Types of Glaucoma Classification

Classification of Glaucoma

• Angle-closure with pupil block
• Angle-closure without pupil block
• Open angle
• Posner-Schlossman syndrome

Lens-related Glaucoma

• Phacolytic glaucoma: open-angle glaucoma occurring in association with hypermature cataract
• Phacomorphic glaucoma: acute secondary angle-closure glaucoma precipitated by an intumescent cataractous lens
• Phacoanaphylaxis glaucoma: rare, occurs after penetrating trauma/surgery, sensitization to own lens proteins resulting in granulomatous uveitis

Pupillary Block Glaucoma

• Aqueous fluid flows forward through the pupil to the angle of the anterior chamber
• The lens seals against the iris and blocks the flow of aqueous humor through the pupil
• Form of an angle closure glaucoma

Primary Congenital Glaucoma

• Impaired aqueous outflow is caused by maldevelopment of the angle of anterior chamber
• 65% are boys, OU affected, and 75% of cases are asymmetrical
• Two classifications: True Congenital (40%) and Infantile glaucoma (55%), and Juvenile glaucoma (least common)

Changes with Primary Congenital Glaucoma

• Corneal Haze: often the first sign noticed by parents
• Buphthalmos: large eyes result of stretching due to the elevated IOP prior to age 3 yrs
• Breaks in Descemet’s membrane: secondary to IOP stretching may be associated with a sudden influx of aqueous into the corneal stroma
• Optic disc cupping: in infants may regress once the IOP is normalized

Overview of Glaucoma

• Potentially progressive and characteristic optic neuropathy associated with visual field loss
• Intraocular pressure is usually a key modifying factor
• Affects up to 2% of those over the age of 40 years globally, and up to 10% over the age of 80; 50% may be undiagnosed

Classification of Glaucoma

• Congenital (developmental) or acquired
• Open-angle and angle-closure types based on the mechanism by which aqueous outflow is impaired
• Primary and secondary glaucoma

Diagnostic Tests for Glaucoma

• IOP (intraocular pressure)
• Gonioscopy
• Optic nerve head appearance
• Visual field appearance
• Optic nerve head imaging

Methods of Checking IOP

• Goldmann tonometry
• Tonopen
• Schiotz tonometry
• Puff tonometry
• Rebound tonometry

Visual Field Tests

• Static perimetry – Humfrey VF (commonly used)
• Kinetic perimetry – Goldmann

Optic Nerve Head Imaging

• Stereo photographs
• Optical coherence tomography
• Heidenberg retinal tomograph

Optic Nerve Head Appearance

• Normal optic nerve head:
  • Neuroretinal rim
  • Rim-disc ratio
  • Cup
  • Cup disc ratio

Structures Affected/Changes in Glaucoma

• Optic nerve head:
  • A. Neuroretinal rim: follows the ISNT rule
  • B. Rim-disc ratio: indicates the thickness of the rim in four quadrants expressed as a fraction of the diameter of the disc
  • C. Cup: may have one of three main appearances
  • D. Cup-disc ratio: indicates the diameter of the cup expressed as a fraction of the diameter of the disc
  • E. Blood Vessels: BV from within the optic nerve enter the disc centrally and then course nasally from the edge of the cup

Ocular Hypertension

• Population over 40 yrs have IOP’s greater than 21mmhg without detectable glaucomatous damage on standard clinical tests
• These individuals are referred to as ocular hypertensives or glaucoma suspects

Signs of POAG

• IOP greater than 21mmhg
• Wide open angle
• Thinning of NFL
• Changes on cupping (ONH)

Risk of POAG

• Age: after age 65 y/o
• Race: more severe in blacks than whites
• Family history
• Diabetes mellitus
• Myopia
• Retinal disease: CRVO, RD, and RP

Changes of POAG in the VF

• Paracentrally scotoma: supero nasal
• Nasal: below horizontal midline in the nasal field
• Arcuate shaped: coalescence of paracentral scotomas
• Temporal wedge: due to damage to adjacent fibres

Management for POAG

• No information provided