PRESERVATION OF PHOTIC BLINK REFLEX IN LEBERS HEREDITARY OPTIC NEUROPATHY

Purpose, To examine whether the early response of photic blink reflex (PER) is spared in patients with Leber's hereditary optic neuropathy ( LHON). Methods. Twenty-six patients with bilateral optic neuropathy (v isual acuity less than or equal to 0.1) and central scotomata were div ided into LHON group with one of thr ee mitochondrial DNA mutations at nucleotide position of 3460, 11778, or 14484 and non-LHON group witho ut them. Latencies of the PER early response and those of the electric ally evoked blink reflex (EBR) response were compared among the 26 pat ients and 20 healthy volunteers, Results. In controls, average latency of the PER response was 50.3 +/- 2.4 msec and was in accordance with previous reports. Ten of eleven patients with LI-ION had normal PER re sponses, whereas 12 of 15 controls without LHON had abnormal responses (P = 0.0005). Latencies of EER responses were normal in all but one p atient with LHON. Conclusions. The afferent fibers of the PER early re sponse, as well as those of the light reaction, are reported to termin ate presumably in the pretectum. Together with the reported evidence o f the preserved light reaction in patients with LHON, we presume that W retinal ganglion cells may project common afferent fibers of these t wo neuronal pathways and may be preferentially spared in patients with LHON.