Test Locations Research Articles

Influence of thread pitch on material flow and mechanical properties of stationary shoulder friction stir lap welded dissimilar joint

To investigate the influence of varying pitch values on the flow behavior of materials and the mechanical attributes of stationary shoulder friction stir lap welded (SSFSLW) joints. In this paper, three kinds of tools with different pitches are designed, and the lap joint of a 6061-T6 aluminum alloy plate and an AlSi10MnMg alloy plate was realized by stationary shoulder friction stir welding. Different computational fluid dynamics (CFD) models of friction stir lap welding were founded and the connection between the pitch and material flow behavior was investigated. The increased pitch pin boosts the velocity of material in the shear layer, expands flow area of aluminum alloy material, and promotes materials flow upward along the orientation of pin thread. The pin with a 1 mm pitch results in a joint that featuring the shortest hook extension distance, the largest effective sheet thickness (EST), and the largest effective lap width (ELW). The fracture locations of shear testing are all on the base material of AlSi10MnMg alloy. Numerous dimples could be seen at the fracture appearance, and the type of fracture is ductile fracture.

P-1384. Rates of Follow-Up Testing for Chlamydia trachomatis and Neisseria gonorrhoeae Among Active-Duty Service Members

Abstract Background All patients who test positive for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) should get retested at three months to evaluate for re-infection. The United States military has previously been reported to have high rates of CT and GC, but follow-up rates have not been established for active-duty service members (ADSM) who test positive for CT or GC. This study evaluates factors associated with follow-up CT or GC testing in ADSM. Methods Positive cases of CT and GC among ADSM who were stationed at Joint Base San Antonio between January and June 2023 were evaluated. Demographic characteristics, location of testing, and the presence of symptoms were described. A patient was determined to have had follow-up testing if they had a repeat CT/GC test within 3-12 months after their initial positive test. Follow-up rates were compared among groups based on demographics, clinical setting of testing, and presence of symptoms using chi-square or Fisher’s exact test. Results Of the 200 ADSM who tested positive for CT or GC during the study period, 101 (51%) were male and the median age was 23 [IQR: 20-26] (Table 1). Women were significantly more likely to receive follow-up testing as compared to men (71% vs. 51%; p=0.003), without significant difference in follow-up testing by clinic, race, service, or original STI organism (Table 2). Women who were symptomatic at time of initial test were significantly more likely than symptomatic men to have a follow-up test (76% vs. 49%; p=0.003), but this difference did not hold for asymptomatic patients (64% vs. 53%, p=0.28) (Table 3). Conclusion Despite standardized follow-up testing recommendations, there were significantly lower follow-up testing rates in men, with the greatest difference in testing in patients who were symptomatic at presentation. While ADSM have universal access to care, the difference in follow-up testing between men and women based on presence of symptoms reinforces concerns about stigma in obtaining treatment and follow-up. Future work should study how standardization of guidelines in these populations promotes improvement in follow-up testing. Disclosures All Authors: No reported disclosures

P-1273. Connecting Underserved Communities With Saliva-Based PCR Testing for Respiratory Infection: Insights From A Mobile Lab-In-A-Van Pilot

