primary open angle glaucoma

Question 1

what are glaucomas

Answer 1

optic neuropathies associated with raised intraocular pressure

Question 2

how are glaucomas classified

Answer 2

classified based on whether the peripheral iris is covering the trabecular meshwork
important for drainage of the aqueous humour from the anterior chamber of the eye

Question 3

what is open angle glaucoma

Answer 3

iris is clear of the meshwork

trabecular network functionally offers increased resistance to aqueous outflow = increase in intraocular pressure

Question 4

what are fundoscopy signs of POAG

Answer 4

1. Optic disc cupping - cup-to-disc ratio >0.7 (normal = 0.4-0.7), occurs as loss of disc substance makes optic cup widen and deepen
2. Optic disc pallor - indicating optic atrophy
3. Bayonetting of vessels - vessels have breaks as they disappear into the deep cup and re-appear at the base
4. Additional features - Cup notching (usually inferior where vessels enter disc), Disc haemorrhages

Question 5

what are the features of POAG during routine optometry appointments

Answer 5

1. peripheral visual field loss - nasal scotomas progressing to ‘tunnel vision’
2. decreased visual acuity
3. optic disc cupping

Question 6

what are the symptoms of primary open angle glaucoma

Answer 6

1. slow rise in intraocular pressure = no sx for a long period
2. typically present following an ocular pressure measurement during a routine examination by an optometrist

Question 7

what are the risk factors of open angle glaucoma

Answer 7

1. increasing age
2. genetics = first-degree relative
3. afro Caribbean ethnicity
4. myopia - nearsightedness
5. hypertension
6. dm
7. corticosteroids

Question 8

what are the signs associated with primary open-angle glaucoma

Answer 8

increased ocular pressure
visual field defect
pathological cupping of the optic disc

Question 9

what are the case findings in primary open angle glaucoma

Answer 9

optic nerve head damage visible under the slit lamp
visual field defect
IOP > 24 mmHg as measured by Goldmann-type applanation tonometry
if suspected full investigations are performed

Question 10

what investigations are required in suspected open angle glaucoma

Answer 10

automated perimetry to assess visual field
slit lamp examination with pupil dilatation to assess optic neve and fundus for a baseline
applanation tonometry to measure IOP
central corneal thickness measurement
gonioscopy to assess peripheral anterior chamber configuration and depth
Assess risk of future visual impairment, using risk factors such as IOP, central corneal thickness (CCT), family history, life expectancy

Question 11

describe the management of primary open -angle glaucoma

Answer 11

eye-drops = lower intraocular pressure - shown to prevent progressive loss of visual field.

1st line = prostaglandin analogue eyedrop (PGA)
second line = beta blocker, carbonic anhydrase inhibitor or sympathomimetic eyedrops
third eye = surgery or laser can be tried

Question 12

why is reassessment important in pt with open-angle glaucoma

Answer 12

exclude progression and visual field loss

Question 13

reassessment needs to be done more frequently in pt with primary open anggle glaucoma if…

Answer 13

IOP uncontrolled
the patient is high risk
or there is progression

Question 14

give an example of a PGA and its mode of action + SE

Answer 14

latanoprost

acts to increase uvesleral outflow

SE = Adverse effects include brown pigmentation of the iris, increased eyelash length

Question 15

give an example of beta blockers for primary open-angle glaucoma and its mode of action + SE

Answer 15

timolol and betaxolol

reduces aqueous production

avoid in patients who have asthma and heart block

Question 16

give an example of symapthomimetics for primary open-angle glaucoma and its mode of action + drug notes

Answer 16

brimoindine - a2 receptor agonist
reduces aqueous production and increases outflow

Avoid if taking MAOI or tricyclic antidepressants

Adverse effects include hyperaemia

Question 17

describe example, MOA and Drug notes for carbonic anyhrase inhibitors used in primary open angle glaucoma

Answer 17

dorzolamide

reduced aqueous production

Systemic absorption may cause sulphonamide-like reactions

Question 18

give an example of miotics used in open-angle glaucoma, action and adverse effects

Answer 18

pilocarpine = muscuranic receptor agonist

increases uveoscleral outflow

adverse effects = constricted pupil and blurred vision