Refractive Error Values Research Articles

Does blepharospasm effect biometric parameters and intraocular lens power calculations?

To investigate the effect of botulinum toxin-A (BTX-A) treatment on corneal topography, ocular biometry and keratometry in patients with benign essential blepharospasm (BEB) and hemifacial spasm (HFS). This study comprised 66 eyes of 33 patients with BEB and 5 eyes of 5 patients with HFS who underwent BTX-A injections consecutively. Refractive error values, tear break-up time (TBUT), corneal topography [corneal power of flat axis (K1) and steep axis (K2), mean corneal power (Km), corneal astigmatism (K2-K1)] and ocular optical biometry [axial length (AL), anterior chamber depth (ACD)] were recorded before BTX-A treatment and 1 month after BTX-A treatment. The researchers calculated the expected emmetropic intraocular lens power (emm-IOL) using the SRK-T, Holladay, Hoffer-Q and Haigis formulas at each examination. K1 (43.48 ± 2.02 vs. 43.57 ± 2.08, p = 0.036), Km (43.91 ± 1.99 vs. 43.99 ± 2.06, p = 0.024) and ACD (3.22 (2.77-3.76) vs. 3.41 (2.99-4.02), p < 0.001) values were found to be significantly higher. The expected emm-IOL according to the SRK-T (21.04 ± 1.6 vs. 20.93 ± 1.6, p = 0.048), Holladay (21.05 ± 1.6 vs. 20.91 ± 1.62, p = 0.037) and Hoffer-Q (21.08 ± 1.65 vs. 20.94 ± 1.68, p = 0.038) decreased significantly. The expected emm-IOL according to the Haigis formula slightly decreased, but it was not significant (p = 0.386). Additionally, TBUT was found to be significantly lower (p < 0.001) after BTX-A injection. Other parameters were not statistically significant (p > 0.05). Our study is the first in the literature to compare optic biometry data and intraocular lens power calculation formulas before and after BTX-A injection in eyes with BEB and HFS. BTX-A injection could play an important role in changing the keratometric and ACD values. It should be considered that IOL power calculations that might be unpredictable due to blepharospasm, so repeated measurements and especially measurements after releasing the spasm with BTX-A injections, are necessary in BEB and HFS.

Comparison of the PlusoptiX A16 and vision screener V100.

This study compares a novel photoscreening device with a previously validated one in a school-age population. It highlights a tendency of the new device to underestimate myopic spherical equivalent and overestimate hyperopic cases. To compare the PlusoptiX A16 and Vision Screener V100 photoscreeners in a study population of school-age children. One hundred and thirty-three children, with a mean age of 6.4 ± 0.5 years, were evaluated using both the PlusoptiX A16 and Vision Screener V100 photoscreeners. The measurements were taken in random order in a room with diminished ambient lighting. The mean refractive error values for the M component were 0.27 ± 0.67D (PlusoptiX A16) and 0.21 ± 0.58D (Vision Screener V100). For the J0 component, means were 0.16 ± 0.38D (PlusoptiX A16) and 0.06 ± 0.33D (Vision Screener V100) and for theJ45 component the means were 0.03 ± 0.17D (PlusoptiX A16) and 0.06 ± 0.22D (Vision Screener V100). When compared both instruments, statistically significant differences were observed for the M (p=0.017) and J0 (p=0.004) components. The agreement rates between PlusoptiX A16 and Vision Screener V100 across different refractive components were 80.5% for sphere, 82.0% for cylinder, and 40.6% for axis when considering a range of ±0.75 D for sphere and cylinder and ±25.0 degrees for cylinder axis. Simultaneously considering all three conditions, the overall agreement was 73.7%. The Vision Screener V100, while generally aligning well with PlusoptiX A16, tends to underestimate myopic spherical equivalent, overestimate hyperopic cases, and underestimate J0 astigmatism.

