Excess length of hospital stay due to healthcare acquired infections. Methodologies evaluation

BACKGROUND: Healthcare acquired infections (HAI) cause an increase of burden and in particular excess length of hospital stay (LOS) accounts for approximately up to 90% of total costs. Therefore accurate estimation of extra hospital stay due to healthcare acquired infections is very important. METHODS: The authors carried out a review comparing the principal methods internationally used for estimating the excess LOS attributable to healthcare acquired infections. RESULTS: The methods described and analysed are: 1) Implicit physician assessment; 2) appropriateness evaluation protocol; 3) unmatched case-control; 4) matched case-control; 5) regression analysis; 6) multistate model. The various methodologies are described underlining advantages and limits which researchers need to know before starting any economic analysis. CONCLUSIONS: Overall, studies taking into account the time-dependent nature of HAI show to give more precise and reliable results

Testing a phantom eye under various signal-to-noise ratio conditions using eleven different OCT devices

We compared eleven OCT devices in their ability to quantify retinal layer thicknesses under different signal-strength conditions, using a commercially available phantom eye. We analyzed a medium-intensity 50 µm layer in an identical manner for all devices, using the provided log-scale images and a reconstructed linear-scale tissue reflectivity metric. Thickness measurements were highly comparable when the data were analyzed in an identical manner. With optimal signal strength, the thickness of the 50 µm layer was overestimated by a mean of 4.3 µm in the log-scale images and of 2.7 µm in the linear-scale images

Improving Visual Field Examination of the Macula Using Structural Information

Purpose: To investigate a novel approach for structure-function modeling in glaucoma to improve visual field testing in the macula. Methods: We acquired data from the macular region in 20 healthy eyes and 31 with central glaucomatous damage. Optical coherence tomography (OCT) scans were used to estimate the local macular ganglion cell density. Perimetry was performed with a fundus-tracking device using a 10-2 grid. OCT scans were matched to the retinal image from the fundus perimeter to accurately map the tested locations onto the structural damage. Binary responses from the subjects to all presented stimuli were used to calculate the structure-function model used to generate prior distributions for a ZEST (Zippy Estimation by Sequential Testing) Bayesian strategy. We used simulations based on structural and functional data acquired from an independent dataset of 20 glaucoma patients to compare the performance of this new strategy, structural macular ZEST (MacS-ZEST), with a standard ZEST. Results: Compared to the standard ZEST, MacS-ZEST reduced the number of presentations by 13% in reliable simulated subjects and 14% with higher rates (≥20%) of false positive or false negative errors. Reduction in mean absolute error was not present for reliable subjects but was gradually more important with unreliable responses (≥10% at 30% error rate). Conclusions: Binary responses can be modeled to incorporate detailed structural information from macular OCT into visual field testing, improving overall speed and accuracy in poor responders. Translational Relevance: Structural information can improve speed and reliability for macular testing in glaucoma practice

Optical Coherence Tomography Angiography of Iris Nevus: A Case Report

Iris nevus is common: 6% of patients with suspected iris melanoma have lesions other than melanoma, and 36% of them are nevi. Iris nevus turns into melanoma in approximately 8% of cases at a mean of 15 years. This case report provides the first description of an iris tumor examined with iris optical coherence tomography angiography (OCTA) compared to iris fluorescein angiography (IFA). A 60-year-old man with a diagnosis of iris nevus in the left eye was referred to our department for IFA and iris OCTA. The iris vasculature in IFA was visible only in the early phases, but not clearly. OCTA, however, gave visualization of the vascular network and very precisely defined the vessels of the whole lesion, except for the pupillary portion, which was masked by superficial pigment accumulations. IFA and iris OCTA can add information about the vascular architecture compared to slit-lamp biomicroscopy, ultrasound biomicroscopy, and anterior-segment OCT. However, IFA is time-consuming and invasive and can – very occasionally – cause serious adverse reactions. In contrast, OCTA defines the texture of the iris vasculature better. In conclusion, OCTA is a new method, easy to execute, needing no dye injection, and provides useful information on the vascular network of iris lesions. It could therefore be helpful in the diagnosis and follow-up of these lesions

Cataract and optic disk drusen in a patient with glycogenosis and di George syndrome: clinical and molecular report

Background We report the ophthalmic findings of a patient with type Ia glycogen storage disease (GSD Ia), DiGeorge syndrome (DGS), cataract and optic nerve head drusen (ONHD). Case presentation A 26-year-old white woman, born at term by natural delivery presented with a post-natal diagnosis of GSD Ia. Genetic testing by array-comparative genomic hybridization (CGH) for DGS was required because of her low levels of serum calcium. The patient has been followed from birth, attending the day-hospital every six months at the San Paolo Hospital, Milan, outpatient clinic for metabolic diseases and previously at another eye center. During the last day-hospital visit, a complete eye examination showed ONHD and cataract in both eyes. Next Generation Sequencing (NGS) was subsequently done to check for any association between the eye problems and metabolic aspects. Conclusions This is the first description of ocular changes in a patient with GSD Ia and DGS. Mutations explaining GSD Ia and DGS were found but no specific causative mutation for cataract and ONHD. The metabolic etiology of her lens changes is known, whereas the pathogenesis of ONHD is not clear. Although the presence of cataract and ONHD could be a coincidence; the case reported could suggest that hypocalcemia due to DGS could be the common biochemical pathway

Improving the Accuracy and Speed of Visual Field Testing in Glaucoma With Structural Information and Deep Learning

