Vision Disorders - Revision history

ChristopherBabson: VisionDisorders moved to Vision Disorders: FixName

2007-11-30T23:15:48Z

VisionDisorders moved to Vision Disorders: FixName

ChristopherBabson at 23:15, 30 November 2007

2007-11-30T23:15:39Z

ChristopherBabson at 23:15, 30 November 2007

2007-11-30T23:15:17Z

Asma Khan at 11:19, 16 July 2007

2007-07-16T11:19:13Z

Asma Khan at 11:01, 16 July 2007

2007-07-16T11:01:54Z

Asma Khan at 11:00, 16 July 2007

2007-07-16T11:00:54Z

Asma Khan at 10:55, 16 July 2007

2007-07-16T10:55:28Z

Asma Khan at 09:05, 16 July 2007

2007-07-16T09:05:34Z

Asma Khan at 08:50, 16 July 2007

2007-07-16T08:50:50Z

202.38.48.177: New page: DESCRIPTION Light that strikes the eyeball first passes through the cornea. The cornea is the tough, transparent covering at the front of the eye. It is shaped like a dome, with the top o...

2007-07-16T08:12:45Z

New page: DESCRIPTION Light that strikes the eyeball first passes through the cornea. The cornea is the tough, transparent covering at the front of the eye. It is shaped like a dome, with the top o...

New page

DESCRIPTION

Light that strikes the eyeball first passes through the cornea. The cornea is the tough, transparent covering at the front of the eye. It is shaped like a dome, with the top of the dome facing outward. Light then passes through the lens. The lens is located just inside the eyeball, behind the cornea. The lens has a double-convex shape. That is, it bulges outward in the middle.

The cornea and lens bend light as light waves pass through them. This process is known as refraction. In a normal eye, the light waves are brought to focus on the retina. The retina is a thin membrane at the back of the eye. Light waves cause chemical changes in the retina. These chemical changes set off a signal that passes through the optic nerve to the brain. The brain reads that signal as a visual image.

Muscles in the front of the eye can change the shape of the lens. These muscles adjust the lens shape to see objects close at hand or far away. This process is known as accommodation.

Visual disorders develop when the cornea and/or the lens do not properly focus light waves. The light waves do not come to a focus (that is, they do not all reach the same point) on the retina. They may come to a focus in front of the retina or behind the retina.

When light waves come to a focus in front of the retina, the person has myopia, or nearsightedness. People who are nearsighted can see objects close at hand, but they cannot see objects far away clearly. When light waves come to a focus behind the retina, the person has hyperopia, or farsightedness. People who are farsighted (hyperopic) can see objects far away but cannot clearly see objects close at hand.

In healthy eyes the cornea has a smooth, regular shape. Some people have corneas with an ellipsoidal shape, like a football or a squashed baseball. Such corneas scatter light waves across the retina, causing objects to appear as blurred images. This condition is called astigmatism.

@@ Line 26: / Line 26: @@
 Photorefractive Keratectomy, or PRK, is a type of laser eye surgery for people who suffer from nearsightedness [[myopia]], farsightedness(hyperopia) or astigmatism. It is similar to [[LASIK]]in that it involves using an Excimer laser to reshape the [[cornea]] to minimize or eliminate your dependence on eyeglasses or contact lenses.It is different in that unlike [[LASIK]] the eye surgeon doesn't need to use a [[microkeratome]] to make a flap, but instead is able to apply the laser directly to the surface of the cornea to achieve the desired vision correction effect. PRK is better suited for people with thin corneas or certain other corneal abnormalities where using a [[microkeratome]] might not be the best choice. Also it may be preferred for those in the United States military where PRK is the approved procedure for those in active combat and certain other positions. PRK has been approved by the FDA for myopia since 1995 and for hyperopia since 1998 and enjoys an excellent safety profile. Since it does not use a microkeratome, there is no risk of flap complications. In PRK to correct myopia, the steep [[cornea]] is made flatter by removing tissue from the center of the [[cornea]]. To correct hyperopia, the flat [[cornea]] is made steeper by removing tissue from the outer edges of the cornea. To correct [[astigmatism]], the [[cornea]] is transformed into a more spherical shape.
 [[Category:LASIK]]
 [[Category:LASIK Information]]
 [[Category:LASIK Terminology]]

