Dioptric defects
Content:
Short-sightedness
Typical symptoms of short-sightedness are lack of acute vision and blurry vision from a distance. Therefore, the affected person squints his eyes in order to get an acute image through a narrowed slit – hence the term myopia, which in Latin means “closed eyes.”
Long-sightedness
A typical symptom of long-sightedness (hypermetropia, hyperopia) is poor visibility of nearby objects. It usually occurs at birth and can be undetected in childhood. Sometimes long-sighted children have problems with reading as well as with strabismus. In older age other symptoms occur – blurry vision, tearing, tiredness, eye pain, or headaches, which are more intense in the evening and after increased physical or mental exertion.
Astigmatism
A typical symptom of astigmatism is lack of sharpness in both near and distant vision. The affected people cannot see clearly the contrasts among horizontal, vertical, or slanted lines – e.g. they exchange similar characters such as numerals 0, 3 or 8 or letters H, M, or N. Other symptoms are eyestrain or headache.
Presbyopia
Typically, presbyopia is presented by difficulties in reading at near distances – the affected person helps himself by putting the text at a greater distance, by tilting his head back or reading in brighter light. When looking from near objects into the distance the vision gets foggy, even headache and eyestrain can occur. The mentioned symptoms are more distinct in people who need to concentrate for long periods on near objects – e.g. a computer monitor.
Higher-order aberrations (HOAs)
Abnormalities and irregularities in the optical system of the eye might have a significant impact on the quality of vision, for example worsening of vision in the dark or at dusk, double vision etc.
