STUDY OF CUMULATIVE DISSIPATED ENERGY USING VARIOUS PHACO TIPS IN PHACOEMULSIFICATION SURGERY OF CATARACT- A PROSPECTIVE RANDOMIZED INTERVENTIONAL STUDY

Abstract

Background: Phacoemulsification surgery is being increasingly used as a method of choice in developing countries for cataract. It can be done by different methods viz. phaco chop technique and divide and conquer technique.  Cumulative dissipated energy (CDE) is used to monitor the energy delivered during the process of cataract surgery by phacoemulsification process. The less is the CDE, better is the corneal impact. Different phaco tips used in phacoemulsification are in the range of 0 to 45 degree as 0,15,30,45. We conducted a prospective interventional study to evaluate effectiveness of different phaco tips in various grades of cataract and its impact on cornea, effective phaco time and intraoperative complications in cataract surgery.

Patients and methods: This was a prospective interventional study in patients with age related cataract visiting a tertiary care hospital during a period of 1year. Patients aging more than 40 years having cataract were randomly divided in three groups. Group A (n=72), Group B (n=72) and Group C (n=72). Group A was operated using 0 degree phaco tip, Group B using 30 degree phaco tip and Group C using 45 degree phaco tip. Intraoperative effective phaco time (EPT), cumulative dissipated energy (CDE) and complications were noted in each group. Postoperatively patients were examined on Day 1, Day 7, Day 30, Day 45 and 6 months for best corrected visual acuity and status of cornea.

Results: 216 patients were included in the study which were randomly allocated Group A (n=72), Group B (n=72) and Group C (n=72). All the three groups were comparable with respect to age and gender (z= 0, p> 0.05). Mean EPT for 0 degree Phaco tip was 41.08 ± 9.3 sec, for 30 degrees was 43.38 ± 13.76 sec and for 45 degrees was 54.80 ± 19.83 sec. There was no statistically significant difference in the mean EPT of the patient who underwent phaco surgery using 0 and 30 degree phaco tips (z test= 1.42 and p value = 0.11.), however there was a statistically significantly difference in mean EPT, for 30 and 45 degrees (z test= 5.2 and p value =0.02.) and 0 and 45 degree phaco tips (z test= 9.2 and p value = 0.02). Mean CDE comparison between 0 and 30 degree tips was not statistically significant, however there was a statistically significantly difference in mean CDE, for 30 and 45 degrees (z test= 4.28 and p value = 0.01) and 0 and 45 degree phaco tips (z test=8.71, p value>0.01) operated patients of cataract. Most common intra operative complication was posterior capsular rent seen in 2.7 % of 0 degree phaco tip while 5.5% of 30 degrees and 5.5% of 45 degrees. Post operatively on Day 7, visual outcome depending on logMAR scale > 1 was41.6% in group A and 50% in group B (z= 1.98, p< 0.05). Similarly, on Day 7, clear cornea was seen in 61.1% group A and 33.3% in group B (z=2.0, p< 0.05).

Conclusions: We concluded that 0 degree tip was having similar visual outcome as 30 degree while both 0 and 30 degree had better visual outcome than 45 degree however and no difference was found in final best corrected visual acuity between 0, 30 and 45 degree phaco tip. It was also observed that 0-degree phaco tip was associated with decreased corneal damage as compared to 30 degree phaco tip and 30 degree with decreased damage than 45 degree phaco tip however, it did not affect final visual outcome.   0, 30 and 45 degree phaco tip was associated with same incidence of post-operative complication and it did not affect visual outcome. Also, Effective phaco time and Cumulative dissipated energy was similar in 0 degree tip compared to 30 degree tip and less in 30 than 45 degree phaco tip.

Keywords: BCVA (Best corrected visual acuity), EPT (Effective phaco time), NS(Nuclear sclerosis) , DM(Descemet’s membrane)