spherical equivalent
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2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Chenghai Weng ◽  
Fei Xia ◽  
Dang Xu ◽  
Xingtao Zhou ◽  
Liangcheng Wu

Abstract Background Myopia is a global public health issue. Controlling myopia progression is a primary focus of myopia studies today. Peripheral retinal myopic defocus is considered the mechanism for reduced myopia progression in orthokeratology studies. The topographic change in the front corneal surface after laser refractive surgery and orthokeratology procedures may appear similar. The purpose of this study was to explore the role of myopic laser ablation on axial length (AL) growth. Methods Myopic patients who underwent monocular excimer laser refractive surgery first in one eye and then in another eye several years later because of myopia occurrence or myopia progression were recruited. The axial length elongation and refraction (spherical equivalent) between the two eyes were observed and compared. Results A total of 8 myopic patients were enrolled in the study. The AL increased from 24.52 ± 0.96 mm to 24.68 ± 1.03 mm but without significance (T = 1.49, P > 0.05) in the ablated eyes. The AL increased significantly from 23.73 ± 0.91 mm to 24.26 ± 0.95 mm in the nonablated eyes (T = 6.76, P < 0.001). The AL elongation of the ablated eyes with 0.16 ± 0.30 mm growth was significantly lower than that of the nonablated eyes with 0.53 ± 0.32 mm growth (T = 8.98, P < 0.001). The spherical equivalent (SE) increased significantly in the ablated eyes (− 0.59 ± 0.21 (D), T = 6.36, P < 0.001) and in the nonablated eyes (− 0.97 ± 0.55 (D), T = 4.91, P < 0.01), and the difference between the two eyes was significant (T = 3.05, P < 0.05). Conclusions The inhibitory effect of myopic laser ablation on AL elongation reported in the limited case studies argues for animal research on its efficacy as a new intervention for myopia progression.


2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Ammar M Khan ◽  
Derek M. Waldner ◽  
Micah Luong ◽  
Emi Sanders ◽  
Andrew C. S. Crichton ◽  
...  

Abstract Background Accumulating evidence suggests that refractive stabilization occurs rapidly following small incision cataract surgery. Nonetheless, many guidelines still suggest waiting four to 6 weeks before prescribing corrective lenses. This study was undertaken to supplement the existing literature regarding refractive stabilization, and evaluate multiple contributing factors that could dissuade clinicians from confidently correcting refractive error in the early post-operative course following routine cataract surgeries. Methods Adult patients undergoing phacoemulsification cataract surgery with uncomplicated surgeries and post-surgical courses at the Calgary Ophthalmology Centre (Calgary, Alberta, Canada) were included in this prospective observational case series. Exclusion criteria included known corneal dystrophies, infectious keratitis, complicated surgery or toric/multifocal IOLs. Data was collected at weekly intervals for a total of 6 weeks. Collected data included autorefraction, visual acuity, corneal pachymetry, and effective lens position. Results One hundred six eyes of 104 patients were included in this study. Post-operative sphere, cylinder and spherical equivalent were not significantly different at any post-operative week compared with week six, and 80–86% of patients were within 0.5D of last follow-up spherical equivalent at any week. The secondary outcomes of central corneal thickness, effective lens position and visual acuity did, however, exhibit significant differences between early post-operative weeks and last follow-up values. Conclusions These data suggest that refractive error can be effectively measured and corrected as early as one-week post-operatively in the majority of patients, though other measures of post-operative stability including central corneal thickness, effective lens position and visual acuity can require up to 4 weeks to stabilize. Thus a conservative and pragmatic approach may be to wait until 4 weeks post-operatively prior to obtaining refractive correction following uncomplicated phacoemulsification cataract surgery.


2021 ◽  
pp. bjophthalmol-2021-319568
Author(s):  
Alexandre Ducloux ◽  
Simon Marillet ◽  
Pierre Ingrand ◽  
Mark A Bullimore ◽  
Rupert R A Bourne ◽  
...  

