Influence of subfoveal choroidal neovascularisation on macular imaging with scanning laser polarimetry of the retinal nerve fibre layer.
OBJECTIVE
To investigate the influence of subfoveal choroidal neovascularisation (CNV) on macular imaging performed using scanning laser polarimetry (SLP) of the retinal nerve fibre layer.


METHODS
SLP was performed on 22 consecutive patients with angiographically verified CNV, and on 23 healthy control subjects. One eye per subject was evaluated using the GDx Nerve Fibre Analyser. Regularity of the corneal retardation on the macular SLP images was assessed according to three criteria: (1) magnitude of the 'macular ratio', defined as the ratio of mean retardation values along two axes (the axis with the maximum retardation and the perpendicular one, corresponding in healthy eyes to minimum retardation); (2) the values of GDx parameters which are independent of quadrant position (ellipse modulation and ellipse average); and (3) the frequency of the regular 'bow-tie' polarisation pattern.


RESULTS
'Macular ratio' was significantly higher in the CNV group than in the control group (P<<0.001). Ellipse modulation did not differ between the groups, but ellipse average was higher in the CNV group (P=0.016). The variance for each of these two parameters was significantly higher for the CNV group (P<<0.001 for both comparisons). A 'bow-tie' pattern polarisation was seen in 23 of the 23 control eyes, but only in 7 of the 22 CNV eyes (P<<0.001).


CONCLUSIONS
The results show that CNV influences the macular image obtained with SLP. This suggests that measurements with SLP may be disturbed for eyes with CNV when the customised corneal compensation method, which makes use of the macular retardation image, is employed.
Katsanos
A
A
1st Department of Ophthalmology, Semmelweis University, Budapest, Hungary.
Kóthy
P
P
Papp
A
A
Holló
G
G
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020256:Choroidal Neovascularization / Q000150:complications*; D003430:Cross-Sectional Studies; D005901:Glaucoma / Q000150:complications / Q000175:diagnosis*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007834:Lasers; D008266:Macula Lutea / Q000473:pathology; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology; D012165:Retinal Ganglion Cells / Q000473:pathology*