Refractive Change Research Articles

Refractive Error Change and Overminus Lens Therapy for Childhood Intermittent Exotropia

Increased myopic shift was found to be associated with 1 year of overminus spectacle treatment for children with intermittent exotropia (IXT). Persistence of myopic shift after discontinuing overminus spectacles is unknown. To compare refractive error change over 3 years in children with IXT originally treated with overminus vs nonoverminus spectacles. This study was an 18-month extension of the Trial of Overminus Spectacle Therapy for Intermittent Exotropia cohort, which previously randomized children aged 3 to 10 years with IXT and baseline spherical equivalent refractive error (SER) between -6.00 diopters (D) and 1.00 D to overminus spectacles (-2.50 D for 12 months, -1.25 D for 3 months, and nonoverminus for 3 months) or nonoverminus spectacles. Children were recruited from 56 sites from July 2010 to February 2022. Data were analyzed from February 2022 to January 2024. After trial completion at 18 months, participants were followed up at 24 and 36 months. Treatment was at investigator discretion from 18 to 36 months. Change in SER (cycloplegic retinoscopy) from baseline to 36 months. Of 386 children in the Trial of Overminus Spectacle Therapy for Intermittent Exotropia, 223 (57.8%) consented to 18 months of additional follow-up, including 124 of 196 (63.3%) in the overminus treatment group and 99 of 190 (52.1%) in the nonoverminus treatment group. Of 205 children who completed 36-month follow-up, 116 (56.6%) were female, and the mean (SD) age at randomization was 6.2 (2.1) years. Mean (SD) SER change from baseline to 36 months was greater in the overminus group (-0.74 [1.00] D) compared with the nonoverminus group (-0.44 [0.85] D; adjusted difference, -0.36 D; 95% CI, -0.59 to -0.12; P = .003), with 30 of 112 (26.8%) in the overminus group having more than 1 D of myopic shift compared with 14 of 91 (15%) in the nonoverminus group (risk ratio, 1.8; 95% CI, 1.0-3.0). From 12 to 36 months, mean (SD) myopic shift was -0.34 (0.67) D and -0.36 (0.66) D in the overminus and nonoverminus groups, respectively (adjusted difference, -0.001 D; 95% CI, -0.18 to 0.18; P = .99). The greater myopic shift observed after 1 year of -2.50-D overminus lens treatment remained at 3 years. Both groups had similar myopic shift during the 2-year period after treatment weaning and cessation. The risk of myopic shift should be discussed with parents when considering overminus lens treatment. ClinicalTrials.gov Identifier: NCT02807350.

Altering optical zone diameter, reverse curve width, and compression factor: impacts on visual performance and axial elongation in orthokeratology

PurposeTo investigate the effects of modifications in back optical zone diameter (BOZD), reverse curve width (RCW), and compression factor (CF) on refractive error changes and axial elongation in myopic children undergoing orthokeratology (ortho-k) over a 12-month period. MethodIn this retrospective study, data from 126 myopic children undergoing ortho-k fitting were analyzed. Subjects were categorized into four distinct groups based on lens design parameters: Group A (BOZD 6.0 mm, RCW 0.6 mm, CF 0.75 D); Group B (BOZD 6.0 mm, RCW 0.6 mm, CF 1.25 D); Group C (BOZD 5.4 mm, RCW 0.9 mm, CF 1.25 D); and Group D (BOZD 5.0 mm, RCW 1.1 mm, CF 1.25 D). The study evaluated uncorrected visual acuity (UCVA), corneal topography, and axial length (AL) at intervals, using Linear Mixed Models (LMMs) for time-based changes, and ANOVA or Kruskal-Wallis tests for group differences in AL elongation. A multivariable regression analysis identified factors independently associated with AL elongation. ResultsWithin the first day and week, all four groups displayed significant improvements in UCVA and alterations in corneal curvature, which subsequently stabilized. Although UCVA variations between groups were subtle, Group D had less corneal curvature change than Groups A and B initially and exhibited significantly less AL elongation after one year. No significant difference in corneal curvature change or AL elongation was observed between Group C and the other groups. Multiple regression analysis indicated that older baseline age, greater baseline spherical equivalent refractive error, and smaller BOZD were associated with less AL elongation. ConclusionThe study reveals a positive correlation between BOZD and axial length growth over the 12-month period. A pure 0.5 D CF increment demonstrates a nonsignificant impact. This study provides new ideas into optimizing the parameters of ortho-k lenses.

