[Comparison of visual effects after LASIK in myopia between centered on the coaxially sighted corneal light reflex and line of sight].

OBJECTIVE: To compare visual acuity, refractive outcome, high order aberrations, contrast sensitivity and subjective symptom of myopia with laser in situ keratomileusis (LASIK) centered on the coaxially sighted corneal light reflex (CSCLR group) and the conventional ablation of line of sight (LOS group). METHODS: With prospective, double-blind, randomized, controlled trial, the right eyes of patients were included and divided into two groups according to random stratified grouping. Two hundred and ten myopic eyes were treated with centration on the coaxially sighted corneal light reflex and 210 myopic eyes treated with centration on pupil center(line of sight). The parameters of visual acuity, refractive outcome, ablation center distance from visual axis, corneal high order aberrations, subjective discomfort glare and shadowing incidence rate, contrast sensitivity between the two groups were measured and compared up to 6months post operation. Consistent with the measurement data, normal distribution using the group t-test, non-normal distribution of measurement data using the group wilcoxon rank-sum test and count data using chi-square test. RESULTS: The data of postoperative UCVA, BCVA, MRSE efficacy index and safety index showed no statistical difference between the CSCLR and the LOS group up to 6months post operation(P> 0.05). 3% lost one line or more of BCVA in the CSCLR group,and 9% in the LOS group postoperatively, χ(2)= 6.38, P=0.01. The ablation center deviation was (0.19±0.15) mm from visual axis(pentacam system default setting) in CSCLR group and (0.43±0.22) mm in the LOS group. Ablation center deviation was statistically significantly shorter in the CSCLR group (t=-2.59, P<0.01). The postoperative increased total cornea higher order aberrations was 0.150 µm in CSCLR group and 0.193 µm in LOS group, the difference was statistically significant, Z=3.21, P=0.03. The increased corneal vertical coma of CSCLR group was 0.321 µm,smaller than in the LOS group(0.464 µm), Z=4.33, P<0.01. The increased horizontal coma was 0.242 µm in CSCLR group and also smaller than the LOS group(0.353 µm), Z=4.54,P<0.01. Subjective discomfort glare and shadowing incidence rates were 8.5% and 17.5% respectively in the CSCLR and LOS group, χ(2)=7.16,P< 0.01. The one month postoperative contrast sensitivity visual acuity in the CSCLR was 1.157 ± 0.253, significantly higher than the LOS group (0.797±0.218) on 18 c/d spatial frequency, t=- 2.55, P=0.01, but with no significant difference between the two groups at 3 and 6 months. CONCLUSIONS: Myopic LASIK centered on the CSCLR achieved significant lower induction of lost of BCVA, lower induction of high order aberrations, lower risk of subjective discomfort glare and shadowing and lower decline of early contrast sensitivity by comparison to centration on the LOS, improving the quality of vision after operation. (Chin J Ophthalmol, 2016, 52: 499-506).

Role of lateral alkyl chains in modulation of molecular structures on metal surfaces.

We use low energy electron diffraction, scanning tunneling microscopy, first-principles density-functional theory, and molecular mechanics calculations to analyze the adsorption and growth of quinacridone derivatives (QA) with alkyl chains of 4 and 16 carbon atoms on a Ag(110) substrate. Surprisingly, we find that the alkyl chains determine the orientation of the molecular overlayers. While the interaction of QA and the Ag substrate is primarily due to chemical bonding of oxygen to the silver substrate, determining the molecular orientation and preferred adsorption site, the intermolecular arrangement can be adjusted via the length of alkyl chains. We are thus able to fabricate uniform QA films with very well controlled physical properties.

Long-term impact of hepatitis B, C virus infection on renal transplantation.

Chronic liver disease and its complications are major problems in renal transplant recipients. Our aim was to elucidate the influence of hepatitis B, C virus infection on the long-term outcome of renal transplantation. Four hundred and seventy-seven patients who received renal transplantation between January 1984 and December 1999, and who were followed up at our hospital were enrolled. HBsAg was detected by the RIA method and anti-HCV Ab was assayed by the second-generation RIA kit. SGOT/ SGPT were checked every 3 months. Hepatoma was diagnosed by dynamic CT scan, elevated alpha-fetoprotein, hypervascularity by angiography and confirmed by pathological examination. The prevalence of HBV, HCV, coinfected HBV/HCV was 9.9% (n = 47), 28.5% ( n = 136), 3.1% (n = 15), respectively. The incidences of hepatoma in the HBV-/HCV-, HBV-/HCV+, HBV+/HCV-, HBV+/HCV+ groups were 1.4% (n = 4), 4.4% (n = 6), 6.4% (n = 3), 6.7% (n = 1), respectively (p = 0.114). The incidences of liver cirrhosis/hepatic failure were 3.2% (n = 9), 6.6% (n = 9), 21.3% (n = 10), 20% (n = 3), respectively (p < 0.001). The frequencies of chronic liver disease were 10.4% (n = 29), 45.6% (n = 62), 66% (n = 31), 80% (n = 12), respectively (p < 0.001). Patient and graft survival rates were lower in the HBV-infected group than in the other groups. Cox regression analysis revealed that HBV infection is likely an independent risk factor for patient mortality although the statistical significance was only borderline. Patients with HBV as well as HCV infection were not at risk of graft loss according to this model of analysis. Patients with HBV infection showed higher incidences of hepatoma, hepatic failure, graft failure and death. Therefore, HBV-infected patients who are candidates for renal transplantation should be carefully evaluated. It seems that HCV infection has little influence on the outcome of renal transplant recipients. A longer period of follow-up is needed to clarify the impact of HCV on renal transplant recipients.