Refractive errors in infants with retinopathy of prematurity treated using laser or anti-vascular endothelial growth factor monotherapy

Background: Infants treated for retinopathy of prematurity (ROP) could develop visually significant refractive errors. In this study, we report pre-treatment refractive errors in premature infants with treatment-requiring ROP treated using laser or anti-VEGF monotherapy and compare the components of post-treatment refractive error values between the two treatment groups at different follow-up timepoints.&#x0D; Methods: In this retrospective cohort study, we analyzed 360 eyes of 181 premature infants with treatment-requiring ROP who were referred to Farabi Eye Hospital, Tehran, Iran between March 2020 and April 2021. Of the 360 eyes, 195 received laser monotherapy (laser treatment group) and 165 received an intravitreal anti-VEGF injection (anti-VEGF therapy group). All included eyes underwent pre- and post-treatment cycloplegic refraction. Cycloplegia was induced for each infant by instilling a mixed eye drop containing 1% tropicamide, 2.5% phenylephrine, and 0.5% tetracaine (in equal volumes) in each eye three times at five-minute intervals. Cycloplegic refraction was performed 30 minutes after the third instillation.&#x0D; Results: The mean (standard deviation [SD]) gestational age (GA) and birth weight (BW) of the infants were 29.0 (2.0) weeks and 1241.0 (403.0) g, respectively. The male-to-female ratio in the entire study cohort was 107 (59.1%) / 74 (40.9%), whereas the ratios in the anti-VEGF therapy group and laser treatment group were 47 (56.6%) / 36 (43.4%) and 60 (61.2%) / 38 (38.8%), respectively. The pre-treatment assessment revealed that 218 (60.6%) eyes were hyperopic, 112 (31.1%) were myopic, and 30 (8.3%) were emmetropic. In the anti-VEGF therapy group, 87 (52.7%) eyes were hyperopic, 63 (38.2%) were myopic, and 15 (9.1%) were emmetropic. In the laser treatment group, 131 (67.2%) eyes were hyperopic, 49 (25.1%) were myopic, and 15 (7.7%) were emmetropic. The mean (SD) spherical refractive error and spherical equivalent of refractive error (SEQ) at the 1-week, 1-month, and &gt; 6-month post-treatment follow-up timepoints; the mean cylindrical refractive error at the 3-month post-treatment timepoint; and the mean SEQ at the time of ROP regression were significantly different between the treatment groups (all P &lt; 0.05). The rate of anisometropia increased significantly from 3.4% at baseline to 9.2% at the 6-month post-treatment follow-up timepoint (P &lt; 0.05).&#x0D; Conclusions: In this study, the most common pre-treatment refractive status of all included eyes with treatment-requiring ROP and eyes in each treatment group was hyperopia, followed by myopia and emmetropia. At the more than 6-month post-treatment follow-up, cycloplegic refraction revealed that the laser-treated eyes were significantly more hyperopic than the anti-VEGF-treated eyes, a finding similar to the pre-treatment refraction results. Further studies of same cohort with a longer follow-up period and a control group are needed to determine the real-world effect of each treatment modality on the refractive statuses of children treated for ROP.

Effect of Keratoconus Stage and Classification Parameters on Deep Anterior Lamellar Keratoplasty Outcomes.

The aim of this study was to investigate the effect of the keratoconus (KC) stage according to the Amsler-Krumeich classification system and the parameters used in this classification on deep anterior lamellar keratoplasty outcomes. The preoperative KC stage was determined, and the presence of corneal scarring was noted. The preoperative and postoperative best-corrected visual acuity (BCVA), refractive error, mean central keratometry (K mean ) readings, topographic astigmatism, and minimum corneal thickness (CT) values were recorded. Intraoperative and postoperative complications were also noted. One hundred thirty-seven eyes (54 eyes in stage 3-83 eyes in stage 4) were included in the study. The mean follow-up period was 42.20 ± 24.36 months. There was no statistically significant difference between stage 3 and 4 KC groups for postoperative BCVA, K mean , CT, spherical equivalent, and topographic astigmatism values (each P value >0.05). The effect of preoperative BCVA, K mean , CT, and refractive error values on postoperative BCVA could not be demonstrated ( P = 0.264). In addition, no statistically significant correlation was found between postoperative and preoperative values (each P value > 0.05). Although intraoperative Descemet membrane perforation and postoperative early suture loosening were observed more frequently in stage 4 KC than in stage 3 KC, the 2 groups were statistically similar for these and other complications (each P value >0.05). The preoperative KC stage and the parameters used in classification are not useful in predicting postoperative deep anterior lamellar keratoplasty outcomes. The timing of the surgery should be planned with the awareness that the progression of the disease will not have a negative effect on outcomes.

Comparison of Deep Anterior Lamellar Keratoplasty and Penetrating Keratoplasty in Keratoconic Eyes With Previous Hydrops-Related Corneal Scar.

