We are often confronted with middle-aged and elderly women or young people who complain of dry eyes, but your initial examination does not reveal any obvious ocular pathology, how should you treat them? How do you explain why the patient has frequent tearing and feels dry eyes? Do these people have dry eyes? Is it dry eye, dry eye disease or dry eye syndrome? How to differentiate? The following is a brief description of the basis, definition, clinical manifestations, classification, diagnosis, and treatment of dry eye to illustrate these questions.
Tear film: The eyeball runs freely under the lid and looks “watery and bright” because the conjunctiva and cornea (i.e., the surface of the eye) on the front surface of the eye are covered with a tear film. The tear film not only provides lubrication for the opening and closing of the eyelids, but also makes the irregularities of the ocular surface into a smooth optical interface to improve the quality of vision, and the secondary tear fluid also has an antibacterial effect.
The tear film is the protective layer of the cornea on the ocular surface and has 2 layers: a lipid layer on the surface and an aqueous layer in the deeper layers.
The lipid layer of the tear film is a lid gland secretion, very thin (0.1 μm), whose main function is to prevent evaporation of tears. The lacrimal gland secretes the components of the aqueous layer that provides tears, secreting an aqueous solution containing proteins, small molecules and electrolytes. The main protein components are proteins with antibacterial activity (such as lactoferrin and lysozyme) and immunoglobulin A. The aqueous layer of tears has mainly a cleansing and lubricating effect. The mucus layer is secreted by conjunctival cupped cells, and mucus stabilizes the aqueous layer by providing a hydrophilic contact surface. Tear secretion is under psychoneuroendocrine control with a basal tear secretion of 1.2 μl/min, but a variety of stimuli can induce the production of large amounts of tears. The distribution of tears is spread throughout the ocular surface by transients, and transient actions depend on the integrity of the transient reflex arc, including normal corneal perception, eyelid anatomy, and innervation of the trigeminal and facial nerves. Different types of dry eye manifest when both layers of the tear film structure are qualitatively and quantitatively altered for various reasons.
Definition of dry eye: A group of diseases in which the tear film becomes unstable due to a decrease in tear volume and quality abnormalities for various reasons, causing a series of symptoms and ocular surface damage, are collectively referred to as dry eye. In clinical work, it is often referred to as dry eye when there are symptoms of dry eye but no signs of ocular surface damage. Those with symptoms and signs of dry eye are called dry eye disease. Dry eye syndrome, on the other hand, is an ocular change of dry syndrome (Sjogren’s syndrome), which is a kind of dry eye disease. Dry eye syndrome and dry eye disease are collectively called dry eye.
Clinical manifestations: The signs and symptoms of dry eye often include dryness, burning, foreign body sensation, itching, photophobia, blurred vision, fluctuating visual acuity, and eye redness in both eyes or one eye. Dry eye often has a non-infectious, immune-related inflammatory response to the ocular surface, which is a common pathogenesis and clinical manifestation of all types of dry eye.
Classification: Dry eye can be divided into two main categories, namely, reduced lacrimal gland secretion and normal lacrimal gland secretion with rapid evaporation. Domestic scholars have classified dry eye into five categories according to changes in the structural composition of the three layers of tears and the etiology: 1.
1, aqueous deficiency type dry eye.
The aqueous component of the tear film is reduced or insufficient, and many systemic factors cause this type of dry eye. Such as Sjogren’s syndrome, drug side effects (and beta-blockers, anticholinergics, antihistamines, etc.), hormonal disorders (such as female menopause), inflammation of the lacrimal gland, trauma, surgery, tumors. Old age, mental stress, decreased resistance, lack of sleep also cause.
2.Lipid abnormal dry eye (including evaporation over-strong dry eye).
It is caused by abnormalities in the quality and quantity of the lipid layer of the tear film, including incomplete lipid layer (such as lid gland dysfunction, blepharitis), reduced blinking (such as computer operation, fine work, driving, etc.), and changes in the environment (such as hot and dry climate, air conditioning, heavily polluted air, preoptic surgery, and eyelid defects). This type of dry eye often increases the secretion of aqueous tears due to inflammatory stimulation.
3. Mucin deficient dry eye.
Conjunctival cupped cells or corneal epithelial cells when inflammation or injury occurs (such as surgical trauma, ocular surface chemical burns, thermal burns, vitamin A deficiency, preservatives in eye drops) cause a lack of mucus layer leading to tear film instability causing dry eye.
4, abnormal tear dynamics type dry eye.
Including transient abnormalities (such as lid paralysis, lid ectropion), delayed tear drainage (tear dots, narrow tear ducts destroy tear self-cleaning drainage, pollution tear retention), conjunctival laxity, etc.
5.Mixed dry eye.
Dry eye caused by two or more of the above causes.
Diagnosis: Self-complained symptoms such as dry eyes, foreign body sensation and visual fatigue, especially in the elderly, middle-aged and older women, and workers in computer-operated occupations, are the first to suspect dry eye disease. The commonly used diagnostic tests are based on criteria: tear stability (BUT), tear secretion (schirmerTest) and ocular surface damage (fluorescein staining).
Diagnostic process.
Suspected case => examination of membrane breakage time (exclude tear film related disease if normal) => shortened => sexual tear secretion examination (schirmer test) => reduced: systemic disease examination (dry syndrome); => normal: eyelid and lid margin examination => lid gland dysfunction (evaporative overactive dry eye).
Treatment principles.
Etiological treatment + relief of dry eye symptoms.
Treatment methods.
1.First treat the primary cause of dry eye.
2.Non-pharmacological treatment.
Ocular physiotherapy: Physiotherapy is implemented daily for patients with lid gland dysfunction. First, apply a hot compress to the eyelids for 5-10 minutes, followed by a rotational massage of the eyelids, and finally, scrub the eyelids with a cotton swab dipped in non-irritating baby shampoo and apply antibiotic eye ointment.
Removal of pathogenic factors: increase the frequency of transient eyes when operating a computer, take regular breaks, and place the display below the eye level to reduce tear evaporation. Reduce or change airflow when working in air-conditioned rooms to increase indoor humidity.
3.Medication.
Artificial tears: the drug of choice for the treatment of dry eyes. Long-term or frequent users should consider the physicochemical properties of artificial tears and the effect of preservatives on the ocular surface.
Topical anti-inflammatory/immunosuppressant: glucocorticoids or non-steroidal hormone anti-inflammatory drugs are used in patients with moderate to severe dry eye. The immunosuppressant cyclosporine is also routinely preferred as an anti-inflammatory agent.
Androgens: Used to treat dry syndrome and evaporative overactive dry eye, elevate androgen levels and regulate body and local immune function.
4.Surgical treatment
Tear punctal obstruction, lacrimal duct blocking or partial lid margin suturing is performed in patients with severe dry eye with significantly reduced lacrimal secretion.