Dear Editor,

We appreciate the valuable comments brought up by Dr. Couret and colleagues regarding our recent article on “The effect of ambient light conditions on quantitative pupillometry.”

Couret et al. raised an important point regarding differences between pupillometer devices. With brands and models that control for ambient conditions themselves by creating a standardized lighting environment with attachments, it is logical that the surrounding light level does not need additional standardization.

We believe that the takeaway for readers is that whether light is controlled through the device itself or through the environment, more reliable measurements are likely to be acquired through standardization of ambient conditions. A recent systematic review cited that the Neuroptics pupillometer is used in over 295 hospitals in the USA and 23 countries [1]. The results of this study may provide valuable insight into the interpretation of pupil measurements taken with devices like the Neuroptics-200 which do not standardize lighting conditions on their own.