2Beyoğlu Göz Eğitim ve Araştırma Hastanesi, İstanbul, Uzm. Dr.
3Beyoğlu Göz Eğitim ve Araştırma Hastanesi, İstanbul, Doç. Dr.
4Beyoğlu Göz Eğitim ve Araştırma Hastanesi, İstanbul, Prof. Dr. Purpose: To evaluate the relationship between visual field (VF) indices and retinal nerve fiber layer (RNFL) thickness measurements by optical coherence tomography (OCT), in cases with primary open angle glaucoma (POAG).
Materials and Methods: POAG patients who have medically controlled intraocular pressure, no previous surgery for glaucoma, no ocular obstacle for OCT measurements and who can perform VF testing were included into the study. Optic nerve head measurements were done by Zeiss Stratus ® 3 OCT. SITA 30-2 VF tests were done by Zeiss Humphrey ® device. For each eye, optic nerve head (ONH) parameters in OCT and mean deviation (MD) and pattern standard deviation (PSD) indices in VF test were recorded; and glaucoma staging was done according to MD value. The ONH RNFL thicknesses were compared between the groups; and their relationship with glaucoma stage were analyzed.
Results: A total of 161 eyes of 85 patients were included into the study. Those eyes with MD values ≥-3 dB were classified as “Early stage- Group 1”, between-3 dB and-6 dB were classified as “Moderate Stage-Group 2”, ≤-6 dB were classified as “Advanced Stage- Group 3”. There were 109 eyes in Group 1 (67.7%), 32 eyes in Group 2 (19.9%), 20 eyes with Group 3 (12.4%). In all patients, statistically significant relationship between ONH RNFL thickness and MD value was detected (R=0.240, R2=0.058, p<0.01 Pearson correlation test). There were statistically significant relationship between MD and PSD values in VF test; and mean superior and inferior quadrant RNFL, superior maximum RNFL and ONH-RNFL thicknesses in OCT measurements (p<0.05). The mean ONH RNFL thickness was 97.94±11.06 μ in Group 1, 89.02±21.30μ in Group 2, 88.15±17.95 μ in Group 3. There were statistically significant difference in mean thickness between Group 1 and Group 2, and between Group 1and Group 3 (p=0.029 and p=0.028, respectively); however, there were no statistically significant difference between Group 2 and Group 3 (p=0.876).
Conclusion: A strong correlation between VF indices and OCT RNFL thickness measurements were detected in glaucoma. RNFL thickness in OCT measurements decrease before the VF defect scores. The sensitivity of RNFL thickness measurements by OCT seems to decrease, as the VF defect score deepens.
Keywords : Primary open angle glaucoma, visual field, optical coherence tomography