Ultrasound biomicroscopic measurement of anterior chamber angle in premature infants

AIM—To establish normative values for the anterior segment in premature infants in relation to postconceptional age and birth weight.
METHODS—Anterior segments were measured in 39 premature infants, 25 to 39 weeks' gestational age by use of ultrasound biomicroscopy and a muscle hook with topical anaesthesia.
RESULTS—Anterior chamber depth, trabecular-iris angle, angle opening (trabecular-iris) distances at 250 and 500 µm from the scleral spur, and the thickness of the thickest part of the iris showed linear increases in relation to postconceptional age and birth weight.
CONCLUSIONS—Ultrasound biomicroscopy is a powerful tool for obtaining precise images and measurement of the anterior segment in preterm neonates. Normative values were established for anterior segment dimensions in relation to postconceptional age and birth weight.

     

Pilocarpine induces an increase in the anterior chamber angular width in eyes with narrow angles

AIM: To determine the mechanical effects of pilocarpine on the trabecular-iris angle opening in eyes with narrow angles, compared with its effects on healthy control subjects with wide angles. METHODS: A narrow angle was defined as 25 degrees or less of trabecular-iris angle on ultrasound biomicroscopic examination. The change in anterior chamber depth (ACD), trabecular-iris angle (TIA), angle opening distance (AOD, distance between trabecular meshwork and iris) measured at 250 microm and 500 microm from the scleral spur (AOD250 and AOD500), and iris thickness was determined in 30 eyes of 30 patients (13 men and 17 women, between 63 and 82 years (mean 70.4 years)) with narrow angles and in 30 sex and age matched control subjects with wide angles before and 1 hour after the instillation of 2% pilocarpine hydrochloride by ultrasound biomicroscopy. RESULTS: In all eyes with narrow angles, pilocarpine increased the TIA, AOD250, and AOD500; these changes increased significantly and linearly as the corresponding pretreatment values decreased (r = 0.807, p = 0.0001; r = 0.787, p = 0.0001; r = 0.852, p = 0.0001). Of 30 eyes with wide angles, 23 eyes whose ACD was 2670 microm and more showed a decrease in the TIA, AOD250, and AOD500; the changes in TIA, AOD250, and AOD500 also significantly correlated with the corresponding pretreatment values (r = 0.913, p = 0.0001; r = 0.882, p = 0.0001; r = 0.895, p = 0.0001). Pilocarpine induced a smaller decrease in ACD in eyes with narrow angles than in those with wide angles (p = 0.0001). There was a linear correlation between the increase in ACD change and the decrease in pretreatment ACD in eyes with narrow angles and those with wide angles (r = 0.781, p = 0.0003; r = 0.798, p = 0.0001). CONCLUSIONS: The finding that pilocarpine increases angular width in patients with narrow angles indicates that this agent is useful for treating patients with narrow angles and angle closure glaucoma. The prediction of the pilocarpine induced change in the angle may assist ophthalmologists in treating such patients.     

Ultrasound biomicroscopy of the anterior segment after congenital cataract surgery

PURPOSE: To evaluate the structure of the anterior segment after congenital cataract surgery with ultrasound biomicroscopy. METHODS: Ultrasound biomicroscopy was performed on 28 eyes of 15 patients after congenital cataract surgery (age range, 8-27 years; mean, 13.1 +/- 1.1 years), of which 26 eyes had pars plana lensectomy and two eyes had phacoemulsification and aspiration, and on 21 eyes of 11 phakic control subjects who were healthy (age range, 6-17 years; mean, 11.5 +/- 1.1 years). The angle-opening distance at 500 microm was measured on a line perpendicular to the trabecular meshwork 500 microm from the scleral spur, and the trabecular-iris angle was measured. RESULTS: Angle-opening distance at 500 microm in the congenital cataract group ranged from 174 to 920 microm (mean, 424 +/- 28 microm), and in the control group it ranged from 260 to 1,119 microm (mean, 643 +/- 57 microm), a difference that was significantly different (P =.0004, Student t test). The trabecular-iris angle in the congenital cataract group ranged from 30.4 to 66.9 degrees (mean, 41.9 +/- 1.6 degrees) and in the control group ranged from 32.1 to 69.8 degrees (mean, 44.9 +/- 2.5 degrees), a difference that was not significantly different (P =.28, Student t test). This means that there is a tendency for high insertion of the iris in the congenital cataract group, and intraocular pressure was elevated after surgery (including glaucoma and ocular hypertension) in 10 (47.6%) of 21 eyes with high insertion. The pars plicata after congenital cataract surgery was significantly flatter than that of control subjects (P =.0057, Student t test). CONCLUSIONS: Ultrasound biomicroscopy is a useful method for evaluating the anterior segment of eyes with congenital cataract, and complications after cataract surgery can be caused by disorganization of the anterior segment. Patients with abnormalities of the anterior segment should be followed up closely for the development of glaucoma.     