BackgroundThe prevalence of myopia is increasing worldwide. The purpose of this study was to evaluate the progression of myopia in teenagers and adults in France.MethodsThis nationwide prospective study followed 630 487 myopic adults and teenagers (mean age 43.4 years±18.2, 59.8% of women) between January 2013 and January 2019. Myopia and high myopia were defined as a spherical equivalent less than or equal to –0.50 and –6.00 diopters (D), respectively. Demographic data were collected at first visit and refractive characteristics were collected at each visit. Analysis of short-term progression (first 12 to 26 months postbaseline) was modelled using analysis of variance (ANOVA). Progression of myopia was stratified according to age, gender and spherical equivalent at first visit.ResultsHigher proportions of progressors were observed in the youngest age groups: 14–15 (18.2 %) and 16–17 years old (13.9 %). In multivariate analysis, after adjustment for over age, spherical equivalent and gender, the mean short-term progression decreased from –0.36 D in the 14–15 years age group to –0.13 D in the 28–29 years age group. Young age and higher myopia at baseline together were strongly associated with the risk of developing high myopia, the 5-year cumulative risk being 76% for youngest teenager with higher myopia status at baseline.ConclusionIn this large cohort of myopic teenagers and adults, myopia progression was reported in 18.2% and 13.9% of the 14–15 and 16–17 age groups, respectively. The risk to develop high myopia was higher for younger individuals with higher myopia at baseline examination.


2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Ya Zhang ◽  
Ming Su ◽  
Hua Liu ◽  
Yanxia Song ◽  
Jing Liu ◽  
...  

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.


2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Amr A. Gab-Alla

Purpose. To evaluate the outcome of the reversal of myopia correction in patients intolerant to LASIK. Methods. This study is a retrospective and case series of patients who decided to reverse their previous myopic LASIK correction between July 2012 and July 2020. It was conducted at a private refractive surgery centre, Ismailia, Egypt. The patients were followed up after reversal treatment for one year. Primary LASIK and reversal treatment were performed by a 500 kHz Amaris excimer laser platform. The main outcomes included refractive predictability, stability, efficacy, and safety and any reported complications. Results. This study included 48 eyes of 24 patients (6 male and 18 female patients). The average duration between the primary LASIK surgery and reversal treatment was 3.20 ± 0.30 months (range 3 to 4 months). Reversal treatment was bilateral in all patients. The mean age of the patients was 38 ± 1.9 years (range 37 to 45 yrs). After reversal, the mean postreversal cycloplegic refraction spherical equivalent was −1.82 ± 0.34 D (range −1.50 to −3.00 D). The mean ablation depth was 34.10 ± 7.36 μm (range 20 to 46 μm), and the mean of the central corneal thickness 12 months after reversal treatment was 510.2 ± 14.4 μm (range 515 to 487 μm). The mean keratometric reading was 42.6 ± 1.6 (range 42.5 to 44.8). The mean of CDVA was 0.2 ± 0.03 log MAR (range −0.10 to 0.4 log MAR). The mean optical zone of reversal treatment was 6.1 ± 0.3 mm (range 5.9 to 6.2 mm). UDVA was 0.4 log MAR in 87.5% of the patients, 0.5 log MAR in 8.3% of the patients, and 0.6 log MAR in 4.2% of the patients. CDVA remained unchanged in 83.3% of patients; 2.1% of the patients gained one line of CDVA (Snellen); 8.3% of the patients lost one line of CDVA; 6.3% of the patients lost two lines of CDVA. No cases of corneal ectasia were recorded. The only postoperative complications were flap microfolds in 3 eyes (6.25%). Conclusion. In conclusion, this study demonstrates that reversal of myopic LASIK treatment is a safe, stable, and effective option for intolerant patients.


