Light Bulbs and Blindness

Question
Hi Pam.

I have two reptiles. One is a juvenile male veiled chameleon. The other is an adult female African-fat tailed gecko.

I've heard that certain light bulbs can cause blindness in reptiles. I was wondering if you could explain this in further detail. I recently had to substitute regular bulbs (temporarily, of course) due to money issues, and was wondering if short term exposure...maybe a week or two...can cause any real irreversible damage.

In addition, can you go into detail about exactly what bulbs to buy? I know there's quite a range of products out there, all for different purposes, but here's what I'm working with:
-My local pet store carries the following brands: Exo-Terra, Zoo Med, and All Living Things.
-My chameleon is in an open-air cage that's about 18" tall, 12" wide, and 12" deep. The gecko is in a glass aquarium...I believe it's 15 gallons (long as opposed to deep).
-The gecko's lighting fixture is a bar light that runs across the top of the cage (similar to a fish tank's lighting fixture). It also has fittings for two regular bulbs. I usually don't turn on the bar light, but instead use a regular bulb and a nighttime infrared bulb in the regular bulb fittings.
-The chameleon's lighting fixture is a clamp lamp suspended above his cage.

I hope I've provided enough information. Thanks in advance for a quick and courteous response.  

Answer
 The best UVB source is the Megaray mercury vapor bulb, next best is the linear fluorescent tube like what you describe that you have.  Reptisun 10.0 or Exoterra Reptiglo 8.0 are good choices for the linear.
 If you go to ReptleUV.com, there is a link to a site that will completely answer any question about the compact bulb causing eye disease and blindness in many species of reptile.