Purpose: To assess the performance of a perimetric strategy using structure–function predictions from a deep learning (DL) model. Methods: Visual field test–retest data from 146 eyes (75 patients) with glaucoma with (median [5th–95th percentile]) 10 [7, 10] tests per eye were used. Structure–function predictions were generated with a previously described DL model using cicumpapillary optical coherence tomography (OCT) scans. Structurally informed prior distributions were built grouping the observed measured sensitivities for each predicted value and recalculated for each subject with a leave-one-out approach. A zippy estimation by sequential testing (ZEST) strategy was used for the simulations (1000 per eye). Groundtruth sensitivities for each eye were the medians of the test–retest values. Two variations of ZEST were compared in terms of speed (average total number of presentations [NP] per eye) and accuracy (average mean absolute error [MAE] per eye), using either a combination of normal and abnormal thresholds (ZEST) or the calculated structural distributions (S-ZEST) as prior information. Two additional versions of these strategies employing spatial correlations were tested. Results: S-ZEST was significantly faster, with a mean average NP of 213.87 (SD = 28.18), than ZEST, with a mean average NP of 255.65 (SD = 50.27) (P < 0.001). The average MAE was smaller for S-ZEST (1.98; SD = 2.37) than ZEST (2.43; SD = 2.69) (P < 0.001). Spatial correlations further improved both strategies (P < 0.001), but the differences between ZEST and S-ZEST remained significant (P < 0.001). Conclusions: DL structure–function predictions can significantly improve perimetric tests. Translational Relevance: DL structure–function predictions from clinically available OCT scans can improve perimetry in glaucoma patients

Effect of prophylactic timolol 0.1% gel on intraocular pressure after an intravitreal injection of ranibizumab: a randomized study

Purpose: The purpose of this study is to make a prospective evaluation of the effect of timolol 0.1% eye gel on short-term intraocular pressure (IOP) after an intravitreal injection (IVI) of ranibizumab. Participants and methods: One hundred and fifty eyes of 150 IVI-naïve patients with macular edema caused by various pathological conditions (age-related macular degeneration, central or branch retinal vein occlusion, and diabetic retinopathy) were scheduled to undergo an IVI of ranibizumab (0.5 mg/0.05 cc). The patients were randomly divided into three groups: 50 were not treated with timolol before the IVI (group 1); 50 received an instillation of timolol 0.1% eye gel the evening before the IVI (group 2); and 50 received an instillation of timolol 0.1% eye gel 2 hours before the IVI (group 3). The incidence of clinically significant intraocular hypertensive spikes (>25 mmHg and >40 mmHg) was then assessed. Results: Our findings showed that mean IOP at baseline was significantly higher than at both 5 and 60 minutes after IVI (P25 mmHg were recorded at either time in 27 patients (54%) in group 1, 23 patients (44%) in group 2, and 24 patients (48%) in group 3. None of the between-group differences were significant. Spikes of >40 mmHg (which were only detected 5 minutes after IVI) were recorded in nine (18%), eight (16%), and one patient (2%) in groups 1, 2, and 3, respectively. The only significant difference was between the control and group 3 (P=0.012). Conclusion: An increase in IOP after antivascular endothelial growth factor IVI is a frequent complication. The prophylactic use of timolol 0.1% gel effectively reduced the mean IOP when administered 2 hours before IVI and was also effective in preventing dangerous IOP spikes of >40 mmHg. It is therefore recommended before IVIs as a means of preventing emergency procedures and preserving the health of the optic nerve

Improving the structure function relationship in the macula

The macula is the central part of the retina responsible for central vision and can suffer damage from many diseases, including diabetes, macular degeneration and glaucoma. Establishing a relationship between functional measurements, such as perimetry, and structural metrics, such as those obtained through imaging, has proven both clinically appealing and challenging, owing to specific features of this area of the retina. The programme of work presented in this thesis focuses on improving the accuracy of structure-function analyses of the macula as well as the mechanistic understanding of structure-function relationship in both healthy and diseased eyes. The first study revisits and improves previous models quantifying the length of Henle’s fibres. This directly relates to the radial displacement of Retinal Ganglion Cells (RGCs) from their photoreceptors and affects structure-function mapping. The study demonstrated the inaccuracy of previous methods used to displace perimetric stimuli, proposing a correct implementation of these calculations. These results were made available to other researchers in a user-friendly web application. The second study explored how natural positioning of observers in front of imaging and perimetry devices, as well as their fixation and eye movements, affected the precision of macular structure-function mapping. The study analysed data from an eye-tracking perimeter used to test both healthy eyes and patients with glaucoma. An optimal strategy for structure-function mapping was developed and the mapping error introduced by fixation was quantified. The third study used data from an eye-tracking perimeter and the framework of an established neural model of spatial summation to investigate the structure-function relationship in early neural loss in patients with diabetes without diabetic retinopathy, quantified with both imaging and functional tests, including Frequency Doubling Perimetry, standard visual acuity and contrast sensitivity. The fourth study involved the prospective collection of data from healthy observers with perimetric stimuli of different sizes and durations, using custom software. The data were used to develop a computational model of perimetric sensitivity able to reproduce the interaction between spatial and temporal summation in the context of cortical integration and their link to the number of retinal ganglion cells being stimulated. In the fifth study, the methodology and mechanistic framework developed in the previous studies were applied to test the computational model in glaucoma. The model was used to obtain functional estimates of retinal ganglion cell damage from standard automated perimetry data collected in glaucoma patients and healthy age-related controls. The results were correlated with imaging and histology data from previous literature