Comparison of the effects of different chromatic lights on accommodative response and microfluctuation in myopes and emmetropes / 中华实验眼科杂志

Objective:To explore the effects of conflicting stimuli generated by different chromatic lights on visual display terminal (VDT) on accommodative response and microfluctuation of myopes and emmetropes, and to investigate the possible relationship between chromatic light, accommodation and the development and progression of myopia.Methods:A non-randomized controlled trial was conducted.Forty-one subjects aged 22 to 30 years old were enrolled, including 19 emmetropes in emmetropic group and 22 myopes in myopic group.The subjects had the normal color vision and no ocular organic diseases.The interventions were screens of different colors.There were 7 chromatic light conditions, including 3 monochromatic lights (red, green, blue), 3 bichromatic lights (red+ green, red+ blue, green+ blue) and 1 polychromatic light (white=red+ green+ blue). Subjects were asked to look at a black E target on a VDT at a distance of 33 cm for more than 20 seconds.The background color of the VDT was changed randomly in the 7 chromatic light conditions.The accommodative responses were recorded with the Grand Seiko WAM-5500 automatic infrared refractor every 0.2 seconds and the accommodative microfluctuation was calculated as the standard deviation of the accommodative response.Accommodative response and accommodative microfluctuation under different chromatic light conditions were compared.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of the First Affiliated Hospital, Zhejiang University School of Medicine (No.2019-1564). Written informed consent was obtained from each subject.Results:No statistically significant difference was found in the accommodative response between the two groups ( Fgroup=2.626, P=0.113). There was a statistically significant difference under different chromatic light conditions between the two groups ( Flight=39.070, P<0.01). There were similar trends in the effects of various color lights in both groups, with the largest accommodative response under monochromatic red light, followed by the bichromatic light containing red light, and then the smallest accommodative response under monochromatic blue light, and the differences were statistically significant (all at P<0.05). The accommodative microfluctuations under red, green, blue, red+ blue, red+ green, blue+ green and white light conditions were (0.142±0.033), (0.128±0.038), (0.131±0.043), (0.139±0.039), (0.127±0.034), (0.131±0.043) and (0.139±0.042)D in emmetropic group, and (0.178±0.043), (0.164±0.043), (0.159±0.039), (0.174±0.042), (0.166±0.036), (0.159±0.031) and (0.174±0.035)D in myopic group, respectively, showing statistically significant differences between them ( Fgroup=12.146, P<0.01; Flight=2.782, P<0.05). The accommodative microfluctuations under the 7 light conditions were higher in myopic group than in emmetropic group, and the differences were statistically significant (all at P<0.05). In myopes, the accommodative microfluctuation was the largest under red light, which was significantly larger than that under blue light, and was the smallest under blue+ green light (all at P<0.05). There was no significant difference in the accommodative microfluctuation between bichromatic light and its two monochromatic lights, or between the polychromatic light (white light) and its three monochromatic lights (all at P>0.05). There was no significant effect of various chromatic lights on the accommodative microfluctuation in emmetropic group (all at P>0.05). Conclusions:The accommodative microfluctuation is greater in myopes than in emmetropes.The stimuli produced by long-wavelength light cause larger accommodative microfluctuation, while conflicting stimuli generated by different chromatic lights do not increase accommodative microfluctuation.

Comparison of stereoacuity in patients of anisometropia, isometropia and emmetropia

Purpose: To compare the stereoacuity in patients with anisometropia, isometropia, and emmetropia. Methods: A cross?sectional study was conducted on 1403 subjects (range: 5–45 years) divided into anisometropes (n = 403), isometropes (n = 500), and emmetropes (n = 500). There were 258 amblyopic eyes among anisometropes and 156 amblyopic eyes among isometropes. Stereoacuity was measured using the Titmus stereo test consisting of a combination of contour targets. Results: There were 675 males and 728 females. A significant (P < 0.001) reduction in stereoacuity was found in anisometropes as compared to isometropes and emmetropes. The stereoacuity was even worse in amblyopes as compared to non?amblyopes. Most patients with anisometropia of <3.0 D had fair stereoacuity. However, as the degree of anisometropia increased to >3.0 D, stereoacuity deteriorated gradually. Marked reduction of stereoacuity was observed in severe degree of anisometropia (>6.0 D). Overall, an anisometropia of ?2.12 D was associated with reduced stereoacuity. Among the anisometropes, it was found to be the poorest in myopia, followed by myopia with astigmatism, hypermetropia with astigmatism, and hypermetropia. Conclusion: The level of stereoacuity was worse in anisometropes as compared to isometropes and emmetropes. Amblyopes had a greater reduction in stereoacuity than non?amblyopes. Stereoacuity decreased as the degree of anisometropia increased. Among the anisometropes, myopes had worst stereoacuity than hypermetropes.

