Associations of retinal neurovascular dysfunction with inner retinal layer thickness in non-proliferative diabetic retinopathy.

PURPOSE: Neurovascular coupling impairment and inner retinal layer thinning are early detectable retinal changes in diabetes, and both worsen during progression of diabetic retinopathy (DR). However, direct interactions between these features have not been investigated so far. Therefore, we aimed to analyze associations between the retinal functional hyperemic response to light stimulation and the thickness of individual neuroretinal layers in eyes with early non-proliferative DR. METHODS: Thirty patients with type 1 diabetes featuring mild (n = 15) or moderate (n = 15) non-proliferative DR and 14 healthy subjects were included in this cross-sectional study. Retinal vessel diameters were measured before and during illumination with flickering light using a dynamic vessel analyzer. Individual layer thickness in the macula was analyzed from spectral domain optical coherence tomography. RESULTS: Flicker light-induced vessel dilation was significantly reduced in patients compared to healthy controls (veins: 3.0% vs. 6.1%, p < 0.001; arteries: 1.3% vs. 5.1%, p = 0.005). Univariately, the response in retinal veins of diabetes patients correlated significantly with ganglion cell layer (GCL) thickness (r = 0.46, p = 0.010), and negatively with hemoglobin A1c (HbA1c) levels (r=-0.41, p = 0.023) and age (r=-0.38, p = 0.037), but not with baseline diameters, glucose levels, or diabetes duration. In a multiple regression model only GCL thickness (p = 0.017, ß = 0.42) and HbA1c (p = 0.045, ß=-0.35) remained significantly associated with the vascular flicker light response. CONCLUSION: The results indicate that thinner GCL and worse glycemic control both contribute to reduced retinal neurovascular coupling in patients with clinical signs of DR. Progression of neurovascular dysfunction in DR might be related to structural degeneration of the neurovascular complex in the inner retina.

Quality assurance via telephone interviews after cataract surgery: An explorative study.

INTRODUCTION: Cataract surgery is a relatively safe procedure with satisfactory postoperative results in most patients. However, in rare cases severe complications can occur shortly after the intervention. Therefore, patients are advised to undergo an ophthalmological examination postoperatively, which should be performed as soon as possible in case of emergencies. However, exactly when these follow-up visits should take place is still discussed. A time- and cost-saving alternative to this could be short-term postoperative telemedical approaches. The aim of this study was to analyze patient complaints as well as satisfaction with and the best timepoint to perform telephone calls after cataract surgery. METHODS: Patients scheduled for cataract surgery received a telephone call on the surgery day or the day after (study group) during which they were asked about complaints or additional examination visits. Patients without telephone calls served as control group. All patients had a follow-up visit one week after the intervention during which a questionnaire was filled out and the study group was asked about their satisfaction with the telephone calls. RESULTS: 181 patients were recruited in this study. Ocular surface problems were the most common postoperative symptom. More than 80% of the patients were very satisfied with the telephone calls, with patients being contacted on the day of surgery being more calmed than those called on the next day. No difference in additional and planned follow-up visits was found between the study and the control group (P > .40). Postoperative patient complaints (Phi 0.372, P < .001) and additional prescribed therapy (Phi 0.480, P < .001) were moderately associated with additional visits. CONCLUSION: Satisfaction with telephone reviews shortly after cataract surgery was very high and contacting patients on the evening of the day of the procedure could be a time- and cost-saving alternative to short-term in-house follow-up visits.

Rotational stability and capsular bag performance of a hydrophobic acrylic open-loop single-piece intraocular lens.