Ultrasound biomicroscopic study of anterior segment changes after phacoemulsification and foldable intraocular lens implantation

PURPOSE: To report quantitative changes in the anterior segment configuration after clear corneal incision phacoemulsification and foldable intraocular lens (IOL) implantation by means of ultrasound biomicroscopy (UBM). DESIGN: Prospective, nonrandomized, comparative (self-controlled) trial. PARTICIPANTS: Twenty-one eyes of 19 patients with senile or presenile cataracts and no other ocular illness. METHODS: Patients were examined with UBM before and 1 and 3 months after surgery. At each UBM examination, axial images of the anterior chamber and radial sections of the angle at the superior, lateral, inferior, and medial quadrants were obtained. MAIN OUTCOME MEASURES: Central anterior chamber depth (ACD), iris-lens contact distance, iris-lens angle (ILA), angle opening distance at points 250 (AOD250) and 500 microm (AOD500) from the scleral spur, trabecular-iris angle (TIA), iris thickness 500 microm from the scleral spur (IT), trabecular-ciliary process distance (TCPD), iris-ciliary process distance (ICPD), iris-zonule distance, iris-sclera angle (ISA), and ciliary process-sclera angle (CPSA). After surgery, central anterior chamber depth was also measured from the cornea to the IOL (ACD) and from the cornea to the pupillary plane (ACD2). Each variable was measured twice in different days by the same observer. RESULTS: The variables IT, TCPD, ICPD, IZD, and CPSA did not significantly change after surgery (P > 0.01). Central anterior chamber depth increased approximately 30% after surgery (approximately 850 microm; P < 0.001), by both measurement methods used (ACD x ACD and ACD x ACD2). Anterior chamber angle significantly increased, by approximately 50% of the initial value, by the three measurement methods used: AOD250 (P 相似文献   

白内障超声乳化摘出术后OCT测量的眼前节结构改变

目前,白内障是世界上主要的致盲眼病,其次是青光眼.年龄相关性白内障未成熟期晶状体膨胀,构成闭角性青光眼发生的危险因素,及早进行白内障超声乳化摘出术是解决该危险因素的最佳手段.选择何时进行手术以及预后效果成为困扰临床医师的问题.本研究纳入17篇应用眼前节OCT(AS-OCT)分别对白内障超声乳化摘出术前后眼前节生物测量不同参数进行定量分析的文献,就白内障超声乳化摘出术对眼前节结构的影响进行综合评价.全部文献累计866患眼;随访时间为术后6个月.术后前房深度(ACD)、前房容积(ACV)、前房角度(ACA)、巩膜突起500 μm房角开放距离(AOD500)、AOD750、巩膜突起500 μm小梁与虹膜接触面积(TISA500)、TISA750、巩膜突起750μm房角隐窝面积(ARA750)均较术前不同程度升高,术后前房宽度(ACW)、巩膜突起750.μm处的虹膜厚度(IT750)均无明显变化,术后虹膜弯曲度(I-Curv)、虹膜横断面面积、虹膜突面积较术前降低.术前LT与术后ACD及术后TISA500均呈高度正相关.术前晶状体拱高(LV)与术后3个月ACD及术后3个月AOD500均呈正相关.综合文献证实,白内障超声乳化摘出术可解除瞳孔阻滞,减小虹膜压迫,使得前房加深和房角增宽.白内障超声乳化摘出联合人工晶状体植入术可用于青光眼的治疗,值得进一步推广.     

