Lazy Eye: Causes, symptoms, prevention and treatments
A School bus driver going through an eye test during a medical camp for school bus drivers within Nairobi Metropolitan at Parklands Primary School, Nairobi on March 2, 2024. Photo Bonface Bogita
What you need to know:
- Amblyopia, commonly known as "lazy eye," is a vision development disorder where one eye fails to achieve normal visual acuity, even with the use of corrective lenses
- It occurs when the brain favours one eye over the other during the critical period of visual development, typically within the first seven years of life
Amblyopia, commonly known as "lazy eye," is a vision development disorder where one eye fails to achieve normal visual acuity, even with the use of corrective lenses. This condition is the leading cause of vision impairment in children and affects approximately 2-3 per cent of the population globally. Amblyopia is not caused by any structural problem with the eye, but rather by improper visual development during childhood, which leads to a decrease in vision.
Amblyopia occurs when the brain favours one eye over the other during the critical period of visual development, typically within the first seven years of life. If one eye sends poor or insufficient visual signals, the brain suppresses the input from that eye to focus on the stronger eye, which leads to underdeveloped vision in the weaker eye. The brain learns to rely predominantly on the stronger eye, causing the weaker eye to become functionally "lazy."
Causes of Amblyopia
Strabismic Amblyopia: This is the most common form of amblyopia and occurs when there is an eye misalignment, such as in strabismus (crossed eyes or eye turn). When the eyes are misaligned, the brain may receive two conflicting images.
Refractive Amblyopia: This type is caused by significant differences in the refractive errors between the two eyes. The brain may ignore the image from the eye with the stronger refractive error, leading to poor visual development in that eye.
Deprivation Amblyopia: This form occurs when something impairs the normal development of vision in one eye, such as a cataract or ptosis (drooping eyelid).
Diagnostic Methods
Diagnosing amblyopia typically begins with a comprehensive eye examination. Early detection is critical, as treatment is most effective during the critical period of visual development. Diagnosis methodology includes:
Visual Acuity Testing: This involves checking how well each eye can see letters or symbols at a distance, with and without corrective lenses.
Cover-Uncover Test: This test is used to detect strabismus, a common cause of amblyopia.
Retinoscopy: A light is shined into the eyes to assess how the retina reacts, helping to detect refractive errors that may contribute to amblyopia.
Treatment Options
The primary goal is to stimulate the weaker eye and encourage the brain to utilize it more effectively.
Corrective Lenses: For refractive amblyopia, glasses or contact lenses can correct vision problems and help provide clear visual input to the brain
Occlusion Therapy (Eye Patching): Patching the stronger eye to force the weaker eye to work harder. This can significantly improve visual acuity in the affected eye.
Vision Therapy: Specialized exercises, often supervised by an optometrist, can help improve the coordination and function of the eyes and brain. These exercises may include activities that promote focusing, eye tracking, and depth perception.
Surgery: In cases of strabismus or other structural abnormalities, surgery may be necessary to correct eye alignment or remove cataracts, thus improving visual input from the affected eye.
Challenges in Treatment
Despite the effectiveness of treatment, amblyopia remains underdiagnosed, especially in cases that do not present obvious symptoms like misalignment or squinting. Many children with amblyopia do not exhibit noticeable signs, which is why routine eye exams are critical for early detection.
Another challenge is patient compliance. Treatments like eye patching can be difficult for children to tolerate, leading to inconsistent use and suboptimal results. Parents and caregivers must be vigilant in ensuring that children follow the prescribed regimen for maximum benefit.
Amblyopia is a common yet treatable condition, and early intervention plays a crucial role in improving visual outcomes. Understanding the causes, diagnostic methods, and available treatments can help patients with this condition. With appropriate treatment, children with amblyopia can achieve near-normal vision, allowing them to lead healthy, active lives. However, challenges such as early detection, compliance with treatment, and long-term follow-up care remain crucial factors in optimizing outcomes.
Correct diagnosis and adequate treatment impact directly on the life of the child and therefore these tests have to be carried out by a professional optometrist complemented with a robust follow-up program.
Murtaza Somji is a Senior Optometrist at Eyestyle Opticians