What is the most likely cause of unilateral visual loss, impaired color perception, and a relative afferent pupillary defect in a 32-year-old woman with 20/60 visual acuity in the affected eye and normal funduscopic examination, suggesting a lesion in which of the following sites: optic nerve, chiasm, geniculate nucleus, occipital cortex, or retina?

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Differential Diagnosis for Visual Loss in a 32-year-old Woman

Single Most Likely Diagnosis

  • Optic Neuritis (D) Optic nerve: The patient's symptoms of sudden visual loss, blurred vision, mild aching discomfort, and decreased color perception in one eye are classic for optic neuritis. The decreased, sluggish pupillary constriction when light is shined in the affected eye (a relative afferent pupillary defect) further supports this diagnosis.

Other Likely Diagnoses

  • Ischemic Optic Neuropathy (D) Optic nerve: Although less common in a 32-year-old, ischemic optic neuropathy could present with similar symptoms, especially if there's an underlying vascular condition.
  • Retinal Detachment (E) Retina: While the funduscopic examination shows no abnormalities, a retinal detachment could potentially cause sudden visual loss and should be considered, especially if symptoms worsen.

Do Not Miss Diagnoses

  • Pituitary Apoplexy (A) Chiasm: Although less likely given the unilateral presentation, pituitary apoplexy can cause sudden visual loss and is a medical emergency requiring prompt intervention.
  • Giant Cell Arteritis: This condition can cause ischemic optic neuropathy and is a medical emergency. It's less likely in a 32-year-old but should be considered in the differential due to its potential for severe consequences if missed.

Rare Diagnoses

  • Occipital Cortex Lesion (C) Occipital cortex: A lesion here would more likely cause homonymous hemianopia (visual field loss on the same side in both eyes) rather than the unilateral symptoms described.
  • Geniculate Nucleus Lesion (B) Geniculate nucleus: Lesions at this site are rare and would likely cause more complex visual disturbances rather than the straightforward visual loss described.
  • Chiasmal Lesion (A) Chiasm: While a chiasmal lesion could cause visual disturbances, it typically presents with bitemporal hemianopia, which is not consistent with this patient's unilateral symptoms.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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