An eye doctor has advised “dolly-eye” contact lens (娃娃鏡片) wearers to limit their use to just six hours and to remove them as soon as discomfort occurs.
The popular cosmetic contact lens makes the wearer’s irises appear larger, but are made of silicone hydrogel, which means the lens does not absorb oxygen well.
A survey carried out in August and September last year found the lenses are favored by 40 percent of contact lens users, mostly women aged between 25 and 45.
The poll also found that 70 percent of those surveyed said they experienced discomfort while wearing lenses, yet nearly 50 percent said they wear them for more than nine hours a day.
Lu Da-wen (呂大文), director of Tri-Service General Hospital’s Department of Ophthalmology, warned that wearing contact lenses for long periods would result in eye dryness, burning and redness due to a lack of oxygen.
Colored contact lenses, which are made by adding pigments to the lens, have an even lower oxygen permeability.
Lu said contact lenses are made of either hydrogels or silicone hydrogels. Most of the lenses on the market are of the hydrogel variety, with their oxygen breathing levels limited to between 20 and 40Dk/t (the industry standard measurement for diffusion and solubility over thickness), whereas those made of silicone hydrogels have oxygen transmissibility of more than 80Dk/t.
Because hydrogel contact lenses are softer than silicone-hydrogel lenses, consumers might think they are more comfortable to wear, Lu said, but their oxygen limitation can also damage the cornea, which can lead to blurred vision.
Serious corneal oxygen deficiency can cause corneal swelling or even corneal erosion, he said.
Lu urged contact lens users to have an understanding of contact lenses before purchasing them.
He added that wearers should to limit their daily use to eight hours (or to six hours for cosmetic contact lens), to remove them as soon as discomfort occurs and visit an ophthalmologist.