Air Filters in OTs: Not Needed for Cataract Surgeries?

Summary: The use of advanced air filters in operation theatres have not affected infections in cataract surgical procedures in any way.

The studies and research

According to a study published in American Journal of Ophthalmology, the air flow and filter installed in the air conditioning units of operation theatres do have any significant impact on patients undergoing cataract procedures. Data from the study shows that the “expensive laminar air flow (LAF) and high-efficiency particulate air(HEPA) filtration may not be a requirement for removing cataracts in clinic or hospitals with fewer resources.
The largest study, till date, is the analysis of records of 452770 surgeries : phacoemulsification or manual small-incision cataract surgeries (MSICS). Surgeons of 14 hospitals of the Aravind Eye Care System in India performed these surgeries during the year 2023. These surgeries involved use of ”standard antibiotic techniques, pre-op processes, instruments, surgical approach and sterilization”.

Post-op infections

Of the total surgeries, 0.016% of patients i.e. 74 eyes, developed postoperative endophthalmitis (POE).

In the case of air conditioners with and without filters, the statistics are as follows:

PARTICULARS	POE RATE
LAF with HEPA	0.013% (95% CI; 0.008 to 0.021)
Central AC plus HEPA filter	0.016% (95% CI; 0.011 to 0.025)
Central AC without HEPA	0.017% (95% CI; 0.011 to 0.028)
Split AC (unit for each room ) without HEPA	0.019% (95% CI; 0.013 to 0.029)

Research showed no significant benefits from LAF or HEPA filter systems on the rate of POE, with reference to paying or non-paying patients as well as MSICS and phacoemulsification cases.

The Aravind Eya Care System uses cost effective measures like disinfection and reusing sanitation gloves for their staff members but even then the POE is under 0.04%. This point of reference has been posted by the American Academy of Ophthalmology Intelligent Research In Sight (IRIS^R) registry.

The rate of POE with or without LAF and HEPA is comparable in India and US. More research with mRNA shows that infections increase more from the surface and adnexa as against airborne micro-organisms from cross-contamination.

Conclusion

This shows that air filter systems may not impact the POE of cataract patients. According to research, air flow and filtration methods are useful for airborne microbes. In case of cataract surgeries, very small incisions are required and the risk of potential contamination is lower for sterile aqueous and intraocular lenses.

Inputs from various media sources.