AAOpt 2026: Demodex tied to worse MGD as dry eye questionnaires miss blepharitis

Standard dry eye questionnaires capture only 22.4% of Demodex blepharitis symptoms, according to a targeted literature review presented at the American Academy of Optometry Annual Meeting, held in Anaheim, California.¹ A separate systematic review linked Demodex infestation to worse meibomian gland structure and function across 22 studies.² A third poster found neither perfluorohexyloctane (PFHO; Miebo; Bausch + Lomb) nor Systane Pro artificial tears (Alcon) clearly changed meibomian gland scores after 1 month.³

The posters bear directly on the lid margin workup in patients with meibomian gland dysfunction (MGD). Authors of both reviews called on clinicians to evaluate Demodex directly rather than rely on symptom scores.^1,2

Why do dry eye questionnaires miss Demodex blepharitis?

Walter Whitley, OD, MBA, FAAO, and colleagues paired a targeted literature review with social media listening on platforms including Reddit and TikTok to build a patient-centered conceptual model of Demodex blepharitis.¹ They identified 23 symptoms, most commonly watery eyes, itching, burning or stinging, redness, dryness, foreign body sensation, eyelash loss, and crusting. The team then screened 63 ocular patient-reported outcome measures, none specific to Demodex blepharitis.

Six dry eye instruments advanced to concept mapping, including the Dry Eye Questionnaire 5-item (DEQ-5), the Ocular Surface Disease Index (OSDI), and the Standardized Patient Evaluation of Eye Dryness (SPEED).¹ On average, 72.8% of symptoms in these tools were relevant to Demodex blepharitis. Although, the instruments captured only 22.4% of Demodex blepharitis symptoms, which the authors concluded reflects poor content validity and may contribute to missed or incorrect diagnoses.

Demodex infestation and meibomian gland dysfunction outcomes

Bridgitte Shen Lee, OD, FAAO, and colleagues searched PubMed and Embase through January 6, 2026, for studies reporting MGD outcomes stratified by Demodex status, excluding interventional studies.² One investigator extracted data, and a second verified it independently. Across 22 included studies, MGD prevalence ranged from 44% to 99% in patients with Demodex infestation, while Demodex prevalence ranged from 45% to 89% in patients with MGD.

Compared with patients without infestation, patients with Demodex had worse gland expressibility in 3 of 6 studies, poorer meibum quality in 6 of 8, and greater gland dropout and atrophy in 5 of 7. Lid margin abnormality scores were higher in 3 of 4 studies. Tear breakup time (TBUT) was shorter in all 4 studies reporting it, and corneal fluorescein staining was higher in both studies reporting it.²

Perfluorohexyloctane vs Systane Pro for meibomian gland function

In a randomized, double-masked, multisite trial, Andrew Pucker, OD, PhD, and colleagues compared PFHO with Systane Pro, each dosed 4 times daily for 1 month.³ Eligible adults had OSDI scores of 23 to 50, TBUT of 5 seconds or less, and Schirmer I scores of at least 5 mm in both eyes, selecting for evaporative dry eye. Investigators graded the central eight upper and central 5 lower eyelid glands on a novel Meibomian Gland Composite Score, with lower scores indicating better function.

Right-eye TBUT rose from 3.65 to 5.33 seconds in the PFHO group (n = 86) and from 3.66 to 5.02 seconds in the Systane Pro group (n = 68). The authors reported numerical improvement with both drops, with no numerical difference between groups at 1 month. Neither drop had a clear effect on gland composite scores.

For optometrists, the 2 reviews point in the same direction: dry eye questionnaires are not reliable screens for Demodex blepharitis, and patients with MGD warrant direct lid margin and lash evaluation.^1,2 The Pucker trial suggests 1 month of either drop may improve tear stability without changing gland function, although the study was short and did not assess other MGD therapies.³

References

1. Whitley W, Theriot P, Karpecki PM, et al. Assessment of dry eye questionnaires for Demodex blepharitis: evidence from a targeted literature review. Poster presented at: Academy 2026 Anaheim; October 1, 2026; Anaheim, CA.

2. Shen Lee B, Koetting C, Li O, et al. Associations between Demodex infestation and meibomian gland structure and function: a systematic review. Poster presented at: Academy 2026 Anaheim; October 1, 2026; Anaheim, CA.

3. Pucker AD, Wirta D, Lievens CW, et al. Assessing meibomian gland function in dry eye subjects treated with PFHO or Systane Pro. Poster presented at: Academy 2026 Anaheim; October 1, 2026; Anaheim, CA.