Comparing the vision quality using double-pass technique in eyes with corrected refractive errors and emmetropic eyes / Comparação da qualidade óptica usando a técnica de dupla passagem em olhos com erros de refração corrigidos e olhos emetrópicos

ABSTRACT Purpose: To evaluate the vision quality by measuring the objective light scatter index and objective optical quality parameters (Strehl Ratio and Modulation Transfer Function) in patients with emmetropia and ametropia. Methods: This prospective, cross-sectional study included 408 eyes. The ametropic group comprised of eyes with best-corrected visual acuity of 0.0 logMAR or better and present at least a refractive error of ≥0.25 D. Patients underwent slit lamp examination, visual acuity, refraction, and vision quality using the HD Analyzer. Results: The mean objective light scatter indices were 0.62 ± 0.63, 0.77 ± 0.70, 0.74 ± 0.30, 0.93 ± 0.55, and 0.85 ± 0.61, and mean Strehl Ratio and Modulation Transfer Function scores were 38.17 ± 10.4, 37.37 ± 10.06, 29.84 ± 9.71, 33.2 ± 12.11, and 33.13 ± 10.09 in emmetropes, myopia, hyperopia, spherical equivalent of ≥0, and spherical equivalent of <0, respectively. Differences in all variables were significant between emmetropic and corrected hyperopic and between spherical equivalent of ≥0, and spherical equivalent of <0 eyes (p<0.05). Conclusion: In spectacle-corrected conditions (with trial frames), emmetropic and simple myopic eyes had significantly better vision quality compared to hyperopic and astigmatic eyes. The clinical significance of these results should be investigated in further studies.

RESUMO Objetivo: Avaliar a qualidade óptica medindo o índice de dispersão objetiva de luz e os parâmetros de qualidade óptica objetiva (Razão de Strehl e Função de Transferência de Modulação) em indivíduos com emetropia e ametropia. Métodos: Estudo prospectivo, transversal, incluindo 408 olhos. O grupo ametrópico era de olhos com melhor acuidade visual corrigida de 0,0 logMAR ou melhor e apresentando, pelo menos, um erro refrativo de 0,25 D ou mais. Os pacientes foram submetidos a exame com lâmpada de fenda, acuidade visual, refração e qualidade óptica com o HD Analyzer. Resultados: O índice de dispersão objetiva de luz médio foi de 0,62 ± 0,63, 0,77 ± 0,70, 0,74 ± 0,30, 0,93 ± 0,55, 0,85 ± 0,61 e a média da Razão de Strehl e de Função de Transferência de Modulação foram 38,17 ± 10,4, 37,37 ± 10,06, 29,84 ± 9,71, 33,2 ± 12,11 e 33,13 ± 10,09 em olhos emetrópicos, míopes, hipermétropes, equivalente esférico ≥0 e equivalente esférico <0 respectivamente. Foram encontradas diferenças significativas em todas as variáveis entre olhos emetrópicos e com hipermetropia corrigida, equivalente esférico ≥ 0 e equivalente esférico <0 (p<0,05). Conclusão: Em condições com lentes corrigidas (com armações de prova), os olhos emetrópicos e com miopia simples apresentaram qualidade óptica significativamente melhor em comparação com os olhos hipermétropes e astigmáticos. O significado clínico destes resultados deve ser estudado posteriormente.

Intraocular lens power estimation for future emmetropia in pediatric cataract surgery / Estimativa do poder da lente intraocular para emetropia futura em cirurgias de catarata pediátrica

ABSTRACT Purpose: Creating models, in pediatric cataracts, to estimate kerotometry and axial length values at future ages, based on kerotometry and axial length measured at surgery, to estimate the intraocular lens power for emmetropia in future ages. Methods: Eyes with bilateral cataract and kerotometry and axial length measured at surgery and at least one postoperative examination with kerotometry and axial length measurements, were considered for this study. The models to estimate future kerotometry and axial length values were created considering (1) kerotometry and axial length measured at surgery, (2) the average slope of kerotometry and axial length logarithmic regression created for every single eye and (3) age at surgery. The intraocular lens for future ages can be estimated using these values in third generation formulas. The estimation errors for kerotometry, axial length and intraocular lens were also calculated. Results: A total of 57 eyes from 29 patients met the inclusion criteria. The average age at the surgery and follow-up was 36.96 ± 32.04 months and 2.39 ± 1.46 years, respectively. The average slope of logarithmic regression created for every single eye were -3.286 for kerotometry and +3.189 for axial length. The average absolute estimation errors for kerotometry and axial length were respectively: 0.61 ± 0.54 D and 0.49 ± 0.55 mm, and for intraocular lens using SRK-T, Hoffer-Q and Holladay I formulas were: 2 . 04 ± 1 . 73 D , 2 . 49 ± 2 . 10 D and 2 . 26 ± 1 . 87 D, respectively. Conclusions: The presented models could be used to estimate the intraocular lens power for emmetropia at future ages to guide the choice of the intraocular lens power to be implanted in pediatric cataract.

