Related Clues:

• It's behind pupil starting off learning each new subject
• Leonard's telescope will have one
• Smartphone part
• City in northern France producing optical equipment
• Industrial town in Pas de Calais department
• Vitreous humor's neighbor
• Eye contact?
• Shooter's accessory
• It enables one to focus
• Viewpoint, metaphorically
• Bender of light
• Camera part wrapped in woollen socks
• Inclines to dismiss a visual aid
• Something you can see through
• Goggles part