Cell Types of the Human Retina and Its Organoids at Single-Cell Resolution

Human organoids recapitulating the cell-type diversity and function of their target organ are valuable for basic and translational research. We developed light-sensitive human retinal organoids with multiple nuclear and synaptic layers and functional synapses. We sequenced the RNA of 285,441 single cells from these organoids at seven developmental time points and from the periphery, fovea, pigment epithelium and choroid of light-responsive adult human retinas, and performed histochemistry. Cell types in organoids matured in vitro to a stable "developed" state at a rate similar to human retina development in vivo. Transcriptomes of organoid cell types converged toward the transcriptomes of adult peripheral retinal cell types. Expression of disease-associated genes was cell-type-specific in adult retina, and cell-type specificity was retained in organoids. We implicate unexpected cell types in diseases such as macular degeneration. This resource identifies cellular targets for studying disease mechanisms in organoids and for targeted repair in human retinas.

Optical coherence tomography angiography (OCTA) as a new diagnostic tool in uveitis

Background

The broad spectrum of uveitis disorders requires a multimodal imaging approach in the daily practice of an ophthalmologist. As inflammatory conditions, they have in common an alteration in leukocyte migration. In this context, optical coherence tomography angiography (OCTA) might be of great value for diagnosing or following up patients with these disorders. To date, OCTA has rather been used as an additional tool besides the well-established diagnostic imaging tools, but its complementary diagnostic features become increasingly relevant, to follow disease activity and treatment response and for the understanding of pathomechanisms of various uveitis types.

This review summarizes the possible applications of OCTA and its advantages and disadvantages as opposed to dye-based angiographies in uveitic diseases.

Main body

Hitherto gold standards in the diagnostic workup of posterior or intermediate uveitis have been angiography on a dye-based method, which is fluorescein or indocyanine green. It gives information about the status of the blood-retinal barrier and the retinal and choroidal vasculature by visualizing diffuse leakage as a state of inflammation or complications as an ischemia or choroidal neovascularization. As noninvasive methods, fundus autofluorescence depicts the status of metabolic activity of the retinal pigment epithelium and OCT or enhanced depth imaging OCT, respectively, as a depth-resolving imaging method can supply additional information.

OCTA as a non-invasive, depth-resolution imaging tool of retinal and choroidal vessels adds detailed qualitative and quantitative information of the status of retinal and choroidal vessels and bridges the gap between the mentioned conventional diagnostic tools used in uveitis.

It is important, though, to be aware of its limitations, such as its susceptibility to motion artifacts, limited comparability among different devices, and restricted contribution of information regarding the grade of disease activity.

Conclusion

OCTA as a non-invasive, depth-resolution imaging tool can give qualitative and quantitative information about the status of retinal and choroidal vessels, but also has certain limitations. Employing OCTA as a complementary rather than exclusive tool, it can give important additional information about the macro- and microvasculature under inflammatory circumstances. Thereby, it also contributes to the understanding of the pathophysiology of various uveitis entities.

Interocular Visual-Field and Intraocular-Pressure Asymmetries in Normal-Tension-Glaucoma

To evaluate the role of intraocular-pressure (IOP) in the pathogenesis of glaucomatous damage in normal-tension-glaucoma, we investigated whether the eye with the higher IOP had more severe visual-field damage in 23 normal-tension-glaucoma patients. Twelve patients did have more severe visual-field defects in the eye with the higher IOP, but 11 had more severe defects in the eye with the lower IOP. There was no correlation either between IOP and visual-field damage (r = 0.16; p = NS) or between the interocular differences in IOP and in visual-field damage (r = 0.21; p = NS). Thus, although intraocular pressure may contribute to glaucomatous damage even in normal-tension-glaucoma patients, other factors must be involved as well.

Systemic Blood Pressure and Capillary Blood-Cell Velocity in Glaucoma Patients: A Preliminary Study

Systemic hypotension and vasospasm have both been suggested as risk factors for glaucomatous damage. Furthermore, a relationship between the incidence of vasospastic disorders and systemic hypotension has been reported. This preliminary study investigated the relationship between these two risk factors. In 20 glaucoma patients suspected to have vascular risk factors, time of blood-flow standstill was measured under cold provocation in nailfold capillaries and 24-hour blood pressure was monitored. Nine were high-tension glaucoma patients but progressing despite medically well-controlled intraocular pressure, and 11 had normal-tension glaucoma. Thirteen patients were vasospastic, and seven were not. Patients without vasospasm had a significantly lower mean systolic blood pressure during the daytime (113.4 +/- 7.1 mmHg) than vasospastic patients (122.6 +/- 12.8 mmHg), p = 0.026. The time of blood-flow standstill in vasospastic patients, however, correlated with the lowest individual systolic blood pressure reading (r = -0.56; p = 0.049). These low readings occurred mostly during the night ("deepers").