RESUMO Objetivo: Criar modelos, em catarata pediátrica, para estimar valores futuros de ceratometria e comprimento axial, com base na ceratometria e no comprimento axial medidos na cirurgia, para previsão do poder da lente intraocular para emetropia em idades futuras. Métodos: Olhos com catarata bilateral, ceratometria e comprimento axial medidos na cirurgia e pelo menos um exame pós-operatório com medidas de ceratometria e comprimento axial foram considerados para este estudo. Os modelos para estimar futuras ceratometrias e comprimentos axiais foram criados considerando (1) ceratometria e comprimento axial medidos na cirurgia, (2) a inclinação média da regressão logarítmica da ceratometria e comprimento axial criada para cada olho e (3) a idade na cirurgia. A lente intraocular para emetropia em idades futuras pode ser estimada usando esses valores em fórmulas de terceira geração. Os erros de estimativa da ceratometria, comprimento axial e poder da lente intraocular, usando os modelos, também foram calculados. Resultados: 57 olhos de 29 pacientes preencheram os critérios de inclusão. A idade média na cirurgia e acompanhamento foram de 36,96 ± 32,04 meses e 2,39 ± 1,46 anos, respectivamente. A inclinação média da regressão logarítmica criada para cada olho foi de -3.286 para ceratometria e + 3.189 para o comprimento axial. Os erros médios de estimativa absoluta para ceratometria e comprimento axial foram respectivamente: 0,61 ± 0,54 D e 0,49 ± 0,55 mm, e para o poder da lente intraocular usando as fórmulas SRK-T, Hoffer-Q e Holladay I foram: 2,04 ± 1,73 D, 2,49 ± 2,10 D e 2,26 ± 1,87 D, respectivamente. Conclusões: Os modelos apresentados podem ser utilizados para estimar o poder da lente intraocular que levaria a emetropia em idades futuras e orientar a escolha do poder da lente intraocular a ser implantada na catarata pediátrica.

A Comparative Study of Corneal Endothelial Cell Count and Central Corneal Thickness in Emmetropia and Axial Myopia

The main attributes of cornea which makes it optically important is its ability to maintain its dehydrated state. This corneal dehydration can be achieved and maintained by various factors among which corneal endothelial cell count and morphology play a significant role. Corneal attributes considered in this study i.e. the corneal endothelial cell count and central corneal thickness are extremely variable, and changes are seen even with smaller changes in anterior segment or overall structural changes in eyes. We wanted to compare central corneal thickness in emmetropia and axial myopia and compare corneal endothelial cell count in emmetropia and axial myopia. METHODSThe sample size was decided taking into consideration various prevalence studies. The patients were consecutively recruited for the study considering the inclusion and exclusion criteria. The subjects were divided into two groups emmetropia and axial myopia and were differentiated on the basis of the axial lengths. Specular microscopy was performed for the subjects and corneal endothelial cell count, morphology and central corneal thickness were measured, and comparative study was performed. RESULTSThis study of 80 eyes shows us that the difference between mean the corneal endothelial cell count between emmetrope (2812.80 cells / mm2) and axial myopes (2653 cells / mm2) is statistically significant where p was < 0.05 while the mean central corneal thickness measurements didn’t show statistically significant change between emmetrope (490.05 microns) and axial myope. (489.37 microns). CONCLUSIONSAxial length has an indirect correlation with the corneal endothelial cell count which is statistically significant. While significant correlation between the central corneal thickness and axial length cannot be established in this study.

