Two-tailed unpaired t-test was used to compare FERG 1F amplitude between the two groups and to compare BCVA and FERG amplitude between STGD1 patients with or without foveal involvement.
FERG was recordable in all patients of both study groups.
Interestingly, while FERG 1F amplitude was significantly reduced (<1 [mu]V) in all patients with STGD1, six patients (18%), due to foveal sparing, had a good visual acuity ([greater than or equal to] 0.8) in one or both eyes despite a remarkable interruption of EZ (Figure 2).
FERG 1F amplitude was negatively correlated with the extension of EZ interruption ([R.sup.2] = 0.54, p = 0<0001) (Figure 3) and positively correlated with AMT ([R.sup.2] =0.16, p = 0.02).
Interestingly, no differences were noted regarding FERG 1F amplitude, BCVA, and OCT parameters between patients with early or late onset or with different molecular mutation severity (p > 0.05 for all analyses).
The aim of our study was to explore the correlation between functional and anatomical photoreceptor alterations in patients with STDG1, as evaluated by FERG and SD-OCT, respectively.
Conversely, FERG 1F amplitude showed a significantly negative correlation with the extent of EZ loss and was markedly altered also in cases with foveal sparing whereas, in these patients, BCVA was largely preserved.
Hence, these findings suggest that FERG recording may be a useful adjunct tool to increase the accuracy of patient's selection in promising future clinical trials.
Interestingly, even if FERG fundamental harmonic amplitude was also correlated with AMT, this correlation was notably weaker.
In summary, FERG recording is significantly altered in STDG1 and has an optimal diagnostic accuracy in detecting Stargardt disease.
Hogg, "Clinical and experimental evidence that the pattern electroretinogram (PERG) is generated in more proximal retinal layers than the focal electroretinogram (FERG)," Annals of the New York Academy of Sciences, vol.
Caption: Figure 1: ROC curve showing diagnostic accuracy of FERG 1F amplitude in detecting Stargardt macular dystrophy.