Cycloplegia is loss of the power of accommodation with inhibition of a ciliary muscle. We obtain in this way the smallest refraction of the lens and make it possible to determine the presence and size of the particular refractive error in cycloplegia by using cyclopentolate. Cyclopentolate is a synthetic anticholinergic drug and antagonist of the muscarine receptors. If applied in the eye, it blocks the effect of cholinergic stimulation on the sphincter pupillae muscle and ciliary muscle. It provokes severe mydriasis (dilation of the pupil) and cycloplegia (paralysis of the accommodation). Cyclopentolate has been used occasionaly in diagnostic purposes: defining ocular refraction and in ophthalmoscopy. This is the prospective study which included 200 children (400 eyes) aged 3-18 years, carried out in one ambulatory ophthalmological examination. The results were analysed using standard statistical methods. The most often refractive error in the examined group of children is hyperopia with hyperopic astigmatism, then myopia with myopic astigmatism and mixtus astigmatism are the most often in the oldest group of children. The mean value of corneal astigmatism on the right eye was 1.24 D, on the left eye 1.23 D. Anisometropy was found in 40% children. The presence of myopia, myopic and astigmatism mixtus tended to increase, and hyperopia and hyperopic astigmatism tended to decrease toward older groups of children. Refractive error could result in a poor development of visual acuity, causing amblyopia and strabismus, and because of that represents an important public health problem. As one of amblyogenic risk factors in children, it can be prevented with screening program and appropriate treatment, thus providing prevention of amblyopia as one form of blindness.