Changes in axial length in anisometropic children wearing orthokeratology lenses.

Purpose: There is a particular anisometropia occurring in one eye with myopia, while the other eye has very low myopia, emmetropia, or very low hyperopia. It is unclear how the binocular axial length changes when these children wear unilateral OK lenses only in the more myopic eyes. This study investigates the changes in the axial elongation of both eyes. Methods: This is a 1-year retrospective study. In total, 148 children with myopic anisometropia were included. The more myopic eyes were wearing orthokeratology lenses (treated eyes), whereas the contralateral eyes were not indicated for visual correction (untreated eyes). The untreated eyes were classified into three subgroups based on the spherical equivalent refraction (SER): low myopia (≤ -0.50 D, n = 37), emmetropia (+0.49 to -0.49 D, n = 76), and low hyperopia (≥0.50 D, n = 35). Changes in the axial length (AL) were compared between the untreated and treated eyes and among the three subgroups. Results: The axial elongation was 0.14 ± 0.18 mm and 0.39 ± 0.27 mm in all treated and untreated eyes, respectively (p < 0.001). The interocular AL difference decreased significantly from 1.09 ± 0.45 mm at the baseline to 0.84 ± 0.52 mm at 1 year (p < 0.001). The baseline median (Q1, Q3) SER of the untreated eyes were -0.75 D (-0.56, -0.88 D), 0.00 D (0.00, -0.25 D), and +0.75 D (+1.00, +0.62 D) in low myopia, emmetropia, and low hyperopia subgroups, respectively. The axial elongation was 0.14 ± 0.18 mm, 0.15 ± 0.17 mm, and 0.13 ± 0.21 mm (p = 0.92) in the treated eyes and 0.44 ± 0.25 mm, 0.35 ± 0.24 mm, and 0.41 ± 0.33 mm in the untreated eyes (p = 0.11) after 1 year. Multivariate linear regression analyses only showed significant differences in axial elongation between the emmetropia and low myopia subgroups of untreated eyes (p = 0.04; p > 0.05 between other subgroups). Conclusion: Unilateral orthokeratology lenses effectively reduced axial elongation in the more myopic eyes and reduced interocular AL differences in children with myopic anisometropia. The refractive state of the untreated eyes did not affect the axial elongation of the more myopic eye wearing the orthokeratology lens. In the untreated eyes, AL increased faster in the low myopia subgroup than in the emmetropia subgroup.

Comparison of Ocular Biomery in Primary Open Angle Glaucoma and Non-glaucoma in South West Nigeria.

Background: Glaucoma is a public health problem in Nigeria. The number of individuals affected by glaucoma in Nigeria is much higher than the individuals known to have the disease. Ocular parameters such as intraocular pressure, central cornea thickness, axial length and refractive error have all been documented as risk factors of glaucoma especially among Caucasians and African Americans, with little documentation in Africa where there's an alarming rate of blindness. Aim and Objectives: To compare central cornea thickness (CCT), intraocular pressure (IOP), axial length (AL) and refractive state in participants with primary open angle glaucoma (POAG) and non-glaucoma in South-West Nigeria. Materials and Methods: This hospital-based case-control study was carried out among 184 newly diagnosed POAG and non-glaucoma adult participants attending the outpatient clinic of Eleta eye institute. The CCT, IOP, AL and refractive state were measured in each participant. Test of significance between proportions in categorical variables were assessed using chi square test (χ2) in both groups. The means were compared using independent t-test while correlation between parameters were analyzed using Pearson correlation coefficient. Results: The mean age of the POAG participants was 57.16 + 13.3 years and the mean age of the non-glaucoma participants was 54.15 + 13.4 years. The mean IOP in the POAG group was 30.2 + 8.9mmHg while non- glaucoma group was 14.2 + 2.6mmHg (P < 0.001), other ocular parameters were not significantly different in both groups. In the POAG group, decreased spherical equivalent refractive error (i.e increasing myopia) was significantly associated with increased axial length (r= -0.252, P = 0.01), but not significant in the non- glaucoma group. However, in the non-glaucoma group, central cornea thickness increased with increasing intraocular pressure (r= 0.305, P = 0.003), which was not significant in the glaucoma group. Conclusion: Patients with POAG had much higher IOP and thus, IOP remains a significant risk factor in its development. There was a significant relationship between refractive state and axial length in the POAG group while a significant relationship was identified between central cornea thickness and intraocular pressure in the non- glaucoma group.

