Amplitude Of Accommodation Research Articles

Short-Term Effects of Various Contact Lenses on Accommodative Function in Myopic Children.

To assess the short-term impact of different types of contact lenses on accommodation in the same group of myopic children compared with single-vision spectacle lenses. Thirty myopic children aged 10.2 ± 1.5 years were enrolled. Each participant was corrected with four different modalities in following sequence: single-vision spectacles (SVSP), single-vision soft contact lens (SVSCL), a high-addition multifocal soft contact lens (MFSCL), and orthokeratology lenses (OKL). Measurements included the dynamic accommodative stimulus-response curve (ASRC), distance accommodative facility (DAF), negative relative accommodation (NRA), and positive relative accommodation (PRA). Repeated-measures analysis of variance with Bonferroni correction was performed. The accommodative parameters differed among the four modalities except for the slope of ASRC (F = 1.700, P = 0.173). Single-vision spectacle lens exhibited the highest accommodative lag area (10.08 ± 1.65 D2) and the lowest objective accommodative amplitude (7.72 ± 0.93 D) and PRA (-2.51 ± 0.62 D) (all P < 0.05). Multifocal soft contact lens, OKL, and SVSCL showed no significant differences in accommodative lag area (8.93 ± 1.78, 7.98 ± 2.33, 8.44 ± 2.20 D2), NRA (2.23 ± 0.33, 2.23 ± 0.38, 2.39 ± 0.33 D), PRA (-3.05 ± 0.78, -3.43 ± 1.05, 3.00 ± 1.02 D), or DAF (23.8 ± 6.99, 26.0 ± 8.23, 23.3 ± 7.07 D); however, OKL (8.68 ± 1.08 D) induced greater objective accommodative amplitude than SVSCL (8.26 ± 0.97 D) (P = 0.010). Single-vision spectacles exhibited worse accommodative function than the other three modalities. However, no significant changes in accommodation were detected when using OKL or high-addition MFSCL compared with SVSCL, except higher objective accommodative amplitude with OKL than SVSCL.

In Vivo Brillouin Analysis of Lens Nucleus and Cortex in Adult Myopic Eyes and Their Correlation With Accommodation.

The purpose of this study was to investigate the in vivo biomechanical properties of crystalline lens nucleus and cortex in adults with myopia, their potential influences, and the correlation between these properties and ocular accommodation. The study included 195 right eyes of 195 participants, divided into 4 groups based on spherical equivalent: emmetropia (37 eyes), low myopia (41 eyes), moderate myopia (59 eyes), and high myopia (58 eyes). Participants underwent comprehensive ophthalmological examinations, including intraocular pressure, axial length, cycloplegic refraction, lens morphology, accommodation measurements, and Brillouin optical scanning of the lens. Additionally, demographic information, such as age and sex, was recorded. Normality tests were performed on the data using the Kolmogorov-Smirnov test. Between-group differences were examined using the Kruskal-Wallis test. Correlation and multiple regression analyses were conducted to analyze the factors associated with lens biomechanical properties and accommodation. The mean longitudinal modulus of the crystalline lens nucleus (LMN), anterior cortex (LMAC), and posterior cortex (LMPC) was 3.395 ± 0.027 GPa, 3.030 ± 0.066 GPa, and 2.990 ± 0.066 GPa, respectively, in adult myopia and 3.342 ± 0.024 GPa, 3.015 ± 0.0488 GPa, and 2.978 ± 0.049 GPa, respectively, in emmetropia. LMN was significantly higher in myopia (difference = 0.047, 95% confidence interval [CI] = 0.037 to 0.057, P < 0.001) and increased significantly with higher degrees of myopia (standardized β = -0.712, P < 0.001). No statistical differences in the LMAC or LMPC were observed between myopia and emmetropia. Lens densitometry on the centerline was the only lens parameter independently correlated with LMN (standardized β = -0.282, P < 0.01). Increased LMN in myopia was independently correlated with increased amplitude of accommodation (AMP) and decreased accommodative facility (AF; standardized β = 0.198, -0.237, all P < 0.05). LMN was significantly higher in adult patients with myopia than in emmetropia and increased with increasing myopia. Increased LMN in myopia significantly correlated with decreased AF and increased AMP. High LMN may be an important biological alteration during the development of adult myopia, especially high myopia, providing new insights into myopia pathogenesis.

