Chinese Journal of Optometry Ophthalmology and Visual science

Objective To study the effect of reading distances on the axis and degree of astigmatism.Methods Twenty-five children (50 eyes) with astigmatism greater than 0.50 D were investigated in a cross-sectional study.The children were between 5～7 years of age.They were given corrective glasses based on the results of optometric tests using 1％ atropine.An infrared autorefractor was used to measure the axis and degree of astigmatism for far (5 m) and near (33 cm) reading distances with full-correction spectacles.A t-test and correlation analysis were used for analysis.Results Changes in the degree of astigmatism were 0.35±0.82 D (t=-3.004,P＜0.01) on average for the near reading distance and the change in the extent of the degree of astigmatism showed no correlation with the degree of astigmatism.62％ (31 eyes) had with-the-rule astigmatism with an axis of 1°～57° on average (17±13)° rocating for near reading distances,while 38％ (19 eyes) had against-the-rule astigmatism with an axis of 1°～52° on average (15±14)°.The change in the axis of astigmatism had no correlation with the degree of astigmatism.Conclusion The degree and axis of astigmatism changes with different reading distances in children so we need to think about the change in the axis of astigmatism when prescribing glasses for children.

Objective To analyze the relationship between the changes in refractive error with and without cycloplegia and oculomotor functions in schoolchildren 6～15 years of age.Methods One hundred fifty eyes of 75 young patients were included in this cross-sectional study.Refractive error was measured with a phoropter before and after cycloplegia induced with the compound tropicamide.Negative relative accommodation (NRA),positive relative accommodation (PRA),BCC and AC/A were measured with a phoropter before cycloplegia.Children were grouped according to changes in their refractive error with and without cycloplegia:a change in sphere or cylinder not less than 0.5 D was the changed group,28 children (56 eyes); a change in sphere or cylinder not more than 0.25 D was the no change group,46 children (92 eyes).A Mann-Whitney U test,x2 test,Spearman correlation analysis and independent t test were used to analyze the data.Results Noncycloplegic measurements of spheres were consistently more negative in the no change group with a median of-2.50 D than in the changed group,-1.75 D (Z=-3.328,P＜0.01).The mean NRAs were 2.27±0.33 D and 1.72±0.48 D in the no change group and changed group,respectively.There was a statistically significant difference between the two groups (t=-5.409,P＜0.01).The mean BCCs were 0.31±0.46 D and-0.09±0.60 D in the no change group and changed group,respectively (t=-3.295,P＜0.01).The mean PRAs were-1.63±0.76 D and-2.14±1.35 D in the no change group and changed group,respectively.Although there was no statistically significant difference between the two groups,PRA was larger in the changed group than in the no change group.There were no statistically significant differences for age,sex,cylinders or AC/A between the two groups.The changes in equivalent spheres before and after cycloplegia were smaller with an increase in NRA (r=-0.393,P＜0.01).Conclusion The changes in refractive error with and without cycloplegia were not correlated with age,sex,cylinders or AC/A in schoolchildren 6～15 years of age.However,it is negatively correlated with NRA.

Objective To compare visual field width when reading with single vision lenses (SVLs),traditional progressive addition lenses (PALs) and double-surface PALs.Methods It was a cross-sectional study.Thirty-two presbyopic subjects were selected randomly from the Eye Hospital of Wenzhou Medical College,from September 2009 to February 2010.Eighteen males and 14 females aged from 46 to 69 years (average 57.9±7.7 years) with add powers from +1.25 to +2.50 D (average +1.97±0.34 D) participated in the study.Using a single-blind trial,the same subject was tested with SVLs,traditional PALs (Varilux comfort PALs,Essilor,France) and double-surface PALs (HOYALUX FD double surface PAL,HOYA,Japan).The width of the visual field was measured while reading at a distance of 40 cm with the different lenses.A one-way ANOVA was used to calculate the data.Results While reading at 40 cm,the width of the visual field was widest with SVLs (about 24.50 cm),and was smallest with traditional PALs (about 18.00±4.27 cm,range 7.50～24.50 cm),and with double-surface PALs it was 21.04±3.62 cm,range 12.40～24.50 cm.The differences between the 3 groups was significant (F=32.40,P＜0.01).The difference between every two lenses were significant (P＜0.01).Conclusion This study proved that compared with SVLs,PALs provide a narrower visual field width when reading.With the improvement in the design of PALs,its visual field width at near has been improved greatly.The double-surface PALs have a wider visual field when reading,and at the same time these lenses reduce the burden of the eye rotating up and down.A wider visual field provides readers with the benefits of good wearing comfort and performance.

