UBM对Ⅱ期后房人工晶状体植入术的应用价值

目的评价超声生物显微镜（UBM）对Ⅱ期后房人工晶状体（IOL）植人术的临床应用价值。方法连续收集散瞳后裂隙灯显微镜观察不到残留后囊情况,需行Ⅱ期IOL植入术的25例（30眼）,术前应用UBM观察周边部残留囊的范围,虹膜和囊粘连的位置和程度,以初步选择后房型IOL的类型和植入方式;术后3个月时观察IOL的位置,并分析视力、眼压、角膜内皮细胞数量变化及IOL表面色素沉积情况。结果术前根据UBM显示残留囊情况,分别采用折叠式和非折叠式2种IOL,并计划3种方式植入,分别为A组：睫状沟支撑型折叠式IOL植入（13眼）;B组：仅一襻睫状沟缝线固定非折叠式IOL植入（9眼）;C组：两襻均以睫状沟缝线固定非折叠式IOL植入（8眼）。此结果与手术过程中手术显微镜直视观察下所见完全一致,均按原计划成功植入后房IOL。术后3个月时,均无IOL脱位发生。UBM示IOL位于角膜中央后的距离3组差异无统计学意义（P〉0．05）;A组有9眼双襻均位于睫状沟（睫状沟-睫状沟固定）,另4眼一襻位于睫状沟,另一襻位于睫状体。B组有7眼双襻均位于睫状沟,另2眼一襻位于睫状沟,另一襻位于睫状体。C组有6眼双襻均位于睫状沟,另2眼一襻位于睫状沟,另一襻位于睫状体。IOL光学部与虹膜接触率3组差异无统计学意义（P〉0．05）。尽管IOL襻的位置不同,3组之间角膜内皮数量、眼压变化及IOL表面色素沉积的发生率等差异均无统计学意义（P〉0．05）。术后3个月时,所有术眼的裸眼或矫正视力均达到或接近于术前最好矫正视力。结论UBM可作为Ⅱ期后房型IOL植入术前选择IOL类型及手术方式的依据。     

超声生物显微镜与IOL-Master测量人眼睫状沟直径的比较性研究

目的:比较分析超声生物显微镜(ultrasound biomicroscopy,UBM)与IOL-Master测量人眼睫状沟直径的差异,为更准确地计算有晶状体眼后房型人工晶状体植入术(phakicposterior chamber intraocular lens,PPCIOL)也称为可植入的接触镜(implantable contact lens,ICL)的直径提供客观依据(以下简称ICL),从而有效减少术后并发症。方法:选取植入ICL术后1mo的高度近视眼患者32例(60眼)和正视对照组人群28例(48眼),分别作为实验组和对照组,对照组要求排除任何眼科手术史。应用UBM分别测量实验组和对照组的睫状沟直径;应用IOL-Master测量实验组和对照组的角膜横径即水平白到白的距离(whitetowhite,W-W),将所得的数据进行统计学分析。结果:植入ICL后1mo患者的UBM测得的睫状沟直径与IOL-Master测得的W-W值比较其差异有统计学意义(t=2.023,1.988;P<0.05);健康人眼的UBM测得的睫状沟直径与IOL-Maste测得的W-W值比较其差异有统计学意义(P<0.05);ICL术后患者与健康眼的UBM测得的睫状沟直径值比较其差异无统计学意义;二者的IOL-Master测得的W-W值比较其差异也无统计学意义。结论:UBM可以作为测量人眼睫状沟直径的工具;应用IOL-Master眼外测得W-W值与UBM测得的睫状沟直径值是有区别的,我们更倾向于应用UBM测得的值;人眼是存在解剖变异的,这些变异会增加ICL植入的危险性。     

Visante OCT测量前房直径与IOL Master测量角膜水平直径的比较

目的分析比较应用Visante前段OCT测量的前房直径与应用IOL Master测量的角膜水平直径（白到白距离,white—to—white,WTW distance）之间的关系和差异。方法分别应用Visante OCT（Carl Zeiss Meditec）和IOL Master（Carl Zeiss Meditec）对42名患者（8d眼）进行前房直径和WTW的测量,分析比较这两者之间的差异和相关性。结果应用Visante OCT测量的前房直径为（12．11±0．33）mm,应用IOL Master测量的WTW值为（11．89±0．31）mm,两者之间的差异有非常显著的统计学意义（P〈0．01）。两者具有一定的相关性（r=0．82,P〈0．05）,前房直径比WTW长（0．21±0．19）mm,其差值95％可信区间为（-0．16mm,0．59mm）。结论应用IOL Master测量的角膜水平直径与Visante OCT测量的前房直径存在一定的差异,前段Visante OCT测量简易．数据图像更为直观,可靠性更好,在有晶状体眼人工晶状体植入等手术中具有更好的应用和指导价值。     

白内障患者应用Pentacam和UBM测量前房直径、前房深度的研究

目的探讨应用Pentacam三维眼前段分析诊断系统与全景超声生物显微镜（UBM）观察年龄相关性白内障患者手术前后前房直径及前房深度（ACD）的变化。比较两种方法测量结果的差异。方法前瞻性非随机对照临床研究。临床选取行晶状体超声乳化吸出联合人工晶状体（IOL）植人术后的年龄相关性白内障60例（79眼）。应用Pentaeam测量术前、术后1周、1个月、2个月的水平前房直径和ACD;应用UBM测量术前、术后2个月的水平前房直径、垂直前房直径和ACD。结果（1）Pentacain测量结果,术后水平前房直径增加（F=7．170,P=0．009）,ACD加深（F=26．439,P〈0．05）,术后1周、1个月、2个月前房直径、ACD进行两两比较,差别无统计学意义（P〉0．05）。（2）UBM测量结果,大部分患眼垂直前房直径大于水平前房直径。（3）Pentacam测量术前、术后2个月的水平前房直径与UBM测量值相比,差别无统计学意义（t=0．231,P=0．818,t=1．017,P=0．311）。Pentacam与UBM测量术前ACD,差别无统计学意义（t=0．153,P=0．995）;而测量术后ACD,差别有统计学意义（P〈0．05）。结论（1）Pentacam测量结果显示,年龄相关性白内障患者术后水平前房直径增加,ACD加深,术后1个月前房直径、ACD保持不变。（2）UBM测量结果显示,大部分患者垂直前房直径大于水平前房直径。（3）UBM与Pentacam都可以用于前房直径和ACD的测量,而且对于术前、术后前房直径以及术前ACD的测量结果相似。但测量白内障患者有晶状体眼的ACD时,两种仪器的测量结果不同。两种仪器测量角膜部位不同从而产生差别。但是每一种仪器都有各自的优缺点,使用时应根据不同的目的选用不同的仪器。     

原发性急性闭角型青光眼小梁切除术前后眼前节超声生物显微镜测量比较

目的通过超声生物显微镜（UBM）眼前节测量了解急性闭角型青光眼行小梁切除术后眼前节组织空间结构变化。方法对20例（21只眼）急性闭角型青光眼患者,术前及术后3个月行UBM测量中央前房深度、房角开放距离、小梁网睫状突距离、虹膜厚度、虹膜晶状体接触距离。结果术前与术后比较,中央前房深度、小梁网睫状突距离、虹膜厚度无统计学差异（P〉0．05）,房角开放距离、虹膜晶状体接触距离差异有统计学意义（P〈0．05）。结论急性闭角型青光眼患者行小梁切除术后,房角开放距离增加,瞳孔阻滞缓解,但睫状突前位没有改变。UBM是一种客观的、有效的随访工具。     

Pentacam及UBM测量原发性闭角型青光眼前房深度一致性的研究

目的探讨Pentaeam与超声生物显微镜（UBM）测量原发性闭角型青光眼（PACG）中央前房深度（ACD）结果的一致性。方法选取PACG患者77例（77眼）,分为2组：急性闭角型青光眼（APACG）患者37例（37眼）,慢性闭角型青光眼（CPACG）患者40例（40眼）。应用Pentacam及UBM分别测量其中央ACD。结果APACG组Pentacam测得的ACD为（1．6467±0．2687）mm,UBM测得的ACD为（1．5601±0．2677）mm,差异有统计学意义（t=-7．259,P〈0．01）,2种方法在测量ACD时呈正相关（r：0．939,P〈0．01）。CPACG组Pentacam测得的ACD为（2．0622±0．2317）mm,UBM测得的ACD为（1．9648±0．2176）mm,差异有统计学意义（t=-10．433,P〈0．01）,2种方法在测量ACD时呈正相关（r=0．967,P〈0．01）。应用Bland—Altman分析对2种测量方法进行一致性评价,2种方法测量ACD值的结果具有较好的一致性。结论Pentacam作为一种新型的三维眼前节分析诊断系统,在测量PACG的中央ACD时与UBM有一定差异,但其差异在临床可接受范围内,其值可相互替代使用。在临床工作中应把二者的优势结合起来,综合分析。     

三种仪器测量水平角膜直径的差异及其与睫状沟直径的一致性研究

目的探讨三种常用仪器测量水平角膜直径的差异及其水平睫状沟直径的一致性。方法横断面研究。选取苏州大学附属理想眼科医院于2018年1月至2021年12月行术前检查的屈光不正者870人(1 740眼)。年龄17～49(27.76±6.60)岁。所有受试者均行Pentacam、IOLMaster 700、OPD-Scan Ⅲ眼部生物测量, 眼状沟直径应用UBM检查。分析前3种仪器所测量水平角膜直径之间的差异及与睫状沟直径之间的差异。结果 3种仪器所测水平角膜直径最大的是IOLMaster[(12.00±0.39)mm];其次是OPD-Scan Ⅲ[(11.85±0.40)mm];最小的是Pentacam[(11.59±0.38)mm], 总体差异有统计学意义(F=281.69, P<0.001)。IOLMater所测得的水平角膜直径比水平睫状沟直径大(0.49±0.32)mm(差值的95%一致性界限:-0.14, 1.13);OPD-Scan Ⅲ所测水平角膜直径与水平睫状沟直径的差值为(0.34±0.32)mm(95%LoA:-0.29, 0.98);Pentacam所测水平角膜直径与水...     

使用全景超声生物显微镜观察年龄相关性白内障超声乳化手术后前房直径的改变

目的探讨使用全景超声生物显微镜（ultrasound biomicroscopy,UBM）观察白内障患者手术前后前房直径的改变。方法对109例（128眼）年龄相关性白内障患者行超声乳化白内障吸除联合折叠型人工晶状体植入术,分别于术前、术后第2个月利用全景UBM测量水平前房直径和垂直前房直径,观察其变化情况。结果年龄相关性白内障患者术前水平前房直径为（11.58±0.43）mm,术后为（11.82±0.35）mm;术前垂直前房直径为（11.59±0.44）mm,术后为（11.87±0.33）mm。术前垂直前房直径与水平前房直径相差（0.01±0.23）mm,术后相差（0.06±0.25）mm。术后水平、垂直前房直径均较术前增加,差异有统计学意义（P〈0.01）。术前与术后水平前房直径存在正相关（r=0.68,P〈0.01）,回归方程为Y=5.3945＋0.55438x。结论白内障患者垂直前房直径略大于水平前房直径;年龄相关性白内障超声乳化吸除人工晶状体植入术后水平前房直径及垂直前房直径均增加。可以用术前的前房直径预测出术后前房直径,为选择适合大小的前房型人工晶状体提供参考。     

LASIK手术前后IOLMaster、OrbscanⅡ及超声法测量角膜曲率、前房深度及眼轴长度的比较

背景角膜曲率、前房深度、眼轴长度的精确测量对人工晶状体（IOL）度数的计算至关重要,不同方法的测量结果可能对IOL度数的计算结果产生误差。目的比较光学相干生物测量仪（IOLMaster）、OrbscanⅡ眼前节分析仪（OrbscanⅡ）以及A型超声法测量近视患者准分子激光角膜原位磨镶术（LASIK）手术前后角膜曲率（K）、前房深度以及眼轴长度的结果。方法收集近视患者65例130眼,对LASIK手术前及手术后1个月随访到的28例56眼分别行IOLMaster、OrbscanⅡ以及A型超声法眼部生物测量,并对其结果进行比较。结果LASIK手术前,IOLMaster和OrbscanⅡ测量角膜K值分别为（43．32±1．52）D和（42．99±1．45）D,二者相差（0．33±O．03）D,差异有统计学意义（t=10．380,P=0．000）。手术后K值分别为（39．02±2．14）D和（38．91±2．04）D,二者相差（0．12±0．33）D,差异有统计学意义（t=2．715,P=0．009）。Bland—Ahman分析显示,2种方法测量K值的一致性较差。手术前IOLMaster、OrbscanⅡ和A型超声法测得前房深度分别为（3．72＋0．22）、（3．69±0．22）、（3．75±0．27）mm,差异无统计学意义（P=0．100）。A型超声法测量眼轴长度为（25．22±O．99）mm,IOLMaster测得长度为（25．59±1．01）mm,二者相差（-0．37±0．30）mm,差异有统计学意义（t=-14．098,P=0．000）,Pearson相关性分析显示二者呈正相关（r=0．954,P=0．000）。手术前后IOLMaster测量眼轴长度分别为（25．54±1．05）mm和（25．48±1．01）mm,二者相差（0．052±0．412）mm,差异无统计学意义（t=0．946,P=0．348）。结论IOLMaster测量角膜曲率与OrbscanⅡ测量结果差别较大,临床上二者不可替代。IOLMaster与OrbscanⅡ测量前房深度结果一致性较好,临床上可替代使用。与A型超声法比较,IOLMaster测得的眼轴长度较长,临床应用要引起注意。     

应用超声生物显微镜对挫伤性近视发病机制的研究

目的应用超声生物显微镜（UBM）并结合普通超声波,初步探讨挫伤性近视的发病机制。方法对51例（66只眼）眼球钝挫伤患者,在急性期和恢复期分别用自动验光仪测量屈光度;A超测量晶状体厚度;UBM测量角膜厚度、前房轴深、小梁睫状突距离（TCPD）、A角、睫状突的高度（T值）;66例正常眼为对照进行分析。结果眼球受钝挫伤后均表现为近视;且急性期晶状体变厚、前房变浅、TCPD缩短、A角变小、T值增大（P〈0．05）;而角膜厚度变化不明显（P〉0．05）。对照组各参数比较无明显差异（P〉0．05）。结论挫伤性近视的发病有诸多因素。除睫状肌痉挛外,前房变浅、晶状体变凸是共同机制;而睫状体肿胀及位置的改变是原发因素;UBM具有重要的临床应用价值。     

高度近视有晶状体眼后房型人工晶状体植入术后眼前节解剖变化

目的 分析高度近视眼患者植入有晶状体眼后房型人工晶状体（Visian ICL V4）术后眼前节解剖结构的变化.方法 本研究入选行有晶状体眼人工晶状体植入术的高度近视患者93例（175眼）,平均年龄（30.52 ±7.00）岁（18～48岁）,其中119眼接受ICL植入术,46眼接受Toric-ICL植入术.比较术前和术后1周前房容积（ACV）、前房深度（ACD）、房角角度（ACA）（3：00 ～9：00位方向）变化、ICL光学区后表面到晶状体前囊膜中央距离（拱高）、角膜-晶状体间距、虹膜-晶状体间距、人工晶状体等效球镜（pIOL SE）等各参数间的关系.结果 术前、术后1周ACV分别为（200.29±31.76） mm3及（116.49±21.88） mm3,ACV减少（t=48.456,P=0.000）.术前、术后ACD由（3.17 ±0.23） mm减少到（2.89±0.33） mm（t=12.237,P=0.000）,术前、术后房角由（36.40 ±4.90）°减少到（23.44 ±5.07）°（t=31.131,P=0.000）;术后ACV和术后ACD与术后ACA呈现正相关（分别为r=0.637,P=0.000;r=0.393,P=0.000）.术后的角膜-晶状体间距较术前增加（0.40 ±0.31） mm（t=-16.935,P=0.000）,其与拱高呈正相关（r=0.446,P=0.000）.多因素回归分析,拱高与角膜-晶状体间距比值、手术前后的瞳孔变化率是独立的手术前后角膜-晶状体间距变化的影响因素（分别是P =0.001和P=0.048）.结论 ICL植入术后,虹膜平面抬升,使前房容积变小和房角变窄.     

