The Pinhole Effect
The eye is similar to a camera. When you squint to bring something into focus, it is the back of the eye that is affected. In photography terms, this is known as depth of field. Light let into the camera set to a smaller aperture, for instance, f/16, will create a deeper depth of field and bring both the background and foreground into focus.
What Does That Mean?
Light is let in through a small opening, much like letting light in through a pinhole. The same thing occurs in the eye. By squinting, light enters the eye in a very small, concentrated way, blocking out all other surrounding light. The light then bounces off the retina, located at the back of the eye, refocuses the lens, and thus, allows you to bring more into focus.
Be wary of scams that advertise better vision with pinhole glasses. Pinhole glasses are black with a dozen or more pinholes where the lenses should be. The idea is to wear the glasses for short periods of time with the promise of improving your vision. There is no scientific evidence to support this claim, and many scam artists prey upon those with poor vision, charging high prices for a pair of glasses that offer nothing beyond vacant promises.
There is, however, a new technology that can help you keep track of your vision overtime at home. The EyeQue Personal Vision Tracker and the second generation, EyeQue VisionCheck, will measure your refraction (the measurements that go into making your eyeglasses) and the EyeQue Insight will screen your visual acuity, color blindness, and contrast sensitivity – all from home.
When Squinting Is a Bad thing
Squinting frequently can indicate the need for a more permanent corrective measure, like glasses or contact lenses. If you find yourself squinting all the time, contact your eye doctor for an eye exam. Otherwise, try moving closer or further away from the object you’re trying to bring into focus.
Excessively blurry vision could also be a sign that the eye is damaged in some way. Again, you should consult your eye doctor to make sure your reason for squinting isn’t due to something more severe than normal vision deterioration as a result of age.