If your astigmatism is small, such as -0.25, you may not need to wear glasses. Your vision is hardly affected by this refractive error. It is the weakest type that can be measured. The word "sphere" will appear as a string of numbers on your prescribed glasses. The (-) minus sign represents myopia, which allows objects closer to you to appear clearer.
The Cylinder (CYL) value of the recipe represents the amount of astigmatism correction required. Astigmatism is when the cornea and the lens have different curvatures. The recipe number in this column can be (+) plus or (-) minus depending on whether the astigmatism violates or matches the rules. According to the recipe, the CYL number always appears after the power of the sphere. Our study revealed that adjusting the cylinder of participants without changing the axis did not have a noticeable effect on monocular HCVA or LCVA or visual acceptance. This means that most people can tolerate mild astigmatism undercorrection. On the other hand, correct cylinder placement is important.
If you include astigmatism correction, the prescription will include an axis value. This number represents the angle of the meridian in your eye and is written after the power of CYL. It can range from 90 to 180, with 90 being the vertical longitudinal line of the eye and 180 being the horizontal longitudinal line. The axis value of the glasses indicates the position of the cylindrical refractive power to enhance vision. If the axis value is low, the vision is considered normal, and astigmatism is represented by a large axis value. The axis is important for the eye's ability to focus, regardless of the angle. That is why opticians must be careful of changes in the axis. Significant changes may be a sign that a more serious problem needs to be fixed. This may include other diseases, and these diseases may cause more harm to your eyes.
The distance between the centers of your pupils is called the pupillary distance, abbreviated as PD. It is a very important consideration when buying glasses, especially for high prescription glasses. Usually, PD appears as a single number on your prescription. But it can also appear as two numbers for each eye if you wear multifocal lenses. It is recommended to have a professional evaluate your PD. Many eye clinics offer this service. But you can also measure your PD at home with a ruler, a mirror, and an assistant. The goal is to align the center of your left pupil with the zero marker on the ruler. Measure more than once to ensure accuracy. Many problems, including headaches, blurred vision, and eye strain, can be caused by incorrect PD.
The ADD (Increased Lens Power) value must be considered for both progressive and bifocal lenses. It specifies the power applied to the distance prescription for near distance tasks such as reading and other activities that require near vision. This number may be the same for both eyes or it may be a different value. This depends on your needs. Generally, the higher the number near the plus (+) or minus (-) the stronger the correction. Negative values represent nearsightedness, sometimes called myopia. Positive values represent farsightedness or hyperopia. The PD field, or the millimeters between your pupils, is also included in your prescription. It may be both eyes, pointing to both eyes, or it may be one eye, pointing to only one eye.
