Breath shields offer variable protection

This experimental study is the first to test the efficacy of slit-lamp breath shields in preventing droplet spray from a simulated sneeze.

Study design

The authors used a spray gun to spray a mist of colored dye on a cardboard slit lamp model. They tested 6 commercially available breath shields and 1 shield made from a plastic container lid. Each shield was sprayed 3 times. The amount of overspray was compared with the breath shield in place or absent.

Outcomes

Investigators tested 7 shields ranging in size from 116 to 924 cm². They found that the amount of overspray contamination varied greatly, from 0.3% to 54%. Larger shields offered more protection, with the largest shield preventing nearly all overspray. Interestingly, a repurposed plastic lid breath shield (513 cm²) permitted only 2% overspray. Attaching shields to the objective lens arm provided more protection than those hung by the oculars. 

Limitations

The authors suggest that breath shields may help reduce respiratory droplets from a sneeze being directed toward the examiner. However, the authors did not test the additional role of a face mask on the patient to prevent droplet spread.

Clinical significance

These findings suggest there is a meaningful advantage for larger slit lamp shields compared with smaller ones. Although the authors do not directly state this, there would be some potential advantage to getting the largest shield that is available and practical for use. The authors also found that a shield made from a curved container lid that is curved toward the examiner may offer meaningful protection as it directs some of the spray away from the examiner’s face.