Controllable Modulation of Third‐Order NLO Properties by Polymer‐Modified MOFs Core@Shell Nanoarchitecture

AbstractThe delocalization and rearrangement of π electron clouds in space is the crucial source of regulating nonlinear optical (NLO) performance. Herein, a core‐shell metal organic framework (MOF)‐heterojunction is constructed to achieve the effect of tuning NLO properties by promoting charge transfer through multiple interactions between heterogeneous interfaces. [Cd(L)(4,4′‐bpy)(H2O)]n (Cd‐MOF) is selected to coat on polyaniline (PANI) surface to form PANI@Cd‐MOF. The constructed heterojunction displays an enhanced reverse saturation absorption (RSA) signal compared with Cd‐MOF, and it should be noted that the third‐order NLO refractive behavior changes from the self‐defocusing of Cd‐MOF to the self‐focusing of PANI@Cd‐MOF. It is proposed that high‐speed electronic communication bridges established via the rich hydrogen bond network (O… H‐N) and π–π interactions between heterogeneous interfaces can effectively modify the π electron cloud density that finally regulates the NLO properties. This work is believed to provide new avenues and insights for the design of third‐order NLO materials.

Study of myopia progression and risk factors in Hubei children aged 7–10 years using machine learning: a longitudinal cohort

BackgroundTo investigate the trend of refractive error among elementary school students in grades 1 to 3 in Hubei Province, analyze the relevant factors affecting myopia progression, and develop a model to predict myopia progression and the risk of developing high myopia in children.MethodsLongitudinal study. Using a cluster-stratified sampling method, elementary school students in grades 1 to 3 (15,512 in total) from 17 cities in Hubei Province were included as study subjects. Visual acuity, cycloplegic autorefraction, and height and weight measurements were performed for three consecutive years from 2019 to 2021. Basic information about the students, parental myopia and education level, and the students’ behavioral habits of using the eyes were collected through questionnaires.ResultsThe baseline refractive errors of children in grades 1 ~ 3 in Hubei Province in 2019 were 0.20 (0.11, 0.27)D, −0.14 (−0.21, 0.06)D, and − 0.29 (−0.37, −0.22)D, respectively, and the annual myopia progression was − 0.65 (−0.74, −0.63)D, −0.61 (−0.73, −0.59)D and − 0.59 (−0.64, −0.51)D, with the prevalence of myopia increasing from 17.56%, 20.9%, and 34.08% in 2019 to 24.16%, 32.24%, and 40.37% in 2021 (Χ2 = 63.29, P < 0.001). With growth, children’s refractive error moved toward myopia, and the quantity of myopic progression gradually diminished. (F = 291.04, P = 0.027). The myopia progression in boys was less than that in girls in the same grade (P < 0.001). The change in spherical equivalent refraction in myopic children was smaller than that in hyperopic and emmetropic children (F = 59.28, P < 0.001), in which the refractive change in mild myopia, moderate myopia, and high myopia children gradually increased (F = 73.12, P < 0.001). Large baseline refractive error, large body mass index, and high frequency of eating sweets were risk factors for myopia progression, while parental intervention and strong eye-care awareness were protective factors for delaying myopia progression. The nomogram graph predicted the probability of developing high myopia in children and found that baseline refraction had the greatest predictive value.ConclusionMyopia progression varies by age, sex, and myopia severity. Baseline refraction is the most important factor in predicting high myopia in childhood. we should focus on children with large baseline refraction or young age of onset of myopia in clinical myopia prevention and control.

