What would be the residual astigmatism from the predicted contact lens power for a patient with Refraction: -2.00 -1.00 x 180, Ks: 43.50/44.50@090, BCR: 43.50?

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Prepare for the Gas Permeable Contact Lenses Test. Study with flashcards and practice multiple choice questions. Each question includes hints and explanations. Ace your exam!

Multiple Choice

What would be the residual astigmatism from the predicted contact lens power for a patient with Refraction: -2.00 -1.00 x 180, Ks: 43.50/44.50@090, BCR: 43.50?

The situation hinges on how a spherical gas-permeable lens interacts with the eye’s astigmatism. When the back surface curvature of the GP lens is chosen to match the flatter meridian of the cornea (BCR = 43.50) and the predicted lens power is set to correct the spherical error, the tear lens formed under a spherical GP can neutralize the corneal cylinder. In this case, the corneal astigmatism is 1.00 D at 90, and the refraction has 1.00 D of cylinder at 180. With a spherical GP designed around the flatter meridian, the system can produce no residual cylinder, so the residual astigmatism is effectively plano. That’s why the correct term is Plano (no residual astigmatism).

What would be the residual astigmatism from the predicted contact lens power for a patient with Refraction: -2.00 -1.00 x 180, Ks: 43.50/44.50@090, BCR: 43.50?

Prepare for the Gas Permeable Contact Lenses Test. Study with flashcards and practice multiple choice questions. Each question includes hints and explanations. Ace your exam!

What would be the residual astigmatism from the predicted contact lens power for a patient with Refraction: -2.00 -1.00 x 180, Ks: 43.50/44.50@090, BCR: 43.50?

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