The prognostic value of retinal vessel analysis in primary open-angle glaucoma

PURPOSE

To analyse a prognostic value of initial retinal vessel flicker response for the 3-year development of functional (visual field) and morphological (nerve fibre layer thickness) damage progression in primary open-angle glaucoma patients.

PATIENTS AND METHODS

Initially, 70 patients were recruited, and flicker response was measured by standardized procedure with the retinal vessel analyser (RVA). Ocular coherence tomography of retinal nerve fibre layer (OCT RNFL) and a visual field testing were performed at beginning and every 6 months for 3 years; 56 patients completed the study.

RESULTS

No correlation was found between the progression of visual field (VF) mean defect and retinal nerve fibre layer (RNFL) thinning over 3 years on one and the maximal flicker reaction in arteries and veins on the other side (all p > 0.1). However, the calculated difference of examined parameters in the superior versus inferior retinal halves correlated significantly between the RNFL thinning and the initial maximal flicker response for arteries (p = 0.01) and veins (p = 0.003).

CONCLUSION

This longitudinal study did not find a general correlation between initial retinal vessel response to flicker light and the glaucoma damage progression measured by OCT and VF, hence limiting the relevance of the RVA device as a predictor of future glaucomatous damage.

Peripapillary retinal vessel diameter correlates with mfERG alterations in retinitis pigmentosa

PURPOSE

To investigate relationship between the peripapillary retinal vessel diameter and the residual retinal function, measured by mfERG, in patients with retinitis pigmentosa (RP).

PATIENTS AND METHODS

A cross-sectional study based on 23 patients with RP (43 eyes) and 20 controls (40 eyes) was performed. Retinal vessel diameters were measured using a computer-based program of the retinal vessel analyser (RVA; IMEDOS Systems UG, Jena, Germany). We evaluated the mean diameter in all four major retinal arterioles (D-A) and venules (D-V) within 1.0-1.5 optic disc diameters from the disc margin. The data were compared with the N1 amplitudes (measured from the baseline to the trough of the first negative wave), with the N1P1 amplitudes (measured from the trough of the first negative wave to the peak of the first positive wave) of the mfERG overall response and with the mfERG responses averaged in zones [zone 1 (0°-3°), zone 2 (3°-8°), zone 3 (8°-15°) and zone 4 (15°-24°)].

RESULTS

Mean (±SD) D-A and D-V were narrower in patients with RP [84.86 μm (±13.37 μm) and 103.35 μm (±13.65 μm), respectively] when compared to controls [92.81 μm (±11.49 μm) and 117.67 μm (±11.93 μm), respectively; the p-values between groups were p = 0.003 for D-A and p < 0.001 for D-V, linear mixed-effects model]. The RP group revealed clear differences compared to the controls: D-A and D-V became narrower with reduced mfERG responses. D-V correlated significantly with the overall mfERG N1 amplitudes (p = 0.013) and with N1P1 amplitudes (p = 0.016). D-V correlated with the mfERG amplitudes averaged in zones: (zone 2, 3 and 4; p ≤ 0.040) and N1P1 mfERG amplitudes (zones 1, 2, 3 and 4; p ≤ 0.013).

CONCLUSIONS

Peripapillary retinal vessel diameter is reduced in RP proportionally to functional alterations.

Reproducibility of retinal oximetry measurements in healthy and diseased retinas

PURPOSE

Retinal oximetry (RO) has been established as a non-invasive method to analyse oxygen saturation in retinal vessels. The aim of our study was to determine the reproducibility of RO images in healthy and in diseased retinas.

METHODS

A total of 61 right eyes (244 RO images) in 61 subjects (35♀, 26♂) were examined: 22 controls, 18 patients with glaucoma and 21 patients with inherited retinal diseases (IRDs). Four test-retest RO images were obtained in each subject. Oxygen saturation was measured with the oxygen saturation measurement tool of the Retinal Vessel Analyser (RVA; IMEDOS Systems UG, Jena, Germany). The test-retest standard deviation within the subject's (±SDw ) measurements (the mean vessel oxygen saturation in retinal venules and arterioles), its coefficient of variation (CoV) and the intraclass correlation coefficients (ICC) were analysed.

