Prospective Comparison of Global and Cluster Visual Field Progression Criteria in Glaucoma and Their Relationship to Structural Changes

Abstract

Purpose : Average threshold in visual field clusters has been proposed as an improved method for identifying early progression in glaucoma. This study aims to evaluate the prognostic capabilities of the Cluster Analysis (CA) in comparison to global visual field indices and structural measurements.

Methods : 8 patients with a diagnosis of glaucoma, glaucoma suspect or ocular hypertension were prospectively enrolled in this study. Patients were assessed with Humphrey Visual Field (HVF), Heidelberg Retinal Tomography (HRT3), and Spectral Domain Optical Coherence Tomography (SD-OCT) during 5 visits over a period of 2 years. Mean Deviation (MD), Visual Field Index (VFI), and Linear regression analysis of the mean threshold in each of the clusters defined by the Glaucoma Hemifield Test (GHT) were used to compute rate of progression. Rates of change in rim area (RA, HRT3) and OCT RNFL (Retinal Nerve Fibre Layer) analysis were also assessed and correlated with CA. Rates of progression were defined as significant if the gradients over time were negative with p<0.05.

Results : HVF CA showed significant progression in 11/16 eyes with an average rate of progression of -2.18±2.2dB/year, p<0.005 where Cluster 4 was the most frequently involved (6 eyes). RNFL was also found to be significantly thinner with OCT analysis in 12/16 eyes with an average rate of progression of 2.58±1.43μm/year, p<0.001. Rim Area was affected in 7/16 eyes (-0.2±0.1 mm²/year, p>0.05) while 6 /16 and 5/16 were progressing with VF MD (-0.21±0.22dB/year, p<0.05) and VF VFI (-0.60±0.63%/year) respectively. The best agreement between different techniques was between CA and OCT RNFL (k=0.61). Overall sensitivity of each test was: OCT 75%, CA 68%, HRT 44%, VF MD 37%, and VF VFI 31%.

Conclusions : Together these results suggest that CA could be a useful tool to identify early progression and with a greater sensitivity than global indices (MD and VFI) with a better concordance with structural changes especially in the early stage of the disease. CA may therefore provide a new and more sensitive technique for monitoring glaucoma progression and facilitate better disease management though more timely interventions.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

The 54 test points of the HFA 24-2 SITA Standard were classified into 10 clusters. Cluster 4 (green) was the most frequently progressing