How to Choose Eyeglasses for Myopia Combined with Astigmatism

Generally, when myopia or hyperopia occurs, corrective eyeglasses can be worn to improve vision, enabling clearer sight of distant or near objects. Astigmatism is a type of refractive error in the eye, commonly associated with irregular curvature of the cornea. When astigmatism is present, symptoms such as reduced visual acuity and visual fatigue often occur. So, how are glasses prescribed for patients with both myopia and astigmatism?

How Are Glasses Prescribed for Myopia Combined with Astigmatism?

Prescribing glasses for concurrent myopia and astigmatism is relatively complex and requires integrated consideration of astigmatic power (cylinder), axis, and myopic spherical power. If the astigmatism is mild—less than 0.50 D—or negligible, it can be directly incorporated into the spherical lens during lens fabrication; thus, no separate cylindrical lens adjustment is needed. However, if the cylindrical component is relatively large, integrating spherical and cylindrical corrections into a single lens becomes technically challenging. Some cases involve mixed astigmatism, where the cylindrical power may even exceed the spherical power. Based on the refraction findings, appropriate adjustments—including adding, subtracting, or converting refractive values—are made to achieve an optimal prescription. Prior to finalizing the prescription or lens selection, trial fitting is essential. During this process, a comprehensive evaluation using a phoropter is recommended to precisely assess spherical and cylindrical powers—and even calculate their differences—to ensure an ideal lens match.

When prescribing glasses for combined myopia and astigmatism, both spherical lenses (to correct myopia) and cylindrical lenses (to correct astigmatism) can be incorporated into the same pair of spectacles. Typically, full correction of myopia is recommended, while the degree of astigmatic correction varies depending on the severity of astigmatism. In cases of low astigmatism with good uncorrected visual acuity and no significant visual fatigue, cylindrical correction may be omitted. Conversely, if astigmatism substantially impairs vision and causes noticeable visual fatigue, cylindrical correction should be included in the prescription.

When selecting cylindrical lenses for astigmatism, it is advisable to start with the lowest possible power and gradually increase only to the minimal level that provides clear, comfortable vision for the patient. We hope this explanation proves helpful.