Clinical Features of Children with +4.00 Diopters or More Hyperopia Weaning with Age

PURPOSE: To evaluate the clinical features of children with high hyperopia weaning with age. METHODS: The medical records of 203 children wearing spectacles due to hyperopia of +4.00 diopters (D) or greater in at least one eye based on the cycloplegic refraction and with follow-up for 3 years or more were reviewed. The patients were divided into those who showed a decrease in the spherical equivalent (SE) of 1.50 D or greater and those who maintained. The age of wearing spectacles, the magnitude of hyperopia, the angle of deviation, the ratio of accommodative-convergence to accommodation (AC/A), and the frequency of amblyopia and anisometropia were compared. RESULTS: Forty seven patients with decreased hyperopia and 156 patients with sustained hyperopia were included. The decreased-group started to wear spectacles later than the sustained-group (5.0 ± 2.3 years vs. 4.1 ± 2.4 years). The mean SE of the hyperopic eye in the decreased-group was significantly greater at the initial visit than in the sustained-group (6.29 ± 2.18 D vs. 5.47 ± 1.38 D); was identical at the 1 year follow-up (4.83 ± 1.72 D vs. 4.89 ± 1.55 D); and significantly lower at the last follow-up (3.15 ± 1.72 D vs. 4.65 ± 1.56 D). In the decreased-group, the mean hyperopia of 3.14 ± 2.02 D decreased during a mean period of 3.9 years, especially during the first year after spectacle correction. At baseline, the frequency and angle of esotropia at both distant and near with/without hyperopic correction was significantly larger in the sustained-group. The frequency of amblyopia and anisometropia and the AC/A were identical between the two groups, while the frequency of amblyopia at the last follow-up was significantly lower in the decreased-group. CONCLUSIONS: Some patients with hyperopia of +4.00 D or greater who had none or a small angle of esotropia and improved amblyopia showed a decrease in hyperopia with age.

Clinical analysis of 426 emmetropia patients with unilateral rhegmatogenous retinal detachment and retinal lesions in the contralateral eyes / 中华眼底病杂志

Objective To observe the fundus lesions in the unilateral rhegmatogenous retinal detachment (RRD) eyes and contralateral eyes in non-traumatic emmetropia patients,and explore the risks of lateral eyes.Methods This is a retrospective case analysis.A total of 426 patients of unilateral RRD diagnosed by clinical examination were enrolled in this study.There were 273 males and 74 females.The average age of onset was 54.7 years.81.46％ of them (347 patients) were 51-70 years old.The average detachment time was 2.12 months.They were divided into two groups,equal or lesser than 50 years old group and more than 50 years old group.A total of 100 patients (200 eyes) with ocular surface disorders were randomly selected as control.The lattice-like degeneration,cystic degeneration and dry retinal holes were treated with prophylactic laser photocoagulation.Follow-up period was 6 to 24 months.The age,gender,proliferative vitreous retinopathy (PVR) grading,best corrected visual acuity (BCVA),distribution and quantity of retinal holes,and posterior vitreous detachment (PVD) were retrospectively analyzed.The incidence of PVD among different age groups was compared with Chi square.Results Among 426 RRD eyes,there were 239 eyes (56.10％) with PVD.Among them,there were 30 eyes with age equal or lesser than 50 years old (12.55％) and 209 eyes with age more than 50 years old (84.75％).There were 187 eyes (43.90％) without PVD,which including 38 eyes with age equal or lesser than 50 years old (20.32％) and 149 eyes with age more than 50 years old (79.68％).The incidence of PVD among different age groups was statistically significant (x2=4.72,P＜ 0.05).There were 10,254,40 and 5 eyes in class A,B,C and D of PVR,respectively;117 eyes without PVR.The retinal hole was located in superior temporal,inferior temporal,superior nasal,inferior nasal and macular in 305,91,22,4 and 4 eyes,respectively.The number of holes was 1,2,and more than 3 in 297,89 and 40 eyes,respectively.The retinal detachment range of 1,2,3 quadrants and total dissociation were 92,230,71,33 eyes,respectively.The fundus lesion was found in 47 eyes (11.03％) in the lateral eyes.There were 20 RRD eyes in class B of PVR,and 27 RRD eyes in class C of PVR.Retinal degenerated area was found.Among them,the degeneration of 41 eyes was located in the temporal retina,45 eyes involved in a quadrant.There were 16 eyes with peripheral retinal dry holes;the holes diameter was less than 1,1-2,greater than 2 optic-discs in 6,11 and 5 retinal holes.At the end of the follow-up,there were 47 eyes with almost normal visual field,16 eyes with decreased visual acuity,noeyes with retinal detachment.In the control group,4 patients (5 eyes,2.50％) had fundus lesions.Conclusion The unilateral RRD in non-traumatic emmetropia mostly occurs in elderly patients;11.03％ of patients had fundus lesions in the contralateral eyes,higher than the general population.

