- Ophthalmic emergency
Clinical definitions:Based on objective findings, this classification is widely used in the classification of subjects in research
- Primary Angle Closure Suspect (PACS): Eye in which appositional contact between the peripheral iris and posterior trabecular meshwork is present or considered possible, in the absence of elevated intraocular pressure (IOP), peripheral anterior synechiae (PAS), disc or Visual Field (VF) changes.
- Primary Angle Closure (PAC): PACS with statistically raised IOP and/ or primary PAS, without disc or VF changes
- Primary Angle Closure Glaucoma (PACG): PAC with glaucomatous optic neuropathy and corresponding VF loss.
Ocular risk factors:PCAG is caused by disorders of the iris, the lens, and retrolenticular structures.
- Crowded anterior segment in a small eye
- Shallow central anterior chamber depth
- Thicker and more anteriorly positioned lens
- Short axial length of the eye
- Female sex
- Older age
- Asian ethnicity (eg, Chinese)
Primary closed-angle glaucoma is characterized by apposition of the peripheral iris against the trabecular meshwork resulting in obstruction of aqueous outflow by closure of an already narrow angle of the anterior chamber.
Typical features of PACG eye:
- Shallow anterior chamber
- Increased thickness of the lens
- Hyperopic refractive error
- Short axial length
- Sudden onset of severe unilateral eye pain or a headache
- Associated with blurred vision, rainbow-colored halos around bright lights
- Nausea and vomiting
Vogt’s triad:Seen in postcongestive glaucoma and in treated cases of acute congestive glaucoma
- Glaucomflecken: Anterior subcapsular lenticular opacity
- Patches of iris atrophy
- Slightly dilated non reacting pupil (due to sphincter atrophy)
- Hazy cornea (due to very high IOP)
- Pupil mid-dilated and vertically oval
- Pupil poorly reactive to light
- Classically, the eye is rock hard
Gonioscopy:Simple, handheld, mirrored instrument is placed on the patient’s eye, followed by examination of the angle using a slit-lamp biomicroscope
Shaffer system:Describes the degree to which the anterior chamber angle (ACA) is open
Acute primary angle-closure is an ocular emergency and requires immediate management to avoid blindness. The aims of the treatment are to achieve rapid pressure control with topical and systemic medications to limit optic nerve damage.
- IV Acetazolamide f/b oral taper (carbonic anhydrase): Reduces aqueous humour production
- IV Mannitol
- First-line antiglaucoma medications
Laser peripheral iridotomy:Eliminate pupillary block and widen the angles by reducing the pressure differential between the anterior and posterior chambers
Laser iridoplasty:By applying surface photocoagulation burns in the iris, tissue contraction results in pulling of the peripheral iris away from the trabecular meshwork, thereby opening the anterior chamber angle.
Surgical iridectomy:If iridotomy is unsuccessful or difficult to perform because of a cloudy cornea
- Prophylactic iridotomy should be carried out for the fellow eye, which is at high risk of acute angle closure.