Distribution of natural radionuclides in NORM samples from North Abu Rusheid area, Egypt.

The North Abu Rusheid area in Egypt is a well-known high background natural radiation area (HBNRA) due to the existence of naturally occurring radioactive materials (NORMs) in mylonitic rocks. In this study, 27 rock samples were selected for dose estimation studies. 238U and 232Th were measured using inductively coupled plasma mass spectrometry (ICP-MS) and 40K was measured using sodium iodide (thallium) gamma-ray spectroscopy. The ranges of activity concentrations (Bq/kg) of 238U, 232Th and 40K in the samples varied from 270 ± 2 to 2120 ± 29, 350 ± 2 to 1840 ± 27 and 20 ± 2 to 1390 ± 35 with mean values of 980 ± 349, 770 ± 351, and 640 ± 402 Bq/kg, respectively. The radiological hazard parameters were estimated from activity concentrations of 238U, 232Th and 40K and compared to United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) values. The present study revealed that the hazard parameters were several times higher than the worldwide averages. The U/Th concentration ratio ranged from 0.7 to 3 and could be attributed to the presence of kasolite, uranothorite, zircon, and columbite in mylonitic rocks. From the radiological protection viewpoint, it is necessary to monitor natural radionuclides in these rocks prior to their use in residential and commercial construction materials.

Fingerprick autologous blood: a novel treatment for dry eye syndrome.

PurposeDry eye syndrome (DES) causes significant morbidity. Trials of blood-derived products in treatment of the condition show promising results. However, their production is expensive and time-consuming. We investigate fingerprick autologous blood (FAB) as an alternative low-cost, readily accessible treatment for DES.Patients and methodsProspective, non-comparative, interventional case series. In total, 29 eyes of 16 DES patients (2 males and 14 females) from two NHS sites in the United Kingdom. Patients instructed to clean a finger, prick with a blood lancet, and apply a drop of blood to the lower fornix of the affected eye(s), 4 times daily for 8 weeks then stop and review 4 weeks later. Follow-up visits occurred ~3 days, 2, 4, 8 weeks into therapy, and 4 weeks post-cessation. At each visit, visual acuity, corneal staining, Schirmer's test, tear break-up time (TBUT), and ocular comfort index (OCI) were measured, and photographs taken. Results were analysed using Student's paired t-test.ResultsAt 8 weeks, there was improvement in mean Oxford corneal staining grade (3.31 to 2.07 (P<0.0001)), TBUT (5.00 to 7.80 s (P<0.05)), visual acuity (0.08 to 0.01 LogMAR equivalent (P<0.05)), and OCI score (56.03 to 39.72 (P<0.0001)). There was no statistically significant change in Schirmer's test results. Four weeks post-cessation versus immediately after completion of FAB therapy, mean staining grade worsened from 2.07 to 2.86 (P<0.0001). OCI score worsened from 39.72 to 44.67 (P<0.05).ConclusionsIn our limited case series FAB appears to be a safe and effective treatment for DES.

Influence of medical student career aims on ophthalmic surgical simulator performance (part of the international forum for ophthalmic simulation studies).

BACKGROUND: To evaluate whether medical students who have expressed a strong desire to pursue ophthalmology as a career perform simulated ophthalmic surgical tasks to a higher level than medical students whose interests lie elsewhere. METHODS: All participants were fourth or fifth year students at University College London (UCL) Medical School, London, UK. One cohort was recruited from the Moorfields Academy, an ophthalmic forum designed to enhance collaboration and innovation within the specialty. These students were therefore seen as highly motivated, expressing a desire to pursue a career in ophthalmology. The other cohort of students was invited to participate during their fourth year UCL Ophthalmology attachment, but expressed interest in non-ophthalmic disciplines. Participants carried out a single attempt of three modules on the Eyesi Surgical Simulator, and total and mean scores were calculated out of 100. RESULTS: 13 academy and 15 non-academy students were enrolled. The overall mean scores were 51/100 for the academy group, range 0-97, and 45.5/100 for the non-academy group, range 0-90 (p=0.49). Scores for precision testing, forceps training and capsulorrhexis training for academy versus non-academy were 45.8 versus 37.8 (p=0.61), 57.1 versus 52.3 (p=0.8) and 50.2 versus 46.4 (p=0.55), respectively. CONCLUSIONS: This study is the first to suggest that medical students with a strong career interest in ophthalmology do not perform microsurgical tasks to a higher level than medical students who have no goal in this area. This also indicates variation in scores between novices, which may serve as a pitfall in the use of simulators as a tool for entry into training.

Tracking camera control in endoscopic dacryocystorhinostomy surgery.

