Have you ever woken up in the middle of the night, glanced at the clock and then found yourself squinting to be able to read the numbers? What is going on? Why does squinting help you to see clearer? A slight increase in visual clarity when squinting is real and it’s due to a principle known as the “pinhole effect.”
What Exactly is the Pinhole Effect?
To understand the pinhole effect, let’s start with how our vision works. Your eye is made up of several components that work together as a visual system. The front of the eye is made of the cornea, iris, pupil, and a natural lens that is contained in the lens capsule. At the back of the eye is the retina, where images are focused and then transmitted to the brain.
As light enters your eye, the cornea begins to focus the light toward the lens of the eye. The lens further focuses the light onto the retinae. Light receptors on your retina turn that light into an image for your brain to see. The muscles in the eye change the shape of the lens to focus light at different distances so that we can see up close and far away seamlessly.
For many people without normal vision, glasses and contact lenses aid in bending the light rays into focus.
If light passes through a tiny hole, or pinhole, the unfocused peripheral rays of light are blocked, leaving the already focused light to reach the retina undisturbed. The focused light rays help bring images and objects into clear focus. This is the pinhole effect.
Why Can I See Clearly When I Squint?
When we squint, we mimic the effect of looking through a tiny pinhole. We are only allowing a small amount of focused light rays into the eye and preventing the unfocused rays from reaching the retina. Try it. Make a tiny hole with your thumb and forefinger and look through it without glasses. You will find that you can see more clearly. This is the pinhole effect in action and this is why you can see more clearly when you squint.
What Else Uses the Pinhole Effect?
If you are a photographer, you probably understand the pinhole effect in different terms like “depth of field.” A photographic lens aperture is used to adjust the amount of light reaching the image sensor. Like a pinhole, the smaller the aperture, the broader the depth of field or amount of the image that is in clear focus.
What Does This Have to do With Cataracts?
If you’ve been considering cataract surgery, you may already know that there are several different options for replacement lenses. During cataract surgery, the clouded natural lens of the eye is removed and replaced with a clear artificial lens known as an intraocular lens or IOL. Some IOLs can correct vision at only one distance, some are designed for those with astigmatism, and some correct vision at more than one distance, but often with unwelcome side effects such as blurry zones and glare or halos around lights.
The Apthera™ intraocular lens (IOL) provides a full range of vision from near to far. The Apthera IOL is the only lens that achieves this goal by using – you guessed it – the pinhole effect, also known as small aperture technology.
What is the Apthera Lens?
The Apthera lens has a FilterRing™ component within the lens. This FilterRing component creates a small aperture, allowing focused light to enter into the eye. Unfocused peripheral light that causes blurry vision is filtered away. This provides a continuous range of vision allowing patients to see from near (reading a cell phone), through intermediate (looking at a computer) to far (seeing a streetlight) without blurry zones.1
The Apthera IOL naturally focuses light entering the eye through its small aperture and seamlessly expands your range of vision—so you can see text, people, and objects—across a full range of focal distances.1
Take a look at this short video to learn more about cataracts and the Apthera lens.
Find a qualified Apthera lens doctor in your area.
1 Data on file, AcuFocus, Inc.