Abstract Background Partnering with community leaders, we sought to address ongoing diagnostic testing needs in underserved neighborhoods and evaluate whether a saliva-based mobile testing program could help overcome barriers to testing for uninsured and low-income individuals. This is critical as many lack a primary care provider, cannot access reliable health information, or have limited financial resources.Figure 3.Layout of the mobile lab-in-a-van.(a) Mobile testing van top view; (b) interior work bench side view. Source: Flambeau RapidX (Delve) Methods Free SARS-CoV-2 testing was offered at popup events using the SalivaDirect extraction-free RT-qPCR protocol on a CLIA licensed van operated by Yale Pathology Labs under FDA Emergency Use Authorization; diagnostic results were available in as little as two hours. Testing locations were identified and advertised in partnership with the community. Patient perspectives on approachability, convenience, and usefulness of mobile testing were recorded via REDcap.Figure 7.Test site event coordination.(a) Screenshot of online scheduling platform; (b) screenshot of select fields from mobile testing event tracker. Results Between October 2023 and April 2024, 70 community events were hosted and 533 SARS-CoV-2 PCR tests administered. Across participants of all ages (0-91y, mean=42y), 79% (410/517) agreed it was easy to access the van and get a COVID test and 79% (411/517) agreed they were comfortable using the van. Of those tested, 59% (169/288) reported an annual household income of < $25,000; 92% (265/288) reported an income of < $50,000. In addition, 31% (160/517) were uninsured. Of those insured, 62% (142/228) identified “Public (Medicare, Medicaid, Tricare)” as their primary healthcare plan. Overall, 44% (128/290) reported getting the healthcare they need was a challenge, with 46% (134/289) reporting transportation challenges.Figure 5.Participant demographics (RP2 R0604 data though April 10, 2024) / Figure 9. Participant responses to select REDCap survey questions (RP2 R0604 data though April 10, 2024)Figure 5. (a) Self-identified race; (b) age distribution; (c) annual household income.Figure 9. (a) Ease of van access; (b) Comfort using the van; (c) Reason for choosing location. Conclusion This pilot demonstrated the positive impact a mobile testing program can have in addressing community needs. Analysis of participant demographics and identified barriers to service access underscores the program's effectiveness in addressing previously unmet testing requirements and enhancing healthcare accessibility within the target community. Moreover, feedback gathered from participants of all age groups via surveys reveals a strong consensus regarding the convenience and comfort of saliva-based testing at mobile events. This underscores the viability of mobile initiatives as a feasible approach to fulfilling future testing demands, particularly within underserved populations. Disclosures Anne L. Wyllie, PhD, SalivaDirect: Board Member|SalivaDirect: Honoraria

Genotype by environment interactions and phenotypic traits stability of the EUCLEG faba bean collection

Faba bean (Vicia faba L.) is an important pulse crop traditionally used for human nutrition and animal feeding. With a high protein content ranging from 24% to 35% of seed dry matter, considerable amounts of globulins, essential amino acids and minerals, faba bean is today an important source meeting the growing global demand for nutritious food. The objective of study was to investigate the variability of nine phenological, phenotypical and yield related traits in 220 faba bean accessions in multi-location trials across four representative European regions. Nine field trials were carried out from 2018 till 2020 in four representative European locations (Spain, Finland, Belgium and Serbia) using an augmented p-rep design containing 20 replicated checks. Significant differences among genotypes and environments were detected, being the genotype x environment interaction (GEI) the major source of variation in five of the nine evaluated traits. The “which-won-where” analyses identified two mega-environment namely South European mega environment (SE-ME) and North European mega environment (NE-ME), while the best performing and most stable genotypes according to the nine traits were identified using “means vs stability” analyses. According to the highest trait value in each mega environment several winning genotypes were identified showing better performances than some commercial varieties (controls) or checks. Our results suggest that the geographical locations falling into each mega-environment can be used as faba bean test locations. The genotype ranking for the multi-trait stability index (MTSI) revealed that the most stable and best ranking genotypes in SE-ME are G018, G086, G081, G170 and G015 while in the north mega-environment are G091, G171, G177 (Merkur), G029 and G027. Hierarchical cluster analysis and principal component analyses showed a clear correlation between the traits analysed and the botanical type. These findings indicate that botanical type is one of the most significant factors affecting development in any environment, and it must be taken into account in faba bean breeding activities. The information derived from this study provides a chance for breeding new resilient faba bean cultivars adapted to different agroecological European regions, a critical point for addressing Europe’s reliance on protein imports and enhancing sustainable agriculture practices.