Analysis of Accommodation and Optical Quality After Myopia Surgery With Phakic Intraocular Lens Implantation.

To characterize the accommodative function and optical quality in high and moderate myopia after the implantation of a phakic intraocular lens implantable collamer lens (ICL). This was a prospective observational study of 20 myopic patients undergoing bilateral ICL implantation with a mean spherical equivalent (SE) of -7.44 diopters (D) (range: -4.37 to -12.00 D). Amplitude of accommodation, subjective accommodative response, optical quality parameters including modulation transfer function cut-off, Objective Scatter Index, and Strehl ratio, and objective accommodative response with a double-pass system (HD Analyzer; Visiometrics SL) were assessed before surgery and 1 month postoperatively. Mean residual refractive error improved to 0.20 ± 0.19 D (P < .001) at 1 month postoperatively compared to preoperatively. Amplitude of accommodation decreased significantly by 1.65 D (P < .001) from 7.65 ± 1.33 D at baseline to 6.00 ± 0.95 D at 1 month after ICL implantation. However, no significant changes were found in accommodative response or in the optical quality parameters of modulation transfer function cut-off, Objective Scatter Index, Strehl ratio, and objective accommodative response with HD Analyzer between preoperatively and 1-month postoperative follow-up (P > .05). ICL implantation in healthy patients with moderate to high myopia does not significantly alter accommodative function, as measured by subjective or objective methods, or optical quality parameters, except for a non-clinically relevant decrease in amplitude of accommodation. [J Refract Surg. 2025;41(4):e325-e332.].

Accommodative and binocular characteristics in myopes with age-related accommodation deficiency

BackgroundTo investigate accommodative and binocular characteristics in myopic patients with age-related accommodation deficiency, and to investigate the relationship of accommodation amplitude (AA) with other accommodative and binocular parameters.MethodsMyopic patients between 40 and 50 years old to undergo refractive surgery were enrolled. Accommodative function, including AA, positive and negative relative accommodation (PRA and NRA), accommodative response (binocular cross cylinder, BCC), and binocular accommodative facility (BAF) were examined. Binocular vision measurements including simultaneous perception, fusional vergence, and stereovision assessed with a synoptophore. Near point of convergence (NPC) and the gradient accommodative convergence/accommodation (AC/A) ratio were also measured. A questionnaire was used to assess subjective visual discomfort experienced after prolonged near work.ResultsA total of 145 subjects were evaluated, with a mean age of 42.59 ± 2.89 (SD) years. In the full data set, 96(66.21%) of patients had PRA (>-1.50 D), 21(14.48%) of patients had NRA (< 1.50 D), and 113(77.93%) of patients had BCC (< 0.25 D). Out of 97 patients, 17(17.53%) had AC/A (< 2), 54(55.67%) had NPC (> 7.5 cm), 51(52.58%) had BAF (< 5 cpm). As for the simultaneous perception, 59(60.82%) had values greater than 0 prism dioptres. Adjusting for associated factors, participants with lower AA were more likely to be older (odds ratio [OR], 2.080; 95% confidence interval [CI], 1.523–2.841) and with milder myopia (OR, 1.280; 95% CI, 1.029–1.594). Lower BAF (OR, 4.990; 95% CI, 1.731–14.386) was more likely to be found in individuals with lower AA. The three most commonly reported visual discomforts were eye strain or soreness, ocular pain or headache, and blurred text.ConclusionFor myopes at the early stage of presbyopia, the continuous tension in the vergence system was also worthy of our attention, in addition to the well-known AA insufficiency. Comprehensive assessment of the binocular status and appropriate management is recommended before and after corneal refractive surgery.

Anterior Segment Characteristics and Quality of Life of Patients with Central Serous Chorioretinopathy.

