The cranial nerve implicated is of course the optic nerve. The neighbor’s symptoms include progressively worse double vision, and a drooping right eyelid that is abducted and depressed—a condition known as ptosis. The right eye also has greater dilation than the left. A cranial nerve injury is suspected, possibly a result of the neighbor’s recent fall. As the optic nerve (cranial nerve 2) leaves the eye, it passes through the optic chiasm and the optic tract to the oculomotor nerve (cranial nerve 3) (Coleman, 2017; “Cranial Nerves,” n.d.). Because of the primary symptom of ptosis, the cranial nerve 3, the oculomotor nerve, has likely been damaged. If the patient also suffered damage to additional cranial nerves like cranial nerve 5, then it is also possible she would be experiencing dry eyes, as this is the nerve that enables the release of tears from the lacrimal gland (Coleman, 2017). If the patient is completely unable to close the right eye, then she might have Bell’s palsy. However, her symptoms do not seem to include Bell’s palsy, as she only has a drooping eye and rest of the face is unaffected.

Because the patient is also indicating the presence of persistent and worsening double vision, tests are required to see if myasthenia gravis is the issue. The fall might have exacerbated the precondition. Myasthenia gravis is a relatively rare condition, which is why further tests would be required. It would also mean the patient had been experiencing other symptoms not related to the eye itself, which is why it is unlikely this is the case. The position of the right eye, being both slightly dilated and drooping, most likely indicates aponeurotic ptosis, which is more common among people in the neighbor’s age group (“Aponeurotic Ptosis,” n.d.). Damage to the oculomotor nerve causes this type of eyelid drooping.

References

“Aponeurotic ptosis,” (n.d.). American Academy of Opthamology. https://www.aao.org/bcscsnippetdetail.aspx?id=0c1f71d5-bb52-4683-bc9d-e04fff8f32d7

Coleman, R. (2017). Cranial nerves that affect the eye. https://www.livestrong.com/article/84669-cranial-nerves-affect-eye/

“Cranial Nerves,” (n.d.). https://faculty.washington.edu/chudler/cranial.html