RESULTS

The average test-retest SDw in venules was ±2.52% (CoV = 4.35%) and in arterioles was ±1.67% (CoV = 1.76%). Among controls, glaucoma eyes and eyes with IRDs, the test-retest SDw in venules were ±2.33% (CoV = 4.48%), ±2.85% (CoV = 4.71%) and ±2.43% (CoV = 3.90%) (SDw p = 0.366 (CoV p = 0.452); one-way anova). The test-retest SDw in arterioles were ±1.65% (CoV = 1.80%), ±1.83% (CoV = 1.92%) and ±1.54% (CoV = 1.56%), respectively [SDw p = 0.762 (CoV p = 0.686)]. The ICCs in venules were 0.76 in controls, 0.69 in patients with glaucoma and 0.82 in patients with IRD. The ICCs in arterioles were, respectively, 0.92, 0.70 and 0.93.

CONCLUSION

The reproducibility of RO in healthy, as well as in diseased retinas, is excellent. In the glaucoma group, the lower standard deviation between subjects (SDb ) for arterioles contributes to the lower ICCs. Nevertheless, the measurements of oxygen saturation in arterioles seem more reliable when compared to venules.

Retinal vessel oxygen saturation and its correlation with structural changes in retinitis pigmentosa

PURPOSE

To study the influence of retinal structural changes on oxygen saturation in retinitis pigmentosa (RP) patients.

METHODS

Oximetry measurements were performed on 21 eyes of 11 RP patients and compared to 24 eyes of 12 controls. Retinal oxygen saturation was measured in all major retinal arterioles (A-SO₂) and venules (V-SO₂) with an oximetry unit of the retinal vessel analyser (IMEDOS Systems UG, Jena, Germany). Oximetry data were compared with morphological changes measured by Cirrus optical coherence tomography (OCT) (Carl Zeiss Meditec, Dublin, CA, USA, macular thickness protocol).

RESULTS

In RP patients, the retinal A-SO₂ and V-SO₂ levels were higher at 99.3% (p = 0.001, anova based on mixed-effects model) and 66.8% (p < 0.001), respectively, and the difference between the two (A-V SO₂) was lower at 32.5% (p < 0.001), when compared to the control group (92.4%; 54.0%; 38.4%, respectively). With the RP group, the A-V SO₂ correlated positively, not only with central macular thickness, but also with retinal thickness, in zones 2 and 3 (p = 0.006, p = 0.007, p = 0.014).

CONCLUSION

These data indicate that oxygen metabolism was altered in RP patients. Based on our preliminary results, retinal vessel saturation correlated with structural alterations in RP. This method could be valuable in monitoring disease progression and evaluating a potential therapeutic response.

[Analysis of retinal vein motion in glaucoma patients]

BACKGROUND

Analysis of retinal vein amplitude in eyes of glaucoma patients.

PATIENTS AND METHODS

Motion of retinal veins was captured by Retinal Vessel Analyzer in duration of 30 seconds. Inferotemporal vein segments of 500 micrometers length in the immediate vicinity of, as well as away from the optic disc were chosen. Time behavior of the average segment diameter was analyzed by the self made software: dominating frequency (heart rate) was determined by Fourier analysis, and based on this an average pulse form was produced. Difference between the highest and lowest diameter point was the subject of analysis in 25 eyes of 25 glaucoma patients and 25 age-sex-matched healthy controls.

RESULTS

Pulse amplitude of retinal veins in healthy eyes was higher than in glaucoma patients: in the optic disc vicinity the pulse amplitude relative to baseline was 2.6 ± 2.1% in control eyes and 1.4 ± 0.8% in glaucoma eyes (t-test, p = 0.009). Away from the disc, it was 1.7 ± 1.0% and 1.1 ± 0.5% respectively (p = 0.01).

CONCLUSIONS

Retinal veins in glaucoma eyes demonstrate lower pulse amplitudes than healthy eyes, indicating disturbance in venous outflow and increased intraluminal venous pressure.

Effect of ageing on the retinal vascular responsiveness to flicker light in glaucoma patients and in ocular hypertension

AIM

To evaluate the effect of ageing on the retinal vascular responsiveness to flicker light in glaucoma and ocular hypertension (OHT).

METHODS

Retinal vascular response to flicker was measured with the retinal vessel analyser in 56 healthy subjects (59 ± 9 years), 50 primary open-angle glaucoma (POAG) (60 ± 10 years) and 46 OHT patients (62 ± 9 years). In the glaucoma group, the less damaged eye; in the OHT group, the eye with the higher intraocular pressure; and in healthy controls, one randomly selected eye was considered. Parametric and non-parametric linear regression analysis, as well as a model of covariance analysis (ANCOVA) was used to evaluate the effect of age on the vascular response.

