eye disorder

8/9/2019 Eye Disorder

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Ma.Carmela Ayala

Definitions: Strabismus is a term for misaligned eyes. More than a dozen types of rossing

misalignment are called Esotropia. Out-drifting is called exotropia and updrifting is called

hypertropia.Detection: Parents and pediatricians often are first to notice crossing in a new-born or infant. The

eyes may stay crossed, they may occasionally cross or the child may look with one eye while

always crossing the other. When an eye turns in, it may look out poorly and it may show minimalwhite on the inside toward the nose. False crossed appearance (Pseudostrabismus) can occur

when an infant's nasal skin fold covers the inside white of an otherwise straight eye. When a

straight eye looks at a light, a reflection centers in the pupil and a dark red reflex is present ascan been seen in some flash photographs. True crossing can be detected by abnormal light

reflections and abnormal red reflexes (Bruckner's Reflex).

Sequelae: Under normal conditions, we have very poor vision at birth (20/2000) in each eye and

gradually develop good vision in each eye which remains permanent after age ten years. Depthperception from binocular vision is first measured by age 4 months and improves up to age ten

years. If an eye has vision blocked (i.e. from juvenile cataract), or if the eye is poorly focused

(i.e. from too much astigmatism or unequal farsightedness) or if the eyes remain misaligned

(strabismus), then the brain will fail to learn good vision and wil have absent or subnormal depthperception (Amblyopia). Pediatric ophthalmologists strive to prevent all forms of amblyopia but

cannot do so without much help from parents.Accommodative Convergence The brain normally controls three eye functions at once; close

focus (accomodation), turning each eye in to align on a near object (convergence) and pupil

constriction. It is impossible to separate these normal brain functions. When we focus close, our

eye should turn in. As a result of normal alignment of each eye, images are correctly projected tothe brain resulting in normal visual development of each eye and the development of binocular

vision and depth perception over the first ten years of life. Improper alignment of the eyes

(strabismus) can result in poor development of the vision in the less preferred eye (amblyopia)and absent depth perception.

Near sighted people can easily focus on close objects but require glasses to see distance. Whennear sighted people use the focus muscles in their eyes, they focus even closer-up to the tip of thenose! Far sighted people are un-focused at distance and more so at near when they do not use the

focus muscles in their eyes. In order to focus on a distant object they must use some eye focus

power (accommodation). Far sighted people must use lots of focus muscle power to see nearobjects.

It is common for far-sighted children between the age of 18 months and 3 years to start crossing

their eyes especially for near objects and when tired. This is because children start wanting to

focus on details after age one, and the extra focus power required by the far-sighted child isconnected in their normal brains with turning the eyes in. Usually, prescription of the correct far-

sighted glasses (after dilated exam) will result in straight eyes for these children.

Accomodative with increased AC/A: While it is normal for our eyes to turn in a certain amountfor a given amount of close focusing, some children demonstrate an exaggerated amount of

crossing for a given amount of close focusing. This tendency resides in their brain. Bifocal

glasses and an eye drop called phospholine iodide (PI) can help such patients. The PI drops andthe bifocals make close focusing easier and therefore reduces the crossing tendency which is

controled by that child's brain. PI can cause little bumps in the pupil but the main complication

of PI drops is the potential to prolong muscle relaxants during general anesthesia since the drop

gets gradually absorbed into the body as well as the eyes. If your child is on PI drops, remember
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to notify your anesthesiologist in the event of surgery.

Vergence amplitudes (Jumping over a stick- analogy) Although most people appear to have

straight eyes, most actually are compensating for small amounts of mis-alignment (phorias). Theability to make adjustments of phorias is called a vergence amplitude. A vergence amplitude

might be likened to being able to jump over a stick. Most of us can jump over a stick 10 inches

off the ground or perhaps 15 inches but rarely can we jump 25 inches. The same for a personsability to make adjustments for amounts of misalignment of the eyes measured in prism diopters.

Two prism diopters is about the same as one degree. Most people can only adjust for 15 or less

prism diopters of crossing and the more adjustment requires more effort. Some older people areplagued by doublevision because they lose their vergence amplitudes.

