When 3D TVs were introduced in 2009, it seemed only a matter of time until we would all be wearing sunglasses at night.

But things change at laser speed in the $190 billion-per-year consumer-electronics industry.

Now, despite steep holiday discounts, the enhanced 3D models are struggling to hold on to market share.

The special-effect sets - which sell for $1,000 to $4,000 - are prisoners of their own technology.

"As the prices have come down, the new barriers [for customers] are the unavailability of 3D content and the fact that people think the glasses are expensive and inconvenient," says Andrew Eisner, director of content for Retrevo, a consumer-electronics review website.

Both issues are being addressed, albeit remedially.

The Blu-ray release of Avatar kick-started 3D TV sales, as viewers rushed to reexperience the film the way Eywa, the Na'vi deity, intended.

The subsequent trickle of 3D events has made it difficult to justify the expense of buying a set, but that is changing.

This month, for instance, ESPN's 24/7 3D channel will carry four college football bowl games.

And the all-3D channel, 3net, a joint venture of Sony, IMAX, and Discovery, is offering Fields of Valor, a four-part Civil War documentary that may be the most ambitious 3D made-for-TV program to date. (In the Philadelphia area, 3net is available only to DirecTV subscribers.)

Both ventures present headaches.

ESPN has only two of the superexpensive production trucks needed for 3D transmission, which puts a lot of wear on their tires as they crisscross the country.

"The logistics . . . it's like playing three-dimensional chess," says Bryan Burns, vice president of strategic business planning at ESPN. "We've learned how to be very efficient at what we're doing."

Fields of Valor stockpiled enough unusable footage to build its own full-size replica of Fort Sumter with it.

The cameras used for 3D are equipped with two lenses that shoot the same image simultaneously. If anything disrupts one or both of the shots, it ruins the depth of field and can literally give the viewer a headache.

Try maintaining precise equilibrium during a massive Civil War battle reenactment.

"Say you're shooting someone 30 feet away and someone runs in front of the camera. You have to eliminate that shot," says Dave Less, a film editor at Tower Productions who worked on the documentary.

Surveys show that 3D TV owners use the sets primarily to watch Blu-rays of feature films and wildlife docs. But gamers are being drawn in by the new 3D titles available for Sony PlayStation 3 consoles.

The other big turnoff for TV buyers is the glasses needed to create the effect. Each manufacturer makes its own set of polarized goggles, which are surprisingly heavy and unwieldy.

Unless you're a hermit, you're going to want to stock up on several for family and friends. At roughly $150 each, that ain't chicken feed.

A few of the second generation of 3D sets that recently hit the market use a different optical method ("passive") to create a slightly more superficial 3D illusion. But at least the glasses, which resemble those they hand out at the cineplex, are lighter and cheaper.

But having two competing 3D delivery systems on sale could make consumers more hesitant to buy.

Progress is being made on 3D sets that can be enjoyed with the naked eye, but that intriguing innovation is at least three years away.

There are a few last caveats for the emptor. If you're going to buy one of these puppies, you'll probably want to get maximum bang with one of the pool-table-size sets. That usually entails an installation fee to mount it on your wall.

That's not the only hidden cost. "You'll need to buy a specific kind of cable, an HDMI cable to go from your cable box to the TV, or the process won't work," says Ted Minda, a customer-solutions manager at Best Buy in King of Prussia. "Blu-rays only come equipped with composite cables, so you'll need to buy another HDMI cable for that. The starting price for those is $69.99."

Of course, if the studios and the TV programmers create enough can't-miss events in 3D, viewers are far more likely to take the plunge.

"We have a saying: Software sells hardware," Eisner says. "3D needs a few blockbusters, the Super Bowl, the Oscars. Then you'd see TV sales pick up."

3D had better secure some big guns and roll them out fast, because consumer electronics evolve relentlessly.

TV manufacturers and marketers are already gearing up for the introduction next year of 4K sets, which promise images with four times the clarity and resolution of the best HDTVs currently available.

You can be sure of one thing: The new models will come with a hefty price tag.

Contact television writer
David Hiltbrand at 215-854-4552, dhiltbrand@phillynews.com, or @daveondemand_tv on Twitter. Read his blog, "Dave on Demand," at www.philly.com/dod.