Detecting Demodex Blepharitis during preop cataract surgical visit

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EP: 1.Detecting Demodex Blepharitis during preop cataract surgical visit

EP: 2.Preop Visually Significant OSD: Treatment Strategy and Outcomes

EP: 3.Demodex Blepharitis in a Contact Lens Wearer

EP: 4.Demodex Blepharitis in a Contact Lens Wearer: Treatment Plan and Outcomes

Preoperative Cataract Patient with Visually Significant Ocular Surface Disease

The diagnostic approach to ocular surface disease (OSD) in preoperative cataract patients involves careful correlation between symptoms and clinical signs. In a case-based analysis of a 74-year-old female presenting for preoperative cataract evaluation with baseline poor vision, diurnal fluctuations, and chronic ocular pruritus, pathognomonic signs of Demodex blepharitis were identified. The patient exhibited characteristic eyelash scratching behavior (rubbing fingernails along eyelash margins), lid margin erythema, morning crusting, and cylindrical collarettes at the base of eyelashes. Despite a previous diagnosis of allergic conjunctivitis, targeted questioning about the quality and localization of pruritus revealed lid margin-specific symptoms, prompting deeper examination for Demodex infestation. This diagnostic pearl—distinguishing between knuckle-digging (allergy), generalized surface discomfort (dry eye), and lash margin-specific irritation (Demodex)—represents a valuable clinical differentiation tool.

Comprehensive preoperative OSD evaluation, following the ASCRS preoperative OSD algorithm (published in JCRS, 2019), revealed multifactorial pathology. Initial topographic examination demonstrated an "irregularly irregular" corneal surface pattern—described as the "atrial fibrillation of the ocular surface"—which created inconsistent astigmatic measurements between different keratometric devices. The patient scored 22/28 on the SPEED questionnaire and exhibited 12/18 risk factor indicators. Point-of-care diagnostics showed hyperosmolarity (312/331 mOsm/L OD/OS), indicating moderate-to-advanced dry eye disease, and positive MMP-9 testing, confirming significant ocular surface inflammation. The "Look, Lift, Pull, Push" (LLPP) examination technique revealed substantial collarettes at the eyelash bases, reduced tear meniscus height, and significant corneal epithelial disruption. Meibomian gland expression demonstrated thick, inspissated meibum with poor expressibility.

This constellation of findings constituted "visually significant ocular surface disease," necessitating surgical postponement and targeted treatment. The evidence-based approach to Demodex management is particularly critical in preoperative patients, as studies reveal higher loads of gram-positive bacteria (including Staphylococcus, Streptococcus, and MRSA) in the presence of Demodex, potentially increasing endophthalmitis risk. The TITAN study documented Demodex blepharitis in 56% of preoperative cataract patients, underscoring the prevalence of this condition. Despite this high prevalence, the majority of these patients remain asymptomatic—research from multiple institutions confirms that 77% of preoperative cataract patients exhibit abnormal corneal staining, while only 13% report symptoms, suggesting neurotropism or symptom underreporting due to visual prioritization of cataract symptoms.