Abstract
Purpose::
To determine whether there is correlation between Scanning Laser Polarimetry Nerve Fiber Index (NFI) and water-drinking test (WDT) response.
Methods::
A retrospective analysis of 49 primary open angle glaucoma patients submitted to Scanning Laser Polarimetry with Variable Corneal Compensator (SLP) and water-drinking test (WDT). All included patients were under same clinical therapy in both eyes and had SLP Nerve Fiber Index (NFI) asymmetry (defined as a minimum 25% difference between both eyes). Differences in IOP measurements before WDT were ≤ 2 mm Hg between both eyes in all subjects. IOP peak and IOP fluctuation obtained with the WDT were compared between eyes. SITA standard achromatic automated perimetry was also performed and compared between eyes by mean deviation (MD) index.
Results::
Better and fellow worse eyes presented mean NFIs of 25.79 +/- 11.01 and 41.87 +/- 19.29 respectively (p<0.0001). Mean visual field MD value was -5.46 +/- 6.36 dB in eyes with higher NFI values and -3.01 +/- 4.67 dB in eyes with lower NFI values (p =0.032). No significant difference between eyes was observed in IOP measurements obtained before WDT. Mean IOP peak after WDT was 21.53 +/- 3.86 mm Hg in eyes with higher NFI and 19.37 +/- 3.77 mmHg in eyes with lower NFI (P = 0.0061). A significant difference in mean IOP fluctuation (maximum IOP - minimum IOP after WDT) was also observed between eyes (5.16 +/- 2.23 mm Hg for eyes with higher NFI versus 3.54 +/- 1.91 mmHg for eyes with lower NFI, p=0.0002)
Conclusions::
Eyes with worse NFI obtained from scanning laser polarimetry presented higher IOP peak and higher IOP fluctuation after water drinking test. This study suggests that glaucomatous eyes with worse structural damage are less able to deal with transient IOP elevation.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • intraocular pressure • visual fields