Which treatment constitutes the emergency regimen for Acanthamoeba keratitis?

Which treatment constitutes the emergency regimen for Acanthamoeba keratitis?

• A. PHMB 0.02% q1h, Propamidine isethionate 0.1%, Cyclopentolate 1% tid
• B. Prednisolone acetate 1% qid
• C. Fortified tobramycin and cefazolin q1h
• D. Moxifloxacin 0.5% q2h

Answer: (A)

Acanthamoeba keratitis needs immediate, intensive topical anti-amoebic therapy that hits both active organisms and cysts. The emergency approach uses a biguanide to broadly disrupt the amoeba’s membranes and metabolism, typically with polyhexamethylene biguanide (PHMB) 0.02% applied every hour around the clock. To boost cysticidal activity and cover additional stages, a diamidine such as propamidine isethionate 0.1% is added, also dosed frequently at the outset. Cycloplegia with a drop like cyclopentolate 1% a few times daily helps relieve pain from ciliary spasm and reduces photophobia, aiding comfort and recovery. This combination is preferred because it directly targets the pathogen rather than just addressing bacterial flora. Corticosteroids are avoided early because they can worsen infection and delay healing, and fortified antibiotic regimens designed for bacterial keratitis do not efficiently treat Acanthamoeba. The emphasis is aggressive, frequent application of anti-amoebic agents to maximize penetration and eradication, with supportive cycloplegia for symptomatic relief.

Acanthamoeba keratitis needs immediate, intensive topical anti-amoebic therapy that hits both active organisms and cysts. The emergency approach uses a biguanide to broadly disrupt the amoeba’s membranes and metabolism, typically with polyhexamethylene biguanide (PHMB) 0.02% applied every hour around the clock. To boost cysticidal activity and cover additional stages, a diamidine such as propamidine isethionate 0.1% is added, also dosed frequently at the outset. Cycloplegia with a drop like cyclopentolate 1% a few times daily helps relieve pain from ciliary spasm and reduces photophobia, aiding comfort and recovery.

This combination is preferred because it directly targets the pathogen rather than just addressing bacterial flora. Corticosteroids are avoided early because they can worsen infection and delay healing, and fortified antibiotic regimens designed for bacterial keratitis do not efficiently treat Acanthamoeba. The emphasis is aggressive, frequent application of anti-amoebic agents to maximize penetration and eradication, with supportive cycloplegia for symptomatic relief.