← Older revision		Revision as of 23:15, 30 November 2007
Line 27:		Line 27:


−	[[Category:~~LASIKTerm~~]]	+	[[Category:LASIK]]
		+	[[Category:LASIK Information]]
		+	[[Category:LASIK Terminology]]

← Older revision		Revision as of 11:19, 16 July 2007
Line 26:		Line 26:
	Photorefractive Keratectomy, or PRK, is a type of laser eye surgery for people who suffer from nearsightedness [[myopia]], farsightedness(hyperopia) or astigmatism. It is similar to [[LASIK]]in that it involves using an Excimer laser to reshape the [[cornea]] to minimize or eliminate your dependence on eyeglasses or contact lenses.It is different in that unlike [[LASIK]] the eye surgeon doesn't need to use a [[microkeratome]] to make a flap, but instead is able to apply the laser directly to the surface of the cornea to achieve the desired vision correction effect. PRK is better suited for people with thin corneas or certain other corneal abnormalities where using a [[microkeratome]] might not be the best choice. Also it may be preferred for those in the United States military where PRK is the approved procedure for those in active combat and certain other positions. PRK has been approved by the FDA for myopia since 1995 and for hyperopia since 1998 and enjoys an excellent safety profile. Since it does not use a microkeratome, there is no risk of flap complications. In PRK to correct myopia, the steep [[cornea]] is made flatter by removing tissue from the center of the [[cornea]]. To correct hyperopia, the flat [[cornea]] is made steeper by removing tissue from the outer edges of the cornea. To correct [[astigmatism]], the [[cornea]] is transformed into a more spherical shape.		Photorefractive Keratectomy, or PRK, is a type of laser eye surgery for people who suffer from nearsightedness [[myopia]], farsightedness(hyperopia) or astigmatism. It is similar to [[LASIK]]in that it involves using an Excimer laser to reshape the [[cornea]] to minimize or eliminate your dependence on eyeglasses or contact lenses.It is different in that unlike [[LASIK]] the eye surgeon doesn't need to use a [[microkeratome]] to make a flap, but instead is able to apply the laser directly to the surface of the cornea to achieve the desired vision correction effect. PRK is better suited for people with thin corneas or certain other corneal abnormalities where using a [[microkeratome]] might not be the best choice. Also it may be preferred for those in the United States military where PRK is the approved procedure for those in active combat and certain other positions. PRK has been approved by the FDA for myopia since 1995 and for hyperopia since 1998 and enjoys an excellent safety profile. Since it does not use a microkeratome, there is no risk of flap complications. In PRK to correct myopia, the steep [[cornea]] is made flatter by removing tissue from the center of the [[cornea]]. To correct hyperopia, the flat [[cornea]] is made steeper by removing tissue from the outer edges of the cornea. To correct [[astigmatism]], the [[cornea]] is transformed into a more spherical shape.

−	~~==Process of Photorefractive Keratectomy==~~
−
−	Photorefractive Keratectomy involves, much like [[LASIK]], the reshaping of the [[cornea]]. Unlike [[LASIK]] which involves removing the inner tissue of the [[cornea]], [[PRK]] applies laser energy to change the surface of the [[cornea]]. Before surgery you will need to have a careful review of your health and eye history. Then you will need to have a refraction to measure your actual prescription. This will need to be performed with eye drops; in order to get the best measurements. The shape of the surface of your eyes will be mapped using an instrument called a corneal topographer. Finally the thickness of your cornea will be measured using an instrument called a [[Pachymeter]].
−
−	On your day of surgery, a technician will clean the area around your eyes with a hygienic but gentle cleansing pad. The technician will place a series of drops into your eyes in order to get them ready for your treatment. Some of these drops, antibiotic drops, will prevent germs from entering your eye and therefore help to prevent any possibility of infection. Other drops will be placed in your eyes to lightly numb the cornea so that you are comfortable during your treatment. After you recline on the bed-like chair under the laser, an eyelid holder called a speculum, is gently placed between your eyelids to remind you not to blink. Next the epithelium, a thin, protective layer that covers the cornea, is removed. Since you have had numbing drops placed in your eyes, this will not be uncomfortable, but will feel like a slight pressure around your eyes. The surgeon will instruct you to look at a small light during your procedure. Don't worry if you cannot stay perfectly steady-just do your best. Today's laser technology uses a tracking system which will actually follow your eye movements if you can hold pretty still during your procedure. To correct nearsightedness, farsightedness or astigmatism, your surgeon will use an [[Excimer laser]].
−
−	~~==Eligibility==~~
−	People are best suited for Photorefractive Keratectomy are people with moderate levels of myopia or hyperopia who have corneal abnormalities that make them not best suited for [[LASIK]]. However PRK may also be used for people with high prescription levels and for active military personnel.
−	*Better for thin corneas
−	*Good for low to high levels of myopia,hyperopia and/or astigmatism
−	*Good for people in military service
−
−	~~==Disadvantages==~~
−	*Longer healing time
−	*Longer time for results
−
−	Photorefractive Keratectomy is a less used procedure due to [[LASIK]]. However, it is still the procedure used when [[LASIK]] is not the best choice due to eye irregularities. As with all laser surgery, there is always a risk and side effects like light sensitivity and halos may not go away. It is important to talk with your eye care doctor about the risks in your specific case.

