Current status and future strategies of cytoreductive surgery plus intraperitoneal hyperthermic chemotherapy for peritoneal carcinomatosis

This article is to offer a concise review on the use of cytoreductive surgery （CRS） plus intraperitoneal hyperthermic chemotherapy （IPHC） for the treatment of peritoneal carcinomatosis （PC）. Traditionally, PC was treated with systemic chemotherapy alone with very poor response and a median survival of less than 6 too. With the establishment of several phase Ⅱ studies, a new trend has been developed toward the use of CRS plus IPHC as a standard method for treating selected patients with PC, in whom sufficient cytoreduction could be achieved. In spite of the need for more high quality phase Ⅲ studies, there is now a consensus among many surgical oncology experts throughout the world about the use of this new treatment strategy as standard care for colorectal cancer patients with PC. This review summarizes the current status and possible progress in future.

Effect of preoperative immunonutrition and other nutrition models on cellular immune parameters

AIM:To evaluate the effects of preoperative immunonutrition and other nutrition models on the cellular immunity parameters of patients with gastrointestinal tumors before surgical intervention.In addition,effects on postoperative complications were examined. METHODS:Patients with gastrointestinal tumors were randomized into 3 groups.The immunonutrition group received a combination of arginine,fatty acids and nucleotides.The second and third group received normal nutrition and standard enteral nutrition,respectively.Nutrition protocols were administered for 7 d prior to the operation.Nutritional parameters,in particular prealbumin levels and lymphocyte subpopulations(CD4+,CD8+,CD16+/56+,and CD69 cells)were evaluated before and after the nutrition protocols.Groups were compared in terms of postoperative complications and duration of hospital stay. RESULTS:Of the 42 patients who completed thestudy,16 received immunonutrition,13 received normal nutrition and 13 received standard enteral nutrition. prealbumin values were low in every group,but this parameter was improved after the nutritional protocol only in the immunonutrition group(13.64±8.83 vs 15.98±8.66,P=0.037).Groups were similar in terms of CD4+,CD16+/56,and CD69+prior to the nutritional protocol;whereas CD8+was higher in the standard nutrition group compared to the immunonutrition group.After nutritional protocols,none of the groups had an increase in their lymphocyte subpopulations.Also,groups did not differ in terms of postoperative complications and postoperative durations of hospital stay. CONCLUSION:Preoperative immunonutrition provided a significant increase in prealbumin levels,while it did not significantly alter T lymphocyte subpopulation counts,the rate of postoperative complications and the duration of hospital stay.

Multi-disciplinary treatment for cholangiocellular carcinoma

Cholangiocarcinoma(CC)is rare malignant tumors composed of cells that resemble those of the biliary tract.It is notoriously difficult to diagnose,and is associated with a high mortality.Traditionally,CC is divided into intrahepatic and extraheaptic disease according to its location within the biliary tree.Intrahepatic cholangiocellular carcinoma(IH-CCC)or peripheral cholangiocellular carcinoma(CCC)appears within the second bifurcation of hepatic bile duct,and is the second most common primary liver cancer following hepatocellular carcinoma(HCC),IH-CCC or peripheral CCC often presents with advanced clinical features,and the cause for this cancer rise is still unclear.MRI,CT and PET provide useful diagnostic information in those patients.Surgical resection is the only chance for cure,with results depending on selected patients and careful surgical technique.Liver transplantation could offer long-term survival in selected patients when combined with chemotherapy.Chemotherapy,radiation therapy or combination therapies remain as the only treatment for inoperable patients.However,these are uniformly ineffective in patients' survival.

