Abstract. Degeneration of retinal pigment epithelial ͑RPE͒ cells severely impairs the visual function of retina photoreceptors. However, little is known about the events that trigger the death of RPE cells at the subcellular level. Twophoton excited autofluorescence ͑TPEF͒ imaging of RPE cells proves to be well suited to investigate both the morphological and the spectral characteristics of the human RPE cells. The dominant fluorophores of autofluorescence derive from lipofuscin ͑LF͒ granules that accumulate in the cytoplasm of the RPE cells with increasing age. Spectral TPEF imaging reveals the existence of abnormal LF granules with blue shifted autofluorescence in RPE cells of aging patients and brings new insights into the complicated composition of the LF granules. Based on a proposed twophoton laser scanning ophthalmoscope, TPEF imaging of the living retina may be valuable for diagnostic and pathological studies of age related eye diseases. Aged-related macular degeneration ͑AMD͒ is the principal cause of irreversible loss of vision and registered legal blindness for aging people in developed countries. To place this in perspective, 35% of the human population over the age of 75 has some degree of AMD.

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A wide variety of nanoparticles are playing an increasingly important role in drug delivery. Label‐free imaging techniques are especially desirable to follow the cellular uptake and intracellular fate of nanoparticles. The combined correlative use of different techniques, each with unique advantages, facilitates more detailed investigation about such interactions. The synergistic use of correlative coherent anti‐Stokes Raman scattering and electron microscopy (C‐CARS‐EM) imaging offers label‐free, chemically‐specific, and (sub)‐nanometer spatial resolution for studying nanoparticle uptake into cells as demonstrated in the current study. Coherent anti‐Stokes Raman scattering (CARS) microscopy offers chemically‐specific (sub)micron spatial resolution imaging without fluorescent labels while transmission electron microscopy (TEM) offers (sub)‐nanometer scale spatial resolution and thus visualization of precise nanoparticle localization at the sub‐cellular level. This proof‐of‐concept imaging platform with unlabeled drug nanocrystals and macrophage cells revealed good colocalization between the CARS signal and electron dense nanocrystals in TEM images. The correlative TEM images revealed subcellular localization of nanocrystals inside membrane bound vesicles, showing multivesicular body (MVB)−like morphology typical for late endosomes (LEs), endolysosomes, and phagolysosomes. C‐CARS‐EM imaging has much potential to study the interactions between a wide range of nanoparticles and cells with high precision and confidence.

We built a device sensitive to the birefringence of the retinal nerve fiber layer for biometric purposes. A circle of 20 degrees diameter on the retina was scanned around the optic disk with a spot of light from a 785 nm laser diode. The nonbirefringent blood vessels indenting or displacing the retinal nerve fiber layer were seen as "blips" in the measured birefringence-derived signal. For comparison, the reflection-absorption signature of the blood vessel pattern in the scanned circle was also measured. The birefringence-derived signal proved to add useful information to the reflectance-absorption signature for retinal biometric scanning.