Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 50
Filter
1.
Acta Neurol Belg ; 124(3): 987-993, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38546932

ABSTRACT

We aimed to investigate the diagnostic value of Optical coherence tomography (OCT) in Alzheimer's disease (AD) and to assess the correlation between OCT and fluorodeoxyglucose (FDG)-positron emission tomography (PET) which shows high diagnostic agreement with findings from postmortem histopathology-the gold standard method. Patients who were diagnosed with AD-related dementia were selected for the study. Patients with a mini mental test (MMT) score between 18 and 23 were included in the study (n = 31). Volunteers with MMT ≥ 28 and no cognitive impairment were included in the study as the control group (n = 31). OCT imaging was performed in the patient and control groups after detailed ophthalmological examinations including visual acuity and intraocular pressure measurements. Brain glucose metabolism measurement was performed using 18 F-FDG PET/computed tomography. When adjusted for age and sex, mean retinal nerve fiber layer thickness (RNFL) thickness showed a significant difference between groups and the RNFL thickness in the superior temporal and superior nasal quadrants in AD-related mild dementia group showed a significant difference (p < 0.05). Furthermore, only the RNFL thickness in the inferior nasal quadrant of the right eye showed a significant difference between the groups (p = 0.016). It is thought that OCT is a promising imaging method in the elderly population due to its low-cost, non-invasive and easily applicability, and therefore, it may contribute in the future as a tool in the periodic follow-up of patients diagnosed with AD.


Subject(s)
Alzheimer Disease , Fluorodeoxyglucose F18 , Positron-Emission Tomography , Retina , Tomography, Optical Coherence , Humans , Alzheimer Disease/diagnostic imaging , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Female , Male , Aged , Tomography, Optical Coherence/methods , Retina/diagnostic imaging , Retina/pathology , Retina/metabolism , Positron-Emission Tomography/methods , Middle Aged , Aged, 80 and over , Radiopharmaceuticals , Positron Emission Tomography Computed Tomography/methods
2.
Indian J Ophthalmol ; 72(Suppl 2): S293-S297, 2024 Feb 01.
Article in English | MEDLINE | ID: mdl-38271426

ABSTRACT

PURPOSE: To evaluate the effect of age-related macular degeneration (AMD) on vision-related quality of life (VRQOL) and depression levels. METHODS: This cross-sectional study included 143 patients who are being followed up with a diagnosis of AMD. The Turkish versions of the National Eye Institute Visual Functioning Questionnaire-25 (NEI VFQ-25) and Geriatric Depression Scale-15 (GDS-15) were directed to the patients. The questionnaire results were analyzed based on the severity, treatment procedures for AMD, and sociodemographic characteristics of patients. RESULTS: The subscale scores obtained from the NEI VFQ-25 ranged from 47.54 for "near activities" to 84.02 for "color vision." Of the patients, 59.4% (85/143) were compatible with depression according to the GDS-15 questionnaire. There was no significant difference in the NEI VFQ-25 subscale scores between the gender groups (P > 0.05), whereas females were statistically significantly more depressive than males (P < 0.05). There were no significant differences between the injection (anti-vascular endothelial growth factors [anti-VEGF]) group and the non-injection group in terms of subscales of the NEI VFQ-25 questionnaire (P > 0.05). The depression ratio in the non-injected group was statistically significantly higher (P < 0.05). CONCLUSION: According to the present study, the association between depression and AMD is a fact that should be highlighted. Patients with depression had lower scores on the quality of life (QOL) test. Previous intravitreal injection did not affect NEI VFQ-25 scores. Female patients with AMD had higher rates of depression and lower visual acuity levels.


Subject(s)
Macular Degeneration , Quality of Life , Male , Humans , Female , Aged , Cross-Sectional Studies , Depression/diagnosis , Depression/epidemiology , Depression/etiology , Macular Degeneration/complications , Macular Degeneration/diagnosis , Macular Degeneration/epidemiology , Visual Acuity , Surveys and Questionnaires
3.
Eur J Ophthalmol ; 34(1): 175-180, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37424261

