Preliminary Application of a Continuous Functional Contrast Visual Acuity System in the Assessment of Visual Function in Dry Eye Patients.

Purpose: To investigate the feasibility and efficacy of a continuous functional contrast visual acuity (CFCVA) system in the assessment of visual function in dry eye disease (DED). Methods: Twenty patients with DED and 15 normal controls were recruited. Subjective symptoms were evaluated using the Ocular Surface Disease Index (OSDI) questionnaire, and tear film stability was assessed by a noninvasive corneal topographer. Under natural blinking conditions, the custom-built CFCVA system was used to take serial visual acuity measurements at 100%, 25%, 10%, and 5% contrast for 60 seconds. A 5-minute measurement at a 100% contrast level was defined as the stress test (ST). Mean CFCVA was defined, and visual maintenance ratio (VMR) was the ratio of mean CFCVA divided by baseline visual acuity. Results: In both groups, VMR decreased and mean CFCVA (logarithm of the minimum angle of resolution) increased with decreasing optotype contrast (from 100% to 5%). In ST, the ST VMR at the fourth and fifth minutes (VMR54 and VMR55) showed the strongest correlations with OSDI total, ocular symptoms, and vision-related function (-0.646 and -0.598, -0.688 and -0.693, and -0.599 and -0.555, respectively, P < 0.05). VMR54 and VMR55 also demonstrated the best discriminating ability for detecting DED, with areas under the curve of 0.903 and 0.867, respectively. Conclusions: Extending the continuous measuring time was more effective for detecting vision-related functional abnormalities in patients with DED than simply decreasing the optotype contrast level. Translational Relevance: The proposed CFCVA system and associated parameters offer a potential method for quantifying and interpreting the visual symptoms of DED in clinical care.

Comparison of Refractive Prediction Accuracy With Three Optical Devices.

PURPOSE: To investigate refractive prediction accuracy with the OA-2000 (Tomey), Anterion (Heidelberg Engineering), and IOLMaster 500 (Carl Zeiss Meditec AG) in patients with cataract. METHODS: Patients with cataract referred for phacoemulsification were enrolled and scanned with the OA-2000, Anterion, and IOLMaster 500 in random order. The success rate of axial length (AL) measurements per device was calculated and a chi-square test was used to identify the differences in acquisition rate between the three devices. The Bland-Altman method was used to appraise the agreement of biometric parameters between the three devices. Four different formulas (Barrett Universal II [BUII], Haigis, Holladay 1, and SRK/T) were included in the study. The parameters of refractive prediction accuracy comprised predictive error (PE), absolute PE (AE), and percentages of eyes with a PE within ±0.50, ±0.75, and ±1.00 diopters (D). RESULTS: The acquisition rates of AL measurements with the OA-2000 and Anterion were 97.35% and 94.70%, respectively (chi-square = 3.82, P > .05). A significantly lower acquisition rate of 84.82% was obtained with the IOLMaster 500 compared with the other two devices (P < .05). Bland-Altman analysis identified good agreement between the three biometers with narrow 95% limits of agreement for flat and steep keratometry (K1 and K2), anterior chamber depth (ACD), and AL. For PE, only the differences between the Anterion and IOLMaster 500 with the Barrett UII and Haigis formulas were statistically significant (P < .05). The three devices revealed no statistically significant differences in MAE, MedAE, and the proportion of eyes with a PE within ±0.50, ±0.75, and ±1.00 D (P > .05). CONCLUSIONS: The OA-2000 and Anterion showed a similarly higher acquisition rate of AL measurements than the IOLMaster 500 in patients with cataract. Good agreement for K1, K2, ACD, and AL was found between the three biometers. Regarding refractive prediction accuracy, the Anterion did not significantly outperform both the OA-2000 and IOLMaster 500. [J Refract Surg. 2023;39(1):48-55.].

Causal Associations of Thyroid Function and Age-Related Macular Degeneration: A Two-Sample Mendelian Randomization Study.

