The Axial Length/Corneal Radius Ratio in Emmetropia and Ametropia: A Review

1997 ◽  
pp. 103-106
Author(s):  
Theodore Grosvenor ◽  
David A. Goss
Keyword(s):  
Axial Length ◽  
Radius Ratio ◽  
Corneal Radius

scholarly journals Axial Length/Corneal Radius Ratio: Association with Refractive State and Role on Myopia Detection Combined with Visual Acuity in Chinese Schoolchildren

PLoS ONE ◽  
2015 ◽  
Vol 10 (2) ◽  
pp. e0111766 ◽  
Author(s):  
Xiangui He ◽  
Haidong Zou ◽  
Lina Lu ◽  
Rong Zhao ◽  
Huijuan Zhao ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Axial Length ◽  
Radius Ratio ◽  
Refractive State ◽  
Corneal Radius

Lens Power, Axial Length-to-Corneal Radius Ratio, and Association with Diabetic Retinopathy in the Adult Population with Type 2 Diabetes

Ophthalmology ◽  
2017 ◽  
Vol 124 (3) ◽  
pp. 326-335 ◽  
Author(s):  
Jiangnan He ◽  
Xian Xu ◽  
Jianfeng Zhu ◽  
Bijun Zhu ◽  
Bo Zhang ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Diabetic Retinopathy ◽  
Axial Length ◽  
Adult Population ◽  
Radius Ratio ◽  
Corneal Radius ◽  
Lens Power

scholarly journals Impact of the anterior-posterior corneal radius ratio on intraocular lens power calculation errors

2018 ◽  
Vol Volume 12 ◽  
pp. 1549-1558 ◽  
Author(s):  
Asato Hasegawa ◽  
Takashi Kojima ◽  
Mana Yamamoto ◽  
Yukihito Kato ◽  
Akeno Tamaoki ◽  
...  
Keyword(s):  
Intraocular Lens ◽  
Radius Ratio ◽  
Power Calculation ◽  
Intraocular Lens Power Calculation ◽  
Intraocular Lens Power ◽  
Corneal Radius ◽  
Lens Power ◽  
Lens Power Calculation ◽  
Anterior Posterior

Evaluation of the B/F Ratio Distribution of Cataract Patients Without Corneal Abnormalities and Its Effect on Ocular Parameters

2021 ◽  
Vol 44 (4) ◽  
pp. E46-54
Author(s):  
Michael Deng ◽  
Lina Lan ◽  
Tianhui Chen ◽  
Min Zhang ◽  
Jiahui Chen ◽  
...  
Keyword(s):  
Axial Length ◽  
Central Corneal Thickness ◽  
Spherical Aberration ◽  
Linear Regression Analysis ◽  
Corneal Thickness ◽  
Curvature Radius ◽  
Multivariate Linear Regression Analysis ◽  
Corneal Surface ◽  
Ratio Distribution ◽  
Corneal Radius

Purpose: To evaluate the distribution of the posterior-anterior corneal radius ratio (B/F ratio; posterior corneal radius/anterior corneal radius) in patients without corneal abnormalities, and to investigate which parameters affect this ratio. Methods: Five thousand eyes from 5,000 patients who underwent cataract surgery were recruited to this study. We explored the linear relationship between B/F ratio and 13 variables using Principal Component-Multivariate Linear Regression Analysis. Results: The B/F ratio was negatively correlated with the difference between simulated keratometry (SimK) and true net power (TNP), central corneal thickness, spherical aberration (SA), and posterior corneal astigmatism and positively correlated with posterior corneal radius, corneal posterior surface, axial length (AL) and anterior corneal radius. Several variables (central corneal thickness, difference between SimK and TNP and asphericity coefficient (Q-value) of the posterior corneal surface) had the highest loading on the final score. B/F ratio reflects the refractive state and anatomical structure of the cornea: thus, higher B/F ratios were associated with larger posterior corneal surface curvature radius, longer axial length, thinner central corneal thickness, lower high order aberrations of the cornea and SA, and the numerical difference between simK and TNP gradually reduced. In clinical practice, for patients with lower B/F ratio, special care should be taken in the choice of system used for intraocular lens (IOL) measurements.

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

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
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.

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

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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