The cornea has no blood vessels. The majority of the oxygen needed to open the eyes comes from the outside air. After wearing glasses, the lenses will block some of the oxygen from entering the eyes. If the oxygen permeability of the lenses is poor and they are worn for a long time or excessively, it is possible to cause repeated hypoxia in the cornea. The most serious consequence is that blood vessels grow from the outer edge of the cornea to the center, forming corneal neovascularization.
At the beginning, there was no obvious symptom. But when vision loss, red eyes or sensitivity to light occurred, the situation became more serious. However, as long as the wearing is stopped in time and professional treatment is received, the condition can generally be controlled and will not continue to deteriorate.
Generally speaking, the oxygen permeability of siloxane hydrogel lenses is better than that of ordinary hydrogel lenses. However, the material itself is not the only criterion for evaluation. The thickness, power and design of the lenses will all affect the oxygen permeability effect. The choice of lenses should be based on the wearing time, the condition of the eye surface and the results of the optometry, and it cannot be determined solely by the promotional parameters.
Some people think that lenses with a higher water content will feel more moisturizing when worn. However, lenses with a high water content may be a bit softer at the beginning, but their comfort level after long-term wear may not necessarily improve significantly.
The base curve determines the contact between the lens and the eyeball. If the lens is too tight, it will hinder the exchange of tears, while if it is too loose, it is prone to slipping off the eyelid, causing discomfort such as friction and foreign body sensation. Therefore, the base curve cannot be determined solely based on feeling. It is best to have a corneal curvature measurement done at a professional ophthalmic hospital before making a choice.
The diameter of the cosmetic contact lenses should not be too large either. If it is too large, it may cover too much of the eye surface tissue, leading to issues such as hypoxia, friction, and discomfort. The appropriate diameter of the cosmetic contact lenses should be determined based on the size of the cornea and the overall wearing sensation.