Prediction of spherical equivalent difference before and after cycloplegia in school-age children with machine learning algorithms.

Purpose: To predict the need for cycloplegic assessment, as well as refractive state under cycloplegia, based on non-cycloplegic ocular parameters in school-age children. Design: Random cluster sampling. Methods: The cross-sectional study was conducted from December 2018 to January 2019. Random cluster sampling was used to select 2,467 students aged 6-18 years. All participants were from primary school, middle school and high school. Visual acuity, optical biometry, intraocular pressure, accommodation lag, gaze deviation in primary position, non-cycloplegic and cycloplegic autorefraction were conducted. A binary classification model and a three-way classification model were established to predict the necessity of cycloplegia and the refractive status, respectively. A regression model was also developed to predict the refractive error using machine learning algorithms. Results: The accuracy of the model recognizing requirement of cycloplegia was 68.5-77.0% and the AUC was 0.762-0.833. The model for prediction of SE had performances of R^2 0.889-0.927, MSE 0.250-0.380, MAE 0.372-0.436 and r 0.943-0.963. As the prediction of refractive error status, the accuracy and F1 score was 80.3-81.7% and 0.757-0.775, respectively. There was no statistical difference between the distribution of refractive status predicted by the machine learning models and the one obtained under cycloplegic conditions in school-age students. Conclusion: Based on big data acquisition and machine learning techniques, the difference before and after cycloplegia can be effectively predicted in school-age children. This study provides a theoretical basis and supporting evidence for the epidemiological study of myopia and the accurate analysis of vision screening data and optometry services.

Analysis of refractive state screening and glasses wearing rate of students aged 6～18 in Yecheng county, Xinjiang / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the refractive status and myopia wearing rate of primary and secondary school students aged 6-18 in Yecheng county, Xinjiang.METHOD: Cross-sectional study. From October 2021 to June 2022, a stratified random sampling method was used to select 81 863 students from 51 primary schools and 30 secondary schools in Yecheng county, Kashgar Prefecture, Xinjiang. Basic data of the students were collected, and non ciliary muscle paralysis optometry was performed to detect naked eye farsightedness and corrected vision with glasses. The refractive status, glasses wearing rate, and full correction rate of students of different ages, genders, and ethnic groups were observed.RESULT: The detection rate of myopia among enrolled students was 13.39%(10958/81863), the wearing rate of glasses was 23.96%(2626/10958), and the full correction rate was 50.57%(1328/2626). The detection rate of myopia shows a certain upward trend with age, and the detection rate of myopia in girls was higher than that in boys(15.75% vs. 10.96%). The detection rates of myopia in Han, Uyghur, and other ethnic students were 68.12%, 12.63%, and 22.42%, respectively.CONCLUSION:The detection rate of myopia and glasses wearing rate were relatively low for students aged 6～18 in Yecheng county, Xinjiang, while the detection rate and glasses wearing rate of myopia among Han students were significantly higher than those of Uyghur and students of other ethnics.