Comparison of anterior segment optical coherence tomography and ultrasound biomicroscopy for assessment of the anterior segment

PURPOSE: To compare anterior segment parameters using quantitative imaging by anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM). SETTING: Tertiary-care glaucoma research center. METHODS: Sixty-three eyes of 63 subjects had anterior segment evaluation by AS-OCT (Visante-Zeiss) and UBM (Paradigm). Central corneal thickness (CCT), anterior chamber depth (ACD) (measured from the central corneal endothelium to the anterior lens capsule), and the peripheral iridocorneal angles (temporal and nasal) were assessed and compared. RESULTS: There was an excellent correlation between AS-OCT and UBM measurements for the nasal angle (r = 0.84; P<.0001), temporal angle (r = 0.86; P<.0001), ACD (r = 0.97; P<.0001), and CCT (r = 0.91; P<.0001). There was no significant difference (paired t test) between the mean ACD, CCT, and angle parameters measured by AS-OCT or UBM. The mean values of the parameters measured by AS-OCT and UBM were, respectively, as follows: nasal angle, 26.25 degrees +/- 11.0 (SD) and 28.27 +/- 11.3 degrees (P = .3); temporal angle, 25.1 +/- 11.4 degrees and 28.3 +/- 13.5 degrees (P = .15); ACD, 2.85 +/- 0.5 mm and 2.78 +/- 0.5 mm (P = .2); and CCT, 512 +/- 46 microm and 502 +/- 46 microm (P = .25). The AS-OCT images showed sharper definition of the scleral spur than the UBM images. CONCLUSION: Anterior segment optical coherence tomography and UBM can both be used for anterior segment measurements and yielded comparable results.     

应用超声生物显微镜检测原发性婴幼儿型青光眼的眼前节形态特征

目的了解原发性婴幼儿型青光眼（ｐｒｉｍａｒｙｉｎｆａｎｔｉｌｅｇｌａｕｃｏｍａ,ＰＩＧ）在活体状态下的眼前节组织结构特点。方法应用超声生物显微镜（ｕｌｔｒａｓｏｕｎｄｂｉｏｍｉｃｒｏｓｃｏｐｙ,ＵＢＭ）,以５０ｍＨｚ的超高频超声探头,对３８例（５８只眼）原发性婴幼儿型青光眼的眼前节结构进行测量和动态学检查。结果ＰＩＧ患儿无论发病早晚、病情轻重或年龄大小,其最主要的病变特征是巩膜突与房角顶点的相对位置发生变化,３／４患眼的巩膜突位于房角顶点外侧或后外方,１／４患眼的巩膜突与虹膜根部附着处平行。睫状突长度和厚度均大于同龄正常儿童。睫状突向前、向内移位,部分与虹膜相贴。结论ＰＩＧ患儿的巩膜突与房角顶点相对位置的改变,提示巩膜突发育不良或虹膜附着点靠前,这是原发性婴幼儿型青光眼发病的病理基础。     

应用超声生物显微镜检查原发性婴幼儿型青光眼的眼前节形态特征

目的 了解原发性婴幼儿型青光眼在活体状态下的眼前节组织结构特点。方法 应用超声生物显微镜,以５０ｍＨＺ的超高频超声探关,对３８例（５８只眼）原发性婴幼儿型青光眼的眼前节结构进行测量和动态学检查。结果 ＰＩＧ患儿无论发病早晚、病情轻呈年龄大小,其最主要的病变特征是巩膜突与留心 角顶点的相对位置发生变化,３／４患眼的巩膜突位于房角顶点外侧或后外方,１／４患眼的巩膜突虹膜根部附着处平行,眼状突长度和厚度     

Increasing the size of a small peripheral iridotomy widens the anterior chamber angle: an ultrasound biomicroscopy study

