Intraocular pressure variations after diode laser photocoagulation for threshold retinopathy of prematurity

Purpose To investigate the intraocular pressure (IOP) variations occurring after indirect diode laser photocoagulation for threshold retinopathy of prematurity. Design Prospective, nonrandomized, comparative study. Participants A study group - 21 consecutive premature babies (42 eyes) undergoing diode laser photocoagulation for retinopathy of prematurity - and control groups - 32 premature babies (64 eyes) undergoing retinal examination with or without scleral indentation. Intervention Intraocular pressure was measured with a portable electronic tonometer before, immediately after, and 1, 2, and 3 days after diode laser photocoagulation in the study group; before retinal examination in control group 1; and before and after retinal examination with scleral indentation in control group 2. Main outcome measure Intraocular pressure after diode laser photocoagulation for threshold retinopathy of prematurity. Results Mean IOP in the study group rose from 15 mmHg (standard deviation [SD] = 4.1) before coagulation to 33.2 mmHg (SD = 7.8; range, 20-50) immediately after, and then dropped to 22.2 (SD = 5.2), 16.5 (SD = 3), and 14.5 mmHg (SD = 2.1) 1, 2, and 3 days later, respectively. All the changes were statistically significant at P<0.0001, except for the difference between days 2 and 3 (P = 0.096). Mean baseline IOPs were 16.3 mmHg (SD = 3.7) in control group 1 and 15.7 mmHg (SD = 2.3) in control group 2 (P = 0.84 between control group 1 and study group, and P = 0.32 between control group 2 and the study group). At termination of the retinal examination with scleral indentation (control group 2), IOP measured 15.1 mmHg (SD = 2.2) (P = 0.49 compared with baseline). Conclusions Intraocular pressure may be significantly elevated after diode laser photocoagulation for retinopathy of prematurity. The mechanism and long-term clinical implications of this observation should be investigated.