Glaucoma

Question 1

What is glaucoma?

Answer 1

Group of ocular disorders that result in optic nerve damage, often associated with increased intraocular pressure (IOP). *Glaucoma is the 2nd leading cause of blindness behind cataracts

Question 2

Classification of glaucoma

Answer 2

Open angle Closed angle Normotension

Question 3

Describe the flow of aqueous humour normally

Answer 3

The pressure balance of the eye is maintained by the flow of aqueous humour. The ciliary body produces the aqueous humour into the posterior chamber. The fluid then moves towards and around the iris, through the pupil and into the anterior chamber. The fluid drains via the trabecular meshwork (via Schlemm’s canal and into a vein) or by the uveoscleral outflow routes.

Question 4

Picture/ draw out the simple anatomy of the flow pathway of aqueous humour

Answer 4

Question 5

What is the anterior chamber angle?

Answer 5

The angle formed between the iris and the cornea

Question 6

Define angle closure glaucoma

Answer 6

Glaucomatous Sx developing in a patient with increased IOP and narrow/closed anterior chamber angle *Often due to smaller eyes -> smaller chambers i.e. Asians

Question 7

Classifications of angle closure glaucoma

Answer 7

Acute Chronic

Question 8

Define open angle glaucoma

Answer 8

Glaucomatous Sx developing in pt with increased IOP and a properly opened angle *Often due to abnormal structural trabecular network

Question 9

Define normotension glaucoma

Answer 9

Glaucomatous Sx developing in pt with normal IOP and properly open angle * Ass with vasospasm

Question 10

What is occular HTN?

Answer 10

Increase IOP in patients without Sx of glaucoma or optic disk abnormalities NB: some people have increase IOP but no glaucoma, some people have normal IOP but glaucoma (normotension glaucoma)

Question 11

What is tonometry?

Answer 11

Measurement of IOP

Question 12

What is normal IOP?

Answer 12

12-20mmHg

Question 13

What is pachmetry?

Answer 13

Measurement of the thickness of the cornea

Question 14

What is gonioscopy?

Answer 14

Measurement of the anterior chamber angle

Question 15

What are the risk factors of glaucoma?

Answer 15

• increased age - blacks and asians - FHx - Myopes and hyperopes - Corticosteroids - Thin cornea

Question 16

What is acute angle closure glaucoma (AACG)?

Answer 16

Glaucomatous exacerbation due to an insufficient anterior angle leading to increase IOP

Question 17

Causes of AACG

Answer 17

Intrinsic: narrow anterior angle anatomically (Asians) Extrinsic: anything that dilates the pupil leading to a AACG attack e.g. dark room, stress, antiACh, SSRIs, sympathomimetics

Question 18

Pathophysiology of extrinsic cause of AACG

Answer 18

When the pupil dilates the iris relaxes and becomes convex, this leads to a decrease in the anterior chamber angle INSERT PIC

Question 19

Sx of AACG

Answer 19

Severe ocular pain Red eye, N/V, dilated pupil

Question 20

Dx of AACG

Answer 20

Tonometry - IOP > 50 mmHg with clinical Sx

Question 21

Rx of AACG

Answer 21

1st line: IV acetazolamide: carbonic anhydrase inhibitor which reduces aq humour production Other: osmotic diuretic Then referral to opthalmologist Then tonometry, if IOP decreased then administer pilocarpine (parasympathomimetic - constrict pupils)

Question 22

Causes of chronic angle closure glaucoma (CACG)

Answer 22

a. Periperhal anterior syncechiae (iris adhesions to the lens) b. Narrowed anterior angle (Asians, elderly, cataracts or lens thickening)

Question 23

Sx of CACG

Answer 23

Pts are typically asymptomatic until alter in the course - mild blurring, visual field deficits, halos, redness and iris blotches (nothing like AACG)

Question 24

Dx of CACG

Answer 24

Gonioscopy will differentiate CACG glaucoma from open angle glaucoma which presents and progresses similarly

Question 25

Rx of CACG

Answer 25

Referral to ophthalmology for iridotomy (first line Rx) - burn hole in iris Anti-glaucoma medications needed after surgery

Question 26

What is Primary Open Angle Glaucoma (POAG)?

Answer 26

anatomically open angle but with an obstructed and slowed drainage system outflow

Question 27

____ is the most common form of glaucoma in Australia?

Answer 27

POAG

Question 28

3 major clinical features of POAG

Answer 28

1. Progressive visual field loss (peripheries to total blindness) 2. Progressive increase in cup to disc ratio of optic disc 3. Elevated IOP (NB: sometimes may be normal at initial Dx) with normal open anterior angle * pt may present without Sx or may be detected on routine eye exam due to optic disk abnormalities (inc cup:disc). Even if silent, pt will inevitably go on to develop Sx

Question 29

In POAG what will the cup-to-disc ratio be?

Answer 29

> 0.5

Question 30

What is the normal cup:disc ratio?

Answer 30

0.3

Question 31

What is the cup of the optic disc?

Answer 31

White, cup like depression/area at the centre of the optic disc

Question 32

Sx of POAG

Answer 32

Typically late course of disease: Visual field deficits - paracentral Rainbow halos Mild eye pain Redness

Question 33

Dx of POAG

Answer 33

Referral to opthalmology with: Fundoscopy to look for optic disc changes Gonionscopy to rule out CACG Tonometery Slit lamp examination Visual field analysis

Question 34

Describe the progressive change in visual field loss in POAG

Answer 34

Question 35

Rx of POAG

Answer 35

Goal: decrease IOP by > 25% Medical: eye drops of: a. prostaglandin analogs*: latanoprost b. beta blockers*: timolol c. Alpha-2 agonist : brimonidine d. Miotics: pilocarpine (PNSmimetic) e. Carbonic anhydrase inhibitor Surgery: Argon laser trabeculoplasty (create drainage path for aq humour)

Question 36

What is normal tension glaucoma?

Answer 36

Considered a type of POAG. Pt must have optic disc changes and may progress to Sx of glaucoma but IOP ALWAYS normal * associated with vasospasm (Hx of migraine, Raynaud’s syndrome)