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

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 between AC and PC: ~0.23 mmHg (Heys et al. 2001) .  Lens movement: phacomorphic glaucoma, Loose zonules in PXE

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) .

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

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 effusions ciliary body tumors

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

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) .

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 of 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 over the same time period.

 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% of eyes with completely covered LPI, in 26% with partially covered LPI, and 17.5% with fully exposed LPIs.  Hyphema, inflammation, endothelial cells injury, cataract

 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).

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.

 … 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...  E xclusion 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.

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.

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.