MYOPIA AND ITS TREATMENT IN OPTOMETRIC PRACTICE

Abstract

The change in the direction of light rays passing from one medium to another is defined by the concept of refraction. The refraction of the human eye can be defined as a term for all normal and abnormal bending of light as it passes through the ocular media to reach the retina as a light ray. Along its path, this light ray is subject to several phenomena, such as refraction, diffraction, reflection, and absorption. Among all the properties of light, optometric practice focuses mostly on refraction and the corrective lenses we use to address it. To understand refraction, we must start from the beginning by understanding the types of refraction found in humans. Refraction can be defined by two concepts: emmetropia and ametropia. Emmetropia refers to a normal eye where parallel light rays entering the eye focus directly on the retina. For an eye to be emmetropic, it must have a normal correlation between the axial length of the eye and the refractive power of the ocular media through which the light ray passes, such as: the cornea, the aqueous humor that fills the anterior chamber, the lens, and the vitreous body. When this correlation is normal and complete, the light rays are refracted at the macula of the retina, producing a clear and sharp image. In contrast to emmetropia, there is ametropia, where light rays do not focus on the macula, resulting in a refractive anomaly. A refractive anomaly is defined as a focus that occurs either in front of the retina—resulting in myopia (nearsightedness), or behind the retina, resulting in hypermetropia (farsightedness). Ametropia can be axial or refractive. Axial ametropia is a problem with the dimensions of the eye: a longer eye results in myopia, while a shorter eye results in hypermetropia. Refractive ametropia involves problems with the refractive power of the ocular media, such as a curved cornea or lens with varying strength in different meridians, leading to astigmatism. Children are born hypermetropic, and with growth, the axial length changes and the ocular media adjust, eventually leading to emmetropia. In adults, the axial length does not change, but the refractive power of the ocular media can change, leading to hypermetropia or myopia, for example in cases involving the development of cataracts in the intraocular lens. New statistics show an increasing frequency of astigmatism in young children, and any uncorrected astigmatism can lead to myopia due to the blurred vision a child experiences when looking at distant objects. The most common refractive anomaly is myopia (nearsightedness), which in most cases either remains stable or progresses, but very rarely regresses. Myopia, as a refractive anomaly that allows good near vision but poor distance vision, is a major issue for normal human functioning. However, its control and treatment have significantly evolved and improved through modern diagnostic equipment and corrective lenses that aid in this process. Still, in many cases, myopia progresses uncontrollably, which is due to changes in our habits in today’s “new normal” lifestyle that involves increased use of electronic devices at close range. In recent years, myopia has become one of the most progressive refractive anomalies encountered in optometric practice, yet public awareness of the potential consequences of undiagnosed and untreated myopia remains very low. Treatment requires persistence and consistent checkups, which every person with myopia should undergo throughout the year.