Vision: Most Popular Articles
These articles are the most popular over the last month.
Eye Styes
A stye is a common eye problem. Learn about the causes and treatment of eye styes.
A stye is a common eye problem. Learn about the causes and treatment of eye styes.
Red Eye
Red, bloodshot eyes can be caused by many things. Here are the top 10 causes of red eye.
Red, bloodshot eyes can be caused by many things. Here are the top 10 causes of red eye.
Eye Twitching
Eye twitching, or myokymia, is an involuntary eyelid muscle contraction. The exact cause of an eyelid twitch is not known. A twitch sometimes develops during times of increased stress.
Eye twitching, or myokymia, is an involuntary eyelid muscle contraction. The exact cause of an eyelid twitch is not known. A twitch sometimes develops during times of increased stress.
Eye Problems
Learn about common eye problems including itchy eyes, blurry vision, tired eyes, floaters and age-related conditions.
Learn about common eye problems including itchy eyes, blurry vision, tired eyes, floaters and age-related conditions.
Blepharitis
Blepharitis is a common condition affecting the eyelids. It is a common problem in both children and adults.
Blepharitis is a common condition affecting the eyelids. It is a common problem in both children and adults.
Red Eye Treatment
Learn ways to treat red eye.
Learn ways to treat red eye.
Stop Eye Twitching
Learn ways to control eye twitching.
Learn ways to control eye twitching.
Baby Eye Color
A baby's eye color is determined by the amount of pigment contained in the iris.
A baby's eye color is determined by the amount of pigment contained in the iris.
Conjunctivitis
Learn all about pink eye and ways to keep it from spreading.
Learn all about pink eye and ways to keep it from spreading.
Red Spot in Eye
Find out why you sometimes awaken to a red spot in your eye.
Find out why you sometimes awaken to a red spot in your eye.
Cost of Contacts
Several factors determine the overall cost of wearing contact lenses.
Several factors determine the overall cost of wearing contact lenses.
Avoid Eye Styes
If you are prone to styes, the following tips may help you avoid them.
If you are prone to styes, the following tips may help you avoid them.
Spots and Floaters
Eye spots and floaters are small particles in the fluid inside your eye.
Eye spots and floaters are small particles in the fluid inside your eye.
Red Eye Warning Symptoms
If you have red eye, look out for the following warning symptoms that may be serious.
If you have red eye, look out for the following warning symptoms that may be serious.
Pupils Stay Dilated?
After an eye examination, how long will my pupils remain dilated?
After an eye examination, how long will my pupils remain dilated?
Glaucoma
Glaucoma refers to a group of diseases that cause damage to the optic nerve. If left untreated, glaucoma may cause vision loss and blindness.
Glaucoma refers to a group of diseases that cause damage to the optic nerve. If left untreated, glaucoma may cause vision loss and blindness.
Choosing Eyeglasses
Choosing the right eyeglasses for your face. Determine the shape of your face and choose the most flattering frame styles.
Choosing the right eyeglasses for your face. Determine the shape of your face and choose the most flattering frame styles.
Astigmatism
Astigmatism, commonly mistaken as stigmatism, is a vision disorder that causes objects to be blurry, both at distance and at near.
Astigmatism, commonly mistaken as stigmatism, is a vision disorder that causes objects to be blurry, both at distance and at near.
Eye Drops With Contacts?
Can "get the red out" eye drops be used with contact lenses?
Can "get the red out" eye drops be used with contact lenses?
Dry Eye Syndrome
If you have scratchy, dry eyes, you may suffer from dry eye syndrome. Learn how to treat dry eye syndrome.
If you have scratchy, dry eyes, you may suffer from dry eye syndrome. Learn how to treat dry eye syndrome.
Eye Inflammation
It may sound like a condition caused by the sun's UV rays, but uveitis is actually an inflammation or swelling of the eye's uvea.
It may sound like a condition caused by the sun's UV rays, but uveitis is actually an inflammation or swelling of the eye's uvea.
What Is Monovision?
My eye doctor offered to fit me with monovision contact lenses. What is monovision?
My eye doctor offered to fit me with monovision contact lenses. What is monovision?
The Basics of Nearsightedness
Nearsightedness is a common vision problem. Nearsightedness causes distant objects to be blurry.
Nearsightedness is a common vision problem. Nearsightedness causes distant objects to be blurry.
