Ophthalmic medications

• Solutions: Safer if ocular integrity is questionable. Short contact time.
• Ointments: Cause severe uveitis if they enter the globe. Longer contact time.

Pharmacology

• When possible choose antibiotic based on culture and sensitivity.
• While waiting on C and S try to base drug choice on cytology.
• Topical formulations can be made from IV preparations.
• Sometimes a stronger concentration may be desired than that available commercially, and fortified concentrations can be made.
• Oral antibiotics are indicated with perforation or impending perforation, eyelid disease, nasolacrimal disease, and vitreal infections (rare)

Antibiotics

• Triple antibiotic contains neomycin, polymixin B and bacitracin (or gramicidin). This is used for routine prophylaxis.

  • Neomycin
    • Aminoglycoside
    • Bactericidal for many gram positive and gram negative organisms
  • Bacitracin or Gramicidin
    • Primarily is bactericidal against gram positive organisms
    • Resistance is rare
  • Polymixin B
    • Bactericidal against gram negative organisms
    • Development of resistance is unlikely

• Aminoglycosides

  • Basic spectrum is gram negative
  • Gentamicin, tobramycin

• Chloramphenicol

  • Basic spectrum is gram positives, some gram negatives, mycoplasma, Rickettsial NOT Pseudomonas
  • Penetrates the intact epithelium better than most antibiotics
  • Beware of public health significance (can result in fatal aplastic anemia in people)

• Cephalosporins

  • Gram positive and gram negative spectrum
  • Gram positive spectrum decreases and the gram negative spectrum increases with increasing generations
  • Low efficacy against Pseudomonas

• Ciprofloxacin (and other fluoroquinolones)

  • Broad gram-negative and gram-positive spectrum, Mycoplasma and Chlamydophila
  • Should be reserved for severe infection, should not be used for prophylaxis
  • Penetrates the intact epithelium better than most antibiotics

• Oxytetracycline

  • Clinical relevant spectrum of activity is narrow: rickettsial organisms, Mycoplasma spp., Chlamydophila spp., and Moraxella spp.
  • Inhibits matrix metalloproteinases (MMPs)
  • Anti-poptotic and anti-inflammatory effects
  • May hasten healing of indolent ulcers

Anticollagenase agent

• Serum
  • Contains macroglobulins and other substances that decrease matrix metalloproteinase activity and increase epithelial healing.
  • Let blood clot, centrifuge, draw off the serum. Keep it sterile and refrigerated. Good for 1-2 weeks. If it gets cloudy or contaminated discard. Bacteria proliferate in serum and infected serum would not help the ulcer heal!!!

Cross-linked hyaluronan (Remend)

• May accelerate resolution of corneal ulcers
• May encourage a more normal epithelial architecture

Parasympatholytic drugs

• Atropine
  • 1% ophthalmic solution and 1% ophthalmic ointment (solution is bitter tasting)
  • Onset of action 1-2 hours in normal eyes
  • Duration of action several days to several weeks in normal eyes
  • When uveitis is present, it will take longer for the drug to act and it will have shorter duration. Often use QID when starting therapy.
  • Action: Paralyzes ciliary muscle and iris sphincter muscle; therefore, decreases pain and dilates pupil, respectively.
  • Avoid when glaucoma is present.
  • Normal tear production is controlled primarily by the parasympathetic nervous system; therefore, one can get decreased tear production with use of atropine.
• Tropicamide
  • 1% ophthalmic solution
  • Routinely used for ophthalmic examinations
  • Onset 10-20 minutes in normal eyes
  • Duration 6-12 hours in normal eyes
  • May not work in eyes with uveitis because it is relatively weak compared to atropine Can be used more safely than atropine when glaucoma is suspected