The Effect of Disulfiram and N-Acetylcysteine, Potential Compensators for Sulfur Disorders, on Lipopolysaccharide-Induced Neuroinflammation Leading to Memory Impairment and the Metabolism of L-Cysteine Disturbance

Background: The role of sulfur-containing drugs, disulfiram (DSF) and N-acetylcysteine (NAC), in alleviating neuroinflammation is poorly understood. The objective of this study was to examine the effect of DSF and NAC on memory and on the metabolism of L-cysteine and inflammation-related parameters in the cerebral cortex of rats in a model of neuroinflammation induced by the administration of lipopolysaccharide (LPS). Methods: All the treatments were administered intraperitoneally for 10 days (LPS at a dose of 0.5 mg/kg b.w., DSF at a dose of 100 mg/kg b.w, and NAC at a dose of 100 mg/kg b.w.). Behavior was evaluated by the novel object recognition (NOR) test and object location (OL) test, and the level of brain-derived neurotrophic factor (BDNF) was assayed to evaluate neuronal functioning. Cerebral cortex homogenates were tested for hydrogen sulfide (H2S), sulfane sulfur, sulfates, non-protein sulfhydryl groups (NPSH), nitric oxide (NO), and reactive oxygen species (ROS) by biochemical analysis. Results: Neither DSF nor NAC alleviated LPS-induced memory disorders estimated by the NOR test and OL test. The studied compounds also did not affect significantly the levels of BDNF, ROS, NO, H2S, and sulfane sulfur in the cerebral cortex. However, we observed an increase in sulfate concentration in brain tissues after LPS treatment, while DSF and NAC caused an additional increase in sulfate concentration. On the other hand, our study showed that the administration of DSF or NAC together with LPS significantly enhanced the cortical level of NPSH, of which glutathione is the main component. Conclusions: Our study did not confirm the suggested potential of DSF and NAC to correct memory disorders; however, it corroborated the notion that they reduced oxidative stress induced by LPS by increasing the NPSH level. Additionally, our study showed an increase in sulfate concentration in the brain tissues after LPS treatment, which means the upregulation of sulfite and sulfate production in inflammatory conditions.

Evaluation of Technologies for Nondestructively Determining Concrete Pavement Thickness

The U.S. Army Engineer Research and Development Center (ERDC) was tasked by the U.S. Air Force (USAF) to evaluate the capability of emerging nondestructive testing equipment to accurately estimate the thickness of pavement surfaces without requiring large footprint equipment or pavement repairs. The ERDC research team conducted an evaluation of eleven nondestructive technologies, including eight ground penetrating radar devices and three different seismic technologies, on nineteen concrete test locations with varying pavement thicknesses. For each of the different pavement types, a single core was extracted to provide calibration points. The involved vendors and researchers estimated initial thickness, and upon receiving the calibration core thicknesses, final thickness estimates were computed. The accuracy of each technology was quantified by calculating the absolute difference between the actual core measurement and the estimated measurement. This paper describes the eleven different technologies, their performance on the test locations, and comparisons in terms of accuracy and implementation difficulty.

Study on erosion and residual strength of tee in high pressure manifold

ABSTRACT The complex fluid and solid particles inside the throttled pressure well manifold will cause a certain degree of erosion and wear on the inner wall, which will accumulate to form erosion defects and make the wall thickness thin, which may eventually lead to the failure of the tee due to irreversible damage, triggering serious safety accidents. In order to avoid the occurrence of such safety accidents, in-service training must be non-destructive testing to ensure the safe operation of the manifold. Therefore, for the tee of the throttle manifold, an erosion simulation model was established to carry out the study on the erosion and wear law of the tee with different displacements and sand ratios and analyze the erosion parts of the tee under different working conditions; and based on the erosion-prone parts of the tee, a residual strength simulation model of the tee with defects was established to carry out the influence of the depth of the defects and the internal pressure on the residual strength of the tee. The analyzed results can provide a theoretical basis for the nondestructive testing location and replacement timing of the tee.

