Showing papers by "Adnan Tufail published in 2016"

Assessment of red blood cell deformability in type 2 diabetes mellitus and diabetic retinopathy by dual optical tweezers stretching technique

Abstract: A pilot cross sectional study was conducted to investigate the role of red blood cells (RBC) deformability in type 2 diabetes mellitus (T2DM) without and with diabetic retinopathy (DR) using a dual optical tweezers stretching technique. A dual optical tweezers was made by splitting and recombining a single Nd:YAG laser beam. RBCs were trapped directly (i.e., without microbead handles) in the dual optical tweezers where they were observed to adopt a "side-on" orientation. RBC initial and final lengths after stretching were measured by digital video microscopy, and a Deformability index (DI) calculated. Blood from 8 healthy controls, 5 T2DM and 7 DR patients with respective mean age of 52.4 yrs, 51.6 yrs and 52 yrs was analysed. Initial average length of RBCs for control group was 8.45 ± 0.25 μm, 8.68 ± 0.49 μm for DM RBCs and 8.82 ± 0.32 μm for DR RBCs (p < 0.001). The DI for control group was 0.0698 ± 0.0224, and that for DM RBCs was 0.0645 ± 0.03 and 0.0635 ± 0.028 (p < 0.001) for DR group. DI was inversely related to basal length of RBCs (p = .02). DI of RBC from DM and DR patients was significantly lower in comparison with normal healthy controls. A dual optical tweezers method can hence be reliably used to assess RBC deformability.

The Evaluation of Diabetic Macular Ischemia Using Optical Coherence Tomography Angiography

Abstract: Purpose The purpose of this study was to compare optical coherence tomography (OCT) angiography to standard fluorescein angiography (FA) in the grading of diabetic macular ischemia. Methods In our study, OCT angiography and traditional FA images were acquired from 24 diabetic patients. The level of diabetic macular ischemia in the superficial capillary plexus was graded with standard Early Treatment Diabetic Retinopathy Study (ETDRS) protocols and a comparison between conventional FA and OCT angiography was performed. The deep vascular plexus and choriocapillaris were also graded for macular ischemia. Additionally, flow indices were analyzed for all OCT angiography images. Results We identified moderate agreement between diabetic macular ischemia grades for conventional FA and OCT angiography (weighted κ of 0.53 and 0.41). In addition, the intergrader agreement for the superficial, deep, and choriocapillaris scores was substantial (weighted κ of 0.65, 0.61, and 0.65, respectively). Finally, the parafoveal flow indices were shown to have a statistically significant relationship with diabetic macular ischemia grades for the superficial capillary plexus (P = 0.04) and choriocapillaris (P = 0.036), with a trend toward significance for the deep capillary plexus (P = 0.13). Conclusions We demonstrated moderate agreement between diabetic macular ischemia grading results for OCT angiography and conventional FA using standard ETDRS protocols. We also showed that OCT angiography images could be graded for diabetic macular ischemia with substantial intergrader agreement.

Optical coherence tomography angiography and indocyanine green angiography for corneal vascularisation

Abstract: Background/Aim To describe an optical coherence tomography angiography (OCTA) system adapted for anterior segment imaging, compared with indocyanine green angiography (ICGA) in eyes with corneal vascularisation. Methods Retrospective study of subjects with corneal vascularisation secondary to microbial keratitis who had OCTA scans performed using a commercially available split-spectrum amplitude-decorrelation algorithm angiography system (AngioVue; Optovue Inc., Fremont, California, USA) and ICGA images (Spectralis; Heidelberg Engineering, Heidelberg, Germany). The agreement between OCTA and ICGA techniques in terms of area of vascularisation measured, using Bland–Altman 95% limits of agreement (LOA). Results We compared the area of corneal vascularisation in 64 scan images (eight eyes, four scans for each angiography technique). In our series, the overall mean area of vascularisation from the ICGA scans was 0.49±0.34 mm 2 and OCTA scans was 0.51±0.36 mm 2 . We obtained substantial repeatability in terms of image quality score (κ=0.80) for all OCTA scans. The agreement between OCTA and ICGA scans was good, although ICGA measured a smaller area compared with the OCTA with a mean difference of −0.03 mm 2 (95% CI −0.07 to 0.01). The LOA ranged from a lower limit of −0.27 (95% CI −0.34 to −0.19) to an upper limit of 0.20 (95% CI 0.13 to 0.28, p=0.127). Conclusions We found that rapid, non-contact OCTA adapted for the cornea was comparable with ICGA for measurement of the area of corneal vascularisation in this pilot clinical study. Further prospective studies are required to confirm if this relatively new imaging technique may be further developed to replace invasive angiography techniques for the anterior segment.

