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Biomedical subjects

Adnan Tufail

Publications and source records attributed to Adnan Tufail.

10 recordsLinked to original sources
PubMed2026

Large-scale multiethnic electronic health record resource for diabetes complications research: the North West London Diabetes Cohort (NWLDC) - cohort profile.

PURPOSE: The North West London Diabetes Cohort is established to provide systematic characterisation of a large diabetes population as a foundation for complications research and prognostic modelling. Many predictive modelling studies neglect the essential descriptive characterisation of underlying cohorts, focusing narrowly on model accuracy. This cohort profile addresses this gap by comprehensively describing the demographic composition, clinical characteristics and complication incidence patterns. The notably diverse, multiethnic population enables examination of ethnic disparities and supports future development of reliable prognostic models and evidence-based prevention strategies for diabetes complications. PARTICIPANTS: At baseline, 337 271 patients with diabetes were identified. It includes 279 067 patients with type 2 diabetes, 17 638 with type 1 diabetes, 33 590 with gestational diabetes and 6916 with unspecified diabetes. The earliest diabetes diagnosis dates to January 1932, with data updated to 27 May 2025. FINDINGS TO DATE: This cohort profile describes baseline characteristics of patients with comprehensive data collected on demographics (age, sex, Deprivation Index, ethnicity), clinical measures (glycated haemoglobin, body mass index, blood pressure, lipids and estimated glomerular filtration rate) and 14 major diabetes complications tracked longitudinally. Key findings for patients with type 2 diabetes reveal diabetic retinopathy as the most common complication (74.6 per 1000 person-years), followed by hypertension (51.0) and kidney disease (31.4). Cumulative incidence analyses using the Aalen-Johansen estimator, which accounts for mortality as a competing risk, demonstrated significant ethnic disparities, with black, Asian, mixed and other ethnic groups showing elevated risk compared with white patients. Time-varying Cox models identified strong clustering between cardiovascular and renal complications, confirming a cardiometabolic-renal syndrome. Mental health conditions (depression and anxiety) were prevalent throughout the disease timeline, occurring both before and after diabetes diagnosis. FUTURE PLANS: This cohort will be used as a platform for developing and validating prognostic models for diabetes complications, enabling risk stratification and targeted interventions. Future work will incorporate medication data to refine diabetes type classification, examine the effectiveness of antidiabetic medications in preventing different complications and address demographic differences in prognostic model performance and prediction accuracy. To better characterise lifestyle, further interrogation of electronic health record data will examine recording of advice given, including dietary advice, referral to weight management schemes and presence of alcohol consumption codes.

Humans↗
PubMed2006

Magnification-corrected photodynamic therapy.

BACKGROUND: To present a method for performing photodynamic therapy (PDT) with a constant predictable light fluence based on actual laser spot magnification. METHODS: A calibrated Gullstrand-type model eye with a scale of half circles in the centre of the artificial fundus was used for this study. The axial length of the model eye was set to different values ranging from 20 to 31 mm, and the actual laser spot magnification of four indirect condensing laser lenses were determined using a PDT laser unit. RESULTS: Equations for determining the actual laser spot magnification were calculated for each laser lens. The total change in laser spot magnification from hyperopia (axial length 20 mm) to myopia (axial length 31 mm) was -20% to +24.8% for Mainster Standard lens (Ocular Instruments Inc, Bellevue, Washington, USA), -15.7% to +27.7% for Mainster Wide Field lens (Ocular Instruments Inc), -16.3% to +33.1% for Volk Transequator lens (Volk Optical Inc, Mentor, Ohio, USA), and -19.2% to +24.4% for Volk PDT Laser lens (Volk Optical Inc). CONCLUSIONS: Axial length of the eye has a considerable effect on PDT laser spot magnification when an indirect laser lens is used. By calculating the actual laser spot magnification in conjunction with knowledge of the true greatest linear dimension of the neovascular lesion, the clinician may be able to deliver a constant predictable amount of light fluence to the fundus independent of the axial length of the PDT treating eye.

Choroidal Neovascularization↗
PubMed2006

A comparison of pattern and multifocal electroretinography in the evaluation of age-related macular degeneration and its treatment with photodynamic therapy.

