Presbyopia is a vision condition caused by the eye’s natural aging and thus is a common problem bothering a vast majority of the elderly over 40 years old. People with this condition have a progressively diminished ability to focus on near objects. Until now, the exact reason of presbyopia is still uncertain, even if most eye doctors believe it is a loss of elasticity of the eye’s natural lenses. Like grey hair and wrinkles, presbyopia is an inevitable condition in most people. Most individuals begin to notice this problem between the ages of forty and fifty. An obvious symptom is the gradual decline in focusing on near objects. Thus presbyopic patients usually hold reading materials intentionally at an arm’s distance. It is quite necessary to get this problem treated. And reading glasses and half eye glasses are the most common solution.
Reading glasses in different forms are also prescription eyeglasses. Those traditional ones are single-vision ones, while modern lens technologies have made multifocal reading glasses a reality. Here we focus on the first category. With the help of a pair of regular reading glasses, presbyopic patients are able to see clearly materials at a normal distance. It is no longer necessary to hold a book or newspapers as far as possibly. Ordinary reading glasses have a single power in the whole part of the lenses. But half eye glasses or half-eye reading glasses are different that their lenses are half-powered. In a typical design, only the lower half of the lenses is corrective, leaving the top half to be Plano.
What is the advantage of half eye spectacles over the regular ones? In fact, they are suitable in different circumstances. Full reading glasses can function well during long-term reading tasks, which require few switches of visual distance. But during intermittent reading, these glasses are inconvenient. Half eye glasses serve better in this case. When it is necessary to switch focus onto a distant object, the wearer can simply see through the top section of the lenses. Clear reading vision can be got by looking slightly down.