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Happy 40th -- Here are your bifocals!
Visual symptoms are some of the earliest telltale reminders of advancing age. Sometimes blurry reading vision predates the first grey hair! Most of us tend to deny these changes until it's nearly impossible to see closeup objects. What's going on?
The medical term for this change in life is called Presbyopia and it is not hard to understand. The healthy eye has two coordinated focusing systems: distance vision (beyond 20 feet, optical infinity) and near vision (another long word, accommodation). At age 5 human beings enjoy peak accommodation and a remarkable agility for shifting focus between far and near. It steadily declines throughout life. By age 40 most folks who do not ordinarily wear glasses start experiencing blurriness while reading because of this progressive loss of accommodation becomes apparent. Most accommodation disappears by age 65.
Farsighted individuals experience this milestone earlier in life -- presbyopia occurs later for nearsighted myopes.
Optics alert! Since the focusing requirement decreases with target distance presbyopes adapt by holding items farther away. Eventually their arms are no longer long enough! Fabricating a second lens to the distance correction provides added near focusing power. Benjamin Franklin introduced the first bifocal eyeglasses. Depending on the specific prescription there may be a blurry intermediate zone (not near, not far) just beyond your reach. In this situation trifocal spectacles or a blended progressive lens will offer a clear image at near, at intermediate distances, and at far away objects.
If you balk at the idea of wearing bifocal spectacles there are multifocal contact lenses and even refractive surgery to eliminate presbyopia.
Related Topics: Slew of New Lenses Act Like Real Eyes, Healthy Diet May Improve Seniors' Vision
Technorati Tags: presbyopia, bifocals, eyehealth
The medical term for this change in life is called Presbyopia and it is not hard to understand. The healthy eye has two coordinated focusing systems: distance vision (beyond 20 feet, optical infinity) and near vision (another long word, accommodation). At age 5 human beings enjoy peak accommodation and a remarkable agility for shifting focus between far and near. It steadily declines throughout life. By age 40 most folks who do not ordinarily wear glasses start experiencing blurriness while reading because of this progressive loss of accommodation becomes apparent. Most accommodation disappears by age 65.
Farsighted individuals experience this milestone earlier in life -- presbyopia occurs later for nearsighted myopes.
Optics alert! Since the focusing requirement decreases with target distance presbyopes adapt by holding items farther away. Eventually their arms are no longer long enough! Fabricating a second lens to the distance correction provides added near focusing power. Benjamin Franklin introduced the first bifocal eyeglasses. Depending on the specific prescription there may be a blurry intermediate zone (not near, not far) just beyond your reach. In this situation trifocal spectacles or a blended progressive lens will offer a clear image at near, at intermediate distances, and at far away objects.
If you balk at the idea of wearing bifocal spectacles there are multifocal contact lenses and even refractive surgery to eliminate presbyopia.
Related Topics: Slew of New Lenses Act Like Real Eyes, Healthy Diet May Improve Seniors' Vision
Technorati Tags: presbyopia, bifocals, eyehealth
