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JOURNAL ABSTRACTS
Year : 2011  |  Volume : 59  |  Issue : 1  |  Page : 75-78

Changing concepts of angle closure glaucoma: A review


Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences (AIIMS), New Delhi, India

Date of Web Publication16-Dec-2010

Correspondence Address:
Rajesh Sinha
S-7, R. P. Centre, AIIMS, New Delhi - 110 029
India
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Source of Support: None, Conflict of Interest: None


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How to cite this article:
Sinha R, Kumar G, Bali SJ, Dada T. Changing concepts of angle closure glaucoma: A review. Indian J Ophthalmol 2011;59:75-8

How to cite this URL:
Sinha R, Kumar G, Bali SJ, Dada T. Changing concepts of angle closure glaucoma: A review. Indian J Ophthalmol [serial online] 2011 [cited 2022 Jul 3];59:75-8. Available from: https://www.ijo.in/text.asp?2011/59/1/75/73709

It is an established fact now that primary angle closure glaucoma (PACG) is more common in the Asian population and accounts for greater blindness than primary open angle glaucoma (POAG). With the advent of ultrasound biomicroscopy (UBM) and anterior segment ocular coherence tomography (AS-OCT), mechanisms of angle closure are better understood. This article reviews the published literature that gives insight into the current concepts related to the topic.


  Terminology Top


Lowe et al. (Br. J Ophthalmol 1964;48:544-50) used the term "creeping angle closure" to describe a large subset of patients in whom peripheral anterior synechiae (PAS) slowly advances forward circumferentially, causing the iris insertion appear to become more and more anterior.

Ritch et al. (Surv. Ophthalmol 1996;41:31-6) described the signs and gonioscopic appearance of appositional angle closure. They used the term occludable angle to describe narrow angles accompanied by (1) appositional closure; (2) objective evidence of past closure, such as PAS or small segment of heavily pigmented meshwork; (3) history of past closure; and (4) a positive provocative test.

Foster et al. (Br J Ophthalmol 2002;86:238-4) described the scheme for classification of primary angle closure (PAC) in population-based epidemiologic surveys. They classified angle closure into (1) primary angle closure suspect (PACS): eyes with appositional contact between the peripheral iris and posterior trabecular meshwork; (2) PAC: eyes with occludable drainage angles and features indicating that trabecular obstruction by the peripheral iris has occurred, such as PAS, elevated intraocular pressure, iris whorling (distortion of the radially orientated iris fibers), "glaucomflecken" lens opacities, or excessive pigment deposition on the trabecular surface. The optic disc does not have glaucomatous damage; and (3) PACG: PAC together with evidence of glaucoma.


  Epidemiology Top


Quigley et al. (Br J Ophthalmol 1996;80:389-93) published that the mean age-adjusted prevalence of POAG in European population was 2.42%. The prevalence of angle closure glaucoma (ACG) averaged 0.2 % in those over 40 years of age. They concluded that 66.8 million people had open angle glaucoma (OAG) and ACG in nearly equal numbers, and whereas the majority of ACG was in Asia, OAG was more equally distributed.

Jacob et al.(Indian J Ophthalmol 1998;46:81-6) (Vellore Eye Study) studied an urban South Indian population and reported a prevalence of 4.1 and 43.2 of POAG and PACG, respectively, per 1000 population.

Dandona et al. (Ophthalmology 2000;107:1710-6) (Andhra Pradesh Eye Disease Study) estimated the prevalence of PACG and occludable angles to be 1.08% (95% confidence interval [CI]: 0.36-1.8) and 2.21% (95% CI: 1.15-3.27) in participants of 40 years or older. The females were found to have a higher prevalence of the same (odds ratio: 1.7).

Ramakrishnan et al. (Ophthalmology 2003;110:1484-90) (The Aravind Comprehensive Eye Survey) conducted a population-based cross-sectional study in 5150 subjects 40 years and older from 50 clusters representative of 3 southern districts of Tamil Nadu. They reported that the prevalence (95% CI) of any glaucoma was 2.6% (2.2-3.0); POAG was 1.7% (1.3-2.1); PACG was 0.5% (0.3-0.7); and secondary glaucoma excluding pseudoexfoliation was 0.3% (0.2-0.5).

Rahman et al. (Br J Ophthalmol 2004;88:1493-7) studied the clinical profile and prevalence of glaucoma in Dhaka. They noted that POAG was the most common form of glaucoma accounting for 75% of glaucoma cases. About 20% of people with POAG were noted to be blind, compared with 33.3% of those with secondary glaucoma. PACG was reported to be the most visually destructive form of glaucoma.

