ABSTRACT
Background Myopia is one of the main blinding diseases worldwide.At present,a lot of studies on ocular structure focus on the changes of corneal curvature(CC),central corneal thickness (CCT),anterior chamber depth (ACD),ocular axial length (AL) and choroid and retina,but the research of anterior chamber angle section structure form and ciliary body shape is lack.Objective This study was to measure and analyze the changes of the anterior chamber angle and related tissue structure in myopic eyes.Methods One hundred and forty-nine eyes of 149 subjects were included from May 2008 to May 2010 in Eighth Hospital of Qingdao City with the ages of 18-40years old under the informed consent.The subjects were assigned to the emmetropia group (30 eyes) ([0.02±0.18] D),low myopia group(46 eyes) ([-1.64±0.69] D),moderate myopia group (35 eyes) ([-4.56±0.66] D) and high myopia group (38 eyes) ([-7.04 ± 1.02] D).Conventional indexes including intraocular pressure (IOP),CCT,CC,AL and ACD were measured,and the indexes including chamber angel open distance (AOD),iris thickness (IT1,IT2,IT3),the position of ciliary body such as A-angel,B-angel,trabecular ciliary process distance (TCPD),irisciliary process distance (ICPD) and ciliary body thickness (CBT1,CBT2,CBT3) were measured by ultrasound biomicroscope(UBM).Results The IOP,CC and CCT values showed slight change in different groups without remarkable difference among them (all at P＞0.05).As the increase of myopic degree,AL was extended and ACD was deepened,showing significant differences among the groups (both at P＜0.05).There were no significant differences in IT1,IT2 and IT3 among the four groups (all at P＞0.05).However,the measuring values of angle opening degree (TIA and AOD500),ciliary position (A-angle,B-angle,TCPD,ICPD) and CBT (CBT1,CBT2,CBT3) elevated with the increase of myopic degree (all at P＜0.05).Positive correlations were found between AOD500 and ACD,A-angle,CBT1,CBT2,AL,negative correlations was found between AOD500 and myopic degree (r =0.573,0.513,0.325,0.398,0.542,-0.435,all at P＜0.01);Positive correlations were found between TIA and ACD,A-angle,CBT1,CBT2,AL,negative correlations was found between AOD500 and myopic degree (r =0.573,0.464,0.276,0.410,0.539,-0.435,all at P ＜ 0.01).Conclusions Within certain limits,as the increase of myopic degree,ACD deepens,the anterior chamber angle widens,ciliary process thickens and ciliary body backward shifts.
ABSTRACT
Background Primary angle-closure glaucoma (PACG) is the most common type of glaucoma in China.A screening to identify the possible angle closure is important in the prevention and treatment of PACG.Objective This study was to determine the characteristics and the optimal parameters measured by the scanning peripheral anterior chamber depth analyzer (SPAC) in the screening of occludable angle of a sample of adult Chinese population.Methods A cross-sectional study was performed in Handan from February to April in 2013.One hundred and eighty Chinese adults were enrolled with the age of 40 years and older and acceptable criteria during 5-year following-up duration of the Handan Eye Study.Routine eye examinations were carried out in all subjects under the informed consent,including visual acuity,optometry,anterior ocular segment examination under the slit lamp microscope,and then SPAC measurement and gonioscopy were performed in a dark room.Occludable angle was defined as posterior trabecular meshwork being invisible in ≥ 180° range under the static gonioscope.Occludable angle by SPAC was estimated using available central chamber depth (ACD) and a combined indicator,numerical grade was 5 or fewer and/or the categorical grade was S or P,separately.Receiver operating characteristic (ROC) curve was calculated to assess the performance of these parameters in detecting eyes with occludable angle for the population-based sample,and area under curve (AUC) was drown to compare the screening efficiencies between available ACD and combined indicator.Results In 180 subjects,occludable angles were found in 62 and open angles were in 118.Compared to the subjects with open angle,the subjects with occludable angle showed the older age (P＜0.001),more females (P＜0.05),lower visual acuity (P＜0.001),greater hyperopic diopter (P＜0.05),smaller ACD value (P＜0.001) and shorter axial length(P＜0.001).In eyes with occludable angle by using SPAC,the ACD showed an AUC of 0.832.Using a cutoff of 2.7 mm for ACD,the sensitivity and specificity were 85.48％ and 68.64％,and under the cutoff of 2.8 mm,the sensitivity and specificity was 90.32％ and 61.02％,respectively.For the combined parameters,the sensitivity and specificity was 62.90％ and 90.68％,respectively and the AUC was 0.768.Conclusions When gonioscopy is used as a reference,a cutoff of 2.8 mm ACD by SPAC shows the highest sensitivity for the screening of occludable angle in Chinese population.
