Primary%20angle-closure%20glaucoma Diagnosis

Primary Angle-Closure versus Secondary Angle-Closure

• Primary angle-closure can occur with no identifiable cause (idiopathic), and occurs in an anatomically predisposed eye
• If the cause of angle closure (eg ocular or systemic factors) can be identified, then it is said to be secondary

Classification of PACD Spectrum

Primary Angle-Closure Suspect (PACS)

• Characterized by ≥180 degrees or ≥2 quadrants of ITC, with normal IOP, absence of peripheral anterior synechiae (PAS) and without evidence of glaucomatous optic neuropathy
• Studies showed that untreated PACS may develop elevated IOP or PAS over 5-6 years

Primary Angle-Closure (PAC)

• Defined by at least 180 degrees of ITC together with an elevated IOP or PAS or both, without optic neuropathy

Primary Angle-Closure Glaucoma (PACG)

• PACD in the presence of glaucomatous optic neuropathy
• Patients may be asymptomatic presenting for routine eye care, or may present with sudden onset of symptoms and signs of acute angle closure attacks
  
  • Symptoms may include intermittent or episodic blurring of vision, eye pain, eye redness, frontal headache, glare and halos or colored rings around lights, poor light or dark adaptation, difficulty tracking fast-moving objects, nausea, and vomiting
• PACG causes 3 times more blindness than primary open-angle glaucoma (POAG)

Acute Angle-Closure Crisis (AACC)

• Rapid increase of IOP due to sudden obstruction of the chamber angle with complete ITC
• May lead to pressure-induced corneal edema (manifested as blurred vision and at times, multicolored halos around lights), mid-dilated pupil, vascular congestion, eye pain, and/or headache
• Elevated IOP can be accompanied by nausea and vomiting
• May be self-limited and resolve spontaneously or may occur repeatedly
• May result to permanent loss of vision if left untreated and may affect the other eye

Acute Angle-Closure Glaucoma (AACG)

• Sudden and severe elevation of the IOP that does not resolve spontaneously, resulting from total closure of the iridocorneal angle
• Often brought about by sudden dilation of pupils from darkness, medications or sympathetic arousal
• Diagnostic criteria include increased IOP >21 mmHg with occludable angle with:
  • Any 2 of the following symptoms:
    • History of blurring of vision and halos
    • Nausea and/or vomiting
    • Ocular and periocular pain
  • And any 3 of the following signs:
    • Conjunctival injection
    • Corneal epithelial edema
    • Mid-dilated and reduced or unreactive pupil
    • Shallow anterior chamber

Chronic Angle-Closure Glaucoma (CACG)

• Characterized by permanent synechial closure of the chamber angle confirmed by indentation gonioscopy
• Eye discomfort, visual disturbances and transient “halos” may be experienced
• Signs:
  
  • Elevated IOP (>21 mmHg, depending on degree of ITC)
  • Peripheral anterior synechiae of varying degrees
  • ONH damage pattern consistent with glaucoma
  • Visual field (VF) defects

Intermittent Angle-Closure Glaucoma (IACG)

• Sometimes referred to as subacute angle-closure glaucoma
• Similar to AACG but with symptoms occurring in intermittent milder attacks; symptoms are spontaneously relieved after ≥1 hour
• Signs:
  
  • May resemble AACG but in a milder form
  • May vary according to degree of ITC of chamber angle
  • Atrophy of optic disc rim with afferent pupillary defect may be seen

Past Ophthalmic History

• Use of topical or systemic medications that may precipitate angle narrowing (eg sulfonamides, Topiramate, phenothiazines, anticholinergic drugs, tricyclic antidepressants, steroids)
• Trauma, previous eye treatment or laser surgery
• Allergies and adverse effects of drugs

Past Medical History

• Exclude past history of systemic conditions that may mimic glaucoma but are not progressive (eg hemodynamic crises like postpartum hemorrhage, blood transfusions, severe trauma, anterior ischemic optic neuropathy that may cause optic pallor and cupping, or intracranial diseases)
• Systemic diseases [eg asthma, chronic obstructive pulmonary disease (COPD), cardiac arrhythmias, hypotension/hypertension, diabetes mellitus (DM), thyroid eye disease, pituitary tumors, previous head injury, cerebrovascular accidents, dementia, or arthritis]
• Inquire regarding all medications taken including drug allergy
• Factors that will affect life expectancy

Family History

• Type and course of disease in the family

Socioeconomic Factors

• Consider patient’s compliance and financial capacity
• Effects of glaucoma in the patient’s life, work, and family

Refractive Status

• Hyperopic eyes, especially in older phakic patients, have narrower anterior chamber angles and are at higher risk of PACD
  • Approximate the refractive status by measuring the eyeglass power to determine the possibility of hyperopia or refracting the other eye

