Based on the Gullstrand I model eye, a simplified model eye for testing fundus imaging device is designed. The model eye can reach the following requirements:(1) The refractive characteristics of the ocular refractive tissue are simulated, and the equivalent focal length in air is 17 mm; (2) The differences between relative refractive index differences of the adjacent materials of the simplified model eye and relative refractive index differences of any adjacent two layers (cornea and aqueous humor, aqueous humor and lens, lens and vitreous body) of the Gullstrand I model eye are not more than 1%; (3) In the case of the incident aperture diameter of 3 mm, the differences of radii of the diffuse spots formed by the paraxial light and the axial light are not more than 15%; (4) The differences of angles of chief ray and tangent line of the fundus are not more than 1°; (5) In the case of the incident aperture diameter of 3 mm, the differences of MTF values of the near axis light are not more than 0.1. The simplified model eye can be expected to be used for testing fundus imaging device instead of the test method in ISO 10940:2009 Ophthalmic instruments-Fundus cameras.
Cornea ; Fundus Oculi ; Lens, Crystalline ; diagnostic imaging ; Refraction, Ocular

INTRODUCTIONMyopes are suspected to be poorer at responding to accommodative stimuli than emmetropes, and this may worsen the degree of their myopia. The study aims to compare the abilities of young adult emmetropes and myopes in responding to accommodative stimuli, as indicated by their Accommodation Stimulus Response Curves (ASRCs) in a predominantly Chinese population.

MATERIALS AND METHODSSeventeen emmetropes and 33 myopes aged between 16 and 23 years (mean, 18.6 +/- 1.2) were recruited, of whom 11 were progressing and 22 were non-progressing myopes. The ASRC gradients of subjects were measured using the methods of decreasing distance series (DDS), positive (PLS) and negative lens series (NLS).

RESULTSThe ASRC is method dependent. The gradients of the curves are significantly different among 3 methods of measurement using single-factor ANOVA (F3.057 = 44.815, P <0.01). The slopes of the accommodative errors of all subjects were steeper using the NLS method, and the lags of accommodation increased with elevated demands. No significant differences in ASRC gradients were found between emmetropes, non-progressing myopes and progressing myopes for the range of accommodative demands for each method. Progressing myopes showed the highest error towards the higher demand compared with the emmetropes and non-progressing myopes.

CONCLUSIONAccommodative responses of myopes were more sluggish though there were no statistical differences in ASRC gradients between emmetropes and myopes. It is not certain if the poorer accommodative responses were a cause, or a consequence, of myopia.

Accommodation, Ocular ; Adolescent ; Adult ; Disease Progression ; Female ; Humans ; Male ; Myopia ; physiopathology ; Refraction, Ocular

OBJECTIVETo observe therapeutic effect of electrical plum-blossom needle for treatment of juvenile myopia and biological effect on ocular tissue and structures.

METHODSOne hundred and sixty cases with mild myopia (diopter < 3.00D) were randomly divided into two groups, a treatment group and a control group. The treatment group were treated with electrical plum-blossom needle therapy, tapping Jingming (BL 1), Chengqi (ST 1), Taiyang (EX-HN 5) and Neiguan (PC 6), and the control group with Tropicamide eye drops. The changes of vision, diopter, corneal refractive power, ocular-axial length, lens and ciliaris thickness were observed before and after treatment.

RESULTSThe total effective rate was 80.0% in the treatment group and 58.1% in the control group, with a very significant difference between the two groups (P < 0.01); the two therapies could decrease the thickness of lens and ciliaris, and eliminate spasm of ciliary muscle, however the electrical plum-blossom needle therapy had more obvious action (P < 0.05); the two therapies had no effect on the corneal refractive power and ocular-axial length.

CONCLUSIONThe electrical plum-blossom needle therapy is an effective method for increasing vision, correcting ametropia and delaying development of myopia.

Adolescent ; Child ; Electroacupuncture ; methods ; Female ; Humans ; Male ; Myopia ; physiopathology ; therapy ; Refraction, Ocular ; Vision, Ocular

OBJECTIVETo test the effects of corrective spectacles in hyperopic amblyopic children with heterophoria.

METHODSVisual acuity, refraction and the amount of heterophoria on near (33 cm) fixation were measured before and after 3 weeks of spectacle-wearing in 30 hyperopic amblyopic children with heterophoria. The control group consisted of 20 emmetropic children age-matched to the patients.

RESULTSUncorrected eyes displayed hyperopic amblyopia accompanied by heterophoria. Corrective spectacles not only attenuated the hyperopia and amblyopia, but also changed the heterophoria to orthophoria. The amount of heterophoria before wearing spectacles was significantly different from that in emmetropic children; but after correction with spectacles, it was the same as that in the emmetropic controls.

