Understanding JCC in Phoropter: A Guide to Its Purpose and Function

Cross cylinder examination, also known as Jackson's cross cylinder or JCC, is a precise and essential technique employed in ophthalmological practice to enhance the accuracy of prescribing corrective lenses for astigmatic patients. Astigmatism is a refractive error that arises from an irregular corneal shape, resulting in distorted vision at both near and far distances. By introducing this specialized optical device during the refraction process, eye care professionals can finely adjust and refine the axis and strength of the astigmatism, leading to improved visual acuity and clarity for patients. This examination is a fundamental component of the phoropter, a versatile and indispensable instrument used in comprehensive eye examinations. The incorporation of JCC in the phoropter allows eye care professionals to precisely measure, diagnose, and correct astigmatism, resulting in optimal visual outcomes for individuals experiencing this refractive anomaly.

What Power Is JCC in Phoropter?

During a routine examination, a patient may utilize a phoropter, a device commonly used to determine an individuals refractive error and correct vision. Within the phoropter, there’s a specific power known as JCC, which stands for Jackson Cross Cylinder. The JCC is a specialized lens that incorporates both sphere and cylinder powers.

The JCC is designed to fine-tune the prescription, helping the optometrist or ophthalmologist determine the most accurate lens power for the patient. It’s considered a spherical equivalent plano-powered lens, meaning it’s no refractive power in it’s neutral position. The JCC contains power increments typically measured in increments of ±0.25 or ±0.50.

It’s inclusion in the examination process ensures that patients receive optimal vision correction based on their unique visual needs.

How Does the JCC Power Affect the Astigmatism Correction for the Patient?

  • The JCC power has a significant impact on the astigmatism correction for the patient.
  • By adjusting the JCC power, the amount of astigmatism correction can be customized for each patient’s specific needs.
  • A higher JCC power can provide greater correction for higher levels of astigmatism.
  • Conversely, a lower JCC power may be sufficient for patients with lower levels of astigmatism.
  • The selection of the appropriate JCC power requires careful assessment by an eye care professional.
  • The goal is to find the optimal JCC power that provides the best visual acuity and astigmatism correction for the patient.
  • It’s important to note that the JCC power may need to be adjusted over time as the patient’s astigmatism changes.
  • Regular follow-up appointments with the eye care professional are necessary to monitor and fine-tune the JCC power for optimal results.
  • Overall, the JCC power plays a crucial role in maximizing the astigmatism correction and improving the patient’s visual clarity.


This examination aids in the precise determination of both the strength and axis of astigmatism, allowing for better visual correction and improved patient outcomes. By fine-tuning the astigmatic refraction, JCC optimizes the prescription for individuals, ensuring that their vision is accurately corrected. As a crucial component of phoropter technology, the JCC examination plays a significant role in the diagnostic and treatment processes, contributing to better patient care and satisfaction.