玻璃体切割术后早期高眼压的UBM临床观察

目的 通过超声生物显微镜（UBM）对玻璃体切割手术前后患眼进行检测比较,探讨玻璃体切割术后早期高眼压的发病机制。方法 应用UBM观察玻璃体切割手术前后患者眼前节结构的变化,分别比较有晶状体组、人工晶状体组术前术后各测量参数的变化。结果 高眼压组术后瞳孔阻滞,睫状体全周脱离、水肿、前旋。参数测量：有晶状体组的高眼压组与正常眼压组前房深度相比差异有统计学意义（t=2.000,P=0.049）,房角开放距离500高眼压组与正常眼压组相比差异有统计学意义（t=2.069,P=0.050）。人工晶状体组的高眼压组与正常眼压组前房深度相比有统计学意义（t=2.066,P=0.050）,高眼压组与正常眼压组睫状体厚度比较差异有统计学意义（t=1.926,P=0.037）。结论 术后睫状体水肿前旋致前房变浅、房角变窄,导致眼压升高,参数测量提示有晶状体高眼压组术后较术前有前房变浅、房角开放程度减小的趋势。     

原发性房角关闭眼激光虹膜切除术后UBM测量参数比较

目的:比较激光虹膜切开术前后原发性房角关闭(primary angle closure,PAC)眼超声生物显微镜(ultrasound biomicroscopy,UBM)参数。方法:对46例74眼PAC患者进行了一项前瞻性临床试验。平均年龄58,04±11.33(24.0-82.0)岁。所有病例行完整的眼科检查,前房角镜A超生物测量和超声生物显微镜检查(Vu-max,SonomedInc.,NY,USA)及24-2标准无色差视野检查(SAP,Humphrey Visual Field Analyzer-II i,Carl Zeiss Meditec Inc.,Dublin,CA,USA)。使用配对t检验评估基准和随访的平均值之间的变化。结果:激光周边虹膜切除术(laser peripheral iridotomy,LPI)术后,平均房角从8.02±4.61(0.10-19.60)度增加到17.66±6.39(0.10-32.70)度(P=0.000),房角开放距离500(angle opening distance 500,AOD500)从0.11±0.06(0.01-0.30)mm增加到0.23±0.07(0.13-0.50)mm(P=0.000),平均虹膜厚度(iris thickness,IT)从0.58±0.11(0.33-0.99)mm下降到0.52±0.10(0.25-0.77)mm(P=0.000)。小梁睫状突距离,虹膜睫状突距离和睫状体厚度均未发现显著统计学差异。结论:LPI术后PAC的白种人眼睛的AOD500,虹膜晶体距离和前房角增加,IT和虹膜晶体高度减少。这说明LPI解除了瞳孔阻滞,加深了前房,扩大了房角,减少了虹膜前凸和增厚。     

睫状体形态和位置对眼前段空间结构的影响

目的:探讨正常人眼睫状体形态和位置对眼前段空间结构的影响。方法:应用超声生物显微镜(UBM)、A超、Pentacam三维眼前段图像分析仪测量186例186眼正常人睫状体厚度(CBT)、睫状突长度(CPL)、巩膜睫状突夹角(θ)、前房体积(ACV)、前房深度(ACD)、晶状体厚度(LT)、相对晶状体位置(RLP)、房角开放距离(AOD500)。采用直线相关与回归分析方法分析CBT,CPL,θ与ACV,ACD,LT,RLP,AOD500的相关关系。结果:正常人CBT,CPL,θ与ACV,ACD,LT,RLP,AOD500分别为0.740±0.099mm,1.228±0.166mm,45.81°±5.11°,171.15±44.23mm3,2.822±0.314mm,4.29±0.48mm,0.231±0.013,0.373±0.069mm。CBT与ACV,ACD,RLP正相关,与LT负相关,与AOD500无相关性;CPL与ACV,ACD,RLP,AOD500负相关,与LT正相关。θ与ACV,ACD,RLP,AOD500正相关、与LT无相关性。结论:睫状体形态与位置是眼前段空间结构差异的影响因素。     

Correlation between quantity of silicone oil emulsified in the anterior chamber and high pressure in vitrectomized eyes

