On behalf of all co-authors, we are most thankful for the comments by Grzybowski and co-authors to our article on low endophthalmitis rates after intravitreal anti-vascular endothelial growth factor injections in an operation room.1 They brought up several additional and relevant aspects.
Most importantly, they pointed out that all current studies on endophthalmitis rates after intravitreal injections are difficult to compare, because there are many variables that can impact this rate. It reaches from preinjection preparation, to the use of sterile gloves or the cover of the patients' mouth and nose. One further aspect is the degree of contamination of the air with colony forming units/bacteria depending on whether no air filtration, air filtration with or without laminar airflow is used. Most studies and meta-analysis do not go into these details, but these details appear relevant, especially when we are aiming to compare relatively rare event rates.
Grzybowski and co-workers outlined that the magnitude of injections performed worldwide—continuously increasing—lead to relevant numbers of patients with postinjection endophthalmitis. In addition, most patients require continuous intravitreal anti-vascular endothelial growth factor treatment. Now with more than 10 years of anti-vascular endothelial growth factor drug availability, some patients have reached up to 100 intravitreal injections per eye not even considering that in an increasing number of patients, both eyes are affected. A patient's personal 10-year endophthalmitis risk with both eyes requiring treatment can reach—according to Grzybowski—in a US population–based estimate up to 10%. Would you accept such a risk of severe vision loss?
All over the world reimbursement for intravitreal injections has dropped or is dropping to low rates. It is obvious that intravitreal injections cannot be conducted economically at a reimbursement rate of 120 USD in a setting described in our study. Setting up a conventional Swiss Class I operation room with lamininar airflow costs at least one Mio USD, in addition requiring extensive maintenance cost (e.g., regular HEPA filter changes). The estimates for an operation room minute show a wide spread and depend on numerous factors but usually range from 15 to 20 USD per minute.2
As doctors, our patients' safety should always come first. Our study can clearly not prove that the reduced colony forming units in a laminar airflow setting are the only reason for the low endophthalmitis rate. However it seems likely that the laminar airflow is one important piece in the puzzle. Of course performing injections in the office or in a “designated” room allows shorter procedure times, smother patient flow, and comes at lower procedure cost. Ophthalmic cost of an endophtalmitis—mostly treated as outpatients—are calculated for the United States at approximately 3,000 USD; however, overall costs are much higher.3 The personal impact of loosing an eye is far from any monetary valuation. Currently, less expensive mobile laminar airflow systems become available, but they need to proof a low rate of endophthalmitis in prospective, controlled clinical studies.
We agree with Grzybowski and co-authors that there is no easy answer. However, based on our safety profile, we feel reluctant to change to an office-based setting for our intravitreal injections. Together, we need to make clear to insurers and policymakers that higher standards of safety are associated with higher cost for the injection procedure.