Impact on the Proper Use of Antimicrobials for Patients with Gram-negative Bacteremia due to a Change in Testing Location of Positive Blood Culture Specimens

Impact on the Proper Use of Antimicrobials for Patients with Gram-negative Bacteremia due to a Change in Testing Location of Positive Blood Culture Specimens

Subsurface Soil Enhancement to Strengthen the Ground under the Concrete Pavements in Operating Zones.

This paper outlines the suitable techniques employed for soil improvement in Heavy industries, oil & gas refinery, and petrochemical Plants. The materials and procedures will be detailed within this paper, with any exceptions to the specifications clearly indicated. The primary scope of work involves the filling of sand and gravel, as well as the injection of soil cement at designated cavity locations beneath the concrete grade slab in areas where space is limited and accessibility to the ground is challenging. The proposed method aims to fill the voids between the top of the foundation soil and the underside of the slabs, while ensuring the provision of all necessary equipment, tools, and a skilled workforce for geotechnical operations. Each testing location, including DCP Testing, void detection, and the installation of shallow monitoring wells, will be addressed in accordance with the specific site conditions.

Proximity to traffic is associated with worse symptom severity in patients with chronic rhinosinusitis with nasal polyps.

Environmental exposures may be associated with increased severity of chronic rhinosinusitis (CRS). However, research examining associations of traffic related air pollution with CRS is limited. The purpose of this study was to determine the association between residential traffic proximity and CRS with nasal polyposis (CRSwNP) severity in an existing database of adults in the United States. This study was conducted on data gathered from 181 participants documented in the NAVIGATE I and NAVIGATE II randomized control trials within the OPTINOSE database. Zip codes for the testing locations of each participant were recorded and EPA traffic proximity data was extracted for each location. Traffic proximity was defined as the average annual daily traffic at major roads within the zip code. SNOT-22 scores were assessed as a measure of CRSwNP severity. The association between traffic proximity and SNOT-22 scores were determined using multiple linear regression. There were 81 female and 100 male participants. The majority of participants were White not Hispanic (84.5%). On adjusted regression, there was a weak but significant direct association of increased traffic proximity with SNOT-22 scores (β: 0.003; 95% CI: 0.0003, 0.006; p=0.03). Increasing traffic proximity, suggestive of exposure to higher levels of pollution, was significantly associated with increased severity of CRSwNP. These findings suggest that pollutant exposure should be considered in CRS assessment and management. Future prospective studies on the association of traffic related air pollution and how pollutants affect symptom severity, may help to better elucidate the role the environment has in CRS.

SARS-CoV-2 risk factors among symptomatic vaccinated adults attending community testing locations in the Netherlands from June 2021 till February 2022.

Most studies on risk factors for a SARS-CoV-2 infection were conducted in the pre-vaccination era with many non-pharmaceutical prevention measures in place. We investigated risk factors for symptomatic SARS-CoV-2 infections in vaccinated persons in a period with a varying degree of prevention measures. In a test-negative case control study among vaccinated adults attending community COVID-19 testing locations between June 1st 2021 till February 28th 2022, we compared symptomatic cases with symptomatic controls (to study risk factors specific for SARS-CoV-2) and with asymptomatic controls (to study risk factors that could apply to respiratory infections in general). We examined potential risk factors including household composition and mitigation behaviour by logistic regression, adjusting for age, sex, and week of testing. Risk factors for a positive SARS-CoV-2 test when symptomatic cases were compared to symptomatic controls were: having a household size of more than 4 (adjusted odds ratio: 1.47; 95% CI 1.14-1.92), being a healthcare worker (1.27;1.18-1.47), and visiting busy locations outside (1.49;1.19-1.87). When symptomatic cases were compared to asymptomatic controls, a household size of more than 4 members (1.71;1.25-2.33), living with children aged 0-12 (1.59;1.12-2.26), visiting busy locations outside (1.64;1.24-2.17) were independent risk factors for a positive SARS-CoV-2 test. Risk factors for separate periods and waves differed from the study period as a whole. This study was conducted in a period with a varying degree of prevention measures. Among vaccinated individuals, we identified several SARS-CoV-2 specific risk factors and SARS-CoV-2 risk factors that could be more general for respiratory infections. For SARS-CoV-2 transmission more attention could be given to visiting busy outdoor locations, having a household size that consists of more than 4 persons, being a healthcare worker, and living with children aged 0-12. Risk factors varied with different phases in the pandemic, emphasizing the importance of repeated assessment of risk factors.

