The Jackson crossed cylinder: historical perspective.

The crossed cylinder lens has been an integral part of clinical refraction for more than 100 years. Although the use of the crossed cylinder in refraction has been scrutinized throughout the 20th Century, it remains the most commonly used technique of clinical refraction for astigmatism. This paper provides a historical perspective of the evolution of the Jackson crossed cylinder technique through a literature review that begins at the mid-19th Century. This review addresses the utilization of the crossed cylinder lens in clinical refraction since its introduction, and the attempts to evaluate its validity and reliability.