Low Doses of Cyclosporine A Do Not Prevent Second-Eye Involvement in LHON

Data from a recent study published in the Orphanet Journal of Rare Diseases suggests that the administration of oral cyclosporine A (2.5 mg/kg a day) does not prevent second-eye involvement in adult patients with unilateral Leber’s hereditary optic neuropathy (LHON).

LHON is the most common primary mitochondrial DNA disorder and is characterized by painless vision loss that sequentially affects both eyes in a matter of weeks or months and often leads to severe visual impairment or blindness. While LHON typically occurs in young men, it is not exclusive to them.¹

The study sought to evaluate the efficacy of oral cyclosporine A as a preventative treatment in second-eye involvement in LHON patients. Those who were aged 18 years or older with unilateral optic neuropathy that had occurred within 6 months of onset and who had confirmed mitochondrial DNA mutations were eligible to participate. Patients who participated in the study were examined at 3-month intervals over the course of a year.

Among the data collected from each participant at each examination, the primary data included the best corrected visual acuity (BCVA), the mean deviation (MD) of the visual field and the thickness of the perifoveal retinal ganglion cell-inner plexiform layer (GC-IPL) and the peripapillary retinal nerve fiber layer (RNFL) in both eyes.

All 5 of the patients who qualified for and participated in the study (4 males and 1 female) ranged from 19 to 42 years of age (a mean age of 27.2 years and a median age of 26 years). Each participant was given oral doses of cyclosporine A at 2.5 mg/kg a day for 9 months after the initial inclusion or until the occurrence of second-eye involvement. The administered amount categorizes as a low dose used for immunosuppression.

The study’s primary endpoint was to retain the BCVA of the unaffected eye. Secondary endpoints included a change of the BCVA in the first-involved eye along with the mean visual defect on automated perimetry and the thickness of the GC-IPL and RNFL.

According to the results, the period of time between the onset of visual loss and inclusion of the second eye in the study ranged from 7 to 17 weeks. In all 5 patients, the initially unaffected eye became secondarily involved between 11 and 65 weeks, and the first eye that was originally affected worsened.

Over the course of the study in both the first and second eyes affected, the BCVA declined significantly, defects in the MD of the visual fields worsened significantly and the average thickness of the GC-IPL decreased. (However, the thickness of the RNFL showed no significant difference.)

While the study concludes that low doses of oral cyclosporine A at 2.5 mg/kg a day does not prevent second-eye involvement in adult patients with unilateral LHON, it does suggest that the dose could have been inefficient. It also suggests that cyclosporine A treatment could have been administered too late. Since 4 of the 5 patients studied exhibited abnormalities in the second eye in regards to the central visual field at the start of the study, it could be possible that the second eye became affected before the administration of cyclosporine A.

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Reference:

1. “Cyclosporine A Does Not Prevent Second-Eye Involvement in Leber’s Hereditary Optic Neuropathy.” Orphanet Journal of Rare Diseases, 14 Feb. 2018.