Axial Length Of Eye Research Articles

Finite Element Analysis of Changes in Deformation of Intraocular Segments by Airbag Impact in Eyes of Various Axial Lengths.

We studied the kinetic phenomenon of an airbag impact on eyes with different axial lengths using finite element analysis (FEA) to sequentially determine the physical and mechanical responses of intraocular segments at various airbag deployment velocities. The human eye model we created was used in simulations with the FEA program PAM-GENERISTM. The airbag was set to impact eyes with axial lengths of 21.85 mm (hyperopia), 23.85 mm (emmetropia) and 25.85 mm (myopia), at initial velocities of 20, 30, 40, 50 and 60 m/s. The deformation rate was calculated as the ratio of the length of three segments, anterior chamber, lens and vitreous, to that at the baseline from 0.2 ms to 2.0 ms after the airbag impact. Deformation rate of the anterior chamber was greater than that of other segments, especially in the early phase, 0.2-0.4 ms after the impact (P < 0.001), and it reached its peak, 80%, at 0.8 ms. A higher deformation rate in the anterior chamber was found in hyperopia compared with other axial length eyes in the first half period, 0.2-0.8 ms, followed by the rate in emmetropia (P < 0.001). The lens deformation rate was low, its peak ranging from 40% to 75%, and exceeded that of the anterior chamber at 1.4 ms and 1.6 ms after the impact (P < 0.01). The vitreous deformation rate was lower throughout the simulation period than that of the other segments and ranged from a negative value (elongation) in the later phase. Airbag impact on the eyeball causes evident deformation, especially in the anterior chamber. The results obtained in this study, such as the time lag of the peak deformation between the anterior chamber and lens, suggest a clue to the pathophysiological mechanism of airbag ocular injury.

A pilot study of axial length changes associated with myopia control spectacles in subjects reading under mesopic conditions

PurposeTo investigate whether axial length changes in subjects wearing myopia control spectacles under mesopic conditions. MethodsYoung users of monofocal spectacles with myopic spherical equivalent ranging from −1.00 D to −5.00 D were enrolled prospectively. Subjects were tested while using a pair of special defocus spectacles with a central zone including the distance myopic correction and a peripheral zone with an addition of +3.50 D. Subjects first read an online book with black letters on white background on a desktop computer with their monofocal spectacles for 20 minutes and then read with special defocus spectacles for another 20 minutes. Reading took place in a darkened room under 20 lux illumination. Before and after these periods, axial length of the right eye was measured ten times using the Lenstar, and average measurements were recorded. ResultsThe 11 subjects in this pilot study had a mean age of 20.9 ± 7.7 years, and 1 was female. Their mean spherical equivalent of the right eyes was −3.20 ± 2.29 D. As expected, axial length increased by 8.2 ± 9.4 μm (P < 0.01) after 20 minutes of reading with monofocal spectacles in low light. When reading with defocus spectacles under the same conditions, the axial length saw an additional, nonsignificant change of 2.2 ± 12.2 μm (P = 0.56). ConclusionsWhen reading in mesopic conditions, the axial length in study subjects did not return to baseline values with myopia control spectacles.

Unexpected findings: loss of corneal endothelial cells in Uygur patients with exfoliation syndrome

PurposeThis study aimed to investigate anterior segment parameters in patients with exfoliation syndrome (XFS) and exfoliation glaucoma (XFG).MethodsThe study adopted a retrospective case series design, involving a total of 56 patients (112 eyes) with unrelated XFS/XFG (XFS: 26 patients/60 eyes; XFG: 30 patients/44 eyes) and 100 age-related cataract cases as the control group (200 eyes). The participants were evaluated at the ophthalmology department of the First Affiliated Hospital of Xinjiang Medical University. Clinical data, including eye axial length, anterior chamber depth, white-to-white distance, central corneal thickness, and corneal endothelial cell density (ECD), were collected for statistical analysis.ResultsECD exhibited a significant difference between the XFS/XFG and age-related cataract groups (P < 0.001), while the remaining indexes did not show statistical differences (P > 0.05). Ocular parameters in patients with XFS and XFG were distinct from those in age-related cataract cases, with consistent results. Notably, there were no statistically significant differences between XFS and XFG patients.ConclusionsECD is reduced in XFS/XFG patients compared with age-related cataract subjects. It is crucial to remain vigilant to enhance surgical safety in XFS/XFG patients and prevent complications proactively.

