Macular Vessels Density Before and After PRP in Patients With Proliferative Diabetic Retinopathy
Condition: PRP
MeSH terms: Diabetic Retinopathy
Study type: Interventional

Summary: 
      In this study, OCTA is used to study the vascular changes following PRP in patients with PDR;
      regarding vessels density at 1 month and 6 months follow up period and measure superficial,
      deep, and outer retina for fovea, para-fovea and whole image.
    

Detailed description: 
      The global prevalence of diabetes mellitus in 2019 is estimated to be 9.3% (463 million
      people).1 Diabetic retinopathy (DR) is microangiopathy characterized by capillary non-
      perfusion, microaneurysms (MAs), and retinal ischemia. 2It may cause many complications, such
      as diabetic macular edema (DME) and diabetic macular ischemia (DMI).3 Capillary ischemia
      decreases the nutrition of the retina and causes hypoxia which results in increased level of
      vascular endothelial growth factor (VEGF), which promotes angiogenic responses causing both
      neovascularization (proliferative diabetic retinopathy, PDR) and vascular permeability
      (macular edema).

      Panretinal photocoagulation (PRP) by argon or diode laser is the standard treatment for
      proliferative diabetic retinopathy. It improves oxygenation to the ischemic retina.
      Destruction of the highly active photoreceptor cells is the suggested mechanism of action for
      PRP. Subsequently, production of vascular endothelial growth factor (VEGF), the key player in
      neovascularization process, is reduced leading to regression of new vessels.5

      PDR eyes have an overall lower blood flow than normal or non-PDR eyes, parallel to the higher
      level of retinal ischemia and disease severity. With regression of these neovascular and
      shunt vessels following PRP, normalization of flow in the macula may reverse the ischemia and
      decrease the stimulus for new blood vessel formation. Closure of intraretinal microvascular
      abnormalities and neovascularization would theoretically increase overall resistance to flow
      and, combined with the constriction of the large vessel in response to increased oxygen in
      the inner retina, collectively decrease the overall blood flow.6 While most previous studies
      have explored the large vessel effects of PRP, the development of ocular coherence tomography
      angiography (OCTA) allowed the study of microvascular retinal changes in a detailed manner.
      It is a non-invasive modality that allows vascular mapping with high speed and quality and
      promotes visualization of vascular system in different retinal and choroidal levels. Several
      investigations have demonstrated the competence of OCTA in the quantification of
      microvascular density, choroidal flow area, and foveal avascular zone (FAZ) area in diabetic
      patients.
    

Intervention name(s): PRP was done using visulas green laser machine (Carl Zeiss Meditec AG Geoschwitzer Str. 51-52,07745 jena, Germany)
Intervention type(s): Other
Intervention description(s): PRP was done using visulas green laser machine (Carl Zeiss Meditec AG Geoschwitzer Str. 51-52,07745 jena, Germany)
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: OCTA; PRP