Low-level red-light therapy as a novel modality for myopia control in children: A systematic review

Background Due to the COVID-19 pandemic causing a rise in digital technology use, online e-learning, and decreased outdoor time, the prevalence of myopia is expected to increase. Therefore, finding an effective strategy for myopia progression control is of high importance. Low-level red-light therapy (LLRT) has been proposed as a new modality in myopia progression control. &#x0D; Objective To assess the efficacy of LLRT for myopia control in children.&#x0D; Methods A comprehensive literature search of four online databases (PubMed, Cochrane, ProQuest, and WorldCat) was performed. We included original studies that assessed the efficacy of LLRT for myopia control in children and excluded animal studies, case reports, articles with no full-text available, and articles not in English. Risk of bias assessment was performed using different tools according to the study type. The main outcome measurements were changes in axial length (AL) and spherical equivalent refraction (SER).&#x0D; Results Three clinical studies, two randomized controlled trials and one retrospective cohort study, were reviewed. A total of 296 children in the treatment group were evaluated. Children using single-vision spectacle only or orthokeratology lenses were evaluated for comparison. All studies had reported significantly improved outcomes, with lower mean AL changes and greater SER improvement in the LLRT group compared to the control group (P&lt;0.001 in all studies).&#x0D; Conclusion Although studies on LLRT are still limited, the treatment has shown promising results for myopia control in children. More studies to evaluate the efficacy of this new strategy are needed.

Predicting myopic changes in children wearing glasses using the Plusoptix photoscreener

IntroductionWith high increase in myopia prevalence, we aimed to assess whether Plusoptix_A09 can be used in myopic children over spectacles to predict visual acuity (VA) and myopic refraction changes.MethodsMyopic children underwent a complete ophthalmological examination. Plusoptix_A09 was performed over spectacles. VA changes, refraction changes and time since previous glasses prescription, were determined. Age, current or past history of amblyopia, presence of strabismus and self-perception of VA changes were registered.ResultsIn total, 199 patients were included. Spherical power (SP) and spherical equivalent (SE) measured by Plusoptix_A09 over spectacles predicted both VA changes (p < 0.001) and refraction changes (p < 0.001). Values of SP < − 0.06D or SE < − 0.22D indicated a VA decrease (AUC > 0.9, p < 0.01) for sensitivity and specificity of 85.1%, 82.1% and 82.6%, 83.3%, respectively. Age and ophthalmological comorbidities did not influence Plusoptix_A09 measurements (p > 0.05). Plusoptix_A09 over spectacles was a stronger predictor of VA changes when compared to children's self-perception, either in 4–9-year-old patients (p < 0.001 versus p = 0.628) and in 10–18-year-old children (OR < = 0.066 versus OR = 0.190). A decrease in SP and SE of − 0.10D in Plusoptix_A09 predicted a myopia progression of − 0.04D and − 0.05D, respectively.Conclusion/RelevanceThis study unveiled new features for the Plusoptix, a worldwide available photoscreener used inamblyopia screening. When Plusoptix is performed in children with their glasses on, it can rapidly predict myopia progression.For each decrease of − 0.10D in Plusoptix, a myopia progression of -0.05D is expected. Moreover, Plusoptix is more reliablethan children's self-perception of visual acuity changes, making it a useful tool either in primary care or ophthalmologypractice

THE RELATION BETWEEN SMARTPHONE USAGE IN CHANGES OF OCULAR BIOMETRY COMPONENTS AND REFRACTION AMONG ELEMENTARY SCHOOL CHILDREN

Abstract&#x0D; Introduction &amp; Objectives : Digital media is currently being increasingly used in recent years. The development of the visual system begins as soon as a child is born through visual stimulation and interaction with the environment that develops comprehensively with the general development of children. Smartphone usage affects eye developmental process. Explain the effect of ocular biometry components and refraction change in elementary school children due to duration of smartphone usage&#x0D; Methods : A one-year cohort prospective study was taken on 6-8-year-old children in the selected elementary school in South Sulawesi, Indonesia divided into two groups focused on the duration of smartphone usage and its relationship to changes in ocular biometric components and refraction.&#x0D; Results : The ocular biometry will develop in 6 and 12 months. The axial length, corneal diameter, keratometry, central corneal thickness, anterior chamber depth increased, spherical equivalent experienced a myopic shift, while the lens thickness decreased. Smartphone usage of more 3 hours had a significant difference compared to smartphone usage less than 3 hours in changes in the axial length of the eyeballs at 6 and 12 months, spherical equivalent on examination 12 (p&lt;0.05), while other tests were not significant (p&gt;0.05).&#x0D; Conclusion : Smartphone usage more than three hours per day will cause a significant change in ocular biometry and refraction