Change of the cornea in emmetropia and myopia in population-based epidemiological studies / 国际眼科杂志(Guoji Yanke Zazhi)

@#Ocular refraction is mainly decided by the axial length, corneal power and lens power. Of these three refractive elements, only the change of cornea has aroused the most controversial discussion. Cornea has changed varying with refractive state and population characteristics. This paper is designed to review the information currently available concerning the change of the cornea in emmetropia and myopia.

Analysis on intraocular pressures and partial biological parameters of emmetropia of Uyghur and Han nationality college students / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To test the intraocular pressures and some biological parameters of Uyghur and Han healthy college students whose eyes are emmetropia, and to conduct comparisons between the two races, two genders, and the right and left eyes whether there is a difference between the two races. ●METHODS:Cross-sectional study. The vision of college students who reach the clinic with visual chart were tested; the keratorefractive power with an automatic refractor was tested; the eyes with slit lamp and ophthalmoscope were tested. The intraocular pressures of 405 cases ( 810 eyes in total ) with an automatic non-contact tonometer were tested; The anterior chamber depths, lens thicknesses, vitreous cavity lengths and axial lengths with an A/B - type ultrasound diagnostic equipment were tested; The intraocular pressures and some biological parameters of the two races, two genders, same genders of different races, and the right and left eyes were compared. ●RESULTS: The differences between Uyghur and Han college students in intraocular pressure, anterior depth, lens thickness, vitreous cavity length and axial length were statistically significant ( P 0. 05 ). The differences between Uyghur male college students and Han male college students in intraocular pressure, anterior depth, vitreous cavity length, axial length and lens thickness were statistically significant (P ● CONCLUSION: Compared with Uyghur college students, Han college students are higher in intraocular pressure, deeper in anterior depth, longer in vitreous cavity length and axial length, and thinner in lens thickness. Compared with female college students of same race, the male college students are longer in axial length and smaller in keratorefractive power. Moreover, Uyghur male college students are deeper than Uyghur female college students in anterior depth. Compared with Uyghur male college students, Han male college students are higher in intraocular pressure, deeper in anterior depth, longer in vitreous cavity length and axial length, and thinner in lens thickness. Compared with Uyghur female college students, Han female college students are higher in intraocular pressure, deeper in anterior depth, and longer in axial length. There is no difference between the right and left eyes.

Association analysis of accommodative microfluctuations and wavefront aberration in emmetropia and myopia in teenagers / 中华实验眼科杂志

Background When focusing on a target,the accommodative system exhibits small variations in power within a range,termed microfluctuations.Exploring the correlation between the characters of microfluctuations and the aberrations of the eyes through a critical period-teenager can deepen the understanding of the onset and development of myopia.Objective This study was to investigate the correlation between accommodative microfluctuations and wavefront aberrations of human eyes,and to explore the role of accommodative microfiuctuations in the development of myopia.Methods A cross-sectional study was designed and performed.Fifty-four teenagers aged from 12 to 15 years were enrolled in this study in Eye Hospital,Wenzhou Medical University from 2010 to 2011,including 19 emmetropic subjects,18 incipient myopic subjects and 17 progressive myopic subjects,who were chosen based on the refractive changes for the last two years.The accommodative response and microfluctuations were measured by WAM-5500 infrared autorefractor with RSVP at 25,33 and 50 cm respectively,each RSVP distance was tested for 5 minutes.The accommodative values were divided into low frequency component (LFC) (0-0.6 Hz),middle frequency component(MFC) (0.6-0.9 Hz) and high frequency component (HFC) (1.0-1.4 Hz) after Fourier spectrum analysis.The wavefront aberrations of the whole eye and corneal were recorded by i-Trace aberrometer and Humphrey corneal topography.The differences of accommodative response,microfluctuations and aberrations were evaluated and compared among the emmetropic group,incipient myopic group and progressive myopic group.The correlations of accommodation and aberrations were analyzed.This study followed Declaration of Helsinki,and informed consent was obtained from each subject.Results Under the 25 cm and 33 cm reading distance,the accommodative response values were (2.78 ± 0.35) D and (2.19 ± 0.27) D in the emmetropic group,which were significantly higher than (2.44±0.33) D and (1.89±0.35)D in the progressive myopic group (P=0.002,0.003).LFC,MFC and HFC were remarkably increased as the reading distance decreased (Fdistance =8.480,14.270,21.400;all at P ＜0.01).A significant difference was seen in LFC among different reading distances (Fgroup =4.115,P＜0.05),and the LFCs in the progressive myopic group were considerably higher than those in the emmetropic group in the 25,33 and 50 cm reading distances (P=0.044,0.038,0.032).No significant differences were found in MFC and HFC among the three groups (Fgroup =0.859,0.682;both at P＞0.05).Under the 25 cm and 33 cm reading distances,significant positive correlations were found between LFC and corneal coma,intraocular coma,whole ocular aberrations or intraocular higher order aberrations (all at P＜0.05),however,no significant correlations were seen between MFC or HFC and wavefront aberrations (all at P＞0.05).Conclusions In teenagers,the accommodative response of emmetropia is much stronger than that of progressive myopia,and the accommodative microfluctuation in emmetropia and incipient myopia is much less than that in progressive myopia.These shifts are possibly associated with the variability,and microfluctuations of accommodation is greater in progressive myopes than emmetropes.There are certain correlations between wavefront aberrations and accommodative microfluctuations.The refractive group differences in the accommodative microfluctuations may be related to differences in the wavefront between myopes and emmetropes.Under near reading distance,LFC is correlated with higher order aberrations.

