MDCG 2025-7: Master UDI-DI implementation timelines, explained

Who this applies to

This position paper applies to manufacturers of highly individualised optical devices: contact lenses, spectacle frames, spectacle lenses and ready-to-wear reading spectacles. It is also relevant to importers, distributors, UDI issuing entities and teams preparing device data for Eudamed.

The problem it solves is timing. These products already have UDI labelling and Eudamed registration obligations, but the Master UDI-DI solution designed to group highly individualised variants becomes mandatory later. MDCG 2025-7 explains what happens in the gaps.

The dates that matter

Contact lenses produced before 9 November 2026 do not need a Master UDI-DI on the label. Spectacle products produced before 1 November 2028 receive the equivalent treatment.

The difficult periods are therefore 28 May–8 November 2026 for contact lenses and 28 May 2026–31 October 2028 for spectacles: the Eudamed module is mandatory, but the relevant Master UDI-DI assignment rule is not yet mandatory.

Voluntary early assignment is the intended bridge

The delegated regulations allow manufacturers to assign a Master UDI-DI before the mandatory application dates. MDCG 2025-7 strongly encourages this once the relevant issuing-entity standard and Eudamed functionality are available.

That choice has consequences. Once a manufacturer voluntarily assigns a Master UDI-DI, the paper says the obligation to label it and register the device in Eudamed follows immediately. “Voluntary” describes the decision to enter the Master UDI-DI system early; it does not mean the manufacturer can assign the identifier but postpone the connected label and registration work.

Until the solution is available, highly individualised products continue to use an issuing-entity identifier or similar internal manufacturer device identifier under the current procedure. Manufacturers therefore need a controlled migration rather than an overnight identifier swap.

Labelling, registration and vigilance are connected but separate

Master UDI-DI acts as the UDI-DI for the defined group of highly individualised devices. It reduces the number of identifiers that would otherwise be needed for large prescription and design ranges.

Do not collapse three implementation questions into one:

1. Assignment: when the issuing entity creates the Master UDI-DI under its standard.
2. Labelling: when the identifier must appear in the UDI carrier on the device label and relevant packaging.
3. Registration and reporting: when the Master UDI-DI and device dataset are entered in Eudamed and used in vigilance reporting.

Once Eudamed's Vigilance and Post-Market Surveillance module becomes mandatory, the Master UDI-DI should be used for vigilance cases where it has already been assigned, even if the final mandatory assignment date for that product group has not arrived.

What changed in Rev.1

The December 2025 revision adds the two delegated regulations governing contact-lens and spectacle Master UDI-DI, replaces the provisional Eudamed reference with the confirmed 28 May 2026 mandatory date, updates the spectacle application date and timeline diagram, and adds the current references for the Eudamed vigilance/PMS module and the detailed spectacle guidance in MDCG 2025-8.

What this means for you, practically

1. Build one product-level transition inventory. For every contact lens or spectacle range, record class, existing identifier, Basic UDI-DI, issuing entity, label version, Eudamed record and target Master UDI-DI date.
2. Choose your voluntary-assignment date deliberately. Align issuing-entity readiness, Eudamed functionality, packaging depletion and data validation; do not assign early without capacity to label and register.
3. Design the mapping before migration. Preserve the relationship between old identifiers, catalogue references, Basic UDI-DIs, Master UDI-DIs and UDI-PIs so complaints and incidents remain traceable across the transition.
4. Separate production date from market activity. The labelling relief is tied to products produced before the applicable date. Your records need to prove which label rule applied to each batch.
5. Update vigilance procedures. Make sure the complaint and incident workflow can identify the affected variant inside a grouped Master UDI-DI and can report the available identifier through the correct Eudamed route.