ABSTRACT

PURPOSE: To investigate the relationship between serum iron status indicators (ferritin) levels and POAG. METHODS: The files of all glaucoma patients who applied to the ophthalmology clinic between January 2018 and January 2022 were reviewed retrospectively. Laboratory data from fasting blood tests, internal medicine outpatient clinic reports, and extensive ophthalmologic examination data, including fundus photographs showing the optic disc, were collected from the files. A control group was formed from individuals with adequate general and eye health, age- and gender-matched individuals who had undergone examination in the ophthalmology clinic within the same date range. Serum iron status indicators and some laboratory data of POAG patients and healthy controls were compared. RESULT: Of our participants, consisting of 65 patients with POAG and 72 healthy controls, 84 (61.32%) were female and 53 (38.68%) were male. It was observed that serum ferritin level was significantly higher in POAG patients compared to healthy controls, and the total iron binding capacity was significantly lower (respectively (p = 0.022), (p = 0.002). In logistic regression analysis, it was found that the risk of POAG increased in cases with high serum ferritin levels (OR = 0.982; p = 0.012). In addition, the risk of POAG was found to increase in cases where MCV was lower (OR = 1.121; p = 0.039). CONCLUSION: This study shows that higher serum ferritin levels are associated with a higher risk of POAG.


Subject(s)
Glaucoma, Open-Angle , Optic Disk , Humans , Male , Female , Glaucoma, Open-Angle/diagnosis , Retrospective Studies , Ferritins , Iron , Intraocular Pressure
4.
Turk J Ophthalmol ; 53(6): 343-348, 2023 12 21.
Article in English | MEDLINE | ID: mdl-38014881

ABSTRACT

Objectives: To determine the roles of small GTP-binding proteins Rac1, Rac2, and Rac3 expression in pterygial tissue and to compare these expressions with normal conjunctival tissue. Materials and Methods: Seventy-eight patients with primary pterygium were enrolled. Healthy conjunctival graft specimens obtained during pterygium surgery were used as control tissue. The real-time polymerase chain reaction method on the BioMark HD dynamic array system was utilized in genomic mRNA for the gene expression analysis. Protein expressions were analyzed using western blot and immunohistochemical methods. Results: RAC1, RAC2, and RAC3 gene expressions in pterygial tissues were not markedly elevated when compared to the control specimens (p>0.05). As a very low level of RAC1 gene expression was observed, further protein expression analysis was performed for the Rac2 and Rac3 proteins. Western blot and immunohistochemical analysis of Rac2 and Rac3 protein expression revealed no significant differences between pterygial and healthy tissues (p>0.05). Conclusion: This is the first study to identify the contribution of Rac proteins in pterygium. Our results indicate that the small GTP-binding protein Rac may not be involved in pterygium pathogenesis.


Subject(s)
Pterygium , Humans , Pterygium/surgery , Pterygium/genetics , Pterygium/metabolism , Conjunctiva/metabolism , rac GTP-Binding Proteins/genetics , rac GTP-Binding Proteins/metabolism , Blotting, Western
5.
Eye Contact Lens ; 49(11): 508-510, 2023 Nov 01.
Article in English | MEDLINE | ID: mdl-37625153

ABSTRACT

PURPOSE: To investigate the effects of coronavirus disease 2019 (COVID-19) infection on the corneal endothelium in children. METHODS: This retrospective study included 46 pediatric patients with COVID-19 infection and 38 healthy controls. Specular microscopy measurements were analyzed, and measurements were obtained from images showing at least 100 cells with clear borders. Mean endothelial cell density, mean hexagonal cell percentage (HEX), mean coefficient of variation (CV), central corneal thickness, and mean cell area were evaluated. RESULTS: Specular microscopy data showed that the CV values were 2.442±6.517 in the healthy control group (HCG) and 2.659±5.119 in the COVID-19-affected group (CAG) ( P =0.003). The hexagonality of the HCG and CAG were 6.916±8.271 and 6.683±5.885, respectively ( P =0.011). CONCLUSION: A decrease in the HEX and an increase in the CV were observed in the corneal specular microscopic examination of children with COVID-19 infection. These results are important in demonstrating the corneal effects of COVID-19 infection in children.