• Retinoscopy to assess the actual refractive status

Pupil

• Examine the size, shape, reactivity of the pupil and presence of relative afferent pupillary defect
  
  • Pupil may be asymmetric or oval in the affected eye during or after an acute attack
  • Pupil may be poorly reactive or mid-dilated during an acute attack; tonic following an attack
  • Afferent pupillary defect may be present in chronic angle closure or in an asymmetric optic nerve damage

Slit-lamp Biomicroscopy

• In acute cases, look for conjunctival hyperemia, corneal swelling with or without microcytic edema
• In recent attacks, check for anterior chamber inflammation, iris abnormalities (eg diffuse or focal atrophy, posterior synechiae, abnormal pupillary function, irregular pupil shape, and a mid-dilated pupil)
• Other manifestations:
  
  • Central and peripheral ACD narrowing
  • Lens changes such as cataract and glaukomflecken (patchy, localized, anterior subcapsular lens opacities)
  • Small corneal diameter
  • Corneal endothelial cell loss

Intraocular Pressure (IOP) Measurement

• Normal IOP is 10-21 mmHg and tends to increase with age
• Use a contact applanation method, typically Goldmann tonometry, to determine the IOP
• Perform IOP measurement prior to gonioscopy
• Measure central corneal thickness after the acute attack has resolved

Pupil Dilation

• May not be advisable in patients with ITC
  
  • However, an attempt should be made to evaluate the fundus and optic nerve head (ONH) using direct ophthalmoscope or indirect ophthalmoscopy at the slit-lamp biomicroscope with a 78- or 90-diopter lens

• Not also recommended in PACD and PACS patients who are not having an acute attack until an iridotomy has been performed
  
  • Dilation can precipitate acute attacks

• Evaluation of the ONH, retinal nerve fiber layer (RNFL), and VFs may be done after an adequate treatment of an acute attack

Anterior Segment Imaging

• Examples are anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy 
• Used only in cases which are most difficult to interpret because of its limited availability and costs
• Should be considered when assessment of angle anatomy is difficult with gonioscopy
  • AS-OCT can assess angle qualitatively and quantitatively but with some limitations
• Useful in elucidating plateau iris
  • Ultrasound biomicroscopy can determine the cause of plateau iris, plateau iris configuration and ciliary body compared to AS-OCT

Gonioscopy

• Standard technique for identifying ITC
• Evaluates the angle anatomy, appositional closure, presence of PAS and plateau iris configuration
• Should be done in a dark room with a bright, short, and thinnest beam that does not pass through the pupil to avoid inducing pupillary constriction, which can widen the angle
  • Dark-room dynamic gonioscopy can determine the cause of plateau iris
• Visualization of the angle may be impaired due to corneal edema in cases of acute angle-closure glaucoma (AACG)
  • Topical glycerin can be used to clear the cornea to have a better view

• Serial gonioscopy may also be a preferred therapy if without signs of chronic angle damage and glaucomatous optic neuropathy

Ocular Biometry

• May be considered in angle closure to measure axial length and ocular lens power prior to cataract surgery
• Useful to identify nanophthalmos (short axial length or <20 mm) prior to incisional surgery to avoid complications such as shallowing of anterior chamber and aqueous misdirection

Provocative Tests

• Provide little additional information since they cannot exclude the possibility of angle closure even if the tests are negative
• May trigger an acute angle-closure attack

• No single screening test is sufficient to determine patients with and without glaucoma

• It has been estimated that half of glaucoma cases worldwide is caused by PACD
  • Optic nerve damage occurs in approximately 75% of patients with PACG in Asia

• Opportunistic glaucoma screening
  • Relies on detection of glaucoma in patients who present for other reasons
  • Involves comprehensive ophthalmologic examination among patients >35 years old who seek ophthalmic attention for any reason
  • Should be considered in patients with risk factors especially patients with diabetes or family history of glaucoma

• Universal glaucoma screening
  • Strategy wherein health care professionals seek out patients in the general population
  • Not feasible in developing countries since there is not enough infrastructure available (eg availability of expertise, time, and instrumentation) required to confirm diagnosis among patients with positive results

• For non-ophthalmologic professionals, screening consists of a comprehensive assessment of risk factors, IOP measurement and optic disc examination
  • If slit-lamp examination is available, assess limbal ACD

• Screening in an ophthalmologist’s clinic consists of a comprehensive clinical examination which includes slit-lamp examination, IOP measurement, dilated optic disc examination and gonioscopy
  • Optic disc examination and perimetry will only detect PACD in the presence of a damaged optic disc or VF
  • Tonometry will only detect PACD if IOP is elevated

• Currently, periodic routine comprehensive eye examination is the optimal method for screening glaucoma
  • Opportunistic screening is recommended in the absence of an ideal screening method

• Diagnosis is based on history and comprehensive ophthalmological examination