Why should children dilate their pupils for optometry?

Abstract: eyeball diopter = corneal curvature + eyeball length + lens diopter. The corneal curvature and eyeball length are determined by the shape of the eyeball. Generally, in adults aged 18 ~ 40, the eyeball has been fully developed and mature, and this shape is unchanged. The

human eye is like a camera. To see objects clearly, it needs a refractive system – “lens” that meets the focus line. If the lens does not focus well, the photos taken or what you see are blurred. The diopter of

and

reflects the focus of the “lens”, which is composed of three factors: corneal curvature, eye length and lens diopter. That is: eyeball diopter = corneal curvature + eyeball length + lens diopter. The corneal curvature and eyeball length are determined by the shape of the eyeball. Generally, in adults aged 18 ~ 40, the eyeball has fully developed and matured, and this shape is unchanged. The diopter of the lens will change accordingly with the distance we see the object, so the diopter of the eye will also change with the distance we see the object, so that the focus of eye imaging always falls on the retina to obtain a clear image. When

and

regulate quiescence, the lens is in the lowest diopter state without change. The ocular diopter of emmetropia is 58.64d. When the individual’s ocular diopter is greater than that of emmetropia, the convergence force of light is too strong, and the focus falls in front of the retina to form myopia. The difference between the individual’s diopter and this standard is the amount of myopia. For example, the individual eye diopter is 60.64, Myopia is estimated to be 60.64-58.64 = 2D (myopia 200 degrees); on the contrary, when the individual’s eye diopter is less than that of emmetropia, the convergence force of light is insufficient, and the focus falls behind the retina to form hyperopia. The difference between the individual’s diopter and this standard is the hyperopia. For example, the individual’s eye diopter is 56.64, and myopia is estimated to be 56.64-58.64 = – 2D (hyperopia 200 degrees).

because the diopter of the lens is a variable, when we judge myopia, we need to “remove and adjust the lens and be in the lowest diopter state”, that is, the diopter of the lens will not change. Children’s lens is difficult to be in the “unchanged” state of the minimum diopter due to their strong adjustment. Therefore, it is necessary to force the lens to be in the “unchanged” state of the minimum diopter through drugs to “dilate the pupil and paralyze the ciliary muscle”.