Abstract
Purpose: :
To investigate the correlation between structure and function using scanning laser tomography, flicker defined form (FDF) perimetry and standard automated perimetry (SAP).
Methods: :
The sample consisted of 119 participants with early to moderate glaucoma (mean age 63.49 ± 9.22 years, Male/Female ratio=0.83h). One eye of each participant was randomly assigned if both eyes were eligible for the study (60 OD). The study consisted of 3 visits over a 6 week period and included standard automated perimetry (SAP, 24-2 ASTA-Std; visits 2 and 3) and flicker defined form perimetry (FDF 24-2 ASTAStd; all visits) on the Heidelberg Edge Perimeter (HEP; Heidelberg Engineering (HE)). Scanning laser tomography images of the optic nerve were acquired on the first 2 visits. Unreliable HEP visual fields and poor quality images on the HRT were excluded from the study. The SAP/FDF visual fields were divided into sectors corresponding to the six HRT Moorfields regression analysis sectors. The relationship between global and sectoral HRT parameters and the mean deviation (MD) of FDF and SAP were analyzed using correlation coefficients and linear regression. Kappa analysis was used to score the agreement between global and sectoral classifications, i.e WNL, BL and ONL.
Results: :
The mean MD of FDF and SAP were -7.46 ±5.39 dB and -2.97±2.34 dB. There was significant correlation between the FDF and SAP MD and HRT rim area, cup shape, rim volume, cup to disc ratio and FSM discriminant function measured by the HRT (P<0.001), with FDF always giving higher correlations. For example, the correlation between HRT rim area and FDF/SAP MD were (r-value): Global: 0.45/0.26, sup tmp: 0.44/0.32, tmp: 0.31/0.18, inf tmp: 0.56/0.38, sup nsl: 0.37/0.30, nsl: 0.24/0.05, inf nsl: 0.31/0.19). Kappa analysis showed fair agreement between FDF and HRT classifications. The Kappa score was always less for SAP. For example, sup tmp: k=0.28(FDF), 0.16(SAP); inf tmp: k=0.33(FDF), 0.32(SAP).
Conclusions: :
FDF perimetry correlated better with scanning laser tomography than SAP in this sample of patients with early to moderate glaucoma.
Keywords: perimetry • optic nerve • visual fields