Diagnostics ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2357
Author(s):  
Shu-Min Tang ◽  
Xiu-Juan Zhang ◽  
Marco Yu ◽  
Yu-Meng Wang ◽  
Carol Y. Cheung ◽  
...  

Associations between corneal biomechanics, axial elongation and myopia are important but previous results are conflicting. Our population-based study aimed to investigate factors associated with corneal biomechanics, and their relationships with myopia in children and adults. Data from 3643 children and 1994 parents showed that children had smaller deformation amplitudes (DA) than parents (p < 0.001). A larger DA was significantly associated with elongated axial length (AL; children: ß = 0.011; adults: ß = 0.0013), higher corneal curvature (children: ß = 0.0086; adults: ß = 0.0096), older age (children: ß = 0.010; adults: ß = 0.0013), and lower intraocular pressure (IOP; children: ß = −0.029; adults: ß = −0.031) in both cohorts. The coefficient of age for DA in children was larger than in adults (p < 0.001), indicating that the DA change with age in children is faster than in adults. DA was significantly associated with spherical equivalent (p < 0.001) resulting from its correlation with AL and corneal curvature. In conclusion, the cornea is more deformable in adults than in children, whereas corneal deformation amplitude increases faster with age in children than that in adults, along with AL elongation. Longer AL, steeper corneal curvature, older age and smaller IOP correspond to a more deformable cornea. The association between corneal deformation amplitude and refraction was mediated via AL and corneal curvature.


2021 ◽  
Author(s):  
Yan Xu ◽  
Jun Chen ◽  
Chun Tang ◽  
Kaidi Xiang ◽  
Lipu Cui ◽  
...  

Abstract Purpose: This study aimed to observe the changes in spherical equivalent and ocular axial length 6 months after withdrawal of 1% atropine eye gel.Methods: Due to COVID-19, the follow-up of patients in our optometric clinic who were undergoing myopia control treatment with a dropwise 1% atropine “5+3” regimen was interrupted. No return visit was made after the 3 months of at-home treatment, and follow-ups resumed 6 months after treatment withdrawal. The contralateral eye was not treated over the 9-month period. A total of 16 patients aged 11.5 years (average) were enrolled from November 2019 to March 2021 during the COVID-19 pandemic. The treated eyes formed a treatment group (16 eyes) and the contralateral eyes formed a control group (16 eyes). The changes in spherical equivalent, ocular axial length, and intraocular pressure (IOP) were compared between groups. Results: After 9 months, the changes in spherical equivalent were significantly less in the treatment group (0.00 ± 0.20 [D]) compared to the control group (-0.67 ± 0.25 [D]) (P<0.05). The ocular axial length changes were significantly less in the treatment group (0.00 ± 0.06 mm) compared to the control group (0.25 ± 0.11 mm) (P<0.05). There was no significant difference between the two groups for changes in IOP. Conclusions: Despite treatment withdrawal after 3 months, treatment with 1% atropine eye gel successfully controlled myopia progression in the 6 months after withdrawal, as evidence by no rebound increase in myopic spherical equivalent after the withdrawal.


2021 ◽  
Author(s):  
Gozde Orman ◽  
Ozlem Aydinoglu-Candan ◽  
Gulten Sungur

Abstract Purpose: The aim of this study was to investigate the prevalance of congenital optic disc (OD) anomalies in Turkey. Methods: The 11149 eyes of 5583 patients were screened for OD anomalies. All patients were underwent a complete ophthalmic examination including best corrected visual acuity, refraction, spherical equivalent, slit lamp biomicroscopy, intraocular pressure measurements, dilated stereoscopic fundus examination. Data analyses were performed by using SPSS for Windows, version 22.0 (SPSS Inc., Chicago, IL, United States).Results: 11149 eyes of 5583 participants were screened. Of the 5583 participants who underwent OD examination, 186 (3,3%) were found to be abnormal. 266 of 11149 (2,38%) eyes were found OD anomalies. 98 (52,7%) were female, 88 (47,3%) were male and the mean of age was 44,05±15,73 years. The prevalence of all congenital OD anomalies was found 3,3%. The tilted disc was the most common anomaly and was found at least one eye in 46 patients (75 eyes) and 0.82% of all screened patients. Peripapillary myelinated nerve fibres was the second common anomaly and was found at least one eye in 29 subjects (35 eyes) and 0,51% of all screened subjects. Peripapillary atrophy was the third common anormality, and was found in at least one eye in 24 patients (37 eyes) and 0,42% of all screened subjects.Conclusion: To our knowledge, this is the first study that the prevalences of all congenital optic disc anomalies from Turkey. The prevalence of congenital optic disc anomalies is higher than in other countries.