Diagnosis of posterior staphyloma using the radius of steepest curvature among retinal pigment epithelium segmentation line measured by optic coherent tomography

PurposeTo investigate a novel marker to diagnose posterior staphylomas by measuring the radius of the steepest curvature on the retinal pigment epithelium (RPE) segmentation line using optical coherence tomography (OCT).Study DesignRetrospective Cross-sectional Study.MethodsThe authors developed a prototype software to measure the radius of curvature on the RPE segmentation line of OCT. Twelve images of 9-mm radial OCT scans were used. The radius of curvature was measured at the steepest area of the RPE segmentation line, and the macular curvature (MC) index was calculated based on its reciprocal. Based on the wide-field fundus findings, the study sample was divided into three groups: definite posterior staphyloma, no posterior staphyloma, and undetermined. The differences of MC index among the groups and the correlation between the MC index, age, and axial length were analyzed.ResultsThe present study analyzed 268 eyes, with 54 (20.1%) with definite posterior staphyloma, 202 (75.4%) with no posterior staphyloma, and 12 (4.5%) with undetermined disease status. A maximum MC index of 37.5 was observed in the group with no posterior staphyloma, which was less than the minimum MC index of 42.7 observed in the group with definite posterior staphyloma. The MC index had strong correlations with the axial length and age in eyes with high myopia.ConclusionsEyes with posterior staphyloma have a steeper curvature than those with radius 8.44 mm, while eyes without posterior staphyloma do not. MC index 40 (radius 8.44 mm) might act as a reference to distinguish between those with and those without posterior staphyloma.

The relationships between lens diameter and ocular biometric parameters: an ultrasound biomicroscopy-based study.

This study aims to explore the relationships between lens diameter (LD) measured with ultrasound biomicroscopy (UBM) and ocular biometric parameters. Ocular biometric parameters including axial length (AL), white-to-white distance (WTW), anterior chamber depth (ACD), lens thickness (LT) and anterior segment length (ASL) were measured with IOL-Master 700, and the direct measurement of LD was conducted through UBM (ArcScan Insight 100). Relationships between LD and ocular biometric parameters were then investigated. Eyes with AL ≥ 28 mm were defined as eyes with extreme myopia, and eyes with AL < 28 mm were defined as eyes without extreme myopia. A total of 194 eyes from 194 subjects were included. The mean LD was 9.58 ± 0.49 mm, ranging from 8.60 to 10.96 mm. According to univariate analysis, larger LD was associated with elder age, male gender, larger WTW, ACD and ASL (all p < 0.05). Meanwhile, the LD was positively correlated with AL in eyes without extreme myopia (p < 0.05), but not in eyes with extreme myopia (p > 0.05). Backward stepwise regressions revealed that a larger LD was associated with larger WTW, ASL and AL in eyes without extreme myopia (all p < 0.05), while ASL was the only significant variable in eyes with extreme myopia (p < 0.05). Larger WTW, ASL and AL in eyes without extreme myopia, as well as longer ASL in eyes with extreme myopia indicated a larger LD, which provides guidance in personalized surgical choice and promises ideal visual outcomes.

The long and short of it: a comprehensive assessment of axial length estimation in myopic eyes from ocular and demographic variables.

