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An understanding of the basic anatomy and physiology of the eyelids is important since so many common ophthalmic problems are encountered in this area ,especially in dogs , but less frequently in cats and rabbits as well. The tremendous variation in conformation exacerbated by selective breeding for specific appearance has contributed to the numerous pathological conditions in the area. These can be primarily ocular ,such as entropion (rolling in of the eyelids) or distichiasis (extra eyelashes along the eyelid margin) or can be secondary to skin diseases or immune-mediated conditions for example. 在眼睑方面有很多常见的问题，所以要熟知眼睑基本的解剖和生理学知识，尤其是对于犬这类动物，相较而言，猫和兔子在这方面并不是有很多常见病。人们对特定外观的选择性育种加剧了动物外表的巨大改变，为这个方面提供了很多病理学症状。这些症状可能主要表现在眼部，如眼睑内翻，双行睫（沿眼睑缘有额外的睫毛），或者继发于皮肤疾病，或者有免疫介导的病征。 The eyelids are dorsal and ventral folds of skin lined with palpebral conjunctiva and they form the palpebral fissure in which the globe is situated (Figure 3.1). The normal outline of the palpebral fissure is almond shaped (Figure 3.2) but many different variations occur with pedigree animals. The skin should be only loosely adherent to underlying structures but again this can vary from being excessively loose (e.g. in the saint bernard) to being very tight（e.g. The miniature poodle）.The upper eyelid is more mobile than the lower in most species. A fibrous layer for support, the tarsal plate, is present within the eyelids. This is less well developed in dogs than cats. 眼睑是有睑结膜为内衬的皮肤背侧和腹侧的皱褶，而且他们在眼球存在的位置形成睑裂。睑裂的正常轮廓是杏仁状（图3.2），但是纯种动物会出现很多不同变化。这些皮肤与底层结构松散连接，但是也可能出现过度宽松（圣伯纳），或者非常紧张（微型狮子狗）。大多数物种上眼睑比下眼睑更具移动性。眼睑内存在睑板纤维层的支持，狗没有猫发达。
In addition to providing support, the eyelid folds also contain both smooth and striated muscles and a good vascular and nerve supply. The most important muscle is the orbicularis oculi. The orbicularis oculi is mainly involved with eyelid closure and acts as a sphincter .It is located immediately below the skin and is innervated by the palpebral branch of the facial nerve (cranial nerve VII). Eyelid sensation is provided by branches of the trigeminal nerve (cranial nerve V). The usual rapid action of this muscle is important for globe protection and in the severe blepharospasm as the orbicularis oculi remains tightly contracted which can lead to further ocular pain with entropion and ulceration. 除了提供支持，眼睑皱褶中还有平滑的横纹肌，良好血管和神经供应。最重要的肌肉是眼轮匝肌。眼轮匝肌主要涉及眼睑闭合，并且充当括约肌。它紧接在皮肤的下方，通过面神经（第七对脑神经）的眼睑分支支配。眼睑的感觉是由三叉神经（颅神经V）的分支支配。眼睑可以快速反应来保护眼球，也会在眼轮匝肌紧密收缩时引起严重的眼睑痉挛，但是这可能导致进一步的眼睛疼痛并伴有睑内翻或者溃疡。 The normal position of the eyelids is resting against the ocular surface, and they slide over it during blinking .Many breeds of dogs and cats have poor lid-globe apposition and this results in ocular problems such as entropion or ectropion. 正常眼睑的位置紧靠着眼球表面，在眨眼期间，眼睑滑过眼球表面。许多品种的都有眼睑眼球覆盖不全的问题，这是导致某些眼病的原因，例如：眼睑内翻和眼睑外翻。 Palpebral ligaments are present medially and laterally and these fibrous bands stabilize the lids and help to maintain the shape of the palpebral fissure. The medial canthal ligament is well developed and having originated from the medial fibres of the orbicularis oculi muscle it inserts on the orbital rim of the lacrimal bone. In most dogs the lateral canthal ligament is poorly developed and really consists of lateral fascial attachments only. However, in some breeds ,particularly those with broad skulls and relatively deep-set eyes such as the Rottweiler and mastiff types, the lateral canthal ligament is more defined but misdirected medially, resulting in some lateral canthal involution .This needs to be addressed when considering entropion surgery in these breeds and is mentioned in the case on complicated entropion later in this section. 