Structure-Function Relationship in Patients with Glaucoma Suspect: Diagnostic Value and Changes During Follow-up

OBJECTIVES: To evaluate anatomical and functional changes during follow-up in eyes with glaucoma suspicion.
METHODS: A total of 56 eyes of 28 patients (F/M: 21/7) who were included. Detailed ophthalmologic examination, optic coherence tomography (OCT) and visual field (VF -SITA 24-2 and 10-2) were performed at the initial and 12th month examination. Retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thicknesses, 24-2 VF global indices (MD, PSD), and 10-2 VF superior and inferior hemi-quadrant mean sensitivities (dB) were recorded. The presence of "cluster defect" was noted in both VFs.
RESULTS: The mean age was 56.1±10.8 (34-74) years, mean IOP was 18.2±3.8 mmHg and mean cup/disc ratio (C/D) was 0.4±0.2 at the first visit. There was no significant change in mean IOP and C/D during the follow-up (p=0.655, 0.988, respectively). No significant progression was observed in OCT and VF parameters (p>0.05 for all). At the initial examination, a mild positive correlation was found between total RNFL, GCC and 24-2 MD (r=0.292, 0.316, respectively). At the 12th month, there was a moderate positive correlation between total RNFL and 24-2 MD (r=0.317) and a moderate negative correlation between total RNFL and PSD(r=-0.327). No correlation was observed between 10-2 VF superior/inferior hemi-quadrant mean sensitivity (dB) and inferior/superior RNFL and GCC in both examinations (p>0.05 for all). Cluster defect was present in 35 eyes at initial examination and in 30 eyes at 12th month.
DISCUSSION AND CONCLUSION: There’s not a single parameter that can be used to differentiate glaucoma suspects from early-stage glaucoma. VF, RNFL and GCC should all be evaluated, and longer follow-ups are necessary.

Keywords: Glaucoma suspect, retinal nerve fiber thickness, ganglion cell complex, visual field, cluster defect