scholarly journals MYOPIA INDIAN EYES: COMPARING CALCULATED AND MEASURED AXIAL LENGTH IN YOUNG PATIENTS

2020 ◽  
pp. 80-82
Author(s):  
Nirav Mehta ◽  
Shivani Kansara ◽  
Rupam Desai
Keyword(s):  
Axial Length ◽  
Young Patients ◽  
Coefficient Of Determination ◽  
Ocular Biometry ◽  
Corneal Radius ◽  
Eye Examination ◽  
Children And Young Adults ◽  
Schematic Eye ◽  
Preventable Blindness ◽  
Myopia Control

Myopia is the leading cause of preventable blindness in children and young adults in the world. As age increases axial length increasing risks of myopia for causing ocular morbidity including retinal detachment, glaucoma, myopic macular degeneration, and cataracts. In India, much patient eye examination done at primary eye clinic, where to estimate axial length is difficult. Our aim of the study was to assess the reliability of formula by comparing Predicted Axial Length (AL) uses corneal radius and Spherical equivalent (SE) to the measured AL using Ocular Biometry. Method: 96 myopic eyes were included, Comprehensive eye examination with Auto-refractokeratometer using TOPCON-800 and Axial length with Ocular Biometry (IOL Master-500) Calculated Axial length with formula by using AVE-K and SE which is obtained from original Gullstrand simplified Schematic eye: AL= (24.00×AVE-K/7.80–SE×0.40) for both K-reading. Result: Mean Calculated AL(mm) was 24.67 ± .90 and Measured AL (mm) which was 24.28 ± .96mm in 9-25yr age (P<0.001) with Mean difference 0.3±0.4. All groups show statistically significant correlation between Calculate AL and Mean AL (p<0.01, r>0.9). The coefficient of determination (R2) was 82% in 9-25yr age group. Conclusion: Study provides strong agreement between Measured AL and Calculated AL. Alternate method of AL measurement with a calculated formula can be implemented in all primary eye care for predicting Axial length and managing myopic patients for monitoring myopia control.

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.

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 Multifocal Orthokeratology versus Conventional Orthokeratology for Myopia Control: A Paired-Eye Study

2021 ◽  
Vol 10 (3) ◽  
pp. 447
Author(s):  
Martin Loertscher ◽  
Simon Backhouse ◽  
John R. Phillips
Keyword(s):  
Visual Acuity ◽  
Axial Length ◽  
Length Change ◽  
Fellow Eye ◽  
Eye Growth ◽  
Treatment Zone ◽  
Ocular Biometry ◽  
Center Distance ◽  
Myopia Control ◽  
Posterior Cornea

We conducted a prospective, paired-eye, investigator masked study in 30 children with myopia (−1.25 D to −4.00 D; age 10 to 14 years) to test the efficacy of a novel multifocal orthokeratology (MOK) lens compared to conventional orthokeratology (OK) in slowing axial eye growth. The MOK lens molded a center-distance, multifocal surface onto the anterior cornea, with a concentric treatment zone power of +2.50 D. Children wore an MOK lens in one eye and a conventional OK lens in the fellow eye nightly for 18 months. Eye growth was monitored with non-contact ocular biometry. Over 18 months, MOK-treated eyes showed significantly less axial expansion than OK-treated eyes (axial length change: MOK 0.173 mm less than OK; p < 0.01), and inner axial length (posterior cornea to anterior sclera change: MOK 0.156 mm less than OK, p < 0.01). The reduced elongation was constant across different baseline progression rates (range −0.50 D/year to −2.00 D/year). Visual acuity was less in MOK vs. OK-treated eyes (e.g., at six months, MOK: 0.09 ± 0.01 vs. OK: 0.02 ± 0.01 logMAR; p = 0.01). We conclude that MOK lenses significantly reduce eye growth compared to conventional OK lenses over 18 months.