Raychoudhari et al. (Br J Ophthalmol 2005;89:1559-64) (West Bengal Glaucoma Study) studied 1594 people 50 years and older in 9 villages. They reported that the age-standardized estimate for the prevalence of all glaucoma in people older than 50 years was 3.4%. They suggested that PACG may be less prevalent in Bengalis than in Indian populations living in South India with a crude ratio of POAG to PACG of more than 10:1.

Ichhpujani et al. (Indian J Ophthalmol 2010;58(3):199-203) studied 814 patients with ACG and found that mean age at presentation was significantly higher for males (57.57 ± 11.62 years) as compared to females (53.64 ± 10.67 years). PACG was found to be the most frequently diagnosed subtype (49.38%), followed by PAC (39.68%) and PACS (10.93%).

Senthil et al. (Ophthalmology 2010;117:1729-35) (Andhra Pradesh Eye Disease Study) estimated prevalence of PACS, PAC, PACG, and associated factors in Andhra Pradesh. The reported prevalence rates (95% CI) of PACG, PAC, and PACS were 0.94% (0.63-1.24), 0.3% (0.1-0.5), and 2% (1.5-2.3), respectively. They reported that 20% of the blindness was attributable to PACG. Increasing age, increasing intraocular pressure (IOP), diabetes mellitus, and female gender were found to be significantly associated with angle closure.


  Mechanism of Angle Closure Top


Pupillary block

Barkan et al. (Am J Ophthalmol 1951;34:567-71) found that air injected into the anterior chamber (AC) caused a sharp rise in IOP, which is attributable to the obstruction of the aqueous flow from the posterior to the AC, as a result of a valve-like action between the anterior surface of the iris and the posterior surface of the air bubble.

Trabecular meshwork dysfunction

Sihota et al. (Indian J Ophthalmol 2001;49:255-9) studied trabecular specimens from acute and chronic angle closure patients by light and electron microscopy. They noted that pigment accumulation in the trabecular spaces and within the cells; and non-inflammatory degeneration were the primary changes in the trabecular meshwork after acute ACG. In chronic PACG eyes, there was evidence of loss of endothelial cells and reactive repair processes in areas away from visible PAS. They concluded that a gonioscopic evaluation of the extent of PAS alone may not reflect the extent of trabecular meshwork damage in acute and chronic PACG.

Peripheral anterior synechiae

Aung et al. (Ophthalmology 2005;112:28-32) investigated the relationship between drainage angle configuration and optic disc cupping in subjects with chronic ACG in a randomized controlled trial. They concluded that in subjects with chronic ACG, the extent of PAS and a narrower width of the drainage angle were associated with higher untreated IOP and a larger vertical cup-to-disc ratio. They reported that there was a 0.39 mmHg increase in baseline untreated IOP for each unit increase in clock hours of PAS.

Plateau iris

Barkan et al. (Am J Ophthalmol 1954;37:332-50) noted that some cases have shallow angle with deep central AC. This configuration was found in 20% of his angle closure patients, which was later on described as plateau iris.

Pavlin et al. (Am J Ophthalmol 1992;113:390-5) first described the UBM findings of plateau iris. They suggested that the anteriorly placed or anteriorly rotated ciliary body pushed iris periphery from posterior side and prevented iris from falling back even after peripheral iridectomy.

Garudadri et al.(J Glaucoma 2002;11(6):502-7) reported that plateau iris was common in Indian population. They concluded that anteriorly directed ciliary processes were seen both in eyes with plateau iris and in eyes with PACG that had deep ACs after iridotomy.

Kumar et al.(Ophthalmology 2008;115(3):430-4) defined plateau iris in an eye by the presence of the following features in at least 2 quadrants: the presence of an anteriorly directed ciliary body; an absent ciliary sulcus; a steep iris root from its point of insertion followed by a downward angulation from the corneoscleral wall; presence of a central flat iris plane; and irido-angle contact. They reported that plateau iris was seen in 54 of 167 (32.3%) PACS eyes after laser peripheral iridotomy (LPI) and was most commonly observed in the superior and inferior quadrants.

Kumar et al.(Arch Ophthalmol 2009;127:1269-72) highlighted the importance of nonpupillary block mechanisms in Asian individuals. About 30% of PACG eyes with a patent LPI were noted to have plateau iris on UBM. They noted that in eyes with PACG, the prevalence rates of plateau iris were 32.8% and 31.7% in Singapore and Thailand populations, respectively.