PURPOSE: A peripheral iridotomy (PI) is the treatment of choice for pupillary block. In this study we investigated the effect of enlarging the size of a small PI on the anterior chamber angle in patients with angle closure using ultrasound biomicroscopy (UBM). PATIENTS AND METHODS: Patients who had been treated with laser peripheral iridotomy for angle closure and were identified to have a small patent PI (< 100 microm) with still appositionally closed anterior chamber angle were selected prospectively. The anterior chamber angle was assessed using UBM. The angle opening distance 500 microm from the scleral spur (AOD500) as well as the anterior and posterior chamber depth (ACD and PCD) 1000 microm from the scleral spur was measured. In addition, the ACD/PCD ratio was calculated. Afterwards, the PI was enlarged using an Nd: YAG laser and the UBM measurements were repeated as described above. RESULTS: Six eyes of six patients were examined. After the enlargement of the PI the average AOD500 increased from 109 microm (+/- 36) to 147 microm (+/- 40) (p < 0.05). The ACD/PCD ratio increased from 0.36 (+/- 0.065) to 0.67 (+/- 0.185) (p < 0.05). CONCLUSION: Patients with a small PI and appositionally closed anterior chamber angle should have a repeated laser treatment. The ACD/PCD ratio, measured 1000 microm from the sclerl spur, is a new method to describe the features and changes of the anterior chamber angle taking into account the configuration of the iris and the posterior chamber depth.     

超声生物显微镜量化观察超声乳化白内障吸除人工晶状体植入术后前房角的改变

目的　探讨超声乳化白内障吸除折叠式人工晶状体植入术后术眼前房角结构的改变。方法　对 4 6例 (5 0只眼 )老年性白内障患者行小切口超声乳化白内障吸除折叠式人工晶状体植入术 ,分别于术前和术后 1个月使用超声生物显微镜量化测量前房深度和前房角宽度。结果　全部患者术后 1个月前房深度明显增大 (P <0 0 1) ;5 0 0 μm处小梁虹膜夹角 (TIA5 0 0 )、2 5 0 μm和 5 0 0 μm处前房角开放距离 (AOD2 5 0、AOD5 0 0 )与术前比较均显著增大 (均P <0 0 1) ,TIA5 0 0平均比值 (术后TIA5 0 0 /术前TIA5 0 0 )为 1 6 5 (1 12～ 4 91) ,AOD2 5 0平均比值 (术后AOD2 5 0 /术前AOD2 5 0 )为1 81(1 0 6～ 2 6 7) ,AOD5 0 0平均比值 (术后AOD5 0 0 /术前AOD5 0 0 )为 1 6 5 (1 0 1～ 2 76 ) ,均与术前值呈显著负相关 (均P <0 0 1)。结论　超声乳化白内障吸除折叠式人工晶状体植入术可显著增大老年性白内障患者的前房角宽度 ;术前前房角越窄 ,术后前房角的变化程度越大。     

超声生物显微镜量化观察超声乳化白内障吸除人工晶状体植入术后前房角的改变

目的:探讨超声乳化白内障吸除折叠式人工晶状体植入术后术眼前房角结构的改变。方法:对46例(50眼)老年性白内障患者行小切口超声乳化白内障吸除折叠式人工晶状体植入术,分别于术前和术后1mo使用超声生物显微镜量化测量前房深度和前房角宽度。结果:全部患者术后1mo前房深度明显增大(P<0.01);500μm处小梁虹膜夹角(TIA500)、250μm和500μm处前房角开放距离(AOD250、AOD500)与术前比较均显著增大(P<0.01),TIA500平均比值(术后TIA500/术前TIA500)为1.65(1.12～4.91),AOD250平均比值(术后AOD250/术前AOD250)为1.81(1.06～2.67),AOD500平均比值(术后AOD500/术前AOD500)为1.65(1.01～2.76),均与术前值呈显著负相关(P<0.01)。结论:超声乳化白内障吸除折叠式人工晶状体植入术可显著增大老年性白内障患者的前房角宽度;术前前房角越窄,术后前房角的变化程度越大。     

