Reversible structural and functional changes after intraocular pressure reduction in patients with glaucoma

The aim of this study was to evaluate structural and functional improvement following intraocular pressure (IOP) reduction in patients with glaucoma using Spectral Domain Optical Coherence Tomography (SD-OCT), Visual Field (VF) testing, and Visual Evoked Potentials (VEP). A total of 76 eyes from 61 patients underwent SD-OCT, VF and VEP testing. Sixty-two eyes were put in either an acutely high (group 1, IOP > 32 mmHg) or mildly high (group 2, IOP between 22 and 31 mmHg) IOP group and underwent a pressure-lowering intervention. Fourteen eyes with stable glaucoma were controls (group 3, IOP < 22 mmHg). SD-OCT, VF and VEP testing were subsequently performed on all patients at three follow-up visits. Results from these follow-up periods were analyzed for signs of functional and structural improvement. Both group 1 and group 2 patients demonstrated significant decrease in the average cup to disc ratio (p < 0.05) following the intervention. Post-interventional reduction of cup volume was also significant for group 2 patients (p < 0.05). RNFL thickness changes were insignificant. Qualitative grading of VFs by two observers showed improvement in group 1 patients' VFs (p = 0.021). VEP measurements were mostly insignificant, with the exception of High Contrast Latency (LHC) deteriorating for group 2 patients in the first follow-up visit (p = 0.025). This study provides evidence for structural disc cupping reversal following IOP lowering interventions. These changes were not related to the amount of pressure lowering. While there was evidence of functional improvement as measured by VF testing, VEP was unable to detect any reversible changes.