Author: Vanessa Mora
Editor: Nicholas Jo
Overview
Amblyopia, also known as lazy eye, is a form of visual impairment where there is a decrease in vision resulting from abnormal visual development in infancy to early childhood (Blair et al., 2020). Amblyopia ranges from mild vision loss (20/25) to legal blindness (20/200 and worse); the brain focuses on one eye more than the other and hence leads to its blindness unless the child or young adult receives proper treatment (Chen & Cotter, 2016). Amblyopia may be extremely dangerous since it involves eye symptoms that are hard to detect during infancy (Holmes & Clarke, 2006).
Epidemiology
Amblyopia affects approximately 1%–5% of the population worldwide, affecting nearly 15 million children. More than half of these cases will not be identified before a child reaches school age since the symptoms are difficult to diagnose (Jefferis & Connor, 2015).
Etiology
Normal visual stimulation is essential for the development of neurons in the brain. Amblyopia develops because of abnormal visual stimulation and a large discrepancy between the prescription between the two eyes. Abnormalities in spatial vision/interaction, stereoscopic activity, and binocular summation may prevent high-resolution images on each eye’s retina, such as anisometropia, strabismus, cataracts, refractive errors, droopy eyelids, or a combination of these factors may lead to Amblyopia (Blair, 2020).
Symptoms
Some common signs and symptoms of Amblyopia include:
- Abnormal contour interaction,
- Abnormal eye movements (inward or outward),
- Head tilting,
- Positional uncertainty,
- Reduced contrast sensitivity,
- Spatial distortion,
- Squinting and/or eye shutting (Chen & Cotter, 2016)
If left untreated, Amblyopia may lead to permanent vision loss (Blair, 2020).
Risk Factors
One of the risk factors that increase the likelihood of acquiring Amblyopia is having unequal prescriptions between both eyes (anisometropia), being farsighted (hyperopic) or nearsighted (myopic) and having torticollis. Being born prematurely or having a family history of Amblyopia may increase the likelihood (Birch,2013).
Diagnosis
Clinical Features
After a thorough physical examination is performed by acquiring the child’s medical history, ocular history, pupil examination and external inspection of the eyelids, a physician may decide to conduct further tests to determine if the patient suffers from Amblyopia (Bradfield, 2013).
For infants and children, red reflex testing is used in detecting the risk factors for Amblyopia, such as a cataract, refractive error, and retinal pathology. Consistent non-cooperativity after the placement of an adhesive patch on one eye may hint towards Amblyopia (Jefferis & Connor, 2015).
The physician may also perform visual testing for children three years or older with an eye chart based test. The charts are held at a proper testing distance of 10 or 20 feet (approximately 3 or 6 m). If their vision is less than 20/32 in either eye, the patient may be referred to a pediatric ophthalmologist (Bradfield, 2013).
Treatment Protocol
The management of Amblyopia consists of 2 phases:
- Phase 1: Optical treatment
- Phase 2: Patching or atropine (Jefferis & Connor, 2015).
Pharmacological Treatment Protocol
Atropine drops are an alternative form of patching (Tailor & Greenwood, 2016). The drops are used in the non-amblyopic eye. They cause blurring by pupil dilatation and loss of accommodation to force reliance on the amblyopic eye (Birch, 2013).
Non-Pharmacological Treatment Protocol
Children with Amblyopia that also have strabismus, anisometropia, or a mixture of factors may be prescribed optimum refraction as priority treatment. If there is no gain in vision after three months, occlusion therapy will be started. Occlusion therapy uses an eye patch to cover the non-amblyopic eye for 2-6 hours each day with ultimately a total of 150- 200 hours (Jefferis & Connor, 2015).
Articles on Misdiagnosis
Arora, R., & M. Lohchab. (2019). Pediatric keratoconus misdiagnosed as meridional amblyopia. Indian Journal of Ophthalmology, 67(4), 551-552. DOI: 10.4103/ijo.IJO_1496_18.
Lim, C.H., & S.R. Bae. (2002). A case of DeMorsier syndrome misdiagnosed as amblyopia. Journal of the Korean Ophthalmol Society, 43(7), 1335-1339. Retrieved from https://www.koreamed.org/SearchBasic.php?RID=2206128.
Kyung, S.E., & M. Lee. (2012). Foveal retinoschisis misdiagnosed as bilateral amblyopia. Int Ophthalmol, 32, 595-598. DOI: 10.1007/s10792-012-9600-y.
References
Blair, K., Cibis, G., & Gulani, A. C. (2020). Amblyopia. In StatPearls. StatPearls Publishing. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK430890/.
Birch, E. E. (2013). Amblyopia and binocular vision. Progress in Retinal and Eye Research, 33, 67-84. DOI: 10.1016/j.preteyeres.2012.11.001.
Chen, Angela M, and Susan A Cotter. “The Amblyopia Treatment Studies: Implications for Clinical Practice.” Advances in ophthalmology and optometry vol. 1,1 (2016): 287-305. DOI: 10.1016/j.yaoo.2016.03.007.
Holmes, J. M., & Clarke, M. P. (2006). Amblyopia. The Lancet, 367(9519), 1343-1351. DOI: 10.1016/S0140-6736(06)68581-4.
Jefferis, J. M., Connor, A. J., & Clarke, M. P. (2015). Amblyopia. Bmj, 351. DOI: 10.1136/bmj.h5811.
Tailor, V., Bossi, M., Greenwood, J. A., & Dahlmann-Noor, A. (2016). Childhood amblyopia: current management and new trends. British medical bulletin, 119(1), 75–86. DOI: 10.1093/bmb/ldw030.
