Index
It is a term used to describe several specific ophthalmic entities.
Amblyopia
Amblyopia, also called lazy eye, is a vision disorder because the eye and the brain do not work well together. It decreases vision in one eye that otherwise appears typically normal.
It is the most common cause of decreased vision in one eye among children and younger adults. The cause of amblyopia can be any condition that interferes with focus during early childhood.
This can occur from misalignment of the eyes, an irregularly shaped eye such that focusing is difficult.
Vision is not immediately restored once the underlying cause has been fixed, as the mechanism also involves the brain. Amblyopia can be difficult to detect, so vision testing is recommended for children between four and five.
Early detection improves the success of treatment. Glasses may be all the necessary treatment for some children. If this is not enough, medicines have been used that force the child to use the weaker eye.
This is done by wearing a patch or placing atropine in the stronger eye. Without treatment, amblyopia usually persists into adulthood. The evidence regarding treatments for adults is poor.
Amblyopia begins at the age of five. The disorder is estimated to affect 1-5% of the population in adults. Although treatment improves vision, it usually does not restore it to normal in the affected eye.
Amblyopia was first described in the 17th century. The condition can make people ineligible to be pilots or police officers.
Signs and symptoms
Many people with amblyopia, especially those with only a mild form, are unaware that they have the condition until they are tested at an older age, as a vision in their stronger eye is normal.
However, people often have poor stereo vision, as it requires both eyes. People with amblyopia may have poor pattern recognition, poor visual acuity, and low sensitivity to contrast and movement in the affected eye.
Amblyopia is characterized by several functional abnormalities in spatial vision, including reductions in visual acuity, contrast sensitivity function, vernier acuity, spatial distortion, abnormal spatial interactions, and altered contour detection.
In addition, people with amblyopia suffer from binocular abnormalities such as impaired stereo acuity (stereoscopic acuity) and abnormal binocular summation.
In addition, there is a phenomenon of overcrowding. These deficits are generally specific to the amblyopic eye. However, subclinical deficiencies of the “better” look have also been demonstrated.
People with amblyopia also have binocular vision problems, such as limited stereoscopic depth perception, and generally have difficulty viewing 3-D images on hidden stereoscopic displays, such as autostereograms.
However, the depth perception of monocular signals, such as size, perspective, and parallax of motion, remains normal.
Pathophysiology
Amblyopia is a developmental problem in the brain, not an inherent organic neurological problem in the eyeball (although organic problems can lead to amblyopia which may continue to exist after the organic issue has been resolved by medical intervention).
The part of the brain that receives images from the affected eye is not adequately stimulated and does not develop its full visual potential. A direct brain examination has confirmed this.
David H. Hubel and Torsten Wiesel won the Nobel Prize in Physiology or Medicine in 1981 for their work in showing the magnitude of damage to the ocular dominance columns produced in kittens by sufficient visual deprivation during the so-called “critical period.”
Humans’ maximum “critical period” is from birth to two years.
Diagnosis
Amblyopia is diagnosed by identifying low visual acuity in one or both eyes, out of proportion to the structural abnormality of the eye, and excluding other visual disturbances as causes of decreased visual acuity.
When the eye’s optics are fully corrected, it can be defined as an interocular difference of two lines or more in understanding (for example, in the Snellen table).
In young children, visual acuity is difficult to measure. It can be estimated by observing the patient’s reactions when one eye is covered, including keeping the patient’s ability to follow objects with one eye.
Stereotypes such as the Lang stereotype are not reliable exclusion tests for amblyopia. A person who passes the stereotypic Lang test is unlikely to have strabismic amblyopia but could have refractive or deprivation amblyopia.
It has been suggested that binocular retinal birefringence scanning can identify, even in very young children, amblyopia that is associated with strabismus, microstrabismus, or reduced fixation accuracy.
Diagnosis and treatment of amblyopia as soon as possible are necessary to keep vision loss to a minimum. Screening for amblyopia is recommended for everyone between three and five.
Treatment
The treatment of strabismic or anisometropic amblyopia consists of correcting the visual deficit (using the necessary prescription for glasses) and, often, forcing the amblyopic eye, patching the good eye, instilling topical atropine in the healthy eye, or both.
About repair against atropine, a drawback is observed in the use of atropine; the drops can have a side effect of creating nodules in the eye that a corrective ointment can counteract.
When treating amblyopia, care should also be taken of overarching or over-criminalizing the good eye, as this can create so-called “reverse amblyopia.”
The eye patch is usually done on a part-time schedule of about 4-6 hours per day.
Treatment continues as long as vision improves. If it does not improve, it is not worth continuing to patch for more than six months if it does not improve. Treatment of 9-year-olds through adulthood is possible through applied perceptual learning.
Deprivation amblyopia is treated by removing the clouding as soon as possible, then patching or penalizing the good eye to encourage the use of the amblyopic eye.
The earlier treatment is started, the easier and faster the treatment will be and the less psychologically damaging. Also, achieving 20/20 vision is higher if treatment is started early.
One of the German public health insurance providers, Barmer, changed its policy to cover, as of April 1, 2014, the costs of an app for amblyopic children whose condition has so far not improved through patches.
The app offers specific eye exercises that the patient performs while wearing an eye patch.
Squint
Strabismus, also known as crossed eyes, is a condition in which the eyes do not line up correctly when looking at an object.
The eye that focuses on an object can alternate. The condition can be present occasionally or constantly.
If present for much of childhood, it can lead to amblyopia or loss of depth perception. If the onset is during adulthood, it is more likely to result in double vision.
Strabismus can occur due to muscle dysfunction, farsightedness, brain problems, trauma, or infections. Risk factors include premature birth, cerebral palsy, and a family history of the condition.
Types include:
- Esotropia, where the eyes meet.
- Exotropia is where the eyes diverge.
- Hypertropia where vertically misaligned.
They can also be classified according to whether the problem is present in all directions a person looks (comitant) or varies by demand (incomitant).
The diagnosis can be made by observing the light reflected in the person’s eyes and finding that it is not centered in the pupil. Another condition that produces similar symptoms is a disease of the cranial nerve.
Treatment depends on the type of strabismus and the underlying cause. This can include wearing glasses and possibly surgery. Some types benefit from early surgery. Strabismus occurs in about 2% of children.
The term is from the Greek strabismós, which means “strabismus.” Other words for the condition include “strabismus” and “eye shoot.” “Wall-eye” has been used when the eyes move away.
Signs and symptoms
The arrow / dotted line indicates the fixing distance. When observing a person with strabismus, the misalignment of the eyes can be pretty evident. A patient with a constant eye roll of significant magnitude is quickly noticed.
However, casual observation can easily miss a small magnitude or intermittent strabismus. In either case, a visual health professional can perform various tests, such as the coverage test, to determine the extent of the strabismus.
Symptoms of strabismus include double vision and eye strain. To avoid double vision, the brain can adapt by ignoring one eye.
There are often no noticeable symptoms other than a minor loss of depth perception in this case.
This deficit may not be noticeable in someone who has had a squint from birth or early childhood, as they have likely learned to judge depth and distance using monocular cues.
However, constant unilateral strabismus causing continuous suppression risks amblyopia in children.
Intermittent, small-angle strabismus is more likely to cause disruptive visual symptoms. In addition to headaches and eye strain, symptoms can include an inability to read comfortably, reading fatigue, and unstable or “jittery” vision.
Diagnosis
During an eye exam, a test such as the coverage test or the Hirschberg test is used to diagnose and measure strabismus and its impact on vision.
Retinal birefringence scanning can screen young children for the misalignment of the eyes. Several classifications are made when diagnosing strabismus.
Latency
Strabismus can be overt or latent. A manifest deviation, or heterotrophy (which can be that Exo, hyper, hypocyropia, cyclotropia, or a combination of these), is present while the patient is viewing a binocular target without occlusion of either eye.
The patient cannot align the gaze of each eye to achieve fusion. A latent deviation, or heterophoria, is only present after the disrupted binocular vision, usually covering one eye.
This patient can usually maintain fusion despite the misalignment when the positioning system relaxes.
Intermittent strabismus is a combination of these two types, where the patient can achieve fusion but occasionally or frequently hesitates to the point of overt deviation.
Start
Strabismus can also be classified according to the time of onset, whether it is congenital, acquired, or secondary to another pathological process. Many babies are born with slightly misaligned eyes, usually overcome between six and 12 months.
Acquired and secondary strabismus develop later. The onset of accommodative esotropia, an overconvergence of the eyes due to accommodation effort, is mainly in early childhood.
Acquired non-accommodative strabismus and secondary strabismus develop after normal binocular vision develops. In adults with a previously normal alignment, the onset of strabismus often results in double vision.
Any disease that causes vision loss can also cause strabismus, resulting from a severe and traumatic injury to the affected eye.
Sensory strabismus is due to vision loss or impairment, leading to horizontal, vertical, or torsional misalignment, and the eye with poorer vision shifts slightly over time. Very often, the result is horizontal misalignment.
Its direction depends on the patient’s age. The damage occurs: patients whose vision is lost or impaired at birth are more likely to develop esotropia, while patients with loss or impairment of acquired image mainly develop exotropia.
In the extreme, complete blindness in one eye usually leads the blind eye to return to an anatomical position of rest.
Although many possible causes of strabismus are known, including severe and traumatic injuries to the affected eye, no specific cause can be identified in many cases. The latter is usually the case when strabismus is present from early childhood.
