What is the differential diagnosis for a patient with a 2-week history of decreased visual acuity, floaters, and metamorphopsia (distortion in visual field) in one eye?

Differential Diagnosis for Unilateral Visual Changes with Floaters and Metamorphopsia

This patient requires urgent ophthalmologic evaluation within 24 hours due to high-risk features suggesting possible retinal pathology, particularly retinal tear, posterior vitreous detachment with complications, or vitreomacular traction.

Primary Differential Diagnoses

High-Risk Conditions Requiring Urgent Assessment

Retinal Tear or Detachment

• The combination of new floaters with visual acuity changes carries a 14-23% risk of retinal tear, even without flashes 1, 2
• Subjective visual reduction (which this patient has) increases the likelihood of retinal tear significantly (likelihood ratio 5.0-7.9) 3, 2
• Metamorphopsia (objects appearing "skinner"/distorted) can indicate macular involvement or impending detachment 4
• Between 8-22% of patients with acute posterior vitreous detachment symptoms have a retinal tear at initial examination 4, 2

Posterior Vitreous Detachment (PVD) with Complications

• PVD is the most common cause of acute-onset floaters 1, 2
• Even uncomplicated PVD carries a 2-5% risk of developing retinal breaks within the following 6 weeks 4, 2
• The 2-week duration places this patient in the high-risk window for delayed tear formation 4

Vitreomacular Traction (VMT)

• VMT causes decreased visual acuity, metamorphopsia, and floaters—matching this patient's presentation 5
• The distortion ("objects seem skinner") is characteristic of tractional forces on the macula 5
• VMT occurs when partially separated vitreous remains adherent to the macula, creating traction 5

Moderate-Risk Macular Pathology

Epiretinal Membrane (ERM)

• ERMs cause decreased visual acuity, metamorphopsia, and difficulty using both eyes together 5
• The visual distortion pattern fits with ERM-induced macular traction 5
• ERMs can develop following PVD and may present with similar symptoms 5

Macular Hole

• Can present with metamorphopsia and decreased visual acuity 5
• May be associated with VMT or develop as a complication of vitreous traction 5
• The 2-week timeframe is consistent with progressive macular hole formation 5

Other Considerations

Vitreous Hemorrhage

• Often presents as sudden increase in floaters (described as "shower" or "smoke") 4
• Strongly associated with retinal tears (likelihood ratio 10) 2
• Direct correlation exists between hemorrhage amount and likelihood of retinal tear 4

Critical Red Flags Present in This Case

This patient has THREE high-risk features:

• Subjective visual acuity reduction (LR 5.0-7.9 for retinal tear) 3, 2
• New-onset floaters of 2-week duration (14-23% tear risk) 1, 2
• Metamorphopsia indicating macular involvement 6, 3

Immediate Management Algorithm

Step 1: Urgent Ophthalmology Referral (Same Day)

• Patient requires examination by an ophthalmologist skilled in binocular indirect ophthalmoscopy with scleral depression 4
• If peripheral retina cannot be adequately visualized, B-scan ultrasonography is mandatory 4, 7

Step 2: Key Examination Components Needed

• Visual acuity measurement in each eye separately 4, 2
• Slit-lamp biomicroscopy looking for vitreous pigment (Shafer's sign) or hemorrhage 4, 2
• Dilated fundus examination with peripheral retinal assessment 4
• Optical coherence tomography (OCT) to evaluate for VMT, ERM, or macular hole 5

Step 3: Risk Stratification

• Vitreous pigment absence has negative likelihood ratio of 0.23 for retinal tear 2
• Vitreous hemorrhage presence has positive likelihood ratio of 10 for retinal tear 2
• Any vitreous pigment, hemorrhage, or visible vitreoretinal traction mandates follow-up within 6 weeks even if initial exam is negative 4, 7

Common Pitfalls to Avoid

Do not assume floaters are benign without proper ophthalmologic examination - retinal tears can develop up to 6 weeks after initial PVD symptoms 4, 2

Do not delay referral based on absence of flashes - patients with floaters alone still have 14-23% risk of retinal tear 1

Do not underestimate metamorphopsia - this symptom indicates macular pathology requiring urgent assessment 6, 3

Do not provide false reassurance - even if initial examination is normal, 2-5% will develop breaks in subsequent weeks 4, 2

Follow-Up Requirements

If initial examination reveals no retinal breaks, the patient still requires re-examination within 6 weeks, as approximately 80% of patients who later develop breaks had either pigmented cells, hemorrhage, or new symptoms 4

The patient must be instructed to return immediately for any increase in floaters, loss of visual field, or further decrease in visual acuity 5, 4