Transmission of light across the adult and neonatal eyelid in vivo.

Light transmission characteristics of the human adult and neonatal eyelid were measured in vivo. Light was delivered via a grating monochromator through a fibre-optic mounted onto a contact lens placed under the eyelid, and detected using a photodiode on its external skin surface. Data from 5 adult and 9 preterm neonatal subjects indicate that the eyelid acts as a predominantly red-pass filter, with mean transmissions at 700 nm of 14.5% in the adult and 21.4% in the neonate, declining to less than or equal to 3% in both groups below 580 nm. The relevance of this data to clinical electrophysiology and to estimates of retinal irradiance is discussed.