NORMAL TENSION

GLAUCOMA-NTG

Ameerhamza S B 7th term

SIMS , Shimoga

Normal tension glaucoma / low tension glaucoma

Typical glaucomatous disk changes and visual field defects

Intraocular pressure constantly below 21mmHg

The angle of the anterior chamber is open on gonioscopy

No secondary cause for glaucomatous disk changes

Chronic low vascular perfusion makes optic nerve susceptible for normal IOP

This view is supported by - Raynaud phenomenon - Migraine - Nocturnal systemic hypotension and overtreated hypertension - Reduced blood flow velocity in Ophthalmic A.

Etiopathogenesis

IOP : consistently lower than 21mmHgOptic disc changes : Are similar to POAG with following special features - Thinning of neuroretinal rim - Flame shaped haemorrhages of the optic nerve rim (Drance haemorrhage) - Deep, focal notching of the rim  - Peripapillary atrophy

Clinical Features

Visual Field Defects : Similar to POAG but more deeper,steeper,more localised and closure to fixation point

DD’s

High pressure glaucomas

POAG

Glaucoma with intermittent rise in IOP

Previous episodes of Glaucoma

Non glaucomatous optic neuropathies

Congenital optic disc anomalies

Acquired optic neuropathies

Differential Diagnosis

1. Medical Treatment to lower IOP

“Aim is to lower IOP by 30% i.e. to about 12-14mmHg” Betaxolol is DOC because it also increases optic nerve blood flow Drugs with neuroprotective effect like Brimonidine may be preferred PG analogues e.g. latanoprost have greater ocular hypotensive effect in eyes with normal IOP

Treatment

2.Trabeculectomy: When there is progressive field loss occurs despite IOP in lower teens

3.Systemic calcium channel blockers :(e.g.nifedipine) in patients with confirmed peripheral vasospasm

REFERNCE - Comprehensive OPTHALMOLOGY 6th Edition by A.K.KHURANA

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