The onset of visual disturbance is unpredictable and can occur within weeks of starting treatment (or sooner) or at any time during treatment, even after months or years.

• 视觉紊乱的发病难以预测，可在开始治疗后的数周内（或更早）或治疗期内任何时间发生，甚至还可在数月或数年后发生。