This study compares pattern electroretinography (PERG) and multifocal electroretinography (mfERG) measures in 13 patients with predominantly classic choroidal neovascularisation (CNV) associated with age-related macular degeneration (ARMD, 9/13 unilateral, 4/13 bilateral), assesses the usefulness of each test in monitoring disease progression, and identifies electrophysiological predictors of outcome following treatment with photodynamic therapy (PDT). PERG and mfERGs were recorded at presentation, 2 weeks post-treatment, and at 3 monthly intervals for 2 years. The PERG was detectable in 8/13 patients with unilateral disease; the mfERG was detectable in 12/13 patients. P50 and N95 amplitudes increased in 6/8 patients and mfERG p1 increased in 7/13 patients at 2 years. PERG amplitudes correlated strongly with mfERG amplitudes in patients with unilateral disease. PERG P50 and mfERG p1 amplitude correlated with visual acuity at 2 years (R = 0.68, R = 0.82, respectively). The largest PERG P50 and mfERG p1 amplitude difference between treated and fellow eyes of all the groups on initial visit was associated with a poor visual outcome (P50 64% difference; p1 29% difference) whereas those with the smallest P50 and p1 amplitude difference was associated with improved vision at 2 years (P50 30% difference; p1 21% difference). The PERG and mfERG provide an objective measure of central retinal function in the progression of ARMD. A detectable PERG on presentation was the single best indicator of improved function and visual acuity at 2 years. The mfERG demonstrated disease progression from central retina into the paramacular regions over 2 years. Patients with poor visual outcomes had the largest inter-ocular amplitude difference on presentation, suggesting that such patients may have a worse prognosis following treatment.

Disease Progression↗
PubMed2006

Hemorheologic abnormalities associated with HIV infection: in vivo assessment of retinal microvascular blood flow.

PURPOSE: To evaluate retinal microvascular blood flow in human immunodeficiency virus (HIV)-infected individuals using scanning laser Doppler flowmetry (SLDF) and to seek correlations between flow and various laboratory measures that may predict alterations in flow. METHODS: The Heidelberg Retina Flowmeter and SLDF software were used to acquire in vivo retinal blood flow data from 24 HIV-infected individuals and 16 HIV-negative control subjects. In each subject, separate scans were performed in each of six retinal regions: nasal parapapillary retina; macula; and the superior, nasal, inferior, and temporal periphery. Erythrocyte aggregation (assessed in vitro by a fully automatic erythrocyte aggregometer and by zeta sedimentation ratio [ZSR, a hematocrit-independent sedimentation rate]), serum fibrinogen level, plasma viscosity, and leukocyte rigidity (assessed in vitro with a cell transit analyzer) were compared with flow in selected regions. RESULTS: Flow was significantly higher in the periphery (superior, nasal, inferior, temporal) than in the posterior retina (nasal parapapillary retina, macula). Flow was highest in the temporal periphery for both HIV-infected subjects and control subjects. Flow in the posterior retina was significantly lower in HIV-infected subjects than in control subjects (P < 0.0001). Among HIV-infected individuals, flow in the macula correlated negatively with ZSR (r = -0.397, P = 0.0547) and leukocyte rigidity (r = -0.505, P = 0.0119). CONCLUSIONS: Microvascular blood flow in the posterior retina is reduced in HIV-infected individuals. Both increased erythrocyte aggregation and increased leukocyte rigidity contribute to this hemorheologic abnormality.

Adult↗
PubMed2004

Retinal and choroidal biopsies are helpful in unclear uveitis of suspected infectious or malignant origin.

OBJECTIVES: To assess the clinical value of retinal or choroidal biopsy in establishing a definitive diagnosis directing subsequent management and to assess the risk involved in such surgery. DESIGN: Retrospective noncomparative interventional case series. PARTICIPANTS: Thirteen patients with uveitis of suspected malignant or infectious origin. One patient had 2 consecutive biopsies on the same eye. METHODS: A retrospective review of a 4-year period was undertaken of all those cases in which the biopsy was taken for diagnostic purposes at a single institution. MAIN OUTCOME MEASURES: Ability of biopsy to establish a pathologic diagnosis and guide treatment and surgical complications. RESULTS: A transscleral approach was used in 4 and a pars plana vitrectomy approach in 10 of the biopsies. The only operative complication was a retinal break in 1 case. Postoperative events that might be related to the surgery included 1 localized retinal detachment, 2 cataracts, and 1 phthisical eye. The pathologic diagnosis differed from the initial clinical diagnosis in 5 of the 13 cases. The biopsy result directed specific appropriate treatment in 7 of the 13 cases. In the 6 remaining cases, no specific diagnosis was confirmed, but the results of the biopsy were useful in excluding malignancy and in some cases allowing a therapeutic trial. CONCLUSIONS: Retinal or choroidal biopsy is a valuable investigation that often changes clinical management when carried out for specific indications in patients with uveitis of suspected malignant or infectious origin. Although it is likely to remain an investigation of last resort, it should be considered at an earlier stage when there is diagnostic uncertainty if severe visual loss is to be prevented.

