Spectacle Blur may be the culprit...
“Why can’t I see well with my glasses after taking out my contact lenses?”
People who wear contact lenses should be able to switch to their eyeglasses at any time and expect to see just as well. However, some people experience blurred vision when they put on their eyeglasses after removing their contacts. The blurring may be mild to severe and may last from a few minutes to many hours, or even days or weeks; however it is almost never permanent.
If you wear contacts during all your waking hours and never put on glasses, you could have the problem and not be aware of it. But if you need to alternate frequently between eyeglasses and contact lenses for your work, the blur can be an annoying difficulty.
Either way, extended “spectacle blur” is not normal. While a few moments of blurred vision is acceptable, a long period is not, and indicates that your corneas could be getting harmed by the lenses.
What Causes the Blurred Vision?
The primary cause of spectacle blur is that the contact lens slightly “warps” the cornea (the eye’s clear focusing surface, upon which the contact lens floats.) Normally, after a contact lens is removed, the cornea returns quickly to its proper shape.
There are two main contributors to corneal warping: (1) poor-fitting contact lenses, and (2) poor oxygenation of the corneas.
Contact lenses, especially the rigid types of lenses, must fit properly on the cornea. If a lens fits poorly, it can indent the corneal surface and change its shape. But even well-fit lenses can cause some warping by interfering with the amount of oxygen that feeds the cornea. Soft and oxygen-permeable lens materials minimize the problem, but no type can be totally relied on because no lens allows 100% of the oxygen in the air to reach the cornea. In addition, everyone’s corneas are different, and some require more oxygen than can pass through any type of lens.
If the cornea does warp, you are not likely to notice the blurring while wearing your contacts because there is a layer of tears between the lens and your eye. The tear fluid fills in the defect and optically corrects for it. Only when the contacts are removed will you notice a disturbance in vision that your eyeglasses do not correct.
There is no need to fear that wearing contacts might lead to keratoconus (cone-shaped corneas). Keratoconus is hereditary and is not related to the warping caused by contact lenses.
How Do the Different Kinds of Contacts Affect Spectacle Blur?
Any kind of contact lens material can cause spectacle blur, but rigid (PMMA) lenses are the culprit more often than any other type. (Spectacle blur is one reason many hard contact lens wearers have had to stop wearing even well-fit lenses.) However, if you are wearing rigid lenses and they are comfortable and give you good vision, you can continue to do so, but always remember that you need to maintain a schedule of regular eye check-ups.
Soft, semi-soft, gas permeable, and extended-wear contacts all cause less spectacle blur because they are made of combinations of plastics that “breathe”, allowing some oxygen from the air to pass through tiny pores in the lenses.
What Should Be Done Now?
If you are troubled by significant spectacle blur, something is wrong that may need prompt attention. The fit of your contacts will be checked. If refitting is necessary, you may have to stop wearing any contacts at all until your corneas return to their normal shape (at least a week). If the problem is not in the fit, you may need to change to a type of contact lens that allows more oxygen to reach the cornea.
If your vision is so blurred with your present glasses that you can’t use them, it may indicate a serious warping that could take even months to undo. To see clearly while you are waiting, you may need a new pair of glasses. You may even need to have the prescription changed more than once, as the cornea slowly resumes its natural contour. During this period, your corneas will be checked at regular intervals until they become stable.
If there appears to be any chance of permanent corneal damage, you may have to stop wearing contact lenses altogether. While such a drastic step is rarely necessary, the safety of your eyes is always the guiding principle. ~Triad Notes
Dr. Jeffrey Gold is the medical director of Liberty Vision in Hamden, CT. His practice was recently named "The Best Place for LASIK" in the New Haven Advocate Readers' Poll.
Copyright © 2015, Dr. Jeffrey D. Gold. All Rights Reserved.