This study aimed to compare the outcomes of deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) procedures in keratoconic eyes with a previous hydrops-related corneal scar. In this retrospective study, the medical records of patients who had hydrops-related corneal scarring and underwent keratoplasty surgery were reviewed. Patients treated with DALK were classified as group 1, and patients treated with PK as group 2. Preoperative and postoperative best-corrected visual acuity, central corneal thickness, keratometry (K), and refractive error values of each group were recorded and compared. Seventy-eight eyes (41 in group 1 and 37 in group 2) were included in this study. The mean follow-up period of the patients was 37.7 ± 30.0 months in group 1 and 51.2 ± 29.4 months in group 2 ( P = 0.06). The preoperative and postoperative best-corrected visual acuity and central corneal thickness values were statistically similar in both groups (each P value >0.05). Keratometry values (K1 and mean keratometry) were significantly steeper in group 1 ( P1 = 0.02 and P2 = 0.03, respectively). Descemet membrane perforation was experienced in 7 (4 macroperforation and 3 microperforation; 15.6%) of 45 eyes that planned to perform DALK. These 4 eyes with macroperforation underwent PK and were excluded from the study. When all postoperative complications were assessed, although the total complication rate was 21% after DALK, it was 43% after PK ( P = 0.04). DALK with a big-bubble technique is a feasible surgery in eyes with corneal scarring due to previous hydrops and is comparable with PK in terms of visual and refractive outcomes. This study suggests that DALK, which is safer than PK with less postoperative complication rates, should be the primary surgical option to avoid serious complications in keratoconic eyes with hydrops-related corneal scarring.

The Incidence and Severity of Myopia in the Population of Medical Students and Its Dependence on Various Demographic Factors and Vision Hygiene Habits

(1) Background: Myopia is one of the leading causes of visual impairment. Visual work and usage of electronic devices are known risk factors of myopia. Many education systems were forced to apply online and hybrid teaching methods, to reduce the number of new cases of COVID-19. Medical students are a population well-known for intense visual work in the form of learning; (2) Methods: Visual acuity and refractive error were measured in the population of medical students. Participants also filled out the survey that included their population characteristic and their habits related to the hygiene of vision; (3) Results: We found a correlation between the age of the first diagnosis of myopia and current values of refractive error. The majority of participants believe that the COVID-19 pandemic had an impact on the health of their vision. Among methods of studying, usage of the computer screen was less preferred by myopic students; (4) Conclusions: In the population of medical school students in Eastern Poland, visual acuity was lower than 1.0 in 232 (52.97%) in the right eye and 234 (53.42%) in the left eye. Early recognition of refractive error has influenced its current values. Among methods of studying, usage of the computer screen was less preferred by myopic students. More population-based studies should focus on the impact of the COVID-19 pandemic on the health of vision.

Myopia progression in children before and after the coronavirus disease lockdown

Background: The worldwide spread of the coronavirus disease (COVID-19) pandemic in 2020, followed by lockdowns, forced children to be in home confinement with increased screen time, leading to rapid progression of myopia and an increase in the prevalence of myopia. This study was aimed at determining if myopia progression seen in evidence-based practice resulted from the COVID-19 lockdown or delayed follow-ups.&#x0D; Methods: A retrospective review of case sheets of patients visiting the pediatric department of a tertiary care eye hospital in Mumbai, India, was conducted from 2017 onwards. We enrolled all children with myopia who had attended at least one follow-up visit before the COVID-19 lockdown and at least one follow-up visit post-lockdown. The spherical equivalent (SEQ) of refractive error values at baseline and pre- and post-COVID-19 lockdown follow-ups (hereinafter referred to as the “first” and “second” follow-ups, respectively) were recorded. The duration between baseline and the first follow-up visit and between the first and second follow-up visits were noted.&#x0D; Results: We enrolled 112 eyes of 56 children, including 35 (62.5%) boys and 21 (37.5%) girls, with a mean (standard deviation [SD]) age of 9.54 (2.82) years. The mean (SD) SEQ values at baseline and first and second follow-ups were - 4.74 (3.83), - 5.46 (3.81), and - 6.42 (3.66) D, respectively. The mean change in SEQ, mean SEQ myopia progression, and rate of myopia progression per month differed significantly between the baseline and the first follow-up visit versus between the first and second follow-ups (all P &lt; 0.05). However, the change in myopia degree did not differ significantly between these two periods in eyes with low, moderate, or high myopia (all P &gt; 0.05). The mean (SD) duration between the baseline and the first follow-up visit was 14.57 (5.68) months, while that between the first and second follow-ups was 27.96 (9.18) months, showing a significant difference (P &lt; 0.05).&#x0D; Conclusions: Our findings suggest that a longer gap between follow-up visits and myopia progression per month should be factored into the management of myopia. Considering that young children are more vulnerable, preventive measures and school reforms should be urgently implemented in India. Further retrospective multicenter studies with a larger sample size of eyes, including various refractive errors over a longer period, are required to verify these findings.

