Traumatic Optic Neuropathy (TON)

Symptoms

Vision loss
Visual field defects
Decreased color perception

Physical examination

orbital trauma or fracture (soft tissue edema, hematoma, ecchymoses, step-off on palpation of orbital rim)
Decreased visual acuity and a relative afferent pupillary defect (RAPD) (in unilateral cases) are also seen.
On fundoscopy, CD ration may be normal, but signs of optic atrophy may be seen 3-6 weeks after trauma

Signs

Decreased visual acuity
Decreased color vision
Afferent pupillary defect (KEY!!!!!)
1. (RAPD POSITIVE : ในภาวะปกติ pupil จะต้องเท่ากัน แต่ถ้าส่งไฟ แล้วย้ายไปอีกข้าง แทนที่มันจะหด มันกลับขยาย)
Visual field deficits
Optic disc edema but often a normal optic nerve initially (retrobulbar optic neuropathy) followed by optic atrophy later

ต้องแยกกับ Nerve 3 palsy

Clinical diagnosis : history and physical exam findings.

It is important to obtain neuroimaging, usually a CT of the orbit with coronal and axial thin sections (1 mm) through the optic canal are crucial to visualize the optic nerve as well as the optic canal and carefully evaluate for evidence of fracture. This can help assess for compression of the optic nerve by a hematoma or bony fragments impinging on the optic nerve, which would require urgent surgical intervention.

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