Contrast sensitivity evaluation following mono- and bifocal IOL implantation

Purpose. To perform a comparative analysis of contrast sensitivity and glare sensitivity in patients implanted with mono- and bifocal IOLs. Material and methods. 60 patients (60 eyes) were examined: 30 cataract patients who underwent cataract phacoemulsification with bifocal IOL Lentis Comfort implantation; and 30 cataract patients who underwent cataract phacoemulsification with monofocal IOL Acrysof IQ implantation. In the post-operative period the examination of twilight vision and bright light sensitivity was carried out using a Binoptometer 4P visual function analyzer. Results. In patient of group I without flare with a contrast 1:23, the threshold value was achieved in 97.4% of patients, with a contrast 1:5 – in 87.6%; with a contrast 1:2.7 – in 49.2%; with a contrast 1:2 – in 38.3%; with flare and contrast 1:23 – in 90.3%; with flare and contrast 1:5 – in 84.8%; with flare and contrast 1:2.7 – in 41.2%; with flare and contrast 1:2 – in 22.8%. In patients of group II: without flare and with contrast 1:23 – in 98.6%; with a contrast 1:5 – in 90.1%; with a contrast 1:1.27 – in 61.9%, with a contrast – 1:2 – 44.5%; with flare and contrast 1:23 – in 95.6%; with flare and contrast 1:5 – in 86.9%; with flare and contrast 1:2.7 – in 48.7%; with flare and contrast 1:2 – in 40.5% Conclusions. In mesopic conditions IOL Acrysof IQ provides higher visual acuity in low contrast conditions with a slight decrease under flare conditions in comparison with IOL Lentis Comfort. Key words: contrast sensitivity, cataract phacoemulsification, bifocal IOL.

Establishment of reference intervals for Platelet Function Analyzer -100 closure time in Algerian adults

Introduction The Platelet Function Analyzer-100 (PFA-100) is a point of care instrument that simulates plug formation under high shear flow. The PFA-100 measures the time required to occlude the aperture in a biochemically active cartridge and is expressed in a term of closure time (CT). In Algeria, the reference values used in clinical laboratories are of Western origin. However, ethnic, genetic, dietary environmental, and diet differences between populations may affect reference intervals. We established the reference intervals of PFA-100 closure times in healthy Algerian adults according to the International Federation of Clinical Chemistry method, and we compared them with those of Western and Asian countries. Material and methods We enrolled 303 healthy blood donors in the study. 218 subjects met inclusion criteria. We analyzed the blood sample on the PFA-100 for CT with both the collagen epinephrine and collagen ADP cartridges. Results The reference intervals of PFA-100 collagen epinephrine CT and PFA-100 collagen ADP CT were 91–207 seconds and 71–144 seconds, respectively. Compared to Western and Asian populations, there were significant differences. The upper limits of CTs were higher for Algerians in this study. Our findings show that many healthy Algerians would be incorrectly identified as having a primary hemostasis abnormality according to the reference intervals of the manufacturer and scientific literature. Conclusion This report provides the first reference intervals for PFA-100 CTs in healthy Algerian adults. These results improve the accuracy of diagnosis and patient care in Algeria.

Utility of the Platelet Function Analyzer in Patients with Suspected Platelet Function Disorders: Diagnostic Accuracy Study

