Biomedical subjects
Publications and source records attributed to L M DeDonato.
This study examined the short-term hydration changes of hydrogel contact lenses with wear. Changes in the water content of 12 new Bausch & Lomb hydrogel contact lenses were calculated from the change in weight of the lenses after they were worn. The mean of the calculated water contents after wear was 27.9%. This compares with the 38.6% water content of new, fully hydrated lenses.
The amount of gas moving through a contact lens depends upon its permeability to the gas and its thickness. The lens thickness used to calculate transmissibility is often the center thickness, which is rarely the average lens thickness. A technique is presented which shows how lens mass can be used to determine the average lens thickness. This average thickness can be used to calculate the oxygen transmissibility of a contact lens of known oxygen permeability.
Limbal injection, peripheral corneal edema, and adjacent leukocyte infiltration may all be involved in the neovascularization of corneal tissue. Hydrogel lenses should be made with a minimum average thickness an maximum water content to increase oxygen transmission to the cornea. Lenses should not compress the limbal area in order to decrease the risk of limbal injection and, therefore, possible leukocyte invasion. Following these guidelines will decrease the risk of corneal vascularization in the hydrogel contact lens wearer. Keeping these principles in mind will also help the practitioner evaluate corneal health in all patients.