PURPOSE: To assess the existence of any correlation between the quantity of silicone oil emulsified in the anterior chamber and the incidence of high intraocular pressure in vitrectomized eyes. METHODS: Forty-nine eyes of 49 patients underwent vitrectomy with silicone oil injection as an adjuvant procedure. At the time of observation, between September 1999 and September 2000, 13 eyes (26.5%) were phakic; 23 eyes (47%) were pseudophakic; and 13 eyes (26.5%) were aphakic. Ultrasound biomicroscopy, slit-lamp biomicroscopy, and gonioscopy were performed to quantify the presence of silicone oil emulsified in the anterior chamber. RESULTS: The 13 phakic eyes did not have a high intraocular pressure. In 8 of the 13 eyes, ultrasound biomicroscopy detected only scarce oil emulsification in the anterior chamber (0.304 mm); in 5 of the 13 eyes, gonioscopy and ultrasound biomicroscopy did not detect anterior chamber oil emulsification. Fourteen of 23 pseudophakic eyes had a high intraocular pressure; of these, ultrasound biomicroscopy detected an abundant amount of anterior chamber oil emulsification (0.922 mm). Nine of 23 pseudophakic eyes did not have a high intraocular pressure; of these, ultrasound biomicroscopy detected little anterior chamber oil emulsification (0.209 mm). The 13 aphakic eyes had a high intraocular pressure; of these, ultrasound biomicroscopy detected an abundant amount of anterior chamber oil emulsification (0.795 mm). The coefficient of correlation for the measurements obtained was 0.98 (F = 62.3, P = 0.05; t = 11.1, P = 0.001). CONCLUSION: This study showed a high correlation between the incidence of high intraocular pressure and the quantity of emulsified silicone oil in the anterior chamber.     

Does an iridotomy provide protection against narrowing of the anterior chamber angle during Valsalva maneuvre in eyes with primary angle closure

PURPOSE: To evaluate changes at the anterior chamber angle during Valsalva manoeuver, in eyes having primary angle closure (PAC) and a patent laser peripheral iridotomy. METHODS: Twenty-three eyes of 23 consecutive patients underwent a recording of applanation tonometry, measurement of the anterior chamber angle recess, angle opening distance, iris thickness, anterior chamber depth, and pupil size on ultrasound biomicroscopy before and during the Valsalva maneuver. The Valsalva manoeuver was standardized to a pressure of 40 mmHg for 15 s, using a manometer.RESULTS:The mean baseline intraocular pressure changed from 18.86+3.79 to 26.73+4.73 mmHg during Valsalva, (P<0.0001). The anterior chamber angle recess narrowed from 16.62+6.24 to 6.5+4.02 degrees (P<0.0001). There was a significant increase in the thickness of the ciliary body from 0.92+0.25 to 1.17+0.31 mm (P=0.0006) and in the iris thickness from 0.47+0.17 to 0.57+0.11 mm (P=0.007). A significant increase in pupillary diameter (P=0.008) and a decrease in the angle opening distance (P<0.0001) also occurred during Valsalva, whereas there was no significant change in the anterior chamber depth (P=0.056). The angle recess during Valsalva had a positive correlation with the baseline anterior chamber angle (r=0.41, P=0.05) and a negative correlation with the ciliary body thickness (r=-0.52, P=0.046).CONCLUSIONS: The induction of Valsalva maneuver in day-to-day activities can lead to significant anterior segment angle shallowing and can lead to progression from the PAC stage to primary angle closure glaucoma in such predisposed eyes. The presence of a patent laser iridotomy may not prevent irido trabecular apposition during the Valsalva maneuver.     

Correlation between different measurements within the eye relative to phakic intraocular lens implantation

PURPOSE: To obtain measurements of the white-to-white distance and the anterior chamber and ciliary sulcus diameters in phakic human eyes obtained post-mortem to find a correlation between these measurements. SETTING: David J. Apple, MD Laboratories for Ophthalmic Devices Research, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. METHODS: Twenty-two phakic human eyes obtained from eye banks within 24 hours of death were evaluated. The following measurements were performed: white-to-white distance, anterior chamber diameter with a plastic sizer after a small limbal incision, and anterior chamber and ciliary sulcus diameters after fixation and sagittal section of the eyes. The first 10 eyes were studied at the 6 o'clock to 12 o'clock meridian and the last 12 eyes, at the 3 o'clock to 9 o'clock meridian. RESULTS: A positive correlation was found between the white-to-white measurements and the anterior chamber diameter in the 10 eyes studied at the 6 o'clock to 12 o'clock meridian but not in the 12 eyes studied at the 3 o'clock to 9 o'clock meridian. The latter is the meridian frequently used by surgeons to perform white-to-white measurements and thus choose the overall size of the phakic intraocular lens to be implanted. No correlation was found between the white-to-white measurements and the ciliary sulcus diameter in the 2 meridians. CONCLUSION: Experimental studies using cadaver eyes are helpful in evaluating sizing techniques for phakic IOL implantation as well as in better understanding the anatomical relationships between ocular structures.     

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.     

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.