Axial length/corneal radius of curvature ratio and refractive development evaluation in 3- to 4-year-old children: the Shanghai Pudong Eye Study

Objective. To investigate refractive development and prevalence of myopia in children aged 3-6 years in Hebei Province, China, and to explore the developmental law of refraction, so as to clinically guide the prediction and intervention of myopia. Methods. In May 2019, a total of 6120 people were inspected in 68 kindergartens in 11 cities in Hebei Province. Child refractive refraction was checked under noncycloplegia using a handheld binocular vision screener (SW-800, SUOER, Tianjin, China). Axial length (AL) and corneal radius of curvature (CR) were measured using an ocular biometry (IOLMaster 500, Carl Zeiss, Germany). Myopia was defined as spherical equivalent SE ≤ − 0.75 D . Results. A total of 5506 children aged 3-6 years met the criteria and were included in the statistical analysis. The prevalence of myopia was 3.49% (1.93% at age 3, 2.90% at age 4, 3.78% at age 5, and 3.88% at age 6). Overall, the mean SE was + 0.67 ± 1.05 D ( + 0.81 ± 1.00 D at age 3, + 0.79 ± 1.05 D at age 4, + 0.67 ± 1.08 D at age 5, and + 0.13 ± 1.01 D at age 6); the mean CR was 7.76 ± 0.26 mm ( 7.78 ± 0.26 mm at age3, 7.75 ± 0.25 mm at age 4, 7.77 ± 0.26 mm at age 5, and 7.76 ± 0.25 mm at age 6); the mean AL was 22.31 ± 0.73 mm ( 21.98 ± 0.63 mm at age 3, 22.12 ± 0.69 mm at age 4, 22.34 ± 0.73 mm at age 5, and 22.49 ± 0.73 mm at age 6). Conclusions. Prevalence of myopia increases with age in children aged 3-6 years in Hebei, China. With the increase of age, CR is basically stable, and AL increases gradually. AL/CR, which is closely related to SE, can be used as an indicator to predict myopia and guide clinical work.

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The Role of Axial Length-Corneal Radius of Curvature Ratio in Refractive State Categorization in a Nigerian Population

ISRN Ophthalmology ◽

10.5402/2011/138941 ◽

2011 ◽

Vol 2011 ◽

pp. 1-6 ◽

Cited By ~ 8

Author(s):

Eghosasere Iyamu ◽

Joy Iyamu ◽

Christian Izuchukwu Obiakor

Keyword(s):

Axial Length ◽

Inverse Correlation ◽

Radius Of Curvature ◽

Spherical Equivalent ◽

Refractive State ◽

Spherical Equivalent Refraction ◽

Nigerian Population ◽

Corneal Radius ◽

The Mean

The aim of this study was to investigate the association of axial length (AL)/corneal radius of curvature (CRC) ratio (AL/CRC) with spherical equivalent refractive state (SER) in young adults. A total of seventy () subjects consisting of 31 males and 39 females participated in this study. Subjects were categorized into emmetropia, hyperopia and myopia using the spherical equivalent refraction. The axial length was measured with I-2100 A-Scan ultrasonography/Biometer (CIMA Technology, USA), the corneal radius of curvature with Bausch & Lomb H-135A (Bausch & Lomb Corp., USA), and the refractive state by static retinoscopy and subjective refraction. The mean AL, CRC and AL/CRC ratio of all subjects were 23.74 ± 0.70 mm, 7.84 ± 0.19 mm, and 3.03 ± 0.14, respectively. Myopes had significantly longer AL, steeper CRC and higher AL/CRC ratio than the emmetropes and hyperopes. There was statistically significant inverse correlation between AL and CRC (, ), SER (, ), and between SER and AL/CRC (, ). A significant positive correlation was found between CRC and SER (, ). The categorization of the refractive state of an individual is better done by using the AL/CRC ratio index.

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Proportion and characteristic of emmetropia in schoolchildren aged 6-11y: the Shenzhen elementary school eye study

International Journal of Ophthalmology ◽

10.18240/ijo.2020.12.21 ◽

2020 ◽

Vol 13 (12) ◽

pp. 1983-1989

Author(s):

Xian-Ming Jiang ◽

Xiao Han ◽

Qian Tan ◽

Jun-Shu Wu

Keyword(s):