Background: This study aimed to compare the anterior segment characteristics of patients with central serous chorioretinopathy (CSCR) to those with diabetic retinopathy (DR) and healthy controls. Additionally, it explored the possible associations between quality of life and anxiety with CSCR. Methods: A single-center, cross-sectional study involving patients aged 23-61 years diagnosed with CSCR or DR, and healthy patients. Comprehensive ophthalmic examinations included best-corrected visual acuity (BCVA, LogMAR), objective and subjective refraction, and anterior and posterior segments optical coherence tomography (OCT) imaging. Participants completed the Quality-of-Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q) and the Beck Anxiety Inventory (BAI). Statistical analysis included Kruskal-Wallis, Tukey post-hoc, Chi-square, and Spearman correlation tests to compare the three groups. Results: A total of 53 patients were recruited (16 CSCR, 8 DR, 29 controls; 52.8% males), with an additional 16 CSCR patients completed only the questionnaires. CSCR and DR patients were the same age as the controls (43.8 ± 9.0, 42.7 ± 9.9, 37.06 ± 13.61 years, respectively, p = 0.19). CSCR and DR patients had similar BCVA, lower than controls (0.19 ± 0.30, 0.15 ± 0.13, 0.01 ± 0.02 LogMAR, respectively, p < 0.01). CSCR patients exhibited more hyperopic refraction compared to healthy controls (p < 0.01) and reported significantly lower life enjoyment and satisfaction than DR and healthy individuals (51.56 ± 9.17, 53.75 ± 7.81, 60.03 ± 7.32, respectively, p < 0.01). No significant correlations were found between anxiety levels and pupil size, anterior chamber depth (ACD), amplitude of accommodation (AA), and intraocular pressure (IOP) among study groups (p > 0.05). Conclusions: CSCR patients demonstrated lower life enjoyment and satisfaction, reduced BCVA, and hyperopic refraction compared to healthy patients. They also tended to have higher stress and anxiety levels. Both CSCR and DR patients shared similar anterior segment characteristics.

Subjective and objective measurements of the amplitude of accommodation: Revisiting the existing methods and clinical evaluation of newer techniques.

To evaluate the repeatability and agreement of established and newer methods for measuring the amplitude of accommodation in non-presbyopic and early presbyopic individuals. The amplitude of accommodation of 81 participants was measured using five different methods (two push-up techniques, two minus lens techniques and one objective technique) with different measurement principles. Among these, two new techniques were introduced: an electronic push-up and a minus lens technique with a tunable lens. Three repeated measurements were performed with each method. The repeatability limit and non-parametric Bland-Altman analysis were used to describe the repeatability and agreement of each method. The repeatability limit was between ±0.7 D and ±1.4 D for the minus lens techniques, around ±1.8 D for the push-up methods and ±1.4 D for the objective procedure. The largest differences in median values were found between the push-up and objective methods. Push-up methods are most likely to overestimate accommodation, while the objective method gives the lowest results. New techniques show good repeatability for measuring the amplitude of accommodation. Among the subjective methods, the minus lens technique with the tunable lens gives the best repeatability, is one of the fastest and gives results most similar to the objective method.

Visual quality following FS-LASIK with Q-value-guided optimized monovision in patients with myopia and presbyopia: Custom-Q in treating myopia and presbyopia

Visual quality following FS-LASIK with Q-value-guided optimized monovision in patients with myopia and presbyopia: Custom-Q in treating myopia and presbyopia

Effects of Orthokeratology in Patients With Convergence Insufficiency Exophoria and Myopia.

To observe and analyze the effects of orthokeratology in patients with convergence insufficiency, exophoria, and myopia. Thirty patients (60 eyes) between 8 and 15 years old with myopia and convergence insufficiency exophoria treated with orthokeratology at the First Affiliated Hospital of the Baotou Medical College from December 2022 to December 2023 were prospectively enrolled. General information was gathered and examinations were performed at baseline and at 2 weeks and 1, 3, and 6 months after switching to orthokeratology lenses. Examinations included assessments of distance/near visual acuity, near point of convergence, distance and near horizontal phoria, near positive fusional vergence, and monocular amplitude of accommodation. The median age of the participants was 10 years (range: 8 to 15 years), and 40% were female. The baseline refractive error was -2.00 diopters (D) (range: -4.00 and -1.00 D). After 6 months of treatment, we found statistically significant differences in near point of convergence (95% confidence interval: -13.99 to -8.67), positive fusional vergence (95% confidence interval: 15.32 to 11.42), and monocular amplitude of accommodation (95% confidence interval: 6.62 to 4.51) compared with baseline. In addition, the mean pretreatment near horizontal phoria decreased from 6.83 ± 1.44 to -4.90 ± 1.29 prism diopters after the 6 months of treatment (95% confidence interval: -2.92 to -0.94). This study showed that the use of orthokeratology lenses with an increased compression factor of 1.75 D may improve near point of convergence, positive fusional vergence, and monocular amplitude of accommodation for the treatment of convergence insufficiency with myopia. [J Pediatr Ophthalmol Strabismus. 20XX;X(X):XXX-XXX.].

