Bilal Khan, Asif Iqbal, Nuzhat Rahil, Muhammad Aetizaz, Mohammad Idris, Rahil Aumer Malik.
Effect of Yag Laser Energy in Mille Joules (Mj) for Change in IOP after Yag Laser Posterior Capsulotomy.
Ophthalmol Update Jan ;12(2):98-100.

Objectives: To determine the effect of YAG laser energy in Mj. for changes in intraocular pressure after YAG laser posterior capsulotomy. Material and Methods: This observational cross sectional study was conducted at outpatient department of Khyber Eye Foundation Gulbahar No 4 Peshawar from Jun 2011 to September 2012. In this study a total of 120 pseudophakic eyes were observed and assessed for the rise of IOP after different energy levels of a YAG laser capsulotomy carried out for secondary posterior capsular opacification that had developed after cataract surgery. Preoperative IOP was recorded. Then 2-3 mm size capsulotomy was done with Q-switched Nd: YAG Laser after topical anesthesia, by using 1.5 to 8mj of energy and fewest numbers of pulses. Patients were followed for assessment of IOP after one hour. The IOP and VA were checked on the 10th day again. Result: Out of 120 patients 71 (59.16%) were male and 49 (40.83%) were females. In this study 90 patients had normal or low IOP in whom Yag laser capsulotomy was done on less than 2.5mj .While 30 patients had rise of 2 ? 15 mm Hg in intraocular pressure after 3 mj of Yag laser .The rise noted when Yag laser was done on more than 3mj, the more the energy, the more rise in IOP observed. Discussion: The results of this study showed that frequency of ?raised IOP? was certainly associated with the high amount of laser energy delivered to the eyes and must be expected to be greater in patients who receive excessive amount of YAG laser energy. An IOP elevation of 10 mm Hg or more within two hours of laser surgery was seen in 15 eyes (4.4%) that had a capsulotomy. Though the mechanism(s) remained undetermined, the possible mechanisms would be: the more the energy used during the procedure, the more particles liberated from posterior capsular breakdown, resulted in the clogging of angle of anterior chamber and lead to the raised IOP. Additionally, the acoustic shock waves released inflammatory mediators that altered the trabecular meshwork and the aqueous dynamics and resulted in an IOP rise. Conclusion: Raised IOP was a frequent complication of Nd: YAG laser posterior capsulotomy. The higher the energy used, the greater the frequency of raised IOP following capsulotomy. Hence, it is recommended that each patient undergoing Nd: YAG laser capsulotomy should receive minimum possible laser energy and must be followed up for raised intraocular pressure.

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