Complex sentence: Therefore, systemic intravenous treatment with corticosteroids, which may quicken the healing of the optic nerve, is often recommended, but it does not have a significant effect on the visual acuity at one year, when compared against placebo.
Split into simpler sentences: Therefore, systemic intravenous treatment with corticosteroids, which may quicken the healing of the optic nerve, is often recommended. It does not, however, have a significant effect on the visual acuity at one year when compared against placebo.