What is indicated by a difference of 2.00 diopters or more between the O.D. and O.S. prescription?

A difference of 2.00 diopters or more between the right eye (O.D.) and the left eye (O.S.) prescription indicates anisometropia. This condition refers to a significant inequality in the refractive power of the two eyes, which can lead to issues such as discomfort, headaches, or difficulty with depth perception. When one eye requires a much stronger or weaker lens compared to the other, it can affect visual processing and may necessitate specialized lenses or treatments to help balance the visual experience.

In contrast, the other options refer to different visual conditions not directly related to the disparity in diopter strength between the eyes. Aniseikonia relates to perceptual differences in the images seen by the two eyes but is specifically about image size rather than refractive error. Presbyopia is a condition related to aging and affects the eye's ability to focus on close objects. Astigmatism is caused by an irregular shape of the cornea or lens that leads to blurred vision but doesn't specifically involve the differential refractive error between the two eyes. Thus, the presence of a significant difference in prescription between the eyes specifically points to anisometropia.