☆ What is dry eye disease?
Tears are the basic guarantee for eye moisturization and clear vision. However, if the tear film becomes unstable due to abnormal tear quality and quantity or kinetics caused by various reasons, resulting in ocular surface tissue lesions, it can lead to dryness and other uncomfortable symptoms in the eye, and this ocular surface disease is dry eye.
Dong Nuo, Ocular Surface and Corneal Diseases, Xiamen Eye Center, Xiamen University
Dry eye is one of the most common reasons for people to seek medical attention, and the prevalence of the disease is about 2-3 times higher in women than in men. In the United States, approximately 6 million women and 3 million men have moderate to severe dry eye symptoms.
In most cases, patients with dry eye have unstable vision and have difficulty concentrating on tasks such as reading and driving.
☆ The role of natural tears
The composition of tears is 98.2% water and 1.8% solid, which is weakly alkaline. In addition to proteins and inorganic salts, the solid also contains cell growth factors such as lactoferrin, lysozyme, lactoperoxidase, epidermal growth factor, endothelin-1, and alkaline fibroblast growth factor. Proteins reduce the surface tension of tears, and salts maintain a certain osmotic pressure so that tears can be evenly distributed on the surface of the eye, forming a transparent and smooth protective film.
Clinically, the cornea is often compared to a plant, the surface of the eye to soil, and tears to rain, and plants cannot grow without fertile soil and abundant rain. The human eye is no different. The cornea is lubricated primarily by tears secreted by the lacrimal glands in the upper eyelids, and naturally secreted tears not only moisten the eye, making it cool, comfortable, and bright, but also protect the eye and eyelids from damage and infection.
The tear river is the tear fluid that accumulates between the lower eyelid and the surface of the eye, and its height can reflect the amount of tears, the function of the tear system and pathological changes, and is the gold standard for monitoring the severity of dry eye.
☆ The developmental course of dry eye disease
The progression of dry eye disease is a natural history of chronic progression, and you need to work with your physician to establish an objective expectation for effective treatment. In most cases, dry eye does not impair vision, but mainly causes irritation and fluctuations in vision. In some patients, there are factors that exacerbate the condition, such as decreased tear production due to systemic medication or increased tear evaporation due to environmental factors, making the symptoms rapidly worse, and their elimination often results in significant relief or even complete disappearance. In those patients with an irreversible decrease in tear production or excessive tear evaporation due to chronic pathology such as blepharitis, the disease can have a chronic course with symptoms that are mild and severe, eventually progressing over time to moderate to severe dry eye.
In patients with moderate and severe dry eye, reversible conjunctival squamous metaplasia or conjunctival corneal punctate erosion may develop. Very few patients with severe dry eye may develop complications such as ocular surface keratosis, corneal ulceration, corneal scarring, corneal thinning or neovascularization, resulting in severe vision loss.
☆ Which groups are more likely to suffer from dry eye disease?
1. In recent years, the trend of dry eye disease is younger, mainly due to modern life, young people’s work and entertainment and television, computer contact more and more, long hours facing the fluorescent screen, excessive reading, lack of normal blinking, and blinking can make tears better wet eyes. More than 90% of people who work more than 3 hours a day in front of a computer have problems with their eyes.
2. Environmental factors such as airplane travel, reduced air humidity, use of air conditioning, smoke (smoking), ultraviolet light, air pollution and high temperatures can increase tear evaporation and lead to dry eyes.
3. Driving at night increases lid exposure, decreases transient frequency, and increases tear evaporation causing dry eye symptoms in subclinical dry eye patients.
4. Contact lens wear, arrangement and care. Contact lenses are floating on tears, and wearing them accelerates tear evaporation. The discomfort and poor tolerance of contact lens wear is mainly caused by dry eye, especially soft contact lenses can quickly evaporate tears, creating a foreign body sensation and precipitating proteins on the lenses. On the other hand, dry eye can make the contact lens wearer’s cornea less resistant to damage, making contact lenses more likely to scratch the cornea.
5. 75% of people over the age of 65 suffer from dry eye. This is because tear production decreases as people get older. By the age of 65, tear production by the lacrimal glands is only 40% of what it was at age 18. Reduced secretion can also cause eye irritation, sometimes resulting in a reflex tearing response, or tear spillage.
6. Menopause, pregnancy, lactation, and women taking oral contraceptives can produce dry eye symptoms due to changes in hormone levels.
7. Certain diseases
Abnormal eyelid position, incomplete eyelid closure, blepharitis, and neuromuscular diseases affecting transient vision (e.g., Parkinson’s disease, Bell’s palsy) are closely related to dry eye disease. The incidence of allergic eye disease has been increasing in recent years, and allergens can aggravate the symptoms of dry eye and lead to worsening of dry eye.
Dry eye can occur in patients with systemic viral infections, and patients with acquired immunodeficiency syndrome (AIDS), hepatitis C, and EBV infections can have reduced tear production, leading to the appearance of dry eye.
Certain systemic diseases such as dry syndrome (dry mouth, dental caries and mouth ulcers), rheumatoid arthritis, systemic lupus erythematosus, scleroderma, Sjogren’s syndrome, rosacea, Steven-Jonhson syndrome, scarring aspergillosis, diabetes, thyroid abnormalities, asthma and lupus erythematosus.
In addition, ocular excimer laser myopia correction surgery, corneal transplantation, eyelid surgery, orbital surgery, orbital radiation therapy and ocular contusion can cause dry eye, while severe dry eye can occur in recipients of allogeneic bone marrow or stem cell transplants with graft-versus-host disease.
8. Systemic drugs
Some antihypertensive drugs (including diuretics), antihistamines, antiglaucoma drugs, antiarrhythmic drugs, hormonal drugs, diphenoxylate/atropine, chemotherapy drugs, antidepressants and systemic application of retinoids and isotretinoin can reduce tear secretion and aggravate the symptoms caused by dry eye.
9 Long-term use of certain eye drops, such as vasoconstrictive eye drops (containing nalmivir ingredients), is also likely to form dry eye disease. Long-term eye cleaning solution, destroy the natural formation of tear film, thus aggravating the symptoms caused by dry eye.
10. Dysfunction of the lid gland, which reduces tear secretion and discharge, leads to dry eye.
☆ How do I know if I have dry eye disease?
With a score of >30 on the Symptom Score Test Scale
Early symptoms of dry eye disease may include: irritation, tearing, burning, pins and needles, dryness or foreign body sensation, mild itching, photophobia, blurred vision, inability to tolerate corneal contact lenses (contact lenses), eye redness, mucus discharge, increased frequency of transients, fluctuating daytime symptoms, and gradual worsening of symptoms during the day.
When you visit the doctor, in addition to examining your eyes, he or she will perform a number of tests on you, mainly the following.
1. Dry eye meter
To understand the lipid layer of the tear film. In dry eyes, especially in patients with LTD, abnormalities in the lipid layer of the tear film can be seen, which can be compared with standard images to predict the severity of dry eyes.
2. Anterior segment OCT
The tear river is the tear fluid that accumulates between the lower eyelid and the surface of the eye and contains 90% of the tear volume. Its height can reflect the tear volume, the function of the tear system and pathological changes, and is the gold standard for monitoring the severity of dry eyes, and the most classic method to determine the height of the tear river is to apply anterior segment OCT.
3. Schirmer test.
Also known as the tear secretion test, it is an examination of tear secretion. The physician will take a special filter paper sheet with one end folded back and gently place it into the junction of the middle and outer 1/3 of the lower lid capsule of the subject. This test is painless, but a few patients experience slight discomfort, but it does not affect vision. A strip of filter paper is placed into the conjunctival sac and removed after five minutes and the wet length is measured. It is generally considered normal to be 10-15mm, <10mm for hypersecretion, and <5m for dry eyes. Without ocular surface anesthesia, the secretion function of the primary lacrimal gland is tested; after surface anesthesia, the secretion function of the secondary lacrimal gland (basal secretion) is tested, and the observation time is the same 5 min.
4. tear film rupture time
Also known as BUT, is to check the function of the tear film, which is the first protective film covering the surface of the eye and has the role of lubricating, moistening, protecting, antibacterial and nourishing the surface of the eye. If the tear film is not stable, the eye will of course have problems.
5. Fluorescein staining and slit lamp photography
A positive fluorescein stain indicates a corneal epithelial defect, and the KangHua Slit Lamp System can quantify the extent of the epithelial defect on the surface of the eye and the height of the tear duct.
6. Corneal topography examination
To understand the regularity of the corneal surface, the corneal surface regularity parameters (surface regularity index and surface asymmetry index) are increased in patients with dry eyes compared to normal subjects, and the degree of increase is positively correlated with the severity of dry eyes.
7. biopsy and blot cytology
Patients with dry eye have decreased conjunctival cupped cell density, increased nucleoplasmic ratio, squamous epithelial cell metaplasia, and conjunctivalization of corneal epithelium. The severity of the disease can be assessed indirectly by calculating the density of cupped cells in the conjunctiva.
8. Serological examination
To understand the autoantibodies of, SS patients are long seen positive for ANA antibodies, rheumatoid factor, etc. This item is useful for the diagnosis of dry eye due to immune diseases.