2.50DS is not a visual acuity, but an indication of how much refraction there is, with a plus or minus to determine refractive status. If it is -2.50DS, it means 250 degrees of myopia, and if it is +2.50DS, it means 250 degrees of hyperopia. At the time of optometry, there will be some checking data on the optometry sheet, where D stands for refraction, S stands for spherical lens, and DS is the number of degrees of myopia or hyperopia. If the DS value is positive, it means hyperopia, and if the DS value is negative, it means myopia. Myopia and hyperopia refer to the condition where parallel rays of light enter the eye and pass through the refractive medium, but fall behind or in front of the retina, and cannot be clearly imaged on the retina. 250 degrees of myopia or hyperopia, which affects normal vision, should be corrected by wearing frames, corneal contact lenses or surgery, etc. The specific method of correction should be consulted with your doctor. Specific correction methods should be determined after consulting with a medical professional.