En face optical coherence tomography angiography for corneal neovascularisation

Abstract: Background/aim Recently, there has been an increasing clinical need for objective evaluation of corneal neovascularisation, a condition which cause significant ocular morbidity. We describe the use of a rapid, non-invasive ‘en face’ optical coherence tomography angiography (OCTA) system for the assessment of corneal neovascularisation. Methods Consecutive patients with abnormal corneal neovascularisation were scanned using a commercially available AngioVue OCTA system (Optovue, Fremont, California, USA) with the split-spectrum amplitude decorrelation angiography algorithm, using an anterior segment lens adapter. Each subject had four scans in each eye by a trained operator and two independent masked assessors analysed all images. Main outcome measures were scan quality (signal strength, image quality), area of neovascularisation and repeatability of corneal vascular grade. Results We performed OCTA in 20 patients (11 men, 9 women, mean age 49.27±17.23 years) with abnormal corneal neovascularisation. The mean area of corneal neovascularisation was 0.57±0.30 mm 2 with a mean neovascularisation grade of 3.5±0.2 in the OCTA scans. We found the OCTA to produce good quality images of the corneal vessels (signal strength: 36.95±13.97; image quality score 2.72±1.07) with good repeatability for assessing neovascularisation grade (κ=0.84). Conclusions In this preliminary clinical study, we describe a method for acquiring angiography images with ‘en face’ views, using an OCTA system adapted for the evaluation of corneal neovascularisation. Further studies are required to compare the scans to other invasive angiography techniques for the quantitative evaluation of abnormal corneal vessels.

The Evolution of Teleophthalmology Programs in the United Kingdom: Beyond Diabetic Retinopathy Screening

Abstract: Modern ophthalmic practice in the United Kingdom is faced by the challenges of an aging population, increasing prevalence of systemic pathologies with ophthalmic manifestations, and emergent treatments that are revolutionary but dependent on timely monitoring and diagnosis. This represents a huge strain not only on diagnostic services but also outpatient management and surveillance capacity. There is an urgent need for newer means of managing this surge in demand and the socioeconomic burden it places on the health care system. Concurrently, there have been exponential increases in computing power, expansions in the strength and ubiquity of communications technologies, and developments in imaging capabilities. Advances in imaging have been not only in terms of resolution, but also in terms of anatomical coverage, allowing new inferences to be made. In spite of this, image analysis techniques are still currently superseded by expert ophthalmologist interpretation. Teleophthalmology is therefore currently perfectly placed to face this urgent and immediate challenge of provision of optimal and expert care to remote and multiple patients over widespread geographical areas. This article reviews teleophthalmology programs currently deployed in the United Kingdom, focusing on diabetic eye care but also discussing glaucoma, emergency eye care, and other retinal diseases. We examined current programs and levels of evidence for their utility, and explored the relationships between screening, teleophthalmology, disease detection, and monitoring before discussing aspects of health economics pertinent to diabetic eye care. The use of teleophthalmology presents an immense opportunity to manage the steadily increasing demand for eye care, but challenges remain in the delivery of practical, viable, and clinically proven solutions.

Evaluation of Nonperfused Retinal Vessels in Ischemic Retinopathy

Abstract: Purpose: Retinal ischemia has been traditionally assessed by fluorescein angiography, visualizing perfused vessels. However, this method does not provide any information about nonperfused vessels, and although it is often assumed that vessels in ischemic areas regress, we know little about how nonperfused retinal vessels change over time. Here, we aim to learn more about the long-term fate of nonperfused vessels in the retinal vasculature. Methods: Optical coherence tomography (OCT) was used to visualize perfusion as well as structural properties of the retinal vasculature in patients suffering from retinal vascular occlusions. In addition, postmortem tissue from a patient with long standing (6 years) central retinal vein occlusion (CRVO) was investigated, using immunohistochemistry on whole-mount retina and paraffin sections to visualize blood vessel components. Results: Comparing OCT angiography with enface OCT images revealed that in ischemic areas of the retina, nonperfused, larger vessels could be detected as hyperreflective structures in enface OCT images. Furthermore, analysis of a postmortem tissue sample from a CRVO patient with a large nonperfused region in the macula, revealed preservation of the basement membrane from all retinal vessels, including nonperfused, acellular vessels of all calibers. Conclusions: Our data suggests long-term preservation of vascular basement membrane in ischemic retina. This has implications for therapeutic approaches aiming to alleviate retinal ischemia via the regeneration of damaged vessels.

