Scars That Save: The Paradox of Laser in PDR

This case involved bilateral Proliferative Diabetic Retinopathy (PDR), where Panretinal Photocoagulation (PRP) was performed on both eyes in a total of two sittings.

Key point: PRP should be applied at least 3 disc diameters (DD) away from traction bands.

In cases with flat fibrous membranes, it is advisable to perform laser treatment close to the membrane.

Both eye status post PRP

This case requires right eye Pars plana vitrectomy with extreme guarded visual prognosis.

and there were skip areas in nasally and in extreme periphery in left eye due to vitreous hemorrhage may requires tight PRP.

Principle of PRP (Panretinal Photocoagulation) Laser

Panretinal photocoagulation works on the principle of selective destruction of peripheral ischemic retina to reduce retinal metabolic demand and VEGF (Vascular Endothelial Growth Factor) production.

By ablating the non-perfused peripheral retina, PRP:

• Decreases ischemia-driven angiogenic stimulus.

• Causes regression of neovascularization in PDR.

• Prevents further proliferation and complications such as vitreous hemorrhage or tractional retinal detachment.

Mechanism: The laser energy is absorbed mainly by melanin in the retinal pigment epithelium (RPE) and hemoglobin in the choroid, producing a controlled thermal burn. This destroys photoreceptors (high oxygen consumers), improving oxygen diffusion from the choroid to the inner retina.

Converting hypoxic retina to anoxic retina.