Understanding Reading Difficulties After Age 40

Presbyopia is the gradual loss of your eye’s ability to focus on near objects once you reach your early 40s. Most people first become aware of the symptoms when needing to hold reading material further away to make it clear. The exact mechanism is still being investigated, but it widely accepted to be related to the crystalline lens within the eye thickening, hardening, and therefore becoming less flexible. This flexibility is necessary for the eye to focus on near objects. The ciliary body, the muscle responsible for flexing the lens, is likely also undergoing age related changes at the same time. It is an annoying, but natural, part of aging.

Despite what you may read on many internet sales pages, no exercise program, eye drops, or vitamins can prevent or reverse presbyopia. However, current methods to relieve the symptoms of presbyopia are numerous and new methods are being researched.

Current Methods

The oldest, and still most widely used, method for relieving the symptoms of presbyopia are multifocal glasses. With multifocal glasses, your distance prescription is placed in the upper half and your reading prescription in the lower half. These glasses can either be made with the tradition line (bifocal) or without a line (progressive).  Progressives have the added benefit of also providing mid-range vision, such as computer distance, which a bifocal cannot.

Contact lenses can also correct the symptoms of presbyopia. With contacts, there are two ways to accomplish this, either through monovision or multifocal contacts.  With monovision, one eye is corrected for distance vision while the other eye is corrected near vision. Although sounding difficult to get used to, most patients are unaware that they are only seeing clearly though one eye at a time. The most commonly reported adverse symptom is nighttime driving glare associated with the reading-corrected eye.

With multifocal contacts, in contrast, both eyes continue working together at all ranges. They accomplish this through simultaneously combining your distance and reading prescriptions.  However, as with most things in life, trying to do two things at once rarely does both perfectly.  There is typically some small sacrifice in distance or reading clarity since you are looking through some distance power when reading and some reading power when looking far away. However, for many patients who have difficulty with monovision this is an acceptable tradeoff in order to be free from glasses.

Lasik can correct the symptoms of presbyopia using monovision, as we saw with contacts. One eye, typically your “dominant” eye (the eye you would sight a telescope with) is corrected for far vision and your non- dominant eye is corrected for near vision. You will typically be given a pair of contacts for a trial period to insure you adapt well to monovision and that the reading eye is set for an appropriate distance before the procedure is performed.

Future methods

Lasik software developers are working on a way to provide both distance and reading vision simultaneously through a laser. In a method similar to multifocal contacts, the laser would shape the central cornea (the front clear surface of the eye) to provide reading vision and shape the peripheral cornea to provide distance vision.

Corneal inlays are physical rings inserted into the cornea. Similar to multifocal Lasik software, this ring modifies the central curvature of the cornea to provide reading clarity. The inlay can be removed easily if the need arises. Although this method is currently being performed across the country, most of the procedures are being done as part of clinical studies.

Turning 40 means having to choose among methods of vision correction you have never been presented with before. The good news is you have many options and your optometrist will work with you to choose the one that best meets your lifestyle in a way that keeps you from missing a step in your daily activities.

~ David McCleary, OD
California Optometric Association

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