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H. Ali, M. Khashba, S. Eissa, H. Elsaied
Cairo university, Faculty of medicine
Background and Aim: Nowadays, peribulbar block has been used as a tool in glaucoma surgery; it has a side effect of increased intra-ocular pressure that raises up the need of an adjuvant medication to overcome this problem in the diseased eye. Dexmedetomidine has been proved to decrease intraocular pressure (IOP) in the nonglaucomatous eye. In this triple blinded randomized study, Dexmedetomidine as an adjuvant to the peribulbar block, hypothetically, will decrease the intra-ocular pressure in the diseased eye.
Methods: 98 eyes were randomized to three groups D50 (35 eyes) with Dexmedetomidine 50 micrograms, D25 (33 eyes) Dexmedetomidine 25 micrograms or control group (C) (30 eyes) with plain peribulbar. The study was randomized triple-blinded aiming at testing the effect on intraocular pressure after the block injection.
Results: the IOP pre-injection was 27.71±2.52, 27.25±3.53, 26.2±3.57 mmHg in groups D50, D25 and C respectively in group D50 (p-value 0.058) then increased to 29.71±1.69, 30.25±2.36 and 29.4±3.756 in groups D50, D25 and C respectively with p-value >0.05.the pressure decreased after the surgery to 10.86±1.478in group D50, 10.75±1.63 in group D25 and 10.6±1.589 in C group with no statistical differences (p values were >0.05) among the groups.
Conclusions: Dexmedetomidine, as an additive to bupivacaine in the peribulbar block, has no effect on intraocular pressure. Moreover, it has no sedative effect on the patients. On the other hand, it prolongs the duration of the block and shortens the time to onset. It decreases the heart rate but without a clinical significant. This may be explained patient’s co-morbidity (such as hypertension that was treated with heart rate-controlling medications).
Dexmedetomidine as an additive to local anaesthesia to decrease intraocular pressure in glaucoma surgery
Characteristic
D50(n=35)
D25(n=33)
C(n=30)
P Value
Age (years)
56.14±7.923
54.25±5.23
55±6.47
0.537
Sex (M/F)
25/10
23/10
18/12
0.332
Patients height (cm)
165±7.9
167±8.3
170±6.3
0.368
Patients Weight(kg)
89±5.62
79±6.358
85±4.96
0.689
Patient status ASA (II/I)
30/5
29/4
27/3
0.716
Duration of surgery(min)
32.25±15
29.25±9.85
31.85±11.32
0.25
Type of surgery(SST/Valve)
25/10
22/11
21/9
0.900
Intra-ocular pressure(mmHg)
D50(n=35)
D25(n=33)
C(n=30)
P Value
Pre-injection
27.71±2.527
27.25±3.53
26.2±3.576
0.058
After injection
29.71±1.69
30.25±2.36
29.4±3.756
0.657
At the end of the surgery
10.86±1.478
10.75±1.63
10.6±1.589
0.502
Block dynamics
D50(n=35)
D25(n=33)
C(n=30)
P Value
Onset (min)
3.57±0.917
4.201±1.23
6±2.034
0.00*
Duration(min)
252.36±36.82
223.36±25.63
160±20.36
0.000*
D50(n=35)
D25(n=33)
C(n=30)
P Value
Heart rate(B/M)
65±2.416
70.36±4.325
79.5±4.798
0.031*
Mean arterial blood pressure(mmHg)
93.81±9.659
94.25±8.365
97±8.719
0.512
number of eyes assessed for eligibility101
98 cases randomized
35 cases in group D50
33 cases in group D25
30 cases in group C
3 refused to share
Table (4): hemodynamics (Data is presented as mean ±SD)* Statisticallysignificant compared to group (C), (p<0.05)
Figure (1): flow diagram
Table (1): Demographic and clinical characteristics. Data is presented as [(mean±SD)] or [No. (%)]
Table (2): Intra-ocular pressure through the procedure (Data is presented as mean ±SD)
Table (3): peribulbar block onset and duration (Data is presented as mean ±SD)* Statistically significant compared to group (C), (p<0.05)

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