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

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.

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

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

scholarly journals Effect of Cycloplegia on Keratometric and Biometric Parameters in Keratoconus

2016 ◽  
Vol 2016 ◽  
pp. 1-6
Author(s):  
Nihat Polat ◽  
Abuzer Gunduz
Keyword(s):  
Axial Length ◽  
Healthy Subjects ◽  
Anterior Chamber Depth ◽  
Corneal Curvature ◽  
Corneal Surface ◽  
Biometric Parameters ◽  
Before And After ◽  
The Difference ◽  
Group 2 ◽  
Group 1

Purpose.To obtain information about effect of cycloplegia on keratometry and biometry in keratoconus.Methods.48 keratoconus (Group 1) and 52 healthy subjects (Group 2) were included in the study. We measured the flat meridian of the anterior corneal surface (K1), steep meridian of the anterior corneal surface (K2), lens thickness (LT), anterior chamber depth (ACD), and axial length (AL) using the Lenstar LS 900 before and after cycloplegia.Results.The median K1 in Group 1 was 45.64 D before and 45.42 D after cycloplegia, and the difference was statistically significant (P<0.05). The median K2 in Group 1 was 50.96 D before and 50.17 D after cycloplegia, and the difference was significant (P<0.05). The median K1 and K2 in Group 2 were 42.84 and 44.49 D, respectively, before cycloplegia, and 42.84 and 44.56 D after cycloplegia, and the differences were not statistically significant (allP>0.05). There were significant differences in SE, LT, ACD, and RLP between before and after cycloplegia in either Group 1 (allP<0.05) or Group 2 (allP<0.05). There were not statistically significant differences in AL between before cycloplegia and after cycloplegia in either Group 1 (P=0.533) or group 2 (P=0.529).Conclusions.Flattened corneal curvature and increase in ACD following cycloplegia in keratoconus patients were detected.

scholarly journals Ocular biometry and power of intra ocular lens among cataract patients in rural Eastern Ethiopia

2020 ◽  
Author(s):  
MANDEFRO SINTAYEHU KASSA ◽  
GIRUM W GESSESSE
Keyword(s):  
Anterior Chamber ◽  
Axial Length ◽  
Anterior Chamber Depth ◽  
Multiple Linear Regression Model ◽  
P Value ◽  
Corneal Curvature ◽  
Ocular Lens ◽  
Eastern Ethiopia ◽  
Ocular Biometry ◽  
The Mean

Abstract Background : The main objective of the study was to report on the main parameters of ocular biometry and Intra ocular lens power of patients attending a cataract surgical program in Eastern Ethiopia. Methods : The study was a cross sectional study on 765 eyes which were legible for cataract surgery during a mass eye camp conducted from April 04 to April 10, 2018 at Bisidimo Hospital,Eastern Ethiopia.Ocular biometric parameters such as axial length (AL), anterior chamber depth (ACD), mean corneal curvature (MCC) were measured using automated keratorefractometer(Retinomax) and Sonomed A - Scan. Analysis of variance and multivariate analysis were done to determine association of ocular biometry components with socio demography of the study subjects. Results : A total of 765 eyes were enrolled in this study. The mean corneal curvature and the mean anterior chamber depth were found to be 7.61 mm and 2.88mm respectively. The mean axial length was estimated to be 22.98 mm. The mean refractive power of Intra ocular lenses was calculated to be 19.34D. The mean axial length in females was shorter than that of males by 0.24 and this was statistically significant ( P - value = 0.01). Under multiple linear regression model gender had a statistically significant impact on the axial length. The mean Anterior chamber depth in males was also larger than that of females by nearly 0.1 and this was statistically significant (P - value = 0.001). Under multiple linear regression model both age and gender had a statistically significant impact on the anterior chamber depth. There was no a statistically significant difference on the mean Intra ocular lens power required for male and female patients.Conclusion : This study is the first of its kind to provide a larger population based normative data on the most important parameters of ocular biometry in Ethiopia.The female sex was a strong predictor of small axial length and shallow anterior chamber. Increasing age had no effect on the axial length but was found to be a stronger predictor of shallow anterior chamber. Key words : Axial length, Anterior chamber depth, Corneal curvature, Intra ocular lens.