PURPOSE: To evaluate the rotational stability and capsular bag performance of a blue light-absorbing hydrophobic acrylic open-loop single-piece intraocular lens (IOL) with a blast-finished anchor wing haptic design during the first 6 postoperative months. METHODS: In this prospective clinical study, patients with age-related cataract and potential postoperative corrected distance visual acuity (CDVA) of 0.2 logMAR or better were included. The patients received a non-toric hydrophobic acrylic single-piece IOL with an axis mark (YST0.00; Nidek Co. Ltd, Japan). Surgeries were video-taped. Retroillumination images were acquired 1 h, 1 week and 6 months postoperatively. Rotational stability was assessed by precise image overlay. At 6 months, Purkinje meter measurements were performed to evaluate tilt and decentration. RESULTS: In total, 100 eyes of 77 patients were included in the analysis. Mean absolute rotation was 2.1 ± 1.7° (median 1.7, range: 0-7.9) at 6 months (1 h - 6 months postoperatively). IOL rotation was ≤3° and ≤6° in 74 (74%) and 98 (98%) eyes, respectively. Mean absolute IOL rotation from the end of surgery to 6 months was 2.5 ± 2.2° (median 2.3, range: 0-15.6; n = 78). Mean tilt (pupillary axis) and decentration were 4.1 ± 1.9° (median 4.0, range: 0.5-8.2) and 0.35 ± 0.17 mm (median 0.32, range: 0.06-0.91) respectively (n = 84). Postoperatively, 98 (98%) eyes achieved a CDVA of 0.2 logMAR or better, 95 (95%) of ≤0.1 and 81 (81%) of ≤0.0. CONCLUSIONS: This hydrophobic acrylic single-piece IOL showed an excellent rotational stability and capsular bag position with low tilt and decentration values.

Repeatability of biometry in patients with meibomian gland dysfunction before and after vectored thermal pulsation therapy: A randomized, controlled trial.

PURPOSE: To evaluate the effect of vectored thermal pulsation therapy (VTPT) on the repeatability of biometry readings of two different optical biometers in patients with meibomian gland dysfunction (MGD). METHODS: Patients affected by MGD were included in this prospective, randomized, controlled, investigator-masked study. One eye was randomized to VTPT (LipiFlow®, Johnson & Johnson), and the contralateral eye served as a control. Three visits were scheduled at baseline, 2 weeks and 3 months after the treatment. The main outcome parameter of the study was the repeatability of three calculations of emmetropic intraocular lens power (EIOLP) at the 3 months visit as compared to baseline using an optical biometer (IOLMaster® 700, Carl Zeiss Meditec AG). Repeatability of different keratometry values obtained by the optical biometer and a Placido-disc topographer (MS-39®, CSO) served as secondary outcome parameters. RESULTS: Twenty-nine patients were included in the final analysis. While tear film parameters improved in the study eyes, there were no significant differences regarding the repeatability of three EIOLP measurements between baseline and 3-months-visit in both eyes (p > 0.05) and keratometry measurements in both the optical biometer and the Placido-disc topographer. Remarkably, throughout all study visits, there were some outliers regarding the repeatability of measurements. CONCLUSION: While both devices showed high repeatability regarding EIOLP and keratometry, future studies are needed to detect high-risk patients for poor repeatability.

Occurrence of Corneal Staining after Cataract Surgery with and without Chitosan-N-Acetylcysteine Eye Drops.

INTRODUCTION: The objective of this study was to evaluate the prevalence of ocular surface damage assessed by corneal staining scores right after cataract surgery and whether it can be prevented using chitosan-N-acetylcysteine (C-NAC) eye drops. METHODS: We included patients scheduled for routine cataract surgery. Each patient was randomly assigned to one of three groups. Patients in group 1 underwent routine cataract surgery with no additional eye drops. In group 2, patients received C-NAC eye drops after cataract surgery, and in group 3, C-NAC was applied both before and after surgery. Both groups continued the treatment once daily for 4 days. Ocular surface alteration was assessed using the National Eye Institute (NEI) score, and the visual analog scale (VAS) was used to evaluate subjective complaints. RESULTS: Thirty-six patients were included in the final analyses. One hour after cataract surgery, a statistically significant increase in corneal fluorescein staining was observed in all groups, which decreased again after 1 week. There was no significant difference between the groups 1 h after cataract surgery, though a tendency toward lower NEI scores was observed during this time point in group 3. DISCUSSION: Cataract surgery induced ocular surface staining and subjective complaints after 1 h. However, the increase in VAS score was small and probably not clinically relevant. The application of perioperative C-NAC eye drops did reduce the rate of corneal staining after cataract surgery in a clinically relevant manner.

Effect of Treatment with Topical Azithromycin or Oral Doxycycline on Tear Film Thickness in Patients with Meibomian Gland Dysfunction: A Randomized Controlled Trial.

