History of Present Illness (HPI)

The patient is a 66-year-old male presenting with a 3-day history of swelling, discharge, and pain in his left eye. He reports that something hit his eye 3 days ago but cannot recall what it was. The symptoms have been persistent since the incident.

Physical Examination (PE)

The physical examination of the patient reveals swelling and discharge in the left eye. A wood lamp exam was performed, which did not show any foreign body or corneal abrasion.

Differential Diagnosis

Single Most Likely Diagnosis

• Blepharitis or Conjunctivitis: Given the symptoms of swelling, discharge, and pain in the eye following a traumatic incident, an infection such as blepharitis or conjunctivitis is highly plausible. The absence of a foreign body or corneal abrasion on the wood lamp exam does not rule out these conditions.

Other Likely Diagnoses

• Corneal Ulcer: Although the wood lamp exam did not reveal a corneal abrasion, a corneal ulcer could still be a possibility, especially if the initial trauma caused a small defect in the cornea that became infected.
• Orbital Cellulitis: This condition, an infection of the tissues surrounding the eye, could be a consideration given the swelling and pain, especially if the trauma compromised the integrity of the skin or conjunctiva, allowing bacteria to enter.

Do Not Miss Diagnoses

• Endophthalmitis: This is a severe infection within the eye that can result from trauma. It is less likely but critical to diagnose early because it can lead to severe vision loss or blindness if not promptly treated.
• Retinal Detachment: Trauma to the eye can cause retinal detachment, which is an emergency requiring immediate attention to preserve vision.

Rare Diagnoses

• Sympathetic Ophthalmia: A rare, inflammatory condition that can occur after penetrating eye trauma, leading to inflammation in the uninjured eye.
• Siderosis Bulbi: If the object that hit the patient's eye was metallic (e.g., iron), there's a possibility of siderosis bulbi, a condition caused by the deposition of iron intraocularly, leading to various ocular complications.

ICD-10 Codes

• H00.019: Unspecified conjunctivitis, left eye
• H02.219: Unspecified blepharitis, left eye
• These codes are preliminary and may change based on the final diagnosis after further evaluation and testing.

This differential diagnosis is guided by the patient's symptoms and the physical examination findings, considering both common and less common conditions that could explain the patient's presentation.