Close Focus and Reading
The young human eye (before presbyopia) can focus at one distance at a time - either far or near. Move slider to simulate.
Santa Monica Pier photo (c) Alan Levenson
See Far and Near, Without Glasses or Contacts.
In our modern, multi-tasking world, people are often challenged by viewing different items at different distances. We want perfect vision for all ranges -- cell phones, computer monitors, tablets, newspapers, price tags, dashboard instruments, road signs, food on a dinner plate, sheet music, the channel guide on TV, night driving on the freeway, and in a movie theater.
Do you sometimes feel like this?
If you're over 45,you have probably noticed that your reading clarity is not what it used to be. If you are now having difficulty seeing your cell phone, computer monitor, restaurant menu or newspaper, you’re not alone. Everyone will eventually experience presbyopia, or the ability to focus on objects up close.
Reading glasses and bifocals are the most common answer, but there are other treatment options that allow Dr. David Wallace and LA Sight to restore vision at all distances without glasses or contacts.
The human lens is made of protein; it's transparent and very flexible when we're young. The lens is surrounded by a circular muscle and when this muscle contracts, the lens changes its shape, enabling focus adjustment on objects up close, much like an auto-focus camera.
As we age, extra layers of protein that naturally develop cause the lens to become more rigid. As a result, we lose our ability to flex the lens when we shift our focus. This condition is called presbyopia, and is what causes the need for reading glasses or bifocals.
Since it is a condition of the lens and a natural part of the aging process, it affects everyone, usually at about 45 years of age. Normal glasses and contact wearers, people with perfect vision, and even people who received laser vision correction will all develop presbyopia at some point in their lifetime.
Accommodation: In a young person, the human lens can change shape to adjust focus
(Note:Flash animations will not display on iOS devices (iPhone, iPad), as Apple currently does not support Flash)
Loss of clarity at close range is a direct consequence of presbyopia. One of the oldest (and still very good!) solutions is to use simple magnifying glasses ("readers") if you don't need any distance prescription. Alternatively, if a distance prescription is worn, then bifocals (a lens with two different focal properties, originally invented by Benjamin Franklin!) will correct for the two different focal ranges, distance (upper section) and reading (lower section).
When reading about any proposed surgical option that tries to correct for loss of reading comfort, it's important to understand that no corneal surgery can reverse or optically correct for loss of accommodation in the human lens. These and other surgical options can at best afford optical compromise solutions -- they are imperfect treatments, but not a cure. Some of them are in our opinion "not quite ready for prime time". We'll still endeavor to describe them in this section.
Options for People who Desire Near and Distance Vision
At present there's a relatively short list of existing and emerging technology attempting to restore reading vision.
- Reading Glasses or Bifocals - These are by far the most time-honored, cost-effective and prevalent solution available in the modern world. With the obvious limitation that glasses are required for reading.
- Multifocal Contact Lenses - Although various types of multifocal soft contact lenses have been around for over 25 years, they have their limitations. Generally, even when fit by an expert, these are not highly successful long-term solutions. Part of the reason is optical (blur at distance when viewing through the reading portion of the lens and vice versa), part is functional (computer monitor viewing creates different visual demands than when looking down to read, etc.) and part is climate-related. In the Los Angeles area, which is hot, dry, dusty and sometimes smoggy, it's difficult for most people of presbyopic age to comfortably tolerate contact lens wear for prolonged periods.
- Raindrop Corneal Lens Implant
- Kamra Corneal Inlay
- Clear Lens Exchange (cataract style surgery with IOL placement)
A popular solution for seeing without readers, monovision takes advantage of the brain's natural tendency to rely on your dominant eye for distance vision, and your non-dominant eye for close up sight.
With monovision correction by LASIK, one eye is corrected for distance, and the other eye is adjusted for near-range vision. While this may seem awkward, many people adapt nicely and enjoy good viewing comfort at near and far distances.
Monovision has been used for years with contact lenses, and can be a great option for anyone looking to reduce their dependence on readers. It is not a perfect solution and it's not for everyone, which is why we suggest trying monovision first with soft contact lenses. Monovision is an acceptable option for many (but not all!) individuals who desire to avoid reading and distance glasses. Like reading glasses and bifocals, it's not a perfect solution to the optical challenges of presbyopia. With monovision, when driving at night, the near-focused eye will see blurry at distance, so driving comfort, depth perception and night viewing comfort can be diminished. Some who enjoy monovision do have a pair of eyeglasses they keep in the console of their car to correct the near eye for distance, which resolves these issues. Monovision is a compromise, and it is not for everybody. If a group of people try monovision correction in soft contact lenses, roughly 40% will like it. About 30% will feel uncomfortable or off-balance. The last 30% will have difficulty making a decision one way or the other. The best way to know if monovision will work for you is to try it in contact lenses. We find that satisfaction with monovision laser treatment is extremely high if people understand the limits of presbyopia and participate in the process of choosing whether or not to have monovision-style treatment.
RainDrop Intra-Corneal Lens and Kamra Intra-Corneal Inlay
is a very tiny lens (2mm diameter) that can be placed within a corneal flap. It's basically a form of monovision, and these inlay lenses are only implanted in one eye, like the Kamra. The Raindrop lens received FDA approval for use in mid 2016, in the US, though it has been available in Japan, the European Union and certain other countries for much longer.
The Kamra Acufocus Corneal Inlay
is a tiny disc that can be implanted within the cornea. It has an opaque periphery and a small clear center. This forces the light rays to enter the eye through a very small effective pupil, almost like looking through a pinhole. Just like a camera lens, stopping down the aperture (f-stop) increases depth of focus. The Kamra is intended for use only in one eye as it does impair night vision and low light sensitivity, which is an obvious consequence of the very small pupil. The Kamra inlay received FDA approval in early 2016 for use in the US.
Clear Lens Exchange (CLE), or clear lens replacement surgery, is a treatment that is identical to cataract surgery; the only difference is that the natural lens removed hasn't begun to develop a cataract.
With CLE, the clear natural lens of the eye is removed, and replaced with one of the available premium intraocular lenses (IOLs) designed to provide clear vision at all distances. As an added bonus, you won't have to worry about developing cataracts!
There are two main lens lens options for CLE surgery: multifocal & accommodating.
Multifocal IOLs - Multifocal IOLs have multiple viewing areas much like bifocal glasses. These lenses are designed for patients to see multiple distances through different parts of the same lens. Current multifocal IOLs including the Tecnis and ReStor can work very nicely, but they are not perfect. Generally this option is reserved for patients in their mid-50s or older.
Pseudo-Accommodating IOLs - The Crystalens attempts to mimic the function of our natural young lens with a special design that intends the lens to move when your eye's focusing muscles flex (accommodate).
Comprehensive Reading Vision Consultation
Our goal at LA Sight is to provide patients with the most accurate and unbiased information possible, so that you may make the best decision for your vision. We understand that to choose to undergo any surgical procedure requires careful consideration and planning. That's why we offer patients a comprehensive reading vision consultation and screening so that you can feel comfortable and educated about your options.
We've helped thousands of patients reduce their dependence on reading glasses. if you're interested in learning more about your options available to ditch the readers for good, then schedule your free consultation with LA Sight today. We'll be happy to evaluate your vision, and help determine the best course of action for your needs.
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