Narrowing of the anterior chamber angle during Valsalva maneuver: a possible mechanism for angle closure

PURPOSE: To evaluate changes at the anterior chamber angle during Valsalva maneuver in eyes suspected to have a primary adult glaucoma. METHODS: Seventy-six consecutive patients underwent recording of applanation tonometry, measurement of the anterior chamber angle recess, angle opening distance, angle recess area, scleral spur-iris root distance, iris thickness, iridociliary angle, ciliary body thickness, anterior chamber depth, and pupil size on ultrasound biomicroscopy before and during the Valsalva maneuver. The Valsalva maneuver was standardized to a pressure of 40 mmHg for 15 seconds, using a manometer. RESULTS: The mean baseline intraocular pressure changed from 19.5+/-4.1 mmHg to 29.5+/-4.8 mmHg during Valsalva (p<0.0001). The anterior chamber angle recess narrowed from 17.9+/-9.5 to 7.8+/-9.2 degrees (p=0.0001). The angle recess area diminished from 0.15+/-0.14 mm2 to 0.14+/-0.12 mm2 (p=0.03) and the scleral spur to iris distance decreased from 0.19+/-0.2 mm to 0.16+/-0.18 mm (p=0.0001). The iridociliary angle narrowed from 72.6+/-33.5 degrees to 62.5+/-32.8 degrees (p=0.04). There was a significant increase in the thickness of the ciliary body, from 0.99+/-0.19 mm to 1.12+/-0.16 mm (p=0.001) and in iris thickness from 0.47+/-0.07 mm to 0.55+/-0.09 mm (p=0.0001). There was no significant change in the angle opening distance, anterior chamber depth, or pupillary diameter. A significant narrowing of the angle to less than 5 degrees was seen in 37 eyes, with iridocorneal apposition present in 28 eyes. After multivariate regression analysis it was found that the baseline ciliary body thickness and angle recess were significant predictors of narrowing of the angle (R2=96.1%). CONCLUSIONS: Significant elevation of the intraocular pressure, narrowing of the anterior chamber angle recess, thickening of the ciliary body, and increase in the iris thickness is seen during the Valsalva maneuver. The Valsalva maneuver may lead to angle closure in eyes anatomically predisposed to primary angle closure glaucoma.     

Ultrasound biomicroscopic morphometry of the anterior eye segment before and after one drop of pilocarpine

Purpose: To measure anterior eye segment morphometric data using ultrasound biomicroscopy. This is a new high-frequency, high-resolution ultrasound method enabling the visualisation of the anterior segment of the living eye with magnification similar to a light microscope. Methods: Thirteen morphometric parameters of the anterior eye segment were measured before and after the application of one drop of pilocarpine in 10 eyes of 5 persons, using a Zeiss-Humphrey Ultrasound Biomicroscope at a frequency of 50 MHz. In each session, 3 morphometric parameters in the central images (corneal thickness, anterior chamber depth, pupillary diameter) were measured 4 times, and 10 parameters in the radial images (scleral thickness, angle-opening distance, trabecular-iris angle, trabecular-ciliary process distance [TCPD], iris thickness 1, 2 and 3, iris-ciliary process distance, iris-lens contact distance [ILCD], iris elevation) were measured on the 3, 6 and 9 o'clock meridians three times each. Results: Statistically significant changes were noted in the following parameters: pupillary diameter, iris thickness 1 and 2, and TCPD were decreased, while ILCD was increased after pilocarpine. Wide chamber angles showed a tendency to become narrower and narrow ones to become wider after pilocarpine. Conclusion: One drop of pilocarpine caused significant changes in the anterior eye segment morphology. Not only the pupillary diameter decreased but iris thickness and trabecular-ciliary process distance were also decreased simultaneously. At the same time the contact surface between the lens and iris increased significantly. Ultrasound biomicroscopy gives new morphometric image information about the anterior eye segment which is not available using conventional gonioscopy or ophthalmic echography.Abbreviations ACD anterior chamber depth - AOD500 angle-opening distance - CD corneal thickness - Fi1 trabecular-iris angle - ICPD iris-ciliary process distance - ID1, ID2 and ID3 iris thickness 1, 2 and 3 - IE iris elevation - ILCD iris-lens contact distance - PD pupillary diameter - SD scleral thickness - TCPD trabecular-ciliary process distance     