Surgical management of gastric stump cancer:a report of 37 cases

Objective:To observe the clinicopathological characteristics of gastric stump cancer(GSC)and evaluate the benefitsof radical surgery of GSC.Methods:The clinicopathological characteristics and postoperative survival time of 37 GSC patientswho underwent surgery were investigated retrospectively.The survival time was compared according to the type of surgicaloperation(radical resection vs palliative operation).Twenty-one cases that received radical resection were analyzed based on thepTMN stage.Survival curves were traced by using Kaplan-Meier methods.Results:Most GSC(32/37)was detected in patientswho had received Billroth Ⅱ reconstruction after partial gastrectomy for benign gastric disease.The lesser curvature side and thesuture line of anastomosis were the most frequent sites where GSC occurred(27/37).Differentiated adenocarcinoma was thedominant histopathological type(24/37).The postoperative 5-year survival rate of early stage GSC patients(n=9)was significantlyhigher than advanced stage GSC(n=12)(55.6% vs 16.5%,x_L^2=11.48,P<0.01).Five-year survival rate of 21 GSC patients withradical resection were 75%(3/4)for stage Ⅰ,60%(3/5)for stage Ⅱ,14.2%(1/7)for stage Ⅲ,and 0%(0/5)for stage Ⅳ respectively.The median survival time of 21 GSC patients who underwent radical resection was longer than those undergoing palliative op-eration(43.0 m vs 13.0 m,X_L^2=36.31,P<0.01),the median survival time of stage Ⅳ patients with radical resection was 23.8months.Conclusions:Without remote metastasis,radical resection for GSC is possible,and is an effective way to improve theprognosis of GSC.Even in stage Ⅳ GSC,radical resection can still prolong the survival time.It is necessary for the patients withbenign gastric diseases who received partial gastrectomy to carry out the endoscopy follow-up,especially in patients with BillrothⅡ reconstruction procedure at 15-20 years.

Preoperative evaluation with T-staging system for hilar cholangiocarcinoma

AIM： To investigate the clinical value of T-staging system in the preoperative assessment of hilar cholangiocarcinoma. METHODS： From March 1993 to January 2006, 85 patients who had cholangiocarcinoma diagnosed by operative tissue-biopsy were placed into one of three stages based on the new T-staging system, and it was evaluated the resectability and survival correlated with T-staging. RESULTS： The likelihood of resection and achieving tumor-free margin decreased progressively with increasing T stage （P 〈 0.05）. The cumulative 1-year survival rates of T1, T2 and T3 patients were 71.8%, 50.8% and 12.9% respectively, and the cumulative 3-year survival rate was 34.4%, 18.2% and 0% respectively; the survival of different stage patients differed markedly （P 〈 0.001）. Median survival in the hepatic resection group was greater than in the group that did not undergo hepatic resection （28 mo vs 18 mo; P 〈 0.05）. The overall accuracy for combined MRCP and color Doppler Ultrasonagraphy detecting disease was higher than that of combined using CT and color Doppler Ultrasonagraphy （91.4% vs 68%; P 〈 0.05 ）. And it was also higher in detecting port vein involvement （90% vs 54.5%; P 〈 0.05）.CONCLUSION： The proposed staging system for hilar cholangiocarcinoma can accurately predict resectability, the likelihood of metastatic disease, and survival. A concomitant partial hepatectomy would help to attain curative resection and the possibility of longterm survival. MRCP/MRA coupled with color Doppler UItrasonagraphy was necessary for preoperative evaluation of hilar cholangiocarcinoma.（OR = 2.46, 95% CI = 0.98-6.14）, and a significantly elevated risk of developing esophageal cancer among alcohol drinkers among alcohol drinkers （OR = 9.86, 95% CI = 3.10-31.38）. CONCLUSION： ADH2 and ALDH2 genotypes areassociated with esophageal cancer risk. ADH2＊1 allele and ALDH2＊2 allele carriers have a much higher risk of developing esophageal cancer, especially among alcohol drinkers.

