Final answer:
A nurse evaluates the effectiveness of bifocals in improving myopia and presbyopia by assessing the patient's near and distant vision, as bifocals are intended to correct vision at both ranges.
Step-by-step explanation:
A nurse can evaluate the improvement of a patient's myopia and presbyopia with the use of bifocal lenses by assessing for both near and distant vision. Myopia, or nearsightedness, is when a person has difficulty seeing distant objects clearly, and presbyopia is a condition often related to aging, where the eye loses its ability to focus on close objects. Since bifocals are designed to correct both conditions by providing different lens powers for distance and near vision, checking the vision for both ranges can help determine the effectiveness of the bifocals. This does not directly relate to the strength of the eye muscles, cloudiness in the eye lenses, such as cataracts, or changes in intraocular pressure, which affect different aspects of eye health and vision.