Retinal Neurodegeneration In Type 2 Diabetes Mellitus Detected by Optical Coherence Tomography

Inclusion Criteria: * All patients with confirmed type 2 DM diagnosis of at least 6 months * Best-corrected visual acuity (BCVA) of 6/12 or higher (using a Snellen chart) in each eye * Intraocular pressure (by applanation) less than 21 mmHg. * Healthy controls had no record nor evidence of ocular or neurologic disease of any kind; their BCVA is \> 6/9 based on the Snellen scale. Exclusion Criteria: * presence or past history of moderate or severe non proliferative diabetic retinopathy or proliferative diabetic retinopathy , confirmed by indirect funduscopy or retinography images. * presence of significant refractive errors (≥5 diopters of spherical equivalent refraction or 3 diopters of astigmatism) * intraocular pressure ≥21 mmHg * media opacifications * concomitant ocular diseases, including history of glaucoma or retinal pathology * systemic conditions that could affect the visual system, including neurodegenerative disorders such as Parkinson's disease, multiple sclerosis, or dementia.