INVESTIGATION OF VERTICAL DISTRIBUTION OF ANTHROPOGENIC RADIONUCLIDES IN SEDIMENTS OF WATERCOURSES OF THE “DEGELEN” SITE

The article presents research data on the vertical distribution of radionuclides in bottom sediments of water streams at the former Degelen test location of the Semipalatinsk Test Site. As part of research, bottom sediments were sampled in the form of undisturbed cores. Based upon findings on the content of radionuclides in bottom sediment samples, histograms were plotted to describe the vertical distribution of radionuclides. The distribution of man-made radionuclides such as 241Am, 137Cs, 90Sr and 3Н is addressed. The content of 241Am is <DL in all collected samples. That of 137Cs and 90Sr varied from 3±1 to 180±20 Bk/kg and 10±1 to 13,000±2,000 Bq/kg, respectively. The content of 3Н was determined in two forms: in the free water (for bottom sediment samples from the Uzynbulak cr.) and in the tightly bound form. The content of 3Н in the free water was 6,400±640 Bq/kg to 21,000±2,100 Bq/kg, in the tightly bound form – 8±1 Bq/kg to 5,300±550 Bq/kg.

Exploring the potential of service robots in guiding patients and assisting mobility in medical facilities

Service robotics is bringing about innovative changes in various industrial sectors, with its significance expected to increase even further in the future. This paper reports on a pilot study in which a mobile robot was utilized to guide patients who visited a clinic for examination purposes to their respective testing locations. Additionally, we conducted a survey among the patients regarding their experiences with the test and facility guide robots. Furthermore, to explore the potential of service robotics in taking over and assisting with mobility-related tasks not limited to test guidance, especially in hospitals, we carried out a research survey targeting employees at a university hospital. This survey aimed to assess the extent to which service robotics could contribute to supporting mobility-related tasks.

Longitudinal Changes of Visual Sensitivity With Geographic Atrophy Progression Assessed by Defect-Mapping Microperimetry.

To determine the relationship between structural and functional changes over time in the progression of geographic atrophy (GA) as assessed by defect-mapping microperimetry, an approach optimized to characterize the spatial extent of deep visual sensitivity losses. A total of 57 eyes from 50 participants underwent defect-mapping microperimetry testing of the central 8° radius (with a 10-dB stimuli presented once each at 208 locations) over a median of five visits, scheduled at 3-monthly intervals. GA lesion(s) on fundus autofluorescence in the corresponding region tested on microperimetry at each visit were manually annotated. At a global level, change of GA extent in the central 8° radius explained a large proportion of the variance in the change in the proportion of locations missed (nonresponse) on defect-mapping microperimetry (R2 = 0.52). Locally, test locations that were entirely outside or within GA lesion(s) had a 0.3% (P = 0.305) and 2.3% (P < 0.001) probability of worsening between the two visits, respectively. In contrast, test locations with a 0% to 25%, 25% to 50%, 50% to 75%, or 75% to 100% change in the extent of GA overlapping between visits had a 4.1%, 12.0%, 17.5%, and 37.9% probability of worsening, respectively (all P < 0.001). This study confirms that longitudinal changes in GA extent are associated with functional changes on defect-mapping microperimetry, both on a global and local level. These findings highlight the expected functional relevance of GA progression, and demonstrates the potential effectiveness of this microperimetry testing strategy for capturing visual function decline associated with GA progression.

Popularity of HIV self-tests may say more about the state of our primary care system than about the device itself.

