The sclera is the outer, opaque fibrous layer of the eyeball, representing approximately 5\/6 of the ocular surface, which, together with the cornea, forms the outer protective shield of the eyeball and ensures its structural integrity. It is composed of densely packed, irregularly arranged collagen fibres (mainly type I collagen) and elastin, which gives it its characteristic white colour and high mechanical strength while being optically opaque - in contrast to the cornea, where the regular arrangement of collagen fibres provides transparency. The thickness of the sclera is variable, ranging from about 0.3 mm near the equator to 1.0 mm near the posterior pole and the site of attachment of the oculomotor muscles, being thinnest where the optic nerve passes through it, forming a structure called the lamina cribrosa.<\/p>\n\n\n\n
The sclera has key mechanical functions, including maintaining the shape of the eyeball, protecting delicate intraocular structures from mechanical damage and providing an attachment site for the six oculomotor muscles responsible for eye movements. It also acts as a barrier to intraocular pressure, preventing excessive stretching of the eye, although in some pathological conditions, such as high myopia<\/a> post\u0119puj\u0105ca lub wrodzona jaskra (buphthalmos), mo\u017ce ulega\u0107 patologicznemu wyd\u0142u\u017ceniu. W przednim odcinku tward\u00f3wka przechodzi w przezroczyst\u0105 rog\u00f3wk\u0119 w obszarze zwanym limbusem, gdzie znajduj\u0105 si\u0119 r\u00f3wnie\u017c struktury odpowiedzialne za drena\u017c cieczy wodnistej (splot \u017cylny tward\u00f3wki\/kana\u0142 Schlemma). Tward\u00f3wka jest s\u0142abo unaczyniona, z wyj\u0105tkiem powierzchownych warstw zaopatrywanych przez naczynia nadtward\u00f3wkowe i przytward\u00f3wkowe, co ma znaczenie w procesach zapalnych (zapalenie tward\u00f3wki \u2013 scleritis) oraz w chirurgii okulistycznej, gdzie stanowi miejsce wykonywania naci\u0119\u0107 i umieszczania szw\u00f3w w zabiegach takich jak witrektomia czy chirurgia retinal detachments<\/a>.<\/p>","protected":false},"featured_media":0,"parent":0,"template":"","meta":{"_acf_changed":false},"class_list":["post-4750","slownik","type-slownik","status-publish","hentry"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t