Myopia (Nearsightedness)
A common refractive error where distant objects appear blurry while close objects remain clear, affecting nearly 30% of the global population
Quick Facts
- Type: Refractive Error
- ICD-10: H52.1
- Prevalence: 30% globally
- Treatable: Yes
Overview
Myopia, commonly known as nearsightedness or short-sightedness, is a refractive error of the eye where light focuses in front of the retina instead of directly on it. This causes distant objects to appear blurry while near objects remain clear. It's one of the most common vision problems worldwide, affecting approximately 2.6 billion people globally, with prevalence expected to reach nearly 5 billion by 2050.
In a myopic eye, the eyeball is typically too long from front to back, or the cornea (the clear front surface of the eye) has too much curvature. This altered shape prevents light from focusing properly on the retina, the light-sensitive tissue at the back of the eye. The degree of myopia is measured in diopters (D), with mild myopia ranging from -0.25D to -3.00D, moderate from -3.00D to -6.00D, and high myopia exceeding -6.00D.
Myopia typically develops in childhood and tends to progress until the late teens or early twenties when the eye stops growing. However, adult-onset myopia is becoming more common, particularly among those who perform extensive near work. While myopia is easily corrected with glasses, contact lenses, or surgery, high myopia increases the risk of serious eye conditions such as retinal detachment, glaucoma, and myopic maculopathy, making regular eye examinations crucial for early detection and management of potential complications.
Symptoms
Myopia symptoms vary in severity depending on the degree of nearsightedness and can affect daily activities and quality of life.
Primary Vision Symptoms
Associated Symptoms
- Eye pain or discomfort
- Headaches, especially after visual tasks
- Difficulty driving, especially at night
- Problems seeing classroom boards or presentations
- Sitting close to TV or computer screens
- Holding books very close when reading
- Not recognizing faces at a distance
- Poor performance in sports requiring distance vision
Symptoms in Children
- Consistently sitting too close to the TV
- Holding books or tablets very close to face
- Squinting or closing one eye to see
- Frequent eye rubbing
- Complaints of headaches or tired eyes
- Poor academic performance
- Lack of interest in distant activities
- Difficulty recognizing people from afar
Complications Symptoms
High myopia may lead to:
- Foreign body sensation
- Flashes of light (photopsia)
- Sudden increase in floaters
- Shadow or curtain over vision
- Distorted vision (metamorphopsia)
- Vision loss in severe cases
Causes
Myopia results from a complex interaction of genetic and environmental factors affecting eye growth and development.
Anatomical Causes
Axial Myopia (Most Common)
- Eyeball grows too long from front to back
- Light focuses in front of retina
- Usually develops during childhood growth
- Progressive during school years
Refractive Myopia
- Cornea too curved
- Lens too thick or wrongly positioned
- Normal eye length but excessive focusing power
- Less common than axial myopia
Genetic Factors
- Family history: 3x higher risk if one parent myopic
- Both parents myopic: 6x higher risk
- Multiple genes involved: Over 200 genetic variants identified
- Ethnic variations: Higher prevalence in East Asian populations
- Syndromic associations: Marfan syndrome, Stickler syndrome
Environmental Factors
Near Work
- Prolonged reading or screen time
- Close working distance
- Poor lighting conditions
- Lack of breaks during near tasks
- Early intensive education
Lifestyle Factors
- Limited outdoor time: Less than 2 hours daily
- Indoor activities: Excessive screen time
- Urban environment: Less exposure to natural light
- Diet: Some studies suggest nutritional links
Other Contributing Factors
- Premature birth
- Low birth weight
- Maternal smoking during pregnancy
- Certain medications (e.g., some glaucoma drops)
- Systemic conditions affecting connective tissue
Risk Factors
Multiple factors increase the likelihood of developing myopia or its progression:
Non-Modifiable Risk Factors
- Family history: Strongest predictor
- Ethnicity: Higher in East Asian populations (80-90%)
- Age of onset: Earlier onset leads to higher myopia
- Gender: Slightly higher in females
- Genetic syndromes: Down syndrome, Marfan syndrome
Modifiable Risk Factors
- Limited outdoor time: Major modifiable risk factor
- Excessive near work: Reading, screens, crafts
- Poor visual hygiene: Bad posture, poor lighting
- Urban living: Less natural light exposure
- Higher education level: More years of schooling
Environmental Factors
- Indoor-dominant lifestyle
- Early age of starting formal education
- Competitive academic environment
- Limited sports participation
- Year-round schooling
Modern Lifestyle Factors
- Digital device use from early age
- E-learning and remote education
- Gaming and entertainment screens
- Reduced outdoor play time
- Urbanization and apartment living
Diagnosis
Myopia is diagnosed through comprehensive eye examination using various tests to measure visual acuity and refractive error.
Vision Screening
Visual Acuity Test
- Snellen chart (20/20 measurement)
- Distance vision assessment
- Each eye tested separately
- With and without current correction
- Near vision also tested
Refraction Testing
Objective Refraction
- Autorefractor: Automated measurement
- Retinoscopy: Manual assessment with light
- Determines approximate prescription
- Quick and non-invasive
Subjective Refraction
- Phoropter or trial frame testing
- Patient feedback on lens choices
- "Which is better, 1 or 2?"
- Fine-tunes prescription
- Determines best corrected vision
Additional Testing
Biometry
- Axial length measurement: Eye length assessment
- Corneal topography: Corneal shape mapping
- Important for: Monitoring progression
Eye Health Examination
- Slit lamp examination: Front of eye
- Dilated fundus exam: Retinal evaluation
- Intraocular pressure: Glaucoma screening
- Peripheral retinal exam: For high myopes
Specialized Tests for High Myopia
- OCT (Optical Coherence Tomography): Retinal layers
- Visual field testing: Peripheral vision
- Fundus photography: Documentation
- B-scan ultrasound: If media opacity
Treatment Options
Myopia treatment focuses on correcting vision and, in children, slowing progression to prevent high myopia.
