Injuries to the macula or fovea centralis typically affect vision by producing which of the following?
- Bitemporal hemianopsia
- Nyctalopia (night blindness)
- Scintillating scotomas
- Mild loss of visual acuity
- Severe loss of visual acuity
the answer is below…
The United States Medical Licensing Examination, or USMLE for short, is a three-part licensing examination that is required in order to receive a license to practice medicine within the United States.
The USMLE assesses a physician’s ability to apply knowledge, concepts, and principles, and to determine fundamental patient-centered skills that are important in health and disease and that constitute the basis of safe and effective patient care.Examination committees composed of medical educators and clinicians from across the United States and its territories prepare the examination materials each year.
This exam is designed by the Federation of State Medical Boards and the National Board of Medical Examiners to determine whether or not an individual understands and can apply the knowledge necessary to practice medicine safely and intelligently.
The USMLE is actually comprised of three different exams that are referred to as steps, which examine the individual’s knowledge of specific topics related to the field of medicine such as basic science, medical knowledge, medical skills, clinical science, and the application of all of these skills and areas of knowledge in the medical field.
All three steps of the USMLE include a series of computerized multiple-choice questions, but the format of the exam and the information covered in each multiple-choice section is different for each step of the USMLE. The USMLE Step II also has a clinical skills portion that examines an individual’s ability to work with real patients and the USMLE Step III has a computerized patient simulation portion in addition to the multiple-choice section of the exam. In order for an individual to receive a license to practice medicine, the individual must pass all three steps of the USMLE.
The answer is e, Severe loss of visual acuity (PCP). 
The cones of the retina are packed into the macula, and the primary focus of the lens is at the macula. The macula is therefore responsible for visual acuity. Therefore, injury to the macula results in significant loss of acuity, often with preservation of peripheral vision. The macula is usually evident on ophthalmologic examination because it normally reflects a point of light that can be seen through the ophthalmoscope. It is located 3 to 4 mm temporally from the optic disc. Bitemporal hemianopsia is seen in injury to the optic chiasm, as from pituitary tumors. Nyctalopia (night blindness) is seen in retinal degeneration (e.g., retinitis pigmentosa), vitamin A deficiency, and color blindness. Scintillating scotomas are the classic signature of the migraine aura.