Reliability of tonosafe disposable tonometer prisms: clinical implications from the Veterans Affairs Boston Healthcare System Quality Assurance Study

Abstract

Purpose Given the Veterans Affairs Boston Healthcare System's recent introduction of single-use Tonosafe disposable tonometer prisms as an alternative to Goldmann applanation tonometers (GATs), this study had two aims: to conduct a large-scale quality assurance trial to assess the reliability of intraocular pressure (IOP) measurements of the Tonosafe disposable tonometer compared with GAT, particularly at extremes of pressure; to evaluate the suitability of Tonosafe disposable tonometer prisms as an acceptable substitute for GATs and for clinic-wide implementation in an academic tertiary referral setting. Methods Ophthalmology resident physicians measured the IOPs of patients in general and specialty eye clinics with the Tonosafe disposable tonometer and GAT. Tonosafe test-retest reliability data were also collected. A retrospective review of patient charts and data analysis were performed to determine the reliability of measurements. Results The IOPs of 652 eyes (326 patients) were measured with both GAT and Tonosafe, with a range of 3-34 mm Hg. Linear regression analysis showed R ¼ 0.93, slope ¼ 0.91, both of which supported the proposed hypothesis, and the y-intercept ¼ À1.05 was significantly different from the hypothesized value. The Tonosafe test-retest repeatability (40 eyes of 40 patients), r ¼ 0.977, was very high, which was further supported by linear regression slope ¼ 0.993, y-intercept ¼ 0.118, and a Tonosafe repeatability coefficient of 2.06, similar to GAT repeatability. Conclusions The IOP measurements by Tonosafe disposable prisms correlated closely with Goldmann measurements, with similar repeated measurement variability to GAT. This suggests that the Tonosafe is an acceptable substitute for GAT to measure IOP in ophthalmology clinic settings.

Guidelines and recommendations for tonometry use during the COVID-19 era

“…[ 36 37 ] Furthermore, other studies supported that Tonosafe ® prism is highly correlated to nondisposable GAT with comparable retest repeatability, suggesting that Tonosafe is an acceptable substitute for GAT. [ 38 39 ] The disposable tip may underestimate IOP slightly (compared with conventional Goldmann) for IOPs above 21 mmHg. [ 36 ]…”

“…The increased cost of nondisposable prisms was derived from the added cost of cleaning solutions and labor involved for disinfection. [ 39 ] In contrast to most departments, the cleaning solution is routinely provided for disinfecting contact lenses and, as such, does not represent any additional cost.…”

“…The estimation of the cost of handheld Tonopen XL cover is $0.42 per one tip cover and around $39,9370 per year after accounting for all associated costs. [ 39 ] I-care tips are more expensive: The cost for 100 disposable for each iCare system (excluding VAT) are; £70 (~$90) for Icare TA01i and ic100, and £50 ($65) for Icare PRO. [ 46 ]…”

Disposable versus non-disposable tonometer prisms: a UK national survey

“…However, there have been reports of outbreaks of epidemic viral ocular infections in ophthalmic clinics worldwide. 3–5 Epidemiological and clinical studies of epidemic keratoconjunctivitis in eye clinics have identified possible contamination with tonometer tips, eye drop bottles and contact with infected healthcare workers as vehicles of transmission (particularly of adenoviral serotypes). 6 7…”

“…The notion of ‘perceived safety’ and evidence showing comparable accuracy and cost between both prism heads have led to a gradual but definite shift to the use of disposable prisms worldwide. 3 4 8 9 The primary aim of this survey was to compare the use of disposable versus non-disposable prisms and to determine the cost–benefits of each in current UK practice.…”