Tendency to stay straight (analogous to marriage for Billy Graham's wife Ruth and Elizabeth

Taylor) We are born with tendencies to keep our eyes aligned. Some of us are born with very

poor abilities to keep our eyes aligned (drift-tendency) which often results in early crossing ofthe eyes (essential infantile esotropia). Others may have had a mechanical reason for early

crossing greater than their ability to compensate for it. Crossed eyes can almost always be

straightened by glasses or surgery. Over time, some straightened eyes stay straight while others

drift away from straight. Eye doctors are unable to know whether a cross-eyed child is a drifteror one who will stay straight until attempts have been made for the first few years to help the eye

be straight. For those with a drifting tendency, good vision can usually be attained in each eyebut even as an adult the eyes may continue to drift out, in or vertically. The tendency to keep our

eyes straight might be likened to the future tendency of a maiden to stay married for life. The

future Ruth Graham had a strong tendency to stay married while the future Elizabeth Taylor did

not. We often don't know a given child's tendency to stay straight for several year, or in the caseof Elizabeth Taylor, several attempts at marriage. Some children require several surgical

procedures to keep their eyes reasonably straight.

Essential Infantile Esotropia (EIE): This is a common form of crossing which is also known ascongenital esotropia. Not every child with this condition is born crossed, however. Most patients

with EIE cross before age 6-12 months and do not have very much far-sightedness. Vertical

misalignment can accompany EIE. In addition to crossing, An EIE patient may demonstratemore crossing up (A-pattern), more crossing down (V-pattern), overaction of the oblique muscles

or up-drift tendency of each eye (DVD).Surgery is almost alway required to allow straight eyes

and prevention of amblyopia in an EIE patient.Mixed Mechanism: Several children are eventually found to have crossing partly treatable by

glasses and partly requiring surgical treatment resembly EIE.

Duane's Syndrome/ 6th Nerve Palsy: The sixth nerve from the brain stem controls the muscle

which pulls our eyes out. A weak sixth nerve can be a cause of an in-turning eye. If the sixthnerve weakness occurs before birth, that eye may not turn completly out. During development,

some of the nerve from the in-turning muscle may attach to the out-turning muscle. In this

condition (Duane's Syndrome) the eye doesn't turn completely out and the eye lids narrow whenthe eye turns in. Surgery is occasionally required to help the child look straight ahead.

Sensory strabismus: We keep our eyes straight by superimposing the images from each eye to

avoid double vision. If one of our eyes sees very poorly, then that eye may drift out of alignment.Poor vision in a child's eye can be caused by poor development of the optic nerve or retina,

potentially fatal retinal tumors, cataracts or infections. It is critical to fully examine any child

whose eyes are not aligned.

Esophoria/ Intermittent Esotropia: Occasionally, some children have eyes that gradually drift in
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when the child is tired or day-dreaming. This may start at any age. Such crossing is compensated

well when the child is alert enough to exert the muscle energy to pull the eyes back straight.

Surgery or glasses are required only when the child has enough difficulty compensating for thedrift.

Prevalence: Esotropia is the most common form of strabismus constituting 1/2 to 2/3 of all

misaligned eyes. About 5% of people have strabismus. The more common types have bolderboxes in the figure below.

Accommodative Esotropia can often be treated wi th hyperopic spectacles, bifocals and possibly Fresnel Prisms. Some patientsstill need strabismus surgery in addition to attain binocular alignment.Essential Infantile ("Congenital") Esotropia:

:After Bilateralmedial Rectus Recession Surgery

Definition of Amblyopia: potentially permanent deficiency of brain vision learning.

Treatment of Amblyopia: Refractive Correction, Patching and PenalizationShield Occluderfor non-compliant patch patients

The purpose ofVision Screening is detection of conditions that lead to amblyopia early enough

that treatment will be effective.
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Ma.Carmela Ayala

Amblyopia, also known as "lazy eye," occurs in 2% to 3% of babies and, in the US, in 75,000 3-year-olds per year. In this condition, poor vision in one or both eyes may result in the eyes not pointing inthe same direction (misalignment) or in the eyes becoming crossed (strabismus). Amblyopia may beinherited or caused by uncorrected Refractive error(nearsightedness, farsightedness, or astigmatism;see Refractive Errors, below). Amblyopia results when there is a difference in the quality of the imagesrecorded by each eye and sent to the brain. The brain picks the better of the two images sent to it anddisregards the blurry or cloudy image. When the brain disregards this image, the visual system

develops more slowly for the eye that sent the discarded image than for the eye that sent the goodimage.

