1. The Efficacy and Safety of the Low Intensity Ultrasound Treatment in Patients with Open Angle Glaucoma
Hyoung Won Bae, Gong Je Seong, Chan Yun Kim
Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea
[ contact:
Disclosure: None
Purpose
The low intensity ultrasound (LIUS) is an ultrasonic wave used at an intensity of 1w/cm2, 1MHz, and 20 minutes/day or less. This study is to evaluate the intra-ocular pressure (IOP)-lowering effects and safety of the LIUS treatment in patients with primary open-angle glaucoma (POAG).
Results
Total 13 eyes of 13 patients with mean age (15.40) years were randomized to the LIUS - sham (n=7) or the sham – LIUS (n=6) sequence. Two groups did not differ at baseline in age, sex, visual field mean deviation, IOP, systolic and diastolic blood pressure, and body temperature (Table 1).
Methods
This prospective, randomized, double-blind, sham controlled, crossover clinical pilot study was performed at the glaucoma clinic of the Severance Hospital, Seoul, Korea between January 29, 2015 and January 5, The study was conducted in accordance with the Declaration of Helsinki, and informed written consent was obtained from each participant. The Institutional Review Board of the Yonsei University Health System approved the study protocol.
Thirteen blind eyes of 13 patients with POAG were finally enrolled in this study. The patients were instructed to discontinue their glaucoma medications for up to 6 weeks depending on the type of anti-glaucoma medication they were using. After washout period, they were randomized into one of the two crossover sequences of treatment for one week with LIUS or sham and subsequently crossed over to the alternative treatment for one week. Two 1-week phases of treatment were separated by a washout period of 3 weeks. LIUS was performed using an ultrasound machine that we developed (Figure 1). LIUS was done two times at an interval of 3 days at a strength of 240mW, for 10 minutes (Figure 2, 3). The effect of treatment on IOP was assessed using a linear mixed model.
Table 1. Baseline characteristics of the study participants.
Total (n=13)
LIUS  Sham (n = 7)
Sham  LIUS (n = 6)
p value
Age (year)
64.07±15.40
61.57±15.67
67.00±15.99
0.551
Sex (N, male/female)
9/4
5/2
4/2
1.000
Visual field MD (dB)
-31.90±0.85
-31.99±0.77
-31.78±1.01
0.666
IOP (mmHg)
32.31±10.61
32.00±13.08
32.67±8.04
0.916
CCT (µm)
526.0±23.5
530.0±25.0
520.5±22.5
0.454
Systolic BP (mmHg)
127.6±15.5
124.0±15.8
131.8±15.4
0.387
Diastolic BP (mmHg)
70.7±9.0
70.7±9.3
70.8±9.4
0.982
Heart rate (bpm)
76.0±9.9
77.3±10.4
74.5±10.0
0.633
Body temperature (°C)
36.3±0.3
36.3±0.2
0.938
In Table 2 and Figure 4, there was a significant long term effect of LIUS on decreasing IOP (p value=0.002). An increase of IOP 2.94 mmHg in the sham-treated group was found while a decrease of IOP 4.35 mmHg was found in the LIUS-treated group. The changes of IOP on 9 AM and 11 AM also showed the significant long term effects of LIUS (p value=0.008 and 0.032, respectively). However, there was no significant short term IOP-lowering effect of LIUS (p value=0.333). No adverse event was reported.
Figure 1. Ultrasound machine. a, ultrasonic transducer connection terminal; b, touch screen; c, power switch; d, power cable connection terminal; f, ultrasonic transducer connector; g, ultrasonic transducer.
Table 2. The effect of LIUS on IOP using a linear mixed model.
 Variable
Sham-treated
LIUS-treated
Difference (Sham-LIUS)
p value
Last IOP – Baseline IOP
-2.94 (-6.54, 0.66)
4.35 (0.72, 7.97)
-7.29 (-11.20, -3.37)
0.002
11AM IOP – 9AM IOP on same day
-0.60 (-1.25, 0.06)
0.96 (0.30, 1.62)
-1.56 (-2.28, -0.84)
0.333
3rd IOP – 1st IOP on 9 AM
-2.06 (-5.78, 1.67)
3.80 (0.05, 7.55)
-5.85 (-9.76, -1.95)
0.008
3rd IOP – 1st IOP on 11 AM
-2.64 (-7.00, 1.71)
2.73 (-1.65, 7.11)
-5.37 (-10.18, -0.56)
0.032
Figure 4. The graphs showing the IOP-lowering effect of LIUS.
Figure 2. A patient applying LIUS treatment.
Figure 3. Patients’ enrollment flowchart.
Conclusion
The LIUS seems to be an effective and safe way to reduce IOP in patients with open-angle glaucoma. Although additional large-scale clinical trials are needed, LIUS is expected as a new treatment for glaucoma.
No author has any conflicts of interest, financial or otherwise.