Elementary School ◽

Axial Length ◽

Primary Schools ◽

Radius Of Curvature ◽

Special Focus ◽

School Students ◽

Normal Value ◽

Biometric Parameters ◽

Corneal Radius ◽

Change Trend

AIM: To investigate the proportion and characteristic of emmetropia in schoolchildren aged 6-11, especially estimate the normal value of ocular biometric parameters of emmetropia. METHODS: A population-based cross-sectional study was conducted on children aged 6-11y in Shenzhen. Totally, 2386 schoolchildren from two primary schools were involved. The axial length (AL) and the corneal radius of curvature (CRC) were measured by partial coherence laser interferometry. Noncycloplegic refraction and refractive astigmatism (RA) was measured using autorefraction. The axial length-to-corneal radius of curvature ratio (AL/CRC), corneal astigmatism (CA) and spherical equivalent refraction (SER) were calculated. RESULTS: The proportion of emmetropia in elementary school students was 41.30%. This percentage decreased gradually from 6 to 11 years of age and decreased rapidly after 9 years of age. The mean and 95%CI of each parameter were provided for boys and girls aged 6 to 11 years of age with emmetropia according to each age group. The change trend of parameters of boys and girls are similar. After 7 years of age, the AL of non-emmetropia started to increase faster than that of emmetropia. The change trend of AL/CRC was the same as that of AL. The other parameters tend to be stable after 7 years of age. CONCLUSION: The age of 7-9 is an important period for the changes of refractive state and ocular biometric parameters of primary school students, and it is a special focus period for children myopia prevention. The normal value and variation of ocular biometric parameters of emmetropia can provide the basis for the clinical judgment of whether or not children’s ocular biometric parameters obtained by single measurement and changes obtained by multiple measurements are abnormal.

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Assessment of Variation in Keratometry with the Axial Length and Refractive Status of the Eye - A Cross Sectional Observational Study in South Asian Population

Journal of Evidence Based Medicine and Healthcare ◽

10.18410/jebmh/2021/51 ◽

2021 ◽

Vol 8 (05) ◽

pp. 267-271

Author(s):

Kajal Seema S ◽

Manasa S ◽

Prasenna M ◽

Kavitha S

Keyword(s):

Observational Study ◽

Axial Length ◽

Tertiary Care ◽

Anterior Chamber Depth ◽

Radius Of Curvature ◽

Corneal Curvature ◽

Cross Sectional ◽

Refractive Status ◽

Iol Power ◽

Corneal Radius

BACKGROUND Refractive status of the eye depends on the balance between multiple factors such as corneal power, lens power, anterior chamber depth and axial length. Compensatory adjustments between the axial length and the keratometry of the cornea play an important role in emmetropisation. Capturing the biometric measurements of the eye is an important part of the preoperative work up of patients to calculate the intraocular lens (IOL) power, hence, the importance of better understanding of the interplay between the biometry parameters. Our aim was to assess the variation of keratometry with the refractive status and axial length of the eye. METHODS This is a cross sectional observational study of 299 eyes that were operated for cataract surgery from July 2018 to December 2018 at a tertiary care centre in South India. Axial length and central corneal curvature were measured and average was taken for analysis. Eyes with axial length ≤ 22 mm were grouped as hyperopic (Group 1), those with axial length between 22.0 mm and 24.0 mm were grouped as normal (Group 2) and eyes with axial length more than 24.0 mm were grouped as myopic (Group 3). The distribution of corneal curvature, AL / K ratio and IOL power across different ranges of axial length was assessed. RESULTS There was a statistically significant flattening of cornea with increase in axial length (P < 0.001). Distribution of axial length to corneal radius of curvature was also found to be statistically significant (P < 0.001) among the three groups. CONCLUSIONS With an increase in axial length there was a statistically significant progressive flattening of cornea. The AL / K ratio can be a better measure of the refractive status of an individual than axial length alone. KEYWORDS Axial Length, Keratometry, Myopia, Hyperopia, Axial Length to Corneal Radius of Curvature Ratio

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Evaluation of the Relationships between Corneal Parameters, Ocular Biometry, and Myopia Magnitude

Sains Malaysiana ◽

10.17576/jsm-2021-5010-20 ◽

2021 ◽

Vol 50 (10) ◽

pp. 3077-3084

Author(s):

Mohd Izzuddin Hairol ◽

Norlaili Arif ◽

Pui Theng Yong ◽

Mariah Asem Shehadeh Saleh Ali ◽

Nik Nor Adlina Nik Idris ◽

...

Keyword(s):

Axial Length ◽

Corneal Thickness ◽

Anterior Chamber Depth ◽

Radius Of Curvature ◽

Corneal Curvature ◽

Ocular Biometry ◽

Corneal Asphericity ◽

Corneal Radius ◽

The Difference ◽

The Relationship

Axial length of the eye correlates with the magnitude of myopia. However, there are conflicting reports on the relationship between certain corneal parameters with myopia magnitude. The objective of this study was to compare ocular biometry and corneal parameters between emmetropic and myopic groups. Participants (n=127) were categorized as emmetropia (spherical equivalent, SE, ±0.50D), low myopia (-0.75D≤SE<-6.00D) and high myopia (SE≥-6.00D). The difference in axial length, anterior chamber depth, and vitreous chamber depth between emmetrope, low myope, and high myope were highly significant (one-way ANOVA, all p<0.001) with significant correlations between SE and all these parameters (simple regressions, all p<0.001). However, central corneal thickness, corneal radius of curvature, and corneal asphericity between these groups, and the correlations between the ocular parameters with SE were not significantly different (all p>0.05). Corneal curvature correlated significantly with axial length (p=0.001) but not with myopia magnitude (p=0.91). Rather than myopia magnitude, axial length appears to be more sensitive to detect changes in corneal curvature in myopes. In conclusion, myopic patients’ axial length should be carefully considered for interventions that involve the cornea, such as orthokeratology and refractive surgery.

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