Researchers recently discovered a distinct pattern of peripheral retinal nerve fiber layer (pRNFL) thinning in Leber’s hereditary optic neuropathy, suggesting some retinal ganglion cells (RGCs) remain viable, even late in the disease state. They noted that pRNFL thinning first occurs in the temporal quadrant, followed by the inferior and superior quadrants and, finally, the nasal quadrant. The pRNFL continued to thin slowly in some quadrants even after 60 months.
The study measured pRNFL thickness in 221 eyes of patients with Leber’s hereditary optic neuropathy and 52 eyes of healthy controls. The researchers divided patients with chronic neuropathy into three groups according to their disease durations: 12 to 24 months, 24 to 60 months and more than 60 months.
Within three months of disease onset, the temporal pRNFL thickness decreased significantly compared with controls, whereas the remaining quadrants and the average pRNFL thickness initially increased. The temporal quadrant and average pRNFL thickness significantly decreased at three to six months compared with controls. Except in the nasal quadrant, the researchers noted that pRNFL thickness significantly decreased in all other quadrants at six to nine months. At nine to 12 months, the average and individual quadrant pRNFL thicknesses continued to decrease.
Compared with the 12 to 24 months chronic neuropathy group, the pRNFL thickness was thinner in the 24-to-60-month group and for those who had the disease for more than 60 months. Since pRNFL thinning continued to occur in some in the chronic stage, the researchers believe viable RGCs were present in these quadrants, still slowly and gradually undergoing apoptosis.
The study found that the papillomacular bundle was affected first and preferentially. The researchers noted that their findings might help practitioners preserve a patient’s visual function better and improve their quality of life. If they actively treat patients with chronic Leber’s hereditary optic neuropathy with longer disease durations, they might preserve the remaining RGCs.
Wang D, Liu HL, Du YY, et al. Characterisation of thickness changes in the peripapillary retinal nerve fibre layer in patients with Leber’s hereditary optic neuropathy. Br J Ophthalmol. August 29, 2020. [Epub ahead of print].