A pilot study of the precision of digital intraocular pressure measurement during vitrectomy

AIM:To evaluate the precision of digital intraocular pressure(IOP)measurement in silicone oil(SO)filled eyes during vitrectomy.METHODS:This is a retrospective,single-blind study.Patients who were diagnosed with retinal detachment and scheduled for vitrectomy with SO injection were consecutively enrolled.During the vitrectomy,IOP was digitally measured and then by a rebound tonometer(Icare PRO).The rebound tonometer readings were masked to the surgeons.The digitally measured IOP and that of rebound tonometer were compared,and the inter-methods agreement was assessed.The absolute deviation in IOP values between these two methods(△IOP)was also calculated,and correlations between△IOP and refractive status,lens status and levels of surgeons’experience were analyzed.RESULTS:A total of 131 patients(131 eyes)were recruited,with a mean age of 51.0±16.1 y.There was no significant difference in IOPs between digital measurement and the rebound tonometer(15.6±4.3 vs 15.7±5.1 mm Hg;t=0.406,P=0.686).Intraclass correlation coefficients(ICC)analysis indicated a strong correlation between these two measurements(ICC=0.830,P<0.001).The mean△IOP was 2.0±1.9 mm Hg(range:0-12.8 mm Hg),with 98 eyes(74.8%)had the△IOP within 3 mm Hg.△IOP was found to be negatively correlated with levels of surgeons’experience(r=-0.183;P=0.037),but not with the refractive status or lens status of the patients(both P>0.05).CONCLUSION:For experienced surgeons,the digital IOP measurement may be an acceptable technique for IOP measurement in SO filled eyes during vitrectomy.However,its use by inexperienced surgeons should be taken with caution.