Glaucoma. IntroIntro. Aqueous Production & Flow. Pathophysiology. Assessment. Types. Medical...

Glaucoma

Intro. Aqueous Production & Flow. Pathophysiology. Assessment. Types. Medical Treatment. Surgical Treatment

Glaucoma

An optic neuropathy characterized by:

–Elevated intraocular pressure–Optic disk cupping –Visual field loss


Normal visual field


Shrinking vision


Advanced field loss


Tunnel vision


Raised intraocular pressure

Impaired outflow of aqueous resulting from:

abnormalities within the drainage system of the anterior chamber angle (i.e. open-angle glaucoma) Impaired access of aqueous to the drainage system

(i.e. closed angle glaucoma)


Physiology of the Aqueous Humor

Clear liquid that fills anterior and posterior chambers of the eyeUltrafiltrate of plasma produced in the stroma of the ciliary processVolume: 250 uL, 2.5 uL/minOsmotic pressure: slightly higher than plasmaComposition : like plasma but higher concentration of ascorbate, pyruvate and lactate & lower concentration of protein, urea, and glucose


Aqueous formation and flow• Ciliary body

• Posterior chamber

• Pupil

• Anterior chamber

• Trabecular meshwork

• Schlemm’s canal


Pathophysiology

• Ganglion cell atrophy - Major mechanism of visual loss in glaucoma - Leads to thinning of the inner nuclear and nerve layers of the retina and axonal loss in

the optic nerve

• Optic disk becomes atrophic, with enlargement of the optic cup• Iris and ciliary body also become atrophic and the ciliary processes show hyaline degeneration


Risk Factors for developing Glaucoma

• Age (>40 years old)• Females > Males• Hyperope• (+) Family history of glaucoma• GIC1a (myocillin gene) in open angle gl• Systemic disease: HPN, DM• Trauma• Underlying ocular conditions: ex. CRAO,

phacolytic, uveitis• Drugs, ex. steroids


Clinical Assessment

1. Fundoscopy / Optic Disc Assessment

2. Tonometry3. Gonioscopy4. Visual Field Evaluation

Optic Disk Assessment

• Physiologic Cup– Normal central

depression– Size depends on the

bulk of the fibers that form the optic nerve relative to the size of the scleral opening

– Hyperopic eyes – scleral opening is small -> small optic cup


Optic Disk Assessment

• Glaucomatous optic atrophy– Loss of disc substance; enlargement of optic

disc cup– Disc pallor in the area of cupping– Concentric enlargement of the optic cup or

preferential superior and inferior cupping with focal notching of the rim of the optic disc

– Retinal vessels on disc are displaced nasally– “bean pot cup” – Cup-disc ratio: ratio of cup size to disc

diameter (>0.5 or significant asymmetry between the two eyes)

– Atrophy of nerve fiber layer (Hoyt’s sign)


Optic Disc Cupping:


Tonometry

• Measurement of intraocular pressure (IOP) • Normal pressure = 10-24 mmHg

• Types of Tonometry– Goldmann Applanation Tonometer – measures

the force required to flatten a fixed area of the cornea, gold standard

– Perkins Tono Pen – portable– Pneumomatotonometer – irregular surface

cornea– Schiotz – portable, measure corneal

indentation produced by known weight


Applanation Tonometry


Gonioscopy

• Clinical technique used to examine structures in the anterior chamber

• 4 structures:– Schwalbe’s line– Trabecular

meshwork– Schlemm’s canal– Ciliary body


Visual Field Exam:

Confrontation Test - Simplest - Used for screening purposes only

Goldmann Perimeter - Kinetic form of visual field testing

THANK YOU!

Glaucoma. IntroIntro. Aqueous Production & Flow. Pathophysiology. Assessment. Types. Medical...

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