VSP is the most popular vision insurance company in the nation, and, because of that, its coverage is easy to use. Around 137,000 eye doctors and offices take VSP insurance, including 41,000 retail locations like Walmart, Sam's Club and Costco. VSP also has good discounts for laser eye surgery, like LASIK.

VSP offers three plan levels — EasyOptions, Standard and Enhanced — and lets you customize them to your needs. For example, you could choose a $150 allowance for glasses frames or upgrade your policy to a $230 allowance. If you don't wear glasses, you can choose a plan that just covers contacts.

VSP is the largest vision insurance company in the United States by far. About two-thirds of people with standalone vision insurance policies have coverage from VSP, and even more people have coverage through their jobs.

Going with a popular company has its perks. Because VSP is so popular, it's likely that your eye doctor takes the insurance. However, there are some concerns about how VSP operates behind the scenes, and that its large size may be harming healthy competition in the vision insurance space.

VSP's plans can get expensive, though, with higher-coverage options costing up to $30 per month or more, depending on where you live. And VSP has lower-than-average customer satisfaction according to J.D. Power.

If you want both vision and dental insurance, Blue Cross Blue Shield is a good option. Anthem, the largest BCBS company in terms of vision insurance, offers several levels of vision plans. All the plans come with coverage for an annual eye exam. You can choose how much coverage you want for your eyewear, ranging $80 to $200 for contacts and from $130 to $200 for glasses frames. No matter what option you choose, you'll never pay more than $20 for your glasses lenses.

Anthem also offers both individual and family dental insurance plans. The deductibles are usually low, which means you won't have to pay much before your coverage starts. And if you have a large family, you won't pay rates for more than three of your children.

BCBS companies typically have good customer service, but it depends on the company where you live. Before you buy a plan, research your local company to make sure it has good customer service.

But each Blue Cross Blue Shield company has its own plans, and not all BCBS companies offer standalone vision and dental coverage. You'll have to check the Blue Cross Blue Shield company where you live to see if you can buy vision and dental coverage.

Humana's Vision PLUS plan has good coverage on multi-focal lenses, like bifocals and trifocals, which makes it especially good for seniors. If you stay in the network, you'll only pay $10 for a pair of bifocal or trifocal lenses. The PLUS plan also gives you up to $250 for glasses frames if you use the PLUS plan network. If you want contacts instead of glasses, you'll get up to $200 to put toward them.

However, Humana doesn't sell regular health insurance anymore. This isn't ideal if you want to use the same company for your health and vision insurance and you don't yet qualify for Medicare.

But Humana does sell Medicare Advantage plans for seniors, which often come with vision benefits built in.

EyeMed offers three levels of vision insurance plans, and the cheapest one starts at just $5 per month. The EyeMed Healthy plan is a good, cheap option if you just want coverage for an annual exam, plus discounts to help make glasses or contacts cheaper. However, you'll still have to pay for your glasses and contacts yourself.

But EyeMed plans don't start until at least a week after you buy the policy. If you need coverage right away, Humana is a better option.