ABSTRACT
Purpose: Ophthalmic diagnostic devices require patient and operator to be physically close during the exam. Goal of this study is to develop and release protective measures to increase patient and operator protection during COVID-19. Methods: We applied recommendations by the World Health Organization (WHO), the Center of Disease Control (CDC) and the Environmental Protection Agency (EPA) to the situation in the ophthalmic exam room, and developed, released, distributed, and communicated the resulting protective measures. We report the number of website visits, document downloads, and parts distributed from March 2020 through February 2021. Results: Detailed instructions on remote control of ophthalmic devices using remote desktop software or extension on monitors were published, viewed 4,450 and downloaded 1,014 times. Custom breath shields separating operator and patient were developed and a total of 82,827 have been shipped, free of charge or at-cost. Third party order information for single-use plastic bags and dental barrier film that fit ophthalmic devices and can cover high touch surfaces has been published on a dedicated web page. All cleaning instructions have been published in one place (viewed 25,819 times, downloaded 11,781 times). Highly accelerated lifetime tests were performed to confirm that frequent cleaning and disinfection of the HFA bowl with a spray of atomized isopropyl alcohol will not damage or alter the performance of the bowl. Updated disinfection instructions have been published and downloaded 8,318 times. An additional highly accelerated lifetime test has shown that the bowl inside the HFA can be disinfected using UV-C radiation without damaging the functionality of the perimeter. Conclusions: In response to the COVID-19 pandemic, we have provided improved cleaning instructions for the HFA family of bowl perimeters, have developed and distributed over 80,000 breath shields, have identified protective coverings for high-touch areas, and have developed and communicated different ways to operate existing devices remotely. While we have not been able to quantify the effectiveness of the individual measures, it is our assumption that implementing these measures which are based on recommendations by the WHO, the CDC, and the EPA, have increased patient and operator protection.
ABSTRACT
Purpose : Automated bowl perimeters present unique challenges for disinfection between patients during the SARS-CoV-2 (COVID-19) pandemic. International public health guidelines recommend the use of 70% isopropyl alcohol (IPA) or Ultraviolet-C light (UV-C) for disinfection. In this study we evaluated the effect of repeated exposure on the visual field stimulus in Humphrey Field Analyzers. Methods : We subjected perimeter bowls (HFA3 Model 860, ZEISS, Dublin, CA and HFA IIi, ZEISS, Dublin, CA) to highly accelerated life tests (HALT) for exposure to IPA or UV-C. For IPA, the device was sanitized with an IPA atomizing spray 15 times, followed by an 84hr IPA deep soak of components integral to the stimulus. For UV-C (Figure 1), materials of concern were irradiated with a 254nm light for a cumulative lifetime exposure of 22.8 kJ/cm . This represents an excess of 75,000 disinfection cycles at above the 1-Log Reduction (D ) dose for COVID-19. The effect on the visual field stimulus (combination of projected stimulus and background illumination) was evaluated either by auto verifying that the correct luminance values were recorded at calibrated positions on the instrument or by manually measuring the chromaticity and luminance of the bowl. Results : Automatic verification tests on an HFA3 after exposure, showed that the instrument was within tolerance with a reading error spread less than 1dB for an attenuation range of 0-34dB (Table 1). UV-C exposure to the HFA II-i bowl itself resulted in a shift of less than 0.002 in chromaticity and 18fL in luminance. Other plastics (chin rest, cover, and baffle) were visibly affected by UV-C and exhibited a shift in chromaticity (> 0.02) and luminance (> 114fL) but this did not affect the visual field stimulus. Conclusions : There was no effect on the visual field stimulus in an HFA3 or an HFA II-i after repeated exposure to 70% IPA or UV-C at 254nm for the lifetime of the instrument. There was visible solarization on some plastics, however these did not affect the test performance;they were either outside the bowl or were compensated by the stimulus intensity.