A Comparative Study Of "Double Bubble" DALK And PLP In The Treatment Of Advanced Keratoconus

Objective: To compare the clinical efficacy of penetrating keratoplasty(PKP)and modified "Big Bubble" technique—— "Double bubble" technique deep anterior lamellar keratoplasty(DALK)and "manual dissection" DALK in the treatment of advanced keratoconus(KC),including acute hydrops stage.Methods: A retrospective analysis was made of 47 patients(47 eyes)with advanced KC who underwent keratoplasty in XX Hospital from October 2007 to January 2018,including 21 eyes of PKP(10 eyes in acute hydrops stage and 11 eyes in stable stage),including 26 eyes of DALK(15 eyes in which a descemet membrane was exposed by "double bubble" technique during operation,and 11 eyes in which the technique of "double bubbles" failed to be used during the operation and Converted to "manual dissection",or a predescemetic plane was achieved by manual incision technique.The follow-up period was 1 year.Observation indexes included the best corrected visual acuity,corneal astigmatism,equivalent spherical,corneal endothelial cell density,intraoperative and postoperative complications and graft survival rate.Results: The average best corrected visual acuity(Log MAR)of 1,6 and 12 months after operation was0.32±0.19,0.27±0.16,0.20±0.11 in the PKP group and0.52±0.22,0.39±0.16,0.22±0.10 in the DALK group.There was significant difference between the two groups in 1 and 6 months(P < 0.005,0.002 and 0.019 respectively),and there was no significant difference between the two groups in 12 months(P > 0.05,0.52).One month after operation,the average BCVA of the four groups was significantly higher than that before operation(P =0.00).In the PKP group,the PKPa group was 0.36±0.22,0.29±0.17,0.20±0.12,and the PKPb group was0.29±0.16,0.26±0.15,0.20±0.11,respectively.There was no significant difference between the two groups(P>0.05,0.41,0.66,0.99respectively).DALKc group in DALK group was 0.45±0.20,0.33±0.15,0.18±0.08,DALKd group was0.63±0.21,0.46±0.16,0.27±0.11,respectively.There were significant differences between the two groups(P<0.005,0.037,0.042,0.021,respectively).Average astigmatism at 1,6 and 12 months after operation: PKP group was4.14±1.05,3.92±1.07,3.53±0.92,DALK group was 3.57±0.98,3.46±0.93,3.24±0.83,there was no significant difference between the two groups(P> 0.05,0.063,0.12,0.26respectively).There was no significant difference between the subgroups of PKP and DALK.The mean equivalent spherical at 1 and 12 months after operation were-2.92±1.37,-3.22±1.46 in the PKP group and-2.55±1.42,-2.43±1.44 in the DALK group,respectively.There was no significant difference between the two groups(P > 0.05,0.38,0.069 respectively),and there was no significant difference between the subgroups of the PKP and DALK groups.The average rate of endothelial cell loss was 7.89%±2.20%and 10.80%±3.19%in PKP group,and1.68%±1.90%and 1.87%±2.04%in DALK group at 6 and 12 months after operation,respectively.There was significant difference between the two groups(P =0.00).There was no significant difference between the subgroups of PKP and DALK.In terms of intraoperative and postoperative complications,there were no intraoperative complications in PKP group and 7.7% in DALK group.The intraoperative complications in DALK group were microperforation of Descemet's membrane.The incidence of secondary intraocular hypertension after operation was 42.9% in PKP group and 14.3% in DALK group.There was significant difference between the two groups(P < 0.05,0.014).The incidence of secondary glaucoma after operation was 11.5% in PKP group and 3.8% in DALK group.There was no significant difference between the two groups(P>0.05,0.2).The incidence of transplant rejection was 23.8% in PKP group and 3.8% in DALK group,with significant difference between the two groups(P < 0.05,0.041).Some complications were not statistically analyzed because of their specificity or scarcity of data.At the end of the last follow-up,there was no transplant failure,and the survival rates of both groups were 100%.No recurrence of the original disease was found in all patients.Conclusion: Both PKP and DALK are safe and effective for the treatment of advanced KC,and their visual enhancement effects are similar.modified "Big Bubble" technique—— "Double bubble" technique DALK treatment of KC is safe and effective.The acute hydrops stage of KC is not a contraindication for keratoplasty.