Before You Get Contacts
Are you thinking of trying contacts? Learn the pros and cons of wearing contacts.
Are you thinking of trying contacts? Learn the pros and cons of wearing contacts.
Eye Examination Tests
A comprehensive eye exam includes several tests. Each test will help your eye doctor determine the overall health of your eyes.
A comprehensive eye exam includes several tests. Each test will help your eye doctor determine the overall health of your eyes.
Sun Protection
Learn how to protect your eyes from the sun. Exposure to UV radiation can harm your eyes and affect your vision.
Learn how to protect your eyes from the sun. Exposure to UV radiation can harm your eyes and affect your vision.
Dry Eye Symptoms
Dry eye, or dry eye syndrome, is a common eye condition that causes discomfort due to lack of moisture in the eyes. Below are the top seven signs and symptoms of dry eye.
Dry eye, or dry eye syndrome, is a common eye condition that causes discomfort due to lack of moisture in the eyes. Below are the top seven signs and symptoms of dry eye.
Eye Freckle
A choroidal nevus is simply a freckle inside the eye.
A choroidal nevus is simply a freckle inside the eye.
Newborn Vision
Your newborn baby gazes at you, but what does he really see?
Your newborn baby gazes at you, but what does he really see?
Eyeglass Prescriptions
Learn how to make sense of your eyeglass prescription.
Learn how to make sense of your eyeglass prescription.
PVD
Posterior vitreous detachment is a common condition in people over age 65.
Posterior vitreous detachment is a common condition in people over age 65.
Seeing Stars
"Seeing stars" may result from a sneeze, a deep cough, a blow to the head or low blood pressure.
"Seeing stars" may result from a sneeze, a deep cough, a blow to the head or low blood pressure.
Which Eye Is Dominant?
This quick test will determine eye dominance. Find your dominant eye.
This quick test will determine eye dominance. Find your dominant eye.
Corneal Ulcer
A corneal ulcer is an opening, sore or erosion in the cornea. If the cornea becomes inflamed due to infection or injury, an ulcer may develop. A corneal ulcer is a serious condition that must be treated promptly to avoid lasting vision problems.
A corneal ulcer is an opening, sore or erosion in the cornea. If the cornea becomes inflamed due to infection or injury, an ulcer may develop. A corneal ulcer is a serious condition that must be treated promptly to avoid lasting vision problems.
Lens Options
Eyeglass lenses can be made from several different materials. Find out which lens material is best for your next pair of frames.
Eyeglass lenses can be made from several different materials. Find out which lens material is best for your next pair of frames.
Hyphema
Hyphema refers to the presence of blood in the eye, usually caused by trauma to the eye.
Hyphema refers to the presence of blood in the eye, usually caused by trauma to the eye.
Snellen Eye Chart
A Snellen eye chart is the eye chart used by your eye doctor to check vision acuity.
A Snellen eye chart is the eye chart used by your eye doctor to check vision acuity.
Choosing Eye Doctors
Choosing among eye doctors is an important step toward taking care of your eyes and vision. Eye doctors will help to protect your precious sense of sight and help you to have the best vision possible. How do you Ophthalmologists, optometrists and opticians all provide eye care services. They are known as the three O's of eye care.
Choosing among eye doctors is an important step toward taking care of your eyes and vision. Eye doctors will help to protect your precious sense of sight and help you to have the best vision possible. How do you Ophthalmologists, optometrists and opticians all provide eye care services. They are known as the three O's of eye care.
Clean Glasses
Learn how to clean your eyeglasses the correct way to prolong the life of your eyeglasses and lenses.
Learn how to clean your eyeglasses the correct way to prolong the life of your eyeglasses and lenses.
How to Buy Eyeglasses
The following steps will help you find the perfect eyeglasses to fit your look and lifestyle.
The following steps will help you find the perfect eyeglasses to fit your look and lifestyle.
Lazy Eye
Lazy eye, or amblyopia, is an eye problem that sometimes occurs in chldren. Learn facts and treatment options for amblyopia.
Lazy eye, or amblyopia, is an eye problem that sometimes occurs in chldren. Learn facts and treatment options for amblyopia.
Dilation
Why do eye doctors dilate the eyes?
Why do eye doctors dilate the eyes?