PURPOSE: To determine whether causal association lies between thyroid function and age-related macular degeneration (AMD) risk in human beings. DESIGN: Two-sample Mendelian randomization (MR) study. METHODS: The single-nucleotide polymorphisms associated with free thyroxine (FT4) and thyroid-stimulating hormone (TSH) were selected from a genome-wide association study (GWAS) of 72,167 individuals of European descent. Summary-level data for AMD were obtained from a GWAS published by the International Age-related Macular Degeneration Genomics Consortium of 33,526 individuals (16,144 cases and 17,832 controls). An inverse-variance-weighted (IVW) method was the main MR analysis. Maximum likelihood, weighted median, MR-Egger, MR-pleiotropy residual sum outlier methods were used for the sensitivity analysis. RESULTS: An increase of 1 SD in genetically predicted FT4 levels was found to be significantly associated with an 18.9 % increase in the overall AMD risk (P = .005). In the multivariable MR analysis controlling for TSH level, the causal effect of FT4 level on the risk of AMD remained (odds ratio [OR] = 1.207, P = .004). A 1-SD increase in TSH levels was nominally associated with a 10.0% decrease in the overall AMD risk (P = .032). After adjusting for FT4 level by multivariable MR analysis, no direct causal relationship was found between TSH level and AMD risk (95% CI = 0.810, 1.125, P = .582). CONCLUSIONS: Genetic variants predisposing to higher FT4 levels within the normal range were associated with higher AMD risk. Further studies are required to understand the mechanism underlying this putative causal relationship.

Advancements in the Application of Ultrasound Elastography in the Cervix.

Ultrasound elastography is a modern imaging technique that has developed rapidly in recent years. It enables objective measurement of tissue stiffness, a physical property intuitive to the human sense of touch. This novel technology has become a hotspot and plays a major role in scientific research and academic practice. Presently, ultrasound elastography has been used in the identification of benign and malignant tumors in superficial organs, such as breast and thyroid, providing clinically accurate diagnosis and treatment. The method has also been widely used for the liver, kidney, prostate, lymph nodes, blood vessels, skin and muscle system. In the application of cervical lesions, ultrasound elastography can distinguish normal cervix from abnormal cervix and differentiate benign from malignant lesions. It can significantly improve the diagnostic specificity for cervical cancer and is also useful for assessing infiltration depth and stage of cervical cancer, as well as predicting chemoradiotherapy treatment response. For cervical evaluation during pregnancy, ultrasound elastography is useful for assessing cervical softening and predicting premature delivery and outcome of induced labor. This article reviews the principles of ultrasound elastography as well as the current status and limitations in its application for cervical lesions and the cervix during pregnancy.

Low-frequency HIFU induced cancer immunotherapy: tempting challenges and potential opportunities.

Immunotherapy is playing an increasingly important role in the treatment of tumors. Different from the traditional direct killing or excision therapies, immunotherapy depends on autologous immunity to kill tumor cells and tissues by activating or enhancing the body's immune system. Large numbers of recent studies suggest that low-frequency HIFU can not only enhance the intensity of the body's anti-cancer immune response, but also improve the efficiency of immunotherapy drug delivery to strengthen the effects of tumor immunotherapy. The focused ultrasound (FUS) destructs the tumor and simultaneously generates tumor debris and tumor-associated antigens, which enhances the immunogenicity of the tumor and stimulates the immune cells, inducing the body's immune response. Microbubbles are clinically used as a contrast. As a matter of fact, the addition of microbubbles can reinforce the destructive effect of FUS on the tumor and activate a stronger immune response. The combined application of ultrasound and microbubbles can more effectively open the blood brain barrier (BBB), which is beneficial to improving the intake of immune cells or immunotherapy drugs and exerting a positive influence in the lesion area. Currently, microbubbles and nanoparticles are commonly used as gene and drug carriers. Using ultrasound, the immune-related gene or antigen delivery itself can enhance the immune response and improve the efficacy of the immunotherapy.

Design of liver functional reserve monitor based on three-wavelength from red light to IR.

BACKGROUND: The preoperative evaluation of liver functional reserve is very important to determine the excision of liver lobe for the patients with liver cancer. There already exist many effective evaluation methods, but these ones have many disadvantages such as large trauma, complicated process and so on. OBJECTIVE: Therefore, it is essential to develop a fast, accurate and simple detection method of liver functional reserve for the practical application in the clinical engineering field. METHODS: According to the principle of spectrophotometry, this paper proposes a detection method of liver functional reserve based on three-wavelength from red light to infrared light (IR), in which the artery pulse, the vein pulse and the move of tissue are taken into account. RESULTS: By using photoelectric sensor technology and excreting experiment of indocyanine green, a minimally invasive, fast and simple testing equipment is designed in this paper. CONCLUSIONS: The testing result shows this equipment can greatly reduce the interference from human body and ambient, realize continuous and real-time detection of arterial degree of blood oxygen saturation and liver functional reserve.

[Research on Three-dimensional Temperature Field Reconstruction in Biological Tissue Based on Multi-island Genetic Algorithm].

