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6 Cards in this Set
- Front
- Back
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Refractive norm in infant (4) |
1. Low to moderate hyperopia (Chinese and European) decrease with age - mean: +2.00D, sd: 2.00D
2. Low to moderate astigmatism, decrease over the first year (Chinese and European)
3. Pattern of astigmatism (prevalence) - WTR astigmatism (Chinese) - WTR=ATR astigmatism (European)
4. Premature infant: higher prevalence of myopia |
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Emmetropization (5) |
1. The eye growths towards emmetropia
2. An active process
3. Describe the refractive development of an individual
4. The development of European eye - hardly appropriate to describe Chinese eye
5. Birth: Gaussian distribution (normal distribution) - variance decreases considerably - age increase: leptokurtic distribution |
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Refractive error change with age Birth to 5 years (3), During school year (5) |
Birth to 5 years: 1. Distribution of refraction (increase lepto-kurtosis: sharp peak) - newborn: large range - age 6-8: -1 - 4 D, sharp peak - mean: +1.00 D
2. HK baby reach emmetropic state much earlier than Italian baby
3. Astigmatism reduce around 3 years - astigmatism in infant is higher in prevalence and in degree (Mohindra 1978)
During school year 1. Refraction of the majority of children change little - increase in kurtosis (peak) of the distribution of Rx - appear as leptokurtic distribution (peak distribution) - mean: +0.50-+1.00D (emmetropic range), sd: 1.00D
2. Low to moderate myopia and progress in some children
3. Skewness in minus direction
4. Little change in mean corneal curvature and anterior segment (anterior chamber depth, lens thickness) with increase age
5. Mean vitreous depth, axial length increase gradually by about 1mm - increase in mean vitreous depth parallel to increase in axial length yearly |
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Prevalence of myopia (3) |
Prevalence of myopia 1. Chinese: 70% by the age of 17 years 2. Myopia start early in Chinese than Caucasian, the average rate of progression is similar (0.50 D) 3. Already myopia: progression rate is 0.9D per year |
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Prevalence of astigmatism and anisometropia (2) |
1. 6-17 years: 50% of children has astigmatism - WTR 2. Anisometropia: spherical/cylindrical difference >1.00 D - spherical anisometropia: 6% girl, 8% boy - cylindrical anisometropia: 2% girl, 2% boy |
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Evidence of emmetropization (4) |
1. Emmetropization continued throughout the school year - reducing hyperopia, reduce mean - reducing refractive range in population, reduced sd 2. Increase in axial length do not result in myopia
3. Anterior segment (corneal curvature, anterior chamber depth, lens thickness) weak correlation Vs Vitreous depth, axial length strong correlation
4. Prevalence of astigmatism and anisometropia decrease with age |