Objective To investigate the status and the leading causes of visual disability in patients identified in Tianjin,China.Methods In an investigative study in Tianjin,a total of 15834 patients with visual disability were enrolled from January 2006 to December 2010.Personal statistics,visual function examination results and main etiology diagnoses were recorded.The grading was confirmed according to the 2nd National Sample Survey of Disability.A chi-square test was used to investigate the different leading causes.Results Male patients,urban district residents,older age groups,lower education and lower income accounted for a large part of the patient population.Among the 15834 patients,6598(41.67％) were blind and 9236(58.33％) had low vision.The principal cause is still cataract (32.82％).In addition,the main causes of blindness and low vision were different (x2=38.33,P＜0.01).Blindness resulted primarily from retinopathy/ choroidopathy (15.40％) and corneal disease (13.78％) and low vision resulted primarily from ammetropia/ amblyopia (18.32％) and retinopathy/choroidopathy (17.37％).Conclusion There were a greater number of low vision cases than blindness.Cataract is still the principal cause of visual disability.Better allocation of services and resources is urgently needed.Attention should be given to the rehabilitation of visual disability and great effort should be made to prevent uncorrected visual impairment.

Objective To compare the higher order aberration of polychromatic light between blue light filtering intraocular lenses (IOLs) and transparent IOLs.Methods In an experimental study,blue light filtering IOLs (SN60AT,+20D) and transparent IOLs (SA60AT,+20D) were studied in the schematic eye.The images of the Hartmann-Shark for 3 different wavelengths were processed by a charge-coupled device (CCD) and analyzed in Matlab software.The Zernik polynomial,modulation transfer function (MTF) and point spread function (PSF) curve of the optical path were processed to evaluate the higher order aberrations of the polychromatic light with the two kinds of IOLs.Results The MTF curve of the SN60AT IOLs was low at all frequencies using a 486nm wave-light.The SN60AT IOLs had less higher order aberration,especially spherical aberration,for polychromatic light than the SA60AT IOLs as illustrated by PSF curves.Conclusion The blue light filtering IOL (SN60AT) had less higher order aberration of polychromatic light than the transparent IOL (SA60AT),especially in spherical aberration.

Objective To evaluate a color contrast sensitivity test as a tool for the diagnosis of primary open angle glaucoma.Methods In a prospective case control study,82 eyes suspected of having primary open angle glaucoma served as the SOAG group; 80 primary open angle glaucoma eyes served as the POAG group; 75 normal eyes served as the control group.Color contrast sensitivity was measured with a Chroma Test.The SOAG group was followed up in 6 months.The thresholds of color contrast sensitivity were compared and the differences between and within the groups were statistically analyzed with a one-way ANOVA.In the SOAG group,the thresholds before and after six months were statistically analyzed with a paired t test.The consistency between the two methods was statistically analyzed with Kappa.Results ①The thresholds from high to low were compared for the POAG group,SOAG group and control group.There were significant differences between the POAG group and the control group (P＜0.01) in the protan and tritan axes.There was a significant difference in the lower temporal field and lower nasal field between the POAG group and the SOAG group.There were also significant differences in the upper temporal field,lower temporal field and upper nasal field between the SOAG group and the control group (P＜0.05).②During the 6 months of follow-up for the SOAG group,the threshold was higher comparing to the initial follow-up and there was a significant difference between the upper and lower temporal fields in the tritan axis (P＜0.05).The consistency between the two methods was good (Kappa=0.47).Conclusion Color contrast tests reveal a sensitivity to color change in the early stages of glaucoma.There was a good consistency between the visual field test and the chromatic test.Color contrast can be used in a screening program and to monitor patients who develop glaucoma.

Objective To evaluate the accuracy and reproducibility of binocular,open-field,infrared auto ref/keratometer measurements (WAM-5500,Grand-Seiko,short for WAM autorefractor,below).Methods Two hundred seventeen students (aged 7-16 years) were consecutively enrolled in a cross-sectional study at Beijing Tongren Hospital.Autorefraction and subjective refraction were performed on each subject in both static and dynamic modes using the WAM autorefractor after other ocular diseases were excluded by completing routine ophthalmic examinations.Spherical equivalent (SE) and Jackson cross-cylinders at axes 0 and 45 (J0 and J45) were calculated; the intraclass correlation coefficient (ICC) was also calculated to assess accuracy.Autorefraction was performed twice (separated by at least 24 hours) for 14 adult volunteers (28 eyes) in both modes of the WAM autorefractor with 2 targets (6m and 20cm).Intra-test and inter-test reproducibility were evaluated using a coefficient of variation (CV) and ICC,respectively.Results The ICC of the spherical refractive error and (or) SE obtained by the two modes of the WAM autorefractor and subjective refraction were higher than 0.95 for subjects in the different age groups; J0 and J45 ranged from 0.38 to 0.84.For intra-test reproducibility,the CVs of spherical refraction,SE and pupil diameter (PD) obtained by both modes of the WAM autorefractor for the two targets ranged from 1.54％ to 8.31％; J0 and J45 ranged from 23.54％ to 32.70％.For inter-test reproducibility,the ICCs of the spherical refractive error and SE were higher than 0.90; ICCs for J0,J45 and PD ranged from 0.71 to 0.89.Conclusion Both the static and dynamic modes of the WAM autorefractor showed it is reliable and repeatable.The autorefractor has potential utility in both clinical tests and scientific research based on both its consecutive and high-speed monitor functions for three ocular responses.

