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Amblyopia

Disease Details

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Description: Amblyopia, often called "lazy eye," is a vision development disorder where an eye fails to achieve normal visual acuity, usually due to strabismus, anisometropia, or deprivation during early childhood.
Type: Amblyopia, often referred to as "lazy eye," is not classified as a single disease type but rather as a developmental visual disorder. It typically occurs when the brain and one eye do not work together properly, resulting in decreased vision in the affected eye.

Regarding genetic transmission, amblyopia is not directly inherited in a simple Mendelian fashion. However, genetic factors can contribute to its development, often in conjunction with environmental factors. Conditions leading to amblyopia, such as strabismus (misaligned eyes) or significant refractive errors, can have genetic components, suggesting a multifactorial inheritance pattern.
Signs And Symptoms: Many people with amblyopia, especially those who only have a mild form, are not aware they have the condition until tested at older ages, since the vision in their stronger eye is normal. People with amblyopia typically have poor stereo vision, since it requires both eyes. They further may have, on the affected eye, poor pattern recognition, poor visual acuity, and low sensitivity to contrast and motion.Amblyopia is characterized by several functional abnormalities in spatial vision, including reductions in visual acuity, contrast sensitivity function, and vernier acuity, as well as spatial distortion, abnormal spatial interactions, and impaired contour detection. In addition, individuals with amblyopia have binocular abnormalities such as impaired stereoacuity (stereoscopic acuity) and abnormal binocular summation. Also, central vision in amblyopes is more crowded than central vision in normal observers.These deficits are usually specific to the amblyopic eye. Subclinical deficits of the "better" eye have also been demonstrated.People with amblyopia also have problems of binocular vision such as limited stereoscopic depth perception and usually have difficulty seeing the three-dimensional images in hidden stereoscopic displays such as autostereograms. Perception of depth, from monocular cues such as size, perspective, and motion parallax remains normal.
Prognosis: Amblyopia, also known as lazy eye, has a prognosis that significantly depends on early detection and treatment. Early and effective intervention, particularly before age 7, generally leads to better outcomes. Treatment methods include corrective glasses, patching the stronger eye, or atropine drops to blur vision in the stronger eye, thereby stimulating use of the weaker eye. If addressed early, many children can recover most, if not all, of their vision. However, if left untreated past a critical developmental period, amblyopia may lead to persistent vision impairment.
Onset: Amblyopia, often referred to as "lazy eye," typically has its onset in early childhood, usually between birth and 7 years of age. Early detection and treatment are crucial for the best outcomes.
Prevalence: Amblyopia, commonly known as "lazy eye," affects approximately 2-3% of the population.
Epidemiology: Amblyopia occurs in 2–5% of the population in Western countries. In the UK, 90% of visual health appointments in the child concern amblyopia.Depending on the chosen criterion for diagnosis, 1–4% of the children have amblyopia.
Intractability: Amblyopia, commonly known as "lazy eye," is not necessarily intractable. Early detection and treatment significantly improve outcomes, especially in children. Treatments include patching the stronger eye, corrective glasses, and vision therapy. Although more challenging, treatment in older children and adults can still yield improvements in some cases. Thus, while amblyopia can be persistent if untreated, it is not intractable with appropriate and timely interventions.
Disease Severity: For amblyopia, also known as "lazy eye":

- **Disease Severity**: Amblyopia can range from mild to severe. In mild cases, the vision in the affected eye might be slightly blurred. In severe cases, vision can be significantly impaired in the affected eye.

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Healthcare Professionals: Disease Ontology ID - DOID:10376
Pathophysiology: Amblyopia is a developmental problem in the brain, not any intrinsic, organic neurological problem in the eyeball (although organic problems can lead to amblyopia which can continue to exist after the organic problem has resolved by medical intervention).
The part of the brain receiving images from the affected eye is not stimulated properly and does not develop to its full visual potential. This has been confirmed by direct brain examination. David H. Hubel and Torsten Wiesel won the Nobel Prize in Physiology or Medicine in 1981 for their work in showing the extent of the damage to ocular dominance columns produced in kittens by sufficient visual deprivation during the so-called "critical period". The maximum "critical period" in humans is from birth to two years old.
Carrier Status: Amblyopia, commonly known as "lazy eye," is not a condition that involves carrier status as it is not a genetic disorder in the typical sense. Amblyopia primarily results from developmental issues in the brain and eye relationship, often due to strabismus (misalignment of the eyes), significant differences in prescription strengths between the two eyes, cataracts, or other ocular conditions. Early diagnosis and treatment are crucial to prevent long-term vision issues.
Mechanism: Amblyopia, often known as "lazy eye," is a neurodevelopmental disorder that results in decreased vision in one eye due to abnormal visual experience during early childhood. Understanding its mechanism and molecular underpinnings involves several key factors:

**Mechanism:**
1. **Interruption of Normal Visual Experience**: The primary cause is an abnormal visual experience during a critical period of visual development in early childhood. This can be due to strabismus (misaligned eyes), anisometropia (significant difference in prescription between the two eyes), or deprivation (such as congenital cataract).
2. **Suppression**: The brain tends to suppress the input from the weaker eye to prevent double vision, leading to neural changes that favor the stronger eye.
3. **Cortical Changes**: There are functional and structural changes in the visual cortex, specifically in the neurons that process visual information from the weaker eye.

**Molecular Mechanisms:**
1. **Synaptic Plasticity**: Alterations in synaptic strength and plasticity within the visual cortex are crucial. This involves changes in synaptic proteins and receptors, such as NMDA and AMPA receptors, affecting how visual information is processed.
2. **Neurotransmitter Systems**: Dopaminergic, glutamatergic, and GABAergic systems play significant roles. Imbalance in excitation and inhibition ratios due to changes in these neurotransmitter systems influences cortical plasticity and visual processing.
3. **Neurotrophic Factors**: Molecules like Brain-Derived Neurotrophic Factor (BDNF) are vital in maintaining synaptic connections and plasticity. Alterations in the levels or activity of such neurotrophic factors can impact neuronal development and visual function.
4. **Gene Expression**: Altered expression of genes involved in synaptic function and plasticity, such as those coding for synaptic proteins and receptors, can affect neuronal connectivity and visual processing.
5. **Calcium Signaling**: Calcium signaling pathways, crucial for synaptic plasticity and neuronal health, also play a role. Disruptions in calcium homeostasis can lead to altered synaptic function and plasticity.

Collectively, the interplay between these factors leads to the diminished visual acuity characteristic of amblyopia.
Treatment: Treatment of strabismic or anisometropic amblyopia consists of correcting the optical deficit (wearing the necessary spectacle prescription) and often forcing use of the amblyopic eye, by patching the good eye, or instilling topical atropine in the good eye, or both.: 130 Atropine appears to result in similar outcomes to patching. If there is overpatching or overpenalizing the good eye when treating amblyopia, "reverse amblyopia" can result. Eye patching is usually done on a part-time schedule of about 4–6 hours a day. Treatment is continued as long as vision improves. It is not worthwhile continuing to patch for more than 6 months if no improvement continues.Deprivation amblyopia is treated by removing the opacity as soon as possible followed by patching or penalizing the good eye to encourage the use of the amblyopic eye. The earlier the treatment is initiated, the easier and faster the treatment is and the less psychologically damaging. Also, the chance of achieving 20/20 vision is greater if treatment is initiated early.One of the German public health insurance providers, Barmer, has changed its policy to cover, as of 1 April 2014, the cost of software for amblyopic children whose condition did not improve through patching. The app offers dedicated eye exercises that the patient performs while wearing an eyepatch.Evidence for vision therapy is unclear as of 2011.
Compassionate Use Treatment: Amblyopia, commonly known as "lazy eye," is typically treated through approaches such as patching the stronger eye, atropine eye drops to temporarily blur vision in the strong eye, corrective lenses, or vision therapy. In terms of compassionate use or experimental treatments:

1. **Compassionate Use Treatment**:
- **RevitalVision**: A computer-based vision training program that has been made available under compassionate use in some cases. It is designed to improve visual acuity and contrast sensitivity.

