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The effect of part-time wear of 2-zone concentric bifocal spectacle lenses on refractive error development & eye growth in young chicks
摘要： The purpose of this study is to characterize in young chicks the myopia control effects of part-time wear of two-zone concentric bifocal lenses. Nine-day-old chicks (n = 115) were first made myopic with monocular ?10 Diopter (D) single vision (SV) lenses worn for 3 days. Over the 6 days following myopia induction, either 1) two-zone bifocal lenses (?10 D center/?5 D periphery, BFDC) were worn for 12 (full-time), 10, 8, or 6 h, with ?10 D SV lenses worn for the remainder of the day, or 2) BFDC or BFNC (?5 D center/?10 D periphery) lenses were worn every other day (EOD). Control birds wore ?10 D SV lenses every day. Refractive error (RE) and axial ocular dimensions were monitored every three days with retinoscopy and high frequency A-scan ultrasonography respectively. Mean interocular RE and axial length differences after 3 days of myopia induction ( ± SEM) were ?9.6 ± 0.19 D and 0.26 ± 0.01 mm across the groups. At the end of the following 6-day treatment period, equivalent values were: ?10.66 ± 0.28 D, 0.42 ± 0.02 mm (SV-control); 1) ?4.61 ± 0.29 D, 0.26 ± 0.02 mm (BFDC, 12 h); ?4.82 ± 0.23 D, 0.28 ± 0.02 mm (BFDC, 10 h); ?5.21 ± 0.27 D, 0.24 ± 0.02 mm (BFDC, 8 h); ?6.34 ± 0.34 D, 0.25 ± 0.03 mm (BFDC, 6 h); 2) ?8.29 ± 0.29 D, 0.32 ± 0.03 mm (BFDC, EOD), and ?8.83 ± 0.36 D, 0.33 ± 0.03 mm (BFNC, EOD). Overall, full-time BFDC and part-time BFDC and BFNC lens groups exhibited similar changes and were less myopic than the SV group. The results suggest that bifocal lenses may have myopia control effects even when worn part-time, interleaved with standard (SV) myopic corrections, especially if worn for at least 6 h per day.
关键词： Myopia,Axial length,Chicks,Bifocal lenses,Refractive error
更新于2025-09-23 15:23:52
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Comparison of immersion ultrasound and low coherence reflectometry for ocular biometry in cataract patients
摘要： ● Aim: To compare the results of axial length (AL) biometry in cataract eyes by three methods: immersion B-ultrasound (iB) biometry, immersion A-ultrasound (iA) biometry and optical low coherence reflectometry. ● Methods: In this prospective observational study of eyes with cataract AL measurements were performed using immersion ultrasound and optical low coherence reflectometry device. The results were evaluated using Bland-Altman analyses. The differences between both methods were assessed using the paired t-test, and its correlation was evaluated by Pearson coefficient. ● Results: Eighty eyes of 80 patients (39 men and 41 women) for cataract surgery were included in the study. The values of AL could be got from all 80 eyes by iB and iA, the difference of AL measurements between iA and iB was of no statistical significance (P=0.97); the mean difference in AL measurements was -0.031 mm (P=0.26; 95%CI, -0.09 to 0.02); linear regression showed an excellent correlation (r=0.98, P<0.0001). Forty-five of eighty eyes with results of AL measurements, which can be obtained by three methods; the difference of AL measurements was of no statistical significance (iA vs iB, P=0.18; iA vs Lenstar, P=0.51; iB vs Lenstar, P=0.07); linear regression showed an excellent correlation (iA vs iB, r=0.99; iA vs Lenstar, r=0.96; iB vs Lenstar, r=0.96); Bland-Altman analysis also showed good agreement between the two methods [iA vs iB, 95% limits of agreement (LoA), -0.36 to 0.28 mm; iA vs Lenstar, 95% LoA, -0.65 to 0.69 mm; iB vs Lenstar, 95% LoA, -0.55 to 0.68 mm]. ● Conclusion: Measurements with the optical low coherence reflectometry correlated well with iB and iA.