RESULTS

In all three groups (N=152) absolute (Pearson R: -0.19, p<0.019; Spearman R: -0.22, p<0.006) and relative change (Pearson R: -0.18, p<0.027; Spearman R: -0.21, p<0.010) were statistically associated with age. The ANCOVA showed no difference between the three groups in this regard (absolute change: p=0.43; relative change: p=0.51).

CONCLUSIONS

Vascular responsiveness to flicker light decreases with age in healthy individuals, in glaucoma patients and in OHT patients. This effect seems to be comparable between the tested groups, and age-related change in vascular responsiveness to flicker light seems an unlikely risk factor for glaucoma.

Postoperative microhyphema as a positive prognostic indicator in canaloplasty

PURPOSE

To assess risk factors for failure in canaloplasty.

METHODS

  Nonrandomized prospective study involving 51 eyes of 51 patients with medically uncontrolled primary open-angle glaucoma undergoing canaloplasty. Visual acuity, intraocular pressure (IOP) and slit-lamp examinations were performed before and after surgery at 1 and 7 days, and at 1 month and every 3 months thereafter. Factors like age, gender, preoperative IOP and microhyphema on day 1 were evaluated.

RESULTS

  The mean follow-up was 20.6 (SD 8.3) months. The mean preoperative IOP was 26.8 (SD 5.2) mmHg; the mean postoperative IOP was 8.4 (4.2) mmHg at day 1 and 12.7 (1.7) mmHg at month 24. Microhyphema was found in 40 patients (85.1%) on day 1 after surgery. The height of microhyphema was 1.8 mm ± 0.4 (SD) (range 1-2.5), and the time of resorption was 6.6 days ± 2.8 (SD) (range 3-14) on average. No recurrence of hyphema has been observed. IOP < 16 mmHg without medications depended significantly on the presence of microhyphema (hazard ratios, HR 0.03, 95% CI 0.01-0.25, p < 0.001), but not on age (HR 1.00, 95% CI 0.91-1.09, p = 0.32), preoperative IOP (HR 0.98, 95% CI 0.85-1.12, p = 0.80), cup-to-disc ratio (HR 0.15, 95% CI 0.00-20.01, p = 0.45) and gender (HR 0.24, 95% CI 0.05-1.12, p = 0.07). Factors like preoperative IOP, age, gender, cup-to-disc ratio were not associated with microhyphema. There were no significant differences between patients with versus without microhyphema in regard to age, preoperative IOP, morphological and functional glaucomatous damage, number of medications and postoperative day 1 IOP. However, patients with microhyphema had significantly fewer Nd:YAG goniopunctures after surgery than patients without microhyphema (p < 0.001).

CONCLUSION

Microhyphema the first postoperative day seems to be a significant positive prognostic indicator in uneventful canaloplasty in regard to IOP reduction, possibly representing a restored and patent physiologic aqueous outflow system.

Inactivation of MARCH5 prevents mitochondrial fragmentation and interferes with cell death in a neuronal cell model

PURPOSE

To study the impact of the mitochondrial ubiquitin ligase MARCH5 on mitochondrial morphology and induction of apoptosis using an in vitro model of neuronal precursor cells exposed to glaucoma-relevant stress conditions.

METHODS

RGC5 cells transfected with expression constructs for MARCH5, MARCH5(H43W), Dpr1(K38A) or vector control were exposed to either elevated pressure of 30 mmHg, oxidative stress caused by mitochondrial electron transport chain (ETC) inhibition, or hypoxia-reoxygenation conditions. Mitochondrial morphology of RGC5 cells was analyzed following staining of the mitochondrial marker cytochrome c and photoactivatable GFP (PAGFP) diffusion assay. Induction of apoptotic cell death in these cells was determined by analyzing the release of cytochrome c from mitochondria into the cytosol and flow cytometry.

RESULTS

Exposure of RGC5 cells to oxidative stress conditions as well as to elevated pressure resulted in the fragmentation of the mitochondrial network in control cells as well as in cells expressing MARCH5. In cells expressing inactive MARCH5(H43W) or inactive Drp(K38A), mitochondrial fragmentation was significantly blocked and mitochondrial morphology was comparable to that of control cells under normal conditions. Exposure of RGC5 cells to elevated pressure or oxidative stress conditions induced apoptotic cell death as assessed by cytochrome c release and DNA staining, while expression of dominant-negative MARCH5(H43W) or Drp1(K38A) did significantly delay cell death.

CONCLUSION

Preventing mitochondrial fragmentation through interference with the mitochondrial fission machinery protects neuronal cells from programmed cell death following exposure to stressors physiologically relevant to the pathogenesis of glaucoma.