Visual acuity loss in patients with age-related macular degeneration measured using a novel high-pass letter chart

Abstract: Background/aims Conventional Logarithm of the Minimum Angle of Resolution (logMAR) acuity is the current gold standard for assessing visual function in age-related macular degeneration (AMD). However, visual acuity (VA) often remains ‘normal’ when measured with these charts, even with advanced retinal changes. We wished to investigate how VA measurements with the Moorfields Acuity Chart (MAC), which employs high-pass filtered letters, compares to conventional letter charts in subjects with AMD. Methods Monocular best-corrected VA measurements and test–retest variability (TRV) were compared for conventional and MAC charts in 38 normal observers (mean age 52.1 years) and 80 patients (mean age 80.6 years) with varying degrees of acuity loss owing to AMD. Methods of Bland–Altman and ordinary least-squares regression were employed for data analysis. Results A proportional bias was confirmed between conventional and MAC measurements (r 2 =0.133, p=0.001) such that MAC acuity was −0.45 logMAR ‘worse’ at the 0.00 logMAR acuity level, but only −0.26 logMAR ‘worse’ at the 1.00 logMAR level. The mean bias was much smaller in the normal subject group (−0.16 logMAR). Similar TRV (ranging from ±0.09 to ±0.12 logMAR) was found for both charts in both subject groups. Conclusions VA measurements with the MAC chart appear to be more sensitive to functional loss in AMD compared with conventional letter charts, with similar TRV. Simulations indicate this may be because the high-pass filtered letters are more vulnerable to undersampling as a result of retinal cell loss in the disease process.

Optical Coherence Tomography Features Of Active And Inactive Retinal Neovascularization In Proliferative Diabetic Retinopathy

Abstract: Purpose To describe spectral domain-optical coherence tomography features of retinal neovascularization in proliferative diabetic retinopathy and thus to identify novel signs of new vessel activity. Methods Retrospective, cross-sectional study. Data were collected over a 9-month period. Spectral domain optical coherence tomography scans were performed over areas of new vessel complexes (NVC) in both the disk and elsewhere, and were qualitatively graded by two masked observers. New vessel complexes activity was determined using clinical and angiographic criteria and correlated with spectral domain optical coherence tomography features. Results Forty-three eyes of 30 patients with proliferative diabetic retinopathy were included. Sixty-one NVC lesions (neovascularization of the disk-37.7%, neovascularization elsewhere-62.3%) were captured by spectral domain-optical coherence tomography and analyzed. Among them, 63.9% were classified as active and 36.1% as quiescent. Five distinctive features were identified as significantly different between active and quiescent NVC: the presence of vitreous hyperreflective dots in active NVC (P = 0.002) and the presence of epiretinal membrane (P = 0.04), inner retinal tissue contracture (P = 0.03), vitreous invasion (P = 0.02), and protrusion towards vitreous (P = 0.002) in quiescent NVC. Conclusion In this exploratory study, the presence of vitreous hyperreflective dots, epiretinal membrane, inner retinal tissue contracture, vitreous invasion, and vitreous protrusion were identified as distinct signs of disease activity. Such parameters may be useful as a noninvasive imaging modality in eyes undergoing treatment for proliferative diabetic retinopathy.

Ranibizumab in Myopic Choroidal Neovascularization: A Subgroup Analysis by Ethnicity, Age, and Ocular Characteristics in RADIANCE

Abstract: Purpose: To assess the impact of ethnicity, age, and ocular characteristics on ranibizumab efficacy in myopic choroidal neovascularization (CNV). Methods: In this post hoc subgroup analysis from the phase III RADIANCE study, best-corrected visual acuity (BCVA) outcomes and treatment exposure were analyzed in 105 patients treated with ranibizumab 0.5 mg. Baseline categories included ethnicity, age, baseline BCVA, lesion area, CNV lesion area, refraction sphere, axial length, subretinal fluid, and location of CNV. Results: At month 12, the mean change in BCVA was numerically higher in East-Asians than in Caucasians (17.0 vs. 14.1 letters). The median number of injections varied with ethnicity (East-Asians vs. Caucasians: 2 vs. 3), baseline BCVA (highest vs. lowest: 1 vs. 4), CNV lesion area and lesion area (largest vs. smallest: 5 vs. 1 and 5 vs. 2). Conclusions: East-Asians showed numerically higher BCVA gains than Caucasians. The number of injections varied across subgroups, emphasizing the need for individualized treatment.

UK Neovascular Age-Related Macular Degeneration Database. Report 6: time to retreatment after a pause in therapy. Outcomes from 92 976 intravitreal ranibizumab injections

Abstract: Background/aims To study the time to retreatment in eyes with neovascular age-related macular degeneration (nAMD) that had been treatment-free for intervals of 3 months, 6 months, