Asymmetric severity of diabetic retinopathy in Waardenburg syndrome: response to authors

Correspondence: Aditi Gupta Shri Bhagwan Mahavir Department of Vitreoretinal Services, Sankara Nethralaya, 18 College Road, Chennai 600 006, Tamil Nadu, India Tel +91 44 2827 1616 Fax +91 44 2825 4180 Email [email protected] We read with great interest the recent article by Kashima et al, in which the authors report a case of asymmetric severity of diabetic retinopathy in Waardenburg syndrome. We want to highlight some concerns regarding this report. Previous reports have described many systemic and local factors associated with the development of asymmetric diabetic retinopathy. These include myopia $5 D, anisometropia .1 D, amblyopia, unilateral elevated intraocular pressure, complete posterior vitreous detachment, unilateral carotid artery stenosis, ocular ischemic syndrome, and chorioretinal scarring. In any suspected case of asymmetric diabetic retinopathy, it is prudent to rule out the abovementioned factors first. In the present case, although the authors clearly mention the absence of internal carotid and ophthalmic artery obstruction on magnetic resonance angiography, it would have been more informative if the authors had also provided the refractive error, intraocular pressure, and posterior vitreous detachment status of both the eyes. Likewise, it would have been useful to note the arm-retina time and retinal arteriovenous filling time in both the eyes on fundus fluorescein angiography, which is usually used to diagnose ocular ischemic syndrome by monitoring extension of the retinal circulation time, including time of blood circulation from the arm to the retina and the retinal arteriovenous filling time. The mere absence of internal carotid obstruction on magnetic resonance angiography cannot rule out the presence of ocular ischemic syndrome because, rarely, ocular ischemic syndrome can also occur secondary to other causes, such as arteritis. Comparing the arm-retina time and retinal arteriovenous filling time on fundus fluorescein angiography in both the eyes would be more helpful to rule out ocular ischemic syndrome. Kashima et al report the presence of more advanced diabetic retinopathy in the eye with sectoral iris hypochromia than the eye in which iris hypochromia was total. Presence of asymmetric diabetic retinopathy in association with iris heterochromia has been reported earlier in Fuchs’ heterochromic cyclitis, in which the affected eye (hypochromic iris) had nonproliferative diabetic retinopathy and the fellow eye had peripheral diabetic retinopathy. Although the authors hypothesized that Fuchs’ heterochromic cyclitis protected the affected eye from progression to peripheral diabetic retinopathy, they could not find a clear mechanism for the same. The cases reported by Kashima et al and Murray et al bear similarities, and may suggest a common link in understanding the pathogenesis behind asymmetric severity of diabetic retinopathy. Dovepress