Ghazi et al Table 2 Average size of disciform scars following PDT (actual and potential) and without PDT (with and without prior laser) Disciform scar Disciform Disciform scar in Disciform scar Potential scar Potential scar in fellow eye scar in fellow fellow eyes with in study eyes post-PDT in study post-PDT in rest of subgroup eyes with no previous laser following PDT eyes of subgroup of study eyes of 14 patients previous laser treatment of 14 patients excluding 3 eyes Number of eyes 14 8 6 3 14 45 Average Size ± SD 5900 ± 1866 6200 ± 1493 5500 ± 2365 3200 ± 1345 3607 ± 1389 3579 ± 1473 (micron) Abbreviations: PDT, photodynamic therapy; SD, standard deviation. following regeneration and reperfusion by virtue of capillary immaturity. Hence, less stimulus for RPE metaplasia and ﬁbroblastic ingrowth as per Gass theory (Gass 1967a, 1967b), and a favorable inﬂuence on the evolution of the DS and central scotoma (Schmidt-Erfurth 1999). The findings in our study support this hypothesis. The average size of the DS that developed in 3 study eyes following PDT (3200 ± 1345 μm) was signiﬁcantly smaller than the average size of the scar in the fellow eyes of the subgroup of 14 patients (5900 ± 1866 μm), and particularly the 8 of 14 without previous intervention (6200 ± 1493 μm) (Tables 2, 3). In addition, the average size of the potential DS derived from the study eyes of the subgroup of 14 patients (3607 ± 1389 μm) was signiﬁcantly smaller than that of the scar in their fellow eyes (5900 ± 1866 μm) (Tables 2, 3). One could argue that this comparison may be biased because patients with a DS and central scotoma in their fellow eye might seek care earlier due to the slightest disturbance of vision in their good eye secondary to increased awareness. To eliminate such bias, we also compared the average size of the DS in the fellow eyes of the subgroup of 14 patients (5900 ± 1866 μm) to that of the potential scar in the study eyes of the rest of the patients who do not have a DS in their fellow eye. The latter was found to be 3579 ± 1437 μm and was also signiﬁcantly smaller (Tables 2, 3). Therefore, the potential scar in both instances was signiﬁcantly smaller than the DS in the fellow eyes of the 14 patients. This was also true when comparison was made with the 8/14 fellow eyes that had a DS without previous intervention (6200 ± 1493 μm) (Tables 2, 3). We also observed that there was no signiﬁcant difference between the average size of the scar in the 6/14 fellow eyes in which the scar developed following previous laser treatment (5500 ± 2365 μm) and that of the scar following PDT in the 3 study eyes that developed scarring (3200 ± 1345 μm), the study eyes of the subgroup of 14 patients (3607 ± 1389 μm), or the study eyes of the rest of the patients (3579 ± 1473 μm), respectively (Tables 2, 3). So it also appears that laser treatment, like PDT, might have a beneﬁcial effect on the evolution of the DS. This, again, we believe is the result of the interruption of the active exudative phase of the CNV that leads to the development of disciform maculopathy. One drawback of the subgroup analysis of our study is that the DS in the fellow eye of each of these 14 patients was already present at presentation. It was not prospectively observed to evolve; therefore, we could not tell with certainty whether the process started with SFCNV, or non-SFCNV with secondary subfoveal spread. Thus comparing disciform scars in these fellow eyes to actual and potential disciform scars secondary to documented SFCNV in the study eyes Table 3 Comparison between the average size of the disciform scar following PDT (actual and potential) and that without PDT (with and without prior laser). Statistical analysis, p-value* Disciform scar Potential disciform scar Potential disciform scar in 3 study eyes post-PDT in subgroup post-PDT in rest of study post-PDT of 14 study eyes eyes excluding 3 eyes Disciform scar in subgroup of 0.044 0.002 0.0001 14 fellow eyes Disciform scar in 8 fellow eyes 0.033 0.002 0.0004 with no prior intervention Disciform scar in 6 fellow eyes 0.108 0.139 0.068 following laser Abbreviation: PDT, photodynamic therapy. Note: *Student t-test. 778 Clinical Ophthalmology 2008:2(4)