L1 Vision Pathway/Glaucoma

Question 1

Describe the Visual Pathway

Answer 1

Optic Nerve => Optic Chiasm where fibers cross=> Optic Tract from Chiasm => Lateral Geniculate Nucleus (SYNAPSE) => Optic Radiation from LGN to the Occipital Cortex

Question 2

Pressure on Optic Chiasm (Pituitary Tumour) => _____________

Answer 2

Pressure on Optic Chiasm (Pituitary Tumour) => Bi-Temporal Hemianopia

Question 3

Beyond chasm, unilateral lesion => ____________________

Answer 3

Beyond chasm, unilateral lesion => Homonymous Hemianopia on OPPOSITE Side

Question 4

Chronic Causes of Vision Loss?

Answer 4

Cataracts

Glaucoma (POAG)

Age-Related Macular Degeneration (‘dry/wet’)

Diabetic Retinopathy (maculopathy/proliferative)

Question 5

Acute Painful Causes of Vision Loss?

Answer 5

Acute angle closure glaucoma

Temporal (giant cell) arteritis

Corneal ulceration

Endophthalmitis

Acute uveitis

Question 6

Common cause of visual impairment in the elderly?

Answer 6

GLAUCOMA

Can occur in children too (congenital glaucoma => Increased corneal diameter (>11mm))`

Question 7

Clinical Features of Glaucoma?

Answer 7

• Optic Nerve Cupping/Pallor
• Peripheral Visual Field Loss (Asymmetric)
• Elevated Ocular pressure (can occur with normal pressure)
• Majority of patients have OPEN Angle Glaucoma. Minority have ACUTE Angle Glaucoma

Question 8

What can increase the risk of developing Glaucoma?

Answer 8

STEROIDS

Question 9

What is used to Diagnose Glaucoma?

Answer 9

Goldman Tonometer (Normal 5-21mmhg)

Ratio of Cup to Disk Compared

Question 10

Primary Open Angle Glaucoma (POAG) Pathogenesis?

Answer 10

Optic Nerve Damage: Incr. IOP => reduced ocular vascular perfusion pressure

Elevated IOP: reduced drainage of the aqueous humour through the trabecular meshwork drainage angle

Reduced OPP (BP entering eye) esp diastolic => Peripheral Vasospasm

Question 11

Tools to measure visual field loss in Primary Open Angle Glaucoma (POAG)?

Answer 11

Detected/monitored using Humphrey Visual Field Analysis

Question 12

Goals of Glaucoma Treatment?

Answer 12

Question 13

First Line Therapy for Glaucoma?

Answer 13

FIRST LINE: Prostaglandin Analogues

• Increase Aqueous Humor Outflow
• No Systemic effects
• Some will get darker eyelashes

Question 14

Second-Line Therapies for Glaucoma?

Answer 14

SECOND LINE: Reduce AH Secretion

Beta Adrenergic Blockers have Systemic Absorption:

• Respiratory SEs: Bronchospasm (Contraindicated in Pts. w/ ASTHMA!!)
• Cardiovascular SEs: Bradycardia, Hypotension
• Others: Depression, Lethargy, Impotence

Carbonic Anhydrase Inhibitors (CAI) SEs:

• Peripheral Paranesthesia
• General Malaise: Depression, Weight Loss
• GI Upset
• Renal/Metabolic: Hypokalemia, Acidosis
• Agranulocytosis
• Steven Johnson Syndrome
• Aplastic Anemia

Question 15

Surgical Intervention for Glaucoma?

Answer 15

Trabeculectomy: creates a new pathway for fluid inside the eye to be drained

Question 16

Glaucoma can occur in normal IOP (______________________) which is associated w/ ________ and ______________

Answer 16

Glaucoma can occur in normal IOP (NORMAL TENSION GLAUCOMA) which is associated w/ Migraine and Raynaud’s Phenomenon