Presbyopia and associated factors specific to age groups

ABSTRACT Clinical relevance Presbyopia rapidly progresses between 40 and 55 years of age and the amplitude of accommodation is lost around 55 years of age; however, the factors associated with presbyopia by age group in relation to ocular surface and retinal thickness have not been determined. Background Age and other factors are associated with presbyopia, however, factors specific to age groups have not been described. Methods Near add power was compared among 3000 healthy individuals grouped by age; 40s (aged 40–49 years), 50s (aged 50–59 years), and 60s (aged 60–69 years). Regression analysis and comparison of odds ratios for risk factors of presbyopia determined by near add power were conducted. Results The mean near add power was 1.21 ± 0.66 D in 40s, 2.16 ± 0.59 D in 50s, and 2.72 ± 0.44 D in 60s. Regression analysis of near add power and ocular parameters indicated age, astigmatic errors, intra-ocular pressure, mean deviation, thickness of ganglion cell complex (GCC) and peripapillary retinal nerve fibre layer (RNFL) were associated with near add power in 40s, whilst age, tear break-up time, and peripapillary RNFL were associated with near add power in 60s. Comparison of odds ratios for risk factors for reaching mean near add power in each age group revealed that age, astigmatic errors, mean deviation (40s only), and GCC and RNFL thickness were significant in 40s and 50s, whilst tear break-up time and RNFL thickness were significant in 60s. Conclusions Age and numerous other factors were significantly associated with near add power in 40s and 50s, while fewer factors were significant in 60s, suggesting age-specific management for presbyopia may be recommended.

COMPARISON OF PLUS LENS ADDITION VERSUS VISION THERAPY FOR THE MANAGEMENT OF ACCOMODATION INFACILITY

Background: Accommodation is the process by which the eye adjusts its lens to maintain a clear focus on objects at varying distances, primarily controlled by the ciliary muscle. Accommodative dysfunction, particularly accommodative infacility, impairs this ability, leading to symptoms such as blurred vision, eye strain, headaches, and difficulty with reading and other near-vision tasks. Managing this condition is crucial for improving visual comfort and function. Plus lens addition and vision therapy are two widely used treatment approaches, yet their comparative effectiveness remains unclear. Objective: This study aimed to evaluate and compare the effectiveness of plus lens addition versus vision therapy in managing accommodative infacility. Methods: A randomized controlled trial was conducted at the Ophthalmology Eye Outpatient Department of Al Rehman Hospital and Dar ul Shifa Eye Hospital, Lahore, over six months following ethical approval. A total of 38 participants, aged 15 to 35 years, with newly diagnosed accommodative infacility, were randomly assigned into two equal groups: plus lens addition (n = 19) and vision therapy (n = 19). Comprehensive baseline assessments included visual acuity, near point of accommodation (NPA), near point of convergence (NPC), amplitude of accommodation (AA), negative relative accommodation (NRA), positive relative accommodation (PRA), monocular fixation (MF), and binocular fixation (BF). Each treatment was administered for six weeks, followed by post-treatment evaluations using the same standardized instruments. Data were analyzed using SPSS Version 27, employing descriptive statistics, the Wilcoxon signed-rank test, and ANOVA. Results: Post-treatment, the vision therapy group exhibited significantly greater improvement in NPA (7.8 ± X vs. 10.5 ± X, p &lt; 0.001), AA (10.1 ± X vs. 8.9 ± X, p &lt; 0.001), PRA (-3.0 ± X vs. -2.7 ± X, p = 0.002), and NPC (6.862 ± 0.70 vs. 14.09 ± 1.24, p &lt; 0.05) compared to the plus lens group. Both groups showed statistically significant enhancements in all visual function parameters (p &lt; 0.05). Conclusion: While both plus lens addition and vision therapy were effective in improving accommodative function, vision therapy demonstrated superior outcomes in enhancing accommodation flexibility, convergence, and binocular stability. These findings support the recommendation of vision therapy as a preferred intervention for long-term improvement in accommodative infacility.