Ultrasound biomicroscopy dark room provocative testing: a quantitative method for estimating anterior chamber angle width

PURPOSE: To describe a quantitative method for measuring the iridocorneal angle recess area, and, using this, to evaluate factors associated with appositional angle-closure during dark room provocative testing using ultrasound biomicroscopy (UBM). METHODS: All patients (178 patients, 178 eyes) with clinically narrow angles referred for UBM dark room provocative testing between September 1996 and March 1998 were enrolled in this study. Images of the inferior quadrant of the angle taken under standardized dark and light conditions were analyzed. The angle recess area (ARA) was defined as the triangular area demarcated by the anterior iris surface, corneal endothelium, and a line perpendicular to the corneal endothelium drawn from a point 750 microm anterior to the scleral spur to the iris surface. ARA, and acceleration and gamma-intercept of the linear regression analysis of the ARA were calculated. In the linear regression formula, y = ax + b, the acceleration a describes the rate at which the angle widens from the scleral spur; the y-intercept b describes the distance from the scleral spur to the iris. RESULTS: Under dark conditions, the angles in 99 patients (55.6%) showed evidence of appositional angle-closure during testing. ARA (0.11 +/- 0.04 vs. 0.15 +/- 0.05 mm2, P < .0001, Student t-test), acceleration a (0.22 +/- 0.15 vs. 0.26 +/- 0.17, P = .068), and y-intercept b (66 +/- 46 vs. 92 +/- 47 microm, P = .0003) were smaller in eyes that were occluded. In the eyes that were not occluded, y-intercept b showed no significant difference between light and dark conditions (P = .1, paired t-test), while acceleration a did (P < .0001). In the eyes that were occluded, both decreased significantly under dark conditions (P < .0001). CONCLUSIONS The ARA linear regression formula provides useful quantitative information about angle recess anatomy. The more posterior the iris insertion on the ciliary face, the less likely the provocative test will be positive.     

Recent advances in ophthalmic anterior segment imaging: a new era for ophthalmic diagnosis?

Anterior segment imaging is a rapidly advancing field of ophthalmology. New imaging modalities, such as rotating Scheimpflug imaging (Pentacam-Scheimpflug) and anterior segment optical coherence tomography (Visante OCT and Slit-Lamp OCT), have recently become commercially available. These new modalities supplement the more established imaging devices of Orbscan scanning slit topography and ultrasound biomicroscopy (UBM). All devices promise quantitative information and qualitative imaging of the cornea and anterior chamber. They provide a quantitative angle estimation by calculating the angle between the iris surface and the posterior corneal surface. Direct angle visualisation is possible with the OCT devices and UBM; they provide images of the scleral spur, ciliary body, ciliary sulcus and even canal of Schlemm in some eyes. Pentacam-Scheimpflug can measure net corneal power, a feature particularly useful for cataract patients having undergone previous corneal surgery. Anterior segment OCT can measure corneal flap depth following LASIK and anterior chamber width prior to phakic intraocular lens implantation. The arrival of the new imaging devices may herald the dawn of a new era for ophthalmic diagnosis, particularly in view of the ease and non-contact nature of examination.     

Imaging of iris lesions with high-speed optical coherence tomography.

