Evaporative Dry Eye

Evaporative dry eye results from an unstable lipid layer allowing excessive tear evaporation, with normal lacrimal gland secretion. It is the commonest form of dry eye (about 85 percent of cases).

• Main cause: meibomian gland dysfunction (obstruction, reduced and abnormal meibum).
• Other causes: blepharitis, Demodex infestation, reduced or incomplete blinking (screen use, Parkinson disease, facial palsy), lid malposition and lagophthalmos, vitamin A deficiency, contact lens wear, topical preservatives, isotretinoin, allergic eye disease, and low humidity.

• Burning, grittiness, watering, fluctuating vision, symptoms worse on prolonged screen use or reading and on waking.
• Lid margin changes: telangiectasia, plugged gland orifices, expressed turbid or toothpaste like meibum, lid margin thickening, notching, madarosis, collarettes (Demodex).
• Foamy tear film, reduced tear break up time, inferior punctate keratopathy.
• Chalazia and recurrent hordeola.
• Rosacea is common (facial erythema, telangiectasia, papules).

• Lid margin and meibomian gland expression under slit lamp: quality (clear, cloudy, granular, toothpaste) and expressibility graded.
• Tear break up time under 10 seconds with normal Schirmer result (over 10 mm in 5 minutes).
• Meibography (infrared imaging) showing gland dropout or shortening; tear film lipid layer thickness interferometry.
• Tear osmolarity, corneal and conjunctival staining.
• Blink assessment (partial blinks) and lid closure check.
• Epilation of lashes for Demodex microscopy (more than 3 mites per lash).

• Warm compresses 8 to 10 minutes, once or twice daily, with lid massage and lid hygiene (hypochlorous acid 0.01 percent spray or diluted baby shampoo or commercial lid wipes).
• Lubrication with lipid containing drops (liposomal sprays, emulsions) 4 to 6 times daily.
• Oral doxycycline 100 mg once or twice daily for 1 to 2 weeks then 50 to 100 mg daily for 3 months, or azithromycin 500 mg daily for 3 days, repeated at 7-day intervals for 3 cycles (or 250 mg daily for 4 weeks). Avoid in pregnancy, breastfeeding and children under 8 (use azithromycin).
• Topical azithromycin 1 percent twice daily for 3 days then once daily for 4 weeks.
• Demodex: tea tree oil 50 percent in office lid scrub and 5 percent tea tree wipes daily, or lotilaner 0.25 percent twice daily for 6 weeks.
• Thermal pulsation (LipiFlow) or intense pulsed light 3 to 4 sessions at 3 to 4 week intervals, and in office expression or probing for obstructed glands.
• Short course topical steroid (loteprednol 0.5 percent twice daily for 2 weeks) for inflammation, and cyclosporine 0.05 percent twice daily.
• Dietary omega-3 supplementation (EPA and DHA 2 g daily), treat rosacea, correct lid malposition, blink exercises and screen ergonomics.