PMC4125372_01
Color wash and dose-volume histogram.. Note: The radiation dose distribution at the optic chiasm (red solid line), and the left (green solid line) and right (purple solid line) optic nerves are shown in a color wash (A) and dose-volume histogram (B).
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The radiation dose to gross primary tumor and positive lymph nodes in the neck, high-risk region, and low-risk elective nodal region were 70 Gy, 60.3 Gy, and 54 Gy, respectively. IMRT was delivered with 30 daily fractions in 6 weeks (five fractions per week). The maximal radiation dose to the optic chiasm and the left and right optic nerves were 32.1 Gy, 16.7 Gy, and 17.7 Gy, respectively (Figure 1).
Flash visual-evoked potential and electroretinogram results.. Notes: During flash visual-evoked potential (A and B), and electroretinogram (C), there was no waveform observed in the left eye (A and C), but a normal wave was found in the right (B and C). SYSN means the synchronic signal was used during the information acquisition. N75, P100 and N145 are three different waves in pattern visual-evoked potential.. Abbreviations: L-frequency, low frequency; H-frequency, high frequency; SYSN, synchronous signal.
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The pattern visual-evoked potentials (VEPs) and transient, flash electroretinograms (ERGs) were abnormal (Figure 2A and C). Non-specific waves were found in his left eye (Figure 2A and C), but the VEP and ERG were normal in his right eye (Figure 2B and C).
Visual field test.. Note: Temporal hemianopsia and a nasal peripheral visual field defect were diagnosed during the right eye visual field study.. Abbreviations: O/O, 0%; POS, positive; NEG, negative; SITA-fast, Swedish Interactive Threshold Algorithms; RX, correction of refractive errors; DS, Diopter sphere; DC, Diopter cylinder; GHT, Glaucoma Hemifield Test; VFI, visual field index; MD, mean defect; PSD, pattern standard deviation.
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The right eye had a normal visual field; the left eye visual field could not be assessed due to its loss of light perception (Figure 3). A temporal hemianopsia, and a nasal peripheral visual field defect were found in the right eye (Figure 3).