The Collaborative Normal Tension Glaucoma Study (CNTGS)

Pearls Manager: Andrew Tatham

The CNTGS compared treatment versus no treatment in patients with normal tension glaucoma who had verified progression or a visual field defect threatening fixation. 140 patients were randomised. The treatment goal was a 30% reduction from baseline IOP if using medications but for patients undergoing surgery a 20% reduction was accepted. Progression (as evident from changes to visual fields or stereo disc photographs) occurred in 12% (7/61) of treated eyes compared to 35% (28/79) of controls. A beneficial effect of IOP lowering was found only after data were censored for the effect on visual fields of cataract formation. Cataracts were more common in patients treated with surgery. There was wide variation in rates of progression, but untreated eyes had a mean progression rate of 0.41 dB per year.

EGS Guidelines, 4th edition, page 15.

References Anderson DR, Drance SM, Schulzer M. Natural history of normal-tension glaucoma. Ophthalmology 2001;108(2):247-53. Drance D, Anderson DR, Schulzer R. Risk factors for progression of visual field abnormalities in normal-tension glaucoma. Am J Ophthalmol 2001;131(6):498-505. Collaborative Normal Tension Glaucoma Group. The effectiveness of intraocular pressure reduction in the treatment of normal-tension glaucoma. Am J Ophthalmol 1998;126(4):498-505.