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Neal Kansara, Ingrid U Scott, Esther M Bowie; Association Between Stage of Diabetic Retinopathy and Iris Thickness. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5316.
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While the effects of diabetes mellitus on some parts of the eye, such as the retina, have been well-described, there is little information regarding the potential association between diabetic retinopathy and iris thickness. We tested the hypothesis that more severe diabetic retinopathy is associated with a thicker iris.
Patients with a history of type 1 or type 2 diabetes mellitus and evaluated in a retina clinic of an academic medical center in October-November 2018 were invited to participate in the study. Patients with prior incisional ocular surgery or other ocular trauma, concurrent diseases or taking medications that affect pupil dilation, a history of keratoconus, or a history of non-open angle glaucoma were excluded from the study. Patients underwent complete ophthalmologic evaluation by a retina specialist, who classified each eye as having either no diabetic retinopathy (DR), non-proliferative diabetic retinopathy (NPDR), or proliferative diabetic retinopathy (PDR). Anterior segment optical coherence tomography (OCT) was performed to measure iris thickness at the dilator muscle and sphincter muscle regions using ImageJ software prior to dilation. The dilator muscle region (DMR) was defined as the area halfway between the scleral spur and iris pupillary margin. The sphincter muscle region (SMR) was defined as the area 750 um from the iris pupillary margin. All measurements in ImageJ software were made by a single researcher.
The study included 33 eyes classified into the following groups: PDR (n=6), NPDR (n=9), and no DR (n=18). Mean SMR thicknesses (in mm) of the nasal iris in the PDR, NPDR, and no DR groups were 0.56, 0.57, and 0.58 respectively; mean DMR thicknesses of the nasal iris were 0.46, 0.51, and 0.46; mean SMR thicknesses of the temporal iris were 0.48 mm, 0.49 mm, and 0.49; and mean DMR thicknesses of the temporal iris were 0.45, 0.46, and 0.42, respectively. For each iris location, there was no significant difference among the three DR groups with respect to the iris thickness.
Preliminary results show no significant association between stage of DR and iris thickness in either the SMR or DMR of the temporal or nasal iris. Recruitment is ongoing.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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