Editor's Note
From May 12th to 15th, the 15th National Academic Conference on Corneal and Ocular Surface Diseases and the 8th National Corneal Refractive Surgery Conference were held in Jinan, "Quancheng". The conference is mainly based on corneal diseases, and invited top corneal experts from the Asia-Pacific region and many domestic corneal disease experts to attend the meeting and deliver wonderful special lectures. The content of the conference was wonderful, covering a total of eight topics related to the eye table. At the lecture on dry eyes, eye surfaces, tear organs and external eye diseases on May 14, Professor Yan Xiaoming from Peking University First Hospital gave a wonderful speech on "Instantaneous Eyes and Eye Tables". Professor Yan Xiaoming systematically and comprehensively introduced the damage to the ocular surface of the eye and the pathogenesis and treatment methods of the ophthalmic surface diseases related to the transient eye, bringing everyone a new understanding of the "instantaneous".
Yan Xiaoming, chief physician, professor and doctoral supervisor, is currently the director of the Ophthalmology Center of peking university first hospital, the deputy director of the ophthalmology center of Peking University, the deputy director of the Department of Ophthalmology of Peking University, the vice chairman of the Keratopathy Medical Expert Committee of the Beijing Medical Reward Foundation, the standing committee member of the Ophthalmology Professional Committee of the Beijing Medical Association, the member of the 8th, 9th and 10th Chinese Medical Association Ophthalmology Branch Keratology Group, the member of the Asian Dry Eye Association, the member of the Ophthalmology Expert Committee of the Chinese Association of Women Physicians, and the editorial board of several ophthalmic professional magazines. He specializes in the diagnosis and treatment of ocular surface and corneal diseases, myopia and cataracts, including corneal transplantation, excimer laser surgery and cataract phacoemulsification.
Expert Profiles
Instantaneous
The transient eye is an involuntary equal closing and opening movement of the eyelids involved by the orbicularis orbicularis muscles of the eyelids and the lifting eyelid muscles. Under natural conditions, the number of instantaneous glances per minute is about 10 to 15 times, with an average of one instantaneous glance every 5 seconds, and the duration is about 0.3 to 0.4 seconds. The more precise time per eye is measured by Doane: a total time of 258 milliseconds per instant, 82 milliseconds for eye closure and 176 milliseconds for eye opening.
Transient is a protective measure that coats tear fluid to form a tear film that lubricates the cornea, maintains normal functioning of the eye surface and prevents foreign bodies from invading.
Under normal circumstances, the instantaneous frequency is 10 to 15 times / min, 10 times / min when reading a book, 4 to 6 times / min when watching a computer, and 2 to 3 times / min when driving or playing a game. In addition, factors that affect the frequency of the eye are age, ocular surface state, mental state, neurological and psychological diseases, etc.
Transient is involuntary eyelid movement, which is completed by the eyelid orbicularis muscles (orbicularis orbicularis muscles in the front of the tarsal plate and the orbicularis orbicularis muscles of the orbital septum) and the upper eyelid muscles, with a coordinated movement of contraction and another diastolic. Corresponding to the transient eye are the autonomous closed eye movements produced by orbital orbicularis muscle movements, including blinking and eyelid spasms.
Figure 1. Dissection associated with the transient eye
By detecting the movement of the levator and orbicularis orbicularis muscles, the active and passive processes of the instantaneous upper eyelid movement can be divided into the descending phase and the ascending phase: the contraction of the orbicularis orbicularis muscle in the descending phase, the inhibition of the levator blepharhoid muscle in the ascending phase and the inhibition of the orbicularis orbicularis muscle in the ascending phase [1].
Figure 2: The active and passive processes of eyelid movement during the instantaneous eye
Instantaneous and eye watch
The 2007 International Working Group on Dry Eye divides the ocular surface system into corneal epithelium, lacrimal glands, paracrimal glands, meibomian glands, tear membranes, basal connective tissue, conjunctiva and their appendage glands (moll and Zeiss glands), as well as transient eyelid components and nasolacrimal tracts, where the corneal epithelium, tear glands, paracrimal glands, and meibomian glands all produce tear film components [2]. These structures are interconnected and regulated by lacrimal, hormonal, blood, nerve, cytokine, light, and eyelid movements.
