Differences in optic nerve head microcirculation between evening and morning in patients with coronary artery disease

The Influence of Coronary Heart Disease on Retinal Electrophysiological Examination (Full-field, Pattern and Multifocal Electroretinograms)

PURPOSE

To evaluate the influence of coronary heart disease (CHD) on retinal function using a battery of electrophysiological measures.

MATERIALS AND METHODS

We conducted a prospective pilot study comparing 34 patients with a confirmed diagnosis of CHD with 21 healthy participants. Further inclusion criteria were a decimal visual acuity (VA) of 0.8 or better and patient age between 40 and 80 years. All participants were divided into three groups according to the severity of CHD (1, 2 or 3 vessels involved) and one healthy control group. Testing was performed on one eye per patient, either selecting the eye with higher VA or, when equal, selecting randomly. The test procedure consisted of a pattern electroretinogram (ERG), a full-field ERG, a multifocal ERG and an ophthalmic screening examination.

RESULTS

Implicit times of the b-wave measured using scotopic full-field ERG were significantly prolonged in all CHD patient groups (p < .000). Thus, full-field ERG allowed clinicians to differentiate between healthy patients and those suffering from CHD. The multifocal ERG showed significantly different results concerning the amplitude density (p < .008) in each patient group compared with the control group. CHD had a significant impact on cone-pathway function, although the severity of CHD did not correlate with functional deficiencies of cone cells.

CONCLUSIONS

Confirmed coronary vascular diseases are correlated with macular cone and bipolar cell function, which can be detected by measuring electrophysiological retinal signals.

Carotid endarterectomy restores decreased vision due to chronic ocular ischemia

BACKGROUND

The therapeutic effect of carotid endarterectomy (CEA) on visual disturbance caused by chronic ocular ischemia due to carotid artery stenosis has not been validated. This prospective observational study aims to investigate whether CEA is associated with an increase in ocular blood flow (OBF) and postoperative visual improvement.

METHODS

In total, 41 patients with carotid artery stenosis treated by CEA between March 2015 and September 2018 were enrolled in this study. OBF was evaluated by laser speckle flowgraphy, which can measure the mean blur ratio (MBR) which is well correlated to the absolute retinal blood flow. Visual acuity was assessed before and after CEA by subjective improvement and objective visual assessment using CSV-1000, an instrument used to test contrast sensitivity.

RESULTS

OBF increased after CEA on the operated side (mean MBR 33.5 vs 38.2, p < 0.001) but not on the non-operated side (mean MBR 37.8 vs 37.5, p = 0.50). After CEA, 23 patients (56.1%) reported subjective visual improvement on the operated side. The mean CSV-1000 score among the patients with increased OBF after CEA (5.44 vs 5.88, p = 0.04) but not among those without increased OBF (5.48 vs 5.95, p = 0.09). The mean CSV-1000 scores increased significantly after CEA in 18 patients with decreased vision and decreased OBF (4.51 vs 5.37, p < 0.001), but not in the 23 patients without those (6.19 vs 6.31, p = 0.6).

CONCLUSION

CEA may successfully reverse visual dysfunction caused by chronic ocular ischemia due to carotid artery stenosis by increasing OBF.

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 (β = −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 (β = −0.09), age (β = −0.25), body mass index, heart rate, and spherical refraction. The factors contributing independently to the Min-MBR-All were age (β = −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.

Assessment of ocular microcirculation in patients with end-stage kidney disease

PURPOSE

To determine the impact that end-stage kidney disease (ESKD) has on ocular microcirculation in the optic nerve head (ONH) and choroid area shown by laser speckle flowgraphy (LSFG).

METHODS

We studied 24 consecutive Japanese patients with ESKD who visited the department of Nephrology at our hospital and 55 age- and gender-matched subjects who had undergone polysomnography. The mean blur rates (MBRs) in vessels (MBR-Vessel), in the tissue (MBR-Tissue), throughout the ONH (MBR-All), and throughout the choroid (MBR-Choroid) were analyzed. We divided the MBR-Tissue into four sections (superior, temporal, inferior, and nasal). The results of systemic and ocular parameters were compared between the ESKD patients and control subjects. We performed single and multiple regression analyses to determine the MBR section(s) that correlated most strongly with serum creatinine and the estimated glomerular filtration rate (eGFR) and to identify the independent factors for selected MBR sections in the ESKD patients.

RESULTS

All sections of the ONH in the ESKD patients were significantly lower than those in the control subjects. MBR-Choroid was not significantly different between the control and ESKD groups. The single regression analyses revealed that MBR-Tissue had the strongest correlations with creatinine and the eGFR. The multiple regression analyses revealed hematocrit, creatinine, and eGFR as factors independently contributing to the MBR-Tissue. The inferior section of MBR-Tissue was most strongly correlated with creatinine and the eGFR.

CONCLUSION

The MBRs in the ONH of the ESKD patients decrease compared with control subjects and the inferior section of MBR-Tissue is correlated with serum creatinine and eGFR.

Effects of brinzolamide on rabbit ocular blood flow in vivo and ex vivo

AIM

To investigate if significant improvement of optic disc blood flow (ODBF) occurs after instillation of brinzolamide onto rabbit eyes.

METHODS

Testing of bilateral intraocular pressure (IOP) and left ODBF in 10 male rabbits took place every 3h over a 24h period. Brinzolamide (1% ophthalmic solution, two drops at 9:00 and 21:00) was administered to the left eye. ODBF, assessed using laser speckle flowgraphy, was determined as the mean blur rate (MBR). Furthermore, the effect of brinzolamide on isolated rabbit ciliary arteries using isometric tension recording system was performed.

RESULTS

After brinzolamide instillation, IOP was significantly decreased in the left eye. MBR-vessel was greater at 18:00 and 21:00 (P<0.05) than in the controls. MBR-tissue and MBR-average were greater at 18:00 (P<0.05) than in the controls. For isolated arteries pre-contracted with a high-K solution, brinzolamide induced concentration-dependent relaxation, reaching 46.1%±9% (n=21) at 1 mmol/L. In Ca²⁺-free solutions, incubation with brinzolamide suppressed 1 µmol/L histamine-induced contractions (P<0.05).

CONCLUSION

Brinzolamide decreases IOP and increases ocular blood flow. The direct vasodilatory effect of brizolamide is mediated by suppression of Ca²⁺ release from intracellular calcium stores.