Characteristics of laterality in the optic nerve head microcirculation obtained by laser speckle flowgraphy in healthy subjects.

PURPOSE: To determine the characteristics of the laterality of the ocular microcirculation parameters obtained from laser speckle flowgraphy (LSFG) in the optic nerve head (ONH). SUBJECTS AND METHODS: We reanalyzed a total of 240 healthy subjects (169 men, 71 women) who had participated in a medical checkup program. We analyzed the average mean blur rate (MBR), maximum MBR (Max-MBR), minimum MBR (Min-MBR), and area ratio of the blood stream (ARBS). As the pulse waveform parameters, we also calculated the skew, blowout score (BOS), blowout time (BOT), rising rate, falling rate, flow acceleration index (FAI), acceleration time index (ATI), resistivity index (RI), and beat strength over MBR (BOM). All parameters were compared between left and right eyes. RESULTS: MBR-average, MBR-Max, MBR-Min, ARBS, skew, BOT, rising rate, falling rate, FAI, ATI, and ARBS did not differ significantly between the right and left eyes. The BOS in the right eyes was significantly lower than that of the left eyes, and the RI and BS in the right eyes were significantly higher than those of the left eyes. Similarly, for the whole of the ONH, the BOS in the tissue area (Tissue) and in the vessel area (Vessel) of the right eyes were significantly lower than those of the left eyes, and RI-Tissue, RI-Vessel, BOM-Tissue, and BOM-Vessel in the right eyes were significantly higher than those of the left eyes. CONCLUSION: By using LSFG, we observed laterality of the BOS, RI, and BOM, all of which are pulse wave form parameters in the ONH.

Decrease in choroidal blood flow after half and one-third dose verteporfin photodynamic therapy for chronic central serous chorioretinopathy.

BACKGROUND: The effect of various reduced doses of verteporfin photodynamic therapy (PDT) on choroidal blood flow in chronic central serous chorioretinopathy (CSC) remains unclear. Therefore, this study aimed to evaluate choroidal blood flow after half-dose PDT (1/2PDT) and one-third dose PDT (1/3PDT) with verteporfin for chronic CSC using laser speckle flowgraphy and spectral-domain optical coherence tomography. METHODS: Twenty-seven eyes of 27 patients with serous retinal detachment (SRD) caused by chronic CSC for more than 6 months were included in this study. Patients were divided into the 1/2PDT (n = 12; January 2018 to July 2019) and 1/3PDT (n = 15; August 2016 to December 2017) groups based on the treatment period. The best-corrected visual acuity (BCVA), central retinal thickness (CRT), central choroidal thickness (CCT), and mean blur rate in the macular area (m-MBR) and optic nerve head (ONH-MBR) were obtained using laser speckle flowgraphy and evaluated at baseline (pre-treatment), and 2 weeks, 1 month, 3 months, and 6 months after treatment. RESULTS: We found that SRD disappeared after 1 month in 92 and 93% of patients' eyes in the 1/2PDT and 1/3PDT groups, respectively. Recurrence of SRD was observed in one eye at the 6-month follow-up after 1/2PDT and two eyes at the 3-month follow-up after 1/3PDT. No significant improvement was observed in baseline BCVA in the 1/3PDT and 1/2PDT groups. The average m-MBR against baseline significantly decreased at 2 weeks and 1, 3, and 6 months in the 1/2PDT group. The average m-MBR against baseline decreased significantly only at the 2 weeks follow-up in the 1/3PDT group. The average rate of change in the CCT against baseline decreased significantly throughout for up to 6 months in the 1/2PDT group and for up to 3 months in the 1/3PDT group. No significant fluctuation was observed in the ONH-MBR. CONCLUSIONS: Here, PDT significantly affected choroidal blood flow depending on the verteporfin dose in chronic CSC. TRIAL REGISTRATION: This trial was retrospectively registered ( UMIN000026850 ; Approval date 03/04/2017).

Novel superpixel method to visualize fundus blood flow resistivity in healthy adults.

We aimed to perform superpixel segmentation of ocular blood flow maps obtained using laser speckle flowgraphy (LSFG) and investigate the effects of systemic parameters such as body weight, height, and sex on ocular blood flow resistivity. We studied 757 healthy participants (583 men, 174 women). We calculated the average beat strength over mean blur rate (BOM) as a LSFG resistivity index, as a function of age and sex using ordinary regions of interest (ROI) centered on the optic nerve head (ONH), the retinal vessels region and tissue around the ONH, and the choroid (CHD). We compared the ROI and superpixel-based methods, which are segmented based on image processing, for calculating the BOM. The sex differences in the BOM for the ONH, retinal-vessels region and tissue region of the ONH and CHD were significant for individuals aged ≤ 50 years (P < 0.01) but not those > 50 years old (P > 0.05). The average BOMs calculated using the ROI and superpixel methods were strongly correlated in the ONH (coefficient = 0.87, R2 = 0.8, P < 0.0001, n = 5465). In summary, a superpixel-segmented BOM map is suitable for two-dimensional visualization of ocular blood flow resistivity.