Axial length, a key measurement in myopia management, is not accessible in many settings. We aimed to develop and assess machine learning models to estimate the axial length of young myopic eyes. Linear regression, symbolic regression, gradient boosting and multilayer perceptron models were developed using age, sex, cycloplegic spherical equivalent refraction (SER) and corneal curvature. Training data were from 8135 (28% myopic) children and adolescents from Ireland, Northern Ireland and China. Model performance was tested on an additional 300 myopic individuals using traditional metrics alongside the estimated axial length vs age relationship. Linear regression and receiver operator characteristics (ROC) curves were used for statistical analysis. The contribution of the effective crystalline lens power to error in axial length estimation was calculated to define the latter's physiological limits. Axial length estimation models were applicable across all testing regions (p ≥ 0.96 for training by testing region interaction). The linear regression model performed best based on agreement metrics (mean absolute error [MAE] = 0.31 mm, coefficient of repeatability = 0.79 mm) and a smooth, monotonic estimated axial length vs age relationship. This model was better at identifying high-risk eyes (axial length >98th centile) than SER alone (area under the curve 0.89 vs 0.79, respectively). Without knowing lens power, the calculated limits of axial length estimation were 0.30 mm for MAE and 0.75 mm for coefficient of repeatability. In myopic eyes, we demonstrated superior axial length estimation with a linear regression model utilising age, sex and refractive metrics and showed its clinical utility as a risk stratification tool.

Lens-induced myopization and body weight in young guinea pigs

BackgroundTo investigate the relationship between body weight and Axial length in guinea pigs.MethodsForty pigmented guinea pigs were randomly divided into two groups, namely control group and negative lens-induced myopization (LIM) group. After measuring the baseline axial length and body weight (BW), guinea pigs of LIM group received bilateral negative lens-induced myopization using − 10.0 diopters lenses. One week later, the lenses were removed and biometric and ophthalmoscopic examinations were repeated.ResultsTwo groups of guinea pigs showed no statistical difference in initial body weight and eye axis length. Compared to the control group, the lens-induced group had a lower weight (P = 0.02) and a longer axial length (P < 0.01) at the end of study Neither at baseline nor at week 1 did AL correlate with BW in both groups (Control Baseline: r = 0.306, P = 0.19; Control Week1: r = 0.333, P = 0.15; LIM Baseline: r=-0.142, P = 0.55; LIM Week 1: r = 0.189, P = 0.42). Lens-induction had a significant effect on axial elongation (P < 0.01) while body weight had no impact on such aspect (P > 0.05).ConclusionIn guinea pigs of the same age, axial length was not correlated with body weight. Also, baseline body weight had no impact on natural axial length growth or lens-induced myopia. Lens-induction caused a significant reduction in body weight gain.

The predictive value of parameters of optic disk in evaluating the progression of myopia

Aims/Purpose: To analyse the parameters of the optic nerve head (ONH) as markers of the progression of myopia with the usage of optical coherence tomography (OCT).Methods: 72 patients (144 eyes) aged 9–57 years with myopia were investigated. The standard OCT parameters of the ONH, the ovality index (OI), the zone of parapapillary atrophy (PPA), location of the lamina cribrosa (LC) of the sclera and the trunk of the central retinal vessels (CRV) were evaluated. Data was statistically approved.Results: A positive correlation between the axial length (AL) and the optic disc cup area, its horizontal and vertical diameters was found. Whilst the volume and the depth of the optic disc cup increased till the AL reached a certain critical value (26.3 mm) with subsequent reduction. An inverse correlation between the AL and the neuroretinal rim area, volume and rim/disc ratio was revealed. These changes in the ONH can be explained by scleral remodelling during elongation of the eye. Formation of γ‐zone PPA and an increase in the β‐zone PPA was accompanied by the tendency of thinning of the retinal nerve fibre layer (RNFL) in the inferior, nasal‐superior and superior sectors of the ONH. In 27.63% cases tilted optic discs were noted, of which 61.90% were vertically and 38.1% ‐ horizontally tilted. The direction of the tilt was determined by the location of the PPA zone with a tendency to thinning of the RNFL in the same sectors. A positive correlation between the AL of eye and the location of the LC of sclera was found. In 29.17% the superficial location of the LC was determined. In 54.17% elongation was accompanied by displacement of the trunk of the CRV on ONH in the nasal ‐ 71.79%, or in the superior‐nasal direction ‐ 28.21%.Conclusions: The revealed changes of optic disc cup, neuroretinal rim and the parapapillary zones; a superficial displacement of LC of sclera and ‘nasalization’ of the trunk of CRV; a decrease in the OI with growth in the AL; relationships of the PPA zone with a tendency to thinning of the RNFL and direction of the tilt can be useful as OCT markers in interpreting normative data in patients with myopia, predicting its progression, and also in differential diagnosis with glaucomatous optic neuropathy.