Use of colour Doppler imaging in ocular blood flow research

The main objective of this report is to encourage consistent quality of testing and reporting within and between centres that use colour Doppler imaging (CDI) for assessment of retrobulbar blood flow. The intention of this review is to standardize methods in CDI assessment that are used widely, but not to exclude other approaches or additional tests that individual laboratories may choose or continue to use.

Heart-rate variability in women during 40-hour prolonged wakefulness

Heart-rate variability patterns of 18 women during a 40-h constant routine of prolonged wakefulness under controlled laboratory conditions were analyzed. The authors tested the circadian timing of the autonomic nervous system and the relationship between the sympathetic and vagal branches in women with both a functional disorder of vascular regulation (main symptom: cold hands and feet) and prolonged sleep onset and controls without these symptoms. Spectral analysis of R-R intervals during paced breathing episodes revealed significantly lower power values in the high-frequency band (HF; 0.15-0.4 Hz) but not in the low-frequency band (LF; 0.04-0.15 Hz), leading to a significantly elevated LF/HF ratio in the former group. A significant circadian rhythm in LF power and heart rate occurred in both groups, and a significant correlation was found between sleepiness and sympathovagal balance (r = .53, p < .05). These findings indicate not only an autonomic imbalance in the first group compared with controls, but also two strategies of the autonomic nervous system to fight against fatigue in women. One implies circadian control and the other homeostatic control, and both are reflected by the LF/HF ratio.

Thermal discomfort with cold extremities in relation to age, gender, and body mass index in a random sample of a Swiss urban population

Background

The aim of this epidemiological study was to investigate the relationship of thermal discomfort with cold extremities (TDCE) to age, gender, and body mass index (BMI) in a Swiss urban population.

Methods

In a random population sample of Basel city, 2,800 subjects aged 20-40 years were asked to complete a questionnaire evaluating the extent of cold extremities. Values of cold extremities were based on questionnaire-derived scores. The correlation of age, gender, and BMI to TDCE was analyzed using multiple regression analysis.

Results

A total of 1,001 women (72.3% response rate) and 809 men (60% response rate) returned a completed questionnaire. Statistical analyses revealed the following findings: Younger subjects suffered more intensely from cold extremities than the elderly, and women suffered more than men (particularly younger women). Slimmer subjects suffered significantly more often from cold extremities than subjects with higher BMIs.

Conclusions

Thermal discomfort with cold extremities (a relevant symptom of primary vascular dysregulation) occurs at highest intensity in younger, slimmer women and at lowest intensity in elderly, stouter men.

Vasospastic individuals demonstrate significant similarity to glaucoma patients as revealed by gene expression profiling in circulating leukocytes

PURPOSE

There is growing evidence that vasospatic individuals could be predisposed to develop glaucoma. Vasospastic deregulation is ensuing in activation of circulating leukocytes. In previous studies using "gene-hunting" strategies, we demonstrated stable alterations in gene expression profiles of circulating leukocytes isolated from glaucoma patients with vascular deregulation when compared to healthy individuals with no history of glaucomatous damage. The goal of this study was to look for possible similarities in gene expression profiles of circulating leukocytes in vasospastic individuals and glaucoma patients.

METHODS

Normal-tension (NTG) and high-tension (HTG) glaucoma patients as well as individuals with vascular deregulation (VD) and healthy controls were recruited for the gene expression analysis. The methodology of comparative Expression Array analysis followed by highly sensitive quantitative real-time PCR has been used.

RESULTS

Compared to the control group the expression of 146, 68, and 60 genes was found to be altered in NTG, HTG, and VD groups respectively. Thirty-four genes demonstrated similar expressional alterations in NTG, HTG, and VD groups versus controls, and only 21 genes demonstrated similar expressional alterations in NTG and HTG groups, having no overlap with the VD group.

CONCLUSIONS

This result indicates a potential predisposition of vasospastic individuals to glaucomatous optic nerve atrophy. The targeted expression profiles might be further considered for early/predictive glaucoma diagnosis.

Relationship between gender role, anger expression, thermal discomfort and sleep onset latency in women

BACKGROUND

Women with thermal discomfort from cold extremities (hands and feet; TDCE) often suffer from prolonged sleep onset latency (SOL). Suppressed anger could contribute to the genesis of both TDCE and prolonged SOL. The aim of the study was to test the hypothesis whether stereotypic feminine gender socialization (SFGS) is related to anger suppression (experienced anger inwards, Anger-In), which in turn could affect TDCE and SOL.

METHODS

148 women, a sub-sample of a larger survey carried out in the Canton Basel-Stadt (Switzerland), sent back detailed postal questionnaires about SOL, TDCE, anger expression (STAXI, state -trait -anger -expression -inventory) and SFGS using a gender power inventory, estimating the degree of gender specific power expression explicitly within women by stereotypic feminine or male attribution. Statistics was performed by path analysis.

