Primary angle-closure glaucoma Topic 53
As the name suggests , it has no obvious system or ocular cause but the rise of IOP occurs due to blockage of the aqueous humour outflow due to a narrow angle of the anterior chamber
There are factors that predispose to this (mainly anatomical )
- 1. Anatomical
Hypermetropic eyes with shallow anterior chamber eyes where iris-lens diaphragm is placed anteriorly narrow angle of chamber, due to small eyeball, large lens, small diameter of the cornea &bigger size of the ciliary body ( the structures that surround the anterior chamber)
b) General factors
Age (50-), sex (females),personality (nervous), season (rainy ), family (maybe inherited)
Race (Caucasians)
An eyes that has any of the above mentioned predisposing factors may experience an attack quickly during the following activities:
-Dim light – emotional stress -use of mydriatic drugs (like atropine) ( as the contraction of the dilators in iris move iris closer to the lens thus blocking the pathway)
Mechanism of action
=as it is primary we don’t know what causes it but we know that once you have anatomical problems, the following sequence leads to the rise in IOP thus glaucoma
The above mentioned activities cause dilation which brings lens closer To the lens (A), thus creating relative pupil block
The aqueous then collects& pushes the posterior flaccid iris (iris bombe)
As seen in B, causing iridocorneal contact→ narrowing of angle
The fluid builds up and carries on pushing the peripheral iris
Until the contact develops into Synechial angle closure as the peripheral
Iris attaches to the cornea firmly and IOP rise may last long .
PAAGs are classified in 6 different subtypes; progression to another is possible; not must
- Primary angle-closure glaucoma suspect or Latent PAAG
- Subacute primary angle-closure glaucoma or intermittent PAAG
- Acute primary angle-closure glaucoma
- Post congestive angle close glaucoma
- Chronic primary angle close glaucoma
- Absolute glaucoma
Primary angle-closure glaucoma
= known as glaucoma suspect as they are people that are predisposed due to anatomical changes thus asymptomatic ; nothing major has happened yet
Clinical sign and diagnosis
1.Eclipse sign –shadowing due to decrease axial anterior chamber By placing a light temporally against the anterior chamber
2. Gonioscopic signs- very narrow angle
3.Slit-lamp biomicroscopy
- allows examination of the anterior segment
- & posterior segment includes the eyelid, sclera,
- conjunctiva, iris, lens,& cornea
- Decreased anterior chamber depth, convex shaped iris diaph.,iris & cornea= close