Anisotropia is a condition in which there is a difference in refractive power between the two eyes, and there are congenital factors and factors influenced by the environment. If anisometropia is left untreated, deterioration of binocular vision and manifestation of strabismus may occur, impairing QOL. In this article, I will outline the frequency, age-related changes, and methods of correcting refractive and axial anisometropia for myopic anisometropia. Evaluation methods for aniseikonia (macropsia) due to epiretinal membrane, and the principle of the size lens to correct aniseikonia are added.

Prescribing eyeglasses in clinical practice is fundamental to ophthalmology. However, with the advent of various refractive correction methods, ophthalmologists have fewer opportunities to be involved in prescribing eyeglasses. It is necessary to prescribe eyeglasses not only based on ophthalmological optics, but also with an eye for ocular changes due to ocular diseases and aging. The basis for all corrective measures is eyeglasses. Without the ability to prescribe eyeglasses, it is impossible to correctly select other refractive correction methods. This article explains the basics of clinical ophthalmology necessary for prescribing eyeglasses.

From the viewpoint of prescribing glasses with an emphasis on comfort, the necessary visual function examinations will be described. In particular, examination of refraction and examination of accommodation are described in detail as the basic examinations.

Since the accommodative analyzer uses an autorefractometer (autoref), the measurement principle and measurable range conform to the specifications of the autoref. Therefore, understanding the specifications of the autoref and learning how to operate it appropriately are the basis of refractive and accommodation examinations. In addition, the examination of subjective refraction is performed according to a flowchart using accurately auto-ref values.

As a prerequisite for prescribing eyeglasses, we believe that eyeglasses should be prescribed by an ophthalmologist who is familiar with anatomy and ocular physiology, and who understands refraction and accommodation.

Various textbooks^{1) 2) 3)} have been published on the geometrical optics of spectacle lenses. In this paper, we have added information from the standpoint of eyeglass lens manufacturers and reorganized these textbooks. Spectacle lenses differ from other vision correction lenses in that the optical characteristics of the lens periphery must be considered. For this reason, off-axis aberration theory and information on the eyeball optical system are required for actual lens design, but this paper does not deal with them. We hope that you will enjoy reading it as an introductory knowledge of lens geometric optics.

Since the introduction of the first progressive-power lens in 1959, lens design and processing technology has progressed considerably. Notably, the introduction of the back surface progressive-power lens in 1997 brought about a major change in the concept of lens design and processing. After receiving an order, the optimal optical design is established for each lens, and the technique of creating a free-form curved surface without using a mold is passed down to the current individual lenses. Individual lenses that aim for optimal optical performance in the as-worn position may have values different from the prescribed power when measured by a focimeter. To fully demonstrate the performance of spectacles, people involved in making spectacles, such as ophthalmologists, orthoptists, opticians, spectacles dealers, lens manufacturers, and equipment manufacturers must share technical background knowledge of new progressive-power lenses and divide roles appropriately.