Angle-closure Glaucoma: The Role of the Lens in the Pathogenesis, Prevention, and Treatment

doi:10.1016/j.survophthal.2008.12.002

Survey of Ophthalmology

Volume 54, Issue 2, March–April 2009, Pages 211-225

https://doi.org/10.1016/j.survophthal.2008.12.002 Get rights and content

Abstract

Primary angle-closure glaucoma is a major cause of blindness worldwide. It is a disease of ocular anatomy that is related to pupillary-block and angle-crowding mechanisms of filtration angle closure. Eyes at increased risk for primary angle-closure are small with decreased axial length, anterior chamber depth, and filtration angle width, associated with a proportionately large lens. Angle-closure glaucoma afflicts Asian and Eskimo eyes more frequently than eyes in other races with similar predisposing dimensions. The treatment of primary angle closure addresses its causal mechanisms. Laser peripheral iridotomy equalizes the anterior and posterior pressures and widens the filtration angle by reducing the effect of pupillary block. Argon laser peripheral iridoplasty contracts the iris stroma to reduce angle crowding and is helpful for some affected eyes. Lensectomy dramatically widens the angle and eliminates pupillary block. Clinical reports of lensectomy with posterior chamber intraocular lens implantation in the treatment of acute, chronic, and secondary angle-closure glaucoma describe very favorable results. The appropriate role for lensectomy in the management of primary angle closure, however, remains unproven. Prospective, randomized clinical trials are ongoing to determine the value and comparative risks and efficacy of lensectomy versus medical therapy, laser peripheral iridotomy, laser iridoplasty, and filtration procedures for the treatment of acute and chronic primary angle closure and for the prevention of chronic angle-closure glaucoma, both after and in place of laser peripheral iridotomy.

Introduction

Angle closure is a disorder of ocular anatomy characterized by closure of the drainage angle by appositional or synechial approximation of the iris against the trabecular meshwork, blocking its access to aqueous humor. The final common result in related disorders is an elevation of the intraocular pressure (IOP), due to the secondary impairment of aqueous humor outflow from the eye, followed by the development of glaucomatous optic neuropathy.

This review will focus on the role of the lens in the pathogenesis and treatment of primary and secondary angle closure.

Section snippets

Clinical Types of Angle-closure Glaucoma

Angle-closure disorders can be divided into primary and secondary groups. Primary angle closure includes those that are caused by pupillary block, angle crowding (from plateau iris configuration or anterior lens position) or a combination of both.⁵⁰ A classification endorsed by the American Academy of Ophthalmology subdivides the primary group into primary angle-closure suspect, primary angle closure without optic neuropathy (PAC), and primary angle-closure glaucoma with neuropathy (PACG).⁴

Epidemiology of Primary Angle-closure Glaucoma

It has been estimated that 67 million people worldwide are affected with a primary glaucoma and that one-third have PACG.⁹⁵ In European and African populations primary open-angle glaucoma (POAG) occurs approximately five times more frequently than PACG; in Chinese,20, 21 Mongolians,¹⁹ and Indians,¹⁵ however, the rates of PACG may equal or be greater than POAG. In Eskimos/Inuit the prevalence of PACG is felt to be higher than any other ethnic group.¹² A prevalence study reported PACG as

Mechanisms in Angle-closure Glaucoma

Pupillary block is the most frequent and important mechanism responsible for angle closure,14, 97 but in many cases it is not the only mechanism involved. Iris angle-crowding may co-exist with pupillary block to cause the angle closure. In the plateau iris configuration, the iris is held anteriorly by the ciliary processes, but a pupillary block component may also be present.¹³² These pathologic mechanisms exist because of primary anatomic variations in the size, position, and relationship of

Pathogenesis of Angle-closure Glaucoma and the Role of the Lens

Eyes with primary angle closure have significant anatomic differences from normal eyes.13, 75 The most significant clinical hallmarks of an eye with angle-closure are the shallow AC and narrow angle. The mean anterior chamber depth (ACD) in PAC eyes is approximately 1.8 mm, which is 1 mm shorter than in normal eyes.75, 125 Angle closure becomes a rarity when anterior chamber depth exceeds 2.5 mm.⁷⁶ Decreased AC volume,68, 79 small corneal diameter,16, 124 and short axial lengths16, 124 are all

Current Surgical Treatment Options for Primary Angle-closure Glaucoma

Understanding and caring for patients with APAC requires repetitive careful clinical ocular examinations including evaluation of the filtration angle to determine the mechanism of the angle-closure and the active stage of the disease. The treatment of a patient with acute disease should be followed by care to prevent the development or worsening of chronic angle closure glaucoma. In a patient with established synechial angle closure and advanced glaucomatous optic neuropathy (GON), active

Lens Extraction in Primary Angle-closure Glaucoma

The role of lensectomy in the management of PACG has not been established. The potential importance of this definitive procedure to correct persistent pupillary-block and angle crowding after LPI in both the treatment and prevention of acute and chronic angle closure glaucoma cannot be overestimated.