Eyelid dynamics (transient), stable tear film, healthy ocular epithelium, and moderate pressure on the eyeball by the eyelids are important for maintaining a normal ocular surface. Potential spaces for ocular friction include the upper eyelid and eyeball, the tear film and the ocular surface, and the conjunctival matrix and sclera [3]. When the lubrication function of the eye surface is abnormal, the relationship between the potential spaces of the three pairs of mutual friction is broken, and the lubrication between the above tissues is reduced and the friction is increased in an instant, and the friction increases in turn, which in turn causes damage and inflammation to the surface tissue of the eye, resulting in a series of ocular surface diseases.
In 1904, Parsons et al. proposed the hypothesis that the eyelid brush would be in contact with the surface of the eyeball. The eyelid brush is a squamous epithelial area at the upper eyelid margin, starting behind the opening of the meibomian gland and ending in the subsection of the tarsal plate, where the multilayered squamous epithelium transitions from keratinized to non-keratinized [4]. Tissue staining of eyelid brushes revealed that their complex squamous epithelium contains a large number of MUC5AC-positive epithelial cells, or goblet cells[5]. The laminated squamous epithelium is often located in areas that are often rubbed, such as the cornea, skin, and oral mucosa.
In 1965, Ehlers et al. found that only the squamous part of the upper eyelid is in contact with the eyeball during the transient eye, and the epithelium in contact with the eyeball is twice as thick as the other parts of the upper eyelid. In 1967, Kessing et al. used an inconjunctival sac barium sulfate to find that only the upper eyelid margin and all areas of the lower eyelid came into contact with the eyeball [6].
Figure 3. Eyelid brush
Transient and ocular surface injuries
Eyelid or conjunctival diseases can lead to an instantaneous increase in friction, resulting in damage to the epithelium of the ocular surface, reducing transmembrane mucin, thereby decreasing epithelial wetness and decreasing the stability of the tear film; and a decrease in the stability of the tear film can lead to an increase in the osmolal pressure of the tear membrane, resulting in inflammation of the ocular surface, aggravating the damage to the epithelium of the ocular surface, and forming a vicious circle. In addition, damage to the epithelium of the ocular surface further increases transient friction.
Figure 4: Transient and ocular surface injuries
Ocular surface diseases associated with transient eyes
Ocular surface diseases related to the transient eye include primary and secondary, primary ocular surface diseases include eyelid brush epithelial lesions (LWE), dry eyes, conjunctival relaxation, SLK, filamentous keratitis and shield corneal ulcers, etc., secondary ocular surface diseases include eyelid abnormalities of various causes (posterior blepharitis, eyelid overlap syndrome, etc.), scarring conjunctivitis, corneal epithelial malnutrition, persistent corneal epithelial defects and surgically originated ocular surface changes (corneal transplantation, corneal refractive surgery).
1. Eyelid brush epithelial lesions
Lid Wiper Epitheliopathy (LWE), as the name suggests, is an epithelial lesion in the brush area of the eyelid that presents with dry eyes, a foreign body sensation, a feeling of friction, pain, irritation, burning, or tears. Severe patient examination may reveal congestion in the brush area of the eyelids, positive for fluorescein or Bengal rose staining. [7,8]
Figure 5. LWE
2. Dry eyes
When the eyes are dry, a decrease in tear production or excessive evaporation of tear fluid will lead to an increase in the osmolality of the tear film, resulting in an inflammatory response that damages the eye surface; while the instantaneous friction can further aggravate the damage of the inflammation of the eye surface, increase the instability of the tear film, and participate in a vicious circle.
Figure 6. Relationship between friction and dry eye-related inflammation
3. Conjunctival relaxation
In patients with conjunctival laxity (CCh), decreased adhesion of the bulbous conjunctiva to the subconjunctival tissue, decreased conjunctival sac volume, delayed tear removal, and transient-related micro-injuries, lacrimation, accumulation of metabolites, and inflammatory responses due to transient damage, and conjunctival edema. The causal relationship between conjunctival relaxation and friction is unclear, and it has been clinically found that foreign body sensation is more pronounced in patients with early conjunctival relaxation than in patients with severe or long-term conjunctival laxity, which may indicate that early eyelid friction is more pronounced.