Contact Lenses
Learn facts and tips about contact lenses. Find out if contact lenses are for you.
Learn facts and tips about contact lenses. Find out if contact lenses are for you.
What are computer glasses?
Do you need a pair of computer glasses? Learn about computer glasses and how they might relieve eyestrain caused by the computer.
Do you need a pair of computer glasses? Learn about computer glasses and how they might relieve eyestrain caused by the computer.
Habits for Good Eyesight
Having good eye sight greatly improves one's quality of life. Make a conscious effort to keep your eyes in their best condition by following these quick tips.
Having good eye sight greatly improves one's quality of life. Make a conscious effort to keep your eyes in their best condition by following these quick tips.
Cataracts Symptoms & Treatment
A cataract is a clouding of the eye's lens, which occurs with aging. The symptoms are sometime bothersome and require treatment
A cataract is a clouding of the eye's lens, which occurs with aging. The symptoms are sometime bothersome and require treatment
Proptosis
Proptosis is a forward displacement of the eye in the orbit, caused by swelling of the soft tissues or bones of the orbit.
Proptosis is a forward displacement of the eye in the orbit, caused by swelling of the soft tissues or bones of the orbit.
CVS
If you spend a lot of time each day in front of a computer, you are likely to experience symptoms of computer vision syndrome (CVS).
If you spend a lot of time each day in front of a computer, you are likely to experience symptoms of computer vision syndrome (CVS).
Annual Eye Exam
Your doctor urges you to have an eye exam every year. Is an annual eye exam really necessary?
Your doctor urges you to have an eye exam every year. Is an annual eye exam really necessary?
Basics of Farsightedness
Symptoms and treatment of farsightedness, or hyperopia.
Symptoms and treatment of farsightedness, or hyperopia.
20/20 Vision
The smallest line you can read on a chart is your visual acuity. Perfect visual acuity is written as 20/20.
The smallest line you can read on a chart is your visual acuity. Perfect visual acuity is written as 20/20.
Retinal Detachment
Retinal detachment is when the retina separates from the choroid. Retinal detachment is a true eye emergency.
Retinal detachment is when the retina separates from the choroid. Retinal detachment is a true eye emergency.
Foreign Object removal
Follow these tips if you have a foreign object in your eye.
Follow these tips if you have a foreign object in your eye.
Epidemic Keratoconjunctivitis
Learn about epidemic keraconjunctivitis, a highly contagious viral eye infection.
Learn about epidemic keraconjunctivitis, a highly contagious viral eye infection.
Eye Allergies
Red, itchy, watery eyes plague many people suffering from irritating eye allergies.
Red, itchy, watery eyes plague many people suffering from irritating eye allergies.
Sarcoidosis
Learn how sarcoidosis may affect your eyes.
Learn how sarcoidosis may affect your eyes.
Minimize Eye Infection
Properly caring for your lenses can prevent serious eye infections, some that could even cause blindness. Below are the top 10 ways for contact lens users to minimize the chance of developing an eye infection.
Properly caring for your lenses can prevent serious eye infections, some that could even cause blindness. Below are the top 10 ways for contact lens users to minimize the chance of developing an eye infection.
Myokymia
An involuntary eyelid muscle contraction, typically involving the lower eyelid, less often the upper eyelid.
An involuntary eyelid muscle contraction, typically involving the lower eyelid, less often the upper eyelid.
Lens Options for Presbyopia
Several lens options exist for correcting presbyopia, or the blurring of our vision that happens as we age.
Several lens options exist for correcting presbyopia, or the blurring of our vision that happens as we age.
Presbyopia
Presbyopia is defined as the loss of the eye's ability to change focus to see near objects. Presbyopia, or "short-armed syndrome", decreases our ability to focus on near objects. Presbyopia is a vision disorder that develops as we age.
Presbyopia is defined as the loss of the eye's ability to change focus to see near objects. Presbyopia, or "short-armed syndrome", decreases our ability to focus on near objects. Presbyopia is a vision disorder that develops as we age.
Newborns and Crossed Eyes
Crossed eyes are normal in newborn infants, as the entire visual system is underdeveloped.
Crossed eyes are normal in newborn infants, as the entire visual system is underdeveloped.
Ptosis
Droopy eyelids is known as ptosis.
Droopy eyelids is known as ptosis.
Ophthalmic Migraine Causes
What causes an ophthalmic migraine?
