Optical manipulation from the microscale to the nanoscale: fundamentals, advances and prospects.

Since the invention of optical tweezers, optical manipulation has advanced significantly in scientific areas such as atomic physics, optics and biological science. Especially in the past decade, numerous optical beams and nanoscale devices have been proposed to mechanically act on nanoparticles in increasingly precise, stable and flexible ways. Both the linear and angular momenta of light can be exploited to produce optical tractor beams, tweezers and optical torque from the microscale to the nanoscale. Research on optical forces helps to reveal the nature of light-matter interactions and to resolve the fundamental aspects, which require an appropriate description of momenta and the forces on objects in matter. In this review, starting from basic theories and computational approaches, we highlight the latest optical trapping configurations and their applications in bioscience, as well as recent advances down to the nanoscale. Finally, we discuss the future prospects of nanomanipulation, which has considerable potential applications in a variety of scientific fields and everyday life.

Laser photocoagulation versus combined laser photocoagulation and posterior sub-Tenon's triamcinolone injection for the primary treatment of diffuse diabetic macular edema.

PURPOSE: To evaluate the effectiveness of combined treatment with posterior sub-Tenon's triamcinolone injection and focal laser photocoagulation, compared with laser treatment alone, in diffuse diabetic macular edema. METHODS: This was a nonrandomized, prospective, controlled study that involved 20 eyes with diffuse diabetic macular edema. The patients were divided into 2 groups: group I (10 eyes) received focal laser photocoagulation alone; and group II (10 eyes) received combined focal laser photocoagulation and posterior sub-Tenon's triamcinolone injection. All patients were followed for 6 months. Main outcome measures were final visual outcome and fluorescein leakage and retreatment rates at the end of the follow-up period. RESULTS: Combined therapy showed better visual and angiographic outcome at 6 months. The retreatment rate was significantly lower in the combined-therapy group compared with the laser-therapy-alone group, with more stable visual acuity. CONCLUSION: Improvement of visual acuity and decreased fluorescein leakage suggest that combination therapy with posterior sub-Tenon's triamcinolone injection and focal laser photocoagulation, particularly when used as a first-line therapy, is advantageous and merits further investigation.