Lifetime Standard for Fluorescence Lifetime Imaging Ophthalmoscopy.

PURPOSE: The goal of this effort was to develop a simple, reliable, flexible, and readily transferable fluorescence lifetime standard (as a phantom eye) for use in fluorescence lifetime imaging ophthalmoscopes (FLIOs).

METHODS

We manufactured by 3D-printing a "fundus piece" designed to fit in a commercially available phantom eye that simulates the optics of the eye. The fundus piece contains a chamber subtending the retina which is filled with a liquid solution of a fluorophore already established in the field as a lifetime standard, which can then be imaged in the FLIO.

RESULTS

After several trials of design and 3D-printing resins, a design of the fundus piece in a photopolymerizable resin was found which gave low fluorescence background. Similar results (within 5% of the pre-exponential factor-weighted average lifetime in a two-component fit) were obtained in three different FLIOs with two different excitation lasers and two standard fluorophores, in comparison to published values.

CONCLUSIONS

We conclude that this approach offers a relatively straightforward and flexible means to standardize FLIO instruments.

TRANSLATIONAL RELEVANCE: Our approach is relevant to clinical translation of FLIO for three reasons: first, it offers the operator a subject-free means to verify that instrument performance is within specifications; second, it can be used to troubleshoot causes of performance shortfalls; and, third, it makes feasible multicenter trials and intercomparison of data obtained with different instruments.