I. Etiology
Recent studies have identified changes in the ocular surface, immune-based inflammatory responses, apoptosis, and alterations in sex hormone levels as factors associated with the development of dry eye, while the relationship between the factors is not yet understood. The etiology can be divided into four categories as follows.
1. Insufficient tear secretion from the lacrimal gland in the aqueous layer
is the most common cause of dry eye angle; congenital absence of lacrimal gland, aging lacrimal gland function is reduced or some autoimmune diseases causing lacrimal gland inflammation, trauma, infection, autonomic dysregulation, long-term point certain eye drops or taking certain drugs can cause insufficient tear secretion; long-term contact lens wearers.
2. Insufficient secretion of the oil layer
Poor lid gland function due to eyelid disease.
3. Insufficient secretion of the mucin layer
Vitamin A1 deficiency, chronic conjunctivitis, chemical burns, etc.
4. Excessive evaporation of tears and uneven distribution of tear film
Poor eyelid closure due to eyelid disease, reduced blinking, prolonged stay in a cool room or in a hot and strong outdoor environment
II. Clinical manifestations
Other symptoms include burning, itching, photophobia, congestion, pain, blurred vision and fatigue, and mucous filiform discharge.
Examination
1.Tear secretion test
The normal value is 10-15mm, more than 10mm is low secretion, less than 5mm is dry eye.
2.Tear film rupture time
Less than 10 seconds is tear film instability.
3.Tear fern test
Mucin deficiency, such as ocular aspergillosis, Stevens-Johnson syndrome, the “fern” is reduced or even disappeared.
4.Biopsy and blot cytology
Patients with dry eye have reduced conjunctival cupped cell density, increased nucleoplasmic ratio, squamous epithelial cell metaplasia, and conjunctivalization of the corneal epithelium. The severity of the disease can be indirectly assessed by calculating the density of cupped cells in the conjunctiva.
5.Fluorescein staining
Positive represents a corneal epithelial defect. The height of the tear river can also be observed.
6.Tiger red staining
Sensitivity higher than fluorescein staining, corneal and conjunctival inactivated cells stained as positive cells.
7.Tear lysozyme content
The content <1200μg/ml, or lysis zone <21.5mm2, is indicative of dry eye.
8.Tear osmolarity
In dry eye and contact lens wearers, tear osmolarity increases by 25 mOsm/L compared to normal. if it is greater than 312 mOsm/L, dry eye can be diagnosed.
9.Lactoferrin
Patients younger than 69 years old can be diagnosed with dry eye if it is less than 1.04 bg/ml and patients over 70 years old if it is less than 0.85 mg/ml.
10.Tear clearance test
The purpose is to find out whether there is any delay in tear clearance. It should be detected by fluorophotometric method.
11.Dry eye meter or tear film interferometric imager
To understand the lipid layer of the tear film, abnormalities in the lipid layer of the tear film can be seen in patients with dry eye, especially in LTD (lipid deficient dry eye), and the severity of dry eye can be inferred by comparing with standard images.
12.Corneal topography examination
To understand the regularity of corneal surface, the regular parameter of corneal surface is higher than normal in dry eye patients, and the higher the parameter, the more severe the dry eye.
13.Serological examination
To understand the autoantibodies, ANA antibodies and rheumatoid factor etc. are seen to be positive in patients with dry eye syndrome. This item is beneficial to the diagnosis of dry eye caused by immune diseases.
IV. Treatment
Dry eye disease is a chronic disease and mostly requires long-term treatment. If the dry eye is due to excessive tear evaporation caused by eyelid exposure, the timing of eyelid reconstruction surgery should be grasped for eyelid reconstruction according to the condition.
1. Local treatment
(1) Eliminate triggers Avoid prolonged use of computers, less exposure to air conditioning and smoky environments, and other dry eye triggers; those with lid gland dysfunction should pay attention to eyelid cleaning and antibiotics.
(2) Replacement treatment of tear components Apply autologous serum or artificial tears; severe patients should try to use artificial tears without preservatives.
(3) Prolong the residence time of tears on the eye surface Wet room lenses, silicone eye shields, therapeutic corneal contact lenses, etc. can be prescribed.
(4)Others
Avoid taking drugs that can reduce tear secretion, such as hypotensive drugs, antidepressants, atropine analogues, etc.; types with immune factors involved can be added with immunosuppressants or short-term topical hormones; surgical treatment, etc.
2.Systemic treatment
Mainly to improve the nutritional status of patients and prevent secondary infection. Consume foods rich in vitamin A, such as milk, eggs, vegetables containing carotene; oral cod liver oil, etc.
There is no effective treatment. To reduce pain frequent drops of saline, artificial tears or antibiotic eye ointment can be administered; or small tear dots can be closed with electrocautery to reduce tear outflow. For dry eyes due to incomplete eyelid closure, blepharoplasty is feasible.