Preperimetric Normal Tension Glaucoma Study: Long-term Clinical Course and Effect of Therapeutic Lowering of Intraocular Pressure

Purpose: The purpose of this study was to investigate the long-term clinical course of normotensive preperimetric glaucoma (PPG).

Methods: The medical records of 71 eyes of 71 patients with normotensive PPG who underwent intraocular pressure (IOP)-lowering therapy were reviewed retrospectively. The patients had been regularly followed up at 3- to 6-month intervals between 1996 and 2011. Progression was evaluated by comparing the structural changes of serial stereoscopic colour disc and red-free retinal nerve fibre layer (RNFL) photographs and by comparing serial visual field (VF) test results for functional changes.

Results: Over an average follow-up period of 6.8 years, 41 eyes (57.7%) showed progression in either structural or functional evaluation. Disc haemorrhage (DH) was observed significantly more frequently in the progressing group (p < 0.005); however, there were no differences in mean age, gender ratio, follow-up period and ocular characteristics at baseline such as IOP, RNFL defects and global indices of VF between the non-progressing and progressing groups. Thirty eyes (42.3%) showed significant angular widening of the localized RNFL defect towards the macula at a mean rate of approximately 1°/year. Perimetric glaucoma developed in 19 eyes (26.8%), and the rate of change in the mean deviation was -0.23 dB/year. Preperimetric glaucoma patients with DH or IOP reductions of <20% from the baseline had a higher probability of RNFL deterioration than patients without DH or IOP reductions of ≥20% from the baseline by multivariate analysis.

Conclusion: Although the rates of change were typically slow, more than half of normotensive patients with PPG showed statistically significant progressive structural or functional changes in medically treated cases. DH or IOP reductions of <20% from the baseline were shown as a significant risk factor for the progression of PPG.