Amblyopia

Amblyopia is the lack of proper vision development in early life that causes long-term decreased vision. If light cannot travel clearly and accurately to the retina in the back of the eye, vision does not develop properly. Amblyopia more commonly occurs in one eye (unilateral), but can occur in both eyes (bilateral) and usually develops between birth and age 7.^{1, 2}Amblyopia is the leading cause of decreased visual acuity in children.² Amblyopia is diagnosed when visual acuity is 20/40 or worse and there are no structural issues causing this decreased vision. Amblyopia affects approximately 3% of the population.³ 

Deprivation amblyopia: decreased vision as a result of a blockade in vision; can be caused by ptosis (eyelid drooping in front of where we see), congenital cataract (opacification in the lens of the eye blocking light front reaching the photoreceptors of the retina). 

Refractive amblyopia: decreased vision from uncorrected refractive error (not wearing glasses or contact lenses) in one (anisometropic amblyopia) or both eyes (isoametropic amblyopia). 

Strabismic amblyopia: eye turn inward or outward preventing light from hitting the center of the retina, called the macula; more severe if the eye turn is constant vs. intermittent. 

Reverse amblyopia: occurs when the stronger eye is blocked to an extent that causes amblyopia in that eye.⁴ 

Signs and symptoms of Amblyopia: 

• One or both eyes drifting inward or outward 
• Squinting 
• Head tilt or turn 
• Lack of depth perception (3D vision) 
• Closing one eye when focusing² 

Amblyopia is diagnosed in an eye exam with an eye care professional. The doctor will assess the patient’s refractive error (glasses prescription), eye alignment (determining if an eye turn is present), and if something is blocking proper vision (cataract, ptosis, etc.).   

Glasses or contact lenses: correcting the refractive error to increase clarity of vision. 

Eye patch: patch over stronger eye, usually for a few hours per day, to force the weaker eye to see more clearly. 

Pharmacological therapy: atropine drops in stronger eye to blur vision in an attempt to stimulate the weaker eye. 

Bangerter filter: blurring filter that goes on the lens of the stronger eye to stimulate the weaker eye to see more clearly.  

Cataract surgery: if cataracts are causing decreased vision and lack of proper vision development, cataract surgery is performed to remove the cloudy or opacified lens.  

Strabismus surgery: if an eye turn, or strabismus, is causing a lack of vision development, eye muscle surgery can be performed to correct the eye turn. 

Eyelid surgery: if a drooping eyelid, or ptosis, is causing a block of vision development, a surgery can be performed to lift the eyelid so the patient can see out of the affected eye(s).⁵ 

Eye examinations as recommended by your eye care provider, including at a young age, to determine if amblyopia is present. The earlier decreased visual acuity is determined and the sooner management is implemented, the better the prognosis for improved vision. 

1. Hoyt, C. (2000, September 1). Amblyopia. British Journal of Ophthalmology. Retrieved January 6, 2022, from https://bjo.bmj.com/content/84/9/944 
2. Lazy eye (amblyopia) – Symptoms and causes. (2021, August 14). Mayo Clinic. Retrieved January 6, 2022, from https://www.mayoclinic.org/diseases-conditions/lazy-eye/symptoms-causes/syc-20352391 
3. Wong, A. M. (2013). Amblyopia (lazy eye) in children. Canadian Medical Association Journal, 186(4), 292. https://doi.org/10.1503/cmaj.130666 
4. Types of Amblyopia. (2015, October 21). American Academy of Ophthalmology. Retrieved January 6, 2022, from https://www.aao.org/disease-review/types-of-amblyopia 
5. Lazy eye (amblyopia) – Diagnosis and treatment. (2021, August 14). Mayo Clinic. Retrieved January 6, 2022, from https://www.mayoclinic.org/diseases-conditions/lazy-eye/diagnosis-treatment/drc-20352396