The right refractive cylinder lens C is an indication of the amount of astigmatism in the right eye. Where C is short for cylinder, a lens with a rounded surface that is commonly used to correct astigmatism. Astigmatism occurs when the refractive system fails to focus parallel rays of light at the same location on the retina as they pass through the eye due to differences in the refractive power of the eye at different meridian lines. The refractive column C of the right eye indicates that astigmatism may be present in the right eye, and its value reflects the degree of astigmatism; if the value is preceded by a “+” it indicates hyperopic astigmatism, and if it is preceded by a “-” it indicates myopic astigmatism. Also visible is A, which reflects the direction of the astigmatism. When the presence of astigmatism affects vision, it is recommended to consult a medical professional for standardized optometry.