Prevalence of Accommodative Insufficiency in Children With Normal Accommodative-Convergence/Accommodation Ratio and Its Association With Refractive Error: A Cross-Sectional Study.

With the increasing use of digital devices among the pediatric population, asthenopia has become increasingly common. While refractive errors are the most prevalent cause, they can sometimes be linked to undiagnosed or underdiagnosed binocular vision disorders, such as accommodative insufficiency (AI). In many cases, simple refractive correction alone does not alleviate asthenopia. This study aims to determine the prevalence of AI in children with a normal accommodative-convergence/accommodation (AC/A) ratio and to investigate the correlation between accommodative amplitude and refractive errors. The cross-sectional study was conducted from April 2024 to December 2024 to assess the prevalence of AI in children aged between six and 18 years with normal AC/A ratios. The study was approved by theEthics Committee of Kalinga Institute of Medical Sciences, Bhubaneswar, India. The minimum required sample was 384, assuming a 50% prevalence, and was increased to 500 participants to account for a 20% non-response rate. Uncorrected distance visual acuity (UCVA) was assessed using a Snellen chart. Refraction included objective retinoscopy, subjective refraction, and cycloplegic refraction using 1% cyclopentolate. Binocular vision was evaluated using the Hirschberg test, ocular motility assessment, slit-lamp biomicroscopy, intraocular pressure measurement, ophthalmoscopy, and heterophoria testing. The AC/A ratio was calculated following the calculated method. Amplitude of accommodation (AA) was measured using the push-up method with a Royal Air Force (RAF) ruler. Hofstetter's formula, 15 - (Age/4), was used to determine the minimum expected AA. Participants with AA at least 2.00 D below this threshold were diagnosed with accommodative insufficiency. Participants were categorized into groups of six to 11 years and 12 to 18 years to account for age-related variations in accommodation. Statistical analysis included the chi-square test for categorical comparisons and Spearman'scorrelation for assessing relationships between AA and refractive error. Out of the 500 participants, 238 were male and 262 were female, ranging in the age range of six to 18 years, with a mean age of 12.78 ± 3.12 years. It was discovered that 162 individuals (32.4%) lacked adequate accommodations. The mean AA for our study participants was 11.09 ± 2.60 years. The prevalence of AI was 32.4% overall, with 32.6% (95% confidence interval: 27.1-38.4) in females and 32.2% (95% confidence interval: 26.5-38.3) in male patients. We found no discernible relationship between the AA and refractive error in our study. In this study, with an overall AI prevalence of 32.4%, the ability to maintain comfortable, clear, and effective vision is notably affected by accommodative dysfunction alone, even when AI and convergence insufficiency (CI) coexist. Our investigation found no correlation between refractive error and the AA.

Longitidunal changes in accommodation amplitude after strabismus surgery.

Longitidunal changes in accommodation amplitude after strabismus surgery.

Accommodative functions in opium users and non-users

Background: Emerging evidence highlights a concerning prevalence of accommodative and convergence anomalies in individuals with opioid use disorder. However, there remains a significant scarcity of data comparing accommodative functions of opium users and non-users. Hence, we investigated potential changes in accommodative functions of opium users compared to that of non-users. Furthermore, we evaluated changes in these parameters after administering 5% phenylephrine eye drops, both within and between the two groups. Methods: This cross-sectional case-control study recruited opium users and non-users. The binocular amplitude of accommodation (AA), monocular estimate method (MEM), negative and positive relative accommodation (NRA and PRA, respectively), and monocular and binocular accommodative facility (AF) were assessed and documented. All measurements were repeated 30 min after instillation of one drop of 5% phenylephrine hydrochloride eye drops. Results: We recruited 103 opium users and 107 non-users, with comparable mean ages (P &gt; 0.05) but significantly different sex ratios (P &lt; 0.05), with men outnumbering women among the opium users. All accommodative functions measured before and after the instillation of 5% phenylephrine, along with the differences in their values between the two time points, were comparable between the two groups (all P &gt; 0.05), with the exception of the right-eye AF, which was significantly higher in non-users than in opium users after instillation (P &lt; 0.05). Within the opium user group, all accommodative functions exhibited significant differences between pre- and post-instillation measurements (all P &lt; 0.05), except for NRA, which did not change (P &gt; 0.05). In contrast, the non-user group showed no significant differences between pre- and post-instillation measurements for all accommodative functions (all P &gt; 0.05), except in the AA and the right-eye MEM (both P &lt; 0.05). Conclusions: We observed small but significant changes in most baseline accommodative functions after the application of 5% phenylephrine eye drops in opium users. In contrast, most parameters remained unchanged in healthy non-users. When comparing the results between the two groups pre- and post-application of phenylephrine, we found similar accommodative functions overall. However, non-users had a significantly higher value for the right-eye AF following the instillation. To better understand potential binocular anomalies in opium users, further longitudinal studies that are matched for age and sex should be conducted, focusing on additional aspects of binocular vision and ocular motility.

