If your subject wears glasses and his face is tilted in a certain direction, a light source may cause a glare to show on his glasses. If you take a picture while this glare is present, it may show up in your photo. Glasses glare might also appear if the flash from your camera hits the glasses at a specific angle. Luckily, if you have iPhoto, you can remove the glare that appears on glasses in some photos.
Open iPhoto and the image you would like to retouch.
Click "Edit" on the toolbar to display Edit mode controls.
Select the "Retouch" option. The mouse cursor will turn into a crosshair.
Move your mouse to the area on the photo that is showing glasses glare. Click the right mouse button and drag the cursor over the glare spot to make a rectangle around the glare spot. Release the mouse to completely remove or almost remove the glasses glare.
Select "Adjust" within Edit mode if the glasses glare failed to completely disappear. You'll see options to adjust the brightness, contrast, sharpness, shadow and highlight levels.
Experiment with increasing and decreasing these controls until you no longer see the glare. The appropriate adjustment for each photo will be different, but begin by increasing the brightness of the photo.