BACKGROUND AND OBJECTIVES: To image and measure iris tumors with optical coherence tomography (OCT). PATIENTS AND METHODS: High-speed (2,000-4,000 axial-scan/sec and 4-16 frames/sec) 1.3-micron wavelength anterior segment OCT prototypes were used to image 6 eyes of 6 patients with a variety of iris lesions, including focal iris nevus, diffuse iris nevus, amelanotic iris nevus, iris melanocytosis, and iris melanoma. OCT images were compared with slit-lamp photography and ultrasound biomicroscopy. RESULTS: OCT at 1.3-micron wavelength could penetrate the full thickness of the iris lesions and allow three-dimensional measurement of lesion size. Internal reflectivity is correlated with pigmentation. OCT is a convenient non-contact method that provides imaging of the clinically important angle structures (scleral spur and angle recess). CONCLUSIONS: OCT is a new imaging modality that complements slit-lamp photography and ultrasound biomicroscopy for serial evaluation of iris     

A prospective ultrasound biomicroscopy evaluation of changes in anterior segment morphology after laser iridotomy in Asian eyes

PURPOSE: To prospectively quantify changes in anterior segment morphology after laser iridotomy using gonioscopy and ultrasound biomicroscopy (UBM). DESIGN: Prospective comparative observational case series. PARTICIPANTS: Fifty-five fellow eyes of patients presenting with acute primary angle closure (APAC). METHODS: The fellow eyes of patients presenting with APAC were examined with UBM, A-scan ultrasonography, and optical pachymetry at presentation and 2 weeks after sequential argon/neodymium yttrium-aluminum-garnet laser peripheral iridotomy (LPI). UBM images were analyzed using UBM Pro 2000 software. Baseline measurements were made both under standard lighting conditions and in darkness to look for changes in anterior segment findings. MAIN OUTCOME MEASURES: The degree of angle opening was measured using the angle-opening distance (AOD) at 250 and 500 microm from the scleral spur (AOD250 and AOD500, respectively) and angle recess area (ARA). RESULTS: Fifty-five Asian patients were examined; AOD250, AOD500, and ARA all significantly increased after sequential laser iridotomy (P < 0.002). Gonioscopic grading of the angle opening significantly increased in all 4 quadrants (P < 0.001). The Van Herick grade of limbal anterior chamber depth increased (P < 0.001), whereas the number of eyes classified as occludable decreased (73%-33%, P < 0.001). Anterior chamber depth did not change significantly (2.41 mm +/- 0.28 mm vs. 2.42 mm +/- 0.30 mm, P = 0.43) as measured with optical pachymetry. Increased illumination increased the angle-opening measures, but induced a different alteration in peripheral iris morphology. Illumination-induced changes were greater after iridotomy than before laser treatment. CONCLUSIONS: In Asian eyes at high risk of developing APAC, sequential LPI produced a significant widening of the anterior chamber angle without deepening the anterior chamber centrally. LPI produces changes in iris morphology that are different from those caused by an increase in illumination, indicating that different mechanisms account for angle opening under these 2 conditions.     

Ultrasound biomicroscopy in the subtypes of primary angle closure glaucoma

PURPOSE: To evaluate the anterior segment parameters in the subtypes of primary angle closure glaucoma (PACG) using ultrasound biomicroscopy. METHODS: Five groups, each comprising 30 consecutive patients, diagnosed to have subacute PACG, acute PACG, chronic PACG, primary open angle glaucoma (POAG), and healthy controls were included in the present study. All patients underwent slit-lamp biomicroscopy, direct ophthalmoscopy, 90D fundus examination, gonioscopy, applanation tonometry, visual field testing, A-scan biometry, and ultrasound biomicroscopy (UBM). The anterior segment parameters recorded included: trabecular-iris angle, angle opening distance, trabecular ciliary process distance, and the iris thickness among other parameters. RESULTS: On ultrasound biomicroscopy the trabecular iris angle of control and POAG groups was more than all the subtypes of PACG (P < 0.001). The trabecular iris angle of subacute PACG (P < 0.001) and chronic PACG (P = 0.003) was more than acute PACG. Angle opening distance of controls and POAG group was significantly more than acute PACG and chronic PACG (P < 0.001). The trabecular ciliary process distance of POAG group and controls was more than subacute PACG, acute PACG, and chronic PACG. The trabecular ciliary process distance of subacute PACG (P < 0.001) and chronic PACG (P < 0.001) was more than acute PACG. Eyes with acute PACG had the least iris thickness at the three different positions tested. There was a positive correlation between the anterior chamber angle (trabecular iris angle) and the following parameters: trabecular ciliary process distance, angle opening distance, anterior chamber depth, and the axial length (r = 0.57). CONCLUSION: Eyes with primary angle closure glaucoma have a thinner iris with a shorter trabecular iris angle, angle opening distance, and trabecular ciliary process distance. The eyes with acute primary angle closure glaucoma have the narrowest angle recess.     