眼睑韧带存在于眼睑的内外侧，这些纤维保证了眼睑的稳定并且有助于保持眼睑裂的形状。内眦韧带发达并且来源于插入泪骨眶缘的眼轮匝肌内侧纤维。大多数狗外眦韧带发育不良，有些只有外侧肌筋膜附属器。然而，某些品种，特别是那些宽头犬种，它们的眼睛通常相对深陷，如：罗威纳和藏獒，外眦韧带更轮廓分明，但是内侧有问题，导致部分外眦退化。在处理这些品种犬的眼睑内翻手术时需要考虑问题。 Along the free margin of the lids (especially the upper lid)are a row of cilia (not true eyelashes). These are located close to, but actually on ,the eyelid margin . Within the eyelid margins are meibomian glands (also called tarsal glands) which secrete the oily (lipid) portion of the tear film.Their openings can be seen as a series of small grey dots (the grey line) along the eyelid margin . The eyelid margin itself is normally totally free from hairs and can be pigmented . The eyelid skin is very thin and easily becomes inflamed and oedematous (numerous mast cells within it contribute to this )- thus many clinical problems can occur in this area. 沿着眼睑的游离缘（尤其是上眼睑）是一排睫毛（非真睫毛）。这些位置靠近，但实际上，是指眼睑缘。眼睑边缘是睑板腺，睑板腺主要作用是分泌泪膜之中的油膜部分（脂肪）。它们的开口是一系列沿着眼睑缘的小灰点（灰线）。眼睑本身通常与毛发完全分离，可以被着色。眼睑皮肤很薄，容易发炎水肿（因为眼睑中存在大量的肥大细胞），因此许多临床问题发生在这个区域。 The eyelid have several functions. Clearly protection is important, along with the distribution of the tear film (assisting corneal nutrition) and propulsion of tears towards the nasolacrimal punctae for drainage. Foreign bodies such as dust and debris are removed via blinking. Closure of the eyelids reduces visual stimuli and assists sleeping while the cilia around the eyelids are important tactile organs. 眼睑有几个功能。1.保护的功能是非常重要的，伴随着泪膜的分布（辅助角膜营养），推进泪水到鼻泪管泪点处。2.异物如灰尘和碎屑都是通过眨眼消除的。3.眼睑闭合减少了视觉刺激，有助于睡眠，眼睑周围的睫毛是重要的触觉器官。 The third eyelid or nictitating membrane (membrana nictitans) is a ventromedial fold of conjunctive containing a T-shaped cartilage for support and the nictitans gland at its base (which together with the lacrimal gland produces the aqueous portion of the tear film). In addition to the nictitans gland ,a true Harderian gland is present in rabbits, which secretes a more oily contribution to the tear film.The nictitans gland is attached to the cartilage of the third eyelid and the ventral periorbita by loose connective tissue. 第三眼睑或瞬膜是结膜腹侧的一个折叠结构，含有一个支持——T形软骨，在它的底部有瞬膜腺（与泪腺一层产生泪膜的水层）。除了瞬膜腺，兔子还有一个哈氏腺，它分泌油脂，是泪液膜油层更丰富。瞬膜腺附着在第三眼睑软骨和疏松结缔组织的腹侧眶骨膜上。 The leading edge of the third eyelid is often pigmented ;however, in some dogs, particularly those with parti-coloured coats ,one eye might have a pigmented border while the other is nonpigmented. This is a completely normal variation and should not be confused with inflammation (the pink third eyelid is more noticeable against the darker colour of the iris than the pigmented one and owners often think that the dog has conjunctivitis in one eye!) .The third eyelid sweeps across the globe during blinking and assists in spreading the tear film and removing debris. It can be liked to a windscreen wiper in this respect. Unlike dogs, cats have some striated muscle fibres present within their third eyelids ,which allow for active protrusion of the membrane. 第三眼睑前缘常常是着色的，但是，有一些狗，特别是杂色皮毛犬，有可能出现一只眼睛的第三眼睑前缘为有色的，另一只眼睛为无色的。这是正常变化，不要与炎症混淆（对比深色眼睑来说，粉色的第三眼睑使虹膜更加明显，所以通常主人会认为狗只有一只眼睛有结膜炎）。眨眼时，第三眼睑扫过整个眼球的范围，协助扩散泪膜和清除杂物。它相当于这方面的雨刮器。与犬不同的是，猫的第三眼睑存在横纹肌，使瞬膜可以主动突出。 The most common conditions affecting the eyelids include abnormalities in eyelid position, inappropriate include abnormalities eyelashes and prolapse of the gland of the third eyelid, all of which will be discussed together with blepharitis ,since the latter can be overlooked in general practice or misdiagnosed as purely conjunctives with understandably limited response to treatment. 影响眼睑最常见的情况包括眼睑位置的异常，包括睫毛异常和第三眼睑腺脱出，这些与眼睑缘炎症都要讨论，因为眼睑缘炎症一般情况下会被忽视或误诊为结膜相关炎症的治疗反应
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发表于 2016-7-26 02:44:48
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