Financial disclosure: none Primary angle closure (PAC) - - PDF document

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May 12, 2023 259 likes •413 views

Ying Han, MD, PhD Associate Professor of Ophthalmology Glaucoma Service UCSF Financial disclosure: none Primary angle closure (PAC) Pathogenesis: Pupillary block and anterior lens movement Most common cause Normal pressure gradient

SLIDE 1

Ying Han, MD, PhD Associate Professor of Ophthalmology Glaucoma Service UCSF

Financial disclosure: none

SLIDE 2

Primary angle closure (PAC) Pathogenesis:

 Pupillary block and anterior lens movement

 Most common cause  Normal pressure gradient between AC and PC: ~0.23

mmHg (Heys et al. 2001).

 Lens movement: phacomorphic glaucoma, Loose

zonules in PXE

SLIDE 3

Pathogenesis

 Angle crowding

 Plateau iris configuration/syndrome  Choroidal contribution

Primary angle closure glaucoma

 PACG is estimated to affect ~26% of the glaucoma

population

 PACG is responsible for ~ 50% the cases of glaucoma‐

related blindness in the world (Quigley 1996; Quigley & Broman

2006).

SLIDE 4

Risk factors

 Age:

 prevalence of PACG: 0.02% for 40–49 years old  Prevalence: 0.95% for those > 70 years old (Day et al. 2012)

 Gender:

 women is approximately 3 times higher than in men

(Foster et al. 1996, 2000; Quigley & Broman 2006)

 Ethnicity: Asian  Refractive error: hyperopia is common  Family history and Genetic predisposition

a - Uveal meshwork b - Corneoscleral meshwork c - Schwalbe line d - Schlemm canal e - Collector channels f - Longitudinal muscle of ciliary body g - Scleral spur Schwalbe line Schlemm canal Trabeculum Scleral spur Iris processes

Diagnosis ‐ Gonioscopy

SLIDE 5

Diagnosis ‐ OCT

 Anterior segment OCT: Visante  swept‐source OCT:

 reproducible, quantifiable information on angle structure

across 360 deg

 possible to differentiate appositional from PAS by varying

lighting conditions

Diagnosis ‐ UBM

 Has better view beyond iris: plateau iris

ciliary body cysts ciliary body tumors ciliary effusions

SLIDE 6

Treatment for PACS

 How to treat PACS (primary angle closure suspect)

 LPI vs no LPI?  Cataract vs no cataract?  Is it safe to observe?

Goal of laser peripheral iridotomy (LPI)

 To reduce the risk of acute attacks  To reduce the risk of PAC/PACG  To lower intraocular pressure (IOP)

Creates a “bypass” for fluid,

eliminates pupillary block, helps “open the angle”

Settings for YAG laser
Triple burst of 8 mJ
Additional 8 mJ single shots to

enlarge

SLIDE 7

Natural history (PACS)

 Untreated eye:

 PACS to PAC varies from 13 to 35%

 Among 129 mostly European‐derived subjects, with 6 years

followed up (mean = 2.7 years), 13% were converted to PAC, 6% developed acute attack. (Wilensky JT, 1997)

 In an India population, 22% (11/48) were converted to PAC in 5

years (Thomas 2003)

 In Eskimos, 35% (7/20) were converted 10 years

Natural history (PACS)

 Treated eye:

 In an India population: 0% (0/27) progressed from PACS

to PAC or PACG over an average 4‐year follow‐up (Pandav et

al. 2007 )

 In Vietnamese: 22% (53/239) progressed to PAC over 10

years (Peng et al. 2011).

SLIDE 8

ZAP trial

 Zhongshan Angle Closure Prevention Trial

 Aims to clarify the value of LPI as a preventative

measure in PACS.

 Compares LPI versus no treatment across 870 patients

with PACS

 Follow up: 3 years for signs of increased IOP, formation

f synechiae, and instances of acute angle closure

 Angle width of treated eyes increased markedly

after LPI, remained stable for 6 months, and then decreased significantly by 18 months after

LPI. Untreated eyes experienced a more

consistent and rapid decrease in angle width

ver the same time period.

SLIDE 9

 The annual rate of change in angle width was equivalent

to 1.2°/year (95% confidence interval [CI], 0.8–1.6) in treated eyes and 1.6°/year (95% CI, 1.3–2.0) in untreated eyes (P<0.001).

Complications of LPI

 Spaeth et al reported visual symptoms after LPI in 9%

f eyes with completely covered LPI, in 26% with

partially covered LPI, and 17.5% with fully exposed LPIs.

 Hyphema, inflammation, endothelial cells injury,

cataract

SLIDE 10

 Neither visual acuity nor straylight score differed between

the treated and untreated eyes among all treated persons, nor among those with LPI partially or totally uncovered.

 Prevalence of subjective glare did not differ significantly

between participants with totally covered LPI (6.61%), partially covered LPI (11.6%), or totally uncovered LPI (9.43%).  LPI is safe regarding measures of straylight and visual

symptoms.

 It provides strong evidence that LPI for narrow angles

would be unlikely to result in important medium‐term visual disability (18 months follow‐up).

SLIDE 11

Shall we do LPI for PACS?

 LPI may slow down the rate of angle narrowing  But what is the rate of acute angle closure or PAC/PACG

converter in each group in ZAP trial?

 889 individuals were randomly (889 treated and 889

untreated eyes)

 The primary outcome was elevation of intraocular pressure,

peripheral anterior synechiae, or acute angle‐closure during 72 months of follow‐up

 Incidence of the primary outcome was 4∙19 per 1000 eye‐

years in treated eyes compared with 7∙97 per 1000 eye‐years in untreated eyes. A primary outcome event occurred in 19 treated eyes and 36 untreated eyes.

SLIDE 12

 … In view of the low incidence rate of outcomes that

have no immediate threat to vision, the benefit of prophylactic laser peripheral iridotomy is limited; therefore, widespread prophylactic laser peripheral iridotomy for primary angle‐closure suspects is not recommended...

 Exclusion criteria included

 severe health problems resulting in a life expectancy of

less than 1 year

 previous intraocular surgery or penetrating eye injury  Media opacity preventing laser peripheral iridotomy  Best corrected visual acuity worse than 20/40  An intraocular pressure increase greater than 15 mm Hg

after dilation or after a 15min dark room prone provocative testing.

SLIDE 13

Special population

 Medication is required that may provoke pupillary block  The patient has symptoms suggestive of intermittent angle

closure

 The patient's health status or occupation/avocation makes it

difficult to access immediate ophthalmic care

 The patient is poorly compliant with follow‐up  The contralateral eye of the eye with acute attack  The patients with positive provocative tests

Cataract extraction

 PACS and cataract

 Yes!

 PACS without cataract:

 The role of clear lens extraction is not clear for patients with

PACS

 LPI vs observation vs clear lens extraction: need to discuss the

risk and benefit of each treatment option with the patient.

SLIDE 14

Treatment for PAC/PACG

 How to treat PAC and PACG (primary angle

closure, primary angle closure glaucoma)

 Cataract surgery significantly lower IOP in

patients with PAC/PACS

 LPI vs clear cataract?  Any needs for a combined cataract and glaucoma

surgery

Summary

 The role of LPI in treating PACS is still debating.  Cataract extraction plays significant role in treating

PACS/PAC/PACG

 may be considered as first‐line option.