Tuesday, September 5, 2017

Laser Eye Surgery

Many people who have eye damage always seek what the best cure system. The result of many cure model still don’t make satisfactory yet. If you're looking for an alternative option to glasses or contact lenses, laser eye surgery could be the ideal solution. Laser eye surgery is an eye treatment that has given millions of people freedom from the need to wear glasses and contact lenses.

LASIK or Lasik is a type of refractive surgery for correcting myopia, hyperopia, and astigmatism. LASIK is performed by ophthalmologists using a laser The procedure is generally preferred to photorefractive keratectomy, PRK, (also called ASA, Advanced Surface Ablation) because it requires less time for the patient's recovery, and the patient feels less pain overall. However, there are instances where a PRK/ASA procedure is medically justified as being a better alternative to LASIK

Many patients choose LASIK as an alternative to wearing corrective eyeglasses or contact lenses. This technology have been apply by the Colombia-based Spanish ophthalmologist Jose Barraquer, who, around 1950 in his clinic in Bogotá, Colombia, developed the first microkeratome, and developed the technique used to cut thin flaps in the cornea and alter its shape, in a procedure he called keratomileusis. Stephan Schaller assisted in this landmark procedure. Barraquer also researched the question of how much of the cornea had to be left unaltered to provide stable long-term results.

This technology then improve and other country also interest to this technology. Russia in the 1970s by Svyatoslav Fyodorov, and PRK (photorefractive keratectomy), developed in 1983 at Columbia University by Dr. Steven Trokel, who in addition published an article in the American Journal of Ophthalmology in 1983 outlining the potential benefits of using the Excimer laser in refractive surgeries. (RK is a procedure in which radial corneal cuts are made, typically using a micrometer diamond knife, and is completely different from LASIK).

In the United Stated this technique use on June 20, 1989. "Method for modifying corneal curvature," encompassing the surgical procedure in which a flap is cut in the cornea and pulled back to expose the corneal bed. The exposed surface is then ablated to the desired shape with an Excimer laser, after which the flap is replaced.

LASIK surgery may need of one day be replaced by intrastromal ablation via all-femtosecond correction (like Femtosecond Lenticule Extraction, FLIVC, or IntraCOR), or other techniques that avoid weakening the cornea with large incisions and deliver less energy to surrounding tissues. The 20/10 FEMTEC laser has recently been used for incision-less ablation on several hundred human eyes and achieved very successful results for presbyopia, with trials ongoing for myopia and other disorders.

Myopia or Nearsightedness

Myopia, or nearsightedness, is an error of refraction in the eye that causes objects more than a short distance away to appear blurred. It usually result from the cornea of the eye being too far from the retina, so that images are focused in front of the retina.

The error can be corrected for by concave Eye Diseases or by contact lenses, severe cases of myopia are sometimes treated by a controversial surgical distortion of the cornea known as radial keratotomy.

Many thousand people are suffer of this eye error, nearsightedness make people difficult to see something in distance such as highway sign, or object in a distance, but can see for close object and can work easily for close object like sewing.

To correct this error people can use a eye glasses or contact lens, but currently the technology have improved using eye laser surgery. The kind of this surgery as follows:
PRK is laser eye surgery that removes a layer of corneal tissue, which flattens the cornea and allows light rays to focus closer to or even on the retina.

LASIK is the most common refractive procedure a flap is cut through the top of the cornea, a laser removes some corneal tissue, and then the flap is dropped back into place.

Many Kind of Animals Eyes

Animals eyes are classified vary on this world. Eyes are an organ that base on the light come different each others, there are about 32 kind on animals world, that principally different work. The most complete of eyes like a camera that can absorb of wide spectrum like on primate such as monkey and human.

Eyes model of many animals is vary, and for human all eyes is located in the fronts that sometime have a blind spot area that cannot be seen. If we lay 2 same drawing of cat or other drawing with a distance of about 15 cm, then locate in front about one arm, close one of your eyes then move that drawing close to eyes slowly, on certain distance then one of the drawing will lost.

Octopus eye is an example of better eyes structure than primate in, the blood vessel located before the light recipient. So the octopus eye design is better than the human eye!

Our eyes are an advance design because can use as camera SLR and autofocus, auto exposure (fast adapt from dark to light by opening the diaphragm). If on the insect eyes they cannot adapt vastly and fish eyes just fixed focus like plastic camera and dog eyes are color blind.

Human eyes are stereoscopic (can suspect the distance from sight), using comparison software can compare the parallax distance and this technology still don’t imitate by human equipment.

Monday, September 4, 2017

The Retina

Retina is a delicate servos membrane, upon the surface of which the images of external objects are received. Its outer surface is in contact which the choroid; its inner with the vitreous body. Behind it is continuous with the optic nerve; it is gradually diminishes in thickness from behind forward; and, in front, extends nearly as far as the ciliary body, where it appears to terminate is a jagged margin, the ora scrrata. Here the nervous tissues of the retina end, a thin prolongation of the membrane extends forward over the back of the ciliary processes and iris, forming the parts ciliaris retinae and parts iridiae retina, already referred to. This forward prolongation consists of the pigmentary layer of the retina together with a stratum of columnar epithelium.

The retina is soft, semi transparent, and of a purple tint in the fresh state, owing to the presence of a coloring material named rhodopsin or visual purple; but it soon becomes eluded, opaque and bleached when exposed to sunlight. Exactly in the center of the posterior park of the retina, corresponding to the axis of the eye, and at a point in the fresh state, owing to the presence of a coloring material named rhodopsin or visual purple; but it soon becomes clouded, opaque and bleached when exposed to sunlight. Exactly in the center of the posterior part of the retina, corresponding to the exist of the eye, and at a point in which the sense of vision is most perfect is an oval yellowish spot, called, after its discover, the yellow spot or macula lutea of Sommering , having a central depression, the fovea centralis.

The retina in the situation of the fovea centralis is exceedingly thin, and the dark color of the choroid is distinetly seen through it; so that it presents more the appearance of a foramen, and hence the name “foramen of Sommering” at first given to it. It exist only in man, the quadrumana and some suarian reptiles. About one-eight of an inch to the inner side of the yellow spot is the point of entrance of the optic nerve (porus opticus); here the nervous substance is slightly raised so as to form an eminence (colliculus nervi optivi); the arteria centralis retinae pierce its centre. That is the only part of the surface of the retina from which the power of vision is absent, and is termed the “blind spot.”

If the membrane damage than our eyes need use an aid tools like glass or contact lense, right now people don't need use this glass if use current technology by laser surgery LASIK.