What is myopia, its burden and prevalence in India and worldwide?

Myopia: Definition, Burden, and Prevalence in India and Worldwide

Definition of Myopia

Myopia, also known as short-sightedness or near-sightedness, is a refractive error where distant objects appear blurry while near objects remain clear, primarily caused by excessive axial elongation of the eyeball. 1 It typically begins in childhood and can progress throughout adolescence and early adulthood.

Myopia is not merely a refractive error requiring correction but represents a true sight-threatening ocular condition that can lead to serious complications, especially in cases of high myopia (≤-6.0 diopters) 2, 3.

Global Prevalence and Burden

The global prevalence of myopia has reached epidemic proportions:

• Currently affects a significant portion of the world population
• Projected to affect approximately 50% of the world's population by 2050 4, 2
• East Asia has particularly high prevalence rates of 80-90% among young adults 3
• Approximately one-fifth of the myopic population has high myopia (≤-6.0 diopters) 3

The burden of myopia extends beyond vision correction needs:

• It is becoming the leading cause of irreversible blindness in East Asia 3
• High myopia significantly increases lifetime risk of vision-threatening complications including:
  • Retinal detachment
  • Choroidal neovascularization
  • Early cataracts
  • Glaucoma
  • Myopic maculopathy
  • Macular atrophy 4, 3

Prevalence in India

While the provided evidence doesn't specifically detail myopia prevalence in India, it can be understood within the context of global and Asian trends. India, as part of Asia, likely experiences significant myopia rates, though perhaps not as extreme as East Asian countries where prevalence reaches 80-90% in young adults.

Risk Factors and Contributing Factors

The increasing prevalence of myopia appears to be driven by both genetic and environmental factors:

• Decreased outdoor time and increased near work activities (particularly digital device use) 2
• Genetic predisposition interacting with environmental factors 3
• Earlier onset of myopia is associated with faster progression and greater risk of high myopia 3
• Hyperopia (≤0.5 diopters) is a predictor of future myopia development 3
• Non-ophthalmological factors such as body stature, sleep patterns, and nutritional status correlate with myopia progression in children and adolescents 2

Prevention and Management Strategies

Several effective interventions have been identified:

• Preventive measures:

  • Increased outdoor activity (minimum 2 hours daily) 2, 3
  • Decreased excessive near work, especially on digital devices 2

• Treatment approaches:

  • Optical correction: Defocus-incorporated multisegment spectacle lenses 2
  • Orthokeratology for corneal reshaping 2, 3
  • Pharmacological treatment: Low-concentration atropine (0.05%) eye drops 2, 3, 5

Public Health Implications

The rising prevalence of myopia represents a significant public health challenge:

• Early detection and intervention are crucial for effective myopia control 5
• Improved data collection using wearable technology and artificial intelligence may help in understanding risk factors and progression 1
• Enhanced public health strategies focusing on prevention and early detection are needed 1
• In children with high myopia, evaluation for syndromic myopia is important 5

The myopia epidemic requires coordinated efforts from governments and international eye health organizations to reduce its impact in coming decades 3.