Normal tension glaucoma

Question 1

What is normal tension glaucoma?

Answer 1

an optic neuropathy characterised by optic disc evacuation and corresponding visual field loss with open AC angle and normal IOP

Question 2

What are the characteristics of NTG?

Answer 2

IOP < 21mmHg
open angle
absence of any secondary cause for a glaucomatous optic neuropathy
typical optic disc damage (cupping and NNR thinning)
VF defect compatible with the cupping
Progression of glaucomatous damage

Question 3

What is associated with glaucoma?

Answer 3

hypertension
diabetes
cardiovascular and cerebrovascular disorders
vasospastic responses
age
hypercoagulability states
increased local resistance to blood flow

Question 4

What is low OPP?

Answer 4

low ocular perfusion pressure, is a risk factor for glaucomatous damage.
OPP = arterial BP - IOP

Question 5

DDX for NTG?

Answer 5

BRAO
congenital anomalies
optic nerve trauma
demyelinating optic neuritis
intraorbital/intracranial mass
hereditary optic neuropathies
AAION/NAION
myopia
inflammation
infection
compressive optic neuropathy

Question 6

NTG treatment?

Answer 6

prostaglandin analogues
beta-blockers
carbonic anhydrase inhibitors
alpha agonists
Laser trabeculoplasty
surgery

Question 7

What sort of VF loss occurs with NTG?

Answer 7

VF loss from NTG tends to be significantly deeper and closer to the fixation than other types of glaucoma.
nasal step
arcuate scotoma
nerve fibre layer (arcuate) defect bordering horizontal midline