How to Diagnose a Scratch on the Sclera
To diagnose a scratch on the sclera, use fluorescein staining with a slit-lamp biomicroscopic examination, which will reveal the scratch as a bright green area against the white scleral background. This is the most effective method for visualizing superficial scleral injuries.
Examination Approach
Initial Visual Assessment
- Examine under good lighting conditions
- Look for localized redness, vessel dilation, or subtle discoloration
- Check for any visible disruption to the smooth white surface of the sclera
Slit-Lamp Biomicroscopy (Essential)
- Use various illumination techniques:
- Direct illumination to assess surface irregularities
- Sclerotic scatter to highlight surface abnormalities
- Specular reflection to detect subtle surface changes 1
- Carefully examine:
- Conjunctiva for injection and inflammation
- Sclera for any visible abrasions, ulcerations, or foreign bodies
- Adjacent cornea for associated injuries 1
Vital Dye Staining
- Apply fluorescein dye to the ocular surface
- Observe with cobalt blue filter on the slit lamp
- Scleral scratches will appear as bright green areas where the dye pools in the defect
- Document the size, shape, and location of any staining 1
Additional Diagnostic Considerations
History Elements to Assess
- Mechanism of potential injury (foreign body, trauma, contact lens use)
- Onset and duration of symptoms
- Associated symptoms (pain, redness, tearing, photophobia)
- Previous ocular conditions or surgeries 1
Physical Findings
- Look for:
- Foreign bodies under the eyelids
- Eyelid swelling or abnormalities
- Conjunctival injection (redness)
- Tear film abnormalities
- Anterior chamber reaction (cells and flare) 1
Differential Diagnosis
Consider other conditions that may mimic scleral scratches:
- Episcleritis
- Scleritis (especially posterior scleritis which can present with eye pain and redness) 2
- Subconjunctival hemorrhage
- Conjunctivitis
- Foreign body 1
Common Pitfalls to Avoid
- Failing to evert the eyelids to check for hidden foreign bodies
- Missing deeper scleral involvement that might indicate more serious pathology
- Overlooking associated corneal injuries
- Confusing conjunctival hemorrhage with scleral injury
- Not using adequate magnification to visualize subtle scratches 1
When to Consider Additional Testing
- If the injury appears deep or extensive
- When there's significant pain disproportionate to visible findings
- If there's no improvement with initial treatment
- When there's suspicion of infection or foreign body 2, 3
Remember that while superficial scleral scratches may heal well, deeper injuries require careful monitoring as they can lead to more serious complications including infection or thinning of the sclera 4.