Why won't my transition lenses go clear?

Transition lenses, also known as photochromic lenses, may not go completely clear due to a combination of factors, primarily involving environmental conditions like temperature, the presence (or absence) of ultraviolet (UV) light, and the age of the lenses.

Key Reasons Your Transition Lenses Aren't Clearing Up

Several factors can influence the ability of your photochromic lenses to return to their clear state. Understanding these can help you diagnose why your lenses might be retaining a slight tint.

1. Temperature Influence

Temperature plays a significant role in how photochromic lenses function. The speed at which these lenses change color, both darkening and clearing, is directly influenced by the ambient temperature:

• Colder Climates: In colder environments, transition lenses tend to take longer to clear out completely. The chemical reaction that causes them to lighten slows down when temperatures drop, meaning they might retain a slight tint for a longer period after you've moved indoors or out of direct sunlight.
• Hotter Climates: While less directly related to not clearing, it's worth noting that in extremely hot weather, the lenses might not reach their darkest possible shade. This illustrates how temperature generally affects their performance across the board.

2. Lack of UV Exposure (for Darkening) or Inconsistent UV Exposure (for Clearing)

Transition lenses primarily react to ultraviolet (UV) light. When you move indoors, away from UV, they should begin to clear. However, certain situations can hinder this:

• Inside a Car: Car windshields typically block most UV rays. This means your transition lenses won't darken significantly while you're driving, and similarly, if they have a slight tint from previous UV exposure, they might not clear fully inside the car due to the lack of the specific light spectrum that triggers their clearing mechanism at optimal speed.
• Minimal UV in Artificial Light: Most indoor artificial light sources (like LED, fluorescent, or incandescent bulbs) emit very little to no UV light. This absence of UV allows the lenses to clear, but they won't react to subtle indoor light changes.

3. Lens Age and Wear

Like many optical products, transition lenses have a lifespan. Over time, their photochromic properties can degrade:

• Reduced Responsiveness: After several years of use (typically 2-3 years, but varies by lens), the chemical compounds responsible for the darkening and clearing reactions can become less efficient. This can result in lenses that don't darken as much in the sun and, critically, don't clear as completely indoors, retaining a persistent yellowish or grayish tint.
• Uneven Tinting: You might notice that different parts of the lens clear at different rates or that one lens remains darker than the other.

4. Residual UV or Indoor Lighting Conditions

Even indoors, subtle factors can prevent complete clarity:

• Proximity to Windows: If you spend a lot of time near windows, especially south-facing ones, some UV light can still penetrate, preventing your lenses from becoming perfectly clear.
• Specific Lighting Types: Certain specialized indoor lighting, such as grow lights or some older fluorescent tubes, might emit a small amount of UV that can keep your lenses slightly tinted.

5. Lens Technology and Type

Not all photochromic lenses are the same. Different brands, generations, and types of transition lenses offer varying performance characteristics:

• Older Generations: Older versions of photochromic technology might inherently clear slower or less completely than the latest advancements.
• Specific Lens Designs: Some specialized photochromic lenses might be designed for specific uses (e.g., extra dark for intense sunlight) and might have slightly different clearing profiles.

Solutions and Tips for Clearer Lenses

If your transition lenses aren't clearing as expected, consider these steps:

• Be Patient: Especially in colder weather, give your lenses more time to clear once you're indoors.
• Clean Your Lenses Regularly: Dirt, smudges, and oils can affect the clarity and perceived tint of your lenses. Use a microfiber cloth and appropriate lens cleaner.
• Store Lenses Properly: When not in use, keep your glasses in a case to protect them from environmental factors and extend their life.
• Consider Lens Replacement: If your lenses are several years old and showing signs of degradation, it's likely time for a new pair. Consult your eye care professional.
• Consult Your Eye Care Professional: If you're concerned about the performance of your lenses or if they are relatively new and not functioning correctly, your optician can assess them and offer specific advice or solutions.

Understanding Transition Lens Behavior

Here's a quick overview of how common conditions affect transition lens performance: