Glaucoma

Glaucoma – A Comprehensive Overview

Glaucoma is a group of eye disorders that cause progressive damage to the optic nerve, often associated with increased intraocular pressure (IOP). It is one of the leading causes of irreversible blindness worldwide. Glaucoma is typically asymptomatic in early stages, which is why it’s often called the "silent thief of sight."

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🔍 Types of Glaucoma

1. Primary Open-Angle Glaucoma (POAG)

• Most common type

• Caused by slow clogging of the drainage canals.

• Angle between iris and cornea remains open.

• Painless and asymptomatic until significant vision loss occurs.

• Gradual peripheral vision loss, leading to tunnel vision.

2. Angle-Closure Glaucoma (ACG) / Closed-Angle Glaucoma

• Acute or chronic.

• Caused by a blocked drainage angle, leading to a sudden rise in IOP.

• Symptoms (acute):

  • Severe eye pain

  • Headache

  • Nausea and vomiting

  • Blurred vision with halos

  • Red eye

3. Normal-Tension Glaucoma

• Optic nerve damage occurs despite normal IOP.

• Possibly related to poor blood flow to the optic nerve.

4. Secondary Glaucoma

• Caused by another eye condition (e.g., uveitis, trauma, steroid use, neovascularization).

5. Congenital Glaucoma

• Rare, seen in infants or young children.

• Symptoms: enlarged eyes, excessive tearing, photophobia, cloudy cornea.

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🧠 Pathophysiology

• Aqueous humor is produced by the ciliary body, flows from the posterior chamber → pupil → anterior chamber → drains through trabecular meshwork into Schlemm’s canal.

• In glaucoma, drainage is impaired, leading to buildup of aqueous humor and increased IOP.

• High IOP damages the optic nerve head, particularly the retinal ganglion cell axons, resulting in progressive vision loss.

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👁️‍🗨️ Clinical Features

Open-Angle Glaucoma	Angle-Closure Glaucoma
Painless	Painful
Gradual loss of vision	Sudden loss of vision
Peripheral vision loss	Blurred vision with halos
No redness	Red eye
No nausea	Nausea and vomiting

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🧪 Diagnosis

1. Tonometry – Measures IOP (Normal: 10–21 mmHg)

2. Gonioscopy – Visualizes anterior chamber angle

3. Ophthalmoscopy – Examines optic nerve head (look for cupping)

4. Perimetry (Visual Field Test) – Detects peripheral vision loss

5. OCT (Optical Coherence Tomography) – Measures retinal nerve fiber layer thickness

6. Pachymetry – Measures corneal thickness (helps interpret IOP readings)

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💊 Treatment

🎯 Goals: Lower Intraocular Pressure (IOP)

1. Medications (Eye Drops)

Class	Examples	Mechanism
Prostaglandin analogs	Latanoprost, Bimatoprost	Increase outflow of aqueous humor
Beta blockers	Timolol	Decrease aqueous production
Alpha agonists	Brimonidine	Decrease production and increase outflow
Carbonic anhydrase inhibitors	Dorzolamide, Acetazolamide	Reduce aqueous production
Miotics	Pilocarpine	Increase trabecular outflow

2. Laser Therapy

• Laser Trabeculoplasty – Improves drainage in open-angle glaucoma

• Laser Iridotomy – Creates hole in iris to relieve angle-closure

• Cyclophotocoagulation – Reduces aqueous production

3. Surgery

• Trabeculectomy – Creates new drainage channel

• Tube shunt implantation – Diverts aqueous humor out of the eye

• Minimally Invasive Glaucoma Surgeries (MIGS) – For mild/moderate cases

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⚠️ Complications

• Irreversible vision loss

• Blindness if untreated

• Depression/anxiety due to vision impairment

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👶 Congenital Glaucoma – Special Notes

• Appears within 1st year of life

• Symptoms: Photophobia, tearing, corneal haze

• Requires early surgical intervention (e.g., goniotomy, trabeculotomy)

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✅ Prognosis and Follow-up

• Early detection and lifelong treatment are key to preserving vision.

• Regular eye exams, IOP monitoring, and visual field testing are essential.

• Adherence to medications is critical to prevent progression.

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📌 Summary Table

Aspect	Open-Angle	Angle-Closure
Onset	Gradual	Sudden
Pain	None	Severe
IOP	Moderately ↑	Markedly ↑
Vision Loss	Peripheral	Central
Emergency	No	Yes