Vitrectomy with air tamponade for surgical repair of rhegmatogenous retinal detachment by eye position guided fluid-air exchange

AIM:To observe the efficacy and safety of pars plana vitrectomy(PPV)with eye position guided fluid-air exchange(FAX)and air to mponade in the treatment of rhegmatogenous retinal detachment(RRD).METHODS:RRD patients without severe proliferative vitreoretinopathy(PVR)C1 or more were enrolled.All patients underwent PPV combining with air tamponade.During operation,the primary retinal break(s)were placed at lower site and subretinal fluid was aspirated through the break(s)at the same time when eye position guided FAX was proceeding.Sufficient laser spots were made to seal the retinal break(s)after FAX,and filtered air was left in vitreous cavity as to mponade agent finally.The main outcomes were primary and final success rates,best corrected visual acuity(BCVA),and the secondary outcomes were rate of postoperative cataract surgery and high intraocular pressure.RESULTS:A total of 37 eyes(20 males and 17 females)with a follow-up time of≥6 mo were included.The range of RRD was 5.6±1.8 h,and the number of retinal breaks was 1.9±1.2.The breaks located at inferior quadrants(between 3:00 and 9:00)in 5 cases(13.5%),and both superior and inferior breaks were found in 3 cases(8.1%).A total of 25 cases(67.6%)with macular detached involvement,9 cases(24.3%)with intraocular lens,and 8 patients(21.6%)were treated with phacoemulsification and intraocular lens implantation together.The success rate of primary retinal reattachment was 100%(37/37).At 6 mo postoperatively,BCVA(logMAR)was increased from 1.13±1.07 to 0.23±0.15(P<0.001).Phacoemulsification combined with intraocular lens implantation was performed in 2 patients(5.4%),and one of them underwent macular epiretinal membrane peeling in addition(2.7%).Furthermore,high intraocular pressure was found in 4 cases(10.8%).CONCLUSION:PPV with air tamponade by eye position guided FAX can achieve a high reattachment success rate in the management of patients with RRD,and it has the advantages of short postoperative prone time and fewer operative complications.

MODELLING THE POLYALANINE BACKBONE STARTING FROM ALPHA-CARBON GUIDE POSITIONS

An automatic procedure for building a protein polyalanine backbone from guiding alpha-carbon positions is presented here,which is different from a previously developed'spare parts'approach(Jones and Thirup,1986;Claessens et al.,1989). In our procedure,the geometric restraint of angle N-CA-C is used to generate a list of polypeptide chains,and several filters are used later to select the best conformer.The most important filter is based upon the Ramachandran scatter plot of mainchain dihedral angles PHI and PSI.Results for all test cases are satisfactory,with more than 95%of peptide planes correctly reconstructed and the overall root-mean-square deviation less than 0.5 angstrom compared with the refined X-ray coordinates.