	[[Category:LASIKTerm]]		[[Category:LASIKTerm]]

@@ Line 28: / Line 28: @@
 ==Process of Photorefractive Keratectomy==
-Photorefractive Keratectomy involves, much like [[LASIK]], the reshaping of the [[cornea]]. Unlike [[LASIK]] which involves removing the inner tissue of the [[cornea]], [[PRK]] applies laser energy to change the surface of the [[cornea]]. Before surgery you will need to have a careful review of your health and eye history. Then you will need to have a refraction to measure your actual prescription. This will need to be performed with eye drops; in order to get the best measurements. The shape of the surface of your eyes will be mapped using an instrument called a corneal topographer. Finally the thickness of your cornea will be measured using an instrument called a [[pachymeter]].
+Photorefractive Keratectomy involves, much like [[LASIK]], the reshaping of the [[cornea]]. Unlike [[LASIK]] which involves removing the inner tissue of the [[cornea]], [[PRK]] applies laser energy to change the surface of the [[cornea]]. Before surgery you will need to have a careful review of your health and eye history. Then you will need to have a refraction to measure your actual prescription. This will need to be performed with eye drops; in order to get the best measurements. The shape of the surface of your eyes will be mapped using an instrument called a corneal topographer. Finally the thickness of your cornea will be measured using an instrument called a [[Pachymeter]].
 On your day of surgery, a technician will clean the area around your eyes with a hygienic but gentle cleansing pad. The technician will place a series of drops into your eyes in order to get them ready for your treatment. Some of these drops, antibiotic drops, will prevent germs from entering your eye and therefore help to prevent any possibility of infection. Other drops will be placed in your eyes to lightly numb the cornea so that you are comfortable during your treatment. After you recline on the bed-like chair under the laser, an eyelid holder called a speculum, is gently placed between your eyelids to remind you not to blink. Next the epithelium, a thin, protective layer that covers the cornea, is removed. Since you have had numbing drops placed in your eyes, this will not be uncomfortable, but will feel like a slight pressure around your eyes. The surgeon will instruct you to look at a small light during your procedure. Don't worry if you cannot stay perfectly steady-just do your best. Today's laser technology uses a tracking system which will actually follow your eye movements if you can hold pretty still during your procedure. To correct nearsightedness, farsightedness or astigmatism, your surgeon will use an [[Excimer laser]].

