Comparison of optical coherence tomography and scanning laser polarimetry measurements in patients with multiple sclerosis

Abstract

Purpose: To compare optical coherence tomography (OCT) and scanning laser polarimetry (GDx) measurements of the retinal nerve fiber layer (RNFL) in multiple sclerosis (MS) patients with and without optic neuritis (ON).

Methods: OCT and GDx were performed on 68 MS patients. Qualifying eyes were divided into two groups: 51 eyes with an ON history > or =6 months before (ON eyes) and 65 eyes with no history of ON (non-ON eyes). Several GDx and OCT parameters and criteria were used to define an eye as abnormal, for example, GDx nerve fiber indicator (NFI) >20 or 30, OCT average RNFL thickness, and GDx temporal-superior-nasal-inferior-temporal average (TSNIT) below 5 or 1% of the normative database of the instruments. Agreement between OCT and GDx parameters was reported as percent of observed agreement, along with the AC1 statistic. Linear regression analyses were used to examine the relationship between OCT average RNFL thickness and GDx NFI and TSNIT.

Results: All OCT and GDx measurements showed significantly more RNFL damage in ON than in non-ON eyes. Agreement between OCT and GDx parameters ranged from 69 to 90% (AC1 0.37 to 0.81) in ON eyes and 52 to 91% (AC1 = 0.21 to 0.90) in non-ON eyes. Best agreement was observed between OCT average RNFL thickness (p < 0.01) and NFI (>30) in ON eyes (90%, AC1 = 0.81) and between OCT average RNFL thickness (p < 0.01) and GDx TSNIT average (p < 0.01) in non-ON eyes (91%, AC1 = 0.90). In ON eyes, the OCT average RNFL thickness showed good linear correlation with NFI (R = 0.69, p < 0.0001) and TSNIT (R = 0.55, p < 0.0001).

Conclusions: OCT and GDx show good agreement and can be useful in detecting RNFL loss in MS/ON eyes.

Figure 1

Scatter plots and linear regression between OCT average RNFL thickness (µm) and GDx NFI (top), GDx TSNIT average (bottom). Solid line delineates regression for ON eyes, and dashed line for non-ON eyes. In the top figure, R² is 0.69 (P < 0.0001) for ON eyes, and 0.37 (P < 0.0001) for non-ON eyes. In the bottom figure, R² is 0.55 (P < 0.0001) for ON eyes, and 0.31 (P < 0.0001) for non-ON eyes.

Figure 2

Scatter plots and linear regression between the time since last ON attack and three parameters: GDx NFI (open triangles and solid line in top figure), GDx TSNIT average (crosses and dashed line in top figure), and OCT average RNFL thickness (bottom). The slopes and the P values for the regression lines are − 0.02 (P = 0.62), 0.00 (P = 0.52), and 0.00 (P = 0.91) for GDx NFI, GDx TSNIT average, and OCT average RNFL thickness, respectively.