Retinal Neurodegeneration in Diabetic Patients Without Diabetic Retinopathy

Purpose

To compare the thickness of all retinal layers between a nondiabetic group and diabetic patients without diabetic retinopathy (DR).

Methods

Cross-sectional study, in which all subjects underwent an ophthalmic examination including optical coherence tomography. After automatic retinal segmentation, each retinal layer thickness (eight separate layers and overall thickness) was calculated in all nine Early Treatment Diabetic Retinopathy Study (ETDRS) areas. The choroidal thickness (CT) also was measured at five locations. Generalized additive regression models were used to analyze the data.

Results

A total of 175 patients were recruited, 50 nondiabetic subjects and 125 diabetic patients without DR, stratified into three groups according to diabetes duration: group I (<5 years, n = 55), group II (5-10 years, n = 39), and group III (>10 years, n = 31). Overall, groups I and III of diabetic patients had a decrease in the photoreceptor layer (PR) thickness, when compared with the nondiabetic subjects in six ETDRS areas (P < 0.0007). Patients with more recent diagnosis (group I) had thinner PR than those with moderate duration (group II). Interestingly, patients with longer known disease (group III) had the thinnest PR values. There were no overall differences in the remaining retinal parameters.

Conclusions

Retinal thickness profile is not linear throughout disease duration. Even in the absence of funduscopic disease, PR layer in diabetic patients seems to differ from nondiabetic subjects, thus suggesting that some form of neurodegeneration may take place before clinical signs of vascular problems arise.

Retina and Choroid of Diabetic Patients Without Observed Retinal Vascular Changes: A Longitudinal Study

PURPOSE

To identify changes in choroidal thickness (CT) and all retinal layers of diabetic patients without diabetic retinopathy (DR) after 1 year of follow-up.

DESIGN

Prospective observational cohort study.

METHODS

Overall, 125 diabetic patients without DR were included. Two visits were scheduled: the first visit (V1) and a second visit after 12 months (V2). At both visits, patients received a complete ophthalmologic evaluation that included OCT. Each retinal layer thickness was calculated for 9 ETDRS sectors, and CT was measured at 13 locations. Generalized linear mixed-effects models were used.

RESULTS

Of the 125 patients, 103 completed the study, and 9 of the 103 developed DR (8.7%). CT was significantly higher at V2 than at V1, with an average value of 10-17 μm at almost half the locations (500, 1000, and 1500 μm temporal; 500 and 1000 μm nasal; and 1000 μm superior to the fovea) (P < .001-.003). The thicknesses of the ganglion cell layer (I3 and N6 sectors), inner plexiform layer (S6 and N6 sectors), inner nuclear layer (T6 and N6 sectors), and outer plexiform layer (S6 sector), as well as the overall retinal thickness (RT) (S3, N3, I3, S6, and T6 sectors), were decreased at V2 (P < .001). Visible retinopathy was negatively associated with overall RT (central, S3, T3, I3, and N3 sectors, P = .004-.024) and the thickness of the ONL (T6 and I6 sectors, P = .007 and P = .009) and photoreceptor layer (N6 sector, P = .038). The presence of DR decreased the overall RT by 13.04-16.63 μm.

CONCLUSIONS

Diabetic patients without DR showed a thicker choroid and a thinner retina, particularly in inner layers, after 1 year of follow-up. These structural changes may correspond to the early neurodegenerative phase of DR.

Choroidal thinning: Alzheimer's disease and aging

INTRODUCTION

The purpose of this study was to measure and to compare macular choroidal thickness (CT) between patients with mild Alzheimer's disease (AD), patients without AD, and elderly patients.

METHODS

CT was measured manually in 13 locations at 500-μm intervals of a horizontal and a vertical section from the fovea. Linear regression models were used to analyze the data.

RESULTS

Fifty patients with a diagnosis of mild AD (73.1 years), 152 patients without AD (71.03 years), and 50 elderly without AD (82.14 years) were included. In the AD patients, CT was significantly thinner in all 13 locations (P < .001-comparing with age-match group), and comparing with the elderly group, a more pronounced difference was found in two locations temporal to the fovea.

DISCUSSION

Patients with AD showed a significant choroidal thinning even when compared with elderly subjects. The reduction of CT may aid in the diagnoses of AD, probably reflecting the importance of vascular factors in their pathogenesis.

A review of the electromyographic criteria in sexual performance

Given that the criteria for sexual performance including males considered normal is not clear in available literature, the authors sought a way to choose standards that would leave no doubts as far competence of performance and neurophysiological integrity in the control of sexual performance. The results found in more than 5,000 electromyographic evaluations on erectile dysfunction were equivalent to the results from a previous research, "The electromyographic gold standard to male sexual capacity", where normal males were evaluated according to the latency period, amplitude and morphology. To classify the results as "The gold standard", we used a selected and accurate method that excluded any doubts about the sexual performance. These men had the installation capacity, maintenance and control of their ejaculation, totally voluntary. The similarity between the clinical picture and the electromyographic events, suggests that the amplitude and the morphology, beyond the latency period, may indicate the quality of neurotransmission.

Quantitative analysis of blood-brain barrier damage in two models of experimental head injury in the rat

The integrity of the blood-brain barrier was studied in a new model of closed head injury, and in an established model of fluid percussion injury, in the rat. Brain injury in this new model is induced by impact and acceleration of the protected rat skull. Severe hypertension is not a characteristic of this new model as compared to the tremendous surge following direct dural percussion. This is important because of the well known sensitivity of the cerebral microvasculature for acute hypertension. Using a radioactive tracer technique the dysfunction of the barrier was quantified. It is shown that the BBB is temporarily damaged due to trauma, subsequent arterial pressure surge, as seen in the percussed animals, deteriorates the dysfunction of the barrier even further. This study indicates that vascular damage is a key event following head injury. Yet the concomitant basic pathophysiological sequelae of different models must be considered when studying barrier damage and cerebral edema following brain injury. Time window studies of the barrier indicate that the barrier seals within a few hours following severe concussive head injury, and in the absence of a hypertensive surge.