Final answer:
The question appears to be about the measure of corneal displacement in applanation tonometry, but this detail is not provided. Instead, the provided text focuses on the optical power of the tear layer for persons with specific farsighted and nearsighted contact lens prescriptions.
Step-by-step explanation:
The question asks about applanation tonometry, a method commonly used to measure intraocular pressure (IOP) in the eyes by flattening a part of the cornea. However, the specifics of corneal displacement in mm during applanation tonometry are not mentioned in the provided text and are beyond the scope of the details given.
Instead, the text addresses the optical power of the tear layer in diopters when considering the correction provided by contact lenses in individuals who are mildly farsighted or nearsighted. For a person with a prescription of 0.750 D and a near point of 29.0 cm, as well as for a person with a prescription of -4.00 D and a far point of 22.5 cm, the question pertains to finding the power of the tear layer between the cornea and the lens for ideal correction.