Filing in this dataset of 456 records is concentrated among a small number of established ophthalmic-lens and photochromic-dye suppliers, with the leading assignee holding 118 records against 28 at fifth place. The top 5 assignees combined hold 290 records, or 63.6% of the total, and the top 10 extend that to 373 records, or 81.8%. Below that ranked group of 82 companies, filing activity thins out quickly into single- and few-filing entrants, so most of the enforceable claim density sits with a handful of long-standing players.

Annual filings peaked at 26 in 2017 and had fallen to 6 by 2024, a 60% drop from the 2021 level of 15. This does not necessarily mean the technology is losing commercial relevance; dense early filing on core darkening-kinetics and matrix-compatibility claims can itself discourage further filing in the same claim space. It is also worth noting that 2025 and 2026 figures in any such dataset are understated because publication typically lags filing by around 18 months, so the most recent apparent decline should be read cautiously.

In this dataset, both fall under a shared search combining photochromic dye and tinted lens terms with process and performance criteria like darkening kinetics, fade-back time and imbibition processing. Photochromic claims typically centre on dye chemistry (heterocyclic compounds under C07D, materials under C09K) and how that dye interacts with a polymer matrix, while tinted-lens claims lean more on polymer composition and additive classes such as C08K and C08L. The two overlap heavily in practice because photochromic dyes are usually imbibed or compounded into the same lens substrate materials used for static tints.

US10197236B2, assigned to Ford Global Technologies, claims a vehicle headlamp system that uses a photochromic lens combined with a secondary UV light source, a heating system, an obstacle sensor and a controller that actively darkens or lightens the lens in response to sensor data. Its claims are specific to an automotive headlamp assembly with sensor-driven control, not to spectacle or ophthalmic lens materials generally. A photochromic spectacle lens developer would not typically infringe this patent unless building a sensor-controlled, actively heated automotive lighting system using a similar architecture.

The technology composition shows heavy density in core optical (G02B, 59.0% of records) and spectacle (G02C, 40.8%) classes, alongside dye and polymer chemistry classes like C09K, C07D, C08K, C08F and C08L. Lower-density branches — blue-light-filtering dye blends, low-temperature fade-back kinetics, and sensor-linked automotive glazing applications — carry comparatively lighter claim coverage relative to the core chemistry. These are the areas where a first claim is less likely to run straight into the dense prior art held by the top-ranked assignees.