2011 3 17 r4 vs n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
2011/3/17 R4 雷小蕾 /VS 張雪麗 PowerPoint Presentation
Download Presentation
2011/3/17 R4 雷小蕾 /VS 張雪麗

Loading in 2 Seconds...

play fullscreen
1 / 24

2011/3/17 R4 雷小蕾 /VS 張雪麗 - PowerPoint PPT Presentation


  • 51 Views
  • Uploaded on

EBM review: ANGLE CLOSURE GLAUCOMA: A MECHANISTIC REVIEW MONISHA E. NONGPIURA, JUDY Y.F. KUA AND TIN AUNGA,B CURRENT OPINION IN OPHTHALMOLOGY 2011,22:96–101. 2011/3/17 R4 雷小蕾 /VS 張雪麗. Risk factors for angle closure: recent findings. (1) Anatomical factors:

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about '2011/3/17 R4 雷小蕾 /VS 張雪麗' - hana


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
2011 3 17 r4 vs

EBM review:ANGLE CLOSURE GLAUCOMA: A MECHANISTIC REVIEWMONISHA E. NONGPIURA, JUDY Y.F. KUA AND TIN AUNGA,BCURRENT OPINION IN OPHTHALMOLOGY 2011,22:96–101

2011/3/17 R4 雷小蕾/VS張雪麗

risk factors for angle closure recent findings
Risk factors for angle closure: recent findings

(1) Anatomical factors:

(a) Anterior chamber – width, area and volume.

(b) Iris – thickness, area, and curvature.

(c) Lens – lens vault.

(2)Altered physiology/ dynamic factors:

(a) Iris – changes in volume with dilation.

(b) Choroid – choroidal expansion/effusion

altered physiology dynamic factors
Altered physiology/dynamic factors

Iris volume changes with dilation

  • Recently, it was proposed that

dynamic physiological factors

also play a significant role in

the pathogenesis of angle closure

glaucoma

AS-OCT: pupil diameter greater

in dark (a)

slide4

Iris cross-sectional area decreases with pupil dilation and its dynamic behavior is a risk factor in angle closure. Glaucoma 2009; 18:173–179.

  • Quigley et al.

evaluated changes in iris cross-sectional area measured with AS-OCT in 65 glaucoma patients, including both open angle and angle closure, during physiological and pharmacological mydriasis.

slide5

4% loss in calculated iris volume per 1mm increase in pupil size, with peak loss complete in 5 s.

Glaucoma 2009; 18:173–179.

slide6

Anatomical risk factors such as axial length, refraction,gonioscopy and corneal curvature were notdeterminants of iris cross-sectional area or change in iris cross-sectional area with pupil dilation

  • angle closure: lost less iris volume compared with controls during dilation (P=0.008).

=> this dynamic behaviour is due to movements of extracellular fluid between the iris stroma and the anterior chamber.

slide7
Optical coherence tomography quantitative analysis of iris volume changes after pharmacologic mydriasis. Ophthalmology 2010; 117:3–10.
  • the iris volume of fellow eyes of those with a history of acute primary angle closure(APAC) and age and sex-matched controls, was directly measured using AS-OCT predilation and postdilation.
  • Prior to dilation, the iris volume were similar between fellow eyes and controls (P<0.1).
  • Thirty minutes post dilation, the mean iris volume in the fellow eyes increased (P<0.01), whereas those of the controls decreased (P<0.01).
slide8

Figure 2. Examples of 8 cross-sectional images of the iris at 0-, 45-, 90-,

135-, 180-, 225-, 270-, and 315-degree meridians under illumination and

after pupil dilation (1% tropicamide) in (A, B) open-angle eyes and (C) fellow eyes. Iris volume changes from (A) 45.99 to 35.73 mm3 (23.3%), (B) 44.34 to 37.43 mm3 (16.6%), and (C) 44.39 to 50.19 mm3 (9.1%).

Note that pupil dilation seems to be comparable in the 3 eyes; by contrast,

the iris seems to be thicker in the fellow eye.

Ophthalmology 2010; 117:3–10.

slide9

biometric risk factors did not change significantly during mydriasis (P>0.1).