Anatomical and Functional Outcomes of Management Pediatric Retinal Detachment with High Myopia and History of Retinopathy of Prematurity: A Case Report

Introduction : To report the anatomical and functional outcomes of management of pediatric retinal detachment in children with high myopia and a history of retinopathy of prematurity.&#x0D; Case Illustration : A 9-year-old boy had a sudden visual loss two months ago. The complaint is accompanied by photopsia and floaters. No history of trauma or infection. He had a history of myopia (S-6.00) and ROP in both eyes. The VA of the right eye was no light perception, and the left eye was 1/60. A retinal detachment with the macula off was discovered in the posterior examination. The axial length was 21 mm. He underwent a scleral buckle with vitrectomy and internal limiting membrane (ILM) peeling for his left eye. After surgery, the visual acuity was 3/60 with the retina attached. Re- detachment was found three weeks after surgery. The patient was scheduled for a second phacoemulsification and vitrectomy surgery. One month later, the best visual acuity reaches 6/48 with S -8.00 D on his left eye. The complication of high intraocular pressure (IOP) after surgery was managed successfully.&#x0D; Discussion :&#x0D; Conclusion : Management of retinal detachment cases in children is challenging. Hence, a thorough understanding is crucial in order to achieve anatomical and functional success. Myopia in ROP eyes was mainly lenticular, with an alteration in the anterior chamber that contributed to the patient's refractive status change. We encourage preterm patients to have regular follow-up not only for refractive status but also for structural changes in the anterior segment until adolescence.

FEA-Based Stress-Strain Barometers as Forecasters for Corneal Refractive Power Change in Orthokeratology.

To improve the effectivity of patient-specific finite element analysis (FEA) to predict refractive power change (RPC) in rigid Ortho-K contact lens fitting. Novel eyelid boundary detection is introduced to the FEA model to better model the effects of the lid on lens performance, and stress and strain outcomes are investigated to identify the most effective FEA components to use in modelling. The current study utilises fully anonymised records of 249 eyes, 132 right eyes, and 117 left eyes from subjects aged 14.1 ± 4.0 years on average (range 9 to 38 years), which were selected for secondary analysis processing. A set of custom-built MATLAB codes was built to automate the process from reading Medmont E300 height and distance files to processing and displaying FEA stress and strain outcomes. Measurements from before and after contact lens wear were handled to obtain the corneal surface change in shape and power. Tangential refractive power maps were constructed from which changes in refractive power pre- and post-Ortho-K wear were determined as the refractive power change (RPC). A total of 249 patient-specific FEA with innovative eyelid boundary detection and 3D construction analyses were automatically built and run for every anterior eye and lens combination while the lens was located in its clinically detected position. Maps of four stress components: contact pressure, Mises stress, pressure, and maximum principal stress were created in addition to maximum principal logarithmic strain maps. Stress and strain components were compared to the clinical RPC maps using the two-dimensional (2D) normalised cross-correlation and structural similarity (SSIM) index measure. On the one hand, the maximum principal logarithmic strain recorded the highest moderate 2D cross-correlation area of 8.6 ± 10.3%, and contact pressure recorded the lowest area of 6.6 ± 9%. Mises stress recorded the second highest moderate 2D cross-correlation area with 8.3 ± 10.4%. On the other hand, when the SSIM index was used to compare the areas that were most similar to the clinical RPC, maximum principal stress was the most similar, with an average strong similarity percentage area of 26.5 ± 3.3%, and contact pressure was the least strong similarity area of 10.3 ± 7.3%. Regarding the moderate similarity areas, all components were recorded at around 34.4% similarity area except the contact pressure, which was down to 32.7 ± 5.8%. FEA is an increasingly effective tool in being able to predict the refractive outcome of Ortho-K treatment. Its accuracy depends on identifying which clinical and modelling metrics contribute to the most accurate prediction of RPC with minimal ocular complications. In terms of clinical metrics, age, Intra-ocular pressure (IOP), central corneal thickness (CCT), surface topography, lens decentration and the 3D eyelid effect are all important for effective modelling. In terms of FEA components, maximum principal stress was found to be the best FEA barometer that can be used to predict the performance of Ortho-K lenses. In contrast, contact pressure provided the worst stress performance. In terms of strain, the maximum principal logarithmic strain was an effective strain barometer.

