Coalescence and mixing dynamics of droplets in acoustic levitation by selective colour imaging and measurement.

Acoustic levitation is well-suited to 'lab-on-a-drop' contactless chemical analysis of droplets. Rapid mixing is of fundamental importance in lab-on-a-drop platforms and many other applications involving droplet manipulation. Small droplets, however, have low Reynolds numbers; thus, mixing via turbulence is not possible. Inducing surface oscillation is effective in this regard, however, the relationship between internal flow and mixing dynamics of droplets remains unclear. In this study, we conducted a set of simultaneous optical measurements to assess both the flow field and the distribution of fluid components within acoustically levitated droplets. To achieve this, we developed a technique to selectively separate fluorescent particles within each fluid, permitting the measurement of the concentration field based on the data from the discrete particle distribution. This approach revealed a relationship between the mixing process and the internal flow caused by surface oscillation. Thus, the internal flow induced by surface oscillation could enhance droplet mixing. Our findings will be conducive to the application and further development of lab-on-a-drop devices.

Foveal and Macular Thickness in a Japanese Population: The Hisayama Study.

PURPOSE: To examine factors associated with foveal thickness (FT) and macular thickness (MT) in Japanese persons from Hisayama. METHODS: A total of 2216 healthy eyes of 1384 participants were analyzed. Each participant underwent comprehensive physical and ophthalmic examinations, the latter including optical coherence tomography (OCT). Multiple regression analysis was used to determine the relationship of various factors (race, age, sex, refractive error, axial length, diabetes mellitus, fasting plasma glucose levels, alcohol intake and smoking status) to FT (central 1-mm foveal area) and MT (central 3-mm foveal region). RESULTS: Results of multiple linear regression analysis indicated that age was positively associated with FT (ß coefficient 0.214 µm). FT was significantly smaller in women than men (ß coefficient -9.146 µm). For both sexes, body height was positively correlated (ß coefficient 0.257 µm), while refractive error and current smoking were negatively associated (ß coefficients -1910 µm and -4.410 µm, respectively) with FT. With respect to MT, there were negative associations between age, sex (female), and refractive error (ß coefficients -0.268 µm, -4.815 µm and -0.699 µm, respectively). For both sexes, body height was positively correlated (ß coefficient 0.227 µm), while hypertension and current smoking were negatively associated (ß coefficients -1.999 µm and -2.758 µm, respectively) with MT. CONCLUSIONS: Our results indicated that age, body height, refractive error, and current smoking were significantly associated with FT, whereas age, body height, refractive error, current smoking, and hypertension were significantly related to MT. Women had significantly smaller FT and MT than men.

Relationship between aqueous flare and visual function in retinitis pigmentosa.

PURPOSE: To investigate the correlation between aqueous flare values and central visual function in patients with retinitis pigmentosa (RP). DESIGN: Retrospective, observational case series. METHODS: We retrospectively studied 160 patients diagnosed with typical RP and 59 control subjects. Aqueous flare values were measured by laser flare cell meter. The relationships between aqueous flare and best-corrected visual acuity (VA) and mean deviation (MD) of static perimetry tests were analyzed in RP patients. RESULTS: The aqueous flare values were significantly higher in the RP patients compared to the control subjects (10.6 ± 7.9 vs 5.0 ± 2.1 photon counts per millisecond [pc/ms], P < .0001). In the RP patients, the aqueous flare values were negatively correlated with VA (r = 0.359, P < .0001) and MD (r = -0.330, P < .0001). Age-subgroup analysis showed a significant correlation between aqueous flare and VA in the RP patients' 40s, 50s, and 60s and between aqueous flare and MD in the 30s, 40s, 50s, and 60s. The RP patients with MD values ≥-15 decibels (dB) showed significantly higher levels of aqueous flare than those with MD values <-15 dB (12.0 ± 6.2 vs 8.7 ± 5.8, P = .0001). CONCLUSIONS: Aqueous flare is increased in RP patients and negatively correlates with central visual function. These results suggest a close relationship between inflammation and central vision loss in RP.

Correlation between macular blood flow and central visual sensitivity in retinitis pigmentosa.

PURPOSE: To investigate the changes in macular blood flow and the correlation between those changes and central visual function in patients with retinitis pigmentosa (RP). METHODS: The mean blur rate (MBR), a quantitative blurring index of the laser speckle pattern that represents retinal and choroidal blood flow, was measured by laser speckle flowgraphy. Mean blur rate values in the macular area were compared between 70 patients with RP and 28 control subjects. The relationships between MBR on the one hand and, on the other, visual acuity (VA), mean deviation (MD) and averaged macular sensitivity of static perimetry tests (Humphrey Filed Analyzer, the central 10-2 program) were analysed in patients with RP. RESULTS: Macular MBR was decreased to 75% in patients with RP compared with control subjects (p < 0.0001, Student's t-test). Spearman's rank testing showed that macular MBR was significantly correlated with VA (r = -0.261, p = 0.0299), MD values (r = 0.438, p = 0.0002) and averaged macular sensitivity at the central 4 and 12 points of static perimetry tests (r = 0.426 and 0.442, p = 0.0003 and 0.0002, respectively). Multivariable-adjusted analysis confirmed that MBR was independently associated with MD (p = 0.0002) and macular sensitivity at the central 4 and 12 points (p < 0.0001 and 0.0002, respectively). CONCLUSIONS: Decreased macular blood flow was associated with reduced macular visual sensitivity in patients with RP. Although the cause-effect relationships remain to be elucidated, these findings suggest that vascular defects may be involved in the pathogenesis of RP such as central vision loss.

Factors affecting visual acuity after cataract surgery in patients with retinitis pigmentosa.

PURPOSE: To investigate the factors affecting visual acuity after cataract surgery in patients with retinitis pigmentosa (RP). DESIGN: Retrospective, observational study. PARTICIPANTS: We retrospectively reviewed the charts of a consecutive series of 40 patients with RP who underwent cataract surgery. METHODS: The changes in preoperative and postoperative best-corrected visual acuity (BCVA) were measured. We investigated the relation between preoperative mean deviation (MD) value on the Humphrey Field Analyzer (HFA: the central 10-2 program; Humphrey Instruments, Inc, San Leandro, CA) and final BCVA. We also investigated the relationship between preoperative ellipsoid zone (EZ; also called the inner/outer segment junction) conditions and final BCVA. In addition, we showed the prevalence of macular complications and capsule complications. MAIN OUTCOME MEASURES: The BCVA, slit-lamp biomicroscopic analysis, visual field, and optical coherence tomography (OCT) were obtained. RESULTS: The mean of the BCVA significantly improved after cataract surgery from 0.76 (range, -0.08 to 2.30) to 0.45 (range, -0.18 to 2.00) (P < 0.005). However, final BCVA did not improve in 30 eyes (53.6%). The preoperative MD value and the final BCVA were significantly correlated, and the final BCVA significantly improved in the less advanced RP group (MD was ≥-15 decibels [dB]). The final BCVA was significantly better in the group in which preoperative OCT showed a normal EZ than in the groups in which the EZ was abnormal or not visible. Posterior capsular opacification was observed in 47 eyes (83.9%), and 23 eyes (41.1%) underwent YAG laser capsulotomy within a mean follow-up time of 3 years. CONCLUSIONS: Final BCVA in approximately half of the eyes improved after cataract surgery in patients with RP. The preoperative ophthalmic examinations that may reflect macular (or foveal) function, such as HFA 10-2 program and OCT, are important parameters to assess postoperative visual outcome.