**19. Severe NPDR and PDR in an eye with DME**

Nowadays these patients seldom come without any previous treatment. Incomplete retinal laser and particularly interrupted intravitreal anti-VEGF injections for PDR have resulted in sight-threatening complications. PRP, primary vitrectomy or pharmacotherapy, alone or in combination, have been proposed with excellent outcome. The choice greatly depends on the ability of the patient to visit the clinic for regular follow up or emergency. Serious comorbidities and psychiatric diseases are associated with lengthy admissions and recuperation – and lack of eye treatment. Such patients will benefit from completion of the PRP and a longer-acting intravitreal medication while they are still ambulant. The main concern with PRP is the peripheral visual field (VF) loss associated with photocoagulation burns. A recent ad hoc review of DRCR.net Protocol S data reports decline of the pericentral and peripheral visual field 5 years after treatment with 20 ranibizumab injections to a level close to the pattern in eyes with PRP and 7 ranibizumab injections, suggesting that there are factors besides PRP associated with VF loss in eyes treated for PDR. In the longitudinal model describing total VF point score loss, the amount of loss depended on the type of laser treatment applied. On average, additional PRP sessions were associated with less VF loss than an initial PRP session, and endolaser application during vitrectomy was associated with more loss than an initial PRP session. The losses may be direct and immediate effects of heavier vs. lighter photocoagulation or reflections of delayed deleterious effects of the treatments, conditions associated with the persistence or return of neovascularization necessitating additional treatment, cataract progression, or, in the case of endolaser with vitrectomy, adverse effects of vitreous hemorrhage or the surgical procedure, such as cataract [48]. In practice, early, gradual and sparing laser technique with smaller spot size and less duration, particularly after intravitrel pharmacotherapy, is seldom associated with significant field loss – these defects appear after severe ischemia and correspond to non-perfusion areas.