@@ Line 1: / Line 1: @@
 ==How the Eye Works?==
-Light that strikes the eyeball first passes through the cornea. The cornea is the tough, transparent covering at the front of the eye. It is shaped like a dome.facing outward. Light then passes through the lens. The lens is located just inside the eyeball, behind the cornea. The lens has a double-convex shape. The cornea and lens bend light as light waves pass through them. This process is known as [[Refraction]]. In a normal eye, the light waves are brought to focus on the retina. The retina is a thin membrane at the back of the eye. Light waves cause chemical changes in the retina. These chemical changes set off a signal that passes through the optic nerve to the brain. The brain reads that signal as a 'visual image'.Muscles in the front of the eye can change the shape of the lens. These muscles adjust the lens shape to see objects close at hand or far away. This process is known as 'accommodation'.
+Light that strikes the eyeball first passes through the [[cornea]]. The [[cornea]] is the tough, transparent covering at the front of the eye. It is shaped like a dome.facing outward. Light then passes through the lens. The lens is located just inside the eyeball, behind the [[cornea]]. The lens has a double-convex shape. The cornea and lens bend light as light waves pass through them. This process is known as [[Refraction]]. In a normal eye, the light waves are brought to focus on the retina. The retina is a thin membrane at the back of the eye. Light waves cause chemical changes in the retina. These chemical changes set off a signal that passes through the optic nerve to the brain. The brain reads that signal as a 'visual image'.Muscles in the front of the eye can change the shape of the lens. These muscles adjust the lens shape to see objects close at hand or far away. This process is known as 'accommodation'.
 ==How  Visual Disorders  occur?==
-Visual disorders develop when the cornea and/or the lens do not properly focus light waves. The light waves do not come to a focus (that is, they do not all reach the same point) on the retina. They may come to a focus in front of the retina or behind the retina.The primary symptom of any vision disorder is the inability to see objects clearly. Objects near by or far away will seem blurry to a person with farsightedness or nearsightedness. Objects at almost any distance will seem blurry to a person with astigmatism.
+Visual disorders develop when the [[cornea]] and/or the lens do not properly focus light waves. The light waves do not come to a focus (that is, they do not all reach the same point) on the retina. They may come to a focus in front of the retina or behind the retina.The primary symptom of any vision disorder is the inability to see objects clearly. Objects near by or far away will seem blurry to a person with farsightedness or nearsightedness. Objects at almost any distance will seem blurry to a person with astigmatism.
 Most vision disorders are thought to be inherited. That is, the disorders are passed down from one generation to the next. Most babies are born slightly hyperopic. However, this pattern changes as they grow older. In most cases, children develop normal vision. They may, however, become more hyperopic, or they may develop myopia.
 Some eyecare specialists argue that vision disorders may be caused by a number of factors in the environment, such as work conditions, stress, and eye strain, can contribute to the development of vision disorders.
-The development of astigmatism has been attributed to a number of factors. For example, people with allergies often rub their eyes repeatedly. This constant rubbing may cause damage to the cornea. Diabetes (see diabetes mellitus entry) is also known to change the shape of the cornea over time.
+The development of astigmatism has been attributed to a number of factors. For example, people with allergies often rub their eyes repeatedly. This constant rubbing may cause damage to the cornea. Diabetes (see diabetes mellitus entry) is also known to change the shape of the [[cornea]] over time.
 ==Symptoms==
@@ Line 21: / Line 21: @@
 The results of an eye chart test are usually indicated by a pair of numbers, such as 20/50. These numbers show how well a person can see an object compared to a person with normal eyesight. A person with 20/50 vision can see at 20 feet from an eye chart what a person with normal vision can see at 50 feet from the chart.There are a number of lenses through which the patient is supposed to look at the eye chart.The lens are changed until the patient is able to see the letters on the chart clearly. The degree of error in the patient's eye is determined by the lens needed to produce perfect vision. This degree of error is measured in units called diopters (abbreviated: D). The prescription a doctor writes for glasses will indicate the shape of the lens (the diopter measurements) needed to provide perfect vision.
-A simple test for astigmatism consists of a dial containing lines that radiate outward from the center. A person with astigmatism will be able to see some lines more clearly than other lines.
+A simple test for [[astigmatism]] consists of a dial containing lines that radiate outward from the center. A person with [[astigmatism]] will be able to see some lines more clearly than other lines.
 Doctors may also use direct tests on the eye. For example, a device known as a corneal topographer can be used to measure the shape of the cornea and determine whether the shape is correct or not. Doctors can also shine a light directly at the retina in a person's eye to look for any damage.
