Glaucomas II: Presentation and Management

• Mostly asymptomatic in the early stages
• Exceptions: congenital glaucoma, acute angle closure, secondary glaucomas
• Family history
• History of risk factors – myopia, hypertension, diabetes, abuse of steroid eye drops

ONH Assessment

Cup to disc ratio 0.6 and above raises suspicion of glaucoma. Several other characteristics of the ONH are evaluated by ophthalmologists.

×

×

Ophthalmoscopic Signs of Glaucoma:

• Generalized:
  • Large optic cup
  • Asymmetry of the cups
  • Progressive enlargement of the cup
  • Nerve fiber layer hemorrhage
• Focal:
  • Notching of the rim
  • Vertical elongation of the cup
  • Cupping to the rim margin
  • Nerve fiber layer loss
• Less Specific:
  • Exposed lamina cribrosa
  • Nasal displacement of vessels
  • Baring of circumlinear vessels
  • Peripapillary atrophy

Clinical ONH Assessment

• Slit lamp biomicroscope
• Direct ophthalmoscope

Slit lamp biomicroscope

×

Slit lamp biomicroscope

Direct ophthalmoscope

×

Direct ophthalmoscope

Normal Fundus

×

Normal Fundus

IOP Measurement

• Normal IOP is 10-21mmHg, average 16mmHg
• Some patients develop glaucomatous damage with IOP less than 21 mm Hg
• Reduction of IOP is a key modifiable factor in essentially all types of glaucoma
• IOP follows circadian rhythm

IOP Measurement

×

IOP Measurement

IOP Measurement

×

IOP Measurement

Visual Field Assessment (Perimetry)

• Standard method of measuring the visual dysfunction seen with glaucoma
• Also used to detect glaucoma progression

Perimetry

×

Perimetry

Early and Late VFs in Glaucoma

×

Early and Late VFs in Glaucoma

Gonioscopy

Examination technique used to visualize the structures of the anterior chamber angle

Gonioscopic appearance of a normal anterior chamber angle:

1. Peripheral iris:
   • insertion;
   • curvature;
   • angular approach.
2. Ciliary body band.
3. Scleral spur.
4. Trabecular meshwork:
   • posterior;
   • mid;
   • anterior.
5. Schwalbe line

Gonioscopy

×

Gonioscopy

Anterior Chamber Angle

×

Anterior Chamber Angle

The anterior chamber contains the ciliary body 1, the site of aqueous humor production. The aqueous humor percolates around the lens 4 and the iris 3 to drain (white lines 2) from the posterior chamber into the anterior chamber through the pupil 5. The anterior chamber angle is located between the peripheral cornea 6 and the peripheral iris, and it contains the trabecular meshwork (TM 7 red arrow) and Schlemm’s canal 8. The aqueous humor leaves the eye through the trabecular meshwork and Schlemm’s canal, and through the uveo-scleral outflow pathway in the ciliary muscle 9. Modified from Jonas et al, 2017.

Normal Open Angles

×

Normal Open Angles

Imaging Techniques

• Fundus Photography

A method for recording the appearance of the optic nerve head for detailed examination and sequential follow-up

• Optical Coherence Tomography

Structural Assessment to provide measurements of the ONH and peripapillary RNFL thickness

Preperimetric stage - RNFL loss first sign, followed by or accompanied by ONH changes.

Perimetric stage - VF changes start to show up.

Optical Coherence Tomography 

×

Optical Coherence Tomography 

• Beta blockers / antagonists
• Prostaglandin analogs – latanoprost
• Carbonic anhydrase inhibitors – dorzolamide, acetazolamide (oral, not for long term use)
• Adrenergic agonists – brimonidine
• Parasympathomimetics (miotics) - pilocarpine
• Hyperosmotic agents - mannitol

Beta Blockers / Antagonists

Examples:

• Timolol (non-selective beta-1 and beta-2 blocker)
• Betaxolol (selective beta-1-blocker)

Prostaglandin Analogs

Examples:

1. Latanoprost 0.005% (Xalatan)
2. Travoprost 0.004% (Travatan)
3. Bimatoprost 0.01% (Lumigan)
4. Tafluprost (Zioptan, preservative-free)

Dosed nightly.

Carbonic Anhydrase Inhibitors

Oral:

• Acetazolamide (Diamox)
• Methazolamide (Neptazane)

Topical Carbonic Anhydrase Inhibitors:

• Dorzolamide 2% (Trusopt)
• Brinzolamide 1% (Azopt)

Dosage: Twice a day (BID) or three times a day (TID).

Alpha-2 Selective Adrenergic Agonists

Dosed BID to TID.

• Apraclonidine 0.5% (Iopidine)
• Brimonidine (Alphagan, Alphagan P, 0.1%, 0.15%, 0.2%)

• Trabeculectomy
• Goniotomy
• Trabeculotomy
• Micro Invasive Glaucoma Surgery (MIGS)
• Aqueous Shunt Implantation

General Principles of Glaucoma Treatment

Laser Treatments

• Selective Laser Trabeculoplasty
• Argon Laser Trabeculoplasty
• Laser Iridotomy
• Laser Cyclophotocoagulation

Congenital Glaucoma

History – photophobia, tearing, enlarging eyes (buphthalmos)

Examination under anesthesia

• IOP check
• Corneal Diameters
• Refraction
• Gonioscopy
• Fundoscopy

Treatment – primarily surgical

• Goniotomy
• Trabeculotomy
• Trabeculectomy
• Aqueous shunts

Open Angle Glaucomas

Primary Open Angle Glaucoma

• Commonest in this environment; Silent until disease is advanced
• Raised IOPs, cupped discs, CVF or OCT features
• Treatment: 1st line usually medical. Surgical and laser if medical treatment fails, or if compliance is poor

Juvenile Glaucoma

• Similar to POAG; Younger age of onset
• Treatment primarily surgical

Normal Tension Glaucoma

• Similar to POAG, ‘normal’ IOPs

Angle Closure

Acute Angle Closure

• Sudden occlusion of trabecular meshwork
• Abrupt elevation in IOP – pain, nausea, haloes
• Red teary eye, hazy cornea, fixed dilated pupil
• Treatment: Emergency care. IV acetazolamide, oral acetazolamide, topical steroids, analgesics, pilocarpine.
• Laser iridotomy when stable

Chronic Angle Closure Glaucoma

• Insidious onset, asymptomatic in early stages
• Commoner in older people, Asians and Inuits, farsighted people
• Treatment – laser or surgical treatment. Eye drops may be needed