CONCLUSIONCorrection with spectacles is effective for the treatment of heterophoria in hyperopic children with amblyopia.

Accommodation, Ocular ; Amblyopia ; diagnosis ; therapy ; Child ; Eyeglasses ; Humans ; Hyperopia ; diagnosis ; therapy ; Refraction, Ocular ; Vision Tests ; methods

A vernier optometer, based on the Scheiner principle, that makes use of polarized light, is designed and developed. It is specialized in measurement of tonic accommodation, accommodation and accommodation response. The vernier optometer has been proved by chinical testing results, to be a reliable and effective instrument with fine stabilily, good repeatability and sensitivity for short sight study relating to oculogyral parameters.
Accommodation, Ocular ; Adult ; Diagnostic Techniques, Ophthalmological ; instrumentation ; Equipment Design ; Humans ; Myopia ; diagnosis ; Optometry ; instrumentation ; Refraction, Ocular ; Reproducibility of Results ; Visual Acuity

BACKGROUNDLaser in situ keratomileusis (LASIK) has become an efficient and commonly performed procedure to reduce refractive errors. In order to further increase the postoperative visual quality, the wavefront-guided refractive surgery has been a research hotspot in customized surgery. This study was conducted to compare the visual acuity, higher-order aberration, and contrast sensitivity of wavefront-guided LASIK with iris-registration and conventional LASIK.

METHODSTwo hundred and eleven myopic eyes of 109 patients were enrolled in this prospective study and randomly divided into two groups: the wavefront-guided LASIK (wg LASIK) group (94 eyes) and conventional LASIK group (117 eyes). A Wavescan Wavefront aberrometer was used to analyze Zernike coefficients and the root-mean-square (RMS) of higher order aberrations with 6.0 mm pupil size, and Optec 6500 visual function instrument was used to measure contrast sensitivity (CS) under 5 spatial frequencies before and after surgery in both groups.

RESULTSThe uncorrected visual acuity (UCVA) and the mean spherical equivalent (SE) in wg LASIK group were significantly better than those in conventional LASIK (UCVA, z = 2.339, P = 0.019; SE, t = 2.838, P = 0.005) at 3 months after surgery. Moreover, the increase in Z(3)(-3), Z(3)(1), Z(3)(3), Z(4)(0), Z(5)(-1), Z(5)(1), Z(5)(5) and Z(6)(-6) in wg LASIK group was statistically smaller than that in conventional LASIK group (P < 0.05). In wg LASIK group, eyes with a higher amount of the preoperative RMS of the higher order aberrations (RMSh = 0.30 microm) showed a statistically lower increase (13.5%) than those in conventional LASIK group at 3 months after surgery (33.3%) (P = 0.004). And the values of 4th order spherical aberration (4thSA) and the root mean square of 6th order aberration (RMS6) in wg LASIK group were significantly lower than those in conventional group in eyes which had higher preoperative astigmatism (= 1.0D) (4thSA, P = 0.03; RMS6, P = 0.02). Wg LASIK group showed better CS values than the correspondingly preoperative values at all spatial frequencies with and without glare at 3 months after the surgery while conventional LASIK group displayed reduced CS values except for 1.5 and 3 cycles per degree with glare. The differences between the two groups were statistically significant (P < 0.001).

CONCLUSIONSWavefront-guided LASIK with iris-registration is efficient to reduce higher order aberrations especially spherical and coma aberrations, and to improve postoperative visual acuity and contrast sensitivity compared with conventional LASIK. The application of wavefront-guided LASIK with iris-registration is particularly suitable for eyes with higher preoperative RMSh values and eyes with higher preoperative astigmatism.

Contrast Sensitivity ; Humans ; Iris ; cytology ; Keratomileusis, Laser In Situ ; methods ; Refraction, Ocular ; Visual Acuity

Rigid contact lenses with eccentricity through manufacture can more or less influence visual correction or induce the corneal warpage. Therefore the fine detection of rigid contact lens eccentricity is needed and important. This study was aimed to design a system for lens eccentricity measurement by the principle of optical reflection. By using a standard concave mirror in the center of lens jig, the geometrical center of a lens could be detected accurately. It has solved the problem of lens distortion and breakableness attributed to the conventional method based on rotating reflection. The system is proved to be of practical method with good repeatability.
Contact Lenses ; adverse effects ; Cornea ; pathology ; Refraction, Ocular ; physiology ; Refractive Errors ; pathology

OBJECTIVETo study the influence of near-work and outdoor activities on myopia progression in school children.