Investigation and analysis of refraction state of primary school students in Haicheng district, Beihai city / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To understand the prevalence of refractive state of primary school students in Haicheng district, Beihai city.<p>METHODS: Cross-sectional study and cluster sampling were used. A total of 30 716 students aged 6 to 14 from 15 primary schools in Haicheng district, Beihai city, who had taken physical examination from October 2019 to January 2020, were selected for visual acuity and pupil diopter. SPSS17.0 statistical software was used for data analysis.<p>RESULTS: In the eyes of the 15 primary schools monitored in this study, 30 716 cases had mild myopia(29.62%), 0.50D < astigmatism < 2.00D(25.43%), metropia(21.05%)and mild hyperopia(15.85%). With the growth of age, the proportion of emmetropia and farsightedness declined as awhole. The proportion of myopia is on the rise. A total of 1 894 cases of wearing glasses 3 788 eyes. The rate of poor vision was 23.30%, and the rate of qualified correction of frame glasses was 64.57%. Compared with the left eye, the difference was statistically significant, and the <i>P</i>50 of the right eye was more negative than that of the left eye. The equivalent spherical mirror was compared between boys and girls. The difference was statistically significant, and the <i>P</i>50 of equivalent spherical mirror of girls was more negative than that of boys.<p>CONCLUSION: With the growth of age, the proportion of mild hyperopia and squarely eyes decreases year by year; The proportion of myopia increases year by year; Among the students with poor eyesight, the number of those who regularly wear glasses is small; However, after wearing glasses, there are still some students whose glasses are not up to standard. The refractive state of the right eye is more negative than that of the left eye; Female students tend to be more negative than male students in the refractive state.

Corneal curvature and refractive state changes after microscopically extraocular muscle surgery in adults / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To investigate the corneal curvature and refractive changes after microscopically extraocular muscle surgery in adults.<p>METHODS: To observe 62 cases of 85 eyes underwent microscopic extraocular muscle surgery in the Second People's Hospital of Yunnan Province from December 2016 to May 2017, age 18 to 43, according to the surgical method, patients were divided into horizontal rectus surgery: Ⅰ group(simple migration group)32 eyes, Ⅱ group(rectus monocular migration combined with its antagonist muscle excision group)34 eyes, the oblique muscle group: Ⅲ group(single oblique muscle tendon broken group)10 eyes, Ⅳ group(oblique muscle transposition group)9 eyes; Subjective optometry was performed preoperatively and postoperatively at 1d, 1wk, 1mo, 3mo and 6mo, respectively, to obtain the refractive state changes and the curvature value of the anterior surface of the cornea(0-3mm, 5mm, 7mm)collected by corneal topography. The dynamic changes of the refractive state and corneal morphology of the patients in each group at different time points were compared. Anova and LSD-<i>t</i> test were used for comparison among time points and within each group.<p>RESULTS: Changes of corneal curvature in horizontal rectus muscle can be induced in a short period after the operation, which is limited to the central 5mm area of the cornea, and basically restored to the preoperative level 1mo after the operation. There was no significant effect on corneal curvature after inferior oblique operation. Astigmatism value increased in the early postoperative period of horizontal rectus muscle; Myopic drift occurred and recovered to preoperative level 1mo after surgery. After the operation of the inferior oblique muscle, there was no significant change in the spheroscopy and astigmatism.<p>CONCLUSION:Corneal curvature and refractive changes may occur after extraocular muscle in adults.

Conserved characteristics of ocular refractive development - Did the eye evolve once?

It has been speculated that the unitary eyes of vertebrates and molluscs, and the compound eyes of insects and crustaceans, evolved separately. On the other hand, the common use of rhodopsin as a photoreceptor molecule, and the conservation of Pax6 as a master control gene for eye development, suggest instead that the eye evolved once. Yet, recently the molecular genetics that had seemed to suggest a definitive answer to this evolutionary point has once again become cloudy. Here we propose an alternative approach to addressing the question of eye evolution through comparative analyses of physiological optics. Serendipitous discoveries involving form deprivation and defocusing with young monkeys and chicks demonstrated the conserved importance of visual experience on eye development. Similar results have been demonstrated in teleosts, although differences exist in eye anatomy, physiology and optics. In particular, since fish grow throughout life, these effects can also be demonstrated in adults. In comparison, the cephalopod eye is an often-cited example of convergent evolution with the vertebrate eye, although considerable developmental differences exist. Nevertheless, squid eyes from animals raised under alternative lighting exhibit anatomical and refractive changes that agree with those found in vertebrates. Together, these observations provide functional and structural support for the view that the eye evolved once. Because of their very compressed lifespans (only one to two years) cephalopods may be ideal animal models for the study of ocular refractive development.