Are red/green colour vision deficient individuals at altered risk of myopia?

Aims/Purpose: To investigate the association between red/green colour vision deficiency (CVD) and myopia in Irish and Australian participants.Methods: Data from the Ireland Eye Study (IES; age 12–13 years), Raine Study Gen2 cohort (Australia; age 18–22 years) and Kidskin Study (Australia; age 25–30 years) were used. Colour vision was assessed with the Hardy‐Rand‐Ritler (IES) or Ishihara colour vision test (Raine, Kidskin). Right eye spherical equivalent refractive error (SER; myopia defined as SER ≤ −0.50 dioptres [D]) was measured with cycloplegic autorefraction and right eye axial length (AXL) with interferometry. Participants who were female, or with incomplete colour vision or refraction data, tritanomaly, monochromacy, previous surgery or condition‐altering refraction were excluded. Linear and logistic regression were used for analysing binary and continuous outcomes, respectively, with an interaction between study country and CVD.Results: After exclusions (n = 56), there were 2488 participants of whom 1286 (51.7%) were male (IES: n = 503, Raine: n = 676 and Kidskin: n = 107). The prevalence of CVD across the IES, Raine and Kidskin studies, respectively, was 5.8% (16 deutan, 9 protan, 5 unclassified), 5.5% (18 deutan, 3 protan, 16 unclassified) and 6.5% (6 deutan, 1 unclassified). After adjusting for age, any red/green CVD was not associated with myopia risk (odds ratio [OR] = 1.31, 95% confidence interval [95%CI]: 0.86–2.32, p = 0.36), SER or AXL. However, when analysed by CVD type, deutan CVD was associated with higher odds of myopia (OR = 2.31, 95% CI 1.19 to 4.44, p = 0.01) and a more myopic SER (difference = −0.61D, 95% CI: −1.09 to −0.12, p = 0.02; AXL: difference = 0.09 mm, 95%CI: −0.19 to 0.37, p = 0.51), compared to non‐CVD participants, while other CVD types were not associated with myopia (protan: OR = 0.94, 95% CI 0.20–4.41, p = 0.94; unclassified: OR = 0.36, 95% CI 0.08–1.56, p = 0.17), SER or AXL.Conclusions: In contrast to previous findings in Chinese school students, participants with a deutan CVD in this study had a higher risk of myopia.

Prediction of Myopia Eye Axial Elongation With Orthokeratology Treatment via Dense I2I Based Corneal Topography Change Analysis.

While orthokeratology (OK) has shown effective to slow the progression of myopia, it remains unknown how spatially distributed structural stress/tension applying to different regions affects the change of corneal geometry, and consecutive the outcome of myopia control, at fine-grained detail. Acknowledging that the underlying working mechanism of OK lens is essentially mechanics induced refractive parameter reshaping, in this study, we develop a novel mechanics rule guided deep image-to-image learning framework, which densely predicts patient's corneal topography change according to treatment parameters (lens geometry, wearing time, physiological parameters, etc.), and consecutively predicts the influence on eye axial length change after OK treatment. Encapsulated in a U-shaped multi-resolution map-to-map architecture, the proposed model features two major components. First, geometric and wearing parameters of OK lens are spatially encoded with convolutions to form a multi-channel input volume/tensor for latent encodings of external stress/tension applied to different regions of cornea. Second, these external latent force maps are progressively down-sampled and injected into this multi-scale architecture for predicting the change of corneal topography map. At each feature learning layer, we formally derive a mathematic framework that simulates the physical process of corneal deformation induced by lens-to-cornea interaction and corneal internal tension, which is reformulated into parameter learnable cross-attention/self-attention modules in the context of transformer architecture. A total of 1854 eyes of myopia patients are included in the study and the results show that the proposed model precisely predicts corneal topography change with a high PSNR as 28.45dB, as well as a significant accuracy gain for axial elongation prediction (i.e., 0.0276 in MSE). It is also demonstrated that our method provides interpretable associations between various OK treatment parameters and the final control effect. Our project code package is available at https://github.com/Rongdingyi/PhyIntNet.

