A Study On The Corneal Endothelial Lesion During Cold Phacoemulsification

AbstractThe main and ordinary complication related to phacoemulsification is the corneal endothelial cell lesion. It is believed that the primary factors are heat buildup and huge waves during phaco chipping to section the nucleus into debris of lens nucleus. To reduce the corneal endothelial cell injury, the term "cold phaco" that adopts low phaco energy and high vaccum technology is used. On the basis of this fact, it is of practical significance to study trauma to corneal endothelial cell during cold phaco, and it gives many advantages such as to choose a good operation method and to evaluate the effect of operation.In this study, the cases with different nucleus hardness are observed during cold and hot phaco. The corneal transparency, anterior chamber reaction, and specular microscopy are examined postopratively.Clinical study: Phacoemulsification was performed on 180 eyes with senile cataracts which were divided into three groups A, B, C on the nucleus hardness, 60 eyes in each, group A for less than grade II , group B for between II and â…¢ , group C for over â…£. In each group, the patients were again divided into 2 subgroups for cold and hot phaco, group A₁, B₁, C₁ for cold phaco (experiment group) ,group A₂,B₂,C₂ for hot phaco (control group). Preoperatively and in scheduling times postoperatively, the visual acuities, the cornea and anterior chamber reaction and specular microscopy were observed.Results1. Visual acuities: Postoperatively, the uncorrected visual acuities at 24hours were 0. 5 or better in 29 eyes (96. 7% ) in group A,, 28 eyes (93. 3% ) in group A2, 29 eyes (96.7%) in group B, ,7 eyes (2.33%) in groupB2,20 eyes (66. 7% ) in group C;,5 eyes ( 1. 67% ) in group C2. At 1 week, they were 0.5 or better in 29 eyes (96. 7% ) in group A,, 29 eyes (96. 7% ) in group A2,30 eyes (100%) in group BM28 eyes (93.3%) in group B2, 29 eyes (96. 7% ) in group Cj ,9 eyes (3. 0% ) in group C2.2. Corneal endothelium: Postoperatively, the corneas remained transparent within 2 hours. At 6 hours, corneal edema was observed and was marked at 48 hours. The muddy posterior limiting lamina was seen in 20 percent of patients in group Cj, all patients in group B2and most patients in group C2. Corneal edemas subsided generally with time after 48 hours.3. Anterior chamber reaction;The inflammation changes were found only in group C2.4. Specula microscopy: (1) The morphology of endothelium of corneas;The endothelial cells were hexagonal and similar in size. The border of cells was clear and cell junction was tight. Postoperatively, the area of cells was altered at 0 hours. Endothelial cell counts of triangle and pentagon increased. At 6 hours, obvious changes were seen and became more serious with time. Marked swelling and degeneration of endothelium was revealed and black zones were found. The size was different and the shape was irregular. The normal hexagon was disappeared. The cell around black zone was enlarged and loosened. The normal appearance of endothelium was restored partly and marked sign of migration of the cornel endothelium was displayed 24 hours following operation. The appearance in group A,, Bj, Cx, A2was returned to normal, month after operation. (2) Corneal endothelial cell quantitative analysis preoperatively and postoperatively: (l)The endothelial cell density was decreased since 6 hours after operation, significant difference was found between preoperation and same points of time between different group after operation(P <0. 01). At 1 week and 1 month, it was not different between group Al and group A2( P >0. 05) ,but it was different between group Bj and group B2(P <0.05) ,significant between group Ct and group C2(P <0.01). ?The proportions of hexagonal cell were decreased postoperatively. It was not different except between group Cj and group C2. (3)The pro-portions of corneal endothelial cell loss;At 1 week, it was 5. 17 ±0. 77% in group A,, 5.53 ±0.52% in B,, 10.41 ±1.42% in group C,, 5.73 ±0.61% in group A2, 8. 20 ± 1. 26% in group B2, 14. 53 ± 2. 93% in group C2. At 1 month, the proportions were 5. 59 ±0.75% , 6. 39 ± 0. 69% , 11.04 ±1.83% , 6. 06 ±0.84%, 12.81 ±2.06%, 16.17 ±3.50%, in group A,, B,, C,, A2, B2, C2, respectively. It was not different between group A, and group A2(P> 0. 05) , but obvious different between group Bj and group B2 ( P < 0. 05 ), marked different between group Cx and group C2(P<0.01).Conclusion1. There was no difference in corneal endothelial cell lesion to cataract patients with less than grade II nucleus hardness between hot phaco and cold phaco, but significant to patients with below grade IV nucleus hardness.2. Corneal endothelial cell loss is very less in patient of below grade IV nucleus hardness. Corneal endothelial cell loss of cold phacoemulsification is not change by valid time of changed, but the structure changes of corneal endothelial cell directly related to the valid phaco time.3. By comparison with hot phaco, cold phaco are considered to be safe and the structure of corneal endothelial cell was restored fastly after operation for the patients with over grade IV nucleus hardness.4. Much less the corneal endothelial cell lesion was found during cold phacoemulsification and aspiration,compared with hot phaco. Generally, cell lesion was restored faster and was reversible.As a result, cold phaco may reduce trauma to the corneal endothelium, raise safety of operation and be applicable to all kinds of cases.