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Purpose:To study factors affecting laser energy levels required for neodymium: yttrium aluminium garnet (Nd: YAG) laser capsulotomy and to evaluate whether any correlation exists between applied laser energy levels and complications.Methods:The present study examined 474 consecutive patients for a number of factors including age, type of posterior capsule opacification (PCO), material and fixation of intraocular lens (IOL) and complication rates, versus energy levels used for Nd: YAG laser capsulotomy.Results:Mean patient age was 55.6 ± 8.7 years and mean follow up period was 22.9 ± 4.5 months. IOL biomaterial (KW ANOVA; P = 0.173) and patient's age (P = 0.246) did not significantly influence total laser energy requirement for capsulotomy. However, total laser energy levels were significantly higher (KW ANOVA; P < 0.001) with fibro-membranous and fibrous subtypes of PCO. Complications such as IOL pitting, intraocular pressure (IOP) elevation, uveitis, retinal detachment (RD) and cystoid macular edema (CME) were significantly more common when higher energy levels was used. The mean total energy in patients with RD was 77.7 ± 17.7 mJ as compared to 43.4 ± 26.9 mJ in the rest of the cohort. RD was more common in patients with higher axial length [n = 7 (63%)] (P < 0.001).Conclusion:Type of PCO significantly influenced laser energy levels required for capsulotomy, whereas IOL biomaterial and fixation did not. Complications such as IOL pitting, uveitis, IOP elevation, RD and CME was significantly more common when total laser energy was higher. It is recommended that the lowest possible single pulse laser energy be used for capsulotomy to minimize complications.