ABSTRACT
Background Early diagnosis of primary angle-closure glaucoma (PACG) and screening or case detection of high risk population have become a major challenge in the prevention and treatment of PACG.Commonly used methods for evaluation of anterior chamber depth (ACD) and anterior chamber angle nowadays have their shortcomings.Scanning peripheral anterior chamber depth analyzer (SPAC) measures ACD and evaluates the risk of angle closure.Also,SPAC is handy,objective and noninvasive.Objective This study was to evaluate the repeatability (within-rater differences) and reproducibility (between-rater differences) of SPAC to measure anterior chamber-related parameters and agreement of SPAC to estimate occludable angle between two operators.Methods A prospective cross-sectional study was designed.Thirty subjects with shallow ACD (modified van Herick grading≤ 3 and Shaffer grading≤2) aged 35 years and older,who met the inclusion criterion were enrolled as shallow anterior chamber group and 30 age-and gender-matched normal adults (modified van Herick grading≤3 and Shaffer grading≤2)from the follow-up research of the Handan Eye Study in February 2013.After an elementary eye examination,a randomly selected eye of each subject in both groups received three consecutive SPAC measurements by each of the two examiners,respectively to obtain ACD,central corneal thickness (CCT) and corneal radius of curvature (CRC).Meanwhile,the identity of occludable angle as the numerical grade was 5 or fewer and/or the categorical grade being S or P was also obtained.The repeatability of each examiner was evaluated by the repeatability limit (RL) and the reproducibility of the two examiners was evaluated by intraclass correlation coefficient (ICC).The agreement of occludable angle estimation between two operators was evaluated using Kappa coefficient.Results The RLs percentage for ACD,CCT and CRC ranged from 0.36％ to 3.29％,and 0.90％ to 4.72％ in the normal control group and shallow anterior chamber group from operator A,and those from operator B were 0.38％ to 2.55％,and 0.51％ to 3.42％.The ICCs for ACD,CCT and C RC of SPAC were 0.966,0.859,0.989 and 0.915,0.905,0.971,respectively from operator A and operator B.The Kappa coefficients for the identity of occludable angle between two operators were 1.000 and 0.520 in the normal control group and the shallow anterior chamber group,respectively.Conclusions Measurements of the three parameters provided by SPAC in normal and shallow anterior chamber subjects show a good repeatability and reproducibility.The results of identity of occludable angle from two examiners have a good agreement for normal subjects and a moderate reproducibility for subjects with shallow ACD.
ABSTRACT
<p><b>BACKGROUND</b>Assessment of the optic disc and retinal nerve fiber layer (RNFL) is essential for the diagnosis and monitoring of glaucoma. Knowledge of normal optic disc topography provides a benchmark for evaluating glaucomatous pathologic changes, especially in its early stages. The purpose of this study was to evaluate the characteristics and correlation factors of the optic disc parameters using the Heidelberg Retina Tomograph II (HRT II) in a large sample of normal eyes of adult Chinese subjects.</p><p><b>METHODS</b>Disc data were obtained from 6 830 subjects aged >30 years from the Handan Eye Study. All participants underwent comprehensive eye examinations and physical examinations. The associations of gender, age, body mass index, blood pressure, waist-to-hip ratio; refractive error, intraocular pressure, axial length, and disc area were assessed using simple and multiple regression analysis. The correlation between HRT II parameters was evaluated.</p><p><b>RESULTS</b>Of the 7 557 eligible subjects, 6 830 took part in the study (90.4% response rate) and 2 633 normal eyes with good-quality HRT II images were selected. The mean disc area was 2.28 mm(2) (standard deviation (SD) 0.43) and mean neural rim area was 1.80 mm(2) (SD 0.29). In multiple regression analysis, optic disc area significantly correlated with age, gender, and axial length (P < 0.001). All optic disc parameters showed a significant correlation with disc area (0.054 <r <0.736, P < 0.01). The association between mean RNFL thickness and rim area is statistically significant but not strong (regression linear equation: rim area = 1.42 × mean RNFL thickness + 1.32 mm(2), P < 0.001; R(2) = 0.070). The global RNFL cross-sectional area was significantly associated with global rim area (regression linear equation: rim area = 1.14 × RNFL cross-sectional area + 0.44 mm(2), P < 0.001; R(2) = 0.271).</p><p><b>CONCLUSIONS</b>The optic disc area in rural Chinese population is larger than reported in white and Japanese populations, similar to that of Indian population and urban Chinese population. Most optic disc measurements were moderately or weakly affected by disc area. In addition to the RNFL, there may be other factors affecting the rim area. The relationship between optic disc and axial length may suggest a link between larger disc area, thinning of the lamina cribrosa, and increased glaucoma susceptibility in myopic eyes.</p>