Influences of prisms on accommodative response and microfluctuation in emmetropias / 中华实验眼科杂志

Background How to control progression of myopia is a central issue in clinical optometry.Some clinical trials showed that wearing base-in (BI) prism can slow down progression of myopia to certain degree.However,whether BI prism or base-out (BO) prism should be used is worth discussing.Objective This study was to investigate the influences of different prisms on accommodative response and microfluctuation in emmetropias.Methods This clinical trail was approved by Ethic Committee of Peking University People's Hospital.During July in 2014,twenty-two emmetropias of 22 normal volunteers aged 21-27 years were recruited from Peking University People's Hospital under the written informed consent.An open-field infrared refractometer was used to monitor and record pupil diameter and accommodative response under three conditions including non-prism,3△ BI prism,and 3△ BO prism.The accommodative response value was calculated as the difference between reading value and-3.0 D,and root mean square (RMS) of accommodative response value served as amplitude of accommodative microfluctuation.Spectrum of accommodative response was analyzed by one dimension discrete Fourier transformation.The differences of accommodative response value,amplitude of accommodative microfluctuation and pupil diameter among three conditions were compared using repeated one-way ANOVA.Results The accommodative response values were (+0.31±0.78),(+0.51±0.75) and (+0.18±0.72) D under the non-prism,3△BI prism and 3△BO prismconditions,respectively,with a significant difference among them (F =28.078,P =0.000),and compared with the non-prism condition,the accommodative lag of 3△BI prism condition was increased and that of 3△BO prism condition was reduced (P =0.000,0.012).No significant difference was found in the amplitude of accommodative microfluctuation among the three conditions (F=0.062,P =0.879).The percentages of low frequency signal power (0-0.5 Hz)/total power (0-2.5 Hz) was 97.5％,98.3％ and 91.4％ under the non-prism,3△BI prism and 3△BO prism condition,respectively.The pupil diameter was (5.37-±0.69) mm under the 3 △ BI prism condition,which was larger than (5.07±0.66) mm under the non-prism condition and (5.01 ±0.69) mm under the 3△ BO prism condition (both at P =0.000).Conclusions Compared with wearing 3△ BI prism,wearing 3△ BO prism lessens the accommodative lag,decreases the pupil diameter and reduces the power of low frequency component in accommodative response.

A novel concept of accommodation:Human eyes optical system based on hyperfocal distance-micro zoom / 中华实验眼科杂志

Based on a concept of the hyperfocal distance from photographic lens,this study proposes that emmetropia presents far-hyperfocal distance,near-hyperfocal distance and accommodative hyperfocal distance.When emmetropic presbyopias completely lose the ability of accommodation,its farthest blur point is not beyond 1.5 m,even not being at infinity,and the phenomenon of dark focus both completely match with the definition of hyperfocal distance.On the other hand,after cycloplegic mydriatics in emmetropia,it could be found in the region of depth-of-field that there is no change in the back depth of field (clearness in far vision),but change was found in the front depth of field (blur in near vision).It conforms well to the definition of the hyperfocal distance,demonstrating that human eyes belong to the hyperfocal distance optical system.Furthermore,it is reported that the emmetropic presbyopias rarely matched the spectacles higher than +2.50 D in their whole life;therefore,it can be inferred that their accommodative amplitude in youth is equal to this corrected value.This value accounts for about 4％ of the total refractive power in human eyes,so it is suggested that human eye is a micro zoom optical system.Based on the objective existence of hyperfocal distance,the author proposes that human eye is an integrated accommodative mechanism.It includes three components:the accommodative mechanism of near vision,the measuring and controlling mechanism of near vision,and the general control of near vision.This paper discusses the accommodative mechanism of near vision and the resting mechanism of distance vision based on the hyperfocal distance,and considers that when human eye transfer into the accommodation of near vision from the normal distance vision of hyperfocal distance.There are three different pushing forces contributing to lens deformation and its anterior shift,and these forces cause four different accommodative efforts,which constitute the real accommodative efforts in the relative tissue.This paper also points out that it is only the mode of pushing accommodation that can make the lens vary refraction quickly and greatly,and control the amount of deformation effectively.That can not be achieved by the stretching mode proposed by Tscherning & Schachar,because some authors have verified that excessive pulling would result in decline in the refraction,which would be difficult to regulate and control the eye.Similarly,the self-bulging mode of Helmholtz & Gullstrand will not work neither,because it is unable to control the amount of lens deformation that is its fatal defect.