Introduction The platelet function analyzer (PFA) is widely used as a screening tool for bleeding disorders in various settings. The diagnostic performance regarding platelet function disorders (PFDs), which are among the most common inherited bleeding disorders, is however still elusive. We aimed to assess the diagnostic value of PFA for PFD in clinical practice. Methods Comprehensive clinical and laboratory data of all consecutive patients referred to a specialized outpatient between January 2012 and March 2017 with a suspected bleeding disorder were prospectively recorded. The diagnostic work-up was performed according to a prespecified protocol following current guidelines and platelet function was tested using light transmission aggregometry as well as flow cytometry. Results Five hundred and fifty-five patients were included (median age 43.7 years; interquartile range [IQR] 29.3, 61.7; 66.9% female). Possible PFD was diagnosed in 64 patients (11.5%) and confirmed PFD in 54 patients (9.7%). In patients with confirmed PFD, median closure times were 107 seconds (ADP or adenosine diphosphate; IQR 89, 130) and 169 seconds (EPI; IQR 121, 211). In patients without bleeding disorders, PFA closure times were 96 seconds (ADP; IQR 83, 109) and 137 seconds (EPI; IQR 116, 158). The sensitivity was 19.5% in case of PFA ADP (95%CI 12.6, 30.0; specificity 86.4%; 95% CI 82.4, 89.8), and 44.3% in case of PFA EPI (95% CI 34.9, 53.9; specificity 75.6%; 95% CI 70.8, 79.9). Conclusion The diagnostic performance of PFA for PFD was moderate to poor. Our results do not support the utilization of PFA for screening of PFD in clinical practice.

Prevalence of Coagulation Factors Deficiency among Young Adults in Saudi Arabia: A National Survey

Introduction Inherited bleeding disorders vary in prevalence due to genetic disparity and ethnicity. Little is known about the prevalence of coagulation factor deficiency and bleeding disorders in middle-eastern population. Methods Young Saudi adults with at least one positive bleeding symptom reported in semi-structured validated condensed MCMDM-1vWD questionnaire were tested for complete blood count, routine and special coagulation tests, serum ferritin level, and capillary zone electrophoresis. After initial testing, those with prolonged prothrombin time (PT) or activated prothrombin time (APTT) had further testing to evaluate coagulation factors level. Platelet function was tested through platelet function analyzer (PFA)-100, and multiplate aggregometer (MEA) on patients suspected of having platelet disorders. Results Six-hundred-forty patients (male = 347, 54.2%) were included. A possible platelet function defect was diagnosed in three patients with one matching Glanzmann's thrombasthenia trait pattern, and one that of Bernard-Soulier trait pattern. One patient was diagnosed with von Willebrand disease. Deficiencies in coagulation factor levels were revealed as F-VIII in 14 (7.4%), F-IX in 15 (7.6%), F-II in two (3.3%), F-V in 17 (26.1%), FVII in two (3.1%), and F-X in one (1.8%) of study subjects; low vWF activity (<50%) was found in 14 (8%). Abnormal values were found for various laboratory tests with prolongation of platelet function analyzer-epinephrine (PFA-EPI) in 11%, PFA-ADP or arachidonic acid in 15.2%, PT in 35.9%, and APTT in 63.7%. Five-hundred-seventy-six patients (90%) had normal results in the coagulation factor assays and were categorized as patients with bleeding of unknown cause (BUC). A diagnosis of a bleeding disorder was more frequently made in men than in women (38 vs. 26). Iron deficiency anemia was found in 18 (25%) females positively associated with F-IX deficiency (p-value 0.000). Male gender (73.3%, p = 0.007) was independently associated with the diagnosis of coagulation factor deficiency. Conclusion The current study reports a higher prevalence of coagulation factors deficiency in Saudi population than reported in the western population.

Comparison of acetylsalicylic acid and clopidogrel non-responsiveness assessed by light transmittance aggregometry and PFA-100® in patients undergoing neuroendovascular procedures