Subject(s)
COVID-19 , Endothelium, Corneal , Humans , Child , Retrospective Studies , Prospective Studies , Cornea , Cell Count
6.
Eye Contact Lens ; 49(7): 296-300, 2023 Jul 01.
Article in English | MEDLINE | ID: mdl-37171496

ABSTRACT

PURPOSE: To compare the effects of cooled and room temperature irrigation on the preoperative and early postoperative corneal endothelial parameter values in posterior vitrectomy. MATERIALS AND METHODS: In this prospective, randomized, comparative study, 68 patients underwent a standard 3-port, 23-G posterior vitrectomy operation by a single surgeon. Cooled irrigation solution was applied to 36 patients during surgery (group 1), and room temperature irrigation solution was applied to 32 patients (group 2). The patients were also divided into four groups according to their history of noncomplicated cataract surgery (phakic or pseudophakic) and the types of tamponade used (silicone or gas). The central corneal thickness (CCT), endothelial cell density (ECD), mean cell area (MCA), hexagonal cell percent, and coefficient of variation of cell area (CV) parameter values of the groups at preoperative and postoperative 1 month were compared. RESULTS: There were no statistically significant differences between the preoperative and postoperative corneal parameter values in groups 1 and 2 ( P >0.05). However, it was remarkable that the percentage of preoperative-postoperative change in all the corneal parameter values was higher in group 2. When the results of the subgroup analyses of the patients who were pseudophakic and used gas tamponade (Group D) in group 2 were examined, it was determined that the negative effects were significantly higher in the postoperative values for the ECD, MCA, CV, and CCT parameters compared with the preoperative values ( P <0.05). CONCLUSION: In patients with pseudophakia and gas tamponade, cooled irrigation was found to be more advantageous for corneal parameters.


Subject(s)
Endothelium, Corneal , Vitrectomy , Humans , Temperature , Prospective Studies , Cornea/surgery , Cell Count
7.
Photodiagnosis Photodyn Ther ; 42: 103549, 2023 Jun.
Article in English | MEDLINE | ID: mdl-37028691

ABSTRACT

PURPOSE: To evaluate the changes in the retinal and optic disc (OD) microcirculation in patients with Wilson's disease (WD) using optical coherence tomography angiography (OCTA). MATERIALS AND METHODS: This cross-sectional comparative study included 35 eyes of 35 WD patients (study group) and 36 eyes of 36 healthy participants (control group). The patients with WD were divided into subgroups based on the presence of Kayser-Fleischer rings. All the participants underwent a comprehensive ophthalmological examination, including OCTA. RESULTS: The inferior perifoveal deep capillary plexus vessel density (DCP-VD), inferior radial peripapillary capillary vessel density (RPC-VD), and inferior peripapillary retinal nerve fiber layer (PPRNFL) thickness were significantly lower in the WD group than in the healthy participants (p=0.041, p=0.043, and p=0.045, respectively). In addition, in the subgroup analysis, the superior RPC-VD and inferior PPRNFL were significantly lower in the subgroup with Kayser-Fleischer rings (p=0.013 and p=0.041, respectively). CONCLUSION: We showed there to be changes in certain OCTA parameters in WD patients when compared with healthy controls. Thus, we hypothesized that OCTA could detect any retinal microvascular changes in WD patients without clinical evidence of retinal or OD involvement.


Subject(s)
Hepatolenticular Degeneration , Optic Disk , Photochemotherapy , Humans , Optic Disk/diagnostic imaging , Optic Disk/blood supply , Fluorescein Angiography/methods , Retinal Vessels/diagnostic imaging , Tomography, Optical Coherence/methods , Cross-Sectional Studies , Hepatolenticular Degeneration/diagnostic imaging , Photochemotherapy/methods , Photosensitizing Agents , Choroid , Copper
8.
Int Ophthalmol ; 43(7): 2301-2306, 2023 Jul.
Article in English | MEDLINE | ID: mdl-36595126

ABSTRACT

PURPOSE: To evaluate the ocular findings and the relationship between these findings and the disease severity of patients with Fabry disease (FD) in South-East Anatolia. METHODS: We enrolled the 24 eyes of 24 patients with FD and the disease severity scores were obtained with FD severity scoring system (DS3). The relationship between the presence of any ocular findings and DS3 scores was evaluated. RESULTS: The mean age of the patients was 35.2 ± 8.6 years. The mean DS3 score and α-galactosidase A enzyme activity of the patients was 7.04 ± 3.71 and 1.93 ± 0.84 µmol/l/h, respectively. Of the 24 patients, 20 (83.3%) had cornea verticillate (CV), 18 (75%) had tortuous conjunctival vessels, 15 (62.5%) had tortuous retinal vessels and 3 (12.5%) had lens opacities. The ocular vascular abnormalities were associated with disease severity (p < 0.05); however, the presence of CV did not affect the DS3 scores (p > 0.05). CONCLUSIONS: According to our study, the patients with ocular vascular abnormalities associated with FD had more severe disease than those who did not have an abnormality. CV was the most common ocular finding in FD, but it has no association with disease severity.


