A B Figure 3 Disciform scars in 2 fellow eyes from the subgroup of 14 patients.A) Fundus picture of the largest scar that developed without previous intervention. B) Fundus picture of the largest scar that developed following previous laser treatment.This eye had received 2 sessions of laser photocoagulation for CNV. Abbreviation: CNV, choroidal neovascularization. retrospective nature and inclusion criteria of the study, might be partially responsible. It is generally believed that patients with poor response to therapy are more likely to be noncompliant with treatment plans. Thus it is quite possible that the majority of eyes that had signiﬁcant progression and poor visual outcome early after treatment failed to maintain the desired follow-up criteria of this study with either a short (less than 6 months) or an irregular (did not adhere to the TAP protocol) follow-up, leading to subsequent exclusion. The result of that would be the inadvertent selection of eyes with better response to PDT. The effect of PDT on lesion size and progression emphasized in this manuscript might be very signiﬁcant in determining the size of the DS and central scotoma that may ultimately develop in eyes with SFCNV. Disciform scarring is a frequent complication of neovascular maculopathy, Clinical Ophthalmology 2008:2(4) PDT-lesion size-disciform scar particularly AMD (Green and Enger 1993). The evolution of a DS secondary to CNV has been described by Gass (1967a, 1967b) who noted that repeated episodes of hemorrhage and exudation from these abnormal vessels in the subretinal and/or subpigment epithelial space result in retinal pigment epithelium (RPE) metaplasia with vascular and ﬁbroblastic in-growth from the choroid. The end result is a disciform maculopathy. Subsequent studies supported this theory (Teeters and Bird 1973; Green and Key 1977). Based on this, an intervention that limits the activity (bleeding and exudation) of CNV would be expected to favorably alter the evolution of the DS. PDT has been shown to cause endothelial cell damage and denudation of the vascular basement membrane with subsequent platelet aggregation, thrombus formation and vascular occlusion (Ghazi et al 2001). This effect, however, is short-lived because thrombus fragmentation and endothelial cell regeneration with re-population of the denuded basement membranes, result in re-perfusion of the occluded vessels following treatment (Ghazi et al 2001). This explains why repeated treatment sessions may be needed to maintain CNV non-perfusion. To understand the beneﬁcial effect of PDT on the evolution of the DS despite its short-lived effect, it is important to examine what happens to the CNV in between treatment sessions. At the vascular level, during the period that the neovessels are occluded following each treatment session, and before reperfusion and leakage re-occur, mild exudation and hemorrhage, if at all, takes place. At the cellular level, after each treatment, newly regenerated endothelial cells replace the treated necrotic cells. Evidence for this phenomenon can be observed experimentally as early as the third day following PDT and is complete by 2 weeks (Royster et al 1988). After the necrotic endothelial cells are regenerated, the following PDT session leads to their necrosis again, and the cycle continues with each treatment session. The newly regenerated, immature endothelial cells that replace the treated, mature cells might be less leaky. Evidence for this comes from previous ultrastructural studies which showed that development of endothelial fenestrations and loss of some of the surrounding pericytes are part of the maturation process of endothelial cells and capillaries lined by them (Ishibashi and Ryan 1992; Ishibashi et al 1995; Suzuki and Yoshida 1998). This may contribute to decreased exudation and hemorrhage in the early period following regeneration of treated capillaries and prior to their maturation. Therefore a logical implication would be that PDT could temporarily occlude active neovessels by virtue of thrombosis, and transform them into inactive vessels for at least a short period 777