Analysis of ocular biometric parmeters in hyperopia preschool children / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To measure and analyze the relationship between ocular biometric parameters and refractive status in hyperopia preschool children.<p>METHODS: Two hundred and three cases(405 eyes)of hyperopia were included in this study, who were diagnosed in Northwest Women and Children Hospital from January 2016 to December 2018.According to different mean spherical equivalent(SE)diopter, the children were divided into mild hyperopia, moderate hyperopia and high hyperopia groups though the retinoscopy after cycloplegia. Anterior chamber depth(ACD), lens thickness(LT), vitreous depth(VITR)and axial length(AL)were measured by A-scan. The value of K1, K2 were got by computer refractor. And analyze the relationship between ocular biometric parameters and refractive. <p>RESULTS: The mean anterior chamber depth for hyperopia preschool children was 3.08±0.38mm, the lens thickness was 3.91±0.34mm, the vitreous depth was 14.53±1.85mm, the axial length was 21.45±1.01mm and the average cornea K was 43.34±1.70D; There were statistically significant differences in AL and VITR among the three hyperopia groups(<i>P</i><0.05). There were statistically significant difference in LT between low hyperopia and moderate hyperopia, moderate hyperopia and high hyperopia(<i>P</i><0.05). There were statistically significant difference in ACD between low hyperopia and moderate hyperopia(<i>P</i><0.05). No difference in K was found across the three groups(<i>P</i>>0.05); SE was negatively correlated with AL and ACD(<i>P</i><0.01), but had no correlation with ACD, LT and K(<i>P</i> >0.05).<p>CONCLUSION: The change of AL plays an important role affecting the refractive state of preschoolers with hyperopia ametropia, which is manifested as higher the hyperopia diopter, the shorter AL and the shallower vitreous cavity, which are co-involved in the change of refractive state, while the hyperopic degree had no correlation with ACD, LT and K. The axial refractive error is the main refractive error in preschoolers.

Refractive state and its factors of low birth weight infants aged 3-6 years / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To investigate the refractive state and related factors of low birth weight infants aged 3-6 years old.<p>METHODS: During the study period from March to June 2018, 144 cases of low birth weight infants in 8 kindergartens were randomly selected as study group. The normal birth weight of the same kindergarten was randomly selected according to the 1:1 pairing principle as control group. The refractive status and eye biometrics of the two groups were compared. The factors related to the equivalent spherical power of low birth weight were analyzed.<p>RESULTS: Among the children of all ages, the spherical degree and the equivalent spherical degree of the study group were lower than the control group. The corneal curvature was higher than that of the control group. There were significant differences of the axial length and the cylindrical degree between the two groups for 5-6 years old children(<i>P</i><0.05). After multiple regression, the equivalent spheroscopy degree =-10.491-0.442×age+0.765×gestational age+5.860×birth weight-1.529×axial length +0.547×corneal curvature(<i>R2</i>=0.823, <i>P</i><0.001).<p>CONCLUSION: The trend of myopic refractive error and astigmatism in children with low birth weight of 3-6 years old is higher than that of normal birth weight. The refractive error is closely related to age, gestational age, birth weight, axial length and corneal curvature, which requires early monitoring and intervention.

lnfluence on long - term changes of refractive status in children after congenital cataract intraocular lens implantation / 国际眼科杂志(Guoji Yanke Zazhi)

To discuss long-term changes of refractive status in children after congenital cataract intraocular lens ( lOL) implantation and analyze its related influence factors.METHODS: Seventy cases ( 110 eyes ) with congenital cataract from January 2013 to January 2014 in our hospital were selected, according to the age of patients, they were divided into group A (0. 05 );The differences had statistical significances of the corneal curvature of group A after surgery and 3mo after operation (P0. 05);the corneal curvature 3mo after operation of group A was significantly higher than that of groups B and C (P0. 05 ); There were no statistical significances on axial length after operation in groups A, B, and C (P>0. 05);Ocular axial length difference of group A 3mo after surgery was significantly higher than that of groups B and C ( P 0. 05). Refractive status of three groups after operation showed myopia moving trend, refractive change rate and refractive diopter of group A after operation was significantly higher than that of group B, group C, the difference was statistically significant (P<0. 05). CONCLUSlON: After congenital cataract extraction combined with lOL implantation, patients present myopia refractive state trend. Performance of children below 2 years old is significant. The main factor of myopia is axial growth.

