Optic disc rim area to retinal nerve fiber layer thickness correlation: comparison of diabetic and normal tension glaucoma eyes

Optic Disc Microvasculature Dropout in Preperimetric Glaucoma

PRCIS

Optic disc microvasculature dropout (MvD-D) was associated with worse disease severity in pre-perimetric glaucoma. MvD-D was not accompanied by focal lamina cribrosa defect or parapapillary deep-layer microvasculature dropout in 62.3% and 71.0% of eyes, respectively.

PURPOSE

To investigate factors associated with optic disc microvasculature dropout (MvD-D) in patients with preperimetric primary open angle glaucoma (PPG).

METHODS

One hundred thirty nine eyes of PPG patients were categorized according to the presence of MvD-D with optical coherence tomography angiography (OCTA). Factors including visual field (VF) mean deviation (MD), retinal nerve fiber layer (RNFL) thickness, focal lamina cribrosa (LC) defect, optic disc hemorrhage (DH), and parapapillary deep-layer microvasculature dropout (MvD-P) were compared between eyes with and without MvD-D.

RESULTS

MvD-D was observed in 69 PPG eyes (49.6%). Compared with eyes without MvD-D, the ones with MvD-D had a significantly thinner RNFL in all areas except the nasal sector, worse VF MD, and a focal LC defect and MvD-P ( P <0.05): male gender also was more highly prevalent. A considerable number of eyes with MvD-D lacked focal LC defect (62.3% [43/69]) or MvD-P (71.0% [49/69]), while a few eyes without MvD-D had focal LC defect (10.0% [7/70]) or MvD-P (2.9% [2/70]). In a multivariable logistic regression analysis, male gender (odds ratio [OR], 3.96; P <0.001), worse VF MD (OR, 1.44; P =0.019), thinner global RNFL (OR, 1.13; P <0.001), higher prevalence of focal LC defect (OR, 3.71; P =0.014) and MvD-P (OR, 7.85; P <0.001) were significantly associated with MvD-D.

CONCLUSIONS

MvD-D was related to worse disease severity in patients with PPG, and often was not accompanied by focal LC defect or MvD-P. This suggests that impaired optic disc circulation can be an early sign of glaucoma without noticeable changes in functional or structural features (i.e., VF, focal LC defect, MvD-P).

Increased Indoleamine 2,3-Dioxygenase and Quinolinic Acid Expression in Microglia and Müller Cells of Diabetic Human and Rodent Retina

Purpose

We investigated the relationship between inflammation, neuronal loss, and expression of indoleamine 2, 3-dioxygenase (IDO) and quinolinic acid (QUIN) in the retina of subjects with type 1 diabetes (T1D) and type 2 diabetes (T2D) and in the retina of rats with T1D.

Methods

Retinas from T1D (n = 7), T2D (n = 13), and 20 age-matched nondiabetic human donors and from T1D (n = 3) and control rats (n = 3) were examined using immunohistochemistry for IDO, QUIN, cluster of differentiation 39 (CD39), ionized calcium-binding adaptor molecule (Iba-1, for macrophages and microglia), Vimentin (VIM; for Müller cells), neuronal nuclei (NeuN; for neurons), and UEA1 lectin (for blood vessels).

Results

Based on morphologic criteria, CD39⁺/ionized calcium binding adaptor molecule 1(Iba-1⁺) resident microglia and CD39⁻/Iba-1⁺ bone marrow–derived macrophages were present at higher density in T1D (13% increase) and T2D (26% increase) human retinas when compared with controls. The density and brightness of IDO⁺ microglia were increased in both T1D and T2D human retinas. The intensity of QUIN⁺ expression on CD39⁺ microglia and VIM⁺ Müller cells was greatly increased in both human T1D and T2D retinas. T1D retinas showed a 63% loss of NeuN⁺ neurons and T2D retinas lost approximately 43% when compared with nondiabetic human retinas. Few QUIN⁺ microglia-like cells were seen in nondiabetic retinas, but the numbers increased 18-fold in T1D and 7-fold in T2D in the central retina. In T1D rat retinas, the density of IDO⁺ microglia increased 2.8-fold and brightness increased 2.1-fold when compared with controls.

Conclusions

Our findings suggest that IDO and QUIN expression in the retinas of diabetic rats and humans could contribute to the neuronal degeneration that is characteristic of diabetic retinopathy.

Retinal nerve fiber layer loss is associated with urinary albumin excretion in patients with type 2 diabetes

OBJECTIVES

To identify the factors associated with retinal nerve fiber layer (RNFL) loss in patients with type 2 diabetes.

DESIGN

Cross-sectional study.

PARTICIPANTS

Ninety-six nonglaucomatous patients with type 2 diabetes without renal impairment (estimated glomerular filtration rate, ≥60 ml/minute per 1.73 m(2)).

METHODS

Eyes were divided into 2 groups based on the presence or absence of RNFL defects detected by red-free retinal fundus photography. All participants underwent an eye fundus examination, and the urinary albumin-to-creatinine ratio (ACR) was determined. A cardiovascular autonomic function test was performed using the following heart rate variability parameters: expiration-to-inspiration ratio, response to the Valsalva maneuver, and standing. Multiple logistic regression analyses were performed to determine potential risk factors related to the presence of RNFL defects in these patients.

MAIN OUTCOMES AND MEASURES

The association between RNFL defects and diabetic complications.

RESULTS

Among the patients, 43 (44.8%) had localized RNFL defects (group 1), whereas the others (55.2%) did not (group 2). The RNFL defects occurred more frequently on the superior side (75.6% and 71.0% in right and left eyes, respectively) compared with the inferior side (13.8% and 0.0% in right and left eyes, respectively). Patients with RNFL defects (group 1) had significantly higher rates of diabetic retinopathy (60.5%) compared with those without RNFL defects (group 2; 32.1%; P = 0.007). The urinary ACR was significantly higher in patients with RNFL defects than in those without defects (45.3±72.1 μg/mg vs. 15.4±17.3 μg/mg creatinine, respectively; P = 0.015), whereas autonomic function test grading was similar between the groups. The urinary ACR was the only factor related to visual field defect location in both univariate (P = 0.021) and multivariate (P = 0.036) logistic regression analyses after adjusting for age; gender; presence of diabetic retinopathy; diabetes duration; smoking; statin use; and antiplatelet, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker treatment.

CONCLUSIONS

Urinary albumin excretion was associated with nerve fiber layer loss in patients with type 2 diabetes. Careful examination of the optic nerve head may be necessary, particularly in patients with type 2 diabetes exhibiting albuminuria.