Diagnostic Testing for Lash-Related Issues
For lash-related problems, microscopic evaluation of epilated eyelashes is the primary diagnostic test, performed by placing plucked lashes on a glass slide with fluorescein under a coverslip to detect Demodex mites, which are a common cause of persistent blepharitis with lash collarettes. 1
Clinical Examination of Lashes
The external examination should specifically evaluate for:
- Loss, breakage, or misdirection of eyelashes - key indicators of chronic eyelid inflammation 1
- Abnormal deposits/sleeves at the base of the eyelashes (collarettes) - pathognomonic for Demodex infestation 1, 2
- Vascularization or hyperemia of eyelid margins - suggests active inflammation 1
- Ulceration, vesicles, or scaling at the lash line 1
Microscopic Lash Evaluation
When lash collarettes are present with persistent blepharitis, microscopic evaluation for Demodex mites should be performed. 1 The technique involves:
- Epilating (plucking) several eyelashes from affected areas 1
- Placing the lashes on a glass slide 1
- Adding a drop of fluorescein 1
- Applying a coverslip 1
- Examining with slit lamp and 90 Diopter condensing lens 1
The severity of ocular surface discomfort correlates strongly with the number of Demodex mites per eyelash. 2
Microbiologic Testing
Cultures of the eyelid margins are indicated for patients with recurrent anterior blepharitis with severe inflammation or those not responding to therapy. 1, 3 This is not routinely performed but becomes essential when:
- Standard treatment fails 1
- Severe inflammation is present 1
- Recurrent episodes occur despite appropriate therapy 1
Red Flag Situations Requiring Biopsy
Eyelid biopsy is indicated when chronic blepharitis is unresponsive to therapy, especially with unilateral involvement, to exclude carcinoma. 1, 3 Specific indications include:
- Marked asymmetry between eyes 1
- Resistance to standard therapy 1
- Unifocal recurrent chalazia that don't respond to treatment 1
- Focal lash loss (ciliary madarosis) 1
- Loss of normal eyelid margin anatomy 1
Before obtaining biopsy for suspected sebaceous carcinoma, consultation with a pathologist is recommended to discuss frozen sections and conjunctival mapping for pagetoid spread, with fresh tissue needed for special lipid stains like oil red-O. 1
Risk Factor Assessment
Important historical factors that increase risk of lash-related problems include:
- Advancing age - positive correlation with Demodex infestation 2
- Isotretinoin use - associated with increased bacterial colonization and blepharitis 2, 3
- Dupilumab therapy - causes conjunctivitis, keratitis, and blepharitis in 32-55% of patients 2, 3
- Eyelash extensions - can cause keratoconjunctivitis and allergic blepharitis from formaldehyde-containing glues 4
- Dry eye disease and meibomian gland dysfunction - frequently associated with Demodex 2
Common Pitfalls
Children have much lower rates of Demodex infestation (only 12%), so other etiologies should be prioritized in pediatric patients with lash problems. 2 However, pediatric blepharokeratoconjunctivitis is often unrecognized and can be severe, potentially leading to amblyopia. 3
Carcinoma can masquerade as chronic blepharitis, particularly with unilateral involvement - maintain high suspicion and low threshold for biopsy in treatment-resistant cases. 1, 3