Abstract
Purpose::
To investigate the different effects of cataract operation on brightness of fundus autofluorescence (FAF) between a fundus camera (FC) and a confocal scanning laser ophthalmoscope.
Methods::
Twenty-eight eyes of 20 sequential cataract patients consisting of 12 males and 8 females with no abnormality of the posterior pole were examined. The mean age was 73.8 years (range 61-83 years). FAFs of the posterior pole were taken with a Topcon TRC-50AX fundus camera (Topcon, Tokyo) and a Heidelberg retina angiograph 2 (Heidelberg Engineering, Heidelberg) (HRA2). FAF images were taken in the same condition pre- and one-week post-operatively for both instruments. For HRA2, averaging of sequential FAF images was done for noise reduction. FAF brightness was evaluated as a gray scale in each pixel by 256 grades ranging from 0 to 255 by using software "Scion image" (Scion Corp.). The average, standard deviation and range of the FAF brightness were measured at a circle area within 10 degrees of the fovea. The Statistical difference of the pre- and post-operative FAF brightness was determined by two-sided paired t test. Difference with P<0.05 was considered significant.
Results::
The average grades of FAF brightness statistically decreased from 129.0 to 57.8 for FC (P<0.001), but statistically increased from 59.8 to 102.0 for HRA2 (P<0.001). For FC, the standard deviation and the range of FAF brightness changed from 11.1 to 9.97 (P=0.20) and from 78.5 to 72.5(P=0.27) (P=0.27), respectively. For HRA2, the standard deviation and the range of FAF brightness statistically increased from 17.2 to 32.5 (P=0.001) and from 145.6 to 218.1 respectively (P=0.001).
Conclusions::
FAF brightness decreased for FC and increased for HRA2 after cataract operation. Contrast of FAF image, determined by the standard deviation and brightness range, showed no change for FC, but increased for HRA2. Cataract would produce different effects on FAF brightness according to the optical system of the FAF instruments used.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • cataract • imaging/image analysis: clinical