Primary Glaucomas
Primary Glaucoma refer to a group of eye conditions that develop without any identifiable underlying cause or associated systemic disease. These conditions directly affect the optic nerve, leading to progressive vision loss if not managed effectively.
Unlike secondary glaucomas, which result from known factors like trauma or other ocular diseases, primary glaucomas arise spontaneously and can be broadly classified into two main types: Primary Open-Angle Glaucoma (POAG) and Primary Angle-Closure Glaucoma (PACG).
a. Primary Open-Angle Glaucoma (POAG)
Primary Open-Angle Glaucoma (POAG) is the most common form of primary glaucomas, accounting for the majority of cases worldwide. This condition progresses slowly and is often referred to as the “silent thief of sight” due to its asymptomatic nature in the early stages.
Gradual Optic Nerve Damage and Vision Loss:
In POAG, the optic nerve is gradually damaged over time. The nerve fibers responsible for transmitting visual information to the brain are compromised, leading to a progressive narrowing of the visual field. If left untreated, this can result in complete blindness
- Often Associated with High Intraocular Pressure (IOP):
Elevated IOP is a significant risk factor for POAG. The eye’s drainage system, primarily the trabecular meshwork, becomes inefficient, leading to increased pressure within the eye. This heightened pressure damages the optic nerve, causing irreversible vision loss.
- Normal-Tension Glaucoma:
Interestingly, POAG can also occur in individuals with normal IOP, a condition known as Normal-Tension Glaucoma. Here, factors such as poor blood flow to the optic nerve or increased sensitivity of the optic nerve to normal IOP levels play a role. Despite the absence of elevated IOP, the optic nerve suffers damage, highlighting the multifactorial nature of this form of primary glaucomas.
b. Primary Angle-Closure Glaucoma (PACG)
Primary Angle-Closure Glaucoma (PACG) is another major type of primary glaucomas. Unlike POAG, this condition is characterized by an obstruction in the drainage system caused by the narrowing or complete closure of the anterior chamber angle
- Caused by Narrowing or Closure of the Anterior Chamber Angle:
The anterior chamber angle is where the cornea and iris meet, allowing the aqueous humor to flow out of the eye through the trabecular meshwork. In PACG, this angle becomes too narrow or closes entirely, preventing fluid drainage and causing a sudden rise in IOP.
- Sudden Rise in IOP:
PACG can lead to an acute angle-closure crisis, where IOP spikes rapidly, causing severe pain, redness, blurred vision, and nausea. This is a medical emergency that requires immediate intervention to prevent permanent vision loss.
Subtypes of Primary Angle-Closure Glaucoma
Acute Angle-Closure Glaucoma:
This subtype is characterized by a rapid and dramatic increase in IOP due to the sudden closure of the anterior chamber angle. Symptoms include intense eye pain, headaches, halos around lights, and a noticeable decline in vision. Immediate treatment is essential to preserve eyesight
Chronic Angle-Closure Glaucoma:
Unlike the acute form, chronic angle-closure glaucoma progresses slowly over time. The anterior chamber angle narrows gradually, leading to subtle symptoms that may go unnoticed until significant vision loss occurs. Routine eye exams are crucial for early detection and management of this type of primary glaucomas