Objective assessment of corneal backscattered light in myopic, hyperopic, and emmetropic children

BackgroundTo determine the corneal densitometry(CD) values by using Scheimpflug imaging in myopic and hyperopic children and to compare the results with emmetropic children. MethodsThe CD measurements of the subject were obtained with Scheimpflug tomography. The values were automatically measured in standardized grayscale units over an area 12mm in diameter, which was subdivided into 4 annular concentric zones(0-2mm, 2-6mm, 6-10mm, 10-12mm) and 3 corneal depths(anterior layer: anterior 120µm; central layer: from 120µm to the last 60µm; posterior layer: last 60µm). In addition, we evaluated the correlation between spherical equivalence and anterior corneal morphological parameters and the CD values. ResultsA total of 211 participants were included in this prospective cross-sectional study. The eyes were divided into three groups related to their spherical equivalent(SE) refractive error values as follows: 88(41.7%) hyperopic eyes, 62(29.4%) myopic eyes, and 61(28.9%) emmetropic control eyes. The hyperopic eyes were found to have lower corneal densitometry values in 4 annular zones and the total 0-12 diameter of all layers except the central layer. However, only the 6-10mm annular zone of the central and posterior layers of the myopic eyes had lower corneal densitometry values than emmetropic eyes. There was also a significant correlation between spherical equivalent and corneal densitometry values in the anterior layer(0-2mm, 2-6mm zones), central layer(0-2mm, 10-12mm zones), posterior layer(6-10mm, 10-12mm zones, and the total 0-12mm diameter), and total corneal thickness(0-2mm zone) of the hyperopic eyes. ConclusionsBackward scattering of light was lower in hyperopic eyes and this could indicate better visual quality.

Comparable postoperative myopic shift in eyes with retinal vascular diseases and vitreomacular interface diseases after phacovitrectomy.

To compare the predictive refractive error (PRE) of intraocular lens (IOL) power between retinal vascular and vitreomacular interface diseases after phacovitrectomy. We retrospectively reviewed patients who underwent phacovitrectomy for various retinal diseases. Patients with retinal vascular diseases and vitreomacular interface diseases were included in group A and group B, respectively. Age- and gender-matched senile cataract patients with phacoemulsification were set as controls. The mean PRE and absolute value of refractive error (ARE) among different groups were compared. The associated risk factors with ARE were also analyzed in the univariate and multivariate analyses. In total, 106 patients (Group A), 108 patients (Group B), and 110 patients as controls were included. The PRE in Group A (- 0.35 ± 0.83D) and Group B (- 0.53 ± 0.74D) were more myopic compared to the control group (- 0.11 ± 0.58D) (p < 0.05). The ARE in Group A (0.70 ± 0.57D) and Group B (0.75 ± 0.51D) were significantly higher compared to the control group (0.47 ± 0.35D) (p < 0.05). There were no significant differences in the PRE and ARE values between the two study groups (p = 0.267 and 0.861, respectively). There were no significant differences of the PRE and ARE in the eyes with silicone oil tamponade (- 0.63 ± 0.75D, 0.81 ± 0.54D) and gas tamponade (- 0.42 ± 0.83D, 0.74 ± 0.56D) (p = 0.693 and 0.988, respectively). In the multivariate model, preoperative LogMAR visual acuity (β = 0.162, 95%CI = 0.113-0.211, p < 0.001), mean corneal curvature (β = 0.105, 95% CI = 0.074-0.135, p < 0.001), and age (β = 0.012, 95% CI = 0.005-0.019, p = 0.001) were all positively correlated with the ARE. Postoperative myopic shift after phacovitrectomy may be comparable in retinal vascular diseases and vitreomacular interface diseases, no matter the gas or silicone oil tamponade. Older age, steeper corneal curvature, and worse preoperative visual acuity could produce more prediction errors.

