The transmission characteristics of phototherapy eyeshields have been measured under conditions that mimic the clinical situation. Peak transmission (less than 10%) was detected at 700 nm for the poorest patch tested and less than 2% for either of the other patches examined. The optics of measurement systems are considered with reference both to this and previous studies of light transmission through eyepatches. The simplicity and effectiveness with which eyepatches can be secured may be as important as their transmission characteristics.