This study estimated the economic and environmental impact of single-use applanation tonometer prisms and gonioscopy lenses at an ophthalmology outpatient service at a large tertiary academic center.
Study design
Investigators calculated the plastic waste generated at Boston Medical Center in kilograms and cost in dollars per year. They compared these values against total spending and waste that would be produced if nondisposable tonometer prisms and gonioscopy lenses were used. Literature was reviewed for reported cases of ocular transmission of viral and prion diseases.
Outcomes
During a 2-year period, an average of 61,115 disposable tonometry prisms and 800 single-use gonioscopy lenses were purchased per year, leading to an estimated 109.6 kg in annual plastic waste generated in the 40-lane outpatient clinic. The average total cost was $70,282 for disposable tonometry prisms and $9,040 for gonioscopy lenses ($1.15/visit and $11.30/visit, respectively). For the first year, cost of outfitting each lane with one reusable tonometry prism and each doctor with one gonioscopy lens was estimated to be $6,000 and $11,352, respectively, with annual replacement costs projected to be $3,000 and $2,270, respectively. Per patient visit, the estimated cost of reusables was $0.05 for prisms and $2.84 for lenses. The annual cost of disinfection materials was estimated to be $5,867. Overall, the use of disposable prisms and lenses accounted for $65,185 in excess costs.
Epidemic keratoconjunctivitis outbreaks in the outpatient ophthalmology setting have been reported, but lapses in hand hygiene and improper disinfection were the likely culprits. The potential for HIV, HCV, HBV and prion transmission has been shown in vitro but there are no reported cases in vivo. Adenovirus, HIV, HCV and HBV are eliminated with proper dilute bleach disinfection. While none of the disinfection methods have proven effective for eliminating prions, Creutzfeldt-Jakob disease has an incidence of less than 1 in 1 million per year, with 99% being spontaneous versus 1% acquired.
Limitations
The cost of staff time required to disinfect reusable lenses was not estimated. The additional cost of technician wages may make disposable equipment more financially favorable than is depicted in this publication, though it is unlikely that this added cost would make reusable instruments the more expensive option.
Clinical significance
Outfitting an outpatient ophthalmology clinic with durable gonioscopy lenses and tonometry prisms is not only a more environmentally friendly option than disposables, but it is a cost-saving measure as well. If reusable equipment is properly disinfected with 1:10 dilute bleach for 5 minutes after each use, patients should not incur additional risk. Cutting the utilization of single-use plastics in medicine can help reduce the burden of plastic waste in marine environments and landfills. While it is a more labor intensive option, it has the opportunity to save practices tens of thousands of dollars annually.