LASIK corrective eye surgery is a type of refractive surgery for correcting myopia, hyperopia and astigmatism. LASIK or Laser Assisted In Situ Keratomileusis uses laser lights to fix your eyesight. Until the invention of contact lenses, eyeglasses alone were used to correct refractive vision errors. Modern techniques like Lasik, Photo refractive keratectomy (PRK) are performed for surgical insertion of artificial lenses to correct eyesight. Blurred vision is the failure of the eye's cornea and lens to refract light rays properly, which affects the images from being focused on the retina. Such blurriness is termed as refractive error. The major causes for refractive error include imperfectly shaped eyeball, cornea or lens.
The procedure involves permanently changing the shape of the cornea for better eyesight. Ophthalmologists use an excimer laser and special knife (microkeatome) to conduct the reshaping. You will be examined completely for any health related issues and the doctor also ensures that your eyes are healthy enough to undergo laser surgery. Few tests are done to measure the curve of the cornea, the size, and position of the pupils, the shape of the eyes and the thickness of the cornea. The tests enable the ophthalmologist to ensure that laser or LASIK eye surgery is an option to you. Ophthalmologists use a microkeratome, a special knife to cut a hinged flap of the corneal tissue. The flap is then folded to reach stroma, the middle section of the cornea, where actual reshaping takes place. An excimer laser is put into the stroma, to vaporize a predetermined portion of the cornea. In other words, pulses from the laser lights reshape the middle portion of the corneal tissue. Once the reshaping is done, the flap that was folded is replaced on the stroma. No stitching is required as both the tissue layers heal through natural process.
Macular degeneration is the predominant cause of vision loss in the elderly. However, the word senile macular degeneration is often misinterpreted with respect to age-related macular degeneration (AMD or ARMD). The macula of the eye enables the central vision process. Macular degeneration occurs in dry and wet forms respectively. The dry form is the non-exudative form where as the wet form is the exudative form. In some instances, the advance of AMD is so slow that people may even fail to notice a little change in their vision. Whereas, in others the disease spreads faster and may lead to loss of vision in both the eyes.
Non-exudative Macular degeneration
The extra cellular deposits which are called drusen accumulate under the retinal pigment lead to the dry form. Although they appear pleomorphic, under ophthalmoscopy they generally tend to appear as discrete yellow lesions which are clustered in the macula referred to as pseudo papilledema. The symptoms of macular degeneration include difficulty in reading, recognizing faces etc. The peripheral vision remains but deteriorates gradually.
These lesions gradually become larger leading to multiple conditions such as retinal epithelial atrophy and also loss of photoreceptor function which causes vision loss. The enlargement of these lesions also results in retinal vein occlusion. Treatment with vitamins such as beta carotene, vitamin C and also zinc may slow down the process of dry macular degeneration.
Exudative Macular degeneration
The wet form or the exudative macular degeneration is a rare form of the disease. It occurs when the neovascular vessels arising from the choroid grow through defects in Bruch's membrane into the potential space of the retinal pigment epithelium. When these blood vessels leak, the retina is elevated along with the pigment epithelium leading to distorted or blurred form of vision. The symptoms resulting are generally gradual. However bleeding resulting from the sub retinal choroidal neovascular membranes may lead to acute vision loss. The exudative changes in the eye include hemorrhages, hard exudates, sub retinal / intraretinal fluid. Atrophy caused may be both incipient and geographic in nature. In addition to this, there is also a condition called central scotomas which is generally noticed as the missing areas of vision.
The neovascular membrane is difficult to locate by fundus examination since the locus of the membrane is beneath the retina. Angiography pertaining to the use of fluorescein or indocyanine may yield good diagnostic results. Laser ablation followed by the Angiography may prevent the onset of exudative macular degeneration.
Signs and symptoms of Macular degeneration
In gradual muscular degeneration, vision change is noticed slowly. The symptoms usually developed are:
Treatment of Macular degeneration
The wet from of macular degeneration is more likely to cause significant vision loss than the dry from and therefore different treatments for wet forms are available. These could help decrease the amount of vision lost. Laser treatment may stop or lesson vision loss in early stages of the disease. This is performed with specific wavelength designed to cauterize the abnormal blood vessels. A laser beam destroys blood vessels and may stop the growth of new ones. A scar forms after the treatment and this produces a permanent vision loss in that area of retina sacrificed to preserve the rest of the eye layer. Only a small number of people qualify for laser treatment and for many, vision may not improve after laser treatment. Photo dynamic therapy uses a light activated drug called verteportin given intravenously to the patient. A special laser is used to close the abnormal vessels while the retina is left intact. As closed blood vessels can reopen within a treated area, this may be necessary for one or two years. Exposure to light/sunlight should be avoided for five days after treatment. There are a number of drugs that block vascular endothelial growth factor and thus used as a treatment option. These have shown improvement in vision and not just delay or arrest the loss of vision due to macular degeneration.
Although macular degeneration is associated with age, genes related to the degeneration process of the macula have much significance. Factors such as obesity, hypertension, and oxidative stress may cause macular degeneration. Cardiovascular disease may increase the risk of macular degeneration. Among all the risk factors, smoking is considered as the most potent cause of macular degeneration. The risk of this disease in smokers is three times more than the other factors.
Iridotomy involves focussed use of Laser on the iris of the eye for patients suffering from glaucoma. Laser iridotomy is used to prevent subacute closed-angle glaucoma and acute closed angle glaucoma. Iridotomy can be done as an outpatient procedure. First the eye is numbed and a small opening is made on the iris so as to reduce the pressure building within the eyeball. The patient wont go through any pain but some localized heat or pinching sensation. Complications that can arise with iridotomy are bleeding in the iris, blurred vision for a brief period and in rare cases loss of vision.
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Diseases, Symptoms, Tests and Treatment arranged in alphabetical order:
Bibliography / Reference
Collection of Pages - Last revised Date: November 19, 2019