A retinoscopic survey of 333 horses and ponies in the UK.

INTRODUCTION: Ophthalmic examination in the horse is generally limited to crude assessment of vision and screening for ocular lesions. The refractive state of equine eyes and the potential impact on vision and performance requires further investigation. OBJECTIVE: To assess the refractive state of a large, mixed-breed sample of horses and ponies in the United Kingdom (UK). PROCEDURE: The refractive state of both eyes of 333 horses and ponies was determined by streak retinoscopy, and the effect of age, height, gender, breed and management regime on the refractive state assessed. RESULTS: Emmetropia was found in 557 of 666 (83.63%) of eyes; 228/333 (68.5%) of the horses/ponies were emmetropic in both eyes. Refractive errors of greater than 1.50 D (in either direction) were found in 2.7% of the eyes tested. Ametropic eyes included hyperopia (54%) and myopia (46%). Anisometropia was found in 30.3% of horses and ponies. Breed of horse/pony was the only factor that affected refractive state (in the left eye only, P < 0.05) with Thoroughbred crosses having a tendency toward myopia and Warmbloods/Shires toward hyperopia. DISCUSSION AND CONCLUSION: The retinoscopic survey found emmetropia to be the predominant refractive state of the equine eye with no evidence of an overall trend toward myopia or hyperopia. However, individual and breed-related differences were found. Such factors should be considered in the selection of horses for sport and leisure, and when evaluating their performance potential. More comprehensive visual testing would be valuable in identifying underlying causes of behavioral problems.

The effect of various levels of stroboscopic illumination on the growth of guinea pig eyes.

BACKGROUND: The aim was to investigate various levels of stroboscopic illumination effect on the growth of guinea pig eyes. METHODS: Thirty-six two-week-old guinea pigs were randomised to one of three treatment groups (n = 12 for each). Two stroboscopic-reared groups were raised with a duty diurnal cycle of 50 per cent at a flash rate of 0.5 Hz. Illumination intensity varied between zero-to-250 lux or zero-to-500 lux during each cycle in each group, respectively. The third control group was exposed to 250 lux illumination. Refraction and biometric measurements were taken for each animal prior to and after two, four, six and eight weeks of treatment. Finally, retinal microstructure was examined. RESULTS: There was significant correlation between refractive errors and axial elongation. After eight weeks of treatment, illumination with flickering light 0-250 lux caused a larger myopic shift with increased axial length than illumination of continuous 250 lux. Stroboscopic illumination with zero-to-500 lux caused a further myopic shift and longer axial length than stroboscopic illumination with zero-to-250 lux. In animals raised in flickering light of zero-to-250 lux or zero-to-500 lux for eight weeks, the outer segment disc membranes in photoreceptor layers were found deformed and detached. CONCLUSION: Chronic exposure to low-frequency temporally modulated illumination-induced histological damage in the retina and induced exaggerated axial length elongation.

Eye laterality: a comprehensive analysis in refractive surgery candidates.

PURPOSE: To explore eye laterality (higher refractive error in one eye) and its association with refractive state, spherical/astigmatic anisometropia, age and sex in refractive surgery candidates. METHODS: Medical records of 12 493 consecutive refractive surgery candidates were filtered. Refractive error (subjective and cycloplegic) was measured in each subject and correlated with eye laterality. Only subjects with corrected distance visual acuity (CDVA) of >20/22 in each eye were enrolled to exclude amblyopia. Associations between eye laterality and refractive state were analysed by means of t-test, chi-squared test, Spearman's correlation and multivariate logistic regression analysis, respectively. RESULTS: There was no statistically significant difference in spherical equivalent between right (-3.47 ± 2.76 D) and left eyes (-3.47 ± 2.76 D, p = 0.510; Pearson's r = 0.948, p < 0.001). Subgroup analysis revealed (I) right eye laterality for anisometropia >2.5 D in myopic (-5.64 ± 2.5 D versus -4.92 ± 2.6 D; p = 0.001) and in hyperopic (4.44 ± 1.69 D versus 3.04 ± 1.79 D; p = 0.025) subjects, (II) a tendency for left eye cylindrical laterality in myopic subjects, and (III) myopic male subjects had a higher prevalence of left eye laterality. (IV) Age did not show any significant impact on laterality. CONCLUSIONS: Over the full refractive spectrum, this study confirmed previously described strong interocular refractive correlation but revealed a statistically significant higher rate of right eye laterality for anisometropia >2.5 D. In general, our results support the use of data from one eye only in studies of ocular refraction.

