Abstract
Purpose:
To analyze the ganglion cell complex (GCC) by optical coherence tomography (OCT) in toxic optic neuropathy and to correlate its thickness and volume with functional damage.
Methods:
We conducted a prospective, case-control study, in healthy subjects and in patients with toxic optic neuropathy, observed in Neurophtalmology section of Centro Hospitalar Lisboa Central. Full ophthalmology examination, OCT (Spectralis ®) and computerized static perimetry were performed. Thickness and macular volume of GCC (retinal ganglion cell layer and inner plexiform layer) were measured after manual segmentation.
Results:
The study included 16 eyes (12 healthy subjects) and 16 eyes (8 patients with toxic optic neuropathy). Age and sex did not differ between the two groups. The etiological factors that generated the neuropathy were: ethambutol (4 patients) and alcohol-tobacco (4 patients). A statistically significant decrease in the thickness and volume of GCC, in all quadrants at 2 and 3mm, was detected in the neuropathy group compared to control (TS2 - p<0,001; TT2 - p=0,009; TI2 - p<0,001; TN2 - p<0,001; TS3 - p<0,001; TT3 - p<0,001; TI3 - p<0,001; TN3 - p<0,001; VS2 - p<0,001; VT2 - p=0,003; VI2 - p<0,001; VN2 - p<0,001; VS3 - p<0,001; VT3 - p<0,001; VI3 - p<0,001; VN3 - p<0,001). A positive correlation between GCC thickness and mean deviation (MD) (TS2 - r=0,880 p<0,001; TT2 - r=0,718 p=0,009; TI2 - r=0,841 p=0,001; TN2 - r=0,837 p=0,001; TS3 - r=0,718 p=0,009; TT3 - r= 0,630 p=0,028; TI3 - r=0,729 p=0,007; TN3 - r= 0,851 p<0,001;) and between GCC volume and MD (VS2 - r=0,770 p=0,003; VT2 - r=0,731 p=0,007; VI2 - r=0,924 p<0,001; VN2 - r=0,838 p=0,001; VS3 - r=0,813 p=0,001; VT3 - r=0,648 p=0,023; VI3 - r=0,729 p=0,007; VN3 - r=0,875 p<0,001) was detected. A negative correlation between MD and time of disease (r=-0,846 p=0,001) and a positive correlation between MD and visual acuity in logMAR (r=0,739 p=0,006) was also obtained. The majority of the structural parameters also correlated negatively with time of disease (p<0,05).
Conclusions:
The decreased GCC thickness and volume detected in this study support the described retinal ganglion cells toxicity. GCC analysis may contribute to the diagnosis and management of this pathology.