Postoperative longitudinal refractive changes in children younger than 8 years with ectopia lentis and Marfan syndrome.

To evaluate the postoperative longitudinal refractive changes in children younger than 8 years with ectopia lentis and Marfan syndrome (MFS). Zhongshan ophthalmic center, Guangzhou, China. Retrospective cohort study. Medical data of patients diagnosed with ectopia lentis and MFS that underwent surgery younger than 8 years were collected. Refractive errors and ocular biometric parameters were collected preoperatively and at each follow-up visit. Patients were stratified into groups according to age at surgery, and only the eye operated on first was selected. Multivariate analysis was performed to determine the association between refractive shift and potential risk factors. In total, 54 eyes of 54 patients were enrolled. The median age at surgery was 6.21 years (interquartile range [IQR], 5.25 to 6.85), and the median follow-up was 2.0 years (IQR, 1.2 to 2.8 years). At age 8 years, patients demonstrated a median myopic shift ranged from -1.75 diopters (D) (IQR, -2.75 to -1.00 D) for the 4-year-old group to -0.13 D (IQR, -0.50 to -0.06 D) for the 7-year-old group. Multivariate analysis showed that greater myopic shift was associated with younger age at surgery ( P = .004), male sex ( P = .026), and shorter preoperative axis length ( P = .005). A tendency toward increasing postoperative myopic was demonstrated in children with ectopia lentis and MFS, with the greatest myopic shift in the younger age groups. If the goal is to reach emmetropia by age 8 years, the immediate postoperative hypermetropic targets should be 1.75 D for age 4 years, 1 D for age 5 years, 0.5 D for age 6 years, and 0 to 0.25 D for age 7 years.

Ray-Tracing Customization in Myopic and Myopic Astigmatism LASIK Treatments for Low and High Order Aberrations Treatment: 2-Year Visual Function and Psychometric Value Outcomes of a Consecutive Case Series.

The safety and long-term efficacy of automated ray-tracing customized myopic and myopic astigmatic femtosecond laser-assisted LASIK. This consecutive case series retrospective analysis, of 20 subjects (40 eyes) treated with automated raytracing named Wavelight Plus, to include low and high order aberrations based on a three-dimensional custom virtual eye for each case-calculated from interferometry data-obtained from a single diagnostic device that also provides Hartman-Shack Wavefront and Scheimpflug tomography data. We evaluated before and after the customized LASIK procedure: visual acuity, refractive error, high order aberrations, contrast sensitivity, and psychometric post-operative visual function data. At 24 months, the comparison of the pre-operative to the post-operative refractive and visual function value changes in average were: subjective manifest refraction from -4.38 ± 2.54 diopters (D) (range -9.75 to -1.25 D) to +0.11 ± 0.19 D; subjective manifest refractive astigmatism from -0.76 ± 0.91 D (range -2.75 to 0 D) to -0.13 ± 0.16 D, corneal astigmatism from -1.16 ± 0.64 D (range -0.2 to -2.8) to -0.47 ± 0.11 D. 65% of the eyes studied demonstrated an increase of at least one line of vision, while from the same group 38% demonstrated 2 lines of increase. High order aberrations, contrast sensitivity as well as the subjective psychometric input based on the VFQ-25 questionnaire demonstrated actual improvement. This longer-term follow-up, single-arm retrospective consecutive case series documents LASIK treatment customization that appears to be safe and effective in the correction of myopia and myopic astigmatism. Markedly improved objective and subjective visual function post-operatively, underlying the potential importance of simultaneously attempting to correct high order aberrations and improving the spatial alignment of total, measured human eye optics.

