GP lens eye Rounds

HIGH ASTIGMATISM: Custom Lens Parameters

There are numerous fitting philosophies to determine BCR; power is then determined after application of SAM-FAP¹

For example:
- Mandell-Moore Bitoric Lens Guide
- GPLI Toric and Spherical Lens Calculator
  - May recommend fitting base curve radii to induce 0.75D of with-the-rule astigmatism¹
Power of lens is only specified in flat meridian
- Recall that if two powers are specified, this is ultimately a bitoric lens and will be made as such by the laboratory¹
To achieve alignment in the periphery, may need to incorporate toric peripheral curves¹
- General rules for spherical peripheral curves:
  - Secondary curve radius = 1.0mm flatter than the average BCR
  - Periphery curve radius = 3.0mm flatter than the average BCR
- General rules for toric peripheral curves:
  - Secondary curve radius = 1.0mm flatter than BCR
  - Periphery curve radius = 3.0mm flatter than BCR

Bennett ES, Henry VA, Kinoshita BT, Lampa M. Correction of Astigmatism. In Bennett ES, Henry VA. Clinical Manual of Contact Lenses, 5th ed., Wolters Kluwer, Philadelphia, PA, 2020:388–439.