Last year's difficult market meant many stocks struggled -- even those with bright future prospects. That's why we shouldn't consider all of these players troubled and turn our backs on them. Instead, we should look at stocks individually. And if we do this, we're likely to find some great buying opportunities today -- and identify stocks to avoid too.

By buying opportunities, I mean stocks that look dirt cheap right now considering potential earnings down the road. The stocks to avoid are those that don't yet have a clear path to growth. There are plenty of examples of both in the world of healthcare. So let's check out two struggling stocks to buy hand over fist right now, and one to avoid like the plague.

Stock to buy: Teladoc Health

Teladoc Health (TDOC 2.46%) sank 74% last year -- and for one particular reason. The telemedicine giant reported two billion-dollar noncash goodwill impairment charges. Both were linked to the acquisition of chronic-care specialist Livongo.

Investors have been eager for the company to transform growing revenue into profitability. But after it announced the impairment charges, that goal seemed even farther away.

In the third quarter, though, Teladoc gave us reason to be optimistic. The company didn't report further impairment charges, and its net loss narrowed. At the same time, Teladoc has continued to report double-digit growth in revenue and visits. Things are looking bright for the full year too: The company recently raised its full-year revenue forecast.

Teladoc is a leader in an industry that's growing by double digits. And the Livongo purchase should eventually pay off -- almost half of Americans suffer from at least one chronic illness. All of this means that Teladoc, trading at its lowest multiple to sales ever, looks like a steal right now.

Stock to buy: Moderna

Moderna (MRNA 3.01%) shares declined in 2022 -- but they've been on the rise so far this year, and for good reason. The company has given us positive news about the potential post-pandemic coronavirus vaccine market. And Moderna has made progress advancing late-stage programs in its pipeline.

Here's a quick look. Moderna expects a post-pandemic vaccine market in the range of $12 billion to $24 billion. The company also has spoken of charging up to $130 for its vaccine; that's up from about $25 today. So it's clear Moderna may generate recurrent blockbuster revenue from annual coronavirus boosters -- even if demand is much lower than it was earlier in the pandemic.

At the same time, Moderna may launch additional products. The company aims to bring to market its influenza and respiratory syncytial virus vaccines in the next couple of years; these represent billion-dollar markets.

The biotech has a total of 48 programs in development across many therapeutic areas. If even a handful are successful, we could be looking at major earnings down the road. All of this means Moderna's growth story may just be getting started. And now is the time to jump on board.

Stock to avoid: Ocugen

Ocugen (OCGN -6.06%) soared earlier in the pandemic on hopes it would bring a coronavirus vaccine to market. The company has U.S. and Canada commercialization rights to Covaxin, developed by India's Bharat Biotech. The problem is that these countries haven't yet authorized Covaxin -- so Ocugen isn't generating vaccine revenue.

And even if the U.S. and Canada authorize Covaxin down the road, it won't be easy for a latecomer to carve out market share in what may be a post-pandemic world.

But what about the rest of the pipeline? Ocugen has expanded its focus from gene therapies to treat eye diseases, to include an asset it acquired as part of its reverse merger with Histogenics in 2019. That's NeoCart, for the repair of knee-cartilage lesions.

At Histogenics, NeoCart missed the primary endpoint of its phase 3 trial. Other results were compelling, though. So NeoCart -- and Ocugen -- could potentially succeed in an upcoming new phase 3 trial. As for the eye disease candidates, they remain in earlier stages of development.

To support these programs, research and development costs are climbing; they more than doubled year over year in the third quarter. At the same time, Ocugen's path to revenue isn't clear. So, right now, Ocugen is at the top of my "stocks to avoid" list.