Purpose: This prospective, randomized, observer-masked, parallel-group study aimed to compare the effect of topical azithromycin and oral doxycycline on tear film thickness (TFT) and signs and symptoms of ocular surface disease (OSD) in patients with meibomian gland dysfunction (MGD). Methods: Patients were randomized to either receive topical azithromycin or oral doxycycline. After a baseline visit, three follow-up visits at intervals of 2 weeks were scheduled. Main outcome of the study was change in TFT as measured with ultrahigh resolution optical coherence tomography. Results: Twenty patients were included in the analysis. TFT significantly increased in both groups (P = 0.028 vs. baseline) with no difference between the groups (P = 0.096). As secondary outcomes, ocular surface disease index (OSDI) score and composite signs of OSD significantly decreased in both groups (P = 0.023 for OSDI and P = 0.016 for OSD signs vs. baseline). While eye-related adverse events (AEs) occurred more frequently in the azithromycin group, systemic AEs were more common in the doxycycline group. Conclusions: Both treatments improved signs and symptoms of OSD in patients with MGD with no difference between the groups. Due to the higher frequency of systemic side effects of doxycycline, azithromycin eye drops seem to be an alternative with comparable efficacy. Clinical Trial Registration number: NCT03162497.

Structure-Function Analysis of MP-3 Microperimetry versus Octopus Perimetry in Central Glaucomatous Visual Field Defects.

INTRODUCTION: The aim of this study was to compare the structure-function relationship with microperimetry and Octopus perimetry in primary open-angle glaucoma (POAG) patients with central visual field (VF) defects. METHODS: Forty eyes of 24 patients with POAG were enrolled. Circumpapillary retinal nerve fiber layer (cpRNFL) analysis measured by spectral-domain optical coherence tomography (SD-OCT) of the superotemporal, temporal, and inferotemporal optic-nerve head sectors were related to corresponding microperimetric and Octopus VF clusters using the G2 grid-pattern with dynamic strategy, respectively. The structure-function relationships of both devices were assessed via a segmented regression, as well as linear regression across overall SD-OCT cpRNFL values and outside normative (<1%) SD-OCT cpRNFL values. RESULTS: Linear and segmented regression fits were similar with both devices. Across overall cpRNFL sectorial values, structure-function relations for the superotemporal, temporal, and inferotemporal sectors were R2 = 0.176 (p = <0.001), R2 = 0.008 (p = 0.069), and R2 = 0.294 (p = <0.001) for microperimetry and R2 = 0.189 (p = <0.001), R2 = 0.020 (p = 0.002), and R2 = 0.326 (p = <0.001) for Octopus perimetry. For corresponding values outside normative limits (<1%), the relationships were R2 = 0.113 (p = <0.001), R2 = 0.001 (p = 0.836), and R2 = 0.420 (p = <0.001) for microperimetry and R2 = 0.192 (p = <0.001), R2 = 0.002, (p = 0.336), and R2 = 0.366 (p = <0.001) for Octopus perimetry. DISCUSSION/CONCLUSION: Structure-function analysis was similar for both devices. Fundus-tracking should be further evaluated in a longitudinal setting in patients affected by glaucoma.

New approach to quantifying acute stress in cataract surgeons to investigate the relationship between surgeon experience and intraoperative stress.

PURPOSE: To quantify intraoperative stress levels in cataract surgeons and investigate the relationship between intraoperative stress and surgeon experience. SETTING: Department of Ophthalmology, Hanusch Krankenhaus, Vienna, Austria. DESIGN: Prospective, observational case series. METHODS: 5 ophthalmologists with surgery experiences of 70 to 15 000 previous surgeries volunteered for this study. Surgeons' heart rate (HR) and heart rate variability (HRV) were measured during a total of 45 cataract surgeries. HR and HRV values were normalized to the minimal HR and maximal HRV of an overnight baseline measurement. The resulting normalized HR measure and HRV stress index are stress dependent and comparable between subjects. No case selection was performed. RESULTS: Less experienced surgeons showed higher HRV stress indices; differences between the surgeons with less than 180 and 500 surgeries and the 2 with 600 and 1500 surgeries, respectively, were statistically significant (α = 0.05). No statistically significant difference in stress indices was found between surgeons with 1500 and 15 000 surgeries, suggesting that there may be a plateau effect after 1500 surgeries. HRV stress indices and case times were negatively correlated with the logarithm of experience in the number of previously performed surgeries (r2 = 0.67 and 0.52). No significant stress buildup over multiple successive surgeries was found (α = 0.05). CONCLUSIONS: The new HRV stress index is a simple but powerful tool for quantifying intraoperative stress in cataract surgeons. Decreases in stress with increasing experience are congruent with previous works on general surgeons' stress and follow a similar timeline as previously published, proficiency-based learning curves for cataract surgery.