OBJECTIVES: Poor camera control during endoscopic dacryocystorhinostomy (EnDCR) surgery can cause inadequate visualisation of the anatomy and suboptimal surgical outcomes. This study investigates the feasibility of using computer vision tracking in EnDCR surgery as a potential formative feedback tool for the quality of endoscope control. DESIGN: A prospective cohort analysis was undertaken comparing junior versus senior surgeons performing routine EnDCR surgery. Computer vision tracking was applied to endoscopic video footage of the surgery: Total number of movements, camera path length in pixels and surgical time were determined for each procedure. A Mann-Whitney U-test was used to test for a significant difference between juniors and seniors (P < 0.05). SETTING: Operating theatre. PARTICIPANTS: Ten junior surgeons (<20 completed procedures) and 10 senior surgeons (>100 completed procedures). MAIN OUTCOME MEASURES: Total number of movements of the endoscope per procedure. Path length of the endoscope per procedure. RESULTS: Twenty videos, 10 from junior surgeons and 10 from senior surgeons were analysed. Feasibility of our tracking system was demonstrated. Mean camera path lengths were significantly different at 119,329px (juniors) versus 43,697px (seniors), P ≪ 0.05. The mean number of movements was significantly different at 9134 (juniors) versus 3690 (seniors), P ≪ 0.05. These quantifiable differences demonstrate construct validity for computer vision endoscope tracking as a measure of surgical experience. CONCLUSIONS: Computer vision tracking is a potentially useful structured and objective feedback tool to assist trainees in improving endoscope control. It enables juniors to examine how their pattern of endoscope control differs from that of seniors, focusing in particular on sections where they are most divergent.

The development of a virtual reality training programme for ophthalmology: repeatability and reproducibility (part of the International Forum for Ophthalmic Simulation Studies).

PURPOSE: To evaluate the variability of performance among novice ophthalmic trainees in a range of repeated tasks using the Eyesi virtual reality (VR) simulator. METHODS: Eighteen subjects undertook three attempts of five cataract specific and generic three-dimensional tasks: continuous curvilinear capsulorhexis, cracking and chopping, cataract navigation, bimanual cataract training, anti-tremor. Scores for each attempt were out of a maximum of 100 points. A non-parametric test was used to analyse the data, where a P-value of <0.05 was considered statistically significant. RESULTS: Highly significant differences were found between the scores achieved in the first attempt and that during the second (P<0.0001) and third (P<0.0001) but not between the second and third attempt (P=0.65). There was no significant variability in the overall score between the users (P=0.1104) or in the difference between their highest and lowest score (P=0.3878). Highly significant differences between tasks were shown both in the overall score (P=0.0001) and in the difference between highest and lowest score (P=0.003). CONCLUSION: This study, which is the first to quantify reproducibility of performance in entry level trainees using a VR tool, demonstrated significant intra-novice variability. The cohort of subjects performed equally overall in the range of tasks (no inter-novice variability) but each showed that performance varies significantly with the complexity of the task when using this high-fidelity instrument.

Concentration of haemodynamic and inflammatory related cytokines in diabetic retinopathy.

AIM: There are changes in blood flow during the clinical stages of diabetic retinopathy with increasing leukostasis and secondary elaboration of cytokines. This study evaluated the vitreous concentrations of haemodynamic-related (endothelin-1 (ET-1) and nitric oxide (NO)), inflammatory and anti-inflammatory (interleukin-1 receptor antagonist, IL-1 Ra) cytokines in the diabetic patients (with nonproliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR)), compared them with those of control patients (full thickness macular hole, FTMH) and correlated to macular structural indices. METHOD: Vitreous samples from five FTMH patients representing normal controls were analysed together with the vitreous samples of 15 patients with NPDR and five with PDR. The vitreous concentrations of nitrite (total NO), ET-1, and prostacyclin was determined using ELISA kits (R&D Systems, Minneapolis, MN, USA) according to the manufacturer's instructions. A sandwich luminescent immunoassay technique was used to determine IL-1beta and IL-1 Ra concentrations. RESULTS: In the different clinical groups, there were no differences in the vitreous NO and prostacyclin concentrations. In NPDR, the median ET-1 concentration (0.7 pg/ml SD +/-0.8 pg/ml) was significantly reduced (P<0.05), compared to PDR (6.35 pg/ml SD +/-0.6 pg/ml) and FTMH (3.6 pg/ml SD +/-0.14 pg/ml). Its concentration also positively correlated with foveal thickness and macular volume (P<0.05) in patients with NPDR and macular oedema. IL-1 beta was detected in PDR, and diabetic patients demonstrated a lower concentration of the anti-inflammatory cytokine IL-1 Ra. CONCLUSION: Reduced concentrations of ET-1 in NPDR may reflect the haemodynamic changes of NPDR. The IL-1 Ra concentration suggests a change in the anti-inflammatory environment of the diabetic retina.

Digital subtraction dacryocystography and syringing in the management of epiphora.

