The Effect of Pupil Dilation on Scanning Laser Polarimetry with Variable Cornea Compensation
E.Z. Blumenthal, A. Horani and S. Frenkel
Invest Ophthalmol Vis Sci 2004;45: E-Abstract 3311. © 2004 ARVO 3311 – B946
Dept of Ophthalmology, Hadassah University Hospital, Jerusalem, Israel
Commercial Relationships: E.Z. Blumenthal, Laser Diagnostic Technologies F; A. Horani, None; S. Frenkel, None.
Grant Identification: none
PURPOSE: Scanning laser polarimetry is routinely performed through a non–dilated pupil, since scanning through dilated pupils might contribute to off–axis scanning, and hence, erroneous cornea compensation, reducing test accuracy and reproducibility. We tested the feasibility and reproducibility of scanning through dilated pupils.
METHODS: One eye each, of 36 subjects (12 normal, 12 glaucoma suspects and 12 glaucoma patients) was scanned using the GDx with a variable cornea compensator (GDx–VCC). Two scans prior to, and two scans after dilation were performed on each study eye, resetting the cornea compensation prior to each of the scans. Each of 5 GDx parameters was evaluated separately, comparing the two pre–dilation to the two post–dilation scans.
RESULTS: Of the 5 GDx–VCC parameters evaluated, none showed a statistically significant difference when comparing the pre– to the post–dilation measurements. The two groups showed a high pre– to post–dilation correlation: 98%, 98%, 98%, 93%, and 95% for The Number, TSNIT Avg, TSNIT SD, Superior Avg, and Inferior Avg, respectively. Under 5% of the measurement variability was attributed to changes in pupil size (R–squared: 0.024 to 0.047). Stratifying the data by diagnostic groups yielded similar results.
CONCLUSIONS: Pharmacological mydriasis does not appear to significantly alter the RNFL measurements acquired using the GX–VCC instrument. Scanning dilated patients using the GDx–VCC produced results found to be comparable to scans achieved in the same eyes prior to dilation.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • clinical (human) or epidemiologic studies: systems/equipment/techniques