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When to be concerned about a change in your eyesight

If you’ve always had great eyesight and suddenly find yourself blinking or squinting because things seem a little fuzzy, it’s time for a checkup. Many cases of blurry or cloudy vision are caused by nearsightedness, farsightedness or astigmatism – common issues that are typically corrected with glasses or Lasik surgery. However, your changing vision could be an important early symptom of a more serious disease or medical condition.

"Not all cases of blurry vision are caused by problems with the structure of the eye," said Geisinger ophthalmologist David A. Carl, MD. "Environmental factors, lifestyle factors, aging and disease may also affect how well you see."


Almost 25 million Americans aged 40 and over have cataracts. By the time they reach 80, more than half of all people have some form of cataracts.

"A cataract is a clouding of the eye’s lens, which is normally crystal clear," said Dr. Carl. "While it’s more common to develop cataracts as you grow older, age is not the only cause."

Doctors think that environmental factors such as exposure to UV rays, smoking and drinking alcohol may also increase your chances for developing the condition. Some babies are born with cataracts due to genetic defects, developmental issues or exposure to a disease called rubella during pregnancy.


Diabetes is another a common cause of blurred vision. When blood sugar is too high, which is common with diabetes, it also makes the glucose level too high in the fluid that surrounds the lens of your eye. This causes the lens to swell and your vision will become blurry. This sugar imbalance can also affect the proteins that naturally occur in the fluid around the lens, which also contributes to the formation of cataracts.

"Conversely, when blood sugar drops too low in response to medication that increases insulin in the blood, diabetics may experience temporary blurriness," said Dr. Carl.


A stroke or transient ischemic attack (TIA or "mini-stroke") can also cause blurry vision. This happens if the stroke affects the part of your brain involved with vision. In fact, a sudden painless change in blurring of your eyesight may be one of the first signs of this very serious medical condition.

"Be especially vigilant if a vision change is accompanied by other classic stroke symptoms," said Dr. Carl. "This includes weakness or numbness on one side of the body, confusion and difficulty speaking or slurred speech."


Migraines sometimes cause temporary vision changes before, during and after the headache. These changes can range from cloudy vision and blind spots to auras, wavy lines and flashes. It’s not clear why some people experience vision changes with a migraine, but there may be a genetic predisposition for the phenomenon. The majority of people who experience these changes have a family member who suffers from the same disorder.

"Vision changes with a migraine are usually temporary and less about 30 minutes or less," said Dr. Carl.

Preventing and treating blurry vision

These common causes – and many more – can create changes in your vision. The most important first step in preventing and treating them is identifying the cause.

"Any change in vision, especially if it’s the first time it has happened, should be considered an emergency," said Dr. Carl. "Once you’ve identified the cause, you and your doctor can work together to avoid the triggers or treat the underlying issue creating your vision problems."

Geisinger Ophthalmologist David A. Carl, MD, sees patients at Geisinger Medical Group, 675 Baltimore Dr., Wilkes-Barre. To schedule an appointment with Dr. Carl or another Geisinger ophthalmologist, please call 800-275-6104 or visit

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