Double-step calculation of the intraocular lens power in lens opacities excluding the measurement of axial eye length by optical biometry. A clinical case

The main source of intraocular lens (IOL) power calculation errors in phacoemulsification (PE) is axial length (AL) measurement inaccuracy in cases if optical biometry cannot be used.bto describe an original double-step method of IOL power calculation in lens opacities which exclude AL measurement with optical biometry.Material and methods. Patient S. (male, 71) with a bilateral immature cataract underwent right eye phacoemulsification (PE) with no IOL implantation. After that, AL was measured in the aphakic state with transparent optical media and used in combination with preoperative anterior segment biometry data to calculate the IOL power. In the second stage, a selected lens with an extended focus range was implanted.Results. The patient was examined and discharged on the second day after surgery with visual acuity OD 0.3 sph +0.25 cyl -0.75 ax150 = 0.5 and signs of moderate postoperative keratopathy. After 2 weeks, uncorrected visual acuity was as high as 0.9 and could not be further corrected by spectacle lenses. The patient was admitted for surgical treatment of the left eye cataract and also operated in two stages. The AL measured by the optical method in the aphakic state, was 0.31 mm less than that measured before the operation. Six months after PE with IOL implantation, distance visual acuity in both eyes was 1.2, the patient could use binocular vision for reading and PC work with no difficulty.Conclusion. The double-step approach to IOL power calculation is justified in cases of strong decrease of crystalline lens transparency, especially in complicated cases, for example, in high myopia or “premium” lens implantation, in which patients are especially sensitive to correct target refraction, even though this approach requires a delayed IOL implantation, which should take place after a precise calculation of AL taken in the aphakic state.

Myopic Progression of Children in RSUP Dr M Djamil During COVID-19 Pandemic

Background: Myopia (nearsightedness) is an eye condition when a far object reflection is focused in front of the retina without accommodation, so far object cannot be seen clearly. The elongation of the eye's axial length primarily causes myopia. Lack of outdoor activities and excessive near work (screentime) during home confinement duringthe COVID-19 pandemic have increased the risk of myopia development, primarily in school children.&#x0D; Objective: This study aims to see children's myopic progression during the COVID-19 pandemic.&#x0D; Methods: This research was an observational analytic study by a retrospective cohort about children's myopic progression based on the difference between the spherical equivalent (SE) of 34 patients in RSUP Dr. M. Djamil from before (September 2019–February 2020) followed up to late (September 2021–February 2022) of COVID-19 pandemic from their medical records.&#x0D; Results: The results showed that myopic progression majorly occurredin children who were females (47.0%), had myopic parents (67.6%), ≥ 2 hours of outdoor activity (61.7%), &gt; 5 hours of screentime (79.4%); with slow annualized myopic progression (61.7%). The median of SE from before and late the COVID-19 pandemic are -4.00 (-16.00 – -0.25) D and -4.62 (-17.00 – -0.25) D respectively; p&lt;0.001.&#x0D; Conclusion: Children did have myopia worsening during the COVID-19 pandemic.&#x0D; Keywords: Myopia, Progression, COVID-19, Children, Spherical Equivalent

Comparison of ocular biometry and intraocular lens power using a novel biometer and a traditional biometer

