GP lens eye Rounds

HIGH ASTIGMATISM: Evaluation

Jessica Conroy OD, FAAO

When fitting a toric lens on a highly toric cornea, evaluation of a toric GP lens should be same as with a spherical GP on a spherical cornea¹

• Utilize sodium fluorescein (NaFl) and cobalt blue filter on biomicroscope to evaluate lens-to-cornea fitting relationship²
  • Note: Utilization of a wratten filter will help to highlight the NaFl pattern
• Descriptions²
  • Areas where NaFl is present in the tear layer appear to be GREEN
  • Areas where NaFl is absent (or is too thin to detect) appear BLACK
• Alignment Fit: observed when lens evenly contours cornea²
  • Center: light, even tear pooling
  • Mid-Periphery: thin, even, circular band of bearing
  • Edge: even tear pooling to allow for sufficient tear exchange

Sources

1. 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.
2. Bennett ES, Sorbara L, Kojima R. Gas Permeable Lens Design, Fitting, and Evaluation. In Bennett ES, Henry VA. Clinical Manual of Contact Lenses, 5th ed. Wolters Kluwer, Philadelphia, PA, 2020:134–185.