Quadrant Specific Designs Explained.

Quad Sym designs allow for 4 different base curves and 4 different edge lifts. One analogy to explain Quadrant Specific Technology is to a pie. Cut a pie into 4 quarters and one of those pieces represents one Quad Sym Base Curve. If we deal only with the crust on that piece of pie, it is a Quad Sym Peripheral Curve. And the practitioner can get both separate base curve treatments with different peripheral curve treatments.

How To Call Out Quadrants.

The quadrants are referred to as Quad 1, Quad 2, Quad 3 and Quad 4. The Quads start at 4:30 to 1:30 and go around the clock, counter-clockwise just as we refer to degrees of 0 to 180. Quad 1 = 4:30 to 1:30, Quad 2 = 1:30 to 10:30, Quad 3 = 10:30 to 7:30 and Quad 4 = 7:30 to 4:30.

Fitting Criteria.
LDI employs a modified topography / trial lens fitting methodology. Start with a trial lens of Dyna Cone Plus or Dyna Intra-Limbal. Try to get at least one quadrant aligned and make notes as to what is happening in the other 3 quadrants. (i.e. Pooling, touch, etc.) Perform over refraction. Get these details along with axial topography map to LDI. Files sent by email should be in PDF files or JPEG files to This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Rotation Issues.
These designs tend to locate with the flat-to-flat and steep-to-steep areas. A half diopter of prism is standard, but up to 2 diopters can be incorporated to stop excessive rotation. Each lens has marks midway in Quads 1 and 3. Therefore, the marks should be at 3 and 9 o’clock on the eye. Always make note of where the rotation dots locate. The transition areas between Quads are mono-centric. No visual “jump” occurs with these designs. Each front radius matches the base curve radius to achieve a given power.