Results from a US cohort study indicate that the incidence of adult-onset strabismus increases with age, especially after the sixth decade of life, peaks in the eighth decade of life, and the risk of the life of being diagnosed with adult strabismus is approximately 4%.
Laterality
Strabismus can be classified as unilateral if the single eye is consistently deviating or alternate if either eye can be seen to vary.
Strabismus alternation can occur spontaneously, with or without subjective awareness of the alternation.
Various tests can also trigger the alternation during an eye exam. Unilateral strabismus results from a severe or traumatic injury to the affected eye.
Address
Horizontal deviations are classified into two varieties. That describes inward or convergent variations toward the midline. Exo describes external or divergent misalignment. Vertical deviations are also classified into two types.
Hyper is the term for an eye whose gaze is directed higher than the other eye, while hiccup refers to an eye whose gaze is directed downward.
Cycle refers to torsional strabismus, which occurs when the eyes rotate around the anteroposterior axis to become misaligned and is quite rare.
Naming
Directional prefixes are combined with -tropia and -Poria to describe various types of strabismus. For example, there is constant left hypertropia when a patient’s left eye points higher than the right.
A patient with intermittent right esotropia has a right eye that occasionally drifts toward the patient’s nose but can align with the gaze of the left eye at other times.
A patient with a mild exophoria can maintain fusion under normal circumstances, but when the system is disturbed, the relaxed posture of the eyes is slightly divergent.
Other considerations
Strabismus can be classified as follows:
- Paretic strabismus is due to paralysis of one or more extraocular muscles.
- The non-apparent strabismus is not due to paralysis of the extraocular muscles.
- Comment (or concomitant) strabismus is a deviation with the same magnitude regardless of gaze position.
Concomitant (or incomitant) strabismus has a magnitude that varies as the patient shifts his gaze up, down, or sideways.
Non-apparent strabismus is generally concomitant. Most types of infantile and infantile strabismus are comitant.
Paretic strabismus may or may not be comitant. Limited eye rotations cause incoherent strabismus due to extraocular eye movement (ocular regulation) restriction or extraocular muscle paresis.
Incoherent strabismus cannot be completely corrected with prism glasses, as the eyes would require different degrees of prismatic correction depending on the direction of gaze.
Types of strabismus include Duane syndrome, horizontal gaze palsy, and congenital fibrosis of the extraocular muscles.
When the misalignment of the eyes is significant and noticeable, the strabismus is called the wide-angle, referring to the angle of deviation between the sightlines of the eyes.
Less severe twists of the eye are called small-angle strabismus. The degree of strabismus can vary depending on whether the patient is looking at a distant or near target.
Ptosis
When you look in the mirror, do you see sleepy eyes? Maybe your upper eyelids sag a little or cover your pupil. It could be ptosis, a fancy way of saying “fall.”
What are the symptoms?
The main sign is that one or both eyelids droop. It is not painful, but it can block your view.
You may need to tilt your head back and lift your chin to see better. Or you may have to raise your eyebrows to lift your eyelids. Over time, these movements can affect your head and neck.
If your child has it, he could also develop amblyopia or “lazy eye.” It is a poor sight in one eye that did not develop normally during childhood.
This could happen if the cap falls off so much that it blocks your vision or makes things blurry. Treat it early in infancy so it doesn’t cause long-term vision loss.
What causes it?
You can get it in various ways. Sometimes babies are born with it. You may have ptosis as an adult when the nerves that control the muscles in your eyelid are damaged. An injury or illness may follow that weakens the muscles and ligaments that lift the eyelids.
Sometimes it comes with age. The skin and muscles around the eyes become weaker. Surgery, such as LASIK (Laser-assisted in Situ Keratomileusis) or cataract surgery, can tighten the eyelid. An eye tumor can also cause ptosis.
How is it treated?
If it doesn’t affect your vision, your doctor may decide not to treat it. Often, doctors will not treat children with ptosis. Your child’s doctor will check his eyes regularly. You will probably treat amblyopia with drops, patches, or glasses. And he will look at the vision to see if your child needs surgery as he ages.
For adults, treatment usually means surgery. Your doctor can remove the extra skin and tuck in the muscle that lifts the lid. Or you can reattach and strengthen that muscle.
You may also be able to use glasses with a unique built-in crutch. Raise your eyelids so you can see better. That helps you avoid surgery.
How is it handled?
Ptosis can cause problems when driving, reading, or going up and downstairs. If that happens, see your doctor.
Treat any other eye problems that may cause more problems. Consider surgery if your doctor suggests it for vision loss caused by ptosis. For teens, surgery can improve not only vision but also self-esteem. Children with ptosis should see an eye doctor regularly.