RESULTS

A significant direct path was found from stereotypic feminine attribution to Anger-In and prolonged SOL. Additionally, a further indirect path from Anger-In via TDCE to SOL was found. In contrast, stereotypic male attribution was not related to Anger-In but was significantly associated with outwardly expressed anger.

LIMITATIONS

Self-reported data, retrospective cross-sectional survey, prospective studies are required including physiological measurements.

CONCLUSION

Stereotypic feminine gender socialization may play an important determinant for anger suppression, which subsequently can lead to thermal discomfort from cold extremities and prolonged sleep onset latency.

Relationship between ocular pulse amplitude and systemic blood pressure measurements

PURPOSE

This study aimed to determine whether ocular pulse amplitude (OPA) measured with dynamic contour tonometry (DCT) is related to systemic blood pressure (BP) parameters.

METHODS

Blood pressure was measured continuously and simultaneously with OPA in one randomly selected eye in 29 healthy subjects. Systemic parameters of interest were: systolic and diastolic BPs and their difference (BP amplitude), and left ventricle ejection time (LVET; defined as the time between the diastolic trough and the incisural notch in the BP curve). In addition, the axial length (AL) of the eye was measured. Associations between OPA, AL and systemic cardiovascular parameters were analysed in a multivariate regression model.

RESULTS

Measurements of OPA ranged from 1.0 mmHg to 4.9 mmHg (mean 2.3 +/- 0.9 mmHg, median 1.9 mmHg). In a univariate analysis with one predictor at a time, means of intraocular pressure (IOP) (p = 0.008), AL (p = 0.046) and LVET (p = 0.037) were significantly correlated with OPA, whereas systolic and diastolic BPs and their amplitude were not. A multiple linear regression analysis showed that mean IOP (p < 0.005), AL (p = 0.01) and LVET (p = 0.002) all independently contributed to OPA.

CONCLUSIONS

The OPA readings measured with DCT in healthy subjects were not related to BP levels and amplitude. It seems that the OPA strongly depends on the time-course of the cardiac contraction. Regulating mechanisms in the carotid system as well as scleral rigidity may be responsible for dampening the direct effect of BP variations.

[Response of retinal vessel diameter to flicker-light in vasospastics compared to healthy controls]

BACKGROUND

Vascular dysregulation is considered to be a risk factor in several ophthalmic diseases. The purpose of this study was to evaluate the reaction of retinal vessels to flicker light in otherwise healthy subjects with a vasospastic propensity.

PATIENTS AND METHODS

Thirty healthy Caucasians, aged between 18-35 years were recruited for this study and grouped into vasospastics, based on a history of frequent cold hands, even in summer, with concordant findings in nailfold capillary microscopy, or as controls, if such a history was absent. The reaction of the retinal vascular diameter to flicker light was observed in a distance of two to three discs diameters away from the optic nerve head with the retinal vessel analyser. Three phases of flicker light of twenty seconds followed by baseline light phases of eighty seconds were recorded. The maximal vasodilatory amplitude of each flicker phase was determined and the results averaged.

RESULTS

The maximal average dilatory amplitude at the arterial side reached (mean +/- SD) 2.9 +/- 1.7 % and 4.8 +/- 2.6 % of the baseline amplitude respectively in vasospastic subjects and in healthy controls (t = 2.34; p = 0.025). The reaction at the venous side was statistically comparable in both groups.

CONCLUSIONS

Otherwise healthy, vasospastic subject disclosed an altered reaction of the retinal vasculature to flicker light in this study.

Relation of body mass index and blood pressure to subjective and objective acral temperature

BACKGROUND

Vascular dysregulation, indicated by a positive history of cold extremities, has been postulated as a risk factor for a number of ocular diseases. In order to further characterize the phenotype of vasospastic persons, we tested the association between cold extremities, body mass index (BMI) and blood pressure (BP) in a cohort of healthy subjects.

PATIENTS AND METHODS

Questionnaire data were collected from one hundred and seventeen healthy subjects. Based on the history of cold hands and feet they were divided in three groups, reporting "never", "sometimes" and "always" having cold extremities. BP was measured sphygmomanometrically and as an objective measure of finger temperature, it was recorded at the fingertips with an infrared thermometer (IRT). Two-way analysis of variance with gender as one, and group selection as the second factor was performed separately for BMI and mean BP. The correlation of finger temperature with BMI and BP was analyzed by the Pearson regression.

