A patient presents with scleral redness after an insect hit the eye and associated eye pain. What is the diagnosis and appropriate treatment?

Diagnosis: Traumatic Conjunctivitis with Possible Corneal Abrasion

This patient most likely has traumatic conjunctivitis with possible corneal abrasion from the insect impact, and should be treated with a broad-spectrum topical antibiotic (such as moxifloxacin 0.5%) to prevent secondary bacterial infection, along with symptomatic management including cold compresses and oral analgesics.

Clinical Reasoning

The presentation of scleral redness, eye pain, and history of insect trauma points to mechanical injury to the ocular surface. The key diagnostic considerations are:

Primary Diagnosis

• Traumatic conjunctivitis/corneal abrasion: The insect impact likely caused direct mechanical trauma to the conjunctiva and potentially the corneal epithelium
• Scleral redness (conjunctival hyperemia) is the inflammatory response to trauma
• Eye pain indicates either corneal epithelial disruption or conjunctival inflammation

Critical Differential to Rule Out

You must examine for:

• Retained foreign body (insect parts, stinger): Use slit-lamp examination and evert the eyelids 1
• Corneal abrasion: Perform fluorescein staining to identify epithelial defects 1
• Penetrating injury: Assess for scleral defects, especially if pain is severe 2
• Secondary infection: Look for infiltrates, purulent discharge, or progressive symptoms 1

Immediate Treatment Protocol

1. Antibiotic Prophylaxis (Essential)

A broad-spectrum topical antibiotic is recommended for any patient presenting with corneal abrasion following trauma 1. This prevents both bacterial and fungal infection.

• First-line: Fluoroquinolone eye drops (moxifloxacin 0.5% or similar) 4 times daily for 5-7 days 3
• Start within 24 hours of injury to prevent ulceration 1

2. Symptomatic Management

• Cold compresses to reduce pain and swelling 4
• Oral analgesics (NSAIDs or acetaminophen) for pain control 4
• Oral antihistamines (cetirizine 10 mg daily) if significant allergic/inflammatory component 3

3. What NOT to Do

• Do NOT patch the eye - increases risk of secondary bacterial keratitis 1
• Do NOT use therapeutic contact lens in trauma cases - same infection risk 1
• Avoid topical corticosteroids initially until infection is ruled out 5

Follow-Up Requirements

Red Flags Requiring Urgent Ophthalmology Referral

• Visual disturbance or decreased vision 6
• Moderate to severe pain (suggests deeper involvement) 6
• Photophobia (suggests corneal or intraocular involvement) 6
• Worsening symptoms after 24-48 hours (suggests infection) 1
• Purulent discharge or infiltrate (bacterial keratitis) 1

Expected Clinical Course

• Mild traumatic conjunctivitis should improve within 24-48 hours
• Complete resolution typically occurs within 5-7 days
• If symptoms persist beyond 48 hours or worsen, consider:
  • Retained foreign body 3
  • Secondary bacterial keratitis 1
  • Deeper penetrating injury 2

Special Considerations for Insect-Related Trauma

While rare, insect stings to the eye can cause severe complications 3, 7, 2:

• Bee/wasp stingers can penetrate the cornea and cause severe inflammation 3
• Toxic reactions from venom can mimic infection 7
• Secondary endophthalmitis is possible with penetrating injuries 2

If the insect was a bee or wasp AND there is severe pain, significant vision loss, or signs of intraocular inflammation, immediate ophthalmology consultation is mandatory 3, 7, 2.

Patient Education

Instruct the patient to return immediately if:

• Vision decreases
• Pain worsens or becomes severe
• Discharge becomes purulent
• Symptoms don't improve within 48 hours
• New symptoms develop (photophobia, severe headache)

The combination of prophylactic antibiotics and close monitoring prevents the most serious complication—bacterial keratitis—while allowing most simple traumatic injuries to heal without intervention 1.