A Clinical Report On The Use Of Brust Mode Phacoemulsification And Continuous Mode Phacoemulsification

Nowadays ultrasound phacoemulsification has become the main choice in cataract surgery,however the application of ultrasound is associated with many problems such as incision burns, corneal edema, macula edema,etc.Many methods have evolved in recent years to enhance the efficacy of nuclear management during phacoemulsification including the new nucleotomy techniques(Divid and Conquer,In situ fracture technique,Chip and flip,Crack and flip,Stop and Chop )and the changing of ultrasound power released(pulse,burst) .The main purpose of all these techniques is to decrease the use of ultrasound power in nuclear emulsification and reduces surgical time, limiting endothelial damage.Objective: To compare the postoperative visual acuity and intraocular tissue injury of the patients underwent continuous mode and burst mode phacoemulcification,and to investigate the clinical indications.Methods: The senile cataract patients admitted into 2nd hospital of Jilin university during October 2005 to June 2006 were enrolled.The patients with eye or systemic diseases which would affect corneal endothelial cells or visual acuity were removed.The patients were randomly divided into 2 groups:A group continuous mode (194 eyes);B group burst mode (221 eyes).Each group was divided into 3 subgroups according to Emergy nuclear hardness, subgroup 1 has nuclear hardness of II,subgroup 2 is III and subgroup 3 as IV,which is called groupA1/B1,A2/B2,A3/B3. The mean ultrasound energy,accurate ultrasound time and accumulated ultrasound energy was recorded.The best visual acuity was measured at 1st,3rd,7th postoperative day,and so was the central corneal thickness at the 1st postoperative day,the central corneal endothelial cell density at 1st postoperative week and 1st ,3rd postoperative month,and the presence of anterior chamber flare and complications during the follow-up.Results: The best corrected visual acuity distribution of patients of A1 andB1 was not significantly different (P>0.05) at the 1st day,yet there was significant difference in A2/B2,A3/B3(P<0.05), and the best corrected visual acuity in burst mode group is higher. The difference of best corrected visual acuity distribution of patients of A1/B1,A2/B2 at the 3rd day were not statistically significant (P>0.05),however the A3/B3 group was different(P<0.05).The distribution of visual acuity between 0.9-1.0 of B1 group (55.32%) was slightly higher than A1 group(36.73%),although the difference was not significant (P>0.05);while the distribution in B2 and B3 subgroups (31.92%,10.91%) were higher than A2 and A3(12.24%,8.51%),and the differences were significant(P<0.05);The visual acuity of burst mode is better than continuous mode. At the 7th day,the best corrected visual acuity distribution of A1/B1,A2/B2 and A3/B3 were not different. The distribution of visual acuity of B1 and B2 between 0.9-1.0 (85.11%,58.8%) is slightly higher than A1 and A2(77.55%,43.9%),no significant difference yet; but the visual acuity distribution of B3 subgroup between 0.9-1.0 is 60.0% higher than continuous mode 31.9%,and the difference is significant(P<0.05).The accurate ultrasound time and accumulated ultrasound energy in burst mode group is significantly lower than continuous mode group(P<0.05).Thickness of central cornea of A1/B1,A2/B2,A3/B3 is increased at the 1st postoperative day,and the differences were significant (P<0.05).Morever,when compared with the corneal thickness of continous mode group ,the burst mode group is significantly lower(P<0.05).The corneal endothelial cell:the central corneal endothelial cell density of each subgroup at the 1st postoperative month is lower than it before, no difference between A1 and B1,but between A2 and B2, A3 and B3,it were statistically different(P<0.05).And the result at 3rd postoperative month is the same.The endothelial cell was continuously slightly losing in every subgroups after the surgery,but no statistical significance between the 1st month and the 3rdmonth(P>0.05).All operations were successful.No complications such as rupture of posterior capsule, hyphema occured in every subgroup during the operations;and no complications were seen after the operations for instance: the retinal detachment, macula edema and so on.Conclusions: Using burst mode during phacoemulcification can reduce the ultrasound energy,shorten the operation time, decrease the damage to corneal endothelial cell and rise the postoperative visual acuity.