Ultrasound biomicroscopic imaging demonstrate thinner ciliary body thickness in eyes with angle closure

INTRODUCTION

Angle closure has been proved to be associated with specific anatomic features of the globe. Compared with normal eyes, eyes with primary angle closure (PAC) and primary angle-closure glaucoma (PACG) present biometric features of shallow anterior chamber depth, narrow angle, short axial length, thick lens and anterior lens position

. Moreover,eyes with specific peripheral iris configuration, such as plateau iris, thick iris and anteriorly inserted iris, are also associated with angle closure, including appositional angle closure after laser peripheral iridotomy (LPI)

.

Ciliary body is one of the important parts of the angle, and the biometric features of the ciliary body were proved to be related with angle closure as well. Previous studies have revealed that anterior situation of the ciliary processes is a predisposing factor of PAC/PACG

. The anteriorly situated ciliary processes are thought to be the main cause of plateau iris by pushing the iris root toward the trabecular meshwork

,and may induce thick lens and anterior lens position through loosening the zonules as well

.

Ciliary body thickness is supposed to be another potential factor for angle closure

. Gohdo

first found thinner ciliary body thickness in eyes with gonioscopic narrow but open angle (Shaffer classification, grade 0 to 2). Then similar results were also found in eyes with some special kinds of angle-closure glaucoma: thinner ciliary body thickness was found in eyes with acute primary angle closure (APAC)

,and also in eyes with malignant glaucoma

. However, there were no definite results yet about the ciliary body thickness in eyes with PAC/PACG compared to the normal ones.

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SUBJECTS AND METHODS

All images were measured by one masked observer (Chen SY), using an originally developed semiautomatic measuring software. This measuring software was improved on the basis of UBM PRO 2000 software (Paradigm Medical, Salt Lake City, UT, USA). The following parameters were measured as previously described

(Figure 1): 1) the ciliary body thickness at the position of 1 mm posterior to the scleral spur(CBT1); 2) the trabecular-ciliary process distance (TCPD)defined as the length of the line extending from the corneal endothelium 500 μm from the scleral spur perpendicularly through the posterior surface of the iris to the ciliary process;3) the trabecular-ciliary process angle (TCA) measured with the scleral spur as the apex, and the corneal endothelium along with the anterior surface of ciliary process as the two arms of the angle.

UBM examination was performed with a UBM (model P45, Paradigm Medical, Salt Lake City,UT, USA) equipped with a 50-MHz transducer probe allowing 5.0×5.0 mm

field of view and approximately 50 μm spatial resolution. All subjects were examined in the supine position in a dark room (illumination ＜1 lx, measured with an ST-92 luminance meter; Beijing Teachers University Photoelectricity Instrument Factory, Beijing, China). After topical anaesthesia,the globe was placed with an eyecup filled with hydroxyethyl cellulose as a coupling agent. Subjects were instructed to relax and focus on a fixation target about 1 m in front of the eyes to avoid the effect of accommodation. Each eye was examined in the way of radial scan through the centre of the pupil, and images of the 3, 6, 9, 12 o’clock were obtained to represent each quadrant respectively.

從理論上講，汽油發動機尾氣排氣成分主要有碳氫化合物(HC)、一氧化碳(CO)、二氧化碳(CO2)和氮氧化合物(NOx)4種成分組成，其中有害物質主要有碳氫化合物(HC)、一氧化碳(CO)、氮氧化合物(NOx)。通過三元催化的氧化還原反應后，碳氫化合物變成水和二氧化碳，一氧化碳變成二氧化碳和氮。為了更好地達到氧化還原效果，需要汽油與空氣完全燃燒，且沒有殘留氧氣的理論空燃比為14.7∶1。利用空燃比反饋就是要將這一比例無限精確，才能保證三元催化轉化器的轉化效率最高。

Normal control subjects were consecutively recruited from general ophthalmologic clinic of Peking University Third Hospital between January 2009 and December 2009. The inclusion criteria for normal subjects included: 1) age between 40 and 80y; 2) willing and capable to attend this study. And one was excluded if presenting any intraocular diseases(including PAC/PACG, except for mild cataracts and refractive error with the spherical equivalent within -8 D and 4 D), or having previous intraocular surgery or laser treatment history,or any other condition conforming to the exclusion criteria for the PAC/PACG group.