Association Between Types of Posterior Staphyloma and Refractive Error After Cataract Surgery for High Myopia.

Purpose: To investigate the association between different types of posterior staphyloma (PS) and refractive error (RE) after cataract surgery in patients with high myopia.Methods: This retrospective study included 113 eyes of 113 highly myopic patients with PS. PS was detected using a wide-field fundus imaging system. PS was classified into wide macular, narrow macular, and other types. RE equaled the actual spherical equivalent (SE) minus the targeted SE values 3 months after cataract surgery.Results: The rates of wide macular, narrow macular, and other types of PS were 46.02, 39.82, and 14.16%, respectively. There were no significant differences in best corrected distance visual acuity (BCDVA) or SE among the three classifications of PS before cataract surgery (P > 0.05). However, postoperative BCDVA and SE were significantly different among the three types of PS patients (P < 0.05). The average RE values were 0.98 ± 1.00 D, 0.19 ± 0.87 D, 0.13 ± 0.59 D, respectively; the statistical differences of RE were <0.01, <0.01, and 0.81 (wide macular vs. narrow macular, wide macular vs. other types, narrow macular vs. other types), respectively. Multivariate linear regression analysis revealed that higher hyperopia RE after surgery was associated with wide macular staphyloma (P < 0.001), more myopic SE (P = 0.003), and increased BCDVA (P = 0.002) before surgery.Conclusions: Wide macular PS may be associated with more hyperopic RE; it may serve as a critical biomarker of hyperopic RE after cataract surgery in highly myopic patients.

Altered Expression of GJD2 Messenger RNA and the Coded Protein Connexin 36 in Negative Lens–induced Myopia of Guinea Pigs

Decreased expression of the retinal GJD2 gene messenger RNA (mRNA) and connexin 36 (Cx36) protein in the guinea pig negative lens-induced myopia (LIM) model suggests their involvement in local retinal circuits regulating eye growth. Previous studies suggest that the GJD2 gene and Cx36 protein encoded by the GJD2 gene play important roles in retinal signaling pathways and eye development. The aim of this study was to investigate the changes in GJD2 mRNA and Cx36 protein expression in the guinea pig lens-induced myopia model. Four-week-old guinea pigs were randomly divided into two groups. Animals in the experimental group were fitted with monocular -10 D lenses; and animals in the control group, with monocular plano lenses. Biometric measurements, including the spherical equivalent refractive error and axial length, were monitored. Animals were killed after 0, 1, 2, and 3 weeks of treatment, and their retinas were isolated. Retinal GJD2 mRNA and Cx36 protein expression levels were assessed by quantitative real-time polymerase chain reaction and Western blot analysis, respectively. Spherical equivalent refractive error values indicated that negative lens-treated eyes became significantly more myopic than plano lens-treated eyes (P = .001), consistent with their longer axial lengths compared with those of control eyes. Both GJD2 mRNA and Cx36 protein expression levels were decreased in the retinas of negative lens-treated eyes compared with levels in the retinas of plano lens-treated eyes, although there were differences in the timing; GJD2 mRNA, levels were significantly decreased after 1 and 2 weeks of treatment (P = .01 and P = .004, respectively), whereas Cx36 protein expression was significantly decreased after only 1 week (P = .01). That both retinal GJD2 mRNA and Cx36 protein expression levels were decreased after induction of myopia with negative lenses points to retinal circuits involving Cx36 in myopia development in the guinea pig.

Ocular Manifestations and Biometrics in Marfan's Syndrome from Eastern Nepal.