Subject(s)
Cataract , Fabry Disease , Humans , Adult , Fabry Disease/complications , Fabry Disease/diagnosis , Fabry Disease/epidemiology , Turkey/epidemiology , alpha-Galactosidase , Cataract/complications , Patient Acuity
9.
Adv Mater ; 35(9): e2206613, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36528387

ABSTRACT

Laser diodes based on solution-processable materials can benefit numerous technologies including integrated electronics and photonics, telecommunications, and medical diagnostics. An attractive system for implementing these devices is colloidal semiconductor quantum dots (QDs). The progress towards a QD laser diode has been hampered by rapid nonradiative Auger decay of optical-gain-active multicarrier states, fast device degradation at high current densities required for laser action, and unfavorable competition between optical gain and optical losses in a multicomponent device stack. Here we resolve some of these challenges and demonstrate optically excited lasing from fully functional high-current density electroluminescent (EL) devices with an integrated optical resonator. This advance has become possible due to excellent optical gain properties of continuously graded QDs and a refined device architecture, which allows for highly efficient light amplification in a thin, EL-active QD layer.

10.
Eur J Ophthalmol ; 33(1): 398-407, 2023 Jan.
Article in English | MEDLINE | ID: mdl-35924358

ABSTRACT

PURPOSE: To provide consensus on the clinical use of intravitreal dexamethasone (DEX) implant for the treatment of diabetic macular edema (DME) in Turkey. METHODS: A panel of 22 retina experts prepared 77 statements of recommendation, and 80 retinal specialists practicing in Turkey were chosen to vote either in support or against each one. A Delphi-based method was used through which the ophthalmologists were able to view all of the results anonymously after two rounds and modify their subsequent answers. The survey was conducted via a mini website, and statements without consensus were resent to the specialists with the latest vote results a week later. RESULTS: A total of 72 ophthalmologists answered the first and second round questions. After the first stage, consensus was achieved on 55 of the statements, leaving 22 without agreement. After the second stage, consensus was reached on 11 of the remaining statements. Strong consensus was achieved on statements regarding the etiopathogenesis of DME and the first-line indications and safety of the DEX implant procedure. The panel recommended the use of DEX implant for patients with an arterial thromboembolic event in the last three months and also agreed that pro re nata DEX implant treatment not only provides better outcomes for DME patients but also reduces the treatment burden for those who could not receive an adequate number of anti-vascular endothelial growth factor (VEGF) injections. CONCLUSION: This study provides clinical consensus and recommendations about the use of DEX implant in the clinical practice of DME management in Turkey.


Subject(s)
Diabetes Mellitus , Diabetic Retinopathy , Macular Edema , Humans , Macular Edema/diagnosis , Macular Edema/drug therapy , Macular Edema/etiology , Dexamethasone , Angiogenesis Inhibitors/therapeutic use , Delphi Technique , Turkey , Vascular Endothelial Growth Factor A , Drug Implants/therapeutic use , Intravitreal Injections , Glucocorticoids , Treatment Outcome , Diabetes Mellitus/drug therapy
11.
Retina ; 42(10): 1931-1938, 2022 10 01.
Article in English | MEDLINE | ID: mdl-36129266

ABSTRACT

PURPOSE: To investigate the changes in the microvascular structure of the retina and optic disk by comparing the optical coherence tomography angiography findings in preeclamptic patients with those in healthy pregnant women and healthy nonpregnant women and also to evaluate the preeclamptic patients after delivery by showing whether the changes are permanent or not. METHODS: Fifty preeclamptic, 50 healthy pregnant, and 50 healthy nonpregnant women enrolled in three groups (preeclamptic pregnant women group, healthy pregnant women group, and nonpregnant women group; respectively). Patients in the preeclamptic pregnant women group were evaluated at three different time points including up to 3 hours before delivery (Group 1), 2, or 3 days after delivery (Group 2), and 6 weeks after delivery (Group 3), and compared with each other. All patients underwent a comprehensive ophthalmologic examination including optical coherence tomography angiography. RESULTS: Choriocapillaris blood flow area, deep foveal density, deep temporal density, deep nasal density, and radial peripapillary capillary inside disk density values were significantly lower in the preeclamptic pregnant women group than in the healthy pregnant women group. Deep foveal density and deep nasal density values were significantly higher in Group 3 than in Group 1 and 2, and deep temporal density was significantly higher in Group 3 than in Group 1. CONCLUSION: Optical coherence tomography angiography diagnosed decreased deep retinal capillary density values in the macula of patients with preeclampsia, but these results improved after delivery.


