The Collaborative Normal-Tension Glaucoma Study (CNTGS) demonstrated that reducing IOP by 30% in normal tension glaucoma patients:
- A Halted visual field progression in all patients achieving the target IOP
- B Had no significant effect on field progression compared to untreated controls
- C Reduced the rate of visual field progression by approximately 50%, but some patients progressed despite treatment ✓
- D Improved optic nerve blood flow as the primary mechanism of benefit
Explanation
The CNTGS divided NTG patients into treatment (IOP reduction >30%) and untreated groups. Over 5 years, 35% of untreated patients progressed vs 12% of treated patients — a ~50% reduction in progression rate with treatment. However, a substantial proportion of treated patients still progressed despite IOP reduction, implying non-pressure-dependent factors (vascular dysregulation, optic nerve hypoperfusion, mitochondrial dysfunction, autoimmunity) contribute to NTG pathogenesis. Women and patients with disc haemorrhages at baseline were more likely to progress. This trial established IOP reduction as beneficial in NTG but highlighted its limitations.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.