Glaucoma Flashcards
Glaucoma
Characteristic changes in the optic nn head –> loss of visual field
Where is aq humour produced?
Ciliary body
How does aq drain?
Via trabecular meshwork
Where does the aq go after the trabecular meshwork?
Schlemm’s canal –> collecting channels –> venous system
What is normal intraocular pressure?
10-22mmHg
How much can IOP vary throughout the day?
by 5mmHg
When is IOP the highest?
At night
In the morning
What 2 things are IOP determined by?
Rate aq production
Resistance aq drainage
Which structural changes would suggest glaucoma (4)
Incr cup size
Asymmetrical cupping
Notching rim, vertical elongation
Vessels nasally displaced, bayonetted
What is the ISNT rule?
In normal disc:
Size inferior > superior > nasal > temporal
How do you test IOP?
Goldmann tonometer
What is a normal cup: disc
0.3
What is the normal colour of the optic disc?
Salmon pink
What are the 2 types of glaucoma?
Primary open angle glaucoma
Acute angle closure glaucoma
What Sx do you get with POAG?
Visual field defects (peripheral initially)
What % >40s have POAG
1%
What % >75s have POAG?
5%
Risk Factors POAG (6)
Raised IOP FHx Myopia Afro-Carribean DM Steriods
What cup:disc would be definitely pathological?
0.7
What happens to the optic disc colour as POAG progresses?
Disc becomes pale
What is a physiological scotoma? Where is it
Blind spot
@ optic disc, 15’ temporally
How is the open angle measured?
gonioscopy
E.g.s of drugs used to Tx POAG
PG analogues - TO latanoprost B-blockers - timolol drops A-adrenergic - Apraclonidine drops CAH inhibitors - dorzolamide, acetazolamide Miotics - pilocarpine TO
Surgical options for POAG (2)
Argon laser trabeculoplasty
Surgical trabeculectomy
Action latanoprost
Increases uveoscleral aq outflow
SE latanoprost
Red eye
Iris colour change
Eyelash growth
Periocular skin pigmentation
Action timolol
Decr aq production
SE timolol
Dry eyes Corneal anaesthesia Bradycardia Bronchospasm Depression
Action Apraclonidine
Decr aq production
Incr uvescleral outflow
SE apraclonidine
Mydriasis Lethargy Dry mouth HTN risk hypertensive crisis if on MAOIs
Action dorzolamide
Decr aq production
SE dorzolamide
Pain
Local allergic reaction
When should use of acetazlamide be used ith caution>
pregnancy
renal stones Hx
SE acetazalimide?
Met acidosis
Hypokalaemia
Paraesthesia
GI disturbance
Action pilocarpine
Contricts pupil, unblocks trabecular meshwork
C/I pilocarpine
Ant uveitis
High myopia
Retinal detachment
Aphakia
SE pilocarpine
Decr acuity
Brow ache for ciliary mm spasm
Pathophysiology of acute angle closure glaucoma
Lens becomes pushed against iris –> pupillary block
Build up of aq in posterior chamber + bulging of iris + closure of iridocorneal angle
Blocks trabecular meshwork
Risk factors AACG (4)
F (4:!)
Asians
Shallow anterior chamber
Shorter axial length
2’ causes of AACG
Uveitis
NV - DM, retinal vv occlusion
Pigment dispersion syndrome
Traumatic hyphaema
Sx AACG (4)
Pain
N+V
Blurred vision
Halo’s
Signs AACG (5)
Brick red eye Cloudy cornea Fixed mid-dilated pupil IOP >21mmHg Closed iridocorneal angle on gonioscopy
3 Mx steps of AACG
Topical
Systemic
Laser Tx
Eye drops used AACG
Timolol
Apraclonidine
Once IOP in AACG is <50 what should you prescribe?
Miotic
Systemic Tx AACG
IV CAH - acetazolamide
IV hyperosmotic e.g. mannitol
Analgesia, antiemetics
When to use laser trabeculectomy in AACG
ASAP in contralateral eye
+ within a week in eye affected
When to use trabeculectomy in AACG?
Resistant cases