Antioxidant enriched enteral nutrition and oxidative stress after major gastrointestinal tract surgery

AIM: To investigate the effects of an enteral supple-ment containing antioxidants on circulating levels of antioxidants and indicators of oxidative stress after major gastrointestinal surgery.METHODS: Twenty-one patients undergoing major upper gastrointestinal tract surgery were randomised in a single centre, open label study on the effect of postoperative enteral nutrition supplementedwith antioxidants. The effect on circulating levels of antioxidants and indicators of oxidative stress, such as F2-isoprostane, was studied. RESULTS: The antioxidant enteral supplement showed no adverse effects and was well tolerated. After surgery a decrease in the circulating levels of antioxidant parameters was observed. Only selenium and glutamine levels were restored to pre-operative values one week after surgery. F2-isoprostane increased in the first three postoperative days only in the antioxidant supplemented group. Lipopolysaccharide binding protein (LBP) levels decreased faster in the antioxidant group after surgery.CONCLUSION: Despite lower antioxidant levels there was no increase in the circulating markers of oxidative stress on the first day after major abdominal surgery. The rise in F2-isoprostane in patients receiving the antioxidant supplement may be related to the conversion of antioxidants to oxidants which raises questions on antioxidant supplementation. Module AOX restored the postoperative decrease in selenium levels. The rapid decrease in LBP levels in the antioxidant group suggests a possible protective effect on gut wall integrity. Further studies are needed on the role of oxidative stress on outcome and the use of antioxidants in patients undergoing major abdominal surgery.

Continuous wound infusion of local anaesthetic agents following colorectal surgery:Systematic review and meta-analysis

AIM:To provide a specifi c review and meta-analysis of the available evidence for continuous wound infusion of local anaesthetic agents following midline laparoto-my for major colorectal surgery. METHODS: Medline, Embase, trial registries, conference proceedings and article reference lists were searched to identify randomised, controlled trials of continuous wound infusion of local anaesthetic agents following colorectal surgery. The primary outcomes were opioid consumption, pain visual analogue scores (VASs), return to bowel function and length of hospital stay. Weighted mean difference were calculated for continuous outcomes. RESULTS: Five trials containing 542 laparotomy wounds were eligible for inclusion. There was a sig- nificant decrease in post-operative pain VAS at rest on day 3 (weighted mean difference: -0.43; 95% CI: -0.81 to -0.04; P = 0.03) but not on post-operative day 1 and 2. Local anaesthetic infusion was associated with a signifi cant reduction in pain VAS on movement on all three post-operative days (day 1 weighted mean difference: -1.14; 95% CI: -2.24 to -0.041; P = 0.04, day 2 weighted mean difference: -0.97, 95% CI: -1.91to -0.029; P = 0.04, day 3 weighted mean difference: -0.61; 95% CI: 1.01 to -0.20; P = 0.0038). Local an- aesthetic wound infusion was associated with a signifi - cant decrease in total opioid consumption (weighted mean difference: -40.13; 95% CI: -76.74 to -3.53; P = 0.03). There was no signifi cant decrease in length of stay (weighted mean difference: -20.87; 95% CI: -46.96 to 5.21; P = 0.12) or return of bowel function (weighted mean difference: -9.40; 95% CI: -33.98 to 15.17; P = 0.45). CONCLUSION: The results of this systematic re- view and meta-analysis suggest that local anaesthetic wound infusion following laparotomy for major color- ectal surgery is a promising technique but do not pro- vide conclusive evidence of benefi t. Further research is required including cost-effectiveness analysis.

Hepatic non-parenchymal cells and extracellular matrix participate in oval cell-mediated liver regeneration

AIM： To elucidate the interaction between non- parenchymal cells, extracellular matrix and oval cells during the restituting process of liver injury induced by partial hepatectomy （PH）. METHODS： We examined the localization of oval cells, non-parenchymal cells, and the extracellular matrix components using immunohistochemical and double immunofluorescent analysis during the proliferation and differentiation of oval cells in N-2- acetylaminofluorene （2-AAF）/PH rat model. RESULTS： By day 2 after PH, small oval cells began to proliferate around the portal area. Most of stellate cells and laminin were present along the hepatic sinusoids in the periportal area. Kupffer cells and fibronectin markedly increased in the whole hepatic Iobule. From day 4 to 9, oval cells spread further into hepatic parenchyma, closely associated with stellate cells, fibronectin and laminin. Kupffer cells admixed with oval cells by day 6 and then decreased in the periportal zone. From day 12 to 15, most of hepatic stellate cells （HSCs）, laminin and fibronectin located around the small hepatocyte nodus, and minority of them appeared in the nodus. Kupffer cells were mainly limited in the pericentral sinusoids. After day 18, the normal liver Iobule structures began to recover.CONCLUSION： Local hepatic microenvironment may participate in the oval cell-mediated liver regeneration through the cell-cell and cell-matrix interactions.

