Relationship between Amount of Energy Used and the Rise in Intraocular Pressure in Cases of YAG-Laser Posterior Capsulotomy

Objective: To find the relationship between the amount of laser energy used and the significant rise of intraocular pressure ( 5mmHg) in Nd-YAG laser posterior capsulotomy. Place and Duration: The study was conducted at eye department of Benazir Bhutto hospital, Rawalpindi, from September 2011 to April 2013. Materials and Methods: Ninety pseudophakic patients of adult age of either sex having posterior capsular opacification (PCO) and needing YAG capsulotomy were randomly enrolled for study. Intraocular pressure (IOP) just before the procedure and the amount of laser energy (m.joules) used in each case was recorded. Intraocular pressures were rechecked at 1hour, 4hours and 24 hours after the procedure. Total energy (in m.joules) used in each patient was grouped into i, low energy (up to 20mj) ii, intermediate (21 to 100mj) and iii, high energy ( 100mj) groups. Change of IOP at any of the three post laser recording times i.e. 1hour, 4hours and 24hours after the procedure was also categorized into i, no change, ii, a rise of 1-5mmHg and iii, a rise of more than 5mmHg (significant rise) . Results: A total of 90 patients, 42males and 48 females, age range 33-80 years were included in the study. Number of patients in low, intermediate and high laser energy groups was 6, 66 and 18 respectively and the significant rise in IOP was noted in 1/6 (16.6%), 19/66 (29%) and 9/18 (50%) of the patients in these groups, respectively. Significant rise of IOP after YAG laser capsulotomy was noted in 63.3% of the patients (19/30) at 1hour post laser application, while another 33.3% (10/30) and 3.3% (1/30) entered this category at 4 and 24 hours post laser application. Conclusion: There is a directly proportionate relationship between the amount of laser energy used and the post laser significant rise of IOP i.e. with higher energy use more chance of significant IOP rise. This IOP surge is noted within first four hours in 97% of patients in our study.