Techniques of Phacoemulsification

Techniques of Phacoemulsification Phacoemulsification is the preferred mode of cataract surgery today and considered better than other modes because of the lesser surgical time, better post-operative results, lower induced astigmatism and speedy visual rehabilitation. Cornea is a transparent structure and maintenance of transparency is attributed to the barrier function and the active fluid pump of the corneal endothelium. Endothelial damage during surgery is considered as a important parameters of surgical trauma. Endothelial cell density decreases at a greater rate after cataract surgery than it does in healthy, unoperated corneas. Corneal endothelial cells are non-dividing cells; hence having limiting regenerative capacity following surgical trauma. Corneal endothelial cell loss during surgery is affected by multiple variables like irrigation solution turbulence, direct mechanical trauma by instrument, nuclear fragments, IOL contact; heat generated during phacoemulsification can damage corneal endothelium during cataract surgery. In a study done by Hayashi K et al in 1996 they tried to identify the risk factors for corneal endothelial injury. They concluded in this study that older age, small pupil diameter, high nucleus grade, large nucleus, greater infusion volume, type of IOL implanted, and a greater amount of ultrasound energy used during surgery were associated with endothelial cell loss. Further studies carried out to identify variables affecting amount of endothelial cell loss which are related to various parameter of machine as well as technique of surgery. These variables also included medicinal substance used during surgery like irrigating fluid, type of viscoelastic substance used. Most of the studies indicated that endothelial cell loss is related to the more ultrasound energy used, amount of irrigating fluid or mechanical trauma by any mean. Site of incision, type of viscoelastic and irrigating fluid has less correlation with amount of endothelial cell loss. Though in special circumstances modification of these variables helps in getting better outcome of surgery. If we talk about the technique of phacoemulsification there are various nucleotomy techniques which are described. Every technique is unique in its application so it has an impact on amount of endothelial cell loss occurred due to surgical trauma. In this study we interpreted the effect of two types of nucleotomy techniques divide and conquer versus direct chop on endothelial cell loss. 60 eyes of 60 patients who underwent cataract surgery by these two different techniques were included in the study and amount of endothelial cell loss was measured and compared in two groups. All surgeries were performed by same surgeon and all other parameter and variables were kept constant like grade of nuclear sclerosis, type of machine used, type of irrigating fluid, viscoelastic and type of posterior chamber intraocular lens implanted. Study subjects were divided into two groups, Group1 included the patients who underwent phacoemulsification by divide and conquer technique and Group 2 included patient who underwent phacoemulsification by diect chop technique. The mean age of patients in group1 was 62.13 + 7.03 (SD) years and in group 2 was 61.77 + 8.37 (SD) years . The grade of nuclear sclerosis, graded by comparing with LOCS III chart was Grade 2 in all 60 eyes of the 60 enrolled patients. In group 1, 17 were male and 13 were females 18 were RE and 12 were LE. The median pre-operative specular count in this group was 2091 cells/mm2 with a mean specular count of cells/mm2(SD ). In group 2, 18 were male and 12 were females 16 were RE and 14 were LE. The median pre-operative specular count in this group was 2037 cells/mm2 with a mean specular count of cells/mm2(SD ). The intra-operative parameters assessed in thus study were two, the fluid volume used and the effective phaco time. In group 1 the average fluid volume used was 145.67 mL (SD 16.34 ). The average Effective phaco time was 14.70 sec (SD 2.77). In group 2 the average fluid volume used was 137.33 mL (SD 10.80). The average Effective phaco time was 12.67 sec (SD 2.34) Corneal endothelial cell counts were evaluated at 1 week, 4 weeks and 12 weeks post-operatively in both groups. Endothelial cell loss was calculated in this series as the difference between the pre-operative specular count and the specular count at 12 weeks. Further, the Endothelial cell loss (%) was calculated as: ECL (%) = Pre-op specular count-Post op count at 12 weeks x 100 Pre-op specular count The mean endothelial cell loss in group1 was 489 cells/mm2(SD 133.44).. The average endothelial cell loss (%) in group1 was 21.5%. The mean endothelial cell loss in group1 was 489 cells/mm2(SD 133.44).. The average endothelial cell loss (%) in group1 was 21.5%. The endothelial cell loss was analyzed statistically and its correlation to, effective phaco time and fluid volume was studied. In this study, the follow-up period was 3 months because Beltrame et al52 and other workers53, 54 have determined that a 3-month period was sufficient to allow stable and complete endothelial wound healing. In this study, the variables were analyzed with respect to their effect on the outcome using appropriate tests for statistical significance (SPSS17.0).Effective phaco time and fluid volume used showed a strong positive correlation to the endothelial cell loss (p-value