Factors Influencing Pleural Effusion after Fontan Operation:an Analysis with 95 Patients

Objective To investigate the association between preoperative,operative,and postoperative factors and persistent pleural effusion after the extracardiac Fontan procedure. Methods Ninety-five consecutive patients diagnosed with univentricular heart underwent extracardiac connection using Gore-Tax conduits at the Department of Children’s Heart Centre,Justus-Liebig-University Giessen in Germany from June 1996 to July 2007. The outcome measures were duration and volume of chest tube drainage after surgical intervention. The investigated factors included age and weight at the time of operation,anatomical diagnosis,preoperative oxygen saturation,mean pulmonary artery pressure,ventricular end-diastolic pressure,fenestration,cardiopulmonary bypass time,conduit size,postoperative pulmonary artery pressure,administration of angiotensin-converting enzyme inhibitors,and postoperative infection. Associations between these factors and persistent pleural effusion after the extracardiac Fontan procedure were analyzed. Results Every patient suffered postoperative effusion. The median duration of postoperative chest tube drainage was 9 days (range,3-69 days),and the median volume was 12 mL·kg-1·d-1 (range,2.0-37.5 mL·kg-1·d-1). Thirty-seven (38.9%) patients had pleural drainage for more than 15 days,and the volume in 35 (36.8%) patients exceeded 25 mL·kg-1·d-1. Nineteen (20%) patients required placement of additional chest tubes for re-accumulation of pleural effusion after removal of previous chest tubes. Fifteen (17.8%) patients were hospitalized again due to pleural effusion after discharge. The median length of hospital stay after the operation was 14 days (range,4-78 days). Multivariate analysis results showed that non-fenestration,low preoperative oxygen saturation,and postoperative infections were independent risk factors for prolonged duration of pleural drainage (P<0.05). Long cardiopulmonary bypass time,non-fenestration,small conduit size,and low preoperative oxygen saturation were independent risk factors for excessive volume of pleural drainage (P<0.05).Conclusions For reduing postoperative duration and volume of pleural drainage following Fontan procedure,it seems to be important to improve the preoperative oxygen saturation,use large size of conduit,shorten cardiopulmonary bypass time,and make fenestration during the operation,as well as avoid postoperative infections.

An Overview of CyberKnife Radiosurgery

Stereotactic radiosurgery is a non-invasive procedure that utilizes precisely targeted radiation as an ablative surgical tool. Conventional radiosurgery devices, such as the Gamma Knife, rely upon skeletally attached Stereotactic frames to immobilize the patient and precisely determine the 3D spatial position of a tumor. A relatively new instrument, the CyberKnife (Accuray, Inc., Sunnyvale, CA), makes it possible to administer radiosurgery without a frame. The CyberKnife localizes clinical targets using a very accurate image-to-image correlation algorithm, and precisely cross-fires high-energy radiation from a lightweight linear accelerator by means of a highly manipulable robotic arm. CyberKnife radiosurgery is an effective alternative to conventional surgery or radiation therapy for a range of tumors and some non-neoplastic disorders. This report will describe CyberKnife technology and oncologic applications in neurosurgery and throughout the body.

