American Board of Opticianry (ABO) Practice Test 2026 – The All-in-One Guide to Master the American Board of Opticianry Exam!

The direction of a prism in reverse slab off is verified by looking downward, towards the ground. This is because the reverse slab off technique is used to reduce the amount of prism effect at the bottom of a pair of eyeglasses, so checking the direction in which the prism is facing downwards is important. The other options given may be incorrect for various reasons. The apex of the cornea is not necessarily related to the verification of prism direction. The wet/dry option may be referring to a different aspect of prism measurement and is not directly related to the direction. The dot beneath the fitting cross may not always be present or visible and may not be the most accurate point to verify prism direction. Ultimately, the most effective way to verify the direction of prism in reverse slab off is by looking downward.