PurposeTo evaluate the ocular characteristics of Marfan’s syndrome (MFS) fulfilling the revised Ghent-2 nosology in Eastern Nepal.Materials and MethodsA hospital-based observational and cross-sectional study was conducted. Ocular manifestations and biometrics were incorporated. Patients were subdivided into adults (16 years or older) and children (5–15 years). Ocular biometric parameters consisted of values of refractive error, keratometry readings, anterior chamber depth (ACD), central corneal thickness (CCT), lens thickness (LT) and axial length (AL).ResultsA total of 34 eyes of 17 patients with MFS were included, where 32 eyes were phakic. Mean age of the study participants was 14.5 ± 9.1 years. The mean best corrected visual acuity (BCVA) of phakic eyes was 0.99 ± 0.82 LogMAR. Myopia greater than −3 diopters (D) was present in 28/34 (82.35%) eyes. The average spherical equivalent was −12.34 ± 8.85 D. Ectopia lentis (EL) was present in 24/32 (75%) eyes where superonasal was the most common subluxation in 10/24 (41.7%) eyes. AL was longer in adults 26.54 ± 4.42 mm compared to 25.21 ± 1.93 mm in children. Likewise, LT in adults was 4.9 ± 0.70 mm and 4.40 ± 0.59 mm in pediatric participants. Flat corneas were noted in both the groups with an average of 41.53 ± 2.21 D. The mean CCT and ACD were 524.62 ± 21.74 μm and 3.64 ± 0.80 mm, respectively. There was a negative association between the AL and the average corneal curvature (Kmed, correlation coefficient −0.11, p=0.54).ConclusionMyopia is the foremost ocular involvement with significant visual disability in MFS. Though, AL and corneal curvature are not included in the revised Ghent-2 nosology, we strongly recommend these parameters to be considered during ophthalmic evaluation in suspected and diagnosed cases of MFS in the absence of genetic testing.

Correlation of binocular refractive error and calculation of intraocular Lens power for the second eye

BackgroundReducing refractive error has always been a tricky problem. The aim of this study was to verify the correlation between binocular refractive error (RE) after sequential cataract surgery and explore an individualized calculation method of intraocular lens (IOL) for the second eye.MethodsThis was a prospective study. One hundred eighty-eight affected eyes in 94 age-related cataract patients who underwent sequential cataract surgery in the Department of Ophthalmology, Tangdu Hospital, China, were recruited. Complete case data were included for a correlation analysis of binocular RE. Data obtained in patients with RE values greater than 0.50 diopters (D) in the first eye were extracted and the patients divided randomly into two groups: Group A and B. In the adjustment group, group A, we modified the IOL power for the second eyes as 50% of the RE of the first eye. In group B, the control group, there was no modification. The mean absolute refractive error (MARE) values of the second eyes were evaluated one month after surgery.ResultsThe correlation coefficient of the binocular RE after sequential cataract surgery was 0.760 (P < 0.001). After the IOL power of the second eyes was adjusted, the MARE of the second eyes was 0.57 ± 0.41 D, while the MARE of the first eyes was 1.18 ± 0.85 D, and the difference was statistically significant (P < 0.001).ConclusionsBinocular REs were positively correlated after sequential cataract surgery. The RE of the second eye can be reduced by adjusting the IOL power based on 50% of the postoperative RE of the first eye.

Refraction under general anesthesia in children, using cycloplegic refraction only as a reference

ABSTRACT Purpose To compare the measurements of cycloplegic refraction and refraction (R1-1) under general anesthesia (GA) when using the same portable auto-refractometer (ARF) in pediatric patients. Methods 36Thirty-six to 60-month-old patients who underwent refraction measurements using a portable ARF (Retinomax® K plus 3, Righton, Japan), who did not receive prior cycloplegics under this GA and who had cycloplegic refraction using 1% cyclopentolate and the same Retinomax® device < 3 months prior this GA, between 2015 and 2018, were included in this study. The agreement (Bland-Altman analysis) and correlation (Pearson correlation) between the mean values of the measurements were analyzed. Results Two-hundred-twenty-two right eyes of 222 patients (114 male and 108 female) were included in this study. The mean age was 45.04 ± 11.24 months. The mean spherical refractions (R1-1, R2-1) under GA and cycloplegic refraction were 1.08 ± 3.50 diopter (D) (−8.00 to +8.00) and 2.58 ± 3.28 D (−6.50 to +9.25), respectively. A strong positive correlation was detected between the two measurements (r = 0.95). When comparing measurements, the mean measurement under GA was −1.49 D (95% confidence interval: lower limit, −3.63; upper limit, +0.63) more myopic than the mean cycloplegic refraction (R1-1) value (Bland-Altman analysis test). The differences between the measurements were within ± 1 D in 92 eyes (41.44%) and within ± 2 D in 180 eyes (81.01%). No significant difference was detected when comparing the cylindrical refractive error values (p > .05). Conclusion Refractive measurements under GA were more myopic than cycloplegic refraction (R1-1) measurements. It is important to consider that complete cycloplegia is not achieved under GA.