Correction of hypovitaminosis D improved global longitudinal strain earlier than left ventricular ejection fraction in cardiovascular older adults after orthopaedic surgery

Background Cardiovascular diseases and insufficient levels of vitamin D are risk factors for adverse surgical outcomes, and they are both commonly present among older adults undergoing orthopaedic surgery. Giving the cardiovascular effects of vitamin D, pre-operative diagnosis of hypovitaminosis D would be a valuable step for the implementation of supplementation protocols. We investigated if the nor- malization of serum 25 [OH] D could ameliorate cardiac performance of older adults suffering from cardiovascular diseases. Methods We enrolled 47 older adults scheduled for major orthopaedic surgery and suffering from hypovitaminosis D. Patients underwent 6-months cal- cifediol supplementation with a starting dose at first post-operative day of 50 ~tg/die in liquid preparation. Down-titration to 20 Ixg/die at 3-months assessment was planned. Cardiac performance was evaluated by measuring left ventricular ejection fraction （LVEF） and global longitudinal strain （GLS） during pre-operative assessments and at 1-month, 3-months, 6-months follow-ups. Results Six months of cal- cifediol supplementation were associated with a significant improvement of both LVEF （＋ 3.94%; 95% CI： -4.0789 to -0.8232; P 〈 0.01） and GLS （＋ 18.56%; Z = -5.895; P 〈 0.0001）. Conclusions Calcifediol supplementation normalized serum 25 [OH] D concentration after 1-month treatment. GLS offered better insights into myocardial contractile amelioration than LVEF, thus being useful for detecting earlier subclinical changes that may anticipate hemodynamic modifications.

RESPONSE OF EARLY STAGE BULKY CERVICAL SQUAMOUS CARCINOMA TO PREOPERATIVE ADJUVANT CHEMOTHERAPY

Objective To investigate the potential role of preoperative adjuvant chemotherapy on early stage cervical squamous carcinoma with bulky tumor. Methods One hundred and forty-five patients with cervical squamous cancer stagesⅠb-Ⅱa were investigated, among which17 patients with bulky tumors (≥4 cm) were managed by cisplatin-based chemotherapy for 1-2 courses followed by radical hysterectomy and pelvic lymphadenectomy (BC group). The change of tumor size, pelvic lymph nodes metastasis, cervical wall invasion, the involvement of surgical specimen margin, and the blood loss during operation were assessed after opera-tion and compared with those in 51 patients with bulky tumors (BN group) and 77 patients with small local tumors (S group) who underwent surgery directly. Results (1) The tumor size of 17 patients in BC group were decreased in various degrees after chemotherapy, with 13 pati-ents of clinical effectiveness (76.47%). And the responsiveness pertained to neither histological differentiation nor size of local tumors. (2) Post-operative histology has showed that patients in BC and BN group have higher incidence of lymph node metastasis and deep cervical infiltration (5/68 and 3/68, respectively) than in S group (1/77 and 1/77, respectively) while with no statistical significance. (3) Blood loss during operation in BC group was less than BN and S group. (4) Seventeen patients, including those underwent surgeries of vaginal prolongation and/or ovarian transposition, appeared disease-free survival within the follow-up time. Conclusions Most of patients with bulky early stage cervical squamous carcinoma are sensitive to cisplatin-based chem-otherapy, which could greatly reduce local tumor size and in turn facilitate the following operation by well controlling blood loss.

Comparison of computed tomography and magnetic resonance imaging for the detection of mandibular condylar osteochondroma

Objective The purpose of this study was to compare computed tomography(CT) and magnetic resonance imaging(MRI) for the detection of mandibular condylar osteochondroma.Methods Preoperative CT and MRI of 33 patients with unilateral condylar osteochondroma were reviewed. The morphology, location, continuity with the parent bone, cartilage cap, perichondrium of tumors, and changes in soft and hard tissues adjacent to the lesions were investigated by two reviewers. Data were analyzed using Mc Nemar test. A P value < 0.05 was considered significant.Results Among the 33 condylar osteochondromas, 11 were of the diffuse type, 10 were of the sessile type, and 12 were of the pedunculated type. Continuity with the cortex and marrow of the host condyle was observed on both CT and MRI. Both modalities had identical detection rates of surface reconstruction of the temporal bone joint, condylar dislocation, and pseudarthrosis formation. However, MRI showed significantly higher detection rates of the cartilage cap and perichondrium than CT(P < 0.05). Furthermore, MRI showed ipsilateral and contralateral temporo-mandibular joint(TMJ) disc displacement in 4 cases and 6 cases, respectively, and ipsilateral and contralateral TMJ effusion in 20 cases and 14 cases, respectively.Conclusion CT can intuitively display the morphology and spatial location of condylar osteochondromas through three-dimensional reconstruction. MRI may be superior to CT in the detection of cartilage cap, perichondrium of the condylar osteochondroma, and changes in the TMJ and adjacent soft tissues.