关键词： ultrasonography,axial length,immersion,biometry
更新于2025-09-23 15:23:52
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Portable Autorefractors for Detecting Axial Length Changes in Space
摘要： We evaluated the reproducibility of two portable, self-administered autorefractors (Netra and SVOne Pro) to assess the time course of visual changes on the ISS. METHODS: We measured cycloplegic refractive error at 5 visits at least a week apart in 13 subjects (6 women, 7 men, 30 6 9 yr) using both devices seated and also prone with lower body positive pressure (LBPP) applied. Axial length was measured with an optical biometer. Subjects completed a questionnaire on device preferences. RESULTS: The SVOne seated intrasession reproducibility coefficient (RPC) was 0.37 diopters (D), while the Netra's was 0.41 D. Intersession seated results were: RPC 5 0.67 D for the SVOne and RPC 5 0.54 D for the Netra. The average seated to prone LBPP differences were significantly different from zero for both the SVOne and Netra. The SVOne was preferred in four out of five categories on the questionnaire and took half the time to complete a measurement set compared to the Netra. DISCUSSION: Users preferred the SVOne and it took less time. An SVOne refraction change of 0.67 D from baseline would happen by chance less than 5% of the time. If multiple separate measurements were taken, the detection limit could be reduced (e.g., three repeated measurements could reduce it to 0.38 D). Since astronauts with visual changes show spherical equivalent changes of 0.5 to 1.0 D, in-flight autorefractors could help determine the time course of refractive changes in space from which changes in axial length could be inferred.
关键词： spaceflight-associated neuro-ocular syndrome,portable autorefractor,axial length,refractive error
更新于2025-09-23 15:23:52
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Intrapersonal comparison of initial axial length, keratometric readings, and intraocular lens power over a 6-month interval using an IOLMaster device
摘要： Purpose: In order to improve current biometry practice, we investigated changes in axial length (AL), keratometry (K), and intraocular lens (IOL) power measured by the IOLMaster in adults within a 6-month period at the outpatient eye clinic, King Chulalongkorn Memorial Hospital, Bangkok, Thailand. Patients and methods: This was a nonrandomized prospective cohort study. The AL, steepest K, flattest K, and IOL power of nondilated eyes were measured at the initial examination and later at 6 months by the IOLMaster. Changes in AL, K, and IOL power using the SRK (Sanders, Retzlaff, and Kraff)-T formula within 6 months were compared using the paired-sample t-test. Results: The study comprised 90 eyes from 90 patients. The mean age of the patients was 62.99±13.95 years (range 28–87 years). Mean values and standard deviation for AL, steepest K, flattest K, and IOL power at initial visit and 6 months later were 23.56±1.51 mm and 23.56±1.52 mm (P=1.0; 95% confidence interval [CI] -0.01 to 0), 44.94±1.37 D and 44.98±1.43 D (P=0.96; 95% CI -0.13 to 0.04), 43.85±1.43 D and 43.89±1.36 D (P=0.93; 95% CI -0.02 to 0.07), and 20.27±4.12 D and 20.15±4.51 D (P=0.99; 95% CI -0.05 to 0.29), respectively. Conclusion: There was no statistically significant difference in AL (P=1.0), both K (P=0.96, P=0.93), or IOL power (P=0.99) within the 6-month period using the IOLMaster. Remeasurement at 6 months may be required in some cases, but should not be routine.
关键词： IOLMaster,keratometry,IOL power,axial length,cataract
更新于2025-09-23 15:22:29
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Influence of Axial Length on Thickness Measurements Using Spectral-Domain Optical Coherence Tomography
摘要： The purpose of this study was to assess the in?uence of axial length on spectral-domain optical coherence tomography (SD-OCT) thickness measurements in patients with subretinal visual implants. Data from eight emmetropic pseudophakic eyes of eight patients with subretinal visual implants were analyzed retrospectively. These patients participated in the monocentric part of a multicenter trial. The axial length was measured in three short (<22.5 mm), three medium (22.51–25.50 mm), and two long (>25.52 mm) eyes. Using Heidelberg Spectralis, the known thickness of a subretinal implant microchip (70 lm) was measured on 15 images per eye with SD-OCT, using the software calipers. The mean axial length was 20.8 6 0.8 mm in short eyes, 23.3 6 0.4 mm in medium eyes, and 26.3 6 0.5 mm in long eyes. We found in short eyes, in medium eyes, and in long eyes a mean value of microchip thickness measurements from SD-OCT of 82.9 6 1.4 lm, 70.5 6 1.3 lm, and 64.2 6 1.3 lm, respectively. The thickness measurements decreased in SD-OCT measurements with longer axial lengths signi?cantly (P < 0.0001). Axial length in?uences SD-OCT thickness measurements. Our ?ndings demonstrate accuracy of the scaling in SD-OCT thickness measurements in emmetropic medium eyes. Caution is recommended when comparing the measured values of short and long eyes with the normative database of the instrument. There is a need for larger sample-size studies to con?rm our results.