Evaluation of Accommodation Amplitude and Convergence Insufficiency in Patients with Multiple Sclerosis

ABSTRACT Purpose To evaluate the near reflex components, including accommodation, convergence, and binocular fusional vergences in patients with multiple sclerosis (MS). Material-Method MS patients under 35 years of age without visual evoked potential (VEP) abnormalities (MS Group) and age-matched healthy individuals of (Control Group) were included in the study. Fusional vergence amplitudes, the amplitude of accommodation (AA), stereopsis measurements, near-object fixation and near point of convergence (NPC) measurements, Convergence Insufficiency Symptoms Survey (CISS) results, and the presence of nystagmus were recorded retrospectively from the files of the cases. Statistical comparison was made between the groups. Results The mean age was 28.04 ± 3.7 years in the MS group (20 females, 4 males) and 27.16 ± 3.1 years in the control group (20 females, 5 males) (p = .763). There was no statistically significant difference between groups in stereopsis (p = .395), mean convergence (p = .666), and divergence amplitudes (p = .773) at a distance, and mean convergence and (p = .836) divergence amplitudes (p = .877) at near, and NPC measurements (p = .908). The mean AA was 5.31 ± 0.7 D in the MS group and 6.1 ± 0.8 D in the control group (p < .001). CISS results were lower in the control group (p < .001). In addition, gaze-evoked nystagmus was statistically significantly higher in the MS group (p < .001). Conclusion Compared to the healthy control group, MS patients under 35 who did not have optic neuritis had lower accommodation amplitude and more signs in favor of convergence insufficiency symptoms. In addition, gaze evoked nystagmus was observed at a higher rate in the MS group. These findings may guide us in understanding the asthenopia findings of MS patients without optic neuritis.

Evaluation of Auricular Acupressure on Myopia Prevention among Children Aged 6–12 Years with Pre-Myopia in China: Study Protocol of a Prospective Multi-Center Randomized Controlled Trial

Background: The increasing prevalence of myopia among Chinese children and adolescents, especially at younger ages, has emerged as a significant concern in recent years. Pre-myopia is a key period for myopia prevention and control in children and adolescents. Previous studies suggested auricular acupressure (AA) therapy might offer a viable approach to prevent and slow down myopia progression. Nonetheless, these studies lack robust, high-quality, large-scale, multi-center evidence to conclusively support such assertions. The purpose of this research is to evaluate the efficacy, safety, and economic benefits of AA therapy in preventing myopia in Chinese children aged 6–12 years with pre-myopia. Methods: The single-blind, multi-center, parallel-group, randomized controlled trial will involve 318 pre-myopic children from 20 different centers across China. After recruitment, these participants will be randomly assigned to two groups (the AA group and the control group) at a 1:1 ratio. The AA group will receive auricular point sticking therapy along with health education for a period of 24 weeks, while the control group will be provided the sham AA treatment and routine health education. The assessments of outcomes will be conducted at the start of this study, and then after 4, 8, 12, and 24 weeks. The primary outcome is the change in spherical equivalent refraction at various follow-up times. The secondary outcomes include the number of myopia cases, uncorrected visual acuity, axial length, corneal curvature radius, accommodation amplitude, retinal and choroidal thickness, and eye behavior management. In addition, the cost-effectiveness analysis will be used as the evaluation index for economic assessment. Discussion: The results of this research will provide evidence on the efficacy, safety, and economic benefits of AA therapy in preventing myopia among children aged 6–12 years with pre-myopia in China.