  • Significant predictors of a greater increase in iris volume postdilation included fellow eyes with a greater iris volume (P=0.008), brown eyes (P=0.01), and larger pupil diameter (P=0.02)

=>This dynamic iris behaviour may be a physiological adaptation to dilation to avoid blockage of the drainage angle.

slide10

Thus this inherent tendency to lose less or even gain volume during dilation, in eyes at risk of APAC, is possibly a contributing factor in the development of angle closure and may provide an alternative explanation for the higher incidence of angle closure among certain populations.

choroidal expansion effusion
Choroidal expansion/effusion
  • The choroid: highly vascular structure with variable

thickness regulated by various parameters

  • Choroidal effusion (or uveal or ciliochoroidal effusion) :abnormal accumulation of fluid in the suprachoroidal space due to an imbalance of pressure differentials
slide12

Possible mechanisms of primary angle- closure and malignant glaucoma. J Glaucoma 2003; 12:167–180.

  • Quigley et al. : choroidal expansion is another mechanism for angle closure and may precede

and even precipitate APAC.

  • no trans-vitreous resistance: any choroidal expansion would be balanced by increasing aqueous outflow, without iris or lens movement.
slide13

vitreous has a limited capacity to transmit fluid: anterior movement of the compressed vitreous, iris and lens when trans-vitreous flow is restricted

  • In small eyes predisposed to angle closure, choroidal expansion leading to increased vitreous cavity pressure, may be a contributing cause
uveal effusion in primary angleclosure glaucoma ophthalmology 2005 112 413 419
Uveal effusion in primary angleclosure glaucoma. Ophthalmology 2005; 112:413–419.
  • Sakai et al. :investigated the prevalence of choroidal effusion using UBM in 501 Japanese individuals with primary angle closure (PAC).
  • 70 acute and fellow PAC eyes, and 431 chronic PAC

eyes.

slide15

choroidal effusion in acute PAC (58%) >chronic PAC (9%) > POAG (1.3%).

  • more frequent in acute PAC eyes than in fellow eyes (23%).
  • The ACD in phakic chronic PAC eyes with choroidal effusion was significantly shallower compared with eyes without effusion (P=0.019).
slide16

Within the acute PAC group though, there were no differences in the demographics and management profile between those with and without choroidal effusion.

slide17

Confirmation of uveal effusion in eyes with primary angle closure glaucoma: an ultrasound biomicroscopy study. Arch Ophthalmol 2008; 126:1647–1651.

  • In a Singaporean population, Kumar et al: the presence of choroidal effusion among 28 newly diagnosed PACG, 42 established PACG, and 12

APAC individuals.

  • Choroidal effusion: PACG (15.7%), APAC (25%), and newly diagnosed PACG patients prior to LPI (14.2%)
  • Two weeks after LPI, the effusion resolved in half of those with newly diagnosed PACG (7.1%).
slide18

The level of effusion : milder among PACG (all grade 1 effusion) vs APAC (grade 2 or 3).

  • In contrast to Sakai et al., they did not demonstrate a significant difference in ACD between those with and without effusion.
grading of the uveal effusion
Grading of the uveal effusion

grade 0:none

grade 1:slitlike(supraciliary space less than half the ciliary body thickness)

grade 2: bandlike (supraciliary space greater than half the ciliary body thickness)

grade 3: obvious (supraciliary space greater than the ciliary body thickness).

grade 1

grade 3

Confirmation of uveal effusion in eyes withprimary angle closure glaucoma: an ultrasound biomicroscopy study. Arch

Ophthalmol 2008; 126:1647–1651.

slide20

The presence of choroidal effusion in untreated eyes raises the question of whether it is a cause or effect of PACG/APAC.

  • effusion was more severe and more prevalent in APAC =>a significant role in the pathogenesis of APAC
  • a multilevel physiological trigger may initiate a sustained choroidal expansion, which in an anatomically predisposed eye, leads to APAC and PACG.
slide21

other investigators have failed to demonstrate significant changes in biometry (ACD, lens position, RLP) before and 2 weeks after LPI=> challenges the theory of anterior lens movement secondary to choroidal expansion as a possible mechanism for APAC.

Br J Ophthalmol 2005; 89:288–290.

  • In the future, use of UBM to detect effusion could potentially be important as a predictive test in anatomically predisposed eyes (smaller eyes, narrow angles), to identify those at higher risk of developing APAC or PACG
conclusion
Conclusion
  • The identification of several novel risk factors in eyes with angle closure -> heterogeneous disease which can be caused by either one, or a combination of absolute or relative deviations in anatomical and/or physiological changes of both the anterior and posterior segment structures.
  • Evaluation of the different factors will assist population screening, help clinicians to identify the predominant mechanisms causing the angle to close, and aid in deciding the appropriate therapy.
slide23

early detection by effective screening and appropriate prophylaxis, angle closure glaucoma is a potentially preventable disease.

.