Glaucoma Flashcards
What is glaucoma?
A chronic progressive optic neuropathy characterized by retinal ganglion cell death and cupping of optic nerve head leading to irreversible visual field loss
How is glaucoma broadly classified?
- Primary - open angle & angle closure
- Secondary - open angle & angle closure
Name some secondary glaucoma
- pseudoexfoliative
- pigmentary
- neovascular
- inflammatory
- traumatic
- steroid induced
What causes increased IOP in POAG?
Increased resistance to aqueous outflow at the trabecular meshwork
What structure in responsible for aqueous humor drainage?
Trabecular meshwork
Schlemm’s Canal
What is the normal IOP range?
10-21 mmHg
Can glaucomatous damage occur at normal IOP?
Yes, in normal tension glaucoma (NTG)
Name the risk factors of POAG
- high IOP
- age > 40
- family history
- thin central corneal thickness
- myopia
- DM, HTN
- corticosteroids use
What are the risk factors for PACG?
- hyperopia
- shallow anterior chamber
- female sex
- older age
- lens enlargement
What are the early symptoms of POAG?
Usually asymptomatic
- late stage vision loss (peripherally)
What are the symptoms of PACG?
- sudden onset pain
- redness
- blurred vision
- halos around lights
- H, N, V
What optic disc changes occur in glaucoma?
- increased cup to disc ratio
- vertical elongation of cup
- notching of neuro retinal rim
- disc hemorrhages
What is the ISNT rule in glaucoma?
normal rim thickness order
- inferior > superior > nasal > temporal
Disrupted in glaucoma
What is the typical visual filed defect in POAG?
- arcuate scotomas
- nasal steps
- paracentral scotomas
- peripheral field constriction
Which visual field is affected first in glaucoma?
Peripheral visual field
What is the golden standard for measuring IOP?
Goldmann applanation tonometry
What is gonioscopy used for?
To assess the angle between the iris and cornea
& differentiate open vs closed angle glaucoma
What is Optical Coherance Tomography (OCT) used for in glaucoma?
To assess retinal nerve fiber layer (RNFL) thickness and optic nerve head
How often should IOP be monitored in glaucoma patients?
Regularly, as per disease severity (every 3-6 months)
What are the differential diagnosis?
- optic neuritis
- ischemic optic neuropathy
- compressive optic neuropathies
What is the primary goal of POAG?
To lower IOP and prevent progression of optic nerve damage
What is the 1st line medical treatment in POAG?
Prostaglandin analogue
How do prostaglandin analogs work?
Increase uveoscleral outflow
Name side effects of prostaglandin analogs.
- conjunctival hyperemia
- eyelash growth
- iris pigmentation
How do beta blockers reduce IOP?
Decrease aqueous humor production
Why are beta blockers contraindicated in asthma?
They can cause bronchospasm
How do alpha-2 agonist work?
Decrease aqueous production and increase uveoscleral outflow
What is the mechanism of carbonic anhydrase inhibitor?
Reduce aqueous production
What are side effects of systemic CAIs (e.g acetazolamide)?
- Paresthesias
- GI upset
- kidney stones
- electrolytes imbalances
What are the role of mitotic like pilocarpine?
Increase trabecular outflow by contacting the ciliary muscle
When is laser trabeculoplasty indicated?
In patients with POAG who do not respond to or cannot tolerate medications
What is trabeculectomy?
Surgical creation of fistula from the anterior chamber to subconjunctival space for aqueous drainage
What are glaucoma drainage devices used for?
In refractory cases or failed trabeculectomy
What is cyclophotocoagulation?
Destruction of ciliary body to decrease aqueous production (used in advanced/refractory cases)
What is the immediate treatment for acute angle closure glaucoma?
IV acetazolamide
Topical beta blocker
Pilocarpine (after IOP reduction)
Hyperosmotic agents
What is the definitive treatment in PACG?
Laser peripheral iridotomy in both eyes