Role of lens

Lowe et al. (Am J Ophthalmol 1969;67:87-93) reported that a shallow AC is related to the age-related increase in lens thickness and more anterior position of the lens. They estimated that increased lens thickness caused 0.35 mm of shallowing of AC, and forward lens position causes 0.65 mm of shallowing.

Lim et al. (Korean J Ophthalmol 1992;6:19-31) noticed that the decrease in AC depth is accelerated in women between the fourth and fifth decades due to age-related increase in lens thickness, which may explain the greater propensity for PAC in elderly females.

Friedman et al. (Ophthalmology 2003;121:633-42) reported that contralateral eyes of individuals having an acute angle closure (AAC) attack tended to be shorter and have more crowded anterior segments than those of healthy controls. They also noted that differential reactions to luminance changes and pilocarpine therapy were associated with an AAC attack.

Role of anterior segment optical coherence tomograph

Dada et al.(J Cataract Refract Surg 2007;33:837-40) reported that measurement of anterior segment parameter by UBM and AS-OCT gave comparable results. They found an excellent correlation between AS-OCT and UBM measurements for the nasal angle (r = 0.84; P < 0.0001), temporal angle (r = 0.86; P < 0.0001), anterior chamber depth (ACD) (r = 0.97; P < 0.0001), and central corneal thickness (r = 0.91; P < 0.0001).

Zhang et al. (Chin Med J (Engl) 2008;121:1274-79) concluded that the noncontact approach of slit lamp (SL)-OCT enables visualization of intrableb structures at any time after surgery. They reported that SL-OCT has greater sensitivity and specificity than UBM in evaluating filtering bleb function.


  Management Top


Laser peripheral iridotomy

Nolan et al. (Br J Ophthalmol 2000;84 : 1255-9) reported that LPI is an effective treatment for acute PAC, resulting in widening of the filtration angle and reduction of elevated IOP. However, they stated that iridotomy alone is less effective at controlling IOP once glaucomatous optic neuropathy associated with synechial angle closure has occurred.

Lim et al. (Ophthalmology 2004;111:1470-4) evaluated the changes in the configuration of the drainage angle in the first year after acute PAC. They noted that in acute PAC eyes, there was a significant increase in angle width from baseline to 2 weeks after LPI but no change in angle width subsequently. The fellow eyes were shown to have widening of the angle between baseline and week 2; and from week 2 to 4 months. However, no significant change was noted in PAS in either affected or fellow eyes over the follow-up period of 12 months.

Aung et al. (Am J Ophthalmol 2001;131:7-12) reported that 58.1% eyes with LPI after acute PAC continued to have elevated IOP and 32.7% eventually required trabeculectomy.

Choi et al.(Am J Ophthalmol 2005;140:1125-7) concluded that approximately 1 of 3 PACG eyes showed PAS progression during a 3-year follow-up period after LPI. They suggested that the probability of progression was found to be higher in the eyes that exhibited plateau iris and in eyes that proved to be relatively unresponsive to medication before LPI.


  Topical Medications Top


Edwards et al. (Curr Med Res Opin 1997;13:501-9) compared Ocusert Pilo 40, intensive pilocarpine, and low-dose pilocarpine in the initial treatment of primary acute ACG. They noted that over the treatment period of 2 h, a comparable reduction in IOP was seen in the Ocusert-treated, the intensive pilocarpine-treated, and the low-dose pilocarpine-treated groups.

Aung et al. (Ophthalmology 2000;107:1178-83) compared IOP-lowering effects of 0.005% latanoprost once daily and 0.5% timolol twice daily in chronic ACG patients. They suggested that latanoprost may be a therapeutic choice for the medical treatment of chronic PACG. In a double-masked study on 32 patients, IOP after 2 weeks of treatment was reduced by 8.8 mmHg in the latanoprost group, compared with 5.7 mmHg in the timolol group (P =0.04).

Hung et al. (J Ocul Pharmacol Ther 2000;16:43-7) concluded that latanoprost 0.005% was effective as an adjunct to medical therapy for residual angle closure after iridectomy. In 26 PACG eyes with persistently elevated IOP on conventional IOP-lowering drugs (beta-blockers and pilocarpine) after iridectomy, IOP was <20 mmHg in all eyes at 1-year follow-up after the addition of latanoprost 0.005% as an adjunctive therapy.


  Argon Laser Peripheral Iridoplasty Top


Lam et al. (Ophthalmology 2002;109:1591-6) reported that argon laser peripheral iridoplasty (ALPI) is a safe and more effective alternative to conventional systemic medications in the management of acute PACG not amenable to immediate LPI. They noted that ALPI-treated group had significantly lower IOP levels than the medically treated group at 15 min, 30 min, and 1 h after the start of the treatment.