The implantation of an intraocular lens (IOL) is the gold standard in today's cataract surgery. Calculating the power of the intraocular lens (IOL) has emerged as a central concern in cataract surgery over the last decade. The study aims to investigate the relationship between optical biometry and applanation ultrasound measurement of the eye's axial length. This prospective cohort study was done on 60 eyes from sixty patients undergoing phacoemulsification with primary intraocular lens implantation and scheduled for cataract surgery in the Ophthalmology Department of al-Imam al-Sadeq Hospital. Thirty eyes of patients were measured by ultrasound measurement (by A-Scan, Group 1) and the other thirty eyes by optical biometry (by IOL Master, Group 2). In Group 1There were 14 eyes of 14 males (47%) and 16 eyes of 16 females (53%) with a mean age was 71.6 ±4.33years. In Group 2, there were 16 eyes of 16 males (53%) and 14 eyes of fourteen females (47%), and the mean age of the patients in this Group was 66.13±8.61 years. The mean IOL of the patient in Group I was (19.96±1.81). At the same time, the mean IOL potent ion of the patient in Group II was (22.96±1.66). Keywords: Optical Biometry, Ultrasound Biometry, Intraocular lens (IOL), IOL Master partial coherence interferometry (PCI)

Influence of Ocular Biometry Parameters on the Predictive Accuracy of IOL Power Formulas in Patients with High Myopia.

The aim of this study was to investigate the influence of ocular biometry parameters on the predictive accuracy of 10 intraocular lens (IOL) power formulas in patients with high myopia (HM). We analyzed 202 eyes of 202 patients. The ocular biometry was determined preoperatively using an IOLMaster700. The associations between the biometry parameters and the prediction error (PE) 1month postoperatively were assessed. HM was defined as an axial length exceeding 26.50mm. In patients with HM (n = 108), the K6, Emmetropia Verifying Optical (EVO), Olsen, and Barrett UniversalII (BUII) formulas had the lowest absolute PEs among the 10 formulas. The ocular biometry parameters were not associated with the PE of K6, EVO, Olsen, or BUII. A longer axial length in HM eyes was associated with myopic outcomes by Kane, Hoffer QST, and VRF and hyperopic outcomes by Holladay2 and T2. Steeper keratometry, a deeper anterior chamber, and a thicker lens were associated with a hyperopic shift in HM eyes when using VRF, Kane, and Hoffer QST, respectively. In patients without HM (n = 94), there was no difference between the formulas in absolute PE. The significant associations between the biometry parameters and PE in patients with HM were not present in patients without HM. K6, EVO, Olsen, and BUII displayed high accuracy in HM eyes and were not influenced by preoperative biometry parameters. For the remaining formulas, the preoperative keratometry, anterior chamber depth, lens thickness, and axial length were possible error sources underlying an inaccurate IOL power prediction in patients with HM.

Refractive Status after Phacoemulsification with Biometry Done by Haigis and SRK-T Formulae in Myopic Patients

Background: Optimum refractive outcome is the key indicator for assessing the success of cataract surgery. Accurate biometric calculation of IOL is an important contributor of post-operative refractive status. There are several formulae for calculation of IOL power depending on axial length of eyes. Haigis is the formula of choice for calculating IOL power in myopic patients, whereas, SRK-T is a versatile formula irrespective of axial length. For IOL power calculation by Haigis formula needs expensive instrument. On the other hand, biometry by SRK-T formula can be done by less expensive and easily available instrument. Objective: To assess and compare post-operative refractive status after phacoemulsification where biometry done by Haigis and SRK-T formulae. Methods: This prospective observational study was conducted over 60 diagnosed patients of cataract with axial length more than 24 mm attending in the cataract clinic of NIO&amp;H for phacoemulsification. Patients were selected based on specific selection criteria. Selected patients underwent detail ophthalmic and systemic examination as well as relevant investigation. Biometric calculation of IOL power was done by a single skilled technician by using Haigis formula (group A) in 30 patients and SRK-T formula (group B) in 30 patients. Visual acuity was assessed by LogMAR unit after 4 weeks of surgery and compared between two groups, p value ≤0.05 was considered as significant. Results: Mean age of the study subjects were 57.7±6.0 (SD) years in group A and 57.27±5.48 (SD) years in group B. In group A 14(46.7%) were male and 16(53.3%) were female and in group B 16(53.3%) were male and 14(46.7%) were female. Mean axial length was 25.05±0.45 (SD) mm in group A and 24.88±0.32 (SD) mm in group B. Mean IOL power was 18.23±0.76 (SD) diopter in group A and 18.23±0.65 (SD) diopter in group B. Post-operative mean visual acuity was 0.19±0.26 (SD) LogMAR unit in group A and 0.18 ±0.27 (SD) LogMAR unit in group B. Regarding post-operative refractive status of the study subjects, in group A, out of 30 patients 14(46.7%) were emmetropic, 7(23.3%) were myopic, 5(16.7%) were hypermetropic and the rest 4(13.3%) patients had astigmatism and in group B, out of 30 patients 16(53.3%) were emmetropic, 5(16.7%) were myopic, 4(13.3%) were hypermetropic and the rest 5(16.7%) patients had astigmatism. Conclusion: Quantitative assessment and statistical analysis shows there was no significant difference in post-operative refractive status and mean visual acuity between two groups. J.Natl.Inst.Ophthalmol.2023;6(1): 42-47