-Photorefractive Keratectomy, or PRK, is a type of laser eye surgery for people who suffer from nearsightedness (myopia), farsightedness(hyperopia) or astigmatism. It is similar to [[LASIK]]in that it involves using an Excimer laser to reshape the cornea to minimize or eliminate your dependence on eyeglasses or contact lenses.It is different in that unlike [[LASIK]] the eye surgeon doesn't need to use a microkeratome to make a flap, but instead is able to apply the laser directly to the surface of the cornea to achieve the desired vision correction effect. PRK is better suited for people with thin corneas or certain other corneal abnormalities where using a microkeratome might not be the best choice. Also it may be preferred for those in the United States military where PRK is the approved procedure for those in active combat and certain other positions. PRK has been approved by the FDA for myopia since 1995 and for hyperopia since 1998 and enjoys an excellent safety profile. Since it does not use a microkeratome, there is no risk of flap complications. In PRK to correct myopia, the steep cornea is made flatter by removing tissue from the center of the cornea. To correct hyperopia, the flat cornea is made steeper by removing tissue from the outer edges of the cornea. To correct astigmatism, the cornea is transformed into a more spherical shape.
+Photorefractive Keratectomy, or PRK, is a type of laser eye surgery for people who suffer from nearsightedness [[myopia]], farsightedness(hyperopia) or astigmatism. It is similar to [[LASIK]]in that it involves using an Excimer laser to reshape the [[cornea]] to minimize or eliminate your dependence on eyeglasses or contact lenses.It is different in that unlike [[LASIK]] the eye surgeon doesn't need to use a [[microkeratome]] to make a flap, but instead is able to apply the laser directly to the surface of the cornea to achieve the desired vision correction effect. PRK is better suited for people with thin corneas or certain other corneal abnormalities where using a [[microkeratome]] might not be the best choice. Also it may be preferred for those in the United States military where PRK is the approved procedure for those in active combat and certain other positions. PRK has been approved by the FDA for myopia since 1995 and for hyperopia since 1998 and enjoys an excellent safety profile. Since it does not use a microkeratome, there is no risk of flap complications. In PRK to correct myopia, the steep [[cornea]] is made flatter by removing tissue from the center of the [[cornea]]. To correct hyperopia, the flat [[cornea]] is made steeper by removing tissue from the outer edges of the cornea. To correct [[astigmatism]], the [[cornea]] is transformed into a more spherical shape.
 ==Process of Photorefractive Keratectomy==
-Photorefractive Keratectomy involves, much like [[LASIK]], the reshaping of the cornea. Unlike [[LASIK]] which involves removing the inner tissue of the cornea, PRK applies laser energy to change the surface of the cornea. Before surgery you will need to have a careful review of your health and eye history. Then you will need to have a refraction to measure your actual prescription. This will need to be performed with eye drops; in order to get the best measurements. The shape of the surface of your eyes will be mapped using an instrument called a corneal topographer. Finally the thickness of your cornea will be measured using an instrument called a pachymeter.
+Photorefractive Keratectomy involves, much like [[LASIK]], the reshaping of the [[cornea]]. Unlike [[LASIK]] which involves removing the inner tissue of the [[cornea]], [[PRK]] applies laser energy to change the surface of the [[cornea]]. Before surgery you will need to have a careful review of your health and eye history. Then you will need to have a refraction to measure your actual prescription. This will need to be performed with eye drops; in order to get the best measurements. The shape of the surface of your eyes will be mapped using an instrument called a corneal topographer. Finally the thickness of your cornea will be measured using an instrument called a [[pachymeter]].
-On your day of surgery, a technician will clean the area around your eyes with a hygienic but gentle cleansing pad. The technician will place a series of drops into your eyes in order to get them ready for your treatment. Some of these drops, antibiotic drops, will prevent germs from entering your eye and therefore help to prevent any possibility of infection. Other drops will be placed in your eyes to lightly numb the cornea so that you are comfortable during your treatment. After you recline on the bed-like chair under the laser, an eyelid holder called a speculum, is gently placed between your eyelids to remind you not to blink. Next the epithelium, a thin, protective layer that covers the cornea, is removed. Since you have had numbing drops placed in your eyes, this will not be uncomfortable, but will feel like a slight pressure around your eyes. The surgeon will instruct you to look at a small light during your procedure. Don't worry if you cannot stay perfectly steady-just do your best. Today's laser technology uses a tracking system which will actually follow your eye movements if you can hold pretty still during your procedure. To correct nearsightedness, farsightedness or astigmatism, your surgeon will use an Excimer laser.
+On your day of surgery, a technician will clean the area around your eyes with a hygienic but gentle cleansing pad. The technician will place a series of drops into your eyes in order to get them ready for your treatment. Some of these drops, antibiotic drops, will prevent germs from entering your eye and therefore help to prevent any possibility of infection. Other drops will be placed in your eyes to lightly numb the cornea so that you are comfortable during your treatment. After you recline on the bed-like chair under the laser, an eyelid holder called a speculum, is gently placed between your eyelids to remind you not to blink. Next the epithelium, a thin, protective layer that covers the cornea, is removed. Since you have had numbing drops placed in your eyes, this will not be uncomfortable, but will feel like a slight pressure around your eyes. The surgeon will instruct you to look at a small light during your procedure. Don't worry if you cannot stay perfectly steady-just do your best. Today's laser technology uses a tracking system which will actually follow your eye movements if you can hold pretty still during your procedure. To correct nearsightedness, farsightedness or astigmatism, your surgeon will use an [[Excimer laser]].
 ==Eligibility==