RESULTS

Gender distribution was male/female = 41/16, 13/21 and 4/22, for the three groups, respectively, and average age 45.8 +/- 13.0 years. For BMI, factor groups was highly significant (p = 0.0012) with both genders behaving comparably (interaction p = 0.18). For BP the corresponding p values were: factor group p = 0.026, interaction p = 0.89. Correlation coefficients between IRT and BMI were 0.34 (p = 0.0002) and between IRT and BP 0.24 (p = 0.009).

CONCLUSION

A statistical significant association is present in healthy subjects between body mass index and blood pressure on one, and cold extremities on the other side, defined subjectively as well as measured objectively. This relationship is gender-independent.

Cold extremities and difficulties initiating sleep: evidence of co-morbidity from a random sample of a Swiss urban population

Difficulties initiating sleep (DIS) can frequently occur in psychiatric disorders but also in the general population. The primary vasospastic syndrome is a functional disorder of vascular regulation in otherwise healthy subjects complaining of thermal discomfort from cold extremities (TDCE). Laboratory studies have shown a close relationship between long sleep onset latency and increased distal vasoconstriction in healthy young subjects. Considering these findings, the aims of the Basel Survey were to assess the prevalence rates for DIS and TDCE and to determine whether both symptoms can be associated in the general population. In a random population sample of Basel-Stadt, 2800 subjects (age: 20-40 years) were requested to complete a questionnaire on sleep behavior and TDCE (response rate: 72.3% in women, n = 1001; 60.0% in men, n = 809). Values of DIS and TDCE were based on questionnaire-derived scores. In addition, TDCE was externally validated in a separate group of subjects (n = 256) by finger skin temperature measurements--high TDCE values were significantly associated with low finger skin temperature. A total of 31.1% of women and 6.9% of men complain of TDCE. In contrast, prevalence rates of DIS were only slightly higher in women in comparison to men (9.3% versus 6.7%, P < 0.1). Irrespective of gender, each seventh subject complaining of TDCE had concomitant DIS and the relative risk in these subjects was approximately doubled. Therefore, a thermophysiological approach to DIS may be relevant for its differential diagnosis and its treatment.

Comet assay analysis of single-stranded DNA breaks in circulating leukocytes of glaucoma patients

PURPOSE

To investigate the amount of single-stranded DNA breaks in circulating leukocytes of primary open-angle glaucoma (POAG) patients.

METHODS

A comparative quantification of DNA breaks was performed in circulating leukocytes of POAG patients and healthy controls. The following groups of subjects were compared: (1) POAG patients having primary vascular dysregulation (PVD), (2) POAG patients without PVD, (3) healthy controls with PVD, and (4) healthy controls without PVD. The damage to DNA resulting in single-stranded breaks was assessed by means of the alkaline comet assay in which the damaged DNA migrates out of the nucleus forming a tail, which can be quantified using image analysis. Damage was quantified as the comet tail moment, which represents the extent of DNA damage in individual cells.

RESULTS

Leukocytes of POAG patients exerted a significantly higher amount of comet tails, which are indicative of DNA damage, in comparison to control leukocytes (p<0.001). DNA breaks occurred particularly in the subgroup of POAG patients with PVD in comparison to glaucoma patients without PVD (p=0.002). In the control group, there was no significant difference between controls with PVD and controls without PVD (p=0.86).

CONCLUSIONS

POAG patients with PVD have a significantly higher rate of DNA breaks than both POAG patients without PVD and healthy controls with and without PVD.

Detection of visual field progression in glaucoma

BACKGROUND

The aim of this study was to compare an event analysis and a trend analysis for the detection of progression in glaucomatous visual field loss.

PATIENTS AND METHODS

Excluding initial fields (Octopus, Haag-Streit AG, Köniz, Switzerland), baseline was defined as the average result of the second and third examinations. Eyes with at least 6 additional fields entered the study. The event analysis used the method of the Collaborative Normal Tension Glaucoma Study, and the trend analysis was based on a point-wise linear regression analysis.

RESULTS

Of 251 glaucoma patients, 235 left eyes and 225 right eyes qualified for the study. Using the event analysis, 44 series suggested a progressive damage, while the point-wise regression approach disclosed only 14 progressing series. In 9 eyes, the two approaches were concordant. Among the latter, 1 - 5 additional fields were necessary in 7 series to disclose progression using the trend analysis. In one series, the event analysis showed progression 7 examinations later.

CONCLUSIONS

The point-wise linear regression analysis classified fewer cases as progressing than the event analysis and determined progression later.

