Presbyopia or eyestrain is the decrease in sharpness of near vision that typically appears from age 40-50. It manifests itself as a difficulty in focusing up close, which forces us to move the book away in order to read it.
The crystalline lens is the natural lens of the eye, and has the power to focus images on the retina by changing its curvature. Over the years, the crystalline lens loses elasticity and therefore its ability to accommodate or focus, making eyesight appear tired.
Tired eyesight appears progressively, initially the patient will make a visual over-exertion to focus the images or move the objects away to see them better. As you progress, it becomes essential to wear glasses for close-up work in order to see properly. These can be used for near vision only in some patients, or they can be progressive all-distance glasses in patients who also need correction for distance vision if they are nearsighted, farsighted or astigmatic.
Presbyopia treatment is usually done with glasses as we have mentioned, generally with progressive lenses, which allow us to focus at all distances using different parts of the glass. Most patients today adapt to progressive lenses, but in case of difficulty bifocals can be used. Some patients may also find it useful to wear contact lenses in what we call “mono-vision”. This means that by using a suitable contact lens, we leave one of the eyes slightly myopic so that it can focus up close. The other eye (the dominant or better vision) is graduated for distant vision.
Presbyopia surgery in those patients who so desire, involves replacing the presbyopic lens with an interocular lens that allows us to focus at various distances. Lens surgery is primarily a cataract surgery. It is performed under anesthesia in drops, through a series of microincisions that allow us to “suck” the lens and replace it with the chosen lens. Visual recovery is usually complete after 24 hours, although some cases may require 2-3 days for complete recovery. In some cases, surgery can be performed on both eyes on the same day. This surgery also corrects the myopia, hyperopia or astigmatism that the patient may have. Furthermore, as it is a surgery that acts on the lens, the operated patient will no longer develop cataracts and the result will be stable over time.
The success of the intervention will be determined by the appropriate selection of the lens implanted in each case. The choice of lens will be determined by several factors: the characteristics of the eye, the patient’s preferences, age or profession.
There are basically two ways of correcting eyestrain through the use of intra-ocular lenses:
Single vision lenses are used. The dominant eye is left graduated for distance and the other eye is slightly myopic, with this a very satisfactory result is achieved in selected cases.
Advances in design optics have allowed great advances since their first designs. Today, we basically talk about the Trifocal Intraocular Lens. The design of this lens allows adequate distance, near and intermediate vision (computer). With proper patient selection, the degree of satisfaction with this technique is very high, with total independence of glasses.
It is essential to emphasize that the previous study of each patient is very important before being able to recommend a treatment.