• Written By:
    Cornea/External Disease, Glaucoma

    The latest Ophthalmic Technology Assessment explores the most effective method for disinfecting reusable tonometers.

    Study design

    A literature search in the PubMed and the Cochrane Library databases yielded 10 studies suitable for inclusion.

    Outcomes

    The data suggests that dilute bleach eliminates both adenovirus and herpes simplex virus, while 70% isopropyl alcohol can reliably eliminate only herpes. None of the methods tested (ethanol, 70% isopropyl alcohol, dilute bleach or mechanical cleaning) can eliminate prions, so the authors recommend single-use tips or disposable covers when treating patients with suspected Creutzfeldt-Jakob disease.

    Equipment should be inspected regularly because any disinfectant method can eventually damage tonometry prisms. Cracks in the tonometer tip may allow the hollow tip to harbor disinfectants and microbes, which then could leach back out during applanation and increase the risk of corneal injury or infection.

    Limitations

    The number and adequacy of studies on this topic are low. No study to date has tested if HIV and HCV are eliminated effectively by 1:10 dilute bleach. Thus, future well-designed studies may provide evidence that will modify current recommendations for tonometer disinfection.

    Clinical significance

    The common practice of using 70% isopropyl alcohol (e.g., alcohol wipes) or 3% hydrogen peroxide has been associated with adenovirus outbreaks. Based on the most current evidence, 1:10 dilute bleach is a single high-level disinfectant with broad efficacy against common infectious agents encountered in eye care. This is the only type of disinfectant that is recommended by both the manufacturers and the CDC for disinfecting applanation tonometers.

    All disinfection methods—dilute bleach, 70% isopropyl alcohol, 3% hydrogen peroxide, ultraviolet light, and even water soaks—will cause varying degrees of damage to tonometer prisms. Reusable tonometers must be checked for damage before applanation to prevent patient harm.