Chronobiological characterization of women with primary vasospastic syndrome: body heat loss capacity in relation to sleep initiation and phase of entrainment

Women with primary vasospastic syndrome (VS), but otherwise healthy, exhibit a functional disorder of vascular regulation (main symptom: cold extremities) and often suffer from difficulties initiating sleep (DIS). Diverse studies have shown a close association between distal vasodilatation before lights off and a rapid onset of sleep. Therefore, we hypothesized that DIS in women with VS could be due to a reduced heat loss capacity in the evening, i.e., subjects are physiologically not ready for sleep. The aim of the study was to elucidate whether women having both VS and DIS (WVD) or not (controls) show different circadian characteristics (e.g., phase delay of the circadian thermoregulatory system with respect to the sleep-wake cycle). Healthy young women (n = 9 WVD and n = 9 control) completed a 40-h constant routine protocol (adjusted to habitual bedtime) before and after an 8-h sleep episode. Skin temperatures [off-line calculated as distal-proximal skin temperature gradient (DPG)] and core body temperature (CBT; rectal) were continuously recorded. Half-hourly saliva samples were collected for melatonin assay and subjective sleepiness was assessed on the Karolinska Sleepiness Scale (KSS). Compared with control, WVD showed no differences in habitual bed times, but a 1-h circadian phase delay of dim light-melatonin onset (hours after lights on: WVD 14.6 +/- 0.3 h; control 13.5 +/- 0.2 h; P = 0.01). Similar phase shifts were observed in CBT, DPG, and KSS ratings. In conclusion, WVD exhibit a phase delay of the endogenous circadian system with respect to their habitual sleep-wake cycle, which could be a cause of DIS.

Retrobulbar blood flow in idiopathic dilated episcleral veins and glaucoma

BACKGROUND

Dilated episcleral veins may occur in the presence of orbital tumors, carotid cavernous sinus fistula and other orbital obstructive lesions.

HISTORY AND SIGNS

A 39-year-old man had a history of a red left eye for two years. The visual acuity was 20/20, episcleral and conjunctival veins were dilated, and both the intraocular (24 mmHg) and episcleral venous (18 mmHg) pressures were increased. The canal of Schlemm was filled with blood, and glaucomatous damage was pronounced in the optic nerve head and the visual field of the left eye. The retrobulbar blood flow in the left eye was normal in the ophthalmic and central retinal arteries, but markedly decreased in the central retinal vein. There were no signs of fistula or shunts. The right eye was without any pathology. MR and catheter angiography of the head and orbit were both normal.

THERAPY AND OUTCOME

Following trabeculectomy, the intraocular and episcleral venous pressures dropped to 9 mmHg and 8 mmHg, respectively, at 6 months follow-up. The episcleral and conjunctival venous congestion regressed, and the blood flow in the central retinal vein increased.

CONCLUSION

The reason for the observed clinical picture (Radius-Maumenee syndrome) and haemodynamic improvement after reduction of the intraocular pressure is not clear. We outline a hypothesis involving an increase of the vascular resistance in the vortex veins and the superior ophthalmic vein with a shift in local blood volume and vascular pressure due to high intraocular pressure.

Retrobulbar blood flow in patients with cataract

OBJECTIVE

To investigate retrobulbar haemodynamics in patients with cataract.

SUBJECTS AND METHODS

Colour Doppler imaging of the ophthalmic artery was carried out on the eye scheduled for surgery in 30 patients with cataract and in one randomly selected eye of 100 healthy controls. The peak systolic velocity, mean velocity, end diastolic velocity and resistivity index in the ophthalmic artery were computed and adjusted for the influence of age and mean arterial pressure. Cataract type was recorded and lens opacity was measured with an opacity lensmeter. Odds ratio (OR) for cataract was analysed in a logistic regression model, depending on the adjusted blood-flow parameters, age and smoking status.

RESULTS

The mean (SD) age was 45.5 (17.7) and 67.6 (5.8) years in controls and patients with cataract, respectively (p<0.001). The female to male ratio was 54:46 and 13:17, respectively (p = 0.41). Significant predictors of cataract in a forward stepwise logistic regression analysis were age (OR = 1.194; 95% confidence interval (CI) = 1.103 to 1.292; p<0.001), smoking status (OR = 14.119; 95% CI = 2.753 to 72.398; p = 0.002) and mean blood-flow velocity in the ophthalmic artery (OR = 0.731; 95% CI = 0.607 to 0.881; p = 0.001). Adjusted mean velocity was significantly lower in patients with cataract, even when only age-matched (age >55 years) non-smokers (31 controls, 19 patients with cataract) were considered (p = 0.003). Lens opacity and the type of cataract had no influence on the present findings.

CONCLUSION

High mean velocity in the ophthalmic artery may be associated with a reduced risk of cataract.