Astigmatismo miópico posterior al LASIK en pacientes operados en el Centro Oftalmológico "Enrique Cabrera" de La Habana / Myopic astigmatism after LASIK in patients operated at "Enrique Cabrera" Ophthalmology Center from Havana

Se efectuó un estudio descriptivo, longitudinal y retrospectivo de los 264 pacientes operados de astigmatismo miópico mediante LASIK en el Centro Oftalmológico del Hospital General Docente "Enrique Cabrera" de La Habana, durante el 2009, con vistas a caracterizarles luego del tratamiento quirúrgico. En la casuística primaron el sexo femenino (61,7 %) y el grupo etario de 20-30 años (41,3 %), así como la agudeza visual preoperatoria de cuenta dedos a 0,2 (62,8 %) y la posoperatoria de 0,6 a 1,0 (98,1 %). Después de aplicada la terapéutica, la esfera disminuyó en 95,0 % de los integrantes de la serie a valores entre 0,00 y -1,00 dioptrías y el cilindro, en 98,7 %, con medidas inferiores a -1,50 dioptrías. Los valores queratométricos de 41,25 a 43,00 dioptrías estuvieron presentes en 72,1 % de los afectados y el equivalente esférico mostró un acercamiento sustancial a la emetropía en 82,3 % de las intervenciones, con un intervalo entre -1,00 y 0,00 dioptrías.

A descriptive, longitudinal and retrospective study was carried out in 264 patients operated on myopic astigmatism by means of LASIK at "Enrique Cabrera" General Teaching Hospital from Havana, during 2009, in order to characterize them after surgical treatment. Female sex (61.7%) and age group between 20 and 30 years (41.3%) prevailed in the case material, as well as preoperative and postoperative visual acuity of counting fingers of 0.2 (62.8%) and 0.6 to 1.0 (98.1%) respectively. After the treatment have been applied, in 95.0% of patients from the series the sphere decreased to values between 0.00 and -1.00 diopters, and the cylinder, in 98.7%, measuring less than -1.50 diopters. Keratometric values from 41.25 to 43.00 diopters were present in 72.1% of those affected and the spherical equivalent showed a substantial approach to emmetropia in 82.3% of the surgeries, with a range between -1,00 and 0,00 diopters.

Ocular Biometric Measurements In Emmetropic And Myopic Malaysian Children - A Population-Based Study

This is the first population based study on ocular biometric measurements (OBMs) conducted in Malaysia. Its objective is to measure and compare among children of different ethnicity who have myopia and emmetropia. Subsets of children aged between 7 and 8 years old who participated in a larger population based refractive error study had their axial length, anterior chamber depth, lens thickness and vitreous depth measured using A scan and vertical and horizontal corneal curvature measured using an autokeratorefractometer. Eighty eight of the 870 children (10.1%) examined had myopia. Boys, Chinese and children with myopia had significantly longer axial length and vitreous depth compared to girls, Malay and Indian and children who were emmetropic respectively. Girls and children with myopia had steeper corneal curvature. The baseline OBMs in Malaysian children of different ethnicity are valuable for studies in myopia progression. Like other studies, children with myopia have longer axial length (P <0.001). and vitreous depth (P <0.001) compared to children who are emmetropia (without myopia).

Macular Thickness Changes with Age and Gender in Emmetropia Using Spectral Domain Optical Coherence Tomography

PURPOSE: To evaluate the changes in macular thickness with regard to age and gender in normal subjects with emmetropia using spectral domain optical coherence tomography. METHODS: The present study consisted of 90 healthy subjects (162 eyes) with no ophthalmic evidence of retinopathy and who had emmetropic eyes. The data from macular measurements using spectral domain optical coherence tomography was analyzed according to the groups divided by age (Group 1: 0 to 19 years of age, Group 2: 20 to 39 years of age, Group 3: 40 to 59 years of age, Group 4: 60 to 80 years of age) and gender. RESULTS: Macular thickness of the central circle was 253.40 +/- 23.03 microm in all subjects. There was no significant change with age (p > 0.05). However, the measurements at the inner (3 mm) and outer circle (6 mm) showed a reduction of macular thickness with age (p < 0.05). The macular thickness at the central and inner circle was significantly lower in the female subjects (p < 0.05). In group 3 and 4, macular thickness at the central circle in males was greater than in females. In group 3, the average inner macular thickness in males was significantly greater than in females (p < 0.05). CONCLUSIONS: In normal subjects with emmetropia, there are statistically significant differences in macular thickness between subjects of different age and gender. The results from the present study can be expected to provide a reference value for evaluating macular disease.