After excluding images of quadrants with PAS, 110 non-PAS images randomly selected from the matched two groups were measured, and the PAC/PACG group also showed the same features (Table 3). Moreover, the distributions of non-PAS images among the four quadrants were agreed in the two groups (Chi-square test,

=0.933).

This was a cross-sectional comparative study consisting of two groups: PAC/PACG patients and normal subjects. This study was performed at the Peking University Third Hospital, Peking University Eye Centre by 5 clinicians, including 2 full-time attending glaucoma specialists (Wu LL, Fan X) and 3 glaucoma fellows (Chen SY, He N, Yan YJ). Patients with PAC/PACG were consecutively enrolled in this study who underwent LPI at the glaucoma clinic of Peking University Third Hospital between January 2009 and December 2009. The inclusion criteria included: 1) age between 40 and 80y; 2) conformed to the diagnostic criteria of PAC/PACG. The diagnostic criteria of PAC were defined as follows

: an eye with an occludable drainage angle (an angle in which ≥270 degree of the posterior trabecular meshwork could not be seen with static gonioscopy) and features that indicated trabecular obstruction by the peripheral iris had occurred, such as peripheral anterior synechia (PAS), elevated intraocular pressure (IOP), or excessive pigment deposition on the trabecular surface, and without glaucomatous damage to the optic disc. While PACG was defined as presence of glaucomatous optic neuropathy(such as loss of neuroretinal rim with a vertical cup-to-disc ratio of ＞0.7 and/or notching with nerve fibre layer defect) with corresponding visual field loss on the basis of the diagnosis of PAC. Patients were excluded if any of the following conditions present: 1) secondary angle closure, such as neovascularization of the iris, uveitis, trauma, tumour, lens intumescence or subluxation; 2) any other ocular diseases (except for mild cataracts and refractive error with the spherical equivalent within -8 D and 4 D) or previous intraocular surgery; 3) unable to perform contact examination such as gonioscopy or UBM;4) sustained pilocarpine or prostaglandin administration which might affect ciliary body morphology

; 5) eyes with more than two quadrants of PAS and uncontrolled IOP with medications, which indicated for the filtration surgery; 6) acute attack history which might lead obvious uveal effusion

or pupil distortion and iris whirling.

The study followed the tenets of the Declaration of Helsinki and was approved by the Institutional Review Board of Peking University Third Hospital. Signed informed consent was obtained from each subject involved in this study.

The measurement patterns by the software were presented in Figure 2. The semiautomatic measuring procedure was completed as follows: 1) randomly select one image for measurement; 2) mark the sclera spur by the observer and two circles centred on the sclera spur with radius of 500 μm and 1 mm were automatically drawn; 3) mark point A which is the intersection of the smaller circle and the inner surface of the cornea, then draw a line along the posterior surface of the iris and get a perpendicular line to iris through point A automatically, and mark the intersection of the perpendicular line and the anterior surface of the ciliary processes as point C; 4) mark point B as the intersection of the bigger circle and the outer surface of the ciliary body, and get a perpendicular line to line BO automatically, and then mark point E as the intersection of the perpendicular line and inner surface of ciliary body; 5) mark point F to make line OF the tangent lineof the anterior surface of the ciliary processes; 6) measure distances AC, BE, and angle AOF as TCPD, CBT1 and TCA,and then save the data automatically.

電力設計企業的核心競爭力是人才，支持PPP業務的發展需要PPP專業人才，電力設計企業應提前儲備PPP專業人才，從而搶灘PPP市場。儲備人才包括引進和培養兩種模式，因為PPP是新領域，專業人才緊缺，引進人才不僅成本高昂，還可能水土不服，所以電力設計企業應重點從內部挖掘、培養人才，通過創新培養體系，注重理論與實踐結合，邀請實戰派專家進行……