The nondestructive reconstruction of three-dimensional(3D)temperature field in biological tissue is always an important problem to be resolved in biomedical engineering field.This paper presents a novel method of nondestructive reconstruction of 3Dtemperature field in biological tissue based on multi-island genetic algorithm(MIGA).By this method,the resolving of inverse problem of bio-heat transfer is transformed to be a solving process of direct problem.An experiment and its corresponding simulation were carried out to verify the feasibility and reliability.In the experiment a high purity polypropylene material,whose thermophysical parameters were similar to the fat tissue being tested,were adopted so that it could avoid the negative results created by the other factors.We set the position P(x,y,z)as the point heat source in the biological tissue and its temperature t as optimization variable,got the experimental temperature values of the points in a module surface,subtracted them from the corresponding simulating temperature values in the same module surface,and then took the sum of absolute value.We took it as the objective function of successive iteration.It was found that the less the target value was,the more optimal the current variables,i.e.the heat source position and the temperature values,were.To improve the optimization efficiency,a novel establishment method of objective function was also provided.The simulating position and experimental position of heat source were very approximate to each other.When the optimum values are determined,the corresponding 3D temperature field is also confirmed,and the temperature distribution of arbitrary section can be acquired.The MIGA can be well applied in the reconstruction of 3Dtemperature field in biological tissue.Because of the differences between the MIGA and the traditional numerical methods,we do not have to acquire all the data of surface.It is convenient and fast,and shows a prosperous application future.

Diagnosis of breast tumor using thermal tomography q-r curve.

Metabolic heat, the product following the metabolism of cells, is closely related to the pathological information of living organisms, which means there are strong connections between the heat distribution and the pathological state of the living organism. The mathematical function δ is introduced in the classical Pennes bioheat transfer equation as a point heat source, and by simplifying the boundary condition, a bioheat transfer model is established. Based on the temperature distribution of the human body surface, the q−r curve of heat intensity q varying with depth r is acquired while combining the fitting method of the Lorentz curve. According to 34,977 clinical confirmed cases and the corresponding classified statistics, diagnostic criteria (for breast diseases) for judging diseases by the q−r curve are proposed. The P -value of our statistics is <0.05 , which means our classified statistics are reliable. Six typical clinical examinations are performed, and the diagnosis results are very consistent with those of B-ultrasonic images, molybdenum target x-ray, and pathological examination, which suggests that the method of diagnosing diseases with a q−r curve has very good prospects for application. It is radiation free and noninvasive to the human body.

Q-r curve of thermal tomography and its clinical application on breast tumor diagnosis.

Heat is the product following the metabolism of cells, and the metabolism is closely related with the pathological information of living organism. So, there are strong ties between the heat distribution and the pathological state in living organism. In this paper, the mathematical function δ is introduced in the classical Pennes bio-heat transfer equation as the point heat source. By simplifying the boundary conditions, a novel bio-heat transfer model is established and solved in a spherical coordinate system. Based on the temperature distribution of human body surface, the information of heat source is mined layer by layer, and the corresponding q-r curve of heat intensity varying with depth is acquired combining the fitting method of Lorentz curve. According to a large number of clinical confirmed cases and statistics, the diagnostic criteria judging diseases by q-r curve are proposed. Five typical clinical practices are performed and four of the diagnosis results are very consistent with those of molybdenum target (MT) X-ray, B-ultrasonic images and pathological examination, one gives the result of early stage malignant tumor that MT X-ray and B-ultrasonic can't check out. It is a radiation-free green method with noninvasive diagnostic procedure and accurate diagnosis result.

A simple and efficient method for breast cancer diagnosis based on infrared thermal imaging.

This study aims to evaluate the feasibility and efficacy of quantitative diagnosis through thermal analysis of abnormal metabolism. In this paper, an analytical-based steady-state solution for the thermal inverse problem was developed, considering an equivalent point heat source embedded in the tissue. Based on this solution, we developed a simple and efficient algorithm that generates solutions for the nonlinear heat conduction model. Using the nonlinear fitting analysis, a regular distribution can be derived from the raw thermal patterns of the skin surface above the tumor, and the power and depth of the equivalent heat source can be derived to investigate whether the tumor is malignant or benign. The thermal power Q of internal heat source was estimated to predict the satisfactory approaches to distinguish between benign and malignant tumors. The results of four clinical cases (female patients with malignant tumor and benign tumor) show that the estimated values of the power of the heat sources in malignant cases (fatty: Q = 0.34851 W; dense: Q = 0.46933 W) are both far greater than the ones in benign (fatty: Q = 0.04721 W; dense: Q = 0.07717 W), irregardless of the breast density. The correlation coefficients (R (2)) of the nonlinear curve fittings are all above 0.98. The new thermal method proposed in this study would help to improve the preciseness of diagnosis on breast masses (malignant or benign).