Subject(s)
Macula Lutea , Optic Disk , Pre-Eclampsia , Female , Fluorescein Angiography/methods , Humans , Macula Lutea/blood supply , Optic Disk/blood supply , Pre-Eclampsia/diagnosis , Pregnancy , Retinal Vessels/physiology , Tomography, Optical Coherence/methods
12.
Eur J Ophthalmol ; 32(6): 3592-3598, 2022 Nov.
Article in English | MEDLINE | ID: mdl-35088606

ABSTRACT

PURPOSE: To compare serum vitamin D (25(OH)D) levels according to the presence of diabetic macular edema (DME) in Diabetes Mellitus (DM) patients with different retinopathy conditions. METHODS: The files of all DM patients presenting for examination at the ophthalmology clinic between October 2018 and March 2020 were retrospectively examined. Data was collected from the files and included a comprehensive ophthalmological examination, laboratory results from fasting blood tests, and the internal medicine outpatient clinic examination. Patients were divided into two groups according to the presence of DME, they were divided into three groups in terms of retinopathy and DME, and in terms of retinopathy severity and presence of DME, they were divided into five groups. RESULT: Ninety one (51.1%) of the age-sex matched participants were female and 87 (48.9%) were male. There was a statistically significant difference in vitamin D levels between the group with DME and the group without DME (p ≤ 0.001). In the comparison made according to the presence of retinopathy and DME; a significant difference was found between the DME group and the group with retinopathy but no DME (p ≤ 0.001). When the severity of retinopathy and the presence of DME were evaluated, a significant difference was found between the proliferative diabetic retinopathy (PDR) group with DME and the PDR group without DME in terms of vitamin D levels (p = 0.004). CONCLUSION: Our study shows that the presence of DME is associated with lower serum 25(OH)D levels.


Subject(s)
Diabetes Mellitus, Type 2 , Diabetic Retinopathy , Macular Edema , Diabetes Mellitus, Type 2/complications , Diabetic Retinopathy/complications , Diabetic Retinopathy/diagnosis , Female , Humans , Macular Edema/diagnosis , Macular Edema/etiology , Male , Retrospective Studies , Vitamin D
13.
Can J Ophthalmol ; 57(3): 195-200, 2022 06.
Article in English | MEDLINE | ID: mdl-33887261

ABSTRACT

OBJECTIVE: The aim of this study was to evaluate the incidence, severity, and treatment modalities of retinopathy of prematurity (ROP) in moderate and late preterm infants with a gestational age (GA) >31 + 6 weeks. METHODS: ROP screening results of preterm infants with GA >31 + 6 weeks to 36 + 6 weeks between March 2013 and January 2019 were evaluated retrospectively. Infants were divided into 2 groups according to GA as 32-33 + 6 weeks (moderate preterm) and 34-36 + 6 weeks (late preterm). In these groups, any ROP and severe ROP (requiring treatment) development rates and ROP types and treatment modalities were evaluated. RESULTS: A total of 4156 preterm infants, 1875 (45.1%) female and 2281 (54.9%) male, were included. Overall, 1466 (35.2%) of the infants were moderate preterm and 2690 (64.8%) were late preterm. The incidences of any ROP and severe ROP were 22% and 2.5%, respectively. The rate of severe ROP was 5.3% in moderate preterm infants and 0.9% in late preterm infants. Significant correlations were determined between duration of hospital stay, birth weight (BW), and GA with ROP development (r = +0.415, r = -0.258, r = -0.199, respectively; p < 0.001 for all). Of 102 patients (2.5%) requiring treatment, 64 (62.7%) had laser, 34 (33.3%) had intravitreal bevacizumab (IVB), 2 (1.9%) had sequential IVB and laser, and 2 (1.9%) had vitreoretinal surgery. CONCLUSION: ROP seems to still be an important health problem in moderate and late preterm infants in our country according to data from screening high-risk preterm infants with a GA >31 + 6 weeks. In this cohort, ROP development correlates with GA, BW, and duration of hospitalization significantly.