Effect of Iatrogenic Traction during Macular Peeling Surgery on Postoperative Microperimetry.

INTRODUCTION: Vitrectomy with peeling of epiretinal membrane (ERM) and internal limiting membrane offers the chance for improvement of metamorphopsia and visual acuity. Microscope integrated intraoperative optical coherence tomography (iOCT) enables real-time imaging of retinal alterations during peeling, such as intraoperative transient retinal thickening owing to tractional forces during peeling. The aim of our study was to measure the amounts of transient retinal thickening due to tractional forces during membrane peeling, as documented with iOCT, and to analyze possible effects on postoperative retinal function. METHODS: This prospective, monocenter study included patients scheduled for pars plana vitrectomy with membrane peeling due to an idiopathic ERM. During peeling, an iOCT device (ReScan700, Carl Zeiss Meditec AG) with continuous OCT-assistance during the peeling procedure, and video documentation of the peeling procedure, was used for the assessment of intraoperative transient retinal thickening owing to tractional forces during peeling. Directly before and 3 months after surgery, macular-OCT scans and microperimetry were performed. RESULTS: Twenty-five eyes of 25 patients were included in the study. Microperimetry could be performed in all patients, while iOCT documentation could be analyzed in 22 patients. Transient retinal thickening owing to tractional forces during peeling could be observed in 14 patients (64%), with a median thickening to 143% of the normal (preoperative) retinal thickness at that location (IQR 132-163). Six patients (24%) developed new deep microscotomata as seen in microperimetry 3 months after surgery, among them were 2 patients who also had transient retinal thickening during peeling. CONCLUSION: New deep microscotomata developed only in a minority of patients with transient retinal thickening owing to tractional forces during peeling.

Effect of Cataract Extraction on Retinal Sensitivity Measurements.

INTRODUCTION: Central and paracentral retinal function is often compromised in various retinal diseases. In these conditions, microperimetry is an important tool for assessing retinal sensitivity values. As retinal diseases are prevalent among the elderly, cataract often coexists. This study investigates the effect of cataract surgery on retinal sensitivity in patients with cataract without retinal disease. MATERIAL AND METHODS: A total of 30 patients already scheduled for cataract surgery were enrolled and microperimetry and visual acuity evaluation was performed before and after cataract extraction. The patients were allocated to 1 of 3 study groups in accordance with the main cataract subtype: nuclear, cortical, or posterior subcapsular (PSC) cataract. RESULTS: Visual acuity increased significantly after cataract surgery (from 0.34 to 0.00 logMar, p < 0.001, paired t test). Similarly, median retinal sensitivity increased significantly from 23 dB (IQR 21-25 dB) to 27 dB (IQR 25.75-28 dB) (p < 0.001, Wilcoxon test). The increase of retinal sensitivity after cataract surgery was highest in the PSC cataract group. CONCLUSION: This study showed an increase in retinal sensitivity values after cataract removal, especially in the PSC group. Therefore, coexisting cataract should be considered when interpreting microperimetry results.

Visual performance after bilateral toric extended depth-of-focus IOL exchange targeted for micromonovision.

