Visual Field Progressive Rate in Normal Tension Glaucoma Before and After Trabeculectomy: A Subfield-Based Analysis

Area of Science:

• Ophthalmology
• Glaucoma Research
• Surgical Outcomes

Background:

• Normal-tension glaucoma (NTG) is characterized by progressive visual field loss despite normal intraocular pressure (IOP).
• Trabeculectomy is a surgical procedure to reduce IOP and prevent further vision loss.

Purpose of the Study:

• To compare pre- and post-trabeculectomy visual field progression rates in NTG patients.
• To analyze progression in six specific subfields of the central visual field.

Main Methods:

• Retrospective study of 34 NTG patients with progressive visual field loss.
• Analysis of mean deviation (MD) and total deviation changes using linear mixed-effects models.
• Evaluation of progression rates in superior/inferior arcuate, paracentral, and cecocentral subfields.

Main Results:

• Successful trabeculectomy lowered average IOP to 10.3 ± 2.7 mm Hg.
• The overall rate of visual field progression (MD change) significantly slowed postoperatively (-0.25 dB/y) compared to preoperatively (-0.70 dB/y).
• Progression improved in superior paracentral and arcuate subfields, but remained unchanged in inferior cecocentral/arcuate subfields.

Conclusions:

• Surgical IOP reduction via trabeculectomy significantly slowed visual field progression in NTG.
• The beneficial effect was more pronounced in superior visual field subfields.
• Inferior cecocentral/arcuate subfields showed no significant improvement in progression rates post-surgery.