Final Answer:
The expected finding in the child's eye examination is:
a. bilateral red reflex of the eye.
Step-by-step explanation:
Bilateral Red Reflex: The correct option is (a) bilateral red reflex of the eye. This is a normal finding in a child's eye examination. The red reflex is produced by the reflection of light off the vascular layer (retina) in the back of the eye. A bilateral red reflex indicates that light is properly reflecting off both eyes, suggesting normalcy.
Bilateral Red Reflex: The red reflex is an essential part of a routine eye examination in children. It is observed by shining a light into the child's eyes, and the red glow that is reflected back is an indicator of the integrity of the ocular structures. A bilateral red reflex is expected and signifies that light is properly reflecting off the retina in both eyes. This finding helps in ruling out significant abnormalities such as cataracts, tumors, or other serious eye conditions.
In contrast, options (b), (c), and (d) represent findings that would raise concerns:
(b) A black optic disc on ophthalmoscopic examination is not a normal finding and might suggest optic nerve pathology.
(c) Strabismus in a 12-month-old infant could indicate an issue with eye alignment.
(d) A 5-year-old reading the Snellen eye chart at the 20/40 level might indicate a visual acuity concern.
Therefore, the correct and expected finding in a child's eye examination is a bilateral red reflex (option a).