Purpose: To evaluate the relationship between retinal nerve fiber layer (RNFL) thickness measured by spectral-domain optical coherence tomography (SD-OCT) and visual field sensitivity assessed by standard automated perimetry (SAP), and to confirm the diagnostic utility of RNFL measurements in differentiating glaucomatous from non-glaucomatous eyes. Methods: A cross-sectional study was conducted on 64 eyes from 36 individuals attending the Ophthalmology outpatient department at Sree Balaji medical college and hospital, Chennai between November 2023 and December 2024. Eyes were classified as normal, glaucoma suspect or glaucomatous. All subjects underwent comprehensive ocular examinations including SD-OCT and SAP on the same day. Correlation between RNFL thickness and visual field mean sensitivity (MS) was assessed. Diagnostic performance of RNFL parameters was evaluated using receiver operating characteristic (ROC) analysis. Results: Significant thinning of global, superior, and inferior RNFL was observed in glaucomatous eyes ( P < 0.001), with corresponding reductions in the visual field MS. A strong structure-function correlation was found, with the highest correlation between global RNFL and global MS ( r = 0.895, P < 0.001). ROC analysis showed high diagnostic accuracy for RNFL thickness, particularly superior RNFL (area under the curve AUC = 0.973), followed by global (AUC = 0.971), and inferior RNFL (AUC = 0.951). RNFL values below approximately 75 µm were predictive of visual field loss. Conclusion: RNFL thickness, especially in the superior quadrant, demonstrates a strong correlation with functional loss and is an excellent diagnostic parameter for glaucoma. SD-OCT serves as a reliable tool for early glaucoma detection that helps to prevent irreversible vision loss. It also complements perimetric assessment in clinical practice.
Ganesan et al. (Thu,) studied this question.