Optical Correction
Eyeglasses
- Single vision lenses: Standard correction
- High-index lenses: Thinner for high prescriptions
- Anti-reflective coating: Reduces glare
- Photochromic lenses: Darken in sunlight
- Blue light filters: For digital device use
Contact Lenses
- Soft contact lenses: Daily, weekly, monthly
- Gas permeable (GP) lenses: Sharp vision
- Extended wear options: Continuous use
- Toric lenses: If astigmatism present
- Multifocal contacts: For presbyopia
Myopia Control Methods
Pharmaceutical
- Atropine eye drops: Low-dose (0.01-0.05%)
- Slows progression: 30-60% reduction
- Daily application: Usually at bedtime
- Minimal side effects: At low concentrations
Optical Interventions
- Orthokeratology (Ortho-K): Overnight corneal reshaping
- Multifocal contact lenses: Center-distance design
- Peripheral defocus glasses: DIMS, H.A.L.T. technology
- Progressive addition lenses: For specific cases
Surgical Options
Laser Vision Correction
- LASIK: Most common, flap-based
- PRK: Surface ablation, no flap
- SMILE: Small incision lenticule extraction
- Requirements: Stable prescription, age 18+
- Limitations: Not suitable for very high myopia
Lens-Based Surgery
- Phakic IOLs: Implantable contact lens
- Clear lens extraction: For extreme myopia
- Higher risk: Intraocular procedures
- Better for: Very high prescriptions
Lifestyle Management
- Increase outdoor time (2+ hours daily)
- Follow 20-20-20 rule for near work
- Maintain proper reading distance (30cm+)
- Ensure adequate lighting
- Regular eye examinations
- Monitor children's vision habits
Prevention
While genetic factors cannot be changed, several strategies may help prevent or slow myopia development and progression:
Outdoor Time
- Minimum 2 hours daily: Protective effect proven
- Natural light exposure: Key factor, not just exercise
- School programs: Outdoor classes and breaks
- Weekend activities: Parks, sports, gardening
- Year-round benefit: Even cloudy days help
Visual Hygiene
- 20-20-20 rule: Every 20 minutes, look 20 feet away for 20 seconds
- Proper distance: Books/screens at least 30cm away
- Good posture: Upright position while reading
- Adequate lighting: Avoid reading in dim light
- Limited continuous near work: Take regular breaks
Screen Time Management
- Limit recreational screen time
- No screens for children under 2
- Maximum 1-2 hours for ages 2-5
- Balance with outdoor activities
- Maintain proper viewing distance
Early Detection
- Regular eye exams from age 3
- Annual checks for at-risk children
- School vision screenings
- Monitor family history
- Early intervention when detected
When to See a Doctor
Regular eye examinations are crucial for detecting and managing myopia, especially in children:
Routine Eye Exams
- First exam: By age 3 or earlier if concerns
- School-age children: Every 1-2 years
- Myopic children: Every 6-12 months
- Adults: Every 2 years or as recommended
- High myopia: Annual comprehensive exams
Seek Immediate Care For
- Sudden vision loss or significant change
- Flashes of light or shower of floaters
- Curtain or shadow over vision
- Eye pain with vision changes
- Halos around lights
- Eye injury or trauma
Schedule an Appointment For
- Difficulty seeing distant objects
- Squinting or eye strain
- Frequent headaches
- Child sitting close to TV/books
- Declining school performance
- Family history of myopia
Frequently Asked Questions
Currently, there is no cure for myopia. However, it can be effectively corrected with glasses, contact lenses, or refractive surgery. In children, various treatments can slow its progression, potentially preventing high myopia and associated complications. Research into reversing myopia is ongoing.
Myopia typically progresses during childhood and adolescence, stabilizing in the late teens or early twenties. The rate of progression varies, but early onset usually leads to higher final prescriptions. Myopia control treatments can slow progression by 30-60%, significantly reducing the risk of high myopia.
No, wearing properly prescribed glasses does not make myopia worse. In fact, not wearing needed correction can cause eye strain and may affect visual development in children. Under-correction was once thought to slow progression but research shows it may actually accelerate it.
LASIK is generally safe and effective for suitable candidates with stable prescriptions. Success rates exceed 95% for achieving 20/40 vision or better. However, it's not appropriate for everyone, particularly those under 18, with unstable prescriptions, very high myopia, or certain corneal conditions.
Yes, numerous studies show that spending at least 2 hours daily outdoors can reduce myopia risk by up to 50%. The protective effect appears related to bright natural light exposure rather than physical activity itself. This is one of the most effective preventive measures currently known.
References
- Holden BA, Fricke TR, Wilson DA, et al. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology. 2016;123(5):1036-1042.
- Wildsoet CF, Chia A, Cho P, et al. IMI - Interventions for Controlling Myopia Onset and Progression Report. Invest Ophthalmol Vis Sci. 2019;60(3):M106-M131.
- Morgan IG, Wu PC, Ostrin LA, et al. IMI Risk Factors for Myopia. Invest Ophthalmol Vis Sci. 2021;62(5):3.
- Wolffsohn JS, Flitcroft DI, Gifford KL, et al. IMI - Myopia Control Reports Overview and Introduction. Invest Ophthalmol Vis Sci. 2019;60(3):M1-M19.
- American Academy of Ophthalmology. Myopia (Nearsightedness). EyeSmart. 2023.