Archive for the ‘Eye Test’ Category

Lasik Effect on Cornea

Lasik is a commonly used surgical method for correcting many a refractive errors. Through Lasik The Corneal tissue shape is altered so as to correct the vision impairment problems. Lasik is much sough after as the surgical procedure in itself does not take too long and the healing process is also fast. The pain involved in the procedure is also minimal. It is a surgery which involves very high precision and the carving of the corneal tissue is very fine. Whatever the kind of vision problem, altering the corneal shape is a practical solution. In case of abnormality in the corneal tissue it is possible that some complications may arise during Lasik. Lasik is advancing at a very fast pace and is a good surgical option but there are also certain complications that may arise.

A corneal infection is a possible complication of Lasik. Corneal infection because of a Lasik surgery is not a major problem. Corneal infection is a more common problem in other PRK surgeries and less so after Lasik. Although the corneal infection after Lasik does not have any long term impact on the eye, the only problem is the slight discomfort that the patient would face. The healing process also slows down with such a complication.

Corneal Haze is also another potential problem that may occur after Lasik. It is not unusual for corneal haze to develop after Lasik as it is a potential problem after any sort of refractive surgery. The corneal haze does not affect the final vision of the patient. This problem can only be seen by the ophthalmologist under a microscope. But there have been instances where the corneal haze has shown to affect the final vision of the patient. If this condition is detected then the patient would need a second surgery to correct the problem. A point to be noted is that the chances of ending up with corneal haze of excessive nature are higher in PRK surgeries than in a Lasik surgery.

Another effect of Lasik on the cornea is the Halo effect. This becomes a problem when bright light hits the eye. A faded image is seen around the actual image. This happens due to the image being produced by the untreated portion of the peripheral cornea. A further potential problem is if the corneal flap is distorted in the healing process; then this can affect the shape of the cornea. There are many a problems that can affect the cornea in a Lasik but most of them can be corrected and there is no reason to be alarmed. Lasik is a very much preferred solution for eye problems.

Categories: Eye Test

Keystone Eye Care Group

Eye Care & Vision Problems : What Is Done in an Eye Exam?

Snellen Eye Chart

All of us would be familiar with the Snellen eye chart. It is the chart used to test the clarity of your vision when you visit an eye specialist. The chart gets its name from Herman Snellen, a Dutch ophthalmologist, who was instrumental in preparing the chart way back in 1862.

The chart has eleven lines in all and the first line has just one alphabet which is very large in size. In the lines below the number of alphabets increases and at the same time the size of the alphabets decreases. The test is taken in a way where one eye is covered and the person is told to read out the alphabets. The visual acuity is determined depending upon the smallest alphabet that the person is able to read. The other eye is tested in the same fashion. The alphabets shown on the Snellen Eye Chart are known as optotypes. The letters are not printed in an ordinary manner but the length, width and height do have some geometrical implications.

The customary Snellen chart has only the following 10 alphabets C, D, E, F, L, N, O, P, T, Z. The chart that is wall mounted is inexpensive and is generally used for a preliminary examination of the eye. The Visual acuity is determined by a formula which is:

Distance from where the test is conducted/ distance where the smallest optotype recognized subtends at an angle of 5 arcminutes. The chart is placed at a standard distance of 20 feet in most countries for the test. The chart also has certain specifications, it should be made on non-reflective material, it should have a matte finish, should be made of durable plastic and also the standard size is 22”*11”.

The Snellen eye chart also has its variations i.e. for illiterate persons and for young children who do not know how to read. For the illiterate, the chart has the alphabet E written in various directions and the ones for young children have symbols on it. The Snellen eye chart has also been a subject for a lot of criticism. Many are of the opinion that patients might memorize the chart and this would end up in a wrong result. Also after testing one eye they may be able to memorize it because of which the other eye may seem perfect. But even with all the criticism the chart has been in use all these years. Even with so much progress made in the field of medicine, the Snellen Eye Chart is the primary test one has to go through which speaks volumes about it.

Eye Test

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