Final answer:
A service member should be referred to optometry when their visual acuity falls below the standard required for their duties, commonly if it is worse than 20/40. This ensures they receive proper evaluation and the necessary corrective lenses or treatment for optimal vision.
Step-by-step explanation:
The question asks at what point a service member should be referred to optometry if their visual acuity is below a certain threshold. Testing vision often involves the use of the Snellen chart to determine visual acuity. For example, someone with a 20/60 vision can see at 20 feet what a person with normal acuity can see at 60 feet. A referral to optometry is generally based on whether the individual's visual acuity falls below the required standards for their role or activities. While the question does not provide a specific threshold for referral, real-world guidelines often suggest referral if acuity is worse than 20/40, as it may indicate a need for corrective lenses or further eye health evaluation.
Regarding the related examples provided, the power of a contact lens needed to correct the vision of a severely myopic patient can be calculated using the focal length and power relationships. The typical power range for an eye from distant to close vision is an increase from 50.0 diopters (D) to 54.0 D. Myopia correction involves a negative power lens to adjust the focal point such that distant objects can be seen more clearly.