Contrast Sensitivity of ON and OFF Human Retinal Pathways in Myopia.

The human visual cortex processes light and dark stimuli with ON and OFF pathways that are differently modulated by luminance contrast. We have previously demonstrated that ON cortical pathways have higher contrast sensitivity than OFF cortical pathways and the difference increases with luminance range (defined as the maximum minus minimum luminance in the scene). Here, we demonstrate that these ON-OFF cortical differences are already present in the human retina and that retinal responses measured with electroretinography are more affected by reductions in luminance range than cortical responses measured with electroencephalography. Moreover, we show that ON-OFF pathway differences measured with electroretinography become more pronounced in myopia, a visual disorder that elongates the eye and blurs vision at far distance. We find that, as the eye axial length increases across subjects, ON retinal pathways become less responsive, slower in response latency, less sensitive, and less effective and slower at driving pupil constriction. Based on these results, we conclude that myopia is associated with a deficit in ON pathway function that decreases the ability of the retina to process low contrast and regulate retinal illuminance in bright environments.

Relationship between the structure and microcirculation of the optic disc region and myopic traction maculopathy in highly myopic eyes

PurposeTo explore the characteristics and influencing factors structural and microcirculatory of optic disc and peripapillary tissue in eyes with myopia traction maculopathy (MTM).MethodsThere were 100 eyes from 77 patients in this study. We used 1:1 matching axial length in myopic eyes. Patients were divided into two groups according to the presence or absence of MTM. Fundus structure parameters were obtained by swept source optical coherence tomography (SS-OCT), and the optic disc microcirculation parameters were obtained by OCT angiography (OCTA).ResultsMTM group were older (P = 0.001) and had poorer Best-corrected Visual Acuity (BCVA) (P = 0.011), the optic disc-fovea distance (DFD) was longer (P < 0.019), optic disc tilt was greater (P < 0.001), area of peripapillary atrophy (PPA) was larger (P < 0.001), and PPA/optical disc area (ONH) was higher (P < 0.001). The peripapillary scleral thickness (PST) was lower in the MTM group (P < 0.001). The mean peripapillary choroidal thickness (PCT) (P < 0.001) and PCT in the 10 orientations were significantly lower in the MTM group than in the NMTM group (all P < 0.01). Vascular density in the nasosuperior (NS) region of the optic disc was significantly lower in the MTM group (P = 0.037). The generalized estimating equation suggested that PPA area (P = 0.028), mean PCT (P = 0.008), superior PCT (P = 0.027), inferonasal PCT (P = 0.040), temporoinferior PCT (P = 0.013), and PST (P = 0.046) correlated with MTM. Age, axial length, optic disc tilt, PPA area, mean PCT, and optic disc central zone (0–2 mm) vascular density (all P < 0.05) were significantly correlated with PST.ConclusionsThe enlarged PPA area and thinner PCT and PST in eyes with MTM are more significant. Lower PST in high myopia was related to abnormalities of PCT and microcirculation.Trial registrationClinical Trial Registration number: ChiCTR2100046590

Panretinal Optical Coherence Tomography.