scholarly journals The Influence of Genetics in Myopia Control: A Pilot Study

2021 ◽  
Vol 10 (4) ◽  
pp. 808
Author(s):  
Cristina Alvarez-Peregrina ◽  
Miguel Ángel Sánchez-Tena ◽  
Clara Martinez-Perez ◽  
Catalina Santiago-Dorrego ◽  
Thomas Yvert ◽  
...  
Keyword(s):  
Pilot Study ◽  
Treatment Response ◽  
Axial Length ◽  
Contact Lenses ◽  
Control Method ◽  
Saliva Sample ◽  
Experimental Studies ◽  
Strong Linkage Disequilibrium ◽  
Student’S T ◽  
Myopia Control

Background: Many epidemiological and experimental studies have established that myopia is caused by a complex interaction between common genetic and environmental factors. The objective of this study was to describe and compare the allelic and genotypic frequencies of the rs524952 (GJD2), rs8000973 (ZIC2), rs1881492 (CHRNG), rs1656404 (PRSS56), rs235770 (BMP2), and rs7744813 (KCNQ5) SNPs (single-nucleotide polymorphism) between responder and nonresponder patients who had undergone a two-year treatment with lenses for myopia control. Method: Twenty-eight participants from the MiSight Assessment Study Spain (MASS), who had received treatment for myopia control for two years with MiSight contact lenses, were examined. The criteria for better/worse treatment response was the change in the axial length (< / ≥ 0.22 mm two years after the treatment). The clinical procedure consisted of the extraction of a saliva sample, and the participants also underwent an optometric examination. Genetic data were analyzed using SNPStats software (Catalan Institute of Oncology, Barcelona, Spain), and statistical analysis was performed using SPSS v.25 (SPSS Inc., Chicago, IL, USA). Demographic variables were analyzed using the Student’s t-test. Results: The T allele, the one with the lowest frequency, of the “rs235770” SNP was associated with a better treatment response [AL/CR (axial length/corneal radius): OR = 3.37; CI = 1.079–10.886; SE (spherical equivalent): OR = 1.26; CI: = 0.519–57.169; p = 0.019). By performing haplotype analysis, significant differences were found between the rs235770…rs1881492 and rs235770–rs1656404 polymorphisms. The latter presented a strong linkage disequilibrium with each other (r2 ≥ 0.54). Conclusion: The result of lens therapies for myopia control could vary depending on genetic variants. Studies with a larger sample are needed to confirm the results presented in this pilot study.

scholarly journals Refractive errors, ocular biometry and diabetic retinopathy: a systematic review

2020 ◽  
Author(s):  
Miao He ◽  
Haiying Chen ◽  
Wei Wang
Keyword(s):  
Systematic Review ◽  
Diabetic Retinopathy ◽  
Axial Length ◽  
Protective Factor ◽  
Posterior Vitreous Detachment ◽  
Anterior Chamber Depth ◽  
Protective Role ◽  
Protective Mechanism ◽  
Ocular Biometry ◽  
Systemic Factors

ABSTRACTDiabetic retinopathy (DR) is one of the major causes of visual impairment and blindness worldwide. The onset and progression of DR are influenced by systemic factors such as hyperglycemia and hypertension as well as ocular parameters. A better knowledge of the risk factors for DR is vital to improving the outcome of patients with DR and risk stratification. More recently, there has been increasing focus on the influence of myopia on DR development. Some observational studies have reported myopia being a protective factor for the development of DR, however the findings were inconsistent. In addition, it remains unclear whether it was myopia, axial length (AL), or other refractive factors that play the protective role. The protective mechanism against DR may be related to ocular elongation, posterior vitreous detachment, low perfusion in the retina and the abnormal cytokine profile. This systematic review will summarize the association of DR with refractory status as well as different refractive components including anterior chamber depth, refractory power of the lens, AL, and axial length-to-corneal radius ratio.

scholarly journals Development of Refractive Parameters in 3- to 6-Year-Old Children and Its Application in Myopia Prediction and Intervention Guidance

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Ya Zhang ◽  
Ming Su ◽  
Hua Liu ◽  
Yanxia Song ◽  
Jing Liu ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Clinical Work ◽  
Hebei Province ◽  
Radius Of Curvature ◽  
Spherical Equivalent ◽  
Ocular Biometry ◽  
Refractive Development ◽  
Corneal Radius ◽  
The Mean ◽  
Vision Screener

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.

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.

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