Final answer:
The power of the tear layer between the cornea and the contact lens is generally considered negligible in standard contact lens prescriptions. A -4.00 D prescription indicates a correction for myopia with a far point of 22.5 cm, assuming average conditions of the tear layer.
Step-by-step explanation:
The student's question pertains to the correction of myopia (nearsightedness) with a contact lens. A prescription of -4.00 D suggests that the person's eyes have too much focusing power for distant objects. The far point of 22.5 cm indicates the maximum distance at which the person can see objects clearly without corrective lenses. If we are to find the power of the tear layer between the cornea and the lens, we need to understand the tear layer acts as part of the corrective system, but unless it changes from the normal physiological condition, it is not usually given a separate power in prescriptions. Since tear layers typically have a negligible power, and the question doesn't provide information on abnormal conditions of the tear layer or additional measurements, we would assume the tear layer has negligible power. The contact lens sits directly on the cornea, so under normal conditions, the power of the contact lens would be equal to the required correction for the eye, with the tear layer not impacting the overall power needed to correct vision to normal.
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