Is this what you see when a coworker comes to your desk?
I have a solution for you - turn on the light!
I like a bright workspace. It energizes me and keeps me motivated. Dim light makes me tired and sleepy. I prefer to have a desk that's right by a window so I can look out at the world from time to time. My desk is near a window, although not right next to one; however, not all of you will be even that fortunate and for that you have my condolences.
If you're located in an area where there isn't much natural light and the room lights aren't in the best position relative to your desk, you may want to consider adding a lamp. Or maybe it's your reception area that needs better lighting. Or the lab. A lamp is an easy addition and very often a forgotten element. If you don't have a lot of empty space on your desktop (all those sorters, card files and tape dispensers take up a lot of room), consider a clamp-on style. They can provide just what you need without taking up valuable space.
What is the style of your office?
Is it traditional?
(Is it just me or does that last one look like a giraffe?)
Good lighting is also essential for your health. When you read articles about ergonomics, you see advice about chair height, keyboard and monitor positions, etc., but those articles don't normally mention light. We all know that reading in dim light isn't good for us, so don't neglect that aspect of your workspace. Be sure to have a well-lit work area.
And don't forget the light bulbs!