PURPOSE: To evaluate overall patient satisfaction, spectacle independence, binocular visual acuity, rotational stability, prevalence of optical phenomena, and decentration and tilt after bilateral toric extended depth-of-focus intraocular lens (EDOF IOL) implantation targeted for micromonovision. SETTING: Department of Ophthalmology, Hanusch Hospital, Vienna, Austria. DESIGN: Prospective case series. METHODS: The study included 52 eyes of 26 patients with regular corneal astigmatism from 0.75 to 2.60 diopters (D) that were implanted bilaterally with a toric EDOF IOL targeted for micromonovision. Postoperative visual acuity, astigmatism reduction, rotation, tilt, decentration, spectacle independence, patient satisfaction, and photic phenomena were assessed. RESULTS: For the 52 eyes studied, binocular means expressed in logarithm of the minimum angle resolution for postoperative corrected distance, uncorrected distance, uncorrected intermediate, and uncorrected near visual acuities were -0.10 (±0.12), -0.01 (±0.13), 0.01 (±0.14), and 0.13 (±0.14), respectively. Mean refractive astigmatism reduction was 1.31 ± 0.67 D resulting in a mean refractive cylinder of 0.47 ± 0.46 D at the 3-month visit. Mean postoperative rotation was 3.5 ± 3.5 degrees, at the 3-month time point. Most prevalent dysphotopsia were halos, starburst, and glare affecting 6 (23%), 6 (23%), and 5 (19%) of 26 patients, respectively; 20 (77%) of 26 patients reported spectacle independence, with 19 (95%), 19 (95%), and 14 (70%) of 20 patients questioned being satisfied with distance, intermediate, and near vision, respectively. CONCLUSIONS: Toric EDOF IOL implantation targeted for micromonovision resulted in reliable reduction of preoperative astigmatism with a high degree of postoperative rotational predictability and centration, enabling functional distance, intermediate, and near vision, which manifested itself in high patient satisfaction.

Reproducibility of Microperimeter 3 (MP-3) Microperimetry in Open-Angle Glaucoma Patients.

PURPOSE: Primary open-angle glaucoma (POAG) is a chronic progressive optic neuropathy, leading to degeneration of retinal ganglion cells and characteristic morphological changes at the optic disc. In advanced stages of the disease, functional tests, such as standard automated perimetry (SAP), are the main diagnostic tools to detect progression. Compared to SAP, microperimetry offers fundus imaging with motion tracking to ensure precise stimulation of certain locations of the retina. Aim of the study was to assess reproducibility of microperimetry compared to SAP in patients with POAG. METHODS: This prospective monocenter study included patients suffering from POAG with visual field defects in the central 20° zone. After inclusion into the study, 3 consecutive study visits were scheduled within 1 month, assessing microperimetry and SAP at each visit. RESULTS: From 19 patients recruited, data from 18 patients could be analyzed. No significant difference between study visits could be detected in mean retinal sensitivity in microperimetry and SAP (microperimetry p = 0.401; SAP p = 0.644; Friedman's 2-way analysis of variance). The intraclass-correlation coefficient was 0.981 (95% CI 0.978-0.984) for microperimetry and 0.948 (95% CI 0.941-0.955) for SAP. Absolute agreement between deep scotoma points was found in 81 test locations (79%) in microperimetry and in 35 test locations (20%) in SAP (p = 0.003, chi-square test). CONCLUSIONS: Microperimetry and conventional perimetry showed high reproducibility, with slightly better performance of microperimetry. However, the reduced angle of visual field in microperimetry limits its application to central glaucomatous field damage.

One-Year Results after Internal Limiting Membrane Flap Transposition for Surgical Repair of Macular Holes with Respect to Microperimetry.

PURPOSE: Internal limiting membrane (ILM) flap transposition in surgical repair of macular holes represents a new technique offering good anatomical success rates with large macular holes. The aim of the study was to examine microperimetric outcomes 1 year after ILM flap transposition for surgical repair of macular holes. METHODS: Patients with idi-opathic macular holes scheduled for 23-G pars plana vitrectomy with ILM peeling, ILM flap transposition, and SF6 tamponade were examined in a prospective case series. Distance corrected visual acuity (DCVA), optical coherence tomography, and microperimetry were measured before and 1 year after surgery. RESULTS: In all eyes, closure of the macular hole could be achieved. While foveal sensitivity improved in 71%, perifoveal sensitivity improved in 86% of the cases. DCVA improved in 83% and was unchanged in 17% of the cases. CONCLUSIONS: Beside visual acuity, foveal and perifoveal macular sensitivity improved, underlining the functional success of surgery after ILM peeling with ILM flap transposition.

Intraoperative Optical Coherence Tomography-Guided Membrane Peeling for Surgery of Macular Pucker: Advantages and Limitations.

