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Limbal Relaxing Incision Calculator


Johnson & Johnson Surgical Vision, Inc. does not engage in the practice of medicine and these clinical tips are not a substitute for appropriate medical education and training or for the exercise of independent medical judgment. Each medical situation should be considered unique to each patient and all treatments individualized accordingly based on the respective physician’s medical judgment. Johnson & Johnson Surgical Vision, Inc. does not (1) warranty the accuracy or completeness of any of the clinical tips, or (2) endorse or recommend any particular technique unless and to the extent such technique is expressly stated in the product labelling.

Using the LRI Calculator

The LRI calculator is designed to help you provide minor astigmatism correction to cataract patients. Developed to assist limbal relaxing incision planning for phacoemulsification cataract surgery, the LRI calculator provides simple calculations specifically for manual LRIs.


Remember, the LRI calculator is for manual incisions only.

  1. First, select your viewing preferences for the preview image.
    • Degree-based versus clock-based scale
    • Superior versus temporal perspectives
  1. Input your information and your patient’s information.
  1. Select your preferred nomogram: Donnenfeld (DONO) or Nichamin Age and Pachymetry Adjusted (NAPA).
  1. Fill in the patient’s measurements.
    • Fill in the measurement for surgically induced cylinder or astigmatism (SIA) and incision location (IL) when performing phaco incisions
  1. Review the patient’s information, and click "continue" to see a preview of incision locations.

For additional information about LRIs or intraoperative astigmatism correction, explore the LRI calculator page.