What is retina?
The retina is a tissue that lines the inner surface of theeye and it is sensitive to the light. The images of the visual world getcreated on the retina by the complex optics of the eye. When the light reachesthe retina in then triggers, a number of electrical and chemical events theninitiate a series of nerve impulses which get sent to different visual centersof the brain. These nerve impulses are transported by means of fibers locatedin the optic nerve. During the embryonic development the optic nerve and theretina are characterized as the outgrowths of the developing brain. This is whyretina is considered as one of the main parts of the central nervous system. Itis also a peculiar fact that it is the only part of the central nervous systemwhich can be seen without any invasive procedures. It has different layers ofneurons which are connected by synapses, but the only types of neurons whichare characterized by sensitivity to direct light are the so calledphotoreceptor cells. There are two different types of such cells and thoseinclude the cones and rods. The cones are in charge of supporting normaldaytime vision and proper perception of colors, while the rods are in charge ofsituations when there is only dim light and they also provide black and whitevision. There is also the third type of photoreceptor cell which is not thatcommon and it is referred to as photosensitive ganglion cell. It is in chargeof all different reflexive responses to bright daylight. Other neurons locatedin the retina are in charge of processing the signals received from the conesand the rods.
Different retinal diseases
Since retina is such a gentle part of the human body it maybe affected by numerous different types of acquired or inherited disorders orother medical conditions. For example, lipemia retinalis is a certain type ofwhite appearance on the retina, retinoblastoma is a cancer of the retina, Conerod dystrophy is a disease in which the vision gets deteriorated, macular degenerationis a group of diseases in which the central vision gets lost, retinitispigmentosa is group of diseases characterized by a loss of peripheral and nightvision, retinal separation involves the detachment of the retina from the backof the eyeball, and there are many others. Angioid streaks are among the mostcommon medical conditions which affect the retina and they are actually smallcracks in it and they may often lead to the formation of scars. This may leadto vision problems and other medical conditions such as Sickle cell disease,Paget’s disease, gastrointestinal bleeding, heart difficulties andpseudoxanthoma elasticum. Central retinal artery occlusion is a medicalcondition in which the main artery which supplies the retina with blood getsblocked and the retina soon dies. Another relatively common medical conditionknown for affecting the retina is called central serous retinopathy. It is characterizedby a small blister of fluid underneath the retina which can be held responsiblefor the visual distortion, faded color vision and blurry vision. Choroidaldetachment is a medical condition in which the blood or the serum lifts up thechoroid. On the list of common medical conditions which may affect the retinais the one known as hypertensive retinopathy. In this type of condition theblood vessels which are responsible for the nourishment of the retina areabnormal. The retina commonly gets damaged. One of the most common medicalconditions associated with retina is the retinal detachment. This is a veryserious medical problem in which the retina gets separated from the back of theeye. If it does not get treated on time, the person usually loses the visioncompletely. Different treatment options include surgical repairs along withlaser or freezing treatments. In most cases the retina can be reattached to theback of the eye, but that does not mean that the vision will be restored. Retinitispigmentosa is a medical condition in which the night vision gets reduced. Othercommon symptoms of this condition may also include blurred central vision,narrowed visual fields and restricted visual fields. There are different typesof retinitis pigmentosa and each one of them has different characteristics. Another medical condition associated withretina is a retinal tear in which the vitreous jelly gets contracted and pulledaway from the retina. Once this occurs it also causes a tear to occur. This canbe a very serious medical problem and it may even lead to subsequent loss ofvision. The last medical condition on the list of conditions known foraffecting the retina is the one known as retinoschisis. In this condition theretina splits into two layers but it rarely involves any symptoms or problems.