Subject(s)
Retinopathy of Prematurity , Bevacizumab , Birth Weight , Female , Gestational Age , Humans , Incidence , Infant , Infant, Newborn , Infant, Premature , Male , Retinopathy of Prematurity/diagnosis , Retinopathy of Prematurity/epidemiology , Retinopathy of Prematurity/therapy , Retrospective Studies , Risk Factors
14.
Curr Eye Res ; 47(1): 69-78, 2022 01.
Article in English | MEDLINE | ID: mdl-34252337

ABSTRACT

PURPOSE/AIM OF THE STUDY: Researchers have investigated glaucoma drainage devices in various in vitro experimental setups to overcome their disadvantages. In this study, it is aimed to perform in vitro analyses of glaucoma drainage devices that are actively utilized for glaucoma treatment. MATERIALS AND METHODS: A new in vitro experimental setup is constructed and the first outcomes of numerical simulations and experimental trials are shared. Firstly, an in vitro experimental setup is designed and simulated in ANSYS Fluent, then assembled/fabricated using microfluidic equipment. Secondly, computational fluid dynamics results are expressed as pressure losses through an Ahmed Valve implant, a Molteno drainage device, an Ex-Press implant for physiological flow rates. RESULTS: In the scope of this study, Ahmed Valve (valved), Molteno (non-valved), Ex-Press (orbital shunt) implants are examined numerically using computational fluid dynamics tools. Results are compared with in vitro studies of the proposed experimental setup. Poiseuille and Reynolds numbers versus pressure drop characteristics of tested glaucoma drainage devices are also obtained using in vitro microfluidic experimental setup. In the range of 1.6-2.5 µl/min, Ahmed Valve implant created an active and effective pressure drop of 5.6 to 12 mmHg. Ahmed Valve and Molteno showed similar characteristics in terms of Poiseuille and Reynolds numbers variations with pressure drop across implants. Ex-Press, opposing Molteno and Ahmed Valve gave a reciprocal correlation between pressure drop and Po. CONCLUSIONS: High resemblances of pressure drops between computational fluid dynamics results and in vitro microfluidic experimental results proved that the setup will be a better choice compared to syringe pump type setups for testing different glaucoma drainage devices at the same conditions. In conclusion, a new glaucoma drainage device should be equipped with a slimmer but larger end plate and a valve mechanism similar to Ahmed Valve in the perspective of intraocular pressure drop performance.


Subject(s)
Glaucoma Drainage Implants , Glaucoma/surgery , Intraocular Pressure/physiology , Microfluidics/methods , Models, Biological , Follow-Up Studies , Glaucoma/physiopathology , Humans , Tonometry, Ocular
15.
ACS Nano ; 13(9): 10662-10670, 2019 Sep 24.
Article in English | MEDLINE | ID: mdl-31436957

ABSTRACT

As an attractive materials system for high-performance optoelectronics, colloidal nanoplatelets (NPLs) benefit from atomic-level precision in thickness, minimizing emission inhomogeneous broadening. Much progress has been made to enhance their photoluminescence quantum yield (PLQY) and photostability. However, to date, layer-by-layer growth of shells at room temperature has resulted in defects that limit PLQY and thus curtail the performance of NPLs as an optical gain medium. Here, we introduce a hot-injection method growing giant alloyed shells using an approach that reduces core/shell lattice mismatch and suppresses Auger recombination. Near-unity PLQY is achieved with a narrow full-width-at-half-maximum (20 nm), accompanied by emission tunability (from 610 to 650 nm). The biexciton lifetime exceeds 1 ns, an order of magnitude longer than in conventional colloidal quantum dots (CQDs). Reduced Auger recombination enables record-low amplified spontaneous emission threshold of 2.4 µJ cm-2 under one-photon pumping. This is lower by a factor of 2.5 than the best previously reported value in nanocrystals (6 µJ cm-2 for CdSe/CdS NPLs). Here, we also report single-mode lasing operation with a 0.55 mJ cm-2 threshold under two-photoexcitation, which is also the best among nanocrystals (compared to 0.76 mJ cm-2 from CdSe/CdS CQDs in the Fabry-Pérot cavity). These findings indicate that hot-injection growth of thick alloyed shells makes ultrahigh performance NPLs.