Effect of preoperative limited fluid resuscitation to the patients with traumatic shock

Objective： To investigate the effect of preoperative limited fluid resuscitation on the patients with traumatic shock. Methods： Eighty-nine patients with multiple injuries complicating with shock were treated in Changhai Hospital Between January 2002 to October 2005 and were divided into 3 groups according to the preoperative levels of systolic blood pressure （SBP）. SBP of group A and group B were about 70 and 80 mmHg, respectively; and the SBP of group C was over 90 mmHg. Results, （1） There was no significant difference in age, gender, and injury severity score （ISS）, initiated resuscitation time and initiated operation time among the 3 groups. Preoperatively, there was significant difference in the amount of fluid resuscitation and infused erythrocyte suspension among group A, B and C （1687 ± 96 ml, 2096 ± 87 ml, 2976±93 ml, P〈0. 05; and 294±110 ml, 404±113 ml, 798±230 ml, P〈0. 05）. （2） The hemoglobin level in group C （94±45 g/L） was lower than that in group A （110±22 g/L） and group B （103±24 g/L） （P〈0.05）. However, there was no significant difference in the level of hemoglobin between group A and B. （3） There was no significant difference in the incidence of acute renal failure （ARF） among the 3 groups. The incidence of acute respiratory distress syndrome （ARDS） of group C （31.2%） was higher than that of group A （16.7%） and group B （18.2%） （P〈0.05）. The mortality of group C （34.4%） was higher than that of group A （12. 5% ） and group B （12. 1% ） （P〈0.05）. Conclusion： Preoperative limited resuscitation applied on patients with traumatic shock can reduce blood loss, incidence of ARDS and mortality.

Impact of homogeneous pathologic response to preoperative chemotherapy in patients with multiple colorectal liver metastases

AIM To analyze the homogeneity of pathologic response to preoperative chemotherapy(PRPC) after chemotherapy in patients with multiple liver metastases(LM).METHODS From September 2011 to August 2014,patients with at least two LM undergoing preoperative chemotherapy prior to resection were included in this retrospective,single-center study. The endpoints were PRPC homogeneity(according to both the Rubbia-Brandt and MD Anderson classifications),the impact of PRPC on the MDT decision,factors associated with homogeneous PRPC and overall survival of patients with vs. without homogeneous PRPC.RESULTS seventy-three patients with a total of 88 liver resections(including 15 two-stage procedures) were included in the study. The homogeneous PRPC rate was 55% according to the Rubbia-Brandt classification and 53% according to the MD Anderson classification. The MDT decision was modified by the PRPC in only 2.7% of patients(n = 2). CONCLUSION The PRPC was homogeneous in only one half of patients and had very little influence on the MDT decision.

Clinical Research of a Modified Midfacial Degloving in a Maxillectomy (with a Report of a Typical Case)

