Frequently Asked Questions

How does KidsVisionCheck work?

KidsVisionCheck detects the light from the camera flash as it is reflected from the back of the eye. This is the “red eye” sometimes seen in photographs. The quality of the reflection is determined by how the light passes through the eye. If the reflection is abnormal, it means that something is interfering with the path of the light.

What can KidsVisionCheck detect?

Anything that interferes with light traveling through the eye can cause an abnormal reflection that may be detected by KidsVisionCheck. The most common problems are glasses problems, like nearsightedness (myopia), farsightedness (hyperopia), and astigmatism. KidsVisionCheck can also tell if the eyes are not lined up properly, like cross eyes or wall eyes (strabismus). It is important to detect these problems early. If they are not detected and treated, they can lead to loss of vision because of amblyopia.

What is Amblyopia?

Amblyopia is loss of vision that is caused by common childhood vision problems that are untreated. The ability to see clearly is not fully developed at birth. The pathways between the eyes and the brain must mature. For them to mature, the eyes must send a clear picture to the brain, so that the brain can learn to detect and interpret it.

Eyes that are out of focus from refractive errors like nearsightedness, farsightedness and astigmatism can’t send clear pictures to the brain. Therefore, the brain never learns to detect clear vision. This is one cause of amblyopia. 

Eyes that are poorly aligned such as with crossed eyes, send two totally different pictures to the brain. To deal with this, the brain can ignore one of those pictures. The brain then never learns to process images from that eye. This is another cause of amblyopia.

If something prevents well focused light from reaching the back of the eye like a cloudy lens (cataract) or cloudy cornea (leukoma) or others, the brain never learns to process images from that eye. That is another cause of amblyopia. KidsVisionCheck can detect all of these causes of amblyopia.

What are some common things that alter the path of light through the eye?

Lens problems – the lens sits behind the iris, or colored part of the eye. If the lens is off center or improperly shaped it can’t focus a clear image to the back of the eye. When the back of the eye does not get a clear image, vision fails to develop normally. This is another cause of amblyopia.

Ectopic lenses are off center so that light goes through the edge of the lens rather than the center.

Anterior or Posterior Lenticonus – the front of the lens is shaped more like an ice cream cone than the smooth round surface of a ball.

Spherophakia – when the lens is too round causing light to be focused improperly. It is often associated with glaucoma, or high eye pressure that can lead to permanent blindness

Refractive errors (glasses problems) – refractive errors interfere with the proper focus of light on the back of the eye. This can lead to amblyopia. These problems can usually be treated with glasses

Nearsightedness (Myopia). Eyes with myopia can see well up close but see poorly in the distance.

Farsightedness (Hyperopia). Eyes with hyperopia have difficulty seeing things up close.

Astigmatism. Eyes with astigmatism cannot see well up close or at a distance. It occurs when the front surface of the eye is curved in two different directions, more like the side of a football, than the side of a baseball where the curves are the same in all directions.

What are common things that block light being reflected from the back of the eye?

Eales’s disease – Eales disease is one of several conditions that involve inflammation of parts of the inside of the eye. When there is inflammation, the clear fluids of the eye become cloudy, preventing normal passage of light and interfering with vision.

Toxocara canis Toxocara cati – This is a disease caused by a worm normally found in cats and dogs. When it infects people, it can travel to several places in the body including the eye, where it can cause inflammation and great damage to the retina

Toxoplasmosis – This is a parasite from cats. Like Toxocara canis and Toxocara cati, the parasite can travel to the retina and cause inflammation and damage.

Retinoblastoma – This is the most common eye cancer in children. It occurs in the back of the eye

Melanoma – This is a tumor in the eye. It is uncommon in children.

Osteoma – In some cases, a portion of the tissues in the back of the eye can be replace by bone.

Medulloepithelioma – Medulloepitheliomas are extremely dangerous, highly malignant cancers that can occur in the eyes of children. Fortunately, they are rare.

PHPV – PHPV (Persistand Hyperplastic Primary Vitreous) is an abnormal development of the clear gel that fills the back of the eye.

Retinopathy of prematurity – This is an abnormal development of the blood vessels in the eye that occurs in children who were born prematurely and who required oxygen treatment.

Coat’s disease – This is an abnormal development of blood vessels in the eye. These blood vessels leak fluid and blood into the eye interfering with vision and causing inflammation.

Von Hippel Landau – This is a disease that runs in families. People with Von Hippel Landau grow tumors in many organs in the body including the eyes. While the tumors are usually benign, they can interfere with vision by damaging the retina or interfering with the normal passage of light.

Norrie Disease – This is an abnormal development and degeneration of the retina most often seen in males, present at birth or an early age.

Best Disease – Best disease runs in families. People with Best disease develop a yellow “egg yolk” appearance in the back of the eye, often at an early age.

Coloboma – This is a failure of normal development of the eye so that the retina does not go completely around the inside of the eye leaving a gap.

Retinal detachment – When a retinal detachment occurs the retina, which is normally attached to the inside surface of the eye, is pulled from its normal position in towards the center of the eye. If it is not repaired promptly the retinal tissue will die from lack of nourishment.

Retinal dysplasia – This is an abnormal development of the retina.

What are common things that prevent light from going straight into the eye?

Strabismus – a misalignment of the eyes so that the eyes get two different pictures. When this happens, the brain can’t put the two images together. The brain then chooses to use the image from one eye and allow the vision in the other eye fail to develop. This is another cause of “Amblyopia.”

Crossed eyes (Esotropia) – a condition where one or both eyes turn in toward the nose. It can be constant or intermittent. If untreated it will likely result in poor vision development called “Amblyopia.”

Wall eyes (Hypertropia) – a condition where one or both eyes turn out away from the nose. If untreated it will likely result in poor vision development called “Amblyopia.”

Brown’s syndrome – a condition where one of the muscles that moves the eye is stuck so that the eye cannot look up when it is turned toward the nose.

Duane’s syndrome – An eye muscle issue that can make it impossible to move the eye toward the nose, away from the nose, or both. It is due to the nerves should go to the eye muscles going to the wrong muscle.

Third nerve palsy – The third cranial nerves control four of the six muscles that move the eyes. If it can’t send proper signals, the eyes cannot move properly.

Fourth nerve palsy – The fourth cranial nerves control muscles that move the up and in toward the nose. If they aren’t working properly the eyes cannot move properly.

Sixth nerve palsy – The sixth cranial nerves control the muscles that move the eyes out, away from the nose. If one or both sixth cranial nerves are not working properly the eyes will be cross eyed and unable to move to the side.

Hypertropia – Hypertropia means that one of eyes is looking up, higher than the other. When this happens, the eyes get two different pictures, and the brain can’t put them together.

What are common things that block light from getting into the eye properly?

When light can’t get into the eye properly, the visual system doesn’t develop properly. If these problems are not corrected at an early age, it may never be possible to develop normal vision. This poor vision development is a type of “Amblyopia.’

Corneal Dermoid – Corneal dermoids are benign congenital tumors that can interfere with vision.

Cataract – Cataracts are cloudiness or opacity of the lens inside the eye that prevent the eye from forming a clear image.

Corneal scars (Leukoma) – These scars can be due to trauma or infection. They can prevent good vision if not treated.

Congenital Glaucoma – When children are born with glaucoma the cornea swells with too much fluid causing a cloudiness that prevents good vision. Ultimately, if not treated, it causes the eye to go permanently blind.

Ptosis – This is a droopiness of the eyelid due to poor muscle development. The eyelid can droop enough to prevent good vision.

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