Microalbuminuria is associated with increased choroidal thickness in type 1 diabetes mellitus patients without diabetic retinopathy
Year: 2017
Type: letter
Study design: Observational Study
Abstract: Clinical, histopathologic and experimental findings suggest that diabetic choroidopathy is related to diabetic retinopathy (DR); association between choroidal thickness (CT) and diabetes or DR is controversial (Regatieri et al. 2012; Vujosevic et al. 2012; Farias et al. 2014). Even though DR and diabetic nephropathy share similarities in the pathogenesis, they may not be present simultaneously in type 1 diabetes (T1D). Microalbuminuria is an early marker of diabetic nephropathy and endothelial dysfunction. We measured CT in 40 T1D patients (19 microalbuminuric and 21 normoalbuminuric) without DR, as well as in 24 age-matched healthy subjects, to evaluate the relationship between microalbuminuria and CT. Exclusion criteria were refractive errors above ±3 dioptres, smoking habit, media opacities, and present or past history of ocular diseases other than minor ammetropies. All patients underwent dilated fundus examination, digital retinography (Canon CR-2 Digital Retinal Camera, Canon Inc, Tokyo, Japan) and spectral domain optical coherence tomography (Cirrus SD-OCT, Carl Zeiss Meditec, Jena, Germany) at the same time of day to avoid CT diurnal variation. Spectral domain optical coherence tomography (SD-OCT) analysis was based on high-definition scans from HD 5 Line Raster Scans – Enhanced Depth Imaging protocol at 180°. Choroidal thickness (CT) was manually measured by the same experienced examiner, masked to the clinical characteristics of the participants, from the outer edge of the hyper-reflective retinal pigment epithelium to the inner sclera at 500-μm intervals temporally and nasally to the fovea. Sclero-choroidal junction was well identified in all patients. Measurements were made perpendicular to the RPE-choriocapillaris complex at five points: subfoveal (SF), nasally at 500 μm (N500) and 1000 μm (N1000) from the fovea and temporally at 500 μm (T500) and 1000 μm (T1000) from the fovea, as previously described (Regatieri et al. 2012). One eye per patient was randomly assigned for statistical analysis. A high intragrading agreement was reached for measurements at all points. There were no differences in baseline characteristics between T1D groups (p > 0.05) [microalbuminuric versus normoalbuminuric (mean ± SD), respectively: age 21.4 (8.7) versus 24.8 (7.1) years; diabetes duration 11.2 (5.1) versus 12.7 (6.1) years; HbA1c (%) 9.9 (2.0) versus 9.0 (2.8); glomerular filtration rate (mL/min/1.73 m2) 125.3 (35.4) versus 141.3 (37.4); central macular thickness (μm) 242 (18) versus 240 (23); 13 patients were of female gender on each group (68.4 versus 61.9%)]. Most patients in both groups had poor glycaemic control (HbA1C ≥ 9%). Patients with arterial systemic hypertension (two microalbuminuric and one normoalbuminuric) were under control with ACE inhibitors. Choroidal thickness (CT) was higher in all points in diabetic patients [diabetic versus controls (mean ± SD), respectively (Fig. 1): 375 (72) versus 323 (64) μm SF (p = 0.006), 346 (68) versus 292 (65) μm N500 (p = 0.003), 334 (72) versus 264 (72) μm N1000 (p = 0.000), 362 (71) versus 319 (62) μm T500 (p = 0.016) and 356 (73) versus 316 (64) μm T1000 (p = 0.030)]. Subfoveal choroid was thicker in microalbuminuric as compared to normoalbuminuric T1D patients (mean ± SD), respectively: 390 (84) versus 361 (58) μm. Choroidal thickness (CT) had no independent association with age, diabetes duration, gender, glomerular filtration rate, diabetes duration, HbA1C, systemic hypertension or central macular thickness in these fairly homogenous groups. Age and diabetes duration are known confounding variables in CT analysis (Vujosevic et al. 2012); a thinner choroid was reported in a group of type 2 DM microalbuminuric patients who were older than ours (Farias et al. 2014). Both albuminuria and DR have been associated with inflammation, endothelial damage and impaired regulation of extracellular matrix remodelling (Rajab et al. 2015). Increased CT could be associated with increased vascular permeability and/or vasodilation, autonomic dysregulation or increased oncotic pressure (Nickla & Wallman 2010). Even though CT was measured manually and only horizontal measures were evaluated, our findings suggest that an altered CT may be a surrogate for the systemic vascular changes that occur in diabetes and that microalbuminuria should be acknowledged as a confounding factor in CT evaluation of diabetic patients. It remains unclear whether changes in CT are predictive of DR.
Source: Acta Ophthalmologica
DOI: 10.1111/aos.13462
Authors: Fernando Korn Malerbi, Caio Vinicius Regatieri, João Roberto de Sa, Paulo Henrique Morales, Michel Eid Farah, Sergio Atala Dib
Institution: Universidade Federal de São Paulo
Language: English
Subfield: Ophthalmology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2663669959