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Shamira Perera, Aditi Mohla, Monisha Esther Nongpiur, Carol Yim-lui Cheung, Nia Milastuti, Valencia Foo, Ranjana Mathur; Variation in retinal oxygenation, retinal vasculature, and retinal nerve fiber layer thickness in patients with different grades of diabetic retinopathy. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3897. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the differences in retinal oxygenation, retinal vasculature, and retinal nerve fiber layer (RNFL) thickness in patients with different grades of diabetic retinopathy (DR).
This was a prospective case control study comparing 3 groups of patients seen in the diabetic retinopathy (DR) clinics. Group A patients had proliferative or severe non proliferative DR which would necessitate pan retinal photocoagulation (PRP). Group B patients had mild or moderate DR and did not require PRP. Group C patients underwent extensive PRP at least 2 years ago. All patients had retinal oxygenation measurements and retinal vessel caliber readings by Oxymap T1(Oxymap, Reykjavik, Iceland), optic disc stereophotographs, HD OCT (high Definition Optical Coherence Tomography) scans of the ONH by both Cirrus (Carl Zeiss Meditec Inc, Dublin, CA) and Spectralis (Heidelberg Engineering, Heidelberg, Germany). An analysis of variance (ANOVA) with Bonferroni method for multiple comparisons was used.
A total of 96 patients were included, 33 in Group A, 31 in Group B and 32 in Group C. Subjects in Group C were on average older than the other 2 groups (p=0.021). There was a significant difference in the retinal arteriole diameter in the 3 groups (A:111.6 microns ± 15.2, B:114.1 ± 15.1, C:103.8 ± 13.7; p=0.024), Group B Vs C was statistically significant, p=0.026. The oxygen saturation in arterioles and venuoles, intraocular pressure, rim area, cup volume, average cup disc ratio and biometric properties for all 3 groups were largely similar. There was a significant difference in the RNFL thickness in the 3 groups as measured by both HDOCTs , p<0.01 for both. The RNFL was at least 11 microns thicker in group A compared to the other groups by the Cirrus or 14 microns as measured by the Spectralis. Similarly, all quadrants of the RNFL were thicker in Group A compared to the other 2 groups (p<0.01 for all) by Cirrus and Spectralis except the nasal (p=0.0121 and p= 0.160)
The retinal arteriolar diameter seems to be most constricted in patients who have had PRP in the past. Patients with DR needing PRP have a thicker RNFL than either those with less severe DR or those having received PRP.
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