Contact Lens Registry Exam Practice 2026 – Comprehensive Test Prep

To extend the range of a keratometer to 61.00 D, an auxiliary power lens is used to add to the capability of the device. In this scenario, we’re interested in determining the appropriate additional power needed based on the standard range of a keratometer, which typically allows for measuring corneal curvature up to around 60.00 D.

The calculations to select the appropriate auxiliary lens involve adding the power of the lens to the maximum measurement capability of the keratometer. In this case, the standard maximum keratometer measurement of 60.00 D would require an additional 1.00 D to reach the desired reading of 61.00 D.

Thus, using a +1.00 D auxiliary lens effectively extends the range of the keratometer to accommodate the desired measurement, making it the most suitable choice for this particular scenario. This option precisely meets the requirement to achieve the extension of measuring capability to the new maximum of 61.00 D.