Long-term Prevalence of Opacification of a Hydrophylic Acrylic Rotationally Asymmetric Refractive Multifocal Intraocular Lens.

To determine the prevalence of opacification of a hydrophylic intraocular lens (IOL) with hydrophobic coverage and the percentage of explantations required, determining possible risk factors associated with these opacifications. This ambispective study enrolled 575 eyes of 296 patients (age 36 to 87 years) that underwent cataract surgery between 2010 and 2017 with implantation of different models of Lentis Mplus IOLs: LS-312-MF30, LS-313-MF15, LS-313-MF30, LU-313-MF30, and LU-313-MF30T (Oculentis GmbH). Visual, refractive, and slit-lamp biomicroscopic changes were evaluated in a long-term follow-up. The percentage of cases with IOL opacification and the percentage of cases in which IOL explantation was required due to such opacifications were calculated at each visit. Five of the explanted IOLs from this series could be analyzed by scanning electron microscopy (SEM-EDX). IOL opacification developed in 63 eyes (11.0%). With 95% confidence, the prevalence of IOL opacification was between 842 and 1,401 cases per 10,000 eyes. The time elapsed between surgery and the presence of IOL opacification ranged between 0 and 9.3 years (mean: 4.7 ± 2.2 years). No significant differences in terms of IOL opacification rate were found according to gender (P = .378). No significant differences were found in arterial hypertension, diabetes, hypothyroidism, or hyperthyroidism rates between eyes with or without IOL opacification (P ≥ .053). IOL explantation was needed in 9 eyes (1.57%). SEM-EDX analysis confirmed the presence of rough areas on the IOL surface containing different components, such as calcium, phosphorous, copper, or nitrogen. The prevalence of opacification with time in Lentis Mplus IOLs is high, with no systemic risk factors associated with this complication, suggesting that it may be attributable to the material and/or the manufacturing process. [J Refract Surg. 2024;40(2):e98-e107.].

Frequency of Optic Refractive Changes during Third Trimester of Pregnancy

Objective: To determine the frequency of optical refractive changes (myopia, hypermetropia) during third trimester of pregnancy.&#x0D; Material and method: This cross-sectional study recruited 86 participants who had pregnancy in third trimester of mean age 25 to 40 years of age and who are not diabetic, hypertensive and spectacle users in Eye OPD of Shalamar Hospital, Lahore. Their visual acuity for distance was determined by Snellen chart and Retinoscope. Chi-square was used for the comparison of qualitative variables.&#x0D; Results: VA and refractive errors are the physiological changes during pregnancy, they are mostly transient and resolved after postpartum. The results of this study showed the frequency of myopia was 91.9% and hypermetropia was 8.1%. So, the myopia was the refractive error that is mostly reported during third trimester of pregnancy with symptoms of blurred vision, headache, itching.&#x0D; Conclusion: Pregnancy causes refractive error and progressive reduction in visual acuity for distance and there is slight change in visual acuity for near. Myopia was the commonest refractive error during third trimester of pregnancy. The main symptoms reported during third trimester of pregnancy were blurred vision, itching and headache.

Compensatory Interactions between Corneal and Internal Astigmatism despite Lifestyle Changes.

This study explores whether children's refractive errors and visual behaviors reverted to pre-COVID-19 levels a year after normal schooling resumed in Hong Kong as well as the impact of corneal and internal astigmatism on refractive astigmatism development. Vision survey data and questionnaire results collected in 2022 (n = 119) and 2020 (n = 173) were compared. Cross-sectional data showed similar proportions of astigmatism (cylindrical power ≥ 0.75 D) in the 2020 (49.1%) and 2022 cohorts (55.5%). Despite a 0.28 D increase in corneal astigmatism, a compensatory 0.24 D increase in internal astigmatism of opposite direction kept refractive astigmatism relatively stable. The questionnaire data showed that children spent an additional 0.5 h/day outdoors on weekends post-resumption of normal schooling but engaged in more near-work activities, especially non-screen near-work, by approximately 1 h/day on both weekdays and weekends. These findings were supported by longitudinal data from 72 children who participated in both surveys. This study highlights the significant role of corneal and internal astigmatism in refractive astigmatism changes. Despite the return to in-person classes, children's total near-work time increased and astigmatism remained high. These findings underscore the need for comprehensive strategies to reduce the high environmental risks for refractive error development in children.

