João Paulo Cunha

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.

Alzheimer's disease: A review of its visual system neuropathology. Optical coherence tomography-a potential role as a study tool in vivo.

Alzheimer’s disease (AD) is a prevalent, long-term progressive degenerative disorder with great social impact. It is currently thought that, in addition to neurodegeneration, vascular changes also play a role in the pathophysiology of the disease. Visual symptoms are frequent and are an early clinical manifestation; a number of psychophysiologic changes occur in visual function, including visual field defects, abnormal contrast sensitivity, abnormalities in color vision, depth perception deficits, and motion detection abnormalities. These visual changes were initially believed to be solely due to neurodegeneration in the posterior visual pathway. However, evidence from pathology studies in both animal models of AD and humans has demonstrated that neurodegeneration also takes place in the anterior visual pathway, with involvement of the retinal ganglion cells’ (RGCs) dendrites, somata, and axons in the optic nerve. These studies additionally showed that patients with AD have changes in retinal and choroidal microvasculature. Pathology findings have been corroborated in in-vivo assessment of the retina and optic nerve head (ONH), as well as the retinal and choroidal vasculature. Optical coherence tomography (OCT) in particular has shown great utility in the assessment of these changes, and it may become a useful tool for early detection and monitoring disease progression in AD. The authors make a review of the current understanding of retinal and choroidal pathological changes in patients with AD, with particular focus on in-vivo evidence of retinal and choroidal neurodegenerative and microvascular changes using OCT technology.

Diabetes Mellitus as a Risk Factor in Glaucoma's Physiopathology and Surgical Survival Time: A Literature Review

ABSTRACT Glaucoma is a multifactorial condition under serious influence of many risk factors. The role of diabetes mellitus (DM) in glaucoma etiology or progression remains inconclusive. Although, the diabetic patients have different healing mechanism comparing to the general population and it has a possible-negative role on surgical outcomes. This review article attempts to analyze the association of both diseases, glaucoma and DM, before and after the surgery. The epidemiological studies, based mainly in population prevalence analyzes, have shown opposite outcomes in time and even in the most recent articles also the association remains inconclusive. On the contrary, the experimental models based on animal induced chronic hyperglycemia have shown an important association of both diseases, explained by common neurodegenerative mechanisms. Diabetic patients have a different wound healing process in the eye viz-a-viz other organs. The healing process is more and it results in lower surgical survival time, higher intraocular pressure (IOP) levels and, therefore, these patients usually need more medication to lower the IOP. Both randomized and nonrandomized retrospective and experimental molecular studies have shown the association between DM and glaucoma. Further studies are needed to get better explanations about outcomes on more recent surgical procedures and with the exponential use of antifibrotics. How to cite this article: Costa L, Cunha JP, Amado D, Pinto LA, Ferreira J. Diabetes Mellitus as a Risk Factor in Glaucoma’s Physiopathology and Surgical Survival Time: A Literature Review. J Curr Glaucoma Pract 2015;9(3):81-85.

OCT in Alzheimer’s disease: thinning of the RNFL and superior hemiretina

BackgroundPeripapillary retinal nerve fiber layer (pRNFL) and internal macular layer thinning have been demonstrated in Alzheimer’s disease (AD) with optical coherence tomography (OCT) studies. The purpose of this study is to compare the pRNFL thickness and overall retinal thickness (RT) in AD patients with non-AD patients, using spectral domain optical coherence tomography (SD-OCT) and determine the sectors most characteristically affected in AD.MethodsA cross-sectional study was performed to determine the pRNFL and overall macular RT thicknesses in AD and non-AD patients, attending a tertiary hospital center. For pRNFL, the global and six peripapillary quadrants were calculated, and for overall RT values, the nine Early Treatment Diabetic Retinopathy Study (ETDRS) areas were used. A multiple regression analysis was applied to assess the effects of disease, age, gender, spherical equivalent, visual acuity, intraocular pressure, axial length and blood pressure on pRNFL and overall macular RT. ResultsA total of 202 subjects, including 50 eyes of 50 patients with mild AD (mean age 73.10; SD = 5.36 years) and 152 eyes of 152 patients without AD (mean age 71.03; SD = 4.62 years). After Bonferroni correction, the pRNFL was significantly thinner for the AD group globally and in the temporal superior quadrant (10.76 μm and 20.09 μm mean decrease, respectively). The RT thickness was also decreased in superior sectors S3 and S6 (mean thinning of 9.92 μm and 11.65 μm, respectively). Spearman’s correlation coefficient showed a direct association between pRNFL in the temporal superior quadrant and RT in superior S6 and S3 sectors (rS = 0.41; p < 0.001 and rS = 0.28; p < 0.001, respectively).ConclusionsPatients with AD showed a significant thickness reduction in global and temporal superior quadrants in pRNFL and in superior pericentral and peripheral sectors of RT. These findings may reflect a peripapillary and retinal changes characteristic of AD, suggesting the importance of SD-OCT as a potential adjuvant in early diagnosis of AD. Further studies are needed to understand which retinal layers and macular sectors are more useful as potential ocular biomarker over time in AD.