Parents usually cannot recognize a lazy eye merely by looking at it, because the problem is in thebrain as well as the eye. The brain blocks vision from the lazy eye because the brain is unable to useboth eyes together. An infant with normal vision learns to use both eyes together (binocular vision),and the pictures from the left and right eye are then combined (fused) into one picture by the brain.Because binocular vision permits us to tell how far away an object is in relation to other objects(depth perception), children with amblyopia have poor depth perception.

Signs of Amblyopia

Most babies with amblyopia show no obvious signs of the condition, which must be diagnosed by an

eye doctor. In some infants, however:

The weak eye turns (see the diagrams under "Strabismus").

The weak eye tends to close.

The child squints.

The child constantly rubs one eye.

If you notice any of these signs in your child, let your eye doctor know right away.

Treatments for Amblyopia

Patch therapy: A patch is worn over the good eye so the weak eye will be used and willdevelop. In this situation, the BabyEyesT DVD can help to stimulate and strengthen vision in

the weak eye.

Glasses, which help correct poor vision in one or both eyes.

Eye surgery may be required in rare cases in which the child is born with a clouded crystalline

lens (a congenital cataract), or if amblyopia is combined with strabismus.

If amblyopia is not treated before 4 years of age, it can become permanent and untreatable.

This is one reason why a visit to the eye doctor before 14 months of age is so important!

Strabismus

Strabismus is the medical term for "crossed" or "turned" eye. This condition occurs in 2% to 4% ofchildren. There are three common types of strabismus, as illustrated in the diagrams below:
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Crossed eye (esotropia)

Wall eye (exotropia)

One eye pointing upward or downward (vertical deviation)

Signs of Strabismus

Strabismus can be indicated by all of the signs of amblyopia plus a constant or occasional turning of

the eyes or tilting of the head.

Treatments for Strabismus

When vision is normal, the images sent by each eye to the brain are fused together so the brainreceives one combined image. Strabismus is treated by training both eyes to work together to sendone fused image to the brain for interpretation. Treatments include:

Patching

Glasses

Surgery to correct weakness or imbalance in the eye muscles.

Pseudostrabismus

At birth, the upper part of the nose (the Bridge, the space between the eyes) is flat. Some babieshave prominent folds of skin between the bridge of the nose and the inner corners of the eyes. Theseskin folds (epicanthal folds) may make the baby seem cross-eyed, when actually the baby's eyes arenormal. This "false" cross-eyed appearance (pseudostrabismus) gradually vanishes as the baby's nosebridge grows out and separates the eyes. There is no need to worry about this condition, as it is notreally an eye disorder at all but only seems like one. Of course, whenever you become concernedabout your baby's vision for any reason, you should contact an eye doctor (see "Warning Signs at AnyAge," below)

Blocked tear duct

Babies often develop a blocked tear duct (nasolacrimal duct obstruction). In this condition, thedelicate drainage tube that leads from the eye to the nose is clogged, or the membrane that coversthis tube's entryway does not open (as it normally would after birth).

Signs of blocked tear duct
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Too much tearing (tears may even run down the cheeks).

Watery or cloudy liquid draining from the eyes.

Crusty eyelashes upon awakening.

Constant rubbing of the eyes.

Treatments for blocked tear duct

Mild pressure is applied to the area between the eye and the nose and this area is gently

massaged.

Antibiotic drops or ointments are applied.

Corrective surgery is done if the above options do not work over time.

Refractive errors

Refractive errors are problems in the way the crystalline lens and the cornea focus light on the retina.In order for the eye to send a clear, sharp image to the brain, light rays need to be brought to a point(focused) directly on the retina, and particularly on the center of the retina (the fovea centralis; seethe diagram above under "How Do We See?"). In some common disorders, glasses or contact lenses

are needed to focus the light.

