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Анатомия на окото За да попадне светлината в окото, първо трябва да премине през роговицата - най-предната прозрачна част на зрителния орган. Тя осигурява шестдесет процента от диоптричната (пречупвателната) сила на окото. След пречупването на светлинните лъчи от роговицата те преминават през зеницата. Тя представлява отвор на ириса, променящ се според интензивността на светлината. Ирисът от своя страна придава цвета на окото. След зеницата светлината преминава през лещата, която има способността да променя пречупвателната си сила в зависимост от отдалечеността на наблюдавания предмет, като по този начин спомага, получаваният образ винаги да бъде на фокус. При нормалните очи след лещата светлината преминава през стъкловидното тяло - гелообразна структура, която изпълва окото отвътре и му придава сферична форма. Най-накрая образът от наблюдавания предмет попада върху ретината във фокусиран вид. Централната част на ретината, отговаряща за ясното виждане, се нарича макула. Ретината е изградена от милиони светлочувствителни клетки, най-вътрешната част от които, с дългите си нервни окончания, образуват снопа на зрителния нерв. Зрителният нерв предава зрителните дразнения към мозъка, където те се възприемат като образ.
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Eye Surgery Cataracts A cataract is the clouding of the normally clear, natural crystalline lens of the eye. The lens is composed of water and protein. The protein is arranged in a highly organized pattern that allows light to pass through it with minimal distortion. As a result, the lens appears virtually clear. The lens can become cloudy, blocking or scattering some light and preventing it from reaching the retina in sharp focus. This causes blurred vision and glare. Most cataracts progress slowly over a period of years, but their rate of progression is unpredictable. They can affect one eye or both eyes. Cataract Surgery At present the only treatment for a cataract is surgical removal. Fortunately, there have been tremendous advances in cataract surgery in the past several years. The chance of recovering good vision after surgery is now excellent, although complications can occur in one to three percent of patients. There is remarkably very little discomfort after cataract surgery. The most common method of cataract removal is Phacoemulsification. In this technique a tiny vibrating ultrasonic probe creates high energy sound waves that break the cataract into smaller particles. These particles are gently suctioned out of the eye. Using a small incision speeds up healing after surgery. The preferred method to restore vision for nearly all of our patients after cataract removal is to implant an intraocular lens implant into the eye at the time of surgery. This clear artificial implant is placed in the eye behind the iris and pupil in the same position as the natural lens, and it stays in the eye permanently. Implanting an intraocular lens adds little additional risk to the surgery. Recent developments in the intraocular lens industry have now provided us with multifocal lenses that allow patients to see distance as well as near vision without glasses. Patients now have a number of lens options to choose from. Patients who have certain unusual eye conditions might not be good candidates for intraocular lens implantation. We will discuss this with you when planning your surgery. Retinal Surgery The cornea and lens focus light onto the retina, the transparent, light-sensitive membrane on the inner surface of the back of the eye. The central area of the retina, called the macula, primarily contains a high density of color-sensitive photoreceptor cells. These cells, called cones, produce the sharpest visual images and are responsible for central vision. The peripheral area of the retina, which surrounds the macula, contains photoreceptor cells called rods, which respond to lower lighting levels but are not color sensitive. The rods are responsible for peripheral vision and night vision. The optic nerve carries signals generated by the photoreceptors (cones and rods). Each photoreceptor sends a tiny branch to join the optic nerve. The optic nerve extends into the brain and connects to neurons that carry signals to the vision center of the brain, where they are interpreted as visual images. The optic nerve and the retina have a rich supply of blood vessels that carry blood and oxygen. Part of this supply of blood vessels comes from the choroid, which is the layer of blood vessels that lies between the retina and the outer white coat of the eye (the sclera). The central retinal artery (the other major source of blood to the retina) reaches the retina near the optic nerve and then branches out within the retina. Diseases of the Retina Diseases of the retina include: - Central Serous Chorioretinopathy - Coats' Disease - Vitreoretinopathy - Floaters - Leber's Congenital Amaurosis - Macular Degeneration - Macular Hole - Macular Pucker - Retinal Detachment - Torn Retina - Vitreous Detachment - Retinitis Pigmentosa - Retinopathy of Prematurity - Retinoschisis - Vascular Disorders of the Retina Retinal Surgery Retinal surgeries include Epiretinal Membrane Peeling (Membranectomy), Proliferative Vitreoretinopathy Treatment and Vitrectomy. To find a surgeon at Trinity visit Find a Doctor.