|Year : 2014 | Volume
| Issue : 6 | Page : 669-670
Diagnostic enigmas of retinopathy: New dimensions
Editor, Indian Journal of Ophthalmology, Chairman, Managing Director, Aditya Jyot Eye Hospital Pvt Ltd, Wadala, Mumbai, Maharashtra, India
|Date of Web Publication||8-Jul-2014|
Editor, Indian Journal of Ophthalmology, Chairman, Managing Director, Aditya Jyot Eye Hospital Pvt Ltd, Wadala, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Natarajan S. Diagnostic enigmas of retinopathy: New dimensions. Indian J Ophthalmol 2014;62:669-70
Diabetic retinopathy is the most serious ophthalmic complication of diabetes mellitus (DM). Although the diagnosis and treatment, target the vascular abnormalities in proliferative diabetic retinopathy (PDR), it is actually the concurrent inflammation and neurodegeneration that precipitates PDR. The common feature in a PDR is neovascularization that leads to visual loss due to vitreous hemorrhage, tractional retinal detachment, and glaucoma.  Several classes of growth factors have been implicated to be upregulated resulting in neovascularization, one of which is interleukins. Cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), interleukin-10 (IL-10) and interferon-gamma (IF-γ) regulate cells and have immune and inflammatory properties.  These inflammatory mediators induce oxidative stress within the retinal cells and induce nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB), leading to diabetic retinopathy.  Also, they stimulate the collagen synthesis including the glial cells and fibroblasts resulting in proliferation and contraction. Many studies have attempted to establish the association between serum interleukin levels and PDR, but hardly any exists on vitreous levels. , Mao et al., in this issue evaluated the levels of vitreous IL-1β and IL-10 in patients with PDR using a cohort study design. The authors have found elevated levels of both IL-1β and IL-10 in patients with PDR as compared to normal controls. The same has been confirmed by previous studies with IL-1β antagonist too.  The study is limited in assessing only these two cytokines while a large prospectively controlled study evaluated around 27 cytokines including IL-1β, monocyte chemoattractant protein-1, IF-γ-induced protein-10 and vascular endothelial growth factor (VEGF) which have been found to be elevated.  Nevertheless, the present study may pave the way for evaluating these new targets in managing diabetic retinopathy.
DM can damage the optic nerve by either raising the intraocular pressure or by causing optic neuropathy.  As the diabetic retinopathy leads to a severe, irreversible visual loss, research is underway in early detection of the condition. One of the changes that serve as a signal is the intra retinal layer segmentation.  Demir et al., in this issue evaluated the thickness of retinal nerve fiber length and ganglion cell complex in patients with type 2 diabetes mellitus (T2DM) using optic coherence tomography (OCT). The authors have found a nonsignificant thinning of the retinal layers irrespective of diabetic retinopathy status. The literature is inconclusive about this entity in patients with DM. Previous studies have found either no change in the thickness of these layers or only segmental changes. , This necessitates a large controlled study to be undertaken in this arena.
Hypertension is another leading cause of retinopathy. Not only has it led to visual impairment but is also a risk indicator of systemic morbidity and mortality.  Hypertensive retinal vascular signs can manifest as arteriolar changes such as generalized/focal arteriolar narrowing, arteriovenous nicking and arteriolar wall opacification or can be more advanced retinopathy lesions like microaneurysms, blot and flame-shaped hemorrhages, cotton-wool spots, hard exudates, and optic disk swelling.  Of these signs except for optic disk swelling, all others remain nonspecific in diagnosing the condition. As there is a change in the resistance of the orbital arteries, recent studies focus on evaluating the same in hypertensive patients. , But these studies are limited in recruiting a mix population of hypertensive individuals irrespective of their age and ophthalmic complications of hypertension where the findings may differ. Akal et al., in this issue published a study which evaluated the resistive index (RI) in geriatric population comparing those with and without retinopathy using color doppler imaging. The authors have found an increase in RI of posterior cerebral artery in hypertensive patients as compared to controls, indicating that it can be an early marker for orbital complications in hypertension.
As we look at the pandemic of DM, it would be immensely beneficial to look at ways to prevent these complications caused by oxidative stress rather than just scavenge the free radicals.
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