Profile of refractive error in Ekiti, south western Nigeria

Background: Refractive error is one of the eye disorders with the capability of causing visual impairment. We needed to know the various types and proportion of refractive errors seen in patients attending an eye clinic at the tertiary health centre.Aim: An observational study was carried out to determine the profile of refractive error in a southwestern Nigeria hospital.Methods: All new cases with the diagnosis of refractive error between January 2015 and December 2016 had autorefraction and subjective refraction to determine the types and values of refractive error. Data were analysed with SPSS 20. Statistical significance was inferred at p &lt; 0.05.Results: Refractive error constituted 618 (21.4%) of the total new cases. The mean age was 39.3 ± 22.96 years. The male to female ratio was 1:1.8. Children constituted 25.7% of all the cases. The most common refractive error was myopia in 64.3%. A total of 312 (50.5%) patients had other co-existing ocular disorders with allergic conjunctivitis on the top of the list. The number of visually impaired reduced to 70 (5.64%) after the correction of existing refractive error with about 94.1% having their visual acuity restored to normal.Conclusion: Refractive error was a common eye disorder among our patients with the proportion of children about a quarter of all patients. We recommend that childhood refractive errors should be given prioritised attention in eye outreach programmes.

A Comparative Study on the Effects of Vintage Nonpharmacological Techniques in Reducing Myopia (Bates eye exercise therapy vs. Trataka Yoga Kriya).

Background:Human eye captures light rays as they come and fall on the retina and convert them into an image. However, in myopia, light rays fall in front of retina, causing blurring of image. Correction of this is generally done using correcting devices such as corrective glasses and contact lenses. Existence of some alternative therapies is also noticed in literature.Aim:To compare the effects of Bates eye exercises and Trataka Yoga Kriya on myopia.Materials and Methodology:Ethical clearance was obtained from the institution, and informed consent was taken from participants. In this randomized comparative study, 24 participants (48 eyes) were taken based on inclusion and exclusion criteria and were randomly divided into two groups: Group A and Group B, where Bates eye exercise therapy and Trataka Yoga Kriya were given, respectively, for 8 weeks. Participants were assessed for their refractive errors and visual acuity pre- and post-intervention.Results:Data were analyzed by SPSS version 20. Results obtained revealed that both Bates exercises and Trataka Yoga Kriya were not significantly effective in reducing refractive errors and in improving visual acuity (P value of refractive error in right eye: 0.4250; left eye: 0.4596; P value of visual acuity in right eye: 0.5691; left eye: 0.8952).Conclusion:This study concludes that nonpharmacological approaches such as eye exercises and Trataka Yoga Kriya are not significant on myopia.

Aberrometry Repeatability and Agreement with Autorefraction.

Commercially available aberrometers are essential to clinical studies evaluating refractive error and image quality. The Discovery System (Innovative Visual Systems, Elmhurst, IL) is a promising clinical instrument that allows investigators to export aberration data for research and analysis purposes. An assessment of the Discovery System's performance is essential to the interpretation of the data obtained. The aims of this study were to determine the between-visit repeatability of refractive error and higher-order aberration measurements with the Discovery System and to examine between-instrument agreement of refractive error measurements with the Discovery System and Grand Seiko WAM-5500 open-field autorefractor (Grand Seiko Co., Hiroshima, Japan). Cycloplegic refractive error values from the Discovery System (over a 3-mm pupil) and the Grand Seiko autorefractor were converted to power vectors (M, J0, and J45), and averaged. Zernike coefficients were also calculated by the Discovery System over a 6-mm pupil through the sixth radial order. Between-visit repeatability and agreement were evaluated using Bland-Altman difference-versus-mean plots. A t-test compared each mean difference (bias) to zero, and the 95% limits of agreement were calculated. Twenty-five young adults with a mean (±SD) cycloplegic spherical-equivalent refractive error of -2.91 ± 1.85 diopters (D) (range, -6.96 to +0.74 D) were enrolled. There were no significant between-visit differences with the Discovery System for M, J0, J45, third- through sixth-order root mean square (RMS), higher-order RMS, or spherical aberration (all P > .30), and the repeatability for defocus and higher-order RMS were ±0.31 D and ±0.095 μm, respectively, for a 6-mm pupil. At a 3-mm pupil, the Discovery System, on average, measured slightly more positive values than the Grand Seiko for M (0.28 D), J0 (0.11 D), and J45 (0.12 D; all P < .005). The Discovery System was very repeatable and would be an appropriate instrument to measure cycloplegic refractive error and higher-order aberration changes in adults. Small differences in refractive error were found between the Discovery System and Grand Seiko.