What causes an ophthalmic migraine?
Vision Development
Learn how a child's vision develops throughout the first year of life.
Learn how a child's vision develops throughout the first year of life.
Signs Your Child Needs Glasses
Many children have undetected vision problems. Parents and teachers must watch for obvious signs that a child might need glasses.
Many children have undetected vision problems. Parents and teachers must watch for obvious signs that a child might need glasses.
Blocked Tear Duct Treatment
If a blocked tear duct is discovered early enough, treatment is usually simple, and infection can usually be avoided.
If a blocked tear duct is discovered early enough, treatment is usually simple, and infection can usually be avoided.
Graves' Disease
Graves' disease is the most common form of hyperthyroidism.
Graves' disease is the most common form of hyperthyroidism.
Color Blindness
Color blind people have problems distinguishing between certain colors, usually red and green.
Color blind people have problems distinguishing between certain colors, usually red and green.
Pinhole Glasses
You may have heard about the benefits of pinhole glasses. Do they really work? Could pinhold glasses be useful for you? Here, a review of pinhole glasses, an alternative to prescription eyeglasses.
You may have heard about the benefits of pinhole glasses. Do they really work? Could pinhold glasses be useful for you? Here, a review of pinhole glasses, an alternative to prescription eyeglasses.
Signs of Glaucoma
Learn the signs and symptoms of glaucoma.
Learn the signs and symptoms of glaucoma.
Black Eye Treatment
A black eye is a common result of an injury to the face or head.
A black eye is a common result of an injury to the face or head.
Baby Eye Care
Learn how to keep your baby's eyes clean and healthy.
Learn how to keep your baby's eyes clean and healthy.
Myopia (Nearsightedness)
Myopia simulation.
Myopia simulation.
Diabetic Retinopathy
Diabetic retinopathy is a common complication of diabetes. It may cause poor vision or even blindness.
Diabetic retinopathy is a common complication of diabetes. It may cause poor vision or even blindness.
Reasons for Eye Exam
Learn 4 reasons to schedule an eye exam today.
Learn 4 reasons to schedule an eye exam today.
Pink Eye Symptoms
Learn about the symptoms of pink eye, or conjunctivitis.
Learn about the symptoms of pink eye, or conjunctivitis.
Infant's First Eye Exam
The American Optometric Association (AOA) encourages parents to include a trip to the optometrist in the list of well-baby check-ups. Here is what to expect.
The American Optometric Association (AOA) encourages parents to include a trip to the optometrist in the list of well-baby check-ups. Here is what to expect.
Store Lenses in Water?
Can contacts be stored in plain water?
Can contacts be stored in plain water?
How Long for Contact Lenses?
Can two-week disposable lenses be worn longer than two weeks?
Can two-week disposable lenses be worn longer than two weeks?
Contacts and Allergies
Contact lenses tend to cause problems for people with allergies. Here are five tips to help you get through the season with happy eyes.
Contact lenses tend to cause problems for people with allergies. Here are five tips to help you get through the season with happy eyes.
Eye Allergy Treatment
Learn the top treatments for annoying eye allergies.
Learn the top treatments for annoying eye allergies.
Cost of LASIK
How much does LASIK cost?
How much does LASIK cost?
Teens and Contacts
If you are considering allowing your teenager to wear contacts, here are a few things to think about.
If you are considering allowing your teenager to wear contacts, here are a few things to think about.
Floaters Definition
Learn the definition of floaters.
Learn the definition of floaters.
Protect Eyes from Sun
Harmful ultraviolet (UV) rays can cause sunburn of both the skin and the cornea of the eye, even on an overcast day, according to the American Optometric Association.
Harmful ultraviolet (UV) rays can cause sunburn of both the skin and the cornea of the eye, even on an overcast day, according to the American Optometric Association.
Lasik Side Effects
What side effects can I expect after LASIK?
What side effects can I expect after LASIK?
Lasik
Lasik eye surgery is not for everyone. Find out if you are qualified to be a lasik candidate.
Lasik eye surgery is not for everyone. Find out if you are qualified to be a lasik candidate.
Special Contacts
Decorative contact lenses have become quite popular in recent years, with demand increasing during the Halloween season. Special effect contact lenses are available with or without corrective power, so people who don't usually need contact lenses or glasses may still wear them.
