penetration. Gentamicin has similar coverage but tobramycin is generally favored for ocular infections because of its efficacy against Pseudomonas in the cornea. Ciprofloxacin could be an alternative, but given the typical teaching emphasis here, tobramycin best fits the scenario of treating corneal involvement with potential Pseudomonal infection.