Georgalas et al Table 2 Table demonstrating the time elapsed between combined vitrectomy–phacoemulsiﬁcation and posterior capsule opaciﬁcation Time until PCO ERM 10 5 6 9 11 12 5 8 11 8 14 18 6 9 11 12 19 6 MH 12 18 17 10 19 9 19 14 16 15 18 17 Case 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 136 Abbreviations: ERM, epiretinal membrane; MH, macular hole; PCO, posterior capsule opaciﬁcation. Note: Time until PCO is measured in months. as interleukin-1 (IL-1), IL-6, IL-8, basic ﬁbroblast growth factor and transforming growth factor. These cytokines may play an important role in ﬁbrous proliferation of LECs via an autocrine pathway, paracrine pathway, or both.14,15 The degree of postoperative inﬂammation appears to be related to PCO development after combined surgery even in patients without diabetes mellitus.11 Silicone IOLs have been considered to provoke PCO.16 Other factors that are considered to contribute to the for- mation of PCO include IOL decentration, capsulorhexis decentration, capsule tears, and insufﬁcient zonules, but in our cases we had none of these complications. In our study, where we chose an acrylic IOL, the capsular ﬁbrosis in the cases dealt with combined vitrectomy and phacoemulsiﬁcation was probably enhanced by accumulation of ﬁbrin and proliferation of stimulating factors in the space between IOL and the posterior capsule. In cases treated with combined surgery the posterior capsule is “supported” by ﬂuid or gas and not from the vitreous, as it happens in eyes undergoing cataract surgery alone; this may have a role in the induction of posterior capsular ﬁbrosis in the early post- operative period, and this ﬁnding is in accordance with the f indings of other authors.17,18 Another contributing factor to early occurrence of PCO after combined surgery, could be the inﬂammation which is induced by the prolonged surgery time and the combination of cataract with vitrectomy surgery. In addition, the appearance of signiﬁcant PCO seemed to have occurred earlier in the eyes that underwent com- bined surgery due to ERM (mean 10.0 months) compared to the patients having a MH preoperatively (15.33 months). Although it is difﬁcult to draw an accurate conclusion due to the small number of patients, it seems that the use of intravitreal gas which is used in all eyes undergoing MH surgery–but usually not in uncomplicated vitrectomy for ERM–does not enhance the occurrence of PCO. It is not unlikely that in cases with intravitreal gas use (MH cases), the gas “supports” the posterior capsule against the IOL and narrows the space between IOL and capsule forming a barrier to cell migration. On the other hand in cases with ERM the posterior capsule is loosely “supported” by the ﬂuid ﬁlling the vitreous cavity giving more space for cell migration between the IOL and the capsule. Additionally, the under- lying condition responsible for the occurrence of the ERM such as branch retinal vein occlusion, uveitis, or previous cryotherapy or laser may have played an additional role in the earlier occurrence of PCO in eyes with ERMs. Neodymium:YAG laser capsulotomy can cause short- and long-term IOP elevations that could possibly induce subsequent glaucoma and damage to the optic nerve.19 The underlying mechanism to this IOP rise after Nd:YAG laser capsulotomy remains unclear. Proposed mechanisms include effects to the ciliary body caused by the laser shock waves, a neurohumoral increase in the IOP, structural effects of laser energy on sodium hyaluronate, and ﬁnally mechanical block- age of the trabeculum with various debris such as fragments from the disrupted posterior capsule or vitreous. Other well established complications of Nd:YAG laser capsulotomy are retinal detachment and macular edema.20,21 Proposed mecha- nisms for the above complications include liquefaction of the vitreous and interruption of the anterior hyaloid face. In our study, no major complication was observed after the YAG capsulotomy apart from transient mild IOP spikes that were easily controlled with antiglaucoma drops. The absence of complications of YAG laser in the vitrectomized eyes of our study could be attributed to the absence of vitre- ous, alterations of which have been considered to play an important role in the development of IOP elevation, retinal detachment, and cystoid macular edema. Interestingly, IOL decentration or dislocation did not occur in any eye after YAG laser capsulotomy and the post-Nd:YAG capsulotomy visual acuity was restored in all 34 eyes. Therapeutics and Clinical Risk Management 2009:5