Balance lenses are a bit of a tricky conversation in the industry; there is often some discrepancy on when they are prescribed, and how they are ordered. From a lab's perspective, a Balance lens is prescribed when a patient has no sight remaining in one eye, which signifies that the Optician may place any lens power in that side of the frame to cosmetically and functionally seek symmetry of the frame and facial features (making a mirror-image of the other eye's prescription often being the best default option). Historically, glass lenses made the weight aspect of this a priority, while modern (plastic) lenses weigh little enough to have much less impact. When a patient still uses that eye for navigating/balance/equilibrium however, the wearer's mobility can be compromised if the lens selected by the lab/dispensary acts in contradiction to good coordination (binocular vision) for the eye with limited vision. If you receive a prescription with 'BAL' prescribed, and would be uncomfortable with the possibility of effectively covering that eye while wearing glasses, it may be prudent to ask whether any specific lens strength in that eye would positively or negatively impact your coordination.

There is a possibility that the progressive/multifocal/office you are wearing is positioned too high or too low, or that the nosepads/general fit needs to be adjusted. That said, each part of these lenses is designed for a different viewing distance. It may be that the object you are trying to view is too close or too far, at the angle you are viewing it. If you can measure this exact distance, and the height of the object relative to you, it can provide critical information to your Optician, when they are troubleshooting this issue. It is possible that they may remake your lenses, but as this problem is very much a case-by-case issue, adjustment and viewing distance are typically considered first.

It's a good question, but requires a lot of information to process with any amount of meaningful accuracy. Lens thickness changes exponentially as you move away from the center, and frame size and shape will impact the final measurements significantly. Ideally, frame selection and lens design should seek to mitigate thickness at key areas where the lenses may otherwise rub (against your cheeks and eyebrows, typically) but mitigating overall thickness has meaningful impact on image size (and therefore blindspot size) and weight as well. If lens thickness and weight matter to you, you don't have to settle for a guess. Our shop has access to a program designed to calculate these figures, as do many others.

The threshold of impact resistance of polycarbonate is impressive, however it is not without its downsides. Polycarbonate is softer, and so scratches easily and is more likely to crack under continuous pressure. Its thermal properties cause a dramatically increased chance of the coatings crazing (rippling), and its light-transmitting properties are less optimized than standard plastic, resulting in what we call "chromatic aberration"; the splitting of a light source into its component colours, most noteably in higher prescriptions and at the edge of the lens. Further, if you are ordering a polycarbonate lens for a thin form profile, or non-safety rated frame, this largely undermines the point and purpose of its safety properties. A standard plastic lens will deflect the majority of real-world hazards, outside of a worksite, sporting event, or gun range, the vast majority of the time.

Most digital devices include a setting that can reduce blue light, rendering this lens coating limited in practicality. Presenting blue light as a new and uniquely harmful side effect of digital technology is discourtesy to patients, given any amount of time in natural sunlight will expose you to far more of it . Most blue light filters have the drawback of turning the world slightly yellow for the viewer. Additionally, blue light filters typically suffer from bright blue reflections off the lens surface, making it harder to see the wearer's eyes (or drive at night with those new LED headlights in your mirror). While lenses sold with blue light filters do include ultra violet protection, most are not compatible with photogrey technology, so light sensitivity outdoors can become a greater concern. All that said, if you're working for 8 hours a days at a screen and are looking for a computer-dedicated pair of glasses, then this might be the product for you.

Every lens material has its small benefits and drawbacks, but glass as a lens material hasn't aged well. Scratch resistant coatings on plastic lenses have improved to a level that renders glass as only a minor upgrade. Meanwhile, glass is almost twice the weight of standard lens plastic, which can lead to headaches, and sores on a wearer's nose or behind the ears. The few remaining glass-lens wearers we see have been wearing them for over a decade, but have not updated their prescription in that timeframe, which typically limits their vision. Add to this the risk of getting a shard of glass in your eye if they're hit by something, and most people are happy with a pair of plastic lenses that are more comfortable, safer, and have better options and availability.

Photochromic lenses (one popular brand name being "Transitions") are typically affected by two things: Light exposure (often U.V. light, specifically) and temperature. At sun-up and sun-down, light intensity is filtered through more of our atmosphere, and self-darkening lenses tend not to function at their maximum amount. Cloudy days, car interiors, and just being out of the direct sun can also impact this. To further complicate matters, hotter temperatures encourage photochromic lenses to return to clear, faster, while colder temperatures slow down the process, leaving them dark well after you've gone inside. Please avoid temperature-shocking your lenses by attempting to impact this, as it may ruin the coatings and void your warranty. Photochromic lenses work very well for reducing outdoor brightness with less cost or planning than a dedicated pair of sunglasses, and work well for most users, provided they understand these points and are making an informed purchase. We would advise against using photochromic lenses in areas of extreme heat; please consider some dedicated sunglasses.

While most brands of photochromic do take on a slight amount of colour over time (brown photochromics typically yellow more than grey), certain brands of photochromic are markedly better at retaining their clarity than others. If your lenses are within warranty, we would advise you to return to your place of purchase; they may replace them for you if the colouration is not subtle. Lab note: It is not impossible that an ordered set of good-quality photochromic lenses may be mistakenly substituted with an older or off-brand lens blank, accelerating this issue. Sadly, product testing for this is not something the industry has adequte tools for, but your place of purchase will likely correct the issue for you regardless. 

The yellow tone (and colour mismatch) in the image below is not normal, and should absolutely be remade if the lenses are within warranty.