2. **Off-label or Experimental Treatments**:
- **Oral Levodopa**: While primarily used for Parkinson's disease, some studies have investigated its efficacy in improving visual outcomes in amblyopia.
- **Transcranial Magnetic Stimulation (TMS)**: An emerging technology that uses magnetic fields to stimulate nerve cells in the brain and has been explored for treating amblyopia.
- **Binocular Treatment Approaches**: These include interactive video games and virtual reality systems designed to rebalance the use of both eyes by encouraging binocular vision.

These treatments are still under investigation, and their efficacy may vary. Always consult with a healthcare professional for personalized medical advice.
Lifestyle Recommendations: For amblyopia, lifestyle recommendations focus on promoting eye health and visual development:

1. **Early Detection and Treatment**: Ensure regular eye check-ups, especially for children, to detect and treat amblyopia early.
2. **Follow Treatment Plans**: Adhere to treatments such as patching the stronger eye, atropine eye drops, or corrective eyewear as prescribed by an eye specialist.
3. **Vision Therapy**: Engage in vision therapy exercises to strengthen the weaker eye. These therapies can include activities like puzzles, video games, or reading.
4. **Limit Screen Time**: Manage screen time to avoid excessive strain on the eyes, promoting more balanced visual activities.
5. **Healthy Diet**: Consume a diet rich in vitamins and nutrients beneficial for eye health, including leafy greens, fish rich in omega-3 fatty acids, and fruits high in vitamin C.
6. **Regular Breaks**: Take frequent breaks during tasks that involve intense visual focus to reduce eye strain.
7. **Protect Eyes**: Use protective eyewear during activities that pose a risk of injury to the eyes.
Medication: Medication typically isn't used to treat amblyopia. The primary treatments for amblyopia involve correcting the underlying visual defect or encouraging the use of the weaker eye. Common interventions include prescribing corrective glasses or contact lenses, patching the stronger eye to force the weaker eye to work harder, and using atropine eye drops to blur vision in the stronger eye, thus stimulating the weaker eye. Early diagnosis and treatment are crucial for the best outcomes.
Repurposable Drugs: There are currently no widely accepted repurposable drugs specifically for the treatment of amblyopia. The condition is typically managed through methods such as patching the stronger eye, atropine drops to blur vision in the stronger eye, and vision therapy exercises. Recent research has been exploring the potential of repurposing drugs used in other conditions, such as antidepressants, to enhance neural plasticity, but these approaches are still experimental. Always consult medical professionals for the most current treatment options.
Metabolites: Amblyopia, often referred to as "lazy eye," does not have specific metabolites directly associated with its development or progression as it is primarily a developmental visual disorder. Amblyopia arises from poor visual experience during early childhood that leads to abnormal visual development.

However, in broader terms, normal metabolic function is essential for overall eye and brain health, which can indirectly influence visual development. Proper nutrition that supports metabolic health includes:

- Omega-3 fatty acids for retinal health
- Antioxidants (such as vitamins C and E) to protect retinal cells
- Vitamins, such as vitamin A, crucial for vision

Deficiencies in these components can affect visual health but aren't directly linked to amblyopia. Amblyopia treatment focuses on correcting vision issues with glasses, patching the stronger eye, and vision therapy exercises.
Nutraceuticals: Nutraceuticals have shown some promise in supporting eye health, which might indirectly benefit conditions like amblyopia, although they are not a primary treatment. There is no conclusive evidence that nutraceuticals alone can treat amblyopia, which usually requires interventions such as corrective lenses, patching, or vision therapy.

Nanotechnology, while still a developing field in ophthalmology, holds potential for delivering targeted therapies more effectively. For amblyopia, research is ongoing to explore how nanomedicine could improve treatment outcomes, possibly through more efficient drug delivery systems or novel therapeutic approaches.

At present, standard treatments remain the most reliable approach for managing amblyopia.
Peptides: Peptides are short chains of amino acids that can influence various biological functions, including processes involved in vision and neural development. Research is ongoing to explore their potential therapeutic use in treating amblyopia, often known as "lazy eye."

Nanotechnology (nan) refers to manipulating matter on an atomic or molecular scale, typically less than 100 nanometers. In the context of amblyopia, nanotechnology could contribute to innovative treatments, such as targeted drug delivery systems or advanced imaging techniques to better understand and treat the condition. However, these applications are still largely in the research and development stages.