Comparison between the anterior chamber configuration in the supine position and that in the prone position in patients with narrow angle]

PURPOSE: To determine whether the anterior chamber configuration of patients with narrow angle is changed in the prone position. PATIENTS AND METHODS: The study included 16 eyes of 16 patients whose anterior chamber angle was classified as Shaffer 2 or narrower. The prone position test(PPT) and ultrasound biomicroscopy (UBM) were performed on every subject. In the UBM examination, the following parameters were measured both in the supine position and in the prone position: the angle-opening distance at 250 microns from scleral spur(AOD 250), the angle-opening distance at 500 microns from scleral spur(AOD 500), the trabecular-iris angle(TIA), and the anterior chamber depth at the center of the cornea(anterior chamber depth, ACD). RESULTS: While the intraocular pressure was higher after PPT than before the test, every subject was evaluated as negative for PPT. Mean value of every parameter examined was lower in the prone position than in the supine position(AOD 250: 114 microns, vs. 128 microns, AOD 500: 121 microns vs. 144 microns, TIA: 12.1 degrees vs. 15.5 degrees, ACD: 1966 microns vs. 2002 microns), and the change in ACD was statistically significant (p = 0.013). CONCLUSIONS: The anterior chamber configuration of patients with narrow angle is changed in prone position. Such a change can occur in patients classified as negative for PPT.     

1310 nm傅里叶域眼前节OCT的成像特点及与其他两种OCT的对比分析

目的 探讨1310 nm傅里叶域实时眼前节光学相干断层扫描(OCT)的成像特点及与RTV-ue100 OCT,Visante OCT对眼前节重要结构的成像能力的对比.方法 横断面研究.选择受试者6例(12眼,24个方位),运用1310 nm傅里叶域实时眼前节OCT,RTV-ue100 OCT与Visante OCT进行房角成像,对巩膜突、Schlemm's管、房角隐窝及Schwalbe线进行定义,测量前房角角度(TIA500)、500 μm前房角开放距离(AOD500)、500 μm小梁虹膜面积(TISA500)、Schlemn's管长径以及面积.运用Fisher's确切概率法对比3台仪器对房角重要结构的定义能力,并采用独立样本t检验研究三者生物学测量结果的差异.结果 傅里叶域实时眼前节OCT可在8眼(67％)13方位(54％)、12眼(100％)22方位(92％)、12 眼(100％)24方位(100％)及6眼(50％)9方位(38％)分别定义巩膜突、Schlemm's管、房角隐窝及Schwalbe线.RTV-ue100 OCT可于8眼(67％)8方位(33％)定义Schlemm's管,10眼(83％)19方位(79％)定义Schwalbe线,不能定义巩膜突与房角隐窝.Visante OCT于12眼(100％)21方位(88％)定义巩膜突,12眼(100％)24方位(100％)定义房角隐窝,不能定义Schlemm's管与Schwalbe线.3种OCT对巩膜突、Schlemm's管、房角隐窝、Schwalbe线定义能力差异有统计学意义(F=24.30、25.20、28.22、17.10,P＜0.01).傅里叶域实时眼前节OCT与Visante OCT测量TIA500、AOD500、TISA500的差异无统计学意义.傅里叶域实时眼前节OCT与RTV-ue100 OCT测量Schlemm's管面积、长径差异无统计学意义.结论 三种OCT都实现了前房角的清晰成像,显示角膜、巩膜、结膜以及巩膜突、Schlemm's管与Schwalbe线等房角结构.RTV-ue OCT和傅里叶域实时眼前节OCT的图像分辨率较高,能够显示Schlemm’s管与Schwalbe线等细微结构;Visante OCT和傅里叶域实时眼前节OCT深层结构检测能力强,各设备所得生物学参数无明显差异.