Most people will experience gradual vision loss as they age. Beginning at 40 years old, the most common vision problem is presbyopia. This defect affects the majority of old people. In detail, presbyopia is caused by the stiffening of the eye’s lens. As a person becomes old, the lens gradually loses its ability to adjust and change shape in order to perceive objects at different distances.
Presbyopia will progress throughout one’s life. Most people realize this condition first because they can not see near things clearly. Presbyopic individuals always have to hold objects such as newspapers and maps further away, only in which way can they see them clearly. This is the most obvious symptom of presbyopia. To some degree, presbyopia can not be avoided or prevented. Even if a person has never suffered from any other vision problems, presbyopia is quite possible.
Regular eye exams and doctor’s visits can detect presbyopia as early as possible and offer early treatment. In this way, the impact on daily lives caused by presbyopia can be minimized. Present now, reading glasses and bifocal lenses are commonly used as treatments for presbyopia. These devices in either rigid gas permeable or soft type can effectively restore one’s normal vision.
Similar to traditional eyeglass lenses, alternating bifocal contact lenses perform vision correction in a similar way. A bifocal contact lens has two different prescriptions, one for near vision and the other for distance vision. A wearer needs to look upward or downward in order to choose the appropriate prescription.
Simultaneous bifocal contact lenses are different from alternating bifocals. A simultaneous bifocal lens also has two different prescriptions but they are blended. The eyes will determine which power is suitable based on the current viewing distance. They are similar to progressive bifocal contact lenses.
Monovision contact lenses treat one eye for distance vision and the other for close vision. In most cases, the dominant eye is corrected to see distance objects.