Choroidal thinning: Alzheimer's disease and aging

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

Nanotechnology-Ocular Devices for Glaucoma Treatment: A Literature Review

ABSTRACT Nanotechnology enabled the development of materials and devices with great utility in different fields of medicine. By using engineered-based nano-devices and structures, human biological systems may be controlled and repaired at a molecular scale, ultimately leading to a biological benefit. In particular, in the field of glaucoma treatment, nanotechnology may, for example, enhance drug residence time on the ocular surface and ocular bioavailability, as well as improve surgical success by both optimizing postoperative scarring and providing a wider safety window. Further studies are still needed to entirely explain the pharmacodynamics of nanotechnology-based therapeutic approaches and prove their biological consequences in human eyes. This review aims to summarize the literature concerning the advances in nanotechnology, specifically regarding ocular devices applied to the treatment of glaucoma.

Alzheimer Disease: OCT Retinal and Choroidal Thickness

The aim of this study is to compare macular retinal layers and choroidal thicknesses of patients with Alzheimer’s disease (AD) with those of patients without other known ophthalmological pathology, using spectral domain optical coherence tomography. Multiple linear regression analysis was applied to assess the effects of age, gender, spherical equivalent, visual acuity, intraocular pressure, axial length and mean arterial pressure on macular retinal layers thickness. Fifty eyes of 50 patients (mean age 73.10; SD=5.36 years) with a diagnosis of mild AD and 152 eyes of 152 patients without AD (mean age 71.03; SD=4.62 years) were included. There was a thinning in the peripheral ring of the ganglion cell layer (GCL) in the AD group (S6 p < 0.001; T6 and N6 p = 0.001). In the superior sectors of the inner plexiform layer (IPL), differences between the two groups also remained statistically significant after Bonferroni correction (S3 p = 0.001 and S6 p < 0.001). In the outer layers we did not observe differences statistically significant for AD group. These layers’ thicknesses were associated with statistical significance with gender (in inner and outer nuclear layers), age and choroidal thickness (CT) (in photoreceptor layer). In the AD patients group, CT was significantly thinner than in the first group of patients without AD, in all 13 locations (p<0.001), and age was relevant factor. Patients with AD showed a significant reduction in retinal layers and choroidal thickness. The thinnest macular measurements were found mostly in the inner layers, GCL and IPL, at superior sectors (pericentral and peripheral rings). This thinning may reflect a retinal characteristic of AD, related with both primary retinal lesion and transsynaptic retrograde degeneration and the choroidal thinning probably reflects the importance of vascular factors in the pathogenesis of this disease.

Morphology of Trabeculectomy Filtering Blebs using Anterior Segment Optical Coherence Tomography: A Comparison of Two Methods

Anterior segment imaging optical coherence tomography (AS-OCT) can be a useful aid in glaucoma surgery. Recent studies have shown its importance in both the preoperative morphologic evaluation of glaucoma patients as well as postoperative evaluation of filtering bleb functionality. Our purpose is to evaluate posttrabeculectomy filtering and non-filtering bleb characteristics in both time-domain OCT (TD-OCT, VisanteTM, Carl Zeiss) and spectral-domain OCT (SD-OCT, Heidelberg Spectralis ® anterior segment module), assess the usefulness of AS-OCT in evaluating postoperative filtering bleb function and compare both methods results. AS-OCT as a useful exam in determining functioning and non-functioning bleb characteristics. SD-OCT with an anterior segment module had a better performance in examining fine bleb features and performed better than in previous studies in examining deeper structures.