← Older revision	Revision as of 23:15, 30 November 2007
(No difference)

← Older revision		Revision as of 10:55, 16 July 2007
Line 24:		Line 24:

	Doctors may also use direct tests on the eye. For example, a device known as a corneal topographer can be used to measure the shape of the cornea and determine whether the shape is correct or not. Doctors can also shine a light directly at the retina in a person's eye to look for any damage.		Doctors may also use direct tests on the eye. For example, a device known as a corneal topographer can be used to measure the shape of the cornea and determine whether the shape is correct or not. Doctors can also shine a light directly at the retina in a person's eye to look for any damage.
		+	Photorefractive Keratectomy, or PRK, is a type of laser eye surgery for people who suffer from nearsightedness (myopia), farsightedness(hyperopia) or astigmatism. It is similar to [[LASIK]]in that it involves using an Excimer laser to reshape the cornea to minimize or eliminate your dependence on eyeglasses or contact lenses.It is different in that unlike [[LASIK]] the eye surgeon doesn't need to use a microkeratome to make a flap, but instead is able to apply the laser directly to the surface of the cornea to achieve the desired vision correction effect. PRK is better suited for people with thin corneas or certain other corneal abnormalities where using a microkeratome might not be the best choice. Also it may be preferred for those in the United States military where PRK is the approved procedure for those in active combat and certain other positions. PRK has been approved by the FDA for myopia since 1995 and for hyperopia since 1998 and enjoys an excellent safety profile. Since it does not use a microkeratome, there is no risk of flap complications. In PRK to correct myopia, the steep cornea is made flatter by removing tissue from the center of the cornea. To correct hyperopia, the flat cornea is made steeper by removing tissue from the outer edges of the cornea. To correct astigmatism, the cornea is transformed into a more spherical shape.
		+
		+	==Process of Photorefractive Keratectomy==
		+
		+	Photorefractive Keratectomy involves, much like [[LASIK]], the reshaping of the cornea. Unlike [[LASIK]] which involves removing the inner tissue of the cornea, PRK applies laser energy to change the surface of the cornea. Before surgery you will need to have a careful review of your health and eye history. Then you will need to have a refraction to measure your actual prescription. This will need to be performed with eye drops; in order to get the best measurements. The shape of the surface of your eyes will be mapped using an instrument called a corneal topographer. Finally the thickness of your cornea will be measured using an instrument called a pachymeter.
		+
		+	On your day of surgery, a technician will clean the area around your eyes with a hygienic but gentle cleansing pad. The technician will place a series of drops into your eyes in order to get them ready for your treatment. Some of these drops, antibiotic drops, will prevent germs from entering your eye and therefore help to prevent any possibility of infection. Other drops will be placed in your eyes to lightly numb the cornea so that you are comfortable during your treatment. After you recline on the bed-like chair under the laser, an eyelid holder called a speculum, is gently placed between your eyelids to remind you not to blink. Next the epithelium, a thin, protective layer that covers the cornea, is removed. Since you have had numbing drops placed in your eyes, this will not be uncomfortable, but will feel like a slight pressure around your eyes. The surgeon will instruct you to look at a small light during your procedure. Don't worry if you cannot stay perfectly steady-just do your best. Today's laser technology uses a tracking system which will actually follow your eye movements if you can hold pretty still during your procedure. To correct nearsightedness, farsightedness or astigmatism, your surgeon will use an Excimer laser.
		+
		+	==Eligibility==
		+	People are best suited for Photorefractive Keratectomy are people with moderate levels of myopia or hyperopia who have corneal abnormalities that make them not best suited for [[LASIK]]. However PRK may also be used for people with high prescription levels and for active military personnel.
		+	*Better for thin corneas
		+	*Good for low to high levels of myopia,hyperopia and/or astigmatism
		+	*Good for people in military service
		+
		+	==Disadvantages==
		+	*Longer healing time
		+	*Longer time for results
		+
		+	Photorefractive Keratectomy is a less used procedure due to [[LASIK]]. However, it is still the procedure used when [[LASIK]] is not the best choice due to eye irregularities. As with all laser surgery, there is always a risk and side effects like light sensitivity and halos may not go away. It is important to talk with your eye care doctor about the risks in your specific case.
		+
		+	[[Category:LASIKTerm]]