Effectiveness of Corneal Reshaping Lenses in Controlling Axial Length in Myopic Children and Adolescents

Objective: To explore the effect of keratoplasty on the control of the ocular axis in children and adolescents with myopia. Methods: Seventy-five cases of children and adolescents who underwent myopia correction at a hospital between September 2023 and August 2024 were selected. Participants were divided into a control group (37 cases, wearing eyeglasses) and an observation group (38 cases, wearing keratoplasty lenses) using the random number method. Visual function, naked-eye visual acuity, ocular axis length, and refractive error were compared and analyzed between the two groups before and one year after the correction treatment. Results: Before correction, there were no statistically significant differences in the amplitude and sensitivity of accommodation between the two groups (P &gt; 0.05). After correction, all indices increased significantly in both groups, with the observation group showing higher values than the control group (P &lt; 0.05). Similarly, prior to correction, there were no significant differences in naked-eye visual acuity, axial length, or refractive error between the two groups (P &gt; 0.05). After correction, all indices improved significantly in both groups; however, the observation group demonstrated superior results compared to the control group, with statistically significant differences (P &lt; 0.05). Specifically, the naked-eye visual acuity in the observation group was higher, refractive error was lower, and ocular axis length was shorter than in the control group, all with statistical significance (P &lt; 0.05). Conclusion: Keratoplasty effectively controls the ocular axis in children and adolescents with myopia. It not only enhances visual function but also significantly improves naked-eye visual acuity, reduces refractive error, and shortens the length of the ocular axis.

Efficacy of varying target size and varying distance on the amplitude of accommodation by using Donder’s and Sheard’s method

Abstract PURPOSE: To compare the measurement of amplitude of accommodation (AOA) by various techniques and to assess the effect of varying target size and varying distance on the AOA using Donder’s and Sheard’s Method. METHODS: A prospective study was conducted among 100 students aged between 18 and 30 years who met the inclusion criteria. Subjects with best-corrected visual acuity 6/6 at near and distance were included in the study. A comprehensive eye examination of the patients was carried out. Then, assessment of the near point of accommodation with the Royal Air Force rule by giving targets of different font sizes (N8 and N10) was performed repeatedly over distance correction, and diopter reading was noted. Then minus lens technique at different distances (at 33 cm and at 40 cm) was used to assess the AOA. IBM-SPSS 22.0 was used for data analysis. RESULTS: t of a total of 100 participants, 49 (49%) were males and 51 (51%) were females, with a mean age of 20 ± 1.79 years. Donder’s method showed the highest AOA compared to Sheard’s method. It has been found that there was a clinically significant difference in the AOA with the two different letter sizes (N8 and N10) during the monocular measurement using Donder’s method. Furthermore, a clinically significant difference was found between the AOA when measured monocularly as well as binocularly at two different distances (at 33 cm and 40 cm) using Sheard’s method. CONCLUSION: We have concluded that the highest AOA was measured using Donder’s method, and the effect of varying letter size and varying target distance on AOA using Donder’s and Sheard’s method is clinically significant. It is very crucial to consider the standard target size and target distance during the measurement of AOA as varying target size and target distance could result in varying AOA which may lead to inappropriate diagnosis and management of the condition as well.

Accommodation amplitude change after cosmetic use of the botulinum toxin in the upper face

Purpose Cosmetic botulinum toxin A (BoNT-A) injections are increasing worldwide. Adverse effects need to be evaluated in more detail for BoNT-A regulations. This study aims to assess the anticholinergic effect of BoNT-A on accommodation amplitude (AA) after upper face application. Methods Twenty patients aged between 20 and 45 years were recruited in this prospective, interventional study. Abobotulinum toxin A of 500 units was diluted with 3 ml saline and injected into the forehead, glabellar and periorbital area. AA was measured with both the push-up and minus-lens techniques before and after two weeks of the injections. T-test for normally distributed variables was applied for the comparison of the results. Results The study group comprised 18 women and 2 men with a mean age of 33.9 ± 8.59. AA decreased significantly after two weeks of the injection. In the push-up test, AA was 9.18 ± 4.72 D before BoNT-A injection and decreased to 7.11 ± 3.02 D after the injection (p < 0.001). In the minus lens test, AA reduced from 5.86 ± 2.24 D to 5.24 ± 2.06 D after BoNT-A injection (p < 0.001). Refraction did not change in any of the participants. Conclusion The present study showed that cosmetic upper face BoNT-A injections reduced AA. However, this reduction did not result in any significant symptomatic effects in the patients. These findings suggest that while BoNT-A injection has a measurable impact on the ciliary muscle or its parasympathetic innervation, it may not lead to noticeable clinical outcomes.