In Canada, HIV transmission continues to disproportionately affect the same communities of gay men, bisexual men and men who have sex with men (gbMSM); members of African, Caribbean or Black communities (ACB); people who use injection drugs; Indigenous people; and women who belong to the aforementioned groups. While primary care is an ideal location for HIV testing for members of these groups, many people do not have access to such healthcare services. In response, we launched GetaKit to distribute HIV self-tests. In light of reduced access to healthcare services as a result of the pandemic and in anticipation of Health Canada's approval of an HIV self-test, a clinician-scientist research team at the University of Ottawa developed GetaKit: an online platform to provide access to sexual health services. When GetaKit first launched in Ottawa in July 2020 with funding from the Ontario Ministry of Health, its objectives were to ensure that access to the newly approved device remained 1) clinically appropriate, 2) accessible and 3) linked to care. Over the course of the study, there were a stable number of individuals who reported having never been tested for HIV before. These individuals tended to be younger and more likely to be members of racialized minority groups; similar characteristics to those who also face the most barriers to primary care access. With new reports indicating that nearly six million Canadians are without a primary care provider, it was proposed that the popularity of the HIV self-test may tell more about this lack of access than about the utility of the device itself. While projects like GetaKit should be part of the broader strategy to overcome historic testing barriers, such as geographic distance and inconvenient clinic hours, it is important that this occurs in an environment where a strong primary care health system can support treatment, follow-up and specialist referrals, as required.

Popularity of HIV self-tests may say more about the state of our primary care system than about the device itself.

In Canada, HIV transmission continues to disproportionately affect the same communities of gay men, bisexual men and men who have sex with men (gbMSM); members of African, Caribbean or Black communities (ACB); people who use injection drugs; Indigenous people; and women who belong to the aforementioned groups. While primary care is an ideal location for HIV testing for members of these groups, many people do not have access to such healthcare services. In response, we launched GetaKit to distribute HIV self-tests. In light of reduced access to healthcare services as a result of the pandemic and in anticipation of Health Canada's approval of an HIV self-test, a clinician-scientist research team at the University of Ottawa developed GetaKit: an online platform to provide access to sexual health services. When GetaKit first launched in Ottawa in July 2020 with funding from the Ontario Ministry of Health, its objectives were to ensure that access to the newly approved device remained 1) clinically appropriate, 2) accessible and 3) linked to care. Over the course of the study, there were a stable number of individuals who reported having never been tested for HIV before. These individuals tended to be younger and more likely to be members of racialized minority groups; similar characteristics to those who also face the most barriers to primary care access. With new reports indicating that nearly six million Canadians are without a primary care provider, it was proposed that the popularity of the HIV self-test may tell more about this lack of access than about the utility of the device itself. While projects like GetaKit should be part of the broader strategy to overcome historic testing barriers, such as geographic distance and inconvenient clinic hours, it is important that this occurs in an environment where a strong primary care health system can support treatment, follow-up and specialist referrals, as required.

An experimental assessment of five distinct solar distiller designs' thermo-economic performance

This study evaluates five solar still (SS) designs—spherical, cylindrical, pyramid, conventional, and double-slope—to determine the most efficient configuration for freshwater production at a specific test location. In initial testing, the unmodified SS designs were compared to a traditional distiller. Modifications were then made to the spherical SS by adding external reflectors, followed by integrating phase change materials (PCM) with silver nanomaterials. The final configuration tested included the spherical SS with reflectors, fans, and external condensers. Results showed substantial productivity increases over the conventional solar still (CSS), with production enhancements of 115%, 105%, 68%, and 31% for the spherical, cylindrical, pyramid, and double-slope SS designs, respectively. The spherical SS with optimized Nano-PCM and reflectors achieved a 230% increase over CSS (10420 kg/m² vs. 3150 kg/m²). The best-performing configuration, combining a fan, condenser, and reflectors, yielded a 253% improvement, with daily outputs of 11.3 kg/m² compared to 3.2 kg/m² for CSS. Economic analysis revealed that the optimized spherical SS configuration reduced the cost of freshwater production to 0.01 $/kg, significantly lower than the conventional SS cost of 0.024 $/kg.