scholarly journals Effect of Stature on Refraction and Ocular Biometry in Chinese Young Adults: The Anyang University Students Eye Study

2019 ◽  
Author(s):  
Ningli Wang ◽  
Shi-Fei Wei ◽  
Yun-Yun Sun ◽  
Shi-Ming Li ◽  
Jian-Ping Hu ◽  
...  
Keyword(s):  
Young Adults ◽  
University Students ◽  
Axial Length ◽  
Negative Refraction ◽  
Anterior Chamber Depth ◽  
Biometric Parameters ◽  
Ocular Biometry ◽  
Corneal Radius ◽  
Chinese Young Adults ◽  
Near Work

Abstract Background There are few studies reporting the association between stature and ocular biometry as well as cycloplegic refraction in young adults. Our study determined the relationship between stature and ocular biometry as well as cycloplegic refraction in Chinese young adults. Methods This was a school-based study including university students in Anyang, Henan Province, China. Cycloplegic refraction and corneal curvature (CR) were measured using an autorefractor. Ocular biometric parameters, including axial length (AL), anterior chamber depth (ACD), and lens thickness (LT), were measured using a Lenstar LS900. Height and weight were acquired from an annual standardized physical examination, and body mass index (BMI) was calculated from these measurements. Results A total of 5657 (71.0%) subjects were available for analysis. After adjusting for age, gender, parental myopia, time outdoors, near work and weight, a 1 cm taller person could be expected to have more negative refraction as -0.023D, a 0.032 mm increase in AL, a 0.003 mm increase in ACD, a 0.008 mm increase in CR, and a 0.001 increase in axial length-corneal radius (AL/CR) ratio. With regard to weight, a 1 kg heavier person was more likely to have less negative refraction as 0.011 D, deeper ACD by 0.001mm and flatter cornea by 0.002mm. A similar pattern of significant associations was also found in BMI. Conclusions Compared to those of less height, young adults of greater height tended to have longer eyes, deeper anterior chambers, flatter corneas, higher AL/CR ratio, and more negative refraction after controlling for potential confounders. In contrast, heavier and higher BMI persons were more hyperopic. The differences in stature may partially explain the variation in refraction and ocular biometric parameters.

scholarly journals Presbyopia and its anatomical and physiological variants

1970 ◽  
Vol 3 (2) ◽  
pp. 155-158
Author(s):  
M Gupta ◽  
RR Sukul ◽  
Y Gupta ◽  
M Dey ◽  
A Phougat ◽  
...  
Keyword(s):  
Anterior Chamber ◽  
Axial Length ◽  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Anterior Chamber Depth ◽  
Physiological Parameters ◽  
Corneal Curvature ◽  
Lens Thickness ◽  
Significant Difference ◽  
The Mean

Aim: To study the various ocular anatomical and physiological parameters in presbyopia. Materials and methods: We studied the various ocular anatomical and physiological parameters like corneal curvature (keratometry readings: K1 and K2), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT) and axial length (AL) in 100 presbyopic patients between 35 - 55 years of age. The patients were divided into two age groups: I (35 – 44 years) and II (45-55 yrs). ACD, AL and LT were measured using an Ascan. CCT was measured with ultrasonic pachymetry. Results: The CCT decreased (BE), LT increased and ACD decreased (RE) significantly with increasing age (p < 0.05). There was no significant difference in males and females. Nearly 3/4th of the total increase in lens thickness was responsible for the decrease in the anterior chamber depth and the rest, 1/4th , goes posteriorly. Corneal curvature and AL showed no significant change with age. Conclusions: The mean of CCT decreased significantly with advancing age. As age increased, the mean value of lens thickness increased and anterior chamber depth decreased. Nearly 3/ 4th of total increase in LT was anteriorly, decreasing the ACD. Corneal curvature and AL has no relation with age. Key words: Presbyopia, central corneal thickness, anterior chamber depth, lens thickness, axial length DOI: http://dx.doi.org/10.3126/nepjoph.v3i2.5269 Nepal J Ophthalmol 2011; 3(2): 155-158

scholarly journals Comparing biometry in normal eyes of children with unilateral cataract/corneal disease to age-matched controls