Decorative contact lenses have become quite popular in recent years, with demand increasing during the Halloween season. Special effect contact lenses are available with or without corrective power, so people who don't usually need contact lenses or glasses may still wear them.
Toric Lenses
Toric lenses are lenses are worn to correct astigmatism.
Toric lenses are lenses are worn to correct astigmatism.
Double Vision
Seeing double? The medical term for double vision is diplopia. Double vision occurs if the two eyes are misaligned and are aimed at two different targets.
Seeing double? The medical term for double vision is diplopia. Double vision occurs if the two eyes are misaligned and are aimed at two different targets.
What Is GDx?
The GDx test is useful in the detection and diagnosis of glaucoma.
The GDx test is useful in the detection and diagnosis of glaucoma.
Vision 101
Learn all about your eyes and vision.
Learn all about your eyes and vision.
Optomap Eye Exam
Learn about the dilation-free eye exam, Optomap®.
Learn about the dilation-free eye exam, Optomap®.
Computer Vision Symptoms
If you spend a significant amount of time on a computer each day, it's wise to watch out for these symptoms of computer vision syndrome.
If you spend a significant amount of time on a computer each day, it's wise to watch out for these symptoms of computer vision syndrome.
Astigmatism Tips
Learn a few ways to help minimize unwanted symptoms associated with astigmatism.
Learn a few ways to help minimize unwanted symptoms associated with astigmatism.
Emergency Symptoms
Many eye conditions are minor and temporary. However, these four symptoms require a doctor's immediate attention.
Many eye conditions are minor and temporary. However, these four symptoms require a doctor's immediate attention.
Tints for Sunglasses
Handy tips for picking tints and colors for sunglasses.
Handy tips for picking tints and colors for sunglasses.
Glaucoma Tests
Descriptions of the six tests used to detect the eye disease known as glaucoma.
Descriptions of the six tests used to detect the eye disease known as glaucoma.
Prescriptions Expiration
Why do prescriptions for contact lenses expire?
Why do prescriptions for contact lenses expire?
Disposable Contacts
Disposable contacts are made to be worn for a period of time, then thrown out and replaced with a new pair of lenses. Try colored disposables for fun.
Disposable contacts are made to be worn for a period of time, then thrown out and replaced with a new pair of lenses. Try colored disposables for fun.
Macular Degeneration
Macular degeneration, or age-related macular degeneration, is the leading cause of blindness in older people.
Macular degeneration, or age-related macular degeneration, is the leading cause of blindness in older people.
Reading Glasses
Learn a few tips for buying reading glasses.
Learn a few tips for buying reading glasses.
Things to Tell Your Eye Doctor
Take an active role in your eye care. This list will help you remember things your eye doctor needs to know.
Take an active role in your eye care. This list will help you remember things your eye doctor needs to know.
Strabismus
Strabismus is the term is used to describe eyes that are not straight or properly aligned. It is a deviation of the eyes.
Strabismus is the term is used to describe eyes that are not straight or properly aligned. It is a deviation of the eyes.
Ophthalmic Migraine
Learn the definition of ophthalmic migraine.
Learn the definition of ophthalmic migraine.
Replacing Contact Lens Cases
How often should contact lens storage cases be replaced?
How often should contact lens storage cases be replaced?
Subconjunctival Hemorrhage
A subconjunctival hemorrhage is a broken blood vessel in the eye.
A subconjunctival hemorrhage is a broken blood vessel in the eye.
Kids' Eyeglasses
Does your child need a new pair of eyeglasses? Here are the top six things to look for in kids' eyeglasses.
Does your child need a new pair of eyeglasses? Here are the top six things to look for in kids' eyeglasses.
Vision Insurance Information
Vision insurance can be confusing, but it is to your benefit to understand the differences between medical and vision insurance.
Vision insurance can be confusing, but it is to your benefit to understand the differences between medical and vision insurance.
Blocked Tear Ducts
Blocked tear ducts are common in infants.
Blocked tear ducts are common in infants.
Video Games and Eyestrain
Playing video games for extended amounts of time can lead to eye discomfort, fatigue, blurred vision and headaches.
Playing video games for extended amounts of time can lead to eye discomfort, fatigue, blurred vision and headaches.
Medicare Vision Benefits
Learn about Medicare benefits for vision care.
