Soft contact lens-induced corneal deformation in the posterior corneal surface

OBJECTIVE

This case report aims to highlight the corneal deformation induced by soft contact lens (SCL) wear, which is accompanied by changes in not only the anterior but also the posterior surface of cornea.

CASE REPORT

Cases are presented of two patients who wore non- planned replacement SCL for more than 15 years fabricated from materials with low oxygen permeability, sought a consultation with complaints of visual acuity loss in the both eyes. Anterior segment optical coherence tomography imaging demonstrated corneal deformation in the posterior as well as the anterior surface in both eyes of two patients, resulting in the diagnosis of corneal deformation induced by SCL wear. After the cessation of lens wear, there were improvements in visual acuity, anterior and posterior corneal higher-order aberrations, and changes in the anterior corneal shape, whereas the posterior corneal shape was improved in one case and remained mildly deformed in the other case.

CONCLUSION

Wearing SCLs with low oxygen permeability for long time periods, could induce corneal deformation in patients, indicating the need for careful observation of changes in not only the anterior but also the posterior corneal surface.

Reporting the margin in pancreaticoduodenectomies: R0 versus R1

AIM

This study was conducted to analyze the changes in margin positivity in pancreaticoduodenectomies, on using a standardized protocol, which bread loafs the pancreas and duodenum in the axial plane for adenocarcinomas arising in the pancreatic head, ampulla, terminal common bile duct (CBD), and duodenum, and then to assess whether these tumor subsets involve the margins in different ways.

METHODS

The analysis was performed on 70 consecutive specimens, the pre-protocol specimens serving as the control group.

RESULTS AND CONCLUSIONS

Tumors originating from the pancreatic head, ampulla, terminal CBD, and duodenum showed a consistent increase in their R1 incidence, post-protocol. Ampullary tumors showed the greatest upward change in R1 positivity. The highest incidence of margin positivity was seen in pancreatic head adenocarcinomas (80%), then distal CBD tumors (60%), and finally the ampullary tumors (39%). In pancreatic head adenocarcinomas, R1 increased from 55% to 80%, distal CBD from 50% to 60%, and ampullary from 17% to 39%. Duodenal adenocarcinomas had no R1 in both pre- and post-protocol groups. The tumors also had different patterns of margin involvement. Ampullary tumors involved only the posterior margin, pancreatic adenocarcinomas involved the superior mesenteric vein (SMV) groove more often than the posterior margin, and distal CBD tumors involved the posterior margin and SMV groove equally. The size of the tumor made a significant difference in pancreatic head carcinomas with tumor size less than or equal to 2 cm, showing an R1 incidence of 38%, while those above 2 cm had an R1 incidence of 68%.

Morphological measurements of the posterior surface of the normal proximal tibia in a healthy Chinese population

BACKGROUND

To measure and calculate the morphological parameters and determine the anatomical characteristics of the posterior surface of the proximal tibia in a healthy Chinese population.

METHODS

A total of 150 volunteers with normal knees were enrolled. The parameters in the multi-slice spiral computed tomography (MSCT) three-dimensional (3-D) reconstruction images were measured and calculated by two independent qualified observers. The differences and correlation were investigated. The intraclass correlation coefficient (ICC) was used to assess inter-observer reliability.

RESULTS

The posterior margin of the tibial plateau is presented as two superior arc-shapes. The central angles of these arcs were 118°±14° (medial) and 106°±20° (lateral). The radii of these arcs both showed a skewed distribution. The median radii of the arcs were 22 mm in the medial and 20mm in the lateral. There were two significant angles present in the sagittal plane of the posterior cortex of the proximal tibia. The first angles were 39°±7° (medial) and 47°±7° (lateral). The second angles were 39°±4° (medial) and 41°±5° (lateral). Significant differences were observed in the central angles and the first angles but not in the second angles between the medial and lateral. There were no significant differences between different gender groups, and between left and right limbs. All of these parameters exhibited excellent to moderate ICC.

CONCLUSION

Due to the varying anatomic morphology between the postero-medial and postero-lateral surface of the proximal tibia, the internal fixation implants of these two parts should be designed differently.