Choroidal neovascularization is the leading causes of central vision loss in wet age-related macular degeneration (wAMD) patients. Smoking not only aggravates the incidence and severity of the choroidal neovascularization of wAMD, but also affects the clinical treatment, making the prognosis worse. Nicotine, as an important harmful substance in tobacco, is an easily addictive and highly toxic alkaloid. Animal experiments and clinical studies have confirmed that nicotine can aggravate wAMD by mediating angiogenesis through nicotinic acetylcholine receptor, bone marrow blasts, inflammation, complement system, etc. Therefore, in order to early take appropriate intervention measures to prevent and delay the development, we should actively explore the exact pathogenesis by which nicotine aggravates the choroidal neovascularization.

Objective:To observe the changes of macular morphology and blood flow after minimally invasive vitrectomy (PPV) in patients with severe non-proliferative diabetic retinopathy (sNPDR).Methods:A prospective clinical study. From January 2020 to April 2021, 17 consecutive sNPDR patients with 17 eyes who were diagnosed and received PPV treatment at the Zhongshan Ophthalmic Center of Sun Yat-sen University were included in the study. There were 12 males with 12 eyes and 5 females with 5 eyes; the average age was 55 years old; the average duration of diabetes was 11 years; the average glycosylated hemoglobin was 7.9%. Before the operation and 1, 3, and 6 months after the operation, all the affected eyes underwent best corrected visual acuity (BCVA), standard 7-field fundus color photography, and optical coherence tomography angiography (OCTA). An OCTA instrument was used to scan the macular area of the affected eye with in the range of 3 mm×3 mm to measure the central subfoveal thickness (CST), the thickness of the ganglion cell complex (GCC) in the macular area, the thickness of the retinal nerve fiber layer (RNFL), and the superficial capillary plexus (SCP) vessel density and perfusion density in the macular area, macular avascular zone (FAZ) area, a-circularity index (AI). Before the operation and 6 months after the operation, the least significant difference test was used for the pairwise comparison.Results:Before the operation, 1, 3, and 6 months after the operation, the FAZ area of the macular area were 0.34±0.14, 0.35±0.10, 0.37±0.10, 0.36±0.13 mm 2, respectively; AI were 0.52±0.13, 0.54±0.11, 0.57±0.10, 0.60±0.11; CST was 282.6±66.7, 290.4±70.9, 287.2±67.5, 273.2± 49.6 μm; GCC thickness were 77.1±15.5, 74.3±13.9, 72.6±16.2, 78.5±18.3 μm; the thickness of RNFL was 97.9±13.8, 101.3±14.6, 97.7±12.0, 96.1±11.4 μm, respectively. The overall blood flow density of SCP in the macula were (16.79±1.43)%, (16.71±1.82)%, (17.30±2.25)%, (17.35±1.22)%; the overall perfusion density were 0.32±0.02, 0.32±0.03, 0.33±0.03, 0.33±0.02, respectively. After the operation, the CST increased first and then decreased; the thickness of RNFL increased 1 month after the operation, and then gradually decreased. Comparison of the parameters before and 6 months after the operation showed that the AI improved, and the difference was statistically significant ( P=0.049); the difference in FAZ area and the thickness of CST, GCC, and RNFL was not statistically significant ( P=0.600, 0.694, 0.802, 0.712); There was no statistically significant difference in the retina SCP blood flow density and perfusion density in the macular area ( P=0.347, 0.361). Conclusion:Compared with before surgery, there is no significant change in macular structure and blood flow density in sNPDR patients within 6 months after minimally invasive PPV.