Lens Extraction for Secondary Angle-closure Glaucomas

The lens plays a significant role in the development of angle closure in other important eye conditions, which occur less frequently than PACG but in patients of all ages.⁹⁶ It is of value to appreciate that the same mechanisms of pupillary block and angle crowding, as seen in patients with PACG, also occur in these other conditions. Angle-closure develops in these conditions when the lens is disproportionately large, when the eye is abnormally small, when the lens is thickened, or when the

Conclusion

PACG is a leading cause of blindness and is potentially preventable. It is projected that 15.7 million will have ACG in 2010 and 3.9 million will be bilaterally blind from it.⁹² The lens plays an essential and pivotal role in the pathogenesis of primary and secondary ACG. Clinical studies suggest that lensectomy and PCIOL implantation for ACG patients may offer successful IOP control, and maintenance of improved vision. Lensectomy eliminates pupillary block, widens the angle to lessen angle

Method of Literature Search

A search of the PubMed database was conducted for the years 1900–2007, using the following key words: angle closure glaucoma, pupillary block, angle crowding, lensectomy, cataract extraction. Additional references were recovered from bibliographies of the references. Pertinent articles available from the medical files of the authors were also reviewed.

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One of the main causes of blindness and chronic neurological illness is Glaucoma. Retinal ganglion cells and their axons gradually start to disappear in people with glaucoma, an eye condition. In the past, high intraocular pressure (IOP) was used to describe glaucoma; however, in the last 10 years, glaucoma experts have accepted that higher IOP is the most significant risk factor for glaucoma but does not characterize the condition. The two basic subtypes are angle-closure glaucoma and open-angle glaucoma (OAG). Primary angle-closure glaucoma (PACG) and secondary angle-closure glaucoma are further classifications for angle-closure glaucoma. Primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG), and secondary OAG are the three subtypes of OAG. Recent research suggests that several interrelated pathogenetic mechanisms, including mechanical effects from elevated IOP, neutrophine supply, hypoxia, excitotoxicity, oxidative stress, and the participation of autoimmune processes, are involved in the pathogenesis of glaucoma. The innate immunity’s reaction to these autoimmune processes in the central nervous system is extremely well-organized. The objective of this study is to present the recent data on major therapeutic treatments and uses of different medications in glaucoma and other nanocarrier formulations for administering genistein to patients with different disorders.
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Major ReviewAngle-closure Glaucoma: The Role of the Lens in the Pathogenesis, Prevention, and Treatment

Abstract

Introduction

Section snippets

Clinical Types of Angle-closure Glaucoma

Epidemiology of Primary Angle-closure Glaucoma

Mechanisms in Angle-closure Glaucoma

Pathogenesis of Angle-closure Glaucoma and the Role of the Lens

Current Surgical Treatment Options for Primary Angle-closure Glaucoma

Lens Extraction in Primary Angle-closure Glaucoma

Lens Extraction for Secondary Angle-closure Glaucomas

Conclusion

Method of Literature Search

J Cataract Refract Surg

Ophthalmology

Am J Ophthalmol

Ophthalmology

Ophthalmology

Surv Ophthalmol

Ophthalmology

Ophthalmology

Ophthalmology

Ophthalmology

J Cataract Refract Surg

Ophthalmology

J Cataract Refract Surg

Ophthalmology

Trans Am Acad Ophthalmol

J Cataract Refract Surg

J Cataract Refract Surg

Ophthalmology

Am J Ophthalmol

J Cataract Refract Surg

Am J Ophthalmol

Am J Ophthalmol

Surv Ophthalmol

Am J Ophthalmol

Ophthalmology

Ophthalmology

Ophthalmology

J AAPOS

Am J Ophthalmol

Ophthalmology

Ophthalmology

Am J Ophthalmol

Ophthalmology

Ophthalmology

Ophthalmology

Am J Ophthalmol

J Cataract Refract Surg

Am J Ophthalmol

Ophthalmology

Ophthalmology

Surv Ophthalmol

Ophthalmology

The Advanced Glaucoma Intervention Study, 8: Risks of cataract formation after trabeculectomy

Arch Ophthalmol

Anterior depth in Greenland Eskimos I. A population study of variation with age and sex

Acta Ophthalmol

American Academy of Ophthalmology

Preferred Practice Pattern

Nanophthalmia and chronic angle-closure glaucoma

J Glaucoma

The management of glaucoma in nanophthalmos

Trans Am Ophthalmol Soc

Argon laser iridoplasty in chronic angle closure glaucoma

Int Ophthalmol

A new operation for glaucoma involving a new principle in the etiology and treatment of chronic primary glaucoma

Arch Ophthalmol

Clinical ocular biometry (oculometry)

Bull Soc Belge Ophthalmol

Major Review
Angle-closure Glaucoma: The Role of the Lens in the Pathogenesis, Prevention, and Treatment