PURPOSE: Epiretinal membranes (ERMs) are a disorder leading to progressive vision loss and metamorphopsia. The gold standard in therapy is vitrectomy with membrane peeling. The aim of this study was to assess whether the use of intraoperative optical coherence tomography (iOCT), which allows tomographic visualization of the membrane during peeling, enables peeling without staining. METHODS: This prospective study included 30 eyes of 30 patients with idiopathic ERMs scheduled for surgery. Pars plana vitrectomy with iOCT was performed in all cases, whereas staining of ERMs was only performed if needed. Internal limiting membrane (ILM) peeling was performed in case of wrinkled retinal surface after peeling of ERMs. RESULTS: In 63% (n = 19) eyes the ERM could be peeled successfully without use of staining. Nevertheless, in 89% (n = 17) of patients having had ERM peeling without dye, staining of the ILM was performed afterwards for peeling the ILM. Best corrected visual acuity improved in 80% (n = 24) and remained unchanged in 7% (n = 2) 3 months after surgery. There were no significant differences in postoperative results between patients with and without staining for ERM peeling. CONCLUSIONS: Use of iOCT helps to complete ERM peeling in a majority of cases without use of a chromovitrectomy dye, but as iOCT fails to visualize the ILM, chromovitrectomy still facilitates macular surgery in a majority of cases.

Correlation of retinal neurodegeneration with measures of peripheral autonomic neuropathy in type 1 diabetes.

PURPOSE: To evaluate the relationship of neuroretinal layer thickness with sensitive measures of cardiovascular autonomic neuropathy in diabetic patients with non-proliferative diabetic retinopathy (NPDR). METHODS: Twenty-seven eyes of 27 patients with type 1 diabetes presenting with mild-to-moderate NPDR were compared to 27 healthy control (HC) eyes matched for age and gender. The total macular volume (TMV) and the volumes of individual neurosensory layers in the macula were analysed from spectral domain optical coherence tomography using automated layer segmentation. Cardiovascular autonomic regulation was assessed by short-term power spectrum analysis of heart rate variability (HRV) before, during and after an orthostatic challenge. RESULTS: The patients had an age of 46 ± 12 years and diabetes since 28 ± 9 years. Diastolic and mean arterial pressure was lower in the patients compared to HCs. TMV (r = 0.58, p = 0.002), inner plexiform layer volume (IPLV; r = 0.39, p = 0.047) and inner nuclear layer volume (INLV; r = 0.60, p = 0.001) were associated with reduced recovery of low-frequency (LF) spectral power of HRV after orthostatic load in diabetic patients but not in HCs. The response of LF spectral power during the orthostatic manoeuvre was blunted in patients compared to HCs (p = 0.02). Diabetes duration was negatively associated with TMV and INLV, whereas IPLV was significantly reduced in eyes with moderate NPDR compared to HCs. CONCLUSION: The results indicate a correlation between inner retinal tissue loss and diminished autonomic regulation in type 1 diabetic patients with mild-to-moderate NPDR. The observed changes can be interpreted as congruent early signs of retinal and systemic neuropathy in diabetes.

Test-Retest Reproducibility of the Microperimeter MP3 With Fundus Image Tracking in Healthy Subjects and Patients With Macular Disease.

PURPOSE: To evaluate the test-retest reproducibility of a novel microperimeter with fundus image tracking (MP3, Nidek Co, Japan) in healthy subjects and patients with macular disease. METHODS: Ten healthy subjects and 20 patients suffering from range of macular diseases were included. After training measurements, two additional microperimetry measurements were scheduled. Test-retest reproducibility was assessed for mean retinal sensitivity, pointwise sensitivity, and deep scotoma size using the coefficient of repeatability and Bland-Altman diagrams. In addition, in a subgroup of patients microperimetry was compared with conventional perimetry. RESULTS: Average differences in mean retinal sensitivity between the two study measurements were 0.26 ± 1.7 dB (median 0 dB; interquartile range [IQR] -1 to 1) for the healthy and 0.36 ± 2.5 dB (median 0 dB; IQR -1 to 2) for the macular patient group. Coefficients of repeatability for mean retinal sensitivity and pointwise retinal sensitivity were 1.2 and 3.3 dB for the healthy subjects and 1.6 and 5.0 dB for the macular disease patients, respectively. Absolute agreement in deep scotoma size between both study days was found in 79.9% of the test loci. CONCLUSION: The microperimeter MP3 shows an adequate test-retest reproducibility for mean retinal sensitivity, pointwise retinal sensitivity, and deep scotoma size in healthy subjects and patients suffering from macular disease. Furthermore, reproducibility of microperimetry is higher than conventional perimetry. TRANSLATIONAL RELEVANCE: Reproducibility is an important measure for each diagnostic device. Especially in a clinical setting high reproducibility set the basis to achieve reliable results using the specific device. Therefore, assessment of the reproducibility is of eminent importance to interpret the findings of future studies.