16.
Nano Lett ; 19(7): 4297-4305, 2019 07 10.
Article in English | MEDLINE | ID: mdl-31185570

ABSTRACT

We proposed and showed strongly orientation-controlled Förster resonance energy transfer (FRET) to highly anisotropic CdSe nanoplatelets (NPLs). For this purpose, we developed a liquid-air interface self-assembly technique specific to depositing a complete monolayer of NPLs only in a single desired orientation, either fully stacked (edge-up) or fully nonstacked (face-down), with near-unity surface coverage and across large areas over 20 cm2. These NPL monolayers were employed as acceptors in an energy transfer working model system to pair with CdZnS/ZnS core/shell quantum dots (QDs) as donors. We found the resulting energy transfer from the QDs to be significantly accelerated (by up to 50%) to the edge-up NPL monolayer compared to the face-down one. We revealed that this acceleration of FRET is accounted for by the enhancement of the dipole-dipole interaction factor between a QD-NPL pair (increased from 1/3 to 5/6) as well as the closer packing of NPLs with stacking. Also systematically studying the distance-dependence of FRET between QDs and NPL monolayers via varying their separation (d) with a dielectric spacer, we found out that the FRET rate scales with d-4 regardless of the specific NPL orientation. Our FRET model, which is based on the original Förster theory, computes the FRET efficiencies in excellent agreement with our experimental results and explains well the enhancement of FRET to NPLs with stacking. These findings indicate that the geometrical orientation of NPLs and thereby their dipole interaction strength can be exploited as an additional degree of freedom to control and tune the energy transfer rate.

17.
Indian J Ophthalmol ; 67(6): 811-815, 2019 06.
Article in English | MEDLINE | ID: mdl-31124492

ABSTRACT

Purpose: More than 3.5 million Syrians came to Turkey seeking refuge and over 470,000 Syrian infants were born since the start of the civil war in 2011. Our aim is to compare the incidence of retinopathy of prematurity (ROP) between Syrian refugees and Turkish citizens. Methods: This multicenter, retrospective study was conducted in Gaziantep University, Faculty of Medicine and Gaziantep Children's Hospital in Turkey. We included the data of patients who were screened for ROP between July 2015 and June 2017. Results: The above-mentioned data of 906 Turkish infants and 199 Syrian infants were included in this study. Mean gestational ages (GAs) were (32.9 ± 2.7) and (32.1 ± 2.8) weeks as well as mean birth weights (BWs) were (1937.5 ± 582.9) and (1696.8 ± 485.5) g, in Turkish and Syrian infants, respectively. GA and BW were significantly lower in Syrian infants while time spent in neonatal intensive care unit was significantly higher. The zone of ROP was lower in the Syrian infants in the first examination and for the most advanced ROP (P = 0.001). Any stage ROP was present in 392 (43.3%) and 81 (40.7%) patients in Turkish and Syrian population, respectively (P = 0.490). The number of patients who required treatment for ROP were 95 (10.5%) and 20 (10.1%) in Turkish and Syrian groups, respectively (P = 0.882). Conclusion: Our findings showed that refugee infants had lower BW and GA than native population but the incidence of ROP did not differ between them. Psychosocial stress is an important risk factor for women at reproductive age as it increases the incidence of prematurity. Additional care and psychological support must be given to refugees during perinatal period to decrease the risk of premature birth.


Subject(s)
Refugees , Retinopathy of Prematurity/ethnology , Female , Gestational Age , Humans , Incidence , Infant, Newborn , Male , Neonatal Screening , Ophthalmoscopy , Prognosis , Retinopathy of Prematurity/diagnosis , Retrospective Studies , Risk Factors , Syria/ethnology , Turkey/epidemiology , Vision Screening
18.
Small ; 15(8): e1804854, 2019 Feb.
Article in English | MEDLINE | ID: mdl-30701687

ABSTRACT

Colloidal semiconductor nanoplatelets (NPLs) offer important benefits in nanocrystal optoelectronics with their unique excitonic properties. For NPLs, colloidal atomic layer deposition (c-ALD) provides the ability to produce their core/shell heterostructures. However, as c-ALD takes place at room temperature, this technique allows for only limited stability and low quantum yield. Here, highly stable, near-unity efficiency CdSe/ZnS NPLs are shown using hot-injection (HI) shell growth performed at 573 K, enabling routinely reproducible quantum yields up to 98%. These CdSe/ZnS HI-shell hetero-NPLs fully recover their initial photoluminescence (PL) intensity in solution after a heating cycle from 300 to 525 K under inert gas atmosphere, and their solid films exhibit 100% recovery of their initial PL intensity after a heating cycle up to 400 K under ambient atmosphere, by far outperforming the control group of c-ALD shell-coated CdSe/ZnS NPLs, which can sustain only 20% of their PL. In optical gain measurements, these core/HI-shell NPLs exhibit ultralow gain thresholds reaching ≈7 µJ cm-2 . Despite being annealed at 500 K, these ZnS-HI-shell NPLs possess low gain thresholds as small as 25 µJ cm-2 . These findings indicate that the proposed 573 K HI-shell-grown CdSe/ZnS NPLs hold great promise for extraordinarily high performance in nanocrystal optoelectronics.