@@ Line 14: / Line 14: @@
 ==DIAGNOSIS==
-Vision disorders are sometimes difficult to diagnose. They have often grown up seeing the world slightly out of focus and their view of objects may seem perfectly normal.
+There are three major types of visual disorders:[[Myopia]] or near-sightedness,[[Hyperopia]] or far-sightedness and [[Astigmatism]] ,a situation which causes the eye to form a blurred vision of an object.When light waves come to a focus in front of the retina, the person has myopia, or nearsightedness. People who are nearsighted can see objects close at hand, but they cannot see objects far away clearly. When light waves come to a focus behind the retina, the person has hyperopia, or farsightedness. People who are farsighted (hyperopic) can see objects far away but cannot clearly see objects close at hand.In healthy eyes the cornea has a smooth, regular shape. Some people have corneas with an ellipsoidal shape, like a football or a squashed baseball. Such corneas scatter light waves across the retina, causing objects to appear as blurred images. This condition is called astigmatism.
-As a result, many vision problems are detected by others. For example, school teachers may realize that a pupil is unable to read the blackboard. Or a parent may notice that a child is constantly squinting while trying to read. In such cases, the individual is referred to an eye specialist for examination.
+Vision disorders are sometimes difficult to diagnose. They have often grown up seeing the world slightly out of focus and their view of objects may seem perfectly normal.As a result, many vision problems are detected by others. For example, school teachers may realize that a pupil is unable to read the blackboard. Or a parent may notice that a child is constantly squinting while trying to read. In such cases, the individual is referred to an eye specialist for examination.
 Astigmatism is a condition in which light from a single point fails to focus on a single point of the retina. The condition causes the patient to see a blurred image.
-Astigmatism is a condition in which light from a single point fails to focus on a single point of the retina. The condition causes the patient to see a blurred image. (Reproduced by permission of Electronic Illustrators Group)
+The most common tests involve the use of the familiar eye chart. The eye chart contains rows of letters of decreasing size going from top to bottom. The patient is asked to read each row on the chart. The last row the patient is able to read tells how accurate is his or her vision.
-Astigmatism is a condition in which light from a single point fails to focus on a single point of the retina. The condition causes the patient to see a blurred image. (Reproduced by permission of
+The results of an eye chart test are usually indicated by a pair of numbers, such as 20/50. These numbers show how well a person can see an object compared to a person with normal eyesight. A person with 20/50 vision can see at 20 feet from an eye chart what a person with normal vision can see at 50 feet from the chart.There are a number of lenses through which the patient is supposed to look at the eye chart.The lens are changed until the patient is able to see the letters on the chart clearly. The degree of error in the patient's eye is determined by the lens needed to produce perfect vision. This degree of error is measured in units called diopters (abbreviated: D). The prescription a doctor writes for glasses will indicate the shape of the lens (the diopter measurements) needed to provide perfect vision.
 A simple test for astigmatism consists of a dial containing lines that radiate outward from the center. A person with astigmatism will be able to see some lines more clearly than other lines.
 Doctors may also use direct tests on the eye. For example, a device known as a corneal topographer can be used to measure the shape of the cornea and determine whether the shape is correct or not. Doctors can also shine a light directly at the retina in a person's eye to look for any damage.