Speaker - Stefano Barabino

The lacrimal glands and the corneal and conjunctival epithelial cells maintain a delicate balance essential for ocular health. Disruptions to this balance, often resulting from various factors, lead to dry eye syndrome, complicating recovery. Key contributors to dry eye include environmental factors such as low humidity and temperature fluctuations. Poor sleep patterns correlate with dry eye, although the precise relationship remains unclear. Contact lenses and glaucoma treatments, particularly those containing benzalkonium chloride, exacerbate the risk. Genetics likely plays a significant role, though its exact impact is poorly understood. Individuals with autoimmune diseases are more susceptible to dry eye, but even those without genetic or autoimmune predispositions can develop the condition. As tear break-up time and production decrease, aging is a major factor, increasing dry eye incidence in older adults, especially those undergoing cataract surgery, where pre-existing dry eyes can influence surgical outcomes. 

Pathogenesis, ocular surface homeostasis, and chronic inflammation involve complex processes. Recent research introduces the concept of "para-inflammation," a beneficial inflammatory response to restore ocular surface balance. However, dysfunctional para-inflammation can lead to chronic inflammation. Although the exact mechanisms remain unclear, macrophages are known to be involved. Activated macrophages in the cornea and conjunctiva can shift para-inflammation from functional to dysfunctional. Antigen-presenting cells also contribute to this process. Dry eye is a significant concern for ophthalmologists and greatly affects patients' quality of life, often leading to anxiety and depression due to limited treatment options. Many patients receive unclear diagnoses despite consulting multiple specialists, resulting in frustration. Misinterpreting symptoms, such as attributing them to conjunctivitis, further complicates the diagnosis. Effective diagnosis involves directly observing the ocular surface and considering patient symptoms, which often provide clues about onset and triggers, such as air conditioning or wind exposure. Specific complaints, such as relief when closing the eyes, can indicate dry eyes. Patients with blepharitis generally report worse symptoms in the morning, whereas those with aqueous-deficient dry eye experience more discomfort in the evening. Diagnostic procedures include staining the ocular surface with fluorescein and lissamine green, which helps differentiate dry eye from other ocular surface diseases, ensuring accurate diagnosis.

Accurate diagnosis of dry eye involves distinguishing between different degrees and types of the condition. The term "dry eye" encompasses a range of symptoms from mild to severe yet is often used uniformly. For example, a patient experiencing dryness from prolonged screen use may receive the same diagnosis as someone with severe, chronic dry eye due to an autoimmune disease despite significant underlying causes and severity differences. Efforts to classify dry eye into distinct types have led to the following categorization: Type 1 includes patients with sporadic or intermittent symptoms, often subclinical inflammation; Type 2 involves more frequent symptoms with clear ocular surface alterations and immune activation, requiring artificial tears and anti-inflammatory treatments; Type 3 represents chronic conditions with T cell activation and persistent inflammation, where full recovery is unlikely, though treatments may improve the clinical picture. 

Fluorescein staining is crucial for diagnosing and assessing the severity of dry eye disease. It reveals tiny dots in the cornea, which may indicate toxicity rather than dry eye. The staining pattern, consisting of small dots or larger areas, provides insight into the underlying cause. Fluorescein also assesses tear break-up time (TBUT), with different TBUT patterns suggesting varying pathogenesis. TBUT is indicative of whether the tear film effectively protects the ocular surface. Sometimes, a thin tear film may not be the issue; conditions like conjunctivochalasis must be addressed. Severe dry eye with significant staining points to immune involvement, with staining patterns indicating antigen-presenting cell activation and chronic inflammation. Patients with extensive staining are categorized as Type 3 dry eye, requiring targeted treatment for chronic disease management. 

Lissamine green staining is essential for detecting ocular surface damage, particularly in the conjunctiva. Liquid formulations of lissamine green in Italy in single-dose formats offer precise application and better visualization than traditional strips. Applying 10 microliters of the liquid with a dispenser allows clear conjunctiva staining. When used with a red filter on the slit lamp, the green stain appears black, enhancing damage visibility. Lissamine green staining correlates with ocular surface inflammation, with markers like interleukin 6 (IL-6), interferon-gamma, IL-17, and matrix metallopeptidase (MMP-9) indicating inflammation. While it does not quantify inflammation like flow cytometry, it provides a practical method for gauging inflammation levels and monitoring anti-inflammatory treatment efficacy. Lissamine green also aids in diagnosing conditions often mistaken for dry eye, such as superior limbic keratoconjunctivitis and lid wiper epitheliopathy. Superior limbic keratoconjunctivitis, affecting the superior part of the bulbar conjunctiva, is more evident with lissamine green staining. Lid wiper epitheliopathy, frequently underdiagnosed, is better identified with lissamine green than fluorescein due to background staining issues.

In conclusion, diagnosing dry eye requires a systematic approach. By attentively listening to patients' symptoms, evaluating the ocular surface during slit lamp examination, and utilizing diagnostic tools like fluorescein and lissamine green staining, effective assessment and differentiation of ocular surface conditions are achieved. These tools facilitate visualization of damage, evaluation of inflammation, and guidance for treatment, leading to more accurate diagnoses beyond the generic term "dry eye." 

42nd Congress of the European Society of Cataract and Refractive Surgeons, 6 – 10 September 2024, Fira de Barcelona, Spain.