We introduce a new concept of panoramic retinal (panretinal) optical coherence tomography (OCT) imaging system with a 140° field of view (FOV). To achieve this unprecedented FOV, a contact imaging approach was used which enabled faster, more efficient, and quantitative retinal imaging with measurement of axial eye length. The utilization of the handheld panretinal OCT imaging system could allow earlier recognition of peripheral retinal disease and prevent permanent vision loss. In addition, adequate visualization of the peripheral retina has a great potential for better understanding disease mechanisms regarding the periphery. To the best of our knowledge, the panretinal OCT imaging system presented in this manuscript has the widest FOV among all the retina OCT imaging systems and offers significant values in both clinical ophthalmology and basic vision science.

Effect of COVID-19 Pandemic on Myopia Progression in Pediatric Patients Treated with Atropine Eyedrops

Purpose: We investigated the impact of the COVID-19 pandemic on myopia progression in pediatric patients who received low-dose atropine (0.01%) eye drops.Methods: We retrospectively analyzed the medical records of pediatric patients who received ≥ 12 months of low-dose atropine (atropine sulfate 0.01%) eye drops for myopia. The beginning of the COVID-19 pandemic was defined as February 2020. Patients were divided into two groups for comparative analysis. Patients in group A received low-dose atropine for ≥ 12 months between July 2013 and January 2020, whereas patients in group B received low-dose atropine between February 2020 and July 2021; atropine eye drops were administered once daily. The spherical equivalent and axial length of the right eye were measured at the initiation of treatment and after 12 months.Results: Among the 72 patients, 34 in group A received low-dose atropine before the COVID-19 pandemic, whereas 38 in group B received low-dose atropine after the COVID-19 pandemic. After 12 months of treatment with low-dose atropine eye drops, the changes in spherical equivalent were -0.58 ± 0.47 diopters (D) in group A and -0.84 ± 0.56 D in group B (p = 0.045). Moreover, the changes in axial length were 0.30 ± 0.23 mm in group A and 0.50 ± 0.31 mm in group B (p = 0.011).Conclusions: The efficacy of low-dose atropine eye drops in pediatric myopia patients has decreased since the beginning of the COVID-19 pandemic.

Effect of vascular endothelial growth factor 165 on dopamine level in the retinas of guinea pigs with form-deprivation myopia.

Myopia is the most common refractive error because excessive increase in the axial length of a myopic eye leads to the thinning of the posterior scleral pole and can cause serious complications resulting in blindness. Thus, myopia has become a great concern worldwide. Dopamine (DA) plays a role in the development of myopia. Moreover, in Parkinson's disease, it has been proved that vascular endothelial growth factor 165 (VEGF165) can promote the survival and recovery of DA neurons, resulting in increased DA secretion in the striatum, thereby treating neuropathy. Therefore, we speculate that VEGF165 can also promote the release of DA in the retina to inhibit the occurrence and development of myopia. We aimed to investigate the effect of VEGF165 on DA levels in the retinas of guinea pigs with form-deprivation myopia (FDM) and the effects of DA on myopia prevention and control. Healthy 3-week-old pigmented guinea pigs were randomly divided into blank, FDM, phosphate buffer saline (PBS), 1, 5, and 10 ng groups. The FDM model was established by covering the right eye continuously with a translucent latex balloon pullover for 14 days. The pigs in the PBS, 1, 5, and 10 ng groups were injected with PBS buffer and 1, 5, and 10 ng of VEGF165 recombinant human protein, respectively, in the vitreous of the right eye before masking. The refractive error and axial length were measured before and after modeling. All retinas were used for biomolecular analyses after 14 days. We found that the intravitreal injection of VEGF165 elevated DA levels in the retina and was effective in slowing the progression of myopia, and 1 ng of VEGF165 was the most effective. Moreover, the number of vascular endothelial cell nuclei in the 1 ng group was lower than that in the other VEGF165 groups. Our data suggest that VEGF165 has a promoting effect on DA in the retinas of guinea pigs with FDM, potentially controlling the development of myopia.