19.
Curr Eye Res ; 44(6): 645-650, 2019 06.
Article in English | MEDLINE | ID: mdl-30657707

ABSTRACT

Purpose: Pterygium, one of the most common ocular surface diseases, is characterized by inflammatory infiltrates, proliferation, angiogenesis, fibrosis, and extracellular matrix breakdown. The objective of this study was to elucidate the levels of the intercellular adhesion molecule (ICAM)-2, and ICAM-3 gene and protein expressions in pterygium. Methods: A total of 59 patients with pterygium were included in this study. mRNA from pterygial and conjunctival autograft tissues were extracted, and real-time polymerase chain reaction on the BioMark HD dynamic array system was performed for the ICAM-2 and ICAM-3 gene expressions. ICAM-2 and ICAM-3 protein expressions using western blot and immunohistochemistry methods were also investigated in pterygial and conjunctival autograft tissues. Results: ICAM-2 and ICAM-3 gene expressions were markedly augmented in pterygial tissues (P = 0.0018 and P = 0.0023, respectively). Significant increases in protein expressions in pterygial tissues were also detected for ICAM-2 and ICAM-3 (P = 0.0116 and P = 0.0252, respectively). In the immunohistochemical studies, there was a marked increase in ICAM-3 (P = 0.0152), but not in ICAM-2 (P = 0.1041), protein expressions in pterygial tissues. Significant positive correlations between pterygia grading with ICAM-2 protein expression (P = 0.0398) and ICAM-3 immunohistochemical scores (P = 0.0138) were observed. Conclusion: These results demonstrate, for the first time, the expressions of ICAM-2 and ICAM-3 in the pterygium. These findings may help to understand the signal transduction mechanisms in the pterygium formation and provide a new therapy strategy for pterygium treatment.


Subject(s)
Antigens, CD/genetics , Cell Adhesion Molecules/genetics , Gene Expression Regulation/physiology , Pterygium/metabolism , Adult , Aged , Antigens, CD/metabolism , Biomarkers/metabolism , Blotting, Western , Cell Adhesion Molecules/metabolism , Female , Humans , Immunohistochemistry , Male , Middle Aged , RNA, Messenger/genetics , Real-Time Polymerase Chain Reaction , Young Adult
20.
Arq Bras Oftalmol ; 81(4): 302-309, 2018.
Article in English | MEDLINE | ID: mdl-29995122

ABSTRACT

PURPOSE: Scleral fixation surgery is a pivotal procedure that depends on the availability of robust and innovative surgical fixation methods. There continues to be a need for innovation in suture fixation techniques, particularly for intraocular lens implantation. METHODS: We conceived and designed a "knot ball" scleral fixation technique for suture burial in a retrospective sample of 108 patients with primary (n=40) or secondary (n=68) scleral-fixated intraocular lens. Importantly, our technique did not require additional scleral flap or tunnel procedures. We evaluated pre- and postoperative best-corrected visual aquity (BCVA) and postoperative complications. All data were analyzed and compared between groups. RESULTS: The preoperative mean BCVA improved significantly in both groups using the "knot ball" fixation technique (p<0.01). The extent of the improvement in the best-corrected visual acuity and late complications one month post-surgery were not significantly different between the groups (p>0.05). These clinical outcomes were consistent with those described in the ophthalmology literature. CONCLUSION: A "knot ball" scleral fixation technique is reported; to the best of our knowledge, this is the first report of such a technique, which offers a less invasive and simplified surgical procedure for transscleral fixation of scleral-fixated intraocular lenses. Moreover, the technique appears to display similar effectiveness and safety compared with existing scleral fixation techniques. We suggest that the "knot ball" technique warrants further research focus and clinical evaluation in future studies.


Subject(s)
Lens Implantation, Intraocular/methods , Scleral Diseases/surgery , Suture Techniques , Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Female , Humans , Male , Middle Aged , Retrospective Studies , Treatment Outcome , Visual Acuity , Young Adult
SELECTION OF CITATIONS
SEARCH DETAIL
...