关键词： subretinal visual implant,spectral-domain optical coherence tomography (SD-OCT),axial length,Heidelberg Spectralis,in vivo measurement
更新于2025-09-23 15:21:01
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Assessing the Use of Incorrectly Scaled Optical Coherence Tomography Angiography Images in Peer-Reviewed Studies
摘要： IMPORTANCE Individual differences in axial length affect the lateral magnification of in vivo retinal images and as a result can affect the accuracy of quantitative measurements made from these images. As measurements from optical coherence tomography angiography (OCTA) images are becoming increasingly used in the diagnosis and monitoring of a wide range of diseases, evaluating which studies use correctly scaled images is crucial to their interpretation. OBJECTIVE To perform a systematic literature review to assess the percentage of articles that report correcting the scale of their OCTA images for individual differences in retinal magnification. EVIDENCE REVIEW A PubMed (MEDLINE) search was conducted for articles on OCTA retinal imaging published between June 1, 2015, and June 1, 2018. Initial results included 7552 articles. Initial exclusion criteria removed studies of animal models, as well as reviews, letters, replies, comments, and image-based or photographic essays. Articles not written in English and those that required purchase from non–English language websites were excluded. Articles that did not use OCTA for imaging the retina were also excluded. Remaining articles were reviewed in detail to assess whether the OCTA measurements required correct lateral scaling, and if so, whether axial length was reported or used to scale the images. We also determined the number of articles that mentioned the lack of correct lateral scaling as a limitation of the study. FINDINGS A total of 989 articles were included in the detailed review. Of these, 509 were determined to require correct image scaling for their analyses, but only 41 (8.0%) report measuring and using axial length to correct the lateral scale of their OCTA images. Furthermore, of the 468 articles that did not correctly scale their images, only 18 (3.8%) mentioned this as a limitation to their study. CONCLUSIONS AND RELEVANCE These findings suggest that most peer-reviewed articles in PubMed that use quantitative OCTA measurements use incorrectly scaled images. This could call into question the conclusions of such studies and warrants consideration by OCTA manufacturers, physicians, authors, journal reviewers, and journal editors.
关键词： retinal imaging,axial length,optical coherence tomography angiography,lateral scaling,OCTA
更新于2025-09-11 14:15:04
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Analysis of Factors that Influence on Accuracy of Intraocular Lens Power Calculation
摘要： To investigate which factors primarily influence refractory errors between various formulas used to calculate intraocular lens (IOL) power. Methods: Records of 266 eyes of 191 patients who underwent uneventful cataract surgery were reviewed retrospectively. IOL power was determined using SRK/T, HofferQ (H/Q), Master SRK/T (M/T), Master HofferQ (M/Q), Master Holladay (M/Hol), and Master Haigis (M/Hai). The mean absolute error (MAE) of each formula was compared; MAE was defined as the difference between the postoperative spherical equivalence (SE) determined 1 month after surgery and the predicted SE. Factors that could have influenced interformula refractive errors were analyzed. Patients were divided into 3 groups based on average keratometric value (Kavg) and the inter-group differences of the AE of each formula were analyzed. Effects of corneal curvature on changes in AE of each formula were evaluated by linear regression. Results: The MAE was minimized in the M/T formula, followed by the M/Hol, M/Hai, SRK/T, H/Q, and M/Q formulas. Interformula MAE differences were not statistically significant. Kavg and AXL were significantly influenced by the different predictive values between formulas in univariate analysis, but only AXL was significant in multivariate analysis. The AE in each formula among the 3 groups according to keratometry was significantly different in SRK, M/Hol, and M/Hai. Linear regression analysis showed a significant negative correlation between Kavg, AE of SRK/T and the MHai formula. In particular, this effect was more pronounced in those with short AXL (<22.5 mm). Conclusions: There were no significant MAE differences between formulas. AXL was a significant factor that influenced the differences between formulas. SRK/T and M/Hai may be affected by outside the normal range of corneal curvatures.
关键词： Corneal curvature,Refractive error,Intraocular lens power calculation,Axial length
更新于2025-09-09 09:28:46