2016 ◽  
Vol 7 (2) ◽  
pp. 108-116
Author(s):  
Adem Gul ◽  
Adnan Cinal ◽  
Cagatay Caglar ◽  
Tekin Yasar ◽  
Adil Kilic
Keyword(s):  
Anterior Chamber ◽  
Axial Length ◽  
Central Corneal Thickness ◽  
Pediatric Patients ◽  
Corneal Thickness ◽  
Anterior Chamber Depth ◽  
Control Group ◽  
Study Group ◽  
Lens Thickness ◽  
The Difference

Objective: To compare ocular biometry and central corneal thickness of unaffected healthy eyes of pediatric patients with monocular cataracts/corneal opacities and age- matched controls.Materials and methods: We studied 329 eyes of 329 children who were between 1 and 12 years old. The study group (n: 164) consisted of healthy fellow eyes of children operated for unilateral congenital/traumatic cataract and corneal laceration. Axial length, anterior chamber depth, lens thickness, vitreous chamber depth, and central corneal thickness were measured by ultrasound biometry/ pachymetry. Results: Axial length was 22.16 mm in the study group and 21.99 mm in the control group. Anterior chamber depth, lens thickness, and vitreous chamber depth results were 3.35; 3.64 and 15.20 in the treatment group and 3.20; 3.63, and 15.15 mm in the control group, respectively. The axial length and all the components, i.e. anterior chamber depth, lens thickness, and vitreous chamber depth are higher in the unaffected healthy eyes of the pediatric patients than that of the control group but only the difference in the anterior chamber depth was statistically significant. The central corneal thickness was 548 microns and 559 microns in the study and the control groups, respectively, and the difference was found to be significant. Conclusion: Greater anterior chamber depth was chiefly responsible for the overall increase in the axial length in the study group. The central corneal thickness was significantly thinner in the study group than that of the control group. 

scholarly journals Multi-Factor Analysis of the Influence of Orthokeratology on Controlling Myopia in Adolescents

2020 ◽  
Author(s):  
Shijin Wen ◽  
Siqi Ma ◽  
Chuchu Xiao ◽  
Shengfa Hu ◽  
Xufang Ran ◽  
...  
Keyword(s):  
Axial Length ◽  
Corneal Thickness ◽  
Age Groups ◽  
Pairwise Comparison ◽  
Length Change ◽  
Corneal Curvature ◽  
The Third ◽  
The Mean ◽  
The Difference ◽  
Clinical Records

Abstract Background To investigate which baseline factors are predictive for axial length growth over an average period of 1 years in a group of adolescents wearing orthokeratology (OK) contact lenses.Methods In this retrospective study, the clinical records of 189 new OK wearers (378 eyes) between 2014 and 2018 at Xiangya Hospital of Central South University were reviewed. The primary outcome measure was axial length change from baseline to the time of 1 year. Independent variables included baseline measures of age at initiation of OK wear, refractive error (spherical equivalent), corneal thickness, corneal curvature. (1) Age group, 8 ~ 10 years old is the first group, 10 ~ 13 years old is the second group, ≥13 years old is the third group; (2) Myopia degree group, ≥-3.00D is the first group, -3.00 ~ -6.00D is the second group, <-6.00D is the third group; (3) corneal thickness group, ≤550μm is the first group,> 550μm is the second group; (4) corneal curvature group, ≤42.0D is The first group, 42.0 ~ 44.0D is the second group,> 44.0D is the third group.Results ANOVA was used to analyze the difference between the baseline axial length of each group and the axial length for 1 year after continuous wearing of orthokeratology: (1)The mean axial difference between different age groups are 0.251mm, 0.033mm,and 0.112mm, and the difference of the three groups is not statistically significant (F=2.279，P=0.104). By pairwise comparison, only the difference between the first group and the third group is statistically significant (P=0.041); (2) The mean axial difference between different myopia degree groups are 0.173mm, 0.109mm and -0.008mm, and the difference of the three groups is statistically significant (F=8.340，P=0.000 ). By pairwise comparison, the difference between the first group and the second group is statistically significant (P=0.000) and the difference between the first group and the third group is statistically significant(P=0.016); (3) The mean axial difference between different corneal thickness groups and corneal curvature groups is not statistically significant.Conclusions OKs are effective in controlling axial length elongation and myopic progression in adolescents, particularly in younger children with higher myopia.

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