Presbyopia is a condition that occurs during the aging process. As a person ages, the muscle surrounding the cornea weakens, so the eyes are not able to focus as clearly. For this reason, a prescription contact lens in the form of bifocals is provided by a physician. These bifocal contact lenses are placed over the eye, and they help a patient's vision and allow them to conduct daily activities.
Cause
There is no definitive age for signs of presbyopia. The condition can show up as young as 30. For most people, the need for bifocal contact lenses is during elderly years as a normal part of aging. Diabetes causes high blood pressure, so it can lead to blurry vision and the need for prescription contact lenses.
Types
Three types of bifocal contact lenses exist. For most people who require bifocals, a gas-permeable contact lens is used. A gas-permeable contact lens is a rigid contact that allows oxygen to enter the cornea. The lens allows air to permeate to the tissue, allowing oxygen molecules to exchange gas. Soft contact lenses are also available. These lenses incorporate water into the lens structure. However, these lenses are not as efficient for bifocal users. The third type is a PMMA lens, but these contacts are used less often, since they do not allow oxygen to enter the cornea.
Use
A bifocal contact lens is placed on the eye. The contact "sticks" to the eye using surface tension. This tension uses friction that is on the surface of the contact lens. This action is similar to the surface tension of a water droplet to a glass. The bifocal lens wearer may need several days to adjust to the lenses.
Structure
The bifocal contact lens is made up of an upper and lower lens. Instead of one lens for conditions such as nearsightedness or farsightedness, a bifocal has the capabilities of both. When the patient reads, he uses the part of the lens that helps him focus on objects that are near. When driving, the patient uses the part of the lens that allows him to focus on distant objects.
Care
When using contact lenses, the patient should take care of the prescription. Always wash hands before touching the contact lens. Bacteria from the skin or in the environment can infect the eye, so patients need to disinfect contact lenses before placing them on the eye. The container that holds the lenses should be washed with warm soap and water. If contact lenses are for daily use only, do not reuse them or try to disinfect them for reuse.