4. Keratoconjunctivitis of the upper corneal margin
Superior limbic keratoconjunctivitis (SLK) is a recurrent chronic corneal inflammation of the upper blepharoconjunctiva, the superior bulbous conjunctiva, the upper corneal margin, and adjacent corneas, with multiple binocular disease, more common in middle-aged women, and most patient lesions that disappear spontaneously. Studies have found that 26 to 50% of patients with SLK have abnormal thyroid disease, and 1/4 to 1/2 of patients with SLK have dry eyes.
The pathological mechanism of SLK is relaxation of the upper bulbous conjunctiva and an increase in eyelid tension, resulting in continuous friction between the upper bleral conjunctiva and the upper bulbous conjunctiva, resulting in chronic inflammation of the bulbous conjunctiva and the appearance of tear membrane abnormalities [9,10], of which the inflammation of the bulbous conjunctiva is more pronounced. Clinical features of SLK are persistent burning or foreign body sensation; hyperemia, thickening, laxity, and lack of luster in the upper bulbous conjunctiva on examination; positive FI, tiger red, or lisamine green staining; annular bulge and fold of the conjunctiva at the upper corneal margin; fine velvety papillary and keratosis of the upper conjunctiva; superior filamentous keratitis (1/3), SPK, and occasional vascular fessels.
Figure 7. Clinical features of SLK
5. Filamentous keratitis
Causes of filamentous keratitis include abnormal proliferation of epithelial cells, abnormal binding of the basement membrane to the anterior elastic layer, excessive mucus-like formation (eg, dry eye, viral infection, neurotrophic keratitis, scarred keratitis), corneal abrasions, corneal contact lens wearing, and postoperative bandaging of the inner eye. It is characterized by a chronic, recurrent course of the disease, showing foreign body sensation and pain, and multiple filament cords (composed of denatured epithelium and mucus) on the surface of the cornea can be seen on examination, which can be seen in any part but above. In addition, patients with filamentous keratitis are often accompanied by manifestations of dry eyes.
Mechanisms of filament formation in filamentitis include damage to the basal cells, basal, or Bowmen layers of the corneal epithelium, which detaches the basal membrane; uplifts the damaged area under the action of transient shear force of the eyelid; the raised basal membrane allows mucin and denatured epithelial cells to aggregate to form corneal filaments; and irregularities in the corneal surface exacerbate corneal inflammation and stimulate an increase in mucin [11,12].
Figure 8. Filamentitis keratitis: mechanism of filament formation
6. Shield corneal ulcer
Shield corneal ulcers are seen in patients with spring keratitis and specific keratitis, caused by mechanical friction of the huge papillae of the upper eyelid.
Figure 9. Shield-shaped corneal ulcer
Treatment of transient-related ocular surface diseases
Treatment of transient-related ocular surface diseases includes: improving transient eyes to reduce friction; stabilizing the tear film with artificial tear fluid or wet room mirrors; controlling inflammation with hormones, nonsteroidal anti-inflammatory drugs, cyclosporine A, FK506, etc.; using bandage mirrors, calf serum, growth factors, etc. to promote epithelial repair; and surgical treatment.
Professor Yan Xiaoming shared 3 clinical cases to illustrate the treatment of transient eye-related ocular surface diseases.
Figure 10. Case 1: In patients with LWE, symptom relief was seen after 2 weeks of treatment with lubricant, but symptoms worsened again after 2 weeks of discontinuation. Short-term use of artificial tear fluid does not remove the cause of LWE and requires extended follow-up for further observation.
Fig. 11.Case 2: A patient with SLK in the left eye, who has suffered from Hashimoto's disease for many years, was given flumirone (FML) and Siran eye drops three times a day, and the patient's symptoms were alleviated after 1 week of treatment.
Figure 12.Case 3: Patients with filamentous keratitis in the right eye, both eyes MGD; defilament treatment, bandage mirror bandage, and warm compresses, massage, clean eyelids; drug selection of fusidic acid eyelid margin twice a day, Punan chlorpyriflor and sea dew eye drops three times a day. After 2 days of treatment, the symptoms of re-examination were significantly reduced.
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