20-Year Prospect
The BLS predicts 23% job growth in this field over a ten-year period, far above the national average (source). Numerically, that comes to just 15,800 new jobs, which isn't that much, but hey, how many people do you know who have ever even considered a career in opticianry?
Growth is growth. If you take the plunge and get yourself trained as an optician, you're almost sure to be able to find a job. Ninety-eight-plus percent sure, if the going unemployment rate for opticians is any indication (source).
Think of it this way: there are more old people and more sick people in our society than ever before. This will drive job growth in the field, and also lead to a higher proportion of opticians working directly out of a medical office.
That said, technology and medical advances are also driving productivity, which means that fewer opticians will be able to treat more patients, which will limit the potential for job growth. It's hard to tell which will win out, but if recent developments are any indication, this career should continue to grow pretty steadily.