Refractive status of primary, middle and senior high school students in Shanghai

Aim: To investigate the refractive status in Chinese students ages 7 through 18 years old and to study influencing factors, such as age and gender. Methods: A total of 748 students (748 eyes) from the primary school group (PS: 483 eyes), middle school group (MS: 78 eyes) and senior high school group (SHS: 187 eyes) were included in this prospective observational case series study. The refractive error values were determined using an automatic refractometer. The spherical refractive error, cylinder power and axis were measured by non-cycloplegic screening. Results: For spherical error comparison, significant differences existed between every two groups. The SHS showed more negative spherical values compared with the PS (p < 0.001) and MS (p < 0.001). The myopia prevalence of MS (97.4%) was significantly higher compared with the PS (70.0%) and SHS (80.2%). The high myopia prevalence of SHS (19.3%) was significantly higher compared with the PS (0.6%) and MS (2.6%). Age was negatively correlated with the spherical error (r = -0.666, p < 0.001). Nevertheless, gender had no correlation with it. Conclusions: With age and studying level increasing, Shanghai urban Chinese students ages 7 through 18 years old showed increasing tendencies towards myopia and high myopia. Thus, closer attention should be paid on the refractive status of this population.

Evaluation of Ocular Side Effects in the Patients on Topiramate Therapy for Control of Migrainous Headache.

Topiramate, a sulfa-derivative monosaccharide, is an antiepileptic drug which is administered in the control of migraine. It is reported to cause various ocular side effects such as visual field defect and myopic shift. To investigate the alterations in refractive error, properties of the cornea and changes in the anterior chamber in patients that receive Topiramate for migraine control. This is a hospital-based, non-interventional, observational study that is conducted at Imam Hossein Hospital, affiliated to Shahid Beheshti University of Medical Sciences, Department of Neurology, in collaboration with the department of Ophthalmology. Thirty three consecutive patients with the diagnosis of migraine that were candidate for Topiramate therapy were recruited. Patients with history of ocular trauma or surgery, keratoconus, glaucoma, congenital ocular malformations and any history of unexplained visual loss were excluded. After thorough ophthalmic examination, all the patients underwent central corneal thickness (CCT) measurement, and Pentacam imaging (Scheimpflug camera) at the baseline. Various parameters were extracted and used for analysis. Anterior chamber volume (ACV), anterior chamber depth (ACD), and anterior chamber angle (ACA) measurement was performed. These measurements were repeated on day 30(th) and 90(th) after the initiation of Topiramate therapy. According to the normality tests, parameters with normal distribution were analysed using the repeated measures test and the remaining parameters (with non-normal distribution) were analysed using the non-parametric k-sample test. A p-value< 0.05 was considered statistically significant, according to Bonferroni post hoc correction. There were 66 eyes of 33 patients under the diagnosis of migrainous headache, that Topiramate was initiated for headache control, included in the study. The mean value of refractive error had a statistically significant myopic change, from -0.23 diopters (D) at the baseline to -0.61 D at the 90(th) day of follow-up period (p-value < 0.001). Mean CCT was 531.43 μm at the baseline and increased to 534.72 μm at the 30(th) day, and 537.51 μm at the 90(th) day after the administration of Topiramate (p-value=0.001). Mean value of other parameters, ACV, ACD, and ACA, did not reveal statistically significant change. Myopic shift and gradually increasing CCT in the patients after Topiramate administration should be considered before any refractive surgery. We found no gradual change in the anterior chamber and angle parameters in our patients in the 90 days of follow up. More studies with a longer duration of follow-up are needed to elucidate dose-dependent ocular manifestations.

Refractive errors and their effects on visual evoked potentials

In view of the increasing use of visual evoked potentials (VEP) technique in neuro-ophthalmological diagnosis, it was thought pertinent to appraise the changes brought about in VEPs in the presence of refractive error (RE) as studied by the vision researchers and neurophysiologists. The purpose of this review was to provide a comprehensive quintessence of the work carried out in this fi eld with an attempt to summarize the previous concepts, recent perspective and current notion about the value of RE in electrophysiologic testing particularly the VEP technique.