[Research updates on a role for retinal contrast in myopia control].

Animal research has established that signals derived from both contrast and defocus can influence refractive development, likely concurrently, so that overall refractive development reflects an integration of these primary visual signals. Important findings include the association of L/M opsin mutations with familial high myopia, axial hyperopia produced in response to form deprivation in moderate outdoor lighting levels, effective control of myopia by diffusion optics technology spectacle lenses designed to reduce retinal contrast, and all current defocus-based optical treatments which inadvertently reduce image contrast. In this review, clinical trial results of optical myopia treatment strategies that manipulate retinal contrast are considered in context of animal research outcomes. In conclusion, research suggests mild reductions in retinal contrast can slow myopia progression in children and may also have a role in defocus-based optical therapy.

[Effection of tear film stability on orthokeratology].

Orthokeratology (Ortho-K) is one of the effective methods to control the development of myopia in children and adolescents. The mechanical pressure of eyelids on the Ortho-K lens and the hydraulic effect of tears under the Ortho-K lens can alter the curvature or shape of the cornea, which can correct refractive error and control myopia development progress. The tear film is a thin layer of liquids evenly distributing in the conjunctival sac. Wearing an Ortho-K lens can decrease the tear film stability, which will influence the Ortho-K. In this article, the relevant domestic and overseas research results are summarized and analyzed, aiming to sort out and discuss the effection of tear film stability on the fitting, shaping, safety, and visual quality of the Ortho-K, as well as to provide suggestions for clinicians and researchers.

[Predictive value of magnetic resonance imaging characteristics before and after radiotherapy for the occurrence of severe radiation-induced late rectal injury in patients with rectal cancer].

Objective: Severe radiation-induced late rectal injury (sRLRI) directly affects the quality of life of patients with rectal cancer. Effective prediction of sRLRI before surgery may provide important information for the selection of surgical strategies and perioperative managements. The purpose of this study is to evaluate the feasibility of predicting sRLRI based on magnetic resonance imaging (MRI) features before and after radiotherapy for rectal cancer. Methods: This was a diagnostic study. Clinical and imaging data of 90 patients with rectal cancer receiving long-term radiotherapy from June 2013 to July 2018 in the Sixth Affiliated Hospital of Sun Yat-sen University were collected retrospectively. Case inclusion criteria: (1) rectal cancer was diagnosed by pathology and age of ≥ 18 years old; (2) patients received neoadjuvant chemoradiotherapy and anterior rectal resection; (3) follow up time ≥ 3 years; (4) patients had no history of other neoplasm. Exclusion criteria: (1) patients did not receive MRI examination in our hospital within 2 weeks before and/or 8 weeks after radiotherapy; (2) images were not good enough for evaluation; (3) medical records were incomplete; (4) patients had severe gastrointestinal diseases. According to the RTOG/EORTC classification criteria for radiation reactions, severe complications of grade 3-4 requiring surgical management were defined as sRLRI. T2WI and DWI images before and after radiotherapy were evaluated. The rectal wall thickness, bladder wall thickness, rectal sacral spacing and apparent diffusion coefficient (ADC) were measured. The receiver operating characteristic (ROC) curve was used to evaluate the predictive value of the above indicators for sRLRI. Results: Among the 90 patients with rectal cancer, 34 (37.8%) developed sRLRI. Before radiotherapy, the median rectal wall thickness of sRLRI and non-sRLRI patients was 4.530 mm and 4.355 mm, respectively; the median bladder wall thickness was 3.962 mm and 3.868 mm, respectively; the median rectal sacral spacing was 15.557 mm and 12.433 mm, respectively; the median ADC value of rectal wall was 1.620 ×10(-3) mm(2)/s and 1.653 ×10(-3) mm(2)/s, respectively. There were no significant differences in above indicators between sRLRI and non-sRLRI patients (all P>0.05). After radiotherapy, compared with non-sRLRI patients, sRLRI patients had increased rectal wall thickness (median: 8.239 mm vs. 6.223 mm, Z=-3.512, P=0.001), rectal sacral spacing (median: 17.728 mm vs. 13.885 mm, Z=-2.247, P=0.025), and change of rectal wall thickness after radiotherapy (median: 98.106% vs. 49.584%, Z=-4.169, P<0.001). After radiotherapy, there were no significant differences in the bladder wall thickness and its change value, the ADC value of rectal wall and its change rate before and after radiotherapy between the two groups (all P>0.05). The area under the curve (AUC) of the change rates of rectal wall thickness after radiotherapy, rectal wall thickness and rectal sacral spacing after radiotherapy for predicting sRLRI was 0.763, 0.722 and 0.642, respectively, while the sensitivity was 85.3%, 70.6% and 76.5%, respectively, and the specificity was 64.3%, 71.4% and 57.1%, respectively. Conclusion: Based on MRI examinations, assessments of rectal wall thickness after radiotherapy, the change rate of rectal wall thickness after radiotherapy, and rectal sacral spacing after radiotherapy are helpful for evaluating the risk of sRLRI after radiotherapy for patients with rectal cancer.

[A machine learning model on orthokeratology lens fitting based on the data of optometry examination].