Adult↗
PubMed2004

Association of drusen deposition with choroidal intercapillary pillars in the aging human eye.

PURPOSE: To determine the pattern of drusen accumulation with age and to investigate the initial sites of deposition and their relationship to choroidal capillaries in human donor eyes from the eye bank of Moorfields Eye Hospital. METHODS: Wholemounted, hydrated preparations of the choriocapillaris and Bruch's membrane from donor eyes ranging from 42 to 95 years, with or without retinal pigment epithelium (RPE), were examined by conventional and confocal microscopy. Drusen were visualized by their autofluorescence. RESULTS: In all age groups studied autofluorescent drusen were present at the equator but were not found centrally where the vascular architecture is different, being tubular rather than a honeycomb pattern. Autofluorescing drusen were strongly associated with the lateral walls of the choriocapillaris (an area commonly known as the intercapillary pillars of the choriocapillaris (P = 0.028; Wilcoxon signed ranks test). Nonfluorescing drusen were occasionally seen centrally, but were not easily identified, and because of their large size, their localization with respect to capillary walls was not possible. CONCLUSIONS: These results strongly support the notion that autofluorescent drusen are not randomly distributed and have a specific spatial relationship to choroidal vessel walls. That equatorial drusen fluoresce, whereas central drusen do not, suggests that they may have different chemical compositions at the two sites and possibly different significance in age-related macular disease.

Adult↗
PubMed2003

Persistently culture positive acanthamoeba keratitis: in vivo resistance and in vitro sensitivity.

PURPOSE: To characterize the risk factors, clinical course, treatment outcome and the association between in vivo resistance and in vitro sensitivity for subjects with persistently culture-positive Acanthamoeba keratitis. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Eleven subjects with repeatedly positive cultures for Acanthamoeba treated between January 1990 and December 2000, were reviewed. Only subjects with 2 or more positive cultures, availability of the clinical data, and availability of the last Acanthamoeba isolate were included in this study. METHODS: The medical records were analyzed, and the last isolate from each case was tested in vitro for the antiamoebic drugs used clinically: polyhexamethylene biguanide (PHMB), chlorhexidine, propamidine and hexamidine. MAIN OUTCOME MEASURES: Risk factors, the clinical outcome and in vitro cysticidal drug sensitivity assay. RESULTS: Eleven subjects (11/180, 6.1%) had 2 or more positive cultures of whom 8 eyes of 8 subjects (8/180, 4.45%) were included in this study. Seven of eight (87%) subjects were diagnosed over 1 month from onset (late diagnosis). The most common presenting findings were diffuse stromal infiltrate (5/8, 62.5%), ring infiltrate (5/8, 62.5%), and corneal ulceration (3/8, 37.5%). The clinical course of the disease in all subjects consisted of recurrent episodes of corneal and scleral inflammation, with a mean duration of 13.4 +/- 9 months. All subjects received PHMB, and 5/8 (62.5%) chlorhexidine too; hexamidine was used in combination in 6/8 (75%), and propamidine in 1/8 (12.5%). All subjects had topical steroids, and 5/8 (62.5%) systemic immunosuppression. The disease resolved with corneal scarring in 3/8 (37.5%) subjects, corneal (or impending) perforation treated with therapeutic keratoplasty in 4/8 (50%), and enucleation in 1/8 (12.5%). Final visual acuity was 0.43 +/- 0.37. In vitro most isolates were resistant to propamidine, hexamidine was cysticidal in high concentrations, and PHMB and chlorhexidine had excellent sensitivity profiles. CONCLUSIONS: In our large series of Acanthamoeba keratitis with a positive microbiologic diagnosis at presentation, nearly 5% developed recurrent episodes of corneal and scleral inflammation with viable Acanthamoeba in the cornea despite prolonged treatment with biguanides and/or diamidines. There was no correlation between in vitro drug sensitivities and the in vivo response for biguanides.

Acanthamoeba↗