Clinical Aspects of Transient Myopia after Blunt Eye Trauma

Purpose: To investigate the clinical aspects of transient myopia after blunt eye trauma.Methods: The medical records of 32 patients treated at our hospital for from 2020 to 2022 traumatic microhyphema were analyzed retrospectively. The visual acuity, intraocular pressure, anterior chamber cells, anterior chamber depth, axial length, lens thickness, and refractive index were analyzed immediately after injury and after treatment. Patients with additional diseases such as vitreous and retinal hemorrhage, traumatic retinal detachment, iridodialysis, or orbital fracture were excluded. Correlations between the myopic changes and the amount of myopic refractive change caused by trauma were analyzed.Results: The 32 patients included 24 (75%) males and 8 (25%) females. The average myopic change was -3.03 ± 0.92 (range -1.00 to -5.25) diopters (D). The average change in anterior chamber depth due to trauma was -0.22 ± 0.11 mm, the change in lens diameter was 0.20 ± 0.09 mm, and the change in axial length was -0.07 ± 0.05 mm. The average change in refractive index due to ciliary spasm was -1.63 ± 0.65 D. The correlations between the change in refractive index and anterior chamber depth (r = 0.475, &lt;i&gt;p&lt;/i&gt; = 0.008), traumatic ciliary spasm (r = 0.649, &lt;i&gt;p&lt;/i&gt; &lt; 0.001), and lens thickness (r = -0.184, &lt;i&gt;p&lt;/i&gt; = 0.330) were determined.Conclusions: Factors such as ciliary spasm, change in the anterior chamber depth, anterior shift of the lens-iris diaphragm, and increased lens thickness affect the myopic changes caused by trauma. Of these, a shallower anterior chamber depth and ciliary spasm are highly correlated with the transient myopic changes.

Refractive Changes After Horizontal Strabismus Surgery

Purpose To investigate the changes in refractive status after surgery in patients with horizontal strabismus and high refractive error. Methods This was a prospective study of patients with horizontal strabismus and high refractive error. The patients were divided into a horizontal rectus recession group (group 1) and a horizontal rectus recession combined with horizontal rectus resection group (group 2). The postoperative follow-up duration was 3 months. The refractive status of the patients was evaluated at each postoperative examination, and the refractive changes in the two groups were compared. Results The spherical equivalent in group 1 changed by –0.26 D at 3 months postoperatively relative to the preoperative value (p = 0.078), indicating gradual progression toward myopia over time, but the difference was not significant; however, the postoperative cylinder in group 1 significantly increased by 0.34 D at 3 months postoperatively relative to the preoperative value (p = 0.03). The spherical equivalent in group 2 also indicated progression toward myopia; compared with the preoperative value, the spherical equivalent significantly decreased by –0.28 D (p = 0.019) at 1 month postoperatively and decreased by –0.21 D at 3 months postoperatively. The regression line drawn among the points also indicated a progression in the spherical equivalent toward myopia. In group 2, the cylinder increased by 0.30 D (p = 0.004) from the preoperative level at 1 month postoperatively, peaked, then decreased by 3 months postoperatively. Conclusions Patients with high refractive error who undergo horizontal strabismus correction will experience myopic shift. Patients who undergo rectus recession surgery should be fully informed of the possibility of changes in astigmatism preoperatively. For patients who undergo horizontal rectus recession combined with horizontal rectus resection, it is not recommended that glasses be changed within 1 month after surgery.

Patterns in refractive error and treatment delay in keratoconus-An Australian study.