Effects of aging and exercise habits on blood flow profile of the ocular circulation.

PURPOSE: We examined the effects of aging and exercise habits on the ocular blood flow (OBF) and its profiles throughout the optic nerve head region and choroidal area. We hypothesized that exercise habits reduce the stiffness of vessels in the ocular circulation, which generally increases with aging. METHODS: Participants in a medical checkup program (698 males and 192 females aged 28 to 80 years) were categorized into 2 groups (with and without exercise habits) based on participant self-reporting and the definition of the Ministry of Health, Labor and Welfare of Japan (MHLW). OBF in the right eye was measured and analyzed using laser speckle flowgraphy. The blowout time (BOT), which is the time during which the blood flow is higher than half of the mean of the minimum and maximum signals during one heartbeat, was calculated as an index of the blood flow profile. BOT has been used as an indicator of the flexibility of blood vessels. RESULTS: BOT significantly decreased with aging. Neither the self-reported nor MHLW-based exercise habits significantly affected the ocular circulation. CONCLUSION: These results indicate that the stiffness of the ocular vessels increases with aging, and this cannot be prevented by exercise habits.

Comparison of Two Preparation Methods for Platelet-Rich Plasma Eye Drops for Release of Growth Factors and De-Epithelization Rabbit Model.

Purpose: To compare two platelet-rich plasma (PRP) preparation methods (double spin (D-PRP) and TriCell PRP (T-PRP)) for eye drops, concentration yields of platelets and other cells, release of growth factors, and efficacy of the de-epithelization rabbit model. Methods: PRP was extracted by D-PRP and T-PRP from 30 ml blood from healthy adults. After extraction, platelets and leukocytes were counted. D-PRP and T-PRP were preserved during A: 1 h storage at room temperature, B: 1 h storage at -20°C, C: 24 h storage at 4°C, and D: 24 h storage at -20°C. Platelet-derived growth factor (PDGF) was measured. Freezing/thawing PRP eye drops and control were instilled in the de-epithelization rabbit model four times per day for 5 days. Histology was compared between eyes treated with control, D-PRP, and T-PRP. Results: 14 ml of D-PRP and 4 ml of T-PRP were extracted from 30 ml whole blood samples. D-PRP and T-PRP had 41.36 ± 8.43 × 104 and 67.02 ± 13.55 × 104 platelets and 0.41 ± 0.24 × 103/ml and 10.09 ± 4.29 × 103/ml leucocytes, respectively. In the four storage methods, PDGF concentrations in T-PRP were higher than those in D-PRP eye drops. Freezing/thawing D-PRP and T-PRP increased PDGF concentrations. Histology showed corneal epithelium thickness in T-PRP-treated eyes after healing (38.41 ± 9.10 µm) was significantly higher than that in control-treated (27.77 ± 4.76 µm) and D-PRP-treated eyes (18.32 ± 3.14 µm) (P < 0.05). There was no corneal damage with inflammation in corneal stroma and epithelium of all tested groups. Electron microscopy revealed strong adhesion between cell junctions in T-PRP-treated eyes. Conclusions: Freezing/thawing of PRP extracted with the T-PRP kit may result in high platelet and leukocyte concentration and produce high PDGF concentration. PRP eye drops including leucocytes could increase thickness of corneal epithelium without corneal inflammation.

Correlation between Blood Flow and Temperature of the Ocular Anterior Segment in Normal Subjects.

PURPOSE: To determine a correlation between temperature and blood flow in the ocular anterior segment, and their effects on corneal temperature. METHODS: In experiment 1, we recruited 40 eyes and measured the temperature and blood flow in the ocular anterior-segment (upper/lower eyelid skin, palpebral and bulbar conjunctiva, and cornea) before and after application of warm compresses. In experiment 2, we recruited 20 eyes and measured the same tissues before and during stimulation using water and capsaicin solution in the oral cavity. RESULTS: In experiment 1, the temperatures of the upper/lower eyelid skin and cornea increased significantly until 15 min after the application of the warm compress; the temperatures of the palpebral and bulbar conjunctiva increased significantly until 10 min. The blood flow in the upper/lower eyelid skin and bulbar conjunctiva increased significantly until 10 min, and that of the palpebral conjunctiva increased significantly until 15 min. In experiment 2, the temperatures were correlated significantly with the blood flow in the upper and lower eyelid skin and palpebral and bulbar conjunctiva. The temperature of all locations and palpebral conjunctival blood flow contributed independently to the corneal temperature. CONCLUSIONS: In the ocular anterior segment, the temperature and blood flow were correlated significantly, and contributed to the corneal temperature.