AIM: To compare the diagnostic information provided by digital subtraction dacryocystography (DCG) and syringing of the nasolacrimal system in patients with epiphora. METHODS: Twenty-five lacrimal systems of 17 patients, who presented with unilateral or bilateral epiphora and no concurrent ocular or lid abnormality, were prospectively entered into the study. The patients initially underwent syringing by a lacrimal specialist followed by DCG. RESULTS: Anatomical obstructions were detected in 88% of systems with syringing and in 84% with DCG. The anatomical sites of obstruction varied between the two tests in 20% of lacrimal drainage systems. Additional useful information was provided by DCG in 28% of the cases, including identification of multiple sites of obstruction, the presence of dacryoliths, fistulae, and congenital malpositions of the nasolacrimal sac-duct junction. CONCLUSION: The two investigations were found to have comparable detection rates for anatomical obstructions. Syringing thus appears to be able to detect the problem in the majority of cases but DCG can help delineate unidentified factors of surgical significance in a selected subgroup of patients.

Applanation tonometry in silicone hydrogel contact lens wearers.

INTRODUCTION: Previous studies have investigated intraocular pressure (IOP) measurements through conventional soft (hydrogel) therapeutic contact lenses, and have found that an accurate IOP can be recorded in normal eyes, and in eyes with abnormal anterior segments. The IOP measurement through soft contact lenses may be affected by the water content and centre thickness of the lens. Silicone hydrogel contact lenses are now being used as therapeutic contact lenses due to their high oxygen permeability. The purpose of this study is to investigate if IOP can be accurately measured in a subject wearing a silicone hydrogel contact lens. METHODS: In a cohort study, the IOP was measured with a Goldmann applanation tonometer without a contact lens and then repeated with a hydrogel contact lens in situ. RESULTS: The IOP of 20 eyes of 10 volunteers with no ocular pathology was measured. The mean difference (+/-S.D.) found between IOP measurement with (mean 15.55+/-1.70 mmHg) and without (mean 16.05+/-1.90 mmHg) contact lens was found to be -0.5+/-0.89 mmHg. Statistical analysis was performed which revealed a correlation coefficient of 0.89. No significant statistical difference was found between the two groups with paired t-test (p=0.19). CONCLUSION: Accurate measurement of IOP by applanation tonometry can be achieved through a silicone hydrogel contact lens.

Sub-Tenon anaesthesia: reduction in subconjunctival haemorrhage with controlled bipolar conjunctival cautery.

PURPOSE: To evaluate the effect of controlled conjunctival cautery on the frequency and extent of subconjunctival haemorrhage (SCH) associated with sub-Tenon anaesthetic (STA) injection in patients with various clotting states. METHODS: One hundred forty-four patients suitable for cataract surgery with STA were prospectively divided into four groups: group A (n=36) were on warfarin (INR 1.8-4.2); group B (n=48) on aspirin (75 mg); group C (n=12) on clopidogrel (75 mg); and group D (n=48) on no anticoagulant or antiplatelet agents. All patients had no other known coagulopathy. Each group was randomly divided into two subgroups, one of which received localised bipolar cautery under microscope control to the STA conjunctival entry site before tissue dissection, whereas the other served as a control. chi(2) and Fisher's exact tests were used to analyse the data with the SPSS package (v11.0). RESULTS: Conjunctival cautery reduced the frequency of SCH from 67 to 6% in group A (P=0.0001); from 37.5 to 4% in group B (P=0.005); from 50 to 0% in group C (P=0.9); and from 17 to 0% in group D (P=0.55). This overall reduction in SCH was highly significant (P<0.0001), especially in groups A and B. No statistically significant reduction in the extent of SCH was found. CONCLUSIONS: Controlled localised bipolar conjunctival cautery before STA injection may significantly reduce the frequency of SCH, especially in patients on warfarin or aspirin.

Radiological classification of anterior skull base anatomy prior to performing medial orbital wall decompression.

PURPOSE: To study a radiological classification, originally described by Keros in 1965, which provides an objective assessment of anterior skull base anatomy relevant in patients undergoing external medial orbital decompression. MATERIALS AND METHODS: The classification is based on anatomical landmarks measured via coronal CT-scan. The patients are divided into 3 Keros categories based on their olfactory fossa depth; Keros 1 (1-3 mm), Keros 2 (4-7 mm) and Keros 3 (8-16 mm). A cross-sectional group of 32 consecutive patients on the hospital radiology database with coronal CT scans were classified according to the Keros system. RESULTS: All the patients fell into one of the three Keros categories. Anatomical associations of the Keros classification suggest that Keros 1 patients have the least risk of intracranial entry whilst Keros 3 patients carry the greatest risk. CONCLUSION: Keros classification provides an objective assessment of anterior skull base anatomy and can therefore guide the surgeon on the superior extent of medial wall bone removal during orbital decompression. This may help improve the safety profile of the procedure.

Does lesion size determine the success rate of photodynamic therapy for age-related macular degeneration?

Photodynamic therapy (PDT) is a new evidence-based treatment modality available for choroidal neovascularisation (CNV) secondary to age-related macular degeneration (AMD). Eligibility for PDT is based on the morphological classification of the neovascular complex, the benefit being greater in classic with no occult lesions. Lesion size is also shown to be a predictive factor for treatment benefit. This retrospective case series looked at effect of initial and final lesion size on the visual outcome of patients with subfoveal classic with no occult CNV and found that increasing initial and final lesion size is associated with poorer visual outcome.