The permeability of human eyelid skin to topically applied lidocaine

© 2019 Published by Elsevier B.V.This work investigated the permeability of lidocaine across human eyelid skin and compared this with published data for abdominal skin to understand the characteristics of this type of skin and whether topical anaesthesia for eyelid surgery may be feasible. Eyelid skin is thought to have a relatively high permeability to drugs, however how this compares to other body sites has not been previously quantified. Lidocaine solutions at pH 7.0 and 5.5 were applied to human eyelid skin mounted in Franz diffusion cells. Anatomical features of eyelid skin that may be linked to its increased permeability, superficial corneocyte area and stratum corneum (SC) thickness were measured using light microscopy. Steady-state fluxes of lidocaine at pH 7.0 and pH 5.5 were 283.9 and 41.0 μg/cm2/hr, 2.4 and 3.2 times greater respectively than literature values for abdominal skin. Superficial eyelid corneocyte area (800.5 μm2) was 35% smaller and the eyelid SC thickness (14.9 μm) was 31% thinner than reported abdominal skin values. These suggest that a shorter diffusional pathlength across the eyelid SC contributes to increased lidocaine permeability. The relatively high permeability of eyelid skin to lidocaine indicates considerable potential for achieving strong topical anaesthetic effects at this site.Peer reviewe

Impact of Eye Cosmetics on the Eye, Adnexa, and Ocular Surface

Despite the fact that cosmetic products undergo rigorous testing to ensure they are safe for human use, some users report mild discomfort following their application. The cutaneous changes, such as allergic dermatitis, are well reported, but the ocular changes associated with eye cosmetic use are less so. Some pigmented cosmetic products may accumulate within the lacrimal system and conjunctivae over many years of use, but immediate reports of eye discomfort after application are most common. Changes to the tear film and its stability may occur shortly after application, and contact lens wearers can also be affected by lens spoliation from cosmetic products. Additionally, creams used in the prevention of skin aging are often applied around the eyes, and retinoids present in these formulations can have negative effects on meibomian gland function and may be a contributing factor to dry eye disease. The aim of this review is to summarize current knowledge regarding the impact of cosmetic products on the eye, ocular surface, and tear film