Near-sightedness (Myopia) occurs in 4% of babies. A person is near-sighted when lightrays are focused in front of the retina, rather than on the retina (specifically, light focusestoward the center of the eye rather than on the back of the eye). This can occur when the eyeis too deep or the cornea or is too curved.

Far-sightedness (Hyperopia) occurs in 20% of babies. A person is far-sighted when the

light rays are focused behind the retina, rather than on the retina (specifically, light focusesbehind the back of the eye rather than on it). This can happen when the eye is too shallow orthe cornea is not curved enough. Most children can correct for far-sightedness by flexingmuscles inside their eyes. This constant flexing can cause headaches, eyestrain, and turning ofthe eye (strabismus).
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Astigmatism (distortion) occurs in 10% of babies. In this condition, the cornea is football-shaped rather than spherical, and so reflects light in a distorted way. Two perpendicular setsof light rays focus at different points on or near the retina, so the image perceived by thebrain is warped. Astigmatism can occur by itself or together with other refractive errors.

Less common eye diseases in children

While the above eye disorders are common and easy to correct if detected and treated early, eyediseases can be much more serious. Some of them can be treated and cured; others are incurable.Fortunately, these diseases are rare. Examples of eye diseases are:

Retinopathy of prematurity (ROP): Babies born with a very low birth weight have an increased riskof developing abnormal peripheral retinal blood vessels that can cause the retina to come loose(detached retina), which can lead to blindness. Those babies who do not develop this problem inchildhood still have an increased risk of retinal detachment later in life, and should be seen regularlyby an eye doctor to check for retinal detachments.

Familial (congenital) blindness: If there is a history of blindness in the family of either the fatheror mother, parents may want to seek genetic counseling to help determine the risk of blindness intheir children.

Retinitis pigmentosa: In this inherited disease, the retina in both eyes degenerates more and more

over time (progressively). Children become unable to see at night (develop night blindness) and thenlose their side (peripheral) vision. Tunnel vision (no side vision at all, as if in a tunnel) develops,followed by complete blindness.

Leber's congenital amaurosis: Blindness or near-blindness occurs in children with this diseasebecause they lose nerve function in the retina of both eyes. A jerky movement of the eyes(nystagmus) may occur, as well as hypersensitivity to light and sunken eyes.


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Congenital Glaucoma: In this disease, high pressure of the fluid within the eye, together with anenlarged cornea, can cause nerve damage in newborns and infants. A common cause is malformationof some parts of the eye. Too much tearing (excessive watering) can be a warning sign of congenitalglaucoma, but may also indicate less serious conditions, such as a blocked tear duct.

Congenital cataract: The crystalline lens, usually crystal clear at birth, is cloudy (opaque), so notenough light from the outside object reaches the retina. Vision is unclear or blocked. This disease can

be cured by eye surgery, which is often necessary. Cataracts are also common in the elderly, in whomthey also can be cured by surgery.Dermoid cysts: These are bumps usually found on the side of the head near the eyebrow. They arenot cancer, but are actually capsules containing skin tissue, hair, fat, or other body tissue. Dermoidcysts should be removed before the child begins to walk, because they can break open during a falland cause painful inflammation.

Warning signs

Make an appointment with an eye doctor-either anOptometrist or an Ophthalmologist - if you seeany of the following signs in your child:

Eyes flutter quickly from side to side (nystagmus).

Eyes are watery all the time.

Eyes are always sensitive to light.

Eyes change in any way from their usual appearance.

White or yellow material appears in the pupil-the dark circle at the center of iris (the colored

area of the eye).

Redness in either eye persists for several days.

Puss or crust appears in either eye.

Eyes looked crossed or "wall-eyed."

The child constantly rubs his or her eyes.

The child often squints.

The child's head is always tilted.

Eyelids tend to droop.

One or both eyes seem to bulge.

One pupil is larger or smaller than the other (asymmetric pupil size).

Baby does not make eye contact by 3 months of age.

Baby does not focus on and follow objects by 3 months of age.

Baby does not reach for objects by 6 months of age.

Baby covers or closes one eye.

One eye constantly or sometimes (intermittently) turns in, out, up, or down.
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