Ritch et al. (Surv Ophthalmol 2007;52:279-88) stated that ALPI is an effective modality for reducing angle crowding in nanophthalmos, PAC, lens-induced angle closure, and plateau iris configuration. It was concluded that it acts by eliminating and reducing the amount of residual appositional angle closure after LPI.

Ritch et al. (Ophthalmology 2004;111:104-8) documented long-term effect of ALPI in residual angle closure in cases of plateau iris. The angle in 20 of 23 (87.0%) eyes remained open in the entire follow-up period after only one treatment with ALPI. It was concluded that ALPI is highly effective in eliminating residual appositional closure after laser iridotomy caused by plateau iris syndrome.


  Trabeculectomy Top


Aung et al. (Ophthalmology 2000;107:1298-302) retrospectively analyzed cases with medically uncontrolled acute PAC who underwent urgent trabeculectomy. They noted that trabeculectomy in acute ACG is associated with a higher risk of failure, postoperative AC shallowing, malignant glaucoma, and a significant rate of cataract formation. Thus, they concluded that trabeculectomy may not be the procedure of choice in medically unresponsive cases of acute PAC.

Chen et al. (J Glaucoma 2009;18:679-83) compared the results of trabeculectomy in acute ACG and chronic ACG. They concluded that compared with chronic ACG, trabeculectomy may not be as good for patients of acute ACG, because it may lead to worsened visual acuity, a greater failure rate, more complications, and fewer cases of surgical survival.


  Lens Extraction Top


Hayashi et al. (Ophthalmology 2000;107:698-703) noted that the width and depth of the AC angle in eyes with ACG increased significantly after cataract extraction and intraocular lens (IOL) implantation and became similar to that in eyes with OAG and that in normal eyes, which may lead to the decrease in IOP seen in the postoperative period. It was reported that before surgery, the mean AC angle width and depth in the ACG group was less than that in either the OAG or control groups by approximately 10° in angle width and 1.0 mm in depth. Although after surgery, the width and depth in the ACG group were still smaller than that in the other groups, the differences decreased to 2° for angle width and 0.3 mm for depth.

Hayashi et al. (J Cataract Refract Surg 2001;27:1779-86) reported that cataract surgery substantially reduces IOP and the number of medications required for IOP control in POAG and PACG eyes. They noted that the cumulative survival probability of IOP control at 24 months was 91.9% in the PACG group and 72.1% in the POAG group.

Yang et al. (J Cataract and Refract Surg 1997;23:1109-13) concluded that cataract extraction with posterior chamber IOL implantation in eyes with PACG could control IOP adequately in most cases. They reported that these eyes showed a mean increase in ACD and angle width from 2.04 to 3.44 mm and attributed this to exchange of the thickened lens (5 mm) for IOL (1 mm).

Roberts et al. (J Cataract Refract Surg 2000; 26: 1012-1016) reported a case series of 3 patients with acute ACG with uncontrolled IOP after peripheral iridotomy and medications. It was concluded that primary phacoemulsification with the option of future trabeculectomy should be considered in selected patients with persistent appositional angle closure and uncontrolled IOP after an attack of ACG.

Imaizumi et al. (J Cataract Refract Surg 2006;32:85-90) reported that phacoemulsification with IOL implantation lowered IOP, improved visual acuity, and diminished the need for antiglaucoma medication in eyes with ACG and with a prior ACG treated by laser iridotomy.

Gunning et al. (J Cataract Refract Surg 1998;24:1347-56) suggested that a prior cataract procedure with the option of a future trabeculectomy may be a more attractive approach in patients with subacute or chronic ACG than trabeculectomy followed by an optional cataract procedure.

Kubota et al. (Ophthalmologica 2003;217:325-8) concluded that phacoemulsification with IOL implantation is useful in controlling IOP in ACG and added that one should take care of shallow AC, poor mydriasis and zonular weakness.

Nonaka et al. (Ophthalmology 2005;112:974-9) also reported that cataract surgery was effective to lower IOP by resolving completely the residual angle closure after iridotomy.

Nonaka et al. (Ophthalmology 2006;113:437-41) evaluated quantitatively, by means of UBM, changes in the anterior segment configuration, including the ciliary processes, induced by cataract surgery in eyes with PAC. They noted that cataract surgery resulted in not only complete dissolution of lens volume and pupillary block, but also attenuation of the anterior positioning of the ciliary processes, all of which contributed to postoperative widening of the angle in eyes with PAC.

