RETINAL NERVE FIBER LAYER CHANGES IN UNAFFECTED MATERNAL RELATIVES OF PATIENTS WITH LEBER’S HEREDITARY OPTIC NEUROPATHY

Abstract

Abstract: : Purpose: To investigate by Optical Coherence Tomography (OCT3) measurements the Retinal Nerve Fiber Layer (RNFL) thickness in Unaffected Maternal Relatives (UMR) of patients affected with Leber’s Hereditary Optic Neuropathy (LHON). Methods: 63 UMR (21 males and 42 females) carrying one of the three common pathogenic mtDNA mutations (nucleotides 11778, 3460 and 14484) were investigated in comparison with an age–matched control group of 70 individuals (30 males and 40 females). OCT3 was used to detect the peripapillary RNFL thickness (3.4mm diameter scan). One randomly selected eye was considered for each patient and control individual. Groups were compared by one–way analysis of variance. Results: Average RNFL thickness was increased in UMR males (p = 0.02) but not in females. UMR males showed a thicker RNFL in the temporal (p = 0.03) and inferior (p = 0.01) quadrants, while UFR females showed a thicker RNFL only in the temporal quadrant (p = 0.006). Measurements of the remaining quadrants did not reveal significant differences. Stratifying by mutation our data, the RNFL thickness increase was detected only in UMR carrying the 11778 mutation, while no differences were found for the 3460 mutation subgroup. Conclusions: The study showed that the peripapillary RNFL is thickened in UMR; this alteration occurs preferentially in males, involving prominently the temporal quadrant, which relates mainly to the small fibers of the papillomacular bundle. These findings suggest some axonal swelling, which may indicate an early stage of RNFL damage in absence of clinical symptoms. Furthermore, this feature seems to be more specific for the most common LHON mutation at position 11778. OCT3 is a useful tool to follow early stages of LHON in unaffected carriers.

Keywords: neuro–ophthalmology: optic nerve • nerve fiber layer • mitochondria