What are the other Names for this Condition? (Also known as/Synonyms)

• ASK (Aniseikonia)

What is Aniseikonia? (Definition/Background Information)

• Aniseikonia (ASK) is an eye condition that is characterized by significant differences in perceived object sizes between the two eyes. This may occur following an eye condition or due to incorrect prescription to correct refractive errors (such as wearing wrong eyeglasses)
• Aniseikonia can be easily managed through wearing suitable glasses or contact lenses. If left untreated, it may result in severe eye strain, headaches, reading difficulties, and visual spatial perception issues

Who gets Aniseikonia? (Age and Sex Distribution)

• Individuals of any age category of both male and female gender may be affected
• Worldwide, individuals of all races and ethnicity are prone to developing the condition

What are the Risk Factors for Aniseikonia? (Predisposing Factors)

The risk factors for Aniseikonia may include:

• Unilateral aphakia: The absence of eye lens (from one eye) either due to a congenital condition or following its surgical removal
• Anisometropia: A condition when the eyes have different refractive powers
• Anisophoria: Eye muscle imbalance causing abnormality in viewing horizontal visual plane
• Incorrectly prescribed eyeglasses or contact lenses for shortsightedness, longsightedness, or other refractive errors

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Aniseikonia? (Etiology)

Aniseikonia develops from natural causes, such as aphakia or anisometropia, or secondary to the use of poorly prescribed eyeglasses or contact lenses.

There are two types of Aniseikonia:

• Optically-induced Aniseikonia - when it occurs from refractive errors and related surgery, cataract surgery and lens implantation, or from absence of the lens (congenital or acquired)
• Retinally-induced Aniseikonia - when the retina is damaged or stretched such as due to retinal detachment, retinal tears, or macular anomalies

It is important to note that the human eye can tolerate small amounts of Aniseikonia (up to 7%), according to medical experts. Thus, individuals with very mild forms of the condition do not have abnormal vision problems.

What are the Signs and Symptoms of Aniseikonia?

The signs and symptoms of Aniseikonia may differ from one individual to another. It may be mild or severe, depending on several factors such as the underlying causative condition and the magnitude of the refractive error.

The commonly observed signs and symptoms include:

• Difficulty in perceiving space; disorientation
• Eye strain and fatigue
• Needing to strain to read or perform simple visual tasks
• Double vision
• Headaches
• Dizziness

Associated signs and symptoms of the underlying condition/disorder, if any, may also be observed.

How is Aniseikonia Diagnosed?

Aniseikonia may be diagnosed by the following observations and tests:

• Physical examination and medical history evaluation
• Assessment of signs and symptoms
• General eye exam
• Fundoscopic (ophthalmoscopic) examination by an eye specialist, who examines the back part of the eye (or the fundus)
• Visual acuity test using a special and standardized test chart (Snellen chart)
• Slit-lamp examination
• Visual evoked potential (VEP) test
• Fundus fluorescein angiography
• Optical coherence tomography (OCT) of eye
• Imaging studies including CT and MRI scans of the head and neck region, if needed

Additional tests and procedures to diagnose the underlying causative condition may be needed.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Aniseikonia?

The complications of Aniseikonia may include:

• Emotional stress
• Poor vision
• Decreased quality of life

Complications arising from the underlying/associated condition, if any present, may be noted.

How is Aniseikonia Treated?

The treatment of Aniseikonia depends on the extent of the condition, the presenting signs and symptoms, and the underlying causative factor.

• Generally, the healthcare provider may recommend suitable eyeglasses or contact lenses
• In rare cases, a correction through refractive corneal surgery may be needed
• The treatment measures include treating the symptoms and managing the underlying condition/disorder

How can Aniseikonia be Prevented?

It may be difficult to prevent some cases of Aniseikonia. However, the following factors may help reduce one’s risk for developing the same:

• Having regular eye checkup at an eye clinic of repute
• Wearing glasses regularly (for the prescribed condition)
• Availing early and adequate treatment of any eye health issues

What is the Prognosis of Aniseikonia? (Outcomes/Resolutions)

The overall prognosis of Aniseikonia depends on the severity of the condition and underlying causative condition. However, in a vast majority of cases, Aniseikonia can be corrected through the use of appropriate spectacles or contact lenses.

Additional and Relevant Useful Information for Aniseikonia:

Please visit our Eye & Vision Health Center for more physician-approved health information:

https://www.dovemed.com/health-topics/vision-center/