Differential Diagnosis for Central Corneal White Opaque Lesion

• Single Most Likely Diagnosis
  • Acanthamoeba Keratitis: This is the most likely diagnosis given the patient's history of showering while wearing contact lenses, which increases the risk of exposure to Acanthamoeba. The presence of a central corneal white opaque lesion with a halo and endothelial keratic precipitates, not responding to typical antibacterial treatments (fluoroquinolones, polymyxin B, and bacitracin), further supports this diagnosis. Acanthamoeba keratitis is known for its resistance to conventional antibiotic therapy and its characteristic ring-shaped infiltrate.
• Other Likely Diagnoses
  • Fungal Keratitis: Fungal infections can also present with similar symptoms, especially in contact lens wearers. The fact that the lesion is not responding to antibacterial treatment could suggest a fungal etiology. However, the history of showering in lenses might lean more towards Acanthamoeba.
  • Bacterial Keratitis (atypical or resistant organisms): Although the patient is not overwearing lenses and the lesion is not responding to standard antibacterial therapy, an atypical or resistant bacterial infection could still be considered, especially if the patient has been exposed to contaminated water.
• Do Not Miss Diagnoses
  • Herpes Simplex Keratitis: This condition can present with a variety of corneal lesions, including dendritic ulcers, which might not always be typical. Given the potential for serious complications, including vision loss, missing this diagnosis could be detrimental.
  • Syphilitic Keratitis: Although less common, syphilitic keratitis can present with interstitial keratitis and should be considered in the differential diagnosis of any corneal infiltrate, especially if other systemic symptoms are present.
• Rare Diagnoses
  • Leishmaniasis: This parasitic infection can rarely cause ocular manifestations, including keratitis, especially in endemic areas. It would be an unusual cause of the described symptoms but should be considered if the patient has traveled to or lives in an area where Leishmaniasis is common.
  • Microsporidial Keratitis: Another rare cause of keratitis, especially in immunocompromised patients or those exposed to contaminated water. It might present with similar symptoms and should be considered if other diagnoses are ruled out.