METHODSEighty 7-11-year-old school children with myopia were randomly assigned into an intervention group (n=41) and a control group (n=39). The children in the intervention group did near- and middle-vision activities less than 30 hrs per week and more outdoor activities than 14-15 hrs per week. Myopia progression was observed regularly over 2 years after which ophthalmologists administered questionnaires regarding near-vision work (reading, writing and using computer), middle-vision work (watching TV and extracurricular learning activities), outdoor activities, using nature light, wearing glasses, etc.

RESULTSThe annual mean myopia progression (0.38 ± 0.15 D) in the intervention group was significantly lower than that in the control group (0.52 ± 0.19 D; P<0.01). The children in the two groups spent similar amounts of time in near-vision activities, but the children in the intervention group spent less time in middle-vision activities (P<0.01) and more outdoor activities (13.7 ± 2.4 vs 6.2 ± 1.6 hrs/wk; P<0.01). When considering all children in the study, there were 4 factors that significantly correlated with less myopia progression: more outdoor activities, more time spent wearing glasses, more time spent in natural light and less time using a computer. When analyzing the intervention group separately, more outdoor activity was inversely correlated with myopia progression (t=-2.510, P<0.05). Separate analysis of the control group indicated that more time wearing glasses was correlated with less myopia progression (t=-3.115, P<0.05).

CONCLUSIONSMyopia progression in school children may be slowed by more outdoor activities, more time spent in natural light and more time wearing corrective glasses.

Child ; Disease Progression ; Female ; Humans ; Leisure Activities ; Male ; Myopia ; etiology ; Refraction, Ocular ; Surveys and Questionnaires

BACKGROUNDOptical Quality Analysis System II (OQAS, Visiometrics, Terrassa, Spain) that uses double-pass (DP) technique is the only commercially available device that allows objective measurement of ocular retinal image quality. This study aimed to evaluate the impact of spectacle lenses on the ocular optical quality parameters and the validity of the optometer within OQAS.

METHODSSeventy eyes of healthy volunteers were enrolled. Optical quality measurements were performed using OQAS with an artificial pupil diameter of 4.0 mm. Three consecutive measurements were obtained from spectacle correction corresponding to subjective refraction and from the OQAS built-in optometer separately. The modulation transfer function cutoff frequency, the Strehl ratio, the width of the point spread function (PSF) at 10% of its maximal height (PSF10), and the width of the PSF at 50% of its maximal height (PSF50) were analyzed.

RESULTSThere was no significant difference in any of the parameters between the spectacle correction and the optometer correction (all P > 0.05, paired t-test). A good agreement was found between both the methods and a good intraobserver repeatability in both the correction methods. Difference in best focus between two methods was the only parameter associated significantly with optical quality parameter differences. Best focus difference, built-in optometer correction with or without external cylindrical lens, and age were associated significantly with PSF10 difference. No linear correlation between refractive status and optical quality measurement difference was observed. A hyperopic bias (best focus difference of (0.50 ± 0.44) D) and a relatively better optical quality using spectacle correction in high myopia group were found.

CONCLUSIONSOQAS based on DP system is a clinically reliable instrument. In patients with high myopia, measurements using built-in optometer correction should be considered and interpreted with caution.

Adolescent ; Adult ; Aged ; Female ; Humans ; Male ; Middle Aged ; Refraction, Ocular ; Visual Acuity ; physiology ; Young Adult

OBJECTIVEDesign a convenient and stable eye refractometer based on the theory of blur circle.

METHODSAnalyze the retinal blur circle in both Emsly reduced eye model and Liou & Brennan 1997 eye model by ZEMAX. Design the coefficients including PD (pupil diameter) and NO' (length between node point and fovea) with the purpose of improving the accuracy. At last, compare the clinical optometry data from this refractor with the data obtained from optometry hospital in Wenzhou.

RESULTSThe blur circle diameters are nearly the same in both reduced eye model and the Liou & Brennan 1997 eye model. With the PD = 4 mm and NO' = 20 mm, the refractor shows a fine accuracy in optometry. The paired t test shows that the myopia group and the astigmatism axial direction group have no statistical difference between the data from the blur circle refractor and the hospital (P > 0.05), while the astigmatism degree group has the result of P = 0.41 which may be caused by the poor cooperation of pediatric patients. 80% of the astigmatism degree data differ from the data from the hospital in less than 0.75D.

CONCLUSIONThe blur circle refractor, with the features of convenience and fine accuracy, is promised to be a new style of refractometer in the future.

Astigmatism ; Equipment Design ; Fovea Centralis ; Humans ; Models, Statistical ; Myopia ; Ophthalmoscopes ; Ophthalmoscopy ; Refraction, Ocular ; Visual Acuity