Quantitative Analysis of Changes of Automated Perimetric Thresholds after Pupillary Dilation and induced Myopia in Normal Subjects

We quantitatively analyzed the changes of the(retinal) threshold sensitivities between normal status and dilated emmetropic status, and between dilated emmetropic status and -1.0D induced myopic status. Three consecutive visual field examinations by Humphrey Field Analyzer C-30-2 threshold test and STATPAC program were performed in 36 eyes of 21 normal subjects who ranged in age from 23 to 40 years. The results were as follows: 1) There was a statistically significant decrease (0.87 +/- 0.91dB) in the mean threshold sensitivity within the central 30 degrees at the dilated emmetropic status(27.90dB) as compared with the normal status(28.77dB) (p=0.0001). 2) There was a statistically significant decrease(0.99 +/- 0.61dB) at -1.0D induced myopic status(26.91dB) as compared with the dilated emmetropic status(27.90dB) (p=0.0001). 3) After dilation, the mean threshold sensitivity between 20 and 30 degrees of field showed statistically significant decrease as compared with thosE' within the central 20 degrees of visual field(p0.05). Therefore, we emphasize the importance of consistent pupillary size and correct refractive state in performing the serial automated visual field tests.

Quantitative analysis of changes of automated perimetric thresholds after pupillary dilation and induced myopia in normal subjects

We quantitatively analyzed the changes of the (retinal) threshold sensitivities between normal status and dilated emmetropic status, and between dilated emmetropic status and -1.0D induced myopic status. Three consecutive visual field examinations by Humphrey Field Analyzer C-30-2 threshold test and STATPAC program were performed in 36 eyes of 21 normal subjects who ranged in age from 23 to 40 years. The results were as follows: 1) There was a statistically significant decrease (0.87 +/- 0.91dB)in the mean threshold sensitivity within the central 30 degrees at the dilated emmetropic status (27.90dB) as compared with the normal status (28.77dB)(p = 0.0001). 2) There was a statistically significant decrease(0.99 +/- 0.61dB) at -1.0D induced myopic status(26.91dB) as compared with the dilated emmetropic status(27.90dB)(p = 0.0001). 3) After dilation, the mean threshold sensitivity between 20 and 30 degrees of field showed statistically significant decrease as compared with those within the central 20 degrees of visual field(p 0.05). Therefore, we emphasize the importance of consistent pupillary size and correct refractive state in performing the serial automated visual field tests.

Clinical Study of Domestic-made Intraocular Lens(UNI-IOL(R))

I studied twenty cases who underwent domestic-made intraocular lens(IOL; UNI-IOL(R)) implantation from 12th April, 1988 to July 29, 1988. All patients most of them were females, were over 60 years old and followed up over 1 year. The results were as follows: 1. The postoperative final corrected visual acuity of 20/40 or better was noted in 18 eyes(90.0%) and visual acuity below 20/50 was in 2 eyes(10.0%). The reason's of this poor vision were optic atrophy and age related macular degeneration. 2. The final refractive state within +/-1.0D with spherical equivalent was fifty-five percent and only one over -2.0D. 3. The corneal thickness increased mostly(9.8%) at postoperative 3 days and graually returned to the normal level by postoperative fifteen days. 4. Anterior chamber reaction, cells, pigments on the IOL decreased gradually at postoperative period. 5. The percentage loss of corneal endothelium was 13.4% at postoperative 2 months and 14.1% at postoperative 1 year. 6. Partial posterior capsule rupture was developed in one eye during the opera tion and fibrinous membrane and after cataract were developed in one eye.