Pachimkul et al. (J Med Assoc Thai 2008;91:303-8) concluded that phacoemulsification and IOL implantation can lower the IOP, remove pupillary block, increase angle width, relieve PAS, decrease antiglaucoma medications, and improve visual acuities in patients with ACG and cataracts.


  Phacoemulsification vs LPI for Acute PAC Top


Jacobi et al. (Ophthalmology 2002;109:1597-1603) reported that lens extraction may be considered as a better procedure than surgical iridectomy in uncontrolled ACG. The mean postoperative IOP and the mean number of ocular hypotensive medications were found to be significantly lower in the primary phacoemulsification and IOL implantation group than surgical conventional iridectomy group.

Lui et al. (Arch Ophthalmol 2006;124:1390-4) reported that the reduction of IOP 3 months after phacoemulsification is significant and is similar in extent to post-iridotomy eyes with and without glaucomatous optic neuropathy. They also reported that a higher postoperative IOP in PACG is associated with a higher preoperative IOP and with a deeper preoperative ACD.

Lam et al. (Ophthalmology 2008;115:1134-40) compared early phacoemulsification and peripheral iridotomy in acute PAC in a randomized controlled trial. It was concluded that early phacoemulsification is more effective in preventing IOP rise than LPI in patients after abortion of acute PAC.


  Phacoemulsification vs Phacotrabeculectomy Top


Tham et al. (Ophthalmology 2008;115:2167-73) in a randomized controlled trial concluded that combined phacotrabeculectomy with adjunctive mitomycin C may be marginally more effective than phacoemulsification alone in controlling IOP in medically controlled chronic ACG eyes with coexisting cataract. However, they reported that combined surgery may be associated with more complications and additional surgery in the postoperative period.

Tham et al. (Arch Ophthalmol 2010;128:303-11) conducted 2 randomized controlled trials comparing phacoemulsification with phacotrabeculectomy in medically uncontrolled chronic ACG. No significant difference was noted in visual acuity or disease progression between the 2 treatment groups. However, combined phacotrabeculectomy was noted to result in significantly more surgical complications than phacoemulsification alone in chronic ACG eyes with coexisting cataract.


  Goniosynechiolysis Top


Teekhasaenee et al. (Ophthalmology 1999;106:669-75) reported that Phacoemulsification-goniosynechiolysis and posterior chamber IOL implantation are effective in reducing PAS and IOP and improving visual acuity in eyes with persistent chronic ACG when performed within 6 months after treatment for acute ACG.


  Long-term Outcome Top


Alsagoff et al. (Ophthalmology 2000;107:2300-4) studied the long-term clinical course of ACG in a retrospective study. It was concluded that despite the presence of a patent LPI, most eyes with established PACG required further treatment to control IOP. They also added that medical therapy fails in most cases, necessitating filtering surgery.

Rosman et al. (Ophthalmology 2002;109:2227-31) compared the clinical course of chronic ACG in North American and Asian population. They reported that results in the American population are similar to that reported in Asian patients. Despite the presence of a patent LPI, most eyes with chronic ACG presenting with elevated IOP and having both optic disc and visual field (VF) damage in both populations required further treatment to control IOP.

Ang et al. (Ophthalmology 2004;111:1636-40) reported that the visual morbidity of PACG may be related to the finding that the asymptomatic form of the disease is visually destructive. They noted that eyes with asymptomatic PACG often present with severe to end-stage VF loss at the time of first presentation to hospital, whereas most PACG eyes with previous symptomatic angle closure present with mild or moderate VF defects.

Aung et al. (Ophthalmology 2004;111:1464-9) published long-term results in patients with acute ACG after a mean follow-up of 6.3 ± 1.5 years. They concluded that several years after being seen with acute PAC, 17.8% of subjects examined were blind in the eye with acute attack, and almost half had glaucomatous optic nerve damage.

Sihota et al. (Acta Ophthalmol Scand 2004;82:209-13) reported 6-year follow-up results of 70 patients with chronic ACG. It was noted that 65% were controlled medically throughout the 6-year follow-up period, whereas 35% required surgery. Stable VFs and good long-term IOP control were seen in 90% of chronic PACG eyes on medical/surgical therapy over 6 years.




 

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  In this article
Terminology
Epidemiology
Mechanism of Ang...
Management
Topical Medications
Argon Laser Peri...
Trabeculectomy
Lens Extraction
Phacoemulsificat...
Phacoemulsificat...
Goniosynechiolysis
Long-term Outcome

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