Finite element analysis of the lens profile during accommodation.

The magnitude of zonular forces required to change the shape of the human lens while focusing at near; i.e., accommodating, is still under investigation. During accommodation, ciliary muscle contraction induces a large increase in lens central optical power (COP). Here we used finite element (FE) analysis to evaluate the correlation between zonular forces and lens surface curvatures, central thickness, COP, overall lens shape and longitudinal spherical aberration (LSA). Fresh isolated lenses from donors aged 20, 24, 26, and 30 years were the basis for the analyses. Lens nucleus elastic moduli were specified as equal to, 2, 3, 10, 20 and 30 times greater than its cortex. When equatorial zonular (Ez) force was increased in 3.125 x 10-6 N steps while the anterior zonular (Az) and posterior zonular (Pz) forces were decreased in 3.125 x 10-6 N steps, COP was evaluated. Independent of the increase in lens nuclear modulus, less than 0.02 N of Ez force was required to increase COP 10 diopters while Az and Pz forces were decreased. The lens peripheral surfaces flattened, central surfaces steepened, central lens thickness increased, COP increased and LSA shifted in the negative direction consistent with published in vivo accommodation studies. The minimal Ez force required to obtain 10 diopters of COP increase supports that increasing Ez force with decreasing Az and Pz force is the basis for the change in lens shape during accommodation. Since the COP increase was independent of increasing elastic modulus of the nucleus, stiffening of the lens nucleus is not the etiology of the universal age-related decline in accommodative amplitude that results in presbyopia in the fifth decade of life. Increased Ez zonular tension during accommodation has implications for the development and potential treatments of myopia, glaucoma, presbyopia, cortical cataracts and accommodative intraocular lens design.

Visual Status, Ocular Profiles and Associated Quality of Life of Workers in the Weaving Community of Salem District, Tamil Nadu, South India.

To evaluate the visual status, ocular profiles, and associated quality of life (QoL) among workers in the weaving community of Salem District, Tamil Nadu, South India. This study was conducted in rural weaving and textile factories within Salem District, South India, focusing on weaving-related work. From an estimated population of 8,010 employees, 1,230 participants were selected for the study. Three suitable factories were chosen after obtaining appropriate permissions. The inclusion criteria were workers aged 18-60 years actively involved in production roles, while administrative staff were excluded. Visual acuity, was assessed, and refractive errors, including myopia, hypermetropia, and astigmatism, were measured. Visual impairment was defined as a visual acuity of less than 6/12 in either eye. For participants under 40 years of age, additional evaluations included near point of accommodation and near point of convergence. Comprehensive data collection involved recording demographic information, conducting detained eye examination, and assessing quality of life using the low vision quality of life questionnaire (LVQOL). The study included 1,230 participants, with a mean age of 39.46 ± 10.84 years, of whom 74.4% were male. Visual impairment (VI) was observed in 35.04% of participants, with the majority (83.75%) of Vi cases had uncorrected refractive errors (URE) and 7.19% had cataracts. Visual impairment was more prevalent in the 51-60 age group, affecting 48.1% of individuals in this category. Females demonstrated higher odds of spectacle usage compared to males (OR 0.729, 95% CI 0.548-0.969), especially among workers in sewing and presser roles. A low mean near point of convergence (NPC) of 8.84 ± 3.29 cm was noted, with 36% of participants exhibiting reduced amplitudes of accommodation. Color vision defects were identified in 6.0% of females and 4.6% of males. A significant associations was found between occupation, gender, and spectacle usage (X2, N = 122, P = 0.029). Quality of life, as measured by the LVQOL, ranged from 1.8 to 5.0, with a mean score of 4.386 ± 0.6445. A statistically significant correlation was identified between presenting visual acuity and LVQOL scores, indicating that participants with visual impairment had lower overall LVQOL scores (Spearman correlation, P < 0.01). Uncorrected refractive error (URE) emerged out as the primary cause of visual impairment among workers in the weaving industry. Additionally, presenting visual acuity significantly influenced the quality of life (QoL) of participants. These findings underscore the urgent need for timely interventions to enhance both worker performance and overall QoL within the weaving industry.