Objective: To get an orthokeratology lens fitting model according to the research of the optometry examination data, which can help to improve the work efficiency and increase the hitting rate of prescription. Methods: The relationship between the basic optometry examination data and the effective optometry prescription was evaluated. We got 1 467 sets of data, including 80%(1 173) for training and 20%(294) for testing. The trail results were used for the 20% testing sets, and 100% completed sets for verification. With the contrast of accuracy, we got the influencing variables and the fitting model. Logistic regression and linear regression analysis were applied to the training set for building a fitting model, and the receiver operating characteristic curve (ROC curve) was drawn to determine the optimal threshold of the logistic regression model (1.0).The trail results are used for the 20% testing sets, 100% completed sets for verification. With the contrast of accuracy (ACC), we get the influencing variables and the fitting model. Results: Kf-FK and Ks-SK were selected as dependent variables. Through analysis of Stepwise regression, we found the influencing variables of Kf-FK were Kf(P=0.01), E(mean) (P=0.027), and CYL(P<0.001), with FK=6.23+0.866kf-1.69 E(mean)+0.16CYL, and the precision rate was 81%(r(2)=0.95). The influencing variables of Ks-SK were Ks (P<0.001), CYL (P=0.00), and E(mean) (P<0.001), with SK=6.84+0.862ks-0.28E(mean)-1.3CYL, and the precision rate was 80%(r(2)=0.93). By selecting the logistic method and decision tree analysis for glasses design, the influencing variables were KS (P<0.001)and CYL (P<0.001). The logistic function was Design=-45.7+0.82Ks+6.027CYL, and the precision rate was 87%. Conclusions: The combination of AI and medical data can verify the expert experience and guide the optometrist to locate the prescription quickly and accurately. Try to break the traditional mode of fitting with wearing the orthokeratology lens shortly, and it is possible for us to position the prescription quickly through the calculation of a computer. (Chin J Ophthalmol, 2019, 55: 105-110).

[Willingness and influencing factors of using pre-exposure prophylaxis among 301 men have sex with men in Wuhan city, 2015].

Objective: To understand willingness and influencing factors of using pre-exposure prophylaxis (Pr-EP) among men who have sex with men (MSM). Methods: Snow ball sampling was employed to recruit MSM in the social spaces (like bars and bathrooms) with focused activities by MSM and internet (QQ and Wechat) in Wuhan between August and November, 2015. 304 MSM were considered eligible when they were self-identified MSM and has had sex with men in the previous 12 months, over the age of 18 and have full civil liability. On-site and online questionnaire surveys were conducted by self-designed questionnaires to collect information including demographic characteristics, sexual risks and practices, awareness of PrEP, and willingness to use PrEP. A total of 301 qualified questionnaires were obtained. Multivariate logistic regression models were constructed to identify factors associated with willingness to use Pr-EP. Results: The mean age of surveyed MSM were (27.51±8.31) years, between18-61. 149 on-site survey, online were152; 131 MSM have regular homosexual partners, 170 MSM have not regular homosexual partners. Only 17.28% (52/301) had heard of Pr-EP before this survey, 18.32% (24/130) had heard of Pr-EP among those who had regular homosexual partners and those who had not accounted for 16.47% (28/170). 74.42% (224/301) had willingness to use Pr-EP after they knew Pr-EP was safe and effective through the survey. The proportion among those who had regular homosexual partners was 74.05%(74), and the proportion among those who had not was 74.71% (127); Among those who had regular homosexual partners, results suggested that those who were married/cohabiting were more likely to report a willingness to use PrEP compared to unmarried/divorced or widowed (OR=5.60), compared with homosexual, heterosexuality was associated with decreased odds of willingness to use Pr-EP (OR= 0.22), compared with HIV status of sexual partner was negative or uncertain, positive infection status was associated with increased odds of willingness to use (OR=7.52). Compared with MSM who have not regular homosexual partners, those who were married/cohabiting were more likely to report a willingness to use PrEP compared to unmarried/divorced or widowed (OR=9.09), compared with those who think they have risk of infection, those who do not think they have risk of infection was associated with decreased odds of willingness to use Pr-EP (OR= 0.30), compared with those with a high frequency to seek sexual partners, those not often to seek was associated with decreased odds of willingness to use Pr-EP (OR= 0.27). All above P values were<0.05. Conclusion: The awareness rate of Pr-EP among MSM in Wuhan is low in 2015, but the willingness to use Pr-EP could get a considerable increase after introduction. It is considered that promotion of Pr-EP is feasible in China, and there are different influencing factors for the willingness between two MSM subgroups (having regular homosexual partners and having no regular homosexual partners).

A report of two cases of chronic serious manganese poisoning treated with sodium para-aminosalicylic acid.

Two cases of chronic manganese poisoning were treated with sodium para-aminosalicylic acid (PAS-Na; 6 g/day in 500 ml of 10% glucose solution by intravenous drip). The results indicated that one had been clinically cured and that the other had obviously improved in clinical symptoms and signs. Thus PAS-Na appears to be an effective drug for treatment of serious chronic manganese poisoning.

Glutathione and glutathione-related enzymes in human cataractous lenses.

Glutathione and its related enzymes were measured for normal and cataractous human lenses. Glutathione decreased progressively with the development of cataracts. This decrease was more pronounced in the nucleus than in the capsule-epithelia of cataractous lenses. Glutathione reductase in nuclear extracts was relatively unchanged during cataract progress, while glutathione synthetase was significantly low in the advanced stages of cataracts. gamma-Glutamylcysteine synthetase was not measurable in the nuclei of cataractous lenses.