The influences of gender and aging on optic nerve head microcirculation in healthy adults.

Potential differences in the nature of the influences of aging and gender on the optic nerve head (ONH) microcirculation, using laser speckle flowgraphy (LSFG) were evaluated. We studied 908 healthy subjects (men = 701, age: 50.0 ± 9.1 yrs, women = 208, 49.8 ± 9.5 yrs, p = 0.76). The average, maximum (Max), and minimum (Min) mean blur rate (MBR) in a heartbeat were evaluated. The parameters were analyzed separately for the tissue, vessels, and throughout the ONH (All). We investigated which MBR sections are correlated with gender and age by univariate and multivariate regression analyses. The Max MBR-All (r = -0.31) was most strongly correlated with gender (men = 1, women = 0). The Min MBR-All (r = -0.24) was most strongly correlated with age, followed by Min MBR-All (r = -0.20). The factors contributing independently to the Max MBR-All were gender (ß = -0.15), pulse pressure, spherical refraction, ocular perfusion pressure, and red blood cell (RBC) count. The factors contributing independently to the Min MBR-Vessel were gender (ß = -0.09), age (ß = -0.25), body mass index, heart rate, and spherical refraction. The factors contributing independently to the Min-MBR-All were age (ß = -0.22), heart rate, and RBC count. Our results revealed that gender differences influence the Max MBR, and aging influences the Min MBR. These correlations were stronger than that of average MBR.

Association among Blink Rate, Changes in Ocular Surface Temperature, Tear Film Stability, and Functional Visual Acuity in Patients after Cataract Surgery.

PURPOSE: To investigate the association among the ocular surface temperature (OST), tear film stability, functional visual acuity (FVA), and blink rate in patients after cataract surgery. METHODS: We recruited 98 eyes of 69 patients (mean age, 73.7 ± 5.2 years) 1 month after phacoemulsification with implantation of acrylic intraocular lenses and assessed slit-lamp microscopy, corrected distance VA, FVA, noninvasive tear breakup time (NIBUT), and OST. We defined the changes in the OST from 0 to 10 seconds after eye opening as the ΔOST. We measured the FVA and blink rate using the FVA measurement system. We divided the patients into two groups based on tear film stability: stable tear film (NIBUT, >5.0 seconds) and unstable tear film (NIBUT, ≤5.0 seconds). We evaluated the differences between the two groups and the association between the blink rate and other clinical parameters. RESULTS: The unstable tear film group (56 eyes) had significantly (p < 0.0001, unpaired t-test) shorter NIBUTs than the stable tear film group (42 eyes). The ΔOSTs and blink rates were significantly (p < 0.0001) higher in the unstable tear film group than in the stable group. Linear single regression analysis showed that the ΔOST (r = -0.430, p < 0.0001), NIBUT (r = -0.392, p < 0.0001), and gender (r = -0.370, p=0.0002) were correlated significantly with the blink rate. Multiple regression analysis showed that the ΔOST independently contributed to the blink rate. CONCLUSIONS: The frequency of blinks is associated with tear film stability in patients after cataract surgery. The blink rate may be useful for evaluating the tear film stability in clinical practice. The ΔOST should be an important contributing factor to the blink rate. [This trial is registered with UMIN000026970].

Influence of age and gender on the pulse waveform in optic nerve head circulation in healthy men and women.

The influences of age and gender differences on the pulse waveform in the optic nerve head (ONH) in healthy adults, using laser speckle flowgraphy (LSFG) were evaluated. We studied 908 healthy subjects (men = 701, age: 50.0 ± 9.1, women = 208, age: 49.8 ± 9.5, p = 0.76), evaluating these pulse waveform parameters: the blowout score (BOS), blowout time (BOT), acceleration time index (ATI), and the rising and falling rates. The parameters were analyzed separately for the tissue, vessels, and throughout the optic nerve head (All). All parameters were compared between genders. We investigated which independent factors for the pulse waveform in the ONH is most strongly correlated with age. All sections of the BOS, BOT, ATI, and falling rate showed a significant gender difference. A univariate regression analysis revealed that BOT-Tissue showed the strongest correlation with age (r = -0.51). The factors contributing independently to the BOT-Tissue were gender, age, heart rate, mean arterial blood pressure, pulse pressure, spherical refraction, and estimated glomerular filtration rate. Among the subjects aged >41 years, the chronological changes of BOT-Tissue in the women were significantly lower than those in the men. We concluded that the pulse waveform in the ONH has clear differences between the genders and shows chronological changes.