ObjectivesDual platelet inhibition is commonly used for prevention of cardiovascular events in patients undergoing neuroendovascular procedures. Non-responsiveness to platelet inhibitors may be associated with adverse outcomes. The aim of this study was to evaluate the reliability of the platelet function analyzer PFA-100® in comparison to light transmittance aggregometry (LTA) for monitoring clopidogrel and acetylsalicylic acid (ASA) non-responsiveness in a cohort of patients treated for intracranial aneurysm or cranial artery stenosis.MethodsNon-responsiveness to clopidogrel and ASA was assessed by LTA using adenosine diphosphate (ADP) and arachidonic acid and by PFA-100® with the ADP/prostaglandin E1 (PGE1) and collagen/epinephrine cartridges, respectively.ResultsA total of 203 patients (145 females; median age, 57 years) were analyzed. Agreement between the two tests was poor for clopidogrel non-responsiveness (ƙ=0.19) and not better than chance for ASA non-responsiveness (ƙ=0.01). Clopidogrel non-responsiveness by LTA and PFA-100® was associated with higher von Willebrand factor antigen and activity levels. ADP-induced platelet disaggregation was lower in patients with clopidogrel non-responsiveness as assessed by PFA-100®. Clopidogrel non-responsiveness by LTA was associated with a higher prevalence of diabetes and a higher body mass index (BMI). Adverse outcomes (death, thromboembolism, or in-stent thrombosis) occurred in 13% (n=26) of all patients independently of ASA and clopidogrel non-responsiveness as assessed by both devices.ConclusionsOur results show that LTA and PFA-100® are not interchangeable in the assessment of ASA and clopidogrel non-responsiveness in patients undergoing neuroendovascular interventions.

In Vitro Closure Times (PFA-100) Are Different Between Peritoneal Dialysis and Hemodialysis

Introduction Platelet dysfunction is not uncommon in patients with end-stage renal disease (ESRD). Type of renal replacement therapy may have an effect on platelet functions, which has not been well investigated. We evaluated in vitro closure time (CT) differences between peritoneal dialysis (PD) and hemodialysis (HD) patients using platelet function analyzer (PFA-100)and observed a significant difference between these renal replacement therapies. Methods Patients with ESRD undergoing PD (n = 24) or HD (n = 23) for more than 6 months were included. Blood samples for collagen/epinephrine (Col/EPI) and collagen/adenosine diphosphate (Col/ADP) measurements were obtained before HD at a mid-week session for HD patients and at an outpatient control time for PD patients. Results Three of 24 (12.5%) PD patients and 16 of 23 (69.5%) HD patients had prolonged PFA-100 Col/EPI, p< 0.001. Likewise, 4.2% of PD patients and 87.0% of HD patients had prolonged PFA-100 Col/ADP, p< 0.001. Moreover, the median times of PFA-Col/EPI and PFA-100 Col/ADP were significantly lower in PD patients compared with those of HD patients (p< 0.001). Multivariate analysis showed that the type of renal replacement was a risk factor for both elevated PFA-100 Col/ADP and PFA-100 Col/EPI after adjusted for platelets, hematocrit, and urea (p< 0.001). Conclusions The type of renal replacement therapy may have an effect on in vitro CTs; therefore, studies including more patients with long-term follow-up are needed to investigate if the difference has any impact on clinical outcomes.

Platelet function in cats with hyperthyroidism

Objectives Cats with hyperthyroidism have been reported to develop thromboembolism, with and without echocardiographic abnormalities consistent with hyperthyroidism. The objective of this study was to compare platelet function in cats with hyperthyroidism with euthyroid age-matched cats. We hypothesized that cats with hyperthyroidism have shortened collagen and adenosine diphosphate (C-ADP) closure times as measured with the platelet function analyzer (PFA-100) in comparison with healthy, age-matched controls. Methods Sixteen hyperthyroid and nine euthyroid healthy cats >7 years of age were recruited from the hospital population. Platelet function, measured using the C-ADP closure times by the PFA-100, and platelet count were measured in healthy euthyroid cats and cats with hyperthyroidism. Results Mean ± SD closure times were not significantly different between control (66.3 ± 9.6 s) and hyperthyroid cats (65.9 ± 11.5 s; P = 0.75). The mean ± SD closure times of hyperthyroid cats that either were untreated or received methimazole for ⩽3 weeks (n = 6; mean 68.5 ± 15.4 s) was not different than that of cats treated for >3 weeks (n = 10; mean 64.3 ± 8.9 s; P = 0.57). The mean automated platelet count was higher in the hyperthyroid group than in the control group ( P = 0.023). Conclusions and relevance Platelet function, as measured by closure time under high shear conditions using C-ADP as an agonist, was not affected by hyperthyroidism in this group of cats. Further research is needed to determine if a hypercoagulable state exists in hyperthyroid cats and the potential roles platelets and von Willebrand factor may have.