Keratoconus is the most common primary corneal ectasia and is associated with significant morbidity. In its early stages, keratoconus is often asymptomatic, making the identification of subclinical disease challenging. Refractive error is a parameter that is documented at most routine optometry visits, yet interestingly, changes in refraction of keratoconic patients over time have not yet been studied and compared with the general population. Early diagnosis of keratoconus facilitates timely referral for treatments such as corneal collagen cross-linking, which has been shown to slow disease progression. In this context, documenting delays between initial presentation to the optometrist and referral for collagen-cross-linking as well as comparing the trends in visual acuity and refractive error between keratoconic and non-keratoconic patients over time are particularly relevant.

The effect of pterygium on front and back corneal astigmatism and aberrations in natural-light and low-light conditions

BackgroundTo investigate the effect of different sizes of pterygium on the front and back corneal topography, refractive changes and aberrations in natural-light and low-light conditions.MethodsSixty subjects with unilateral primary nasal pterygium were enrolled in this study. All the patients’ uncorrected, best spectacle-corrected visual acuity, corneal topographic aberration data in 3 mm and 7 mm areas were collected. The pterygium size was evaluated by the slit-lamp photography and Sirius Scheimpflug Analyzer.ResultsThe front topographic astigmatism values, corneal total aberrations, and higher-order aberrations in 3 mm and 7 mm areas were higher in the pterygium group than those in the control group. The pterygium horizontal length and thickness were moderately to strongly correlated with astigmatism and RMS of aberrations, while pterygium vertical length showed no or just mild correlation with the corneal astigmatism and aberrations. Compared to the readings in 3 mm area, the front and back corneal astigmatism and aberrations were larger in 7 mm area.ConclusionsPterygium led to visual impairment by inducing astigmatism and aberrations. In low-light condition, the visual function worsened due to increased corneal astigmatism values and aberrations.

Validation of a method to assess night myopia in a clinical setting

A study was conducted with 115 subjects who regularly drove at night to validate a refraction protocol for detecting refractive visual changes from daytime to nighttime conditions. Objective and subjective refractions were performed in both photopic and mesopic conditions, with a dark adaptation period before the mesopic subjective refraction. The results showed that in mesopic conditions, visual acuity decreased by 0.2 logMAR units on average (p < 0.01), and there was a myopic refractive shift of − 0.36 ± 0.20 D (p < 0.01). Most subjects (92.2%) exhibited a myopic refractive shift of at least 0.12 D. Compensation of refractive shift improved mesopic visual acuity by 0.06 logMAR on average (p < 0.01) and higher refractive shifts showed higher improvement. Night Rx was preferred by 82.1% of subjects with myopic refractive shift. Gender and age did not significantly affect the refractive shift, although myopes showed a higher shift compared to emmetropes (p < 0.01). The refractive shift remained stable over time when the time slot of the day did not change (p < 0.01). Night Rx protocol proved to be a robust and accurate method for identifying drivers with refractive changes when transitioning from photopic to mesopic conditions. The high prevalence and inter-individual variability of Rx shift highlight the need of customized refraction.

Post-Operative Refractive Changes After Cataract Surgery in Children Less Than 4 Years of Age

Aim: To observe the changes in refraction after Cataract surgery in children less than 4 years of age using Dahans formula. Methods: The retrospective evaluation of the records of children with congenital and developmental cataracts who underwent cataract operations with intraocular lens implantation was conducted. The patients’ ages ranged from 6 months to 4 years. All the sutures of cornea were removed after 1 month of surgery. IOL power was calculated using Dahan’s formula based on axial length. Refraction was performed after 1, 3, 6, and 12 months. Results: About 40 eyes of 20 children with bilateral congenital &amp; developmental cataract (11 males and 9 females) were included. The age range was 6 months to 4 years &amp; mean was 28.8±1.38 months. Significant myopic shift was observed in all the children and maximum myopic shift was observed in children below 2 (0-24 months) years of age. Conclusion: Significant myopic shift has been observed in children. So, under corrected IOL implantation is safe to achieve target refraction.