2021 ◽  
Author(s):  
Victor Rodriguez -Lopez ◽  
Alfonso Hernandez-Poyatos ◽  
Carlos Dorronsoro

AbstractWe present the Direct Subjective Refraction (DSR), a new subjective refraction method, and validate it vs the Traditional Subjective Refraction (TSR) and an unsupervised version of it (UTSR). We project an optotunable lens onto the eye to create Temporal Defocus Waves produces flicker and chromatic distortions, minimum when the mean optical power of the wave matches the spherical equivalent of the eye. 25 subjects performed the DSR visual and UTSR tasks without supervision. DSR is more repeatable than TSR and UTSR (standard deviations ±0.17D, ±0.28, and ±0.47D). The time per repetition of DSR is only 39s (almost 6 min for TSR). Cyclopegia severely affects UTSR, but not DSR, confirming that the DSR task de-activates the accommodative system. DSR is a new method to obtain the spherical equivalent that does not requires supervision and overpasses existing subjective methods in terms of accuracy, precision, and measurement time.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Müjdat Karabulut ◽  
Sinem Karabulut ◽  
Aylin Karalezli

Abstract Background To compare the refractive results of hand-held and table-mounted autorefractors. Methods We designed this study as an observational, cross-sectional study. We compared the mean spheric and cylinder power, spherical equivalent, Jackson cross-cylinder values, determined the limits of agreement (LoA), and evaluated the reliability of two autorefractors. Results We evaluated 256 eyes of 256 pediatric patients (mean age, 9.12 ± 2.26 years; range, 5–16 years). 49% of the patients were female, and 51% were male. The Nidek HandyRef-K autorefractor measured relatively more astigmatism (P < 0.001) and less hyperopia (P = 0.024). The mean differences and 95% LoA were 0.06 D ± 0.47 D (− 0.82 D to 0.98 D) in spherical power, 0.08 D ± 0.28 D (− 0.47 D to 0.64 D) in cylindrical power, 0.11 D ± 0.47 D (− 0.81 D to 1.01 D) in spherical equivalent, 0.02 D ± 0.36 D (− 0.73 D to 0.69 D) in Jackson cross-cylinder power at 0°, 0.005 D ± 0.54 D (− 1.07 D to 1.06 D) in Jackson cross-cylinder power at 45°. We found the difference within 0.50 D in 244 (95%) eyes for spherical power, in 245 (96%) eyes for cylindrical power, 228 (89%) eyes for spherical equivalent, 224 (87%) eyes for Jackson cross-cylinder power at 0°, 213 (83%) eyes for Jackson cross-cylinder power at 45°. When comparing devices, there were strong correlations for spherical power (Spearman’s rho = 0.99, P < 0.001), cylindrical power (Spearman’s rho = 0.88, P < 0.001), and spherical equivalent (Spearman’s rho = 0.98, P < 0.001). Conclusion Two autorefractors showed clinically applicable agreement limits; excellent reliability for spherical power and spherical equivalent and good reliability for cylindrical power; high positive percent agreement for spherical and cylindrical power, spherical equivalent, Jackson cross-cylinder power at 0°and 45°. These results showed that both devices might be used interchangeably for screening of refractive error in children.


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