Evaluation of early changes of macular function and morphology by multifocal electroretinograms in patients with nasopharyngeal carcinoma after radiotherapy
To assess the role of multifocal electroretinograms (mfERGs) and optical coherence tomography (OCT) for detecting early changes in macular functions of patients with nasopharyngeal carcinoma (NPC) after radiotherapy.
mfERGs and OCT were used to examine a NPC group (36 NPC patients after radiotherapy without clinically visible radiation retinopathy, 36 eyes) and a normal control group (25 healthy individuals, 25 eyes) with the same procedure and parameters. The two groups of mfERG were summarized by calculating ring averages, response density, N1 amplitude and P1 and N1 latencies were analysed. OCT scan thickness was summarized into ETDRS regions for comparison.
Compared with controls, the NPC group had significantly decreased P1 response densities in 1–4 ring regions and N1 amplitudes in 1–3 rings (P < 0.01). P1 latencies were obviously prolonged in rings 1 (P < 0.01). In four quadrants (inferonasal, superonasal, inferotemporal and superotemporal) of the mfERG response waveforms, the NPC group had significantly decreased P1 response densities and N1 amplitudes mainly in the inferonasal and inferotemporal quadrants, showing statistically significant differences from the control group (P < 0.0125). But for the OCT results, there is no statistically significant difference between the NPC group and the control group.
In NPC patients after radiotherapy, there may be changes in the mfERGs before any visible fundus lesions appeared as radiation macular oedema. Since the global OCT macular thickness analysis cannot reveal early changes, the mfERGs can objectively and quantitatively assess the earlier changes in macular function in NPC patients.
KeywordsMultifocal electroretinograms Optical coherence tomography Nasopharyngeal carcinoma Radiation retinopathy
Compliance with ethical standards
Conflict of interest
All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and national research committees and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
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