Most common refractive error in india
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most common refractive error prevalence India myopia hyperopia
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The retrieved result covers US data. I'll supplement with my own knowledge on India-specific epidemiology.
Most Common Refractive Error in India
Myopia (nearsightedness) is the most common refractive error in India, followed by astigmatism and hyperopia.
Key Epidemiological Data for India
| Refractive Error | Prevalence (India) | Notes |
|---|---|---|
| Myopia | ~13–19% (adults); higher in urban youth | Most common overall |
| Hyperopia | ~8–9% | More common in older adults |
| Astigmatism | ~10–15% | Often co-exists with myopia |
| Presbyopia | Very common (>40 yrs) | Affects virtually all adults over 45 |
Highlights
- Myopia is the leading refractive error and a major cause of preventable visual impairment in India. Urban populations and school-aged children show the highest rates, driven by increased near-work and reduced outdoor activity.
- The India Myopia Study and surveys under the National Programme for Control of Blindness (NPCB) consistently identify uncorrected refractive error — predominantly myopia — as the second leading cause of blindness in India after cataract.
- Hyperopia is more prevalent in rural populations and older age groups.
- Astigmatism frequently accompanies myopia and is underdiagnosed in rural settings.
- Presbyopia is extremely prevalent given India's large aging population, though it is often considered separately from "refractive error" in epidemiological studies.
Urban vs. Rural Divide
- Urban children: Myopia prevalence can be as high as 21–30% in school-going children in metro cities (Mumbai, Delhi, Chennai), attributed to screen time and limited outdoor exposure.
- Rural children: Lower myopia rates (~4–7%) but higher rates of uncorrected hyperopia and astigmatism due to lack of access to eye care.
Public Health Significance
Uncorrected refractive error is estimated to affect over 100 million Indians, making it a major public health priority. The NPCB and Vision 2020: The Right to Sight initiative have focused heavily on refractive error correction through school eye screening programs and subsidized spectacles.
Bottom line: Myopia is the most common refractive error in India, especially in younger and urban populations. Astigmatism is a close second, and hyperopia becomes increasingly prevalent with age.
Choroidal fissure closes at what age
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choroidal fissure closure embryology age
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The choroidal fissure (also called the optic fissure or embryonic fissure) closes at 5–7 weeks of gestation (approximately 33–37 days of embryonic development).
Key Details
| Parameter | Detail |
|---|---|
| Structure | Groove on the ventral surface of the optic cup and optic stalk |
| Purpose | Allows entry of the hyaloid artery (which supplies the developing lens and vitreous) |
| Closure timing | ~5–7 weeks gestation (33–37 days) |
| Direction of closure | Begins in the middle of the fissure and proceeds anteriorly and posteriorly simultaneously |
Significance of Non-Closure
Failure of the choroidal fissure to close results in coloboma, which can affect:
- Iris (most clinically visible — keyhole-shaped pupil)
- Ciliary body
- Choroid
- Retina
- Optic nerve
Colobomas are always located inferonasal in position, corresponding to the site of the choroidal fissure.
Mnemonic
"Fissure closes at 5 weeks — failure = coloboma at 5 o'clock/7 o'clock (inferonasal)"
In short: The choroidal fissure closes at 5–7 weeks of gestation. Failure to close causes a coloboma.
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