OBJECTIVE To investigate the feasibility of employing a modified midfacial degloving in maxillectomy. METHODS Eight patients with carcinoma of the maxillary sinus underwent a modified midfacial degloving operation. The tumors were classified according to the 2002 AJCC system. The TNM staging of the cases was as follows： 1 T4aN0M0, 2 T3N0M0 and 5 T2N0M0. Of the 8 cases, 1 patient underwent extended maxillectomy; exenteration of the orbit; tumorectomy of the sphenomaxillary and infratemporal fossae. Two patients received a total maxillectomy, and 5 a partial resection of the maxilla. Postoperative pathological report： 4 well-differentiated squamous carcinoma, 2 moderately-differentiated squamous carcinoma, 1 mucoepidermoid carcinoma and 1 adenoid cystic carcinoma.RESULTS A modified midfacial degloving operation can sufficiently expose a field of operation, resect the tumor within a safe margin, and leave no facial cicatricles. One patient died of intracranial metastasis 8 months after operation. We observed no recurrences or metastasis in other patients during the period of follow-up.CONCLUSION The major advantages of employing the modified midfacial degloving in maxillectomy is that a facial incision can be avoided. It has an advantage of minimal invasive surgery

About Laparoscopic Surgery Teaching Methods Discussed in this Paper

Surgery as one of the backbone of the clinical medical disciplines, it is a practical subject and the surgery teaching is an important component part of the surgery, is also a medical student to study the surgical aseptic technique and basic knowledge of the surgery and surgical basic skills, the students learned an important part of the theory is applied to clinical practice. Laparoscopy is a new technology, how to apply this new medical technology in surgery, to help students in the limited class hours quickly mastering their own knowledge, this is at present our country facing the most important subject in medical teaching. In view of the present of laparoscopic surgery in school teaching method were discussed and analyzed, and on how to have a purpose, systematic training students to master this skill, and to lay a good foundation of surgical basic skills of students, set up a bridge from slowly towards the classroom teaching of clinical practice.

The Application of PBL in Surgery Theory Teaching Research

objective： to study the problem oriented （PBL） teaching method application in surgery theory teaching effect. Methods： according to the student id number of single and double the surgical theory study stage of the 160 cases of medical students divided into two groups, the number into the control group （80 cases）, double number into the experimental group （80 cases）, traditional teaching method and PBL teaching method, respectively with the method of questionnaire survey to evaluate the two teaching methods. Results： after the introduction of PBL method in the experimental teaching, the students＇ classroom situation, knowledge situation, learning efficiency index score significantly higher than the control group, and the ability training all indicators were significantly higher than that of control group （P 〈 0.05）. Conclusion： the introduction of PBL in surgery theory teaching method, the feasibility of high, can provide a good decision for surgical theory teaching.

EFFECTS OF PREOPERATIVE SOFT CONTACT LENS WEAR ON HIGHER-ORDER ABERRATIONS AFTER LASER IN SITU KERATOMILEUSIS

Objective To evaluate the effects of preoperative soft contact lens (SCL) wear on higher-order aberrations(HOAs)correction after wavefront-guided and conventional laser in situ keratomileusis (LASIK). Methods A prospective randomized double-masked comparative study was conducted in 180 eyes of 90 patients scheduled for LASIK, including 92 eyes of 46 patients with previous SCL wear. The patients were divided into four groups: no SCL-conventional group, SCL-conventional group, no SCL-wavefront group and SCL-wavefront group. Preoperative and postoperative examinations included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), contrast sensitivity and HOAs. Results The UCVA and BSCVA were 20/20 in all patients at 6 months postoperatively. And 36.3%, 22.7%, 18.1% and 35.4% gained one line or more of BSCVA in no SCL-wavefront group, SCL-wavefront group, no SCL-conventional group and SCL-conventional group, respectively. Both the safety index and efficacy index surpassed one in 4 groups and were highest in no SCL-wavefront group. The increase in root-mean-square (RMS) values of HOAs was significantly lower in no SCL-wavefront group and higher in SCL-wavefront group. At 6 months postoperatively, the increase in RMS of HOAs (RMSh) were 0.67, 1.58, 1.17 and 1.28 in no SCL-wavefront group, SCL-wavefront group, no SCL-conventional group and SCL-conventional group, respectively. Conclusion Preoperative contact lens wear has significant influence on the efficacy of HOAs correction in wavefront-guided LASIK. Patients with contact lens wear preoperatively should be cautious when scheduled for wavefront-guided LASIK.