Change in Ocular Dimensions with Age in Patients with Emmetropia

PURPOSE: We evaluated changes in ocular dimensions according to age in patients with emmetropia. METHODS: We examined the refraction, corneal curvature, and biometry in 150 subjects from 5 to 75 years old with spherical equivalent refractions under +/-0.75 diopter (D). Ocular dimensions were measured by A-scan ultrasonography and keratometry. We analysed the distribution and change of ocular dimensions according to age (1: 0~19-year-old group, 2: 20~39-year-old group, 3: 40~59-year-old group, 4: 60~79-year-old group). RESULTS: The values for corneal radius (CR), vitreous chamber depth (VCD) and axial length (AL) were highest in group 2. Lens thickness (LT) increased with increasing age, whereas anterior chamber depth (ACD)decreased with increasing age (P<0.05). CR, VCD, AL (P<0.05) and ACD (P=0.10) seem to have higher values in males, while LT seems to have a higher value in females (P=0.06). CONCLUSIONS: Axial length increases with increasing age in subjects aged 0 to 39 years in emmetropia. In subjects aged 40 years or older, axial length becomes smaller with age. In each age group compensational changes to achieve emmetropia according to AL change are shown in ocular dimensions like CR, VCD, ACD, LT.

Distribution and Change of Total Astigmatism, Corneal Astigmatism and Residual Astigmatism with Age in Patient with Emmetropia

PURPOSE: We evaluated the distribution and change of total, corneal and residual astigmatism with age in patients with emmetropia. METHODS: We examined the visual acuity, refraction, and corneal curvature in 263 persons aged from 3 to 83 years (mean, 38 years), with a spherical equivalent refraction of under +/-0.75 diopter (D). We analysed the distribution and change of the astigmatism. RESULTS: Total astigmatism was changed from with-the-rule (WTR) to against-the-rule (ATR) with aging based on WTR of 0.31 +/- 0.48 D in the 3-10 year-old group, ATR of 0.02 +/-0.52 D in the 31-40 year-old group and ATR of 0.65 +/- 0.66 D in the 71-83 year-old group. Corneal astigmatism showed a similar pattern to that of total astigmatism with WTR of 1.03 +/- 0.47 D, WTR of 0.37 +/- 0.78 D, ATR of 0.05 +/- 0.59 D and ATR of 0.31 +/- 0.64 D in the 3-10, 31-40, 61-70 and 71-83 year-old groups, respectively. Residual astigmatism showed ATR astigmatism in all age groups such as ATR of 0.71 +/- 0.48 D, ATR of 0.60 +/- 0.44 D and ATR of 0.35 +/- 0.71 D in the 3-10, 41-50 and 71-83 year-old groups, respectively. CONCLUSIONS: Total and corneal astigmatism showed the change from WTR to ATR, and residual astigmatism showed the pattern of decreasing ATR with aging in patients with emmetropia. The change of total astigmatism with aging seems to be influenced by that of corneal astigmatism rather than by that of residual astigmatism.

A Study on the Heterophoria in Emmetropia and Ametropia

The purpose of this study was to examine the heterophoria in emmetropia and ametropia. The subjects were 337 healthy men and women between the age of 20-41 years. In 337 cases, Emmetropia were 135 cases, Ametropia were 202 cases. The entire group was tested for heterophoria with synoptophore. In the ametropia, this test was performed before and after correction of refractive error with glasses. The results were as follows: 1. The incidence of heterophoria was 84.4% in emmertropia, 89.2% in myopia and 91.4% in hyperopia. 2. Exophoria was most common in myopia. But in emmetropia and hyperopia, there was no significant difference between the incidence of exophoria and esophoria. The incidence of hyperphoria and cyclophoria was not significantly different between emmetropia and ametropia. 3. In the ametropia, the size of heterophoria was slightly decreased after correction, but the difference was not significant (p>0.05). 4. There was no correlation between the amount of refractive error and the size of heterophoria (p>0.05).