“失去视力”常见的英文表达是 lose one's sight 或 become blind。
lose one's sight：强调视力逐渐或突然丧失的过程 ，例如：He lost his sight in an accident.（他在一次事故中失去了视力。）
become blind：侧重于描述最终变成失明这一状态，例如：She became blind due to a rare disease.（她因一种罕见疾病而失明 。）