MACULAR CHOROIDAL VOLUME CHANGES AFTER INTRAVITREAL BEVACIZUMAB FOR EXUDATIVE AGE-RELATED MACULAR DEGENERATION.

PURPOSE: To evaluate the effect of intravitreal bevacizumab on the macular choroidal volume and the subfoveal choroidal thickness in treatment naïve eyes with exudative age-related macular degeneration. METHODS: The macular choroidal volume and the subfoveal choroidal thickness were measured using enhanced depth imaging optical coherence tomography. After a screening examination, each patient received 3 monthly intravitreal injections of 1.25 mg bevacizumab. One month after the third injection was a final assessment. RESULTS: Forty-seven patients with a mean age of 80 ± 6.4 years were included. The macular choroidal volume decreased significantly from median 4.1 mm (interquartile range 3.4-5.9) to median 3.9 mm (interquartile range 3.1-5.6) between the baseline and final examination (difference -0.46 mm, 95% confidence interval: -0.57 to 0.35, P < 0.001). Similarly, subfoveal choroidal thickness had decreased from 157.0 µm (interquartile range 116.0-244.5) at baseline to 139.0 µm (interquartile range 102.5-212.0) at the final examination (P < 0.001). Both parameters macular choroidal volume at baseline and subfoveal choroidal thickness at baseline were not associated with the response to treatment. CONCLUSION: The macular choroidal volume and the subfoveal choroidal thickness decreased significantly after 3 monthly bevacizumab injections for exudative age-related macular degeneration.

Relation of retinal blood flow and retinal oxygen extraction during stimulation with diffuse luminance flicker.

Cerebral and retinal blood flow are dependent on local neuronal activity. Several studies quantified the increase in cerebral blood flow and oxygen consumption during activity. In the present study we investigated the relation between changes in retinal blood flow and oxygen extraction during stimulation with diffuse luminance flicker and the influence of breathing gas mixtures with different fractions of O2 (FiO2; 100% 15% and 12%). Twenty-four healthy subjects were included. Retinal blood flow was studied by combining measurement of vessel diameters using the Dynamic Vessel Analyser with measurements of blood velocity using laser Doppler velocimetry. Oxygen saturation was measured using spectroscopic reflectometry and oxygen extraction was calculated. Flicker stimulation increased retinal blood flow (57.7 ± 17.8%) and oxygen extraction (34.6 ± 24.1%; p < 0.001 each). During 100% oxygen breathing the response of retinal blood flow and oxygen extraction was increased (p < 0.01 each). By contrast, breathing gas mixtures with 12% and 15% FiO2 did not alter flicker-induced retinal haemodynamic changes. The present study indicates that at a comparable increase in blood flow the increase in oxygen extraction in the retina is larger than in the brain. During systemic hyperoxia the blood flow and oxygen extraction responses to neural stimulation are augmented. The underlying mechanism is unknown.

Retinal oxygen extraction in humans.

Adequate function of the retina is dependent on proper oxygen supply. In humans, the inner retina is oxygenated via the retinal circulation. We present a method to calculate total retinal oxygen extraction based on measurement of total retinal blood flow using dual-beam bidirectional Doppler optical coherence tomography and measurement of oxygen saturation by spectrophotometry. These measurements were done on 8 healthy subjects while breathing ambient room air and 100% oxygen. Total retinal blood flow was 44.3 ± 9.0 µl/min during baseline and decreased to 18.7 ± 4.2 µl/min during 100% oxygen breathing (P < 0.001) resulting in a pronounced decrease in retinal oxygen extraction from 2.33 ± 0.51 µl(O2)/min to 0.88 ± 0.14 µl(O2)/min during breathing of 100% oxygen. The method presented in this paper may have significant potential to study oxygen metabolism in hypoxic retinal diseases such as diabetic retinopathy.