They told me "you have 20/20 vision, your vision is completely fine, you don't need glasses!" But, I responded, my vision is definitely blurry. They politely told me to stop wasting their time.
Dissatisfied, I went to another optometrist, and paid closer attention to the whole process. After some discussion with the doctor, we arrived at the conclusion - I've had essentially 20/7 vision my entire life, and now in certain circumstances my vision has degraded to 20/20!
They gave me a prescription and now I am perfectly happy having laser-sharp vision again when I want it.