Optimization of testing protocols to screen for COVID-19: a multi-objective model.

In this paper we develop a new multi-objective simulated annealing (MOSA) algorithm to generate optimal testing protocols for infectious diseases, using the COVID-19 pandemic as our context. A SEIR (susceptible-exposed-infected-recovered) epidemiological model is embedded as the computational platform for our MOSA algorithm to optimize testing protocols for screening across three joint objectives: minimum cost of test materials, minimum total infections over the testing horizon, and minimum number of false negatives over the horizon. We demonstrate the application of this optimization tool to recommend screening protocols for K-12 school districts in the U.S.State of North Carolina. Our approach is scalable by population coverage and can be employed at the level of individual school districts or regional collections of districts, individual schools or collections of schools across a district, business sites, or nursing homes, among other congregate settings where individuals may be screened prior to gaining entry to the site. The algorithm can be solved two ways, generating either independent optimal protocols across individual testing locations, or a common protocol covering all locations in the collection of testing sites. Our findings can be used to inform policy decisions to guide the development of effective testing strategies for controlling the spread of COVID-19 or other pandemic diseases in a wide range of congregate settings across various geographic regions.

Bias evaluation and minimization for estuarine total dissolved solids (TDS) patterns constructed using spatial interpolation techniques

This study evaluated and minimized bias in estuarine total dissolved solids (TDS) patterns predicted using geostatistical approaches. The acquired TDS data was divided into three parts: 29 points (60 %) for predicting TDS patterns with spatial interpolation techniques, 12 points (25 %) for validation and bias correction, and 7 points (37 %) for testing the corrected bias. Inverse Distance Weighting (IDW), Ordinary Kriging (OK), Universal Kriging (UK) and Regression Kriging (RK) were applied to map TDS patterns. R-square and Relative Error of Mean showed significant discrepancies between observed and predicted TDS levels. The Mean field bias (MFB) correction technique was applied to minimize bias in TDS patterns. After correcting bias, the TDS values predicted by IDW, OK, UK and RK at random locations deviated from measured values by −2.85 %, 0.71 %, 4.66 %, and − 6.03 % respectively. At the test locations, these values deviated by −1.45 %, 1.41 %, 2.11 %, and − 2.65 % respectively.

Parafoveal Microperimetric Retinal Sensitivity as a Key Parameter Associated with Vision Loss in Retinitis Pigmentosa.

Background: Although optical coherence tomography (OCT) is useful in determining outer retinal architecture, it may be suboptimal when monitoring subtle changes in retinitis pigmentosa (RP) patients. The aim of this study is to investigate precise microperimetric parameters for disease severity identification in RP patients. Methods: A cross-sectional and retrospective study. Thirty-nine eyes of 39 RP patients were included. Associations between logMAR visual acuity (VA), spectral-domain OCT, fundus autofluorescence imaging (FAF), and various microperimetric measures were evaluated. Microperimetric test locations were grouped into "foveal", parafoveal "inner ring", and perifoveal "outer ring". Independent variables were analyzed based on logistic regression, then assessed using area under the receiver operating characteristic curve (AUROC). Results: Among all microperimetric measures, linear regression analysis indicated that mean retinal sensitivity and deep scotoma count at the parafoveal inner ring were the principal parameters associated with decreased VA. The AUROC was highest for deep scotoma count at the inner ring at a value of 0.829, with the cut-off point at 3.5. A visual function index was then established according to the number of parafoveal deep scotoma points, in order of mild (0 points), moderate (1-3 points), and severe (4 or more points). Our microperimetric visual function index also correlated significantly to logMAR VA and previously established FAF patterns. Conclusions: Our study discovered deep scotoma count at the parafoveal inner ring to be a key microperimetric parameter in evaluating vision loss in RP patients. Those with four or more deep scotoma points at the parafoveal inner ring are more likely to have functional low vision.