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Vujosevic, Stela, MD, PhD*; Muraca, Andrea, MD*; Alkabes, Micol, MD*; Villani, Edoardo, MD†,‡; Cavarzeran, Fabiano, ScD§; Rossetti, Luca, MD; De Cilla', Stefano, MD*,**

doi: 10.1097/IAE.0000000000001990
Original Study: PDF Only

Purpose: To assess and compare early modifications in inner retinal layer thickness and optical coherence tomography angiography parameters in patients with diabetes mellitus (DM) Types 1 and 2 without clinical signs of diabetic retinopathy.

Methods: Ninety eyes of 90 subjects (24 Type 1 DM, 36 Type 2 DM, and 30 healthy controls) were prospectively evaluated with spectral domain OCT, swept-source OCT angiography, and color fundus photography (on the same day). Retinal nerve fiber layer, ganglion cell layer (GCL+), and nerve fiber layer + GCL+ (GCL++) thickness were automatically determined by the instrument in the 1, 3, and 6 central mm. On OCT angiography, the following parameters were evaluated: area of foveal avascular zone, number of focally dilated endings of the capillaries (detected only on OCT angiography), presence of regular/irregular foveal avascular zone, capillary loss, and capillary network irregularities in the superficial capillary plexus (SCP) and deep capillary plexus (DCP).

Results: Ganglion cell layer+ (P = 0.0099) and GCL++ (P = 0.0367) were significantly thicker in DM Type 1 versus DM Type 2 in 1 central mm, after adjustment for age and DM duration. The area of foveal avascular zone was significantly larger in DM Type 1 versus controls in both SCP and DCP and in DM Type 1 versus Type 2 only in DCP (P < 0.05 for all); the number of focally dilated endings of the capillaries was higher in DM Type 1 versus controls in both SCP and DCP (P < 0.01 for all); and in DM Type 2 versus controls only in DCP (P = 0.007). Perifoveal capillary loss in SCP and inner retinal layer thickness had the highest correlation in both DM types.

Conclusion: There are specific neural and microvascular modifications even before clinical signs of diabetic retinopathy in DM Types 1 and 2. Perifoveal capillary loss in the SCP is highly correlated with inner retinal layer. These data may help in characterization of patients at the preclinical stage of diabetic retinopathy.

*Eye Unit, University Hospital Maggiore della Carita', Novara, Italy;

Department of Clinical Science and Community Health, University of Milan, Milan, Italy;

Eye Clinic, San Giuseppe Hospital, Milan, Italy;

§Department of Neuroscience, University of Padova, Padova, Italy;

Eye Clinic, San Paolo Hospital, University of Milan, Milan, Italy; and

**Department of Health Science, University East Piedmont “A. Avogadro”, Novara, Italy.

Reprint requests: Stela Vujosevic, MD, PhD, University Hospital Maggiore della Carita', Eye Unit, Corso Mazzini 18, 28100 Novara, Italy; e-mail:

None of the authors has any financial/conflicting interests to disclose.

© 2019 by Ophthalmic Communications Society, Inc.