PSEUDOEXFOLIATIVE GLAUCOMA

GUEST AUTHOR

SAFIA FATIMA

Ajmal Khan Tibbiya College

Aligarh, India

INTRODUCTION

Pseudoexfoliative syndrome (PES) is a systemic disorder caused by progressive accumulation of extracellular material over various ocular tissues.

Pseudoexfoliative glaucoma (PEG or PXG) has been widely described as a result of accumulation of exfoliative material, which obstructs the trabecular meshwork leading to increased intra-ocular pressure (IOP) levels.

Common sequence variants of LOXL1 gene are associated with increased risk of PES/PEG.

DIAGNOSIS AND CLINICAL FINDINGS

Within the eye, fibrillar granular pseudoexfoliative material which is characteristic of PEG seems to be mostly produced from the lens capsule, ciliary body, corneal endothelium, zonules and the iris.

Diagnosis can be done by electron microscopy and immune-chemistry studies of the material.

Slit-lamp examination, including gonioscopy and pupillary dilatation represents the gold standard procedures for the diagnosis of PEG.

Poor and impaired pupillary dilatation in PEG eyes seems to be caused by fibrillar deposits and ischemic damage to the iris causing stromal atrophy.

Ultrasound biomicroscopy (UBM) is helpful in cases where alteration of zonules and presence of iridodonesis or subluxation of the lens are suspected.

Iris Fluorescein angiography reveals the possible presence of iris ischemia.

IOP measurement: PEG is characterized by important fluctuations in diurnal IOP. Efforts should be made to measure the IOP at different times of the day in order to guide the clinician in the therapeutic management.

LENS:

Accumulation of whitish material deposits on the lens capsule can be seen on slitlamp biomicroscopy.

Typical bull’s eye appearance (central disc of material, a peripheral part containing the material and a clear area between the two) appears due to movement of the iris on to the anterior surface of the lens.

There is higher incidence of cataract on the affected side in unilateral cases.

CORNEA:

Pseudoexfoliative material and pigment on corneal endothelium (inflammatory precipitates) are seen on slit-lamp examination.

Non-specific changes of corneal endothelium include: rarefaction and thinning of the cells, cytoplasmic vacuolation, phagocytosis and melanin granules and abnormal extracellular matrix production.

AQUEOUS HUMOR AND ANTERIOR CHAMBER:

Reduced aqueous humor production.

Higher levels of protein concentration in the aqueous.

IRIS:

Presence of pseudoexfoliative material is observed on the anterior and posterior surface of the iris.

Irregular border and grayish material deposits.

Iris ischemia and neovascularization as a consequence of deposition of pseudoexfoliative material on the vascular endothelium of iris.

ZONULES AND CILIARY BODY:

There is zonular fragility caused by accumulation of pseudoexfoliative material on the ciliary processes and zonules which may lead to phacodonesis.

Defective basement membrane of ciliary body and lens.

ANGLE:

Changes in both aspect and depth of the angle commonly occur in PEG.

Pigment and flecks of pseudoexfoliative material can be observed over the structure of angles, especially along Schwalbe’s line. The pigment dispersion pattern in this area is called “Sampaolesi’s line”.

ASSOCIATION OF PES AND GLAUCOMA:

PES is considered to be one of the most common causes of secondary open angle glaucoma and early cataract development because of its characteristics including poor pupillary dilatation, posterior synechiae, subluxation or dislocation of lens and presence of weakened zonules.

PEG may be due to the congestion of the trabecular meshwork.

PEG is mostly bilateral and asymmetric. When compared to POAG, it presents a worse prognosis due to higher fluctuations of IOP.

PEG increases with age and has a higher prevalence in patients between 60-70 years.

Men are more affected than women.

MANAGEMENT OF GLAUCOMA AND CATARACT SURGERY IN PES PATIENTS

Presence of pseudoexfoliative material in the anterior segment makes surgical procedures for both cataract and glaucoma more complicated.

Eyes with PEG respond poorly to medical therapy and therefore, patients affected by PES/PEG usually undergo laser or surgical therapy.

Argon Laser Trabeculoplasty (ALT) has good response in PEG eyes.

Selective Laser Trabeculoplasty (SLT) is a repeatable procedure and a good alternative to ALT.

Trabeculectomy still represents the most frequent incisional procedure in the surgical management of PEG patients when medical/laser treatments fail to control IOP adequately.

Angle based procedures:

Surgical removal of pseudoexfoliative material in the trabecular meshwork may lead to successful lowering of IOP.

The most commonly performed angle procedures are ab interno trabeculectomy and trabecular aspiration.

Viscocanalostomy is considered as another angle based procedure, which avoids the risks associated with filtering surgery.

ExPress implant: This procedure has also been introduced to improve trabeculectomy technique and success rates in PEG patients.

Aqueous Shunt implantation: Aqueous shunts (Glaucoma Drainage Devices) have lower early and late complication rates in these patients, compared to trabeculectomy.

CATARACT SURGERY:

In evaluating patients of PES for cataract surgery, the intra-operative IOP spikes and degree of glaucoma should be taken into consideration. Also look for corneal endotheliopathy, poor mydriasis, lens subluxation and zonular instability.

Moreover, when choosing an intraocular lens, a 3-piece IOL is considered a better choice in PEG patients.

CONCLUSIONS:

Several factors must be considered when evaluating patients with PES and/or PEG in order to determine the most suitable management strategy.

Careful examination and evaluation should be performed in order to choose the most appropriate medical and surgical approach for glaucoma and cataract surgery in PES/PEG patients.