Learn about Medicare benefits for vision care.
Silicone Hydrogel Lenses
Wearing contact lenses increases the risk of developing dangerous eye infections. Are silicone hydrogel lenses a safer alternative to regular soft contact lenses?
Wearing contact lenses increases the risk of developing dangerous eye infections. Are silicone hydrogel lenses a safer alternative to regular soft contact lenses?
Choroidal Melanoma
Choroidal melanoma is a cancer of the eye that develops in a part of the eye called the choroid. Learn the full definition of choroidal melanoma.
Choroidal melanoma is a cancer of the eye that develops in a part of the eye called the choroid. Learn the full definition of choroidal melanoma.
Diplopia
Diplopia is double vision.
Diplopia is double vision.
Nutrients for Healthy Eyes
Do you know the 6 nutrients to eat for healthy eyes and vision?
Do you know the 6 nutrients to eat for healthy eyes and vision?
Top 7 Risks of Laser Surgery
Refractive surgery often produces great results. However, there are risks involved in any medical procedure. If you are considering undergoing laser vision surgery, it is important to know the possible complications and limitations that may occur.
Refractive surgery often produces great results. However, there are risks involved in any medical procedure. If you are considering undergoing laser vision surgery, it is important to know the possible complications and limitations that may occur.
Before You Have LASIK
Before you schedule LASIK eye surgery, find out what is involved and what could go wrong. LASIK eye surgery is a serious procedure that will affect the rest of your life.
Before you schedule LASIK eye surgery, find out what is involved and what could go wrong. LASIK eye surgery is a serious procedure that will affect the rest of your life.
Could I Have Glaucoma?
Increased eye pressure puts you at risk for developing glaucoma, but does not mean you have the disease.
Increased eye pressure puts you at risk for developing glaucoma, but does not mean you have the disease.
Punctal Occlusion
Punctal occlusion is a technique used frequently for treating dry eye.
Punctal occlusion is a technique used frequently for treating dry eye.
Prescriptive Sunglasses
Learn about prescription sunglasses.
Learn about prescription sunglasses.
Ordering Contacts Online
Remember that contact lenses are medical devices that should be properly fitted and cared for to maintain healthy eyes and vision. Follow the guidelines below when ordering contact lenses online.
Remember that contact lenses are medical devices that should be properly fitted and cared for to maintain healthy eyes and vision. Follow the guidelines below when ordering contact lenses online.
Blocked Tear Duct
Newborn babies sometimes have blocked tear ducts.
Newborn babies sometimes have blocked tear ducts.
Cataract
Cataract simulation.
Cataract simulation.
Iris
The iris is the colored part of the eye.
The iris is the colored part of the eye.
Glaucoma Facts Quiz
glaucoma quiz: Test your knowledge of glaucoma.
glaucoma quiz: Test your knowledge of glaucoma.
Asthenopia
Asthenopia is a collection of symptoms that causes eye fatigue or tiredness.
Asthenopia is a collection of symptoms that causes eye fatigue or tiredness.
Eye Allergy
Eye allergies can produce many annoying symptoms, including itchy, red eyes.
Eye allergies can produce many annoying symptoms, including itchy, red eyes.
Sports Injuries
Sports and recreational activities cause more than 40,000 eye injuries each year, most of which could be prevented.
Sports and recreational activities cause more than 40,000 eye injuries each year, most of which could be prevented.
Diet and Eye Disease
Studies show links between good nutrition and eye health.
Studies show links between good nutrition and eye health.
Sunglass Shopping
Learn all about what to look for when shopping for sunglasses.
Learn all about what to look for when shopping for sunglasses.
Latisse
Many people are asking their eye doctors for Latisse, an FDA approved drug to increase the quality and quantity of eyelashes.
Many people are asking their eye doctors for Latisse, an FDA approved drug to increase the quality and quantity of eyelashes.
Computers and Vision
I work at a computer every day. Can computers harm vision?
I work at a computer every day. Can computers harm vision?
Myopia Control
Myopia control is the term given to different methods that try to influence vision and brain development, or alter the growth of the eye itself to retain clear eyesight.
Myopia control is the term given to different methods that try to influence vision and brain development, or alter the growth of the eye itself to retain clear eyesight.
Retinitis Pigmentosa
Retinitis pigmentosa simulation.
Retinitis pigmentosa simulation.