Objective To compare the difference and assess the consistency between IOL Master and ALLEGRO Oculyzer for measuring anterior chamber depth (ACD).Methods It was a prospective study.Fifty-three patients (87 eyes) were recruited and ACD was measured by IOL Master and ALLEGRO Oculyzer.The statistical significance of the difference between the measurements was evaluated by a paired t test and consistency was assessed by Pearson's correlation and Bland-Altman analysis.Results The mean ACD was 3.17±0.44 mm and 3.21±0.46 mm with IOL Master and ALLEGRO Oculyzer,respectively.The difference between the two measurements was statistically significant (t=3.26,P＜0.01) and a high correlation was found between the two measurements (r=0.96,P＜0.01).Bland-Altmann analysis showed that the two measurements had comparable results for ACD with 95％ limits of consistency,-0.20 to 0.28 mm.Conclusion IOL Master and ALLEGRO Oculyzer can be used interchangeably for ACD measurement to calculate intraocular lens power.

Objective To compare the effect of an aspheric versus spherical intraocular lens (IOL) on the optical quality of high myopia patients with complicated cataract IOL implantation.Methods In a retrospective study,46 patients (46 eyes) were randomly selected to undergo phacoemulsification and implanted with either aspheric IOLs (test group,23 eyes) or spherical IOLs (control group,23 eyes).BCVA,contrast sensitivity and total higher order wavefront aberrations were assessed 3 months after cataract surgery.Results The difference in BCVA between the two groups was not significant.In an examination of contrast sensitivity under nighttime and nighttime with periglare conditions,patients implanted with aspheric IOLs performed significantly better than patients with spherical IOLs (P＜0.05).For a 5.0 mm optical zone,there was a significant reduction in spherical aberrations,RMS4,RMS5,RMS6 and RMSh in eyes implanted with aspheric IOLs (P＜0.05).Conclusion This study shows that the optical quality of high myopia and cataractous eyes implanted with aspheric IOLs is significantly better than that with spherical IOLs.

Objective To summarize and analyze the ocular conditions of patients with myasthenia gravis (MG) diagnosed in the MG therapy center and those who came for ocular consultation in our department.Methods In a retrospective case study,181 patients with MG who came for ocular consultation from January 2009 to August 2011 were analyzed,and underwent the following examinations:visual acuity,slit lamp microscope examination,fundus examination,refractive condition,eye alignment at 33 cm and 6 m,eye movement,and diplopic images by the red glass test.Some patients were also examined with a synoptophore.Data was categorized,collected and analyzed.Results Of those 181 cases,many patients were diagnosed with ocular MG (86,47.5％),150 cases had normal eye alignment (82.9％),175 cases had eyelid ptosis (96.7％),5 cases had monocular amblyopia (2.8％),and 156 patients had diplopia (86.2％).Of those 181 cases,55 patients (30.4％) had paralysis of one simple ocular muscle,77 cases (42.5％) had paralysis of multiple ocular muscles,and 13 patients (7.2％) had paralysis of all ocular muscles.Of those 55 patients with paralysis of one simple ocular muscle,most had involvement of the medial rectus (14,25.5％).Conclusion Almost half of the former patients with MG who came for ocular consultation were diagnosed with ocular MG.In patients with MG,most had eyelid ptosis and diplopia.However,most patients had normal eye alignment.The patients who developed MG early had form deprivation amblyopia because of eyelid ptosis.Paralysis of ocular muscles can involve one simple muscle,multiple muscles or all muscles,and most patients had a paralysis of multiple muscles or one simple muscle.In patients with paralysis of one simple ocular muscle,the medial rectus muscle was most often involved.

Vision has an irreplaceable significance for individuals.Vision loss inevitably affects the mental state of individuals,such as cognitive ability,character and temperament,emotion,etc.That will greatly impact visual rehabilitation.Thus full attention should be paid to psychological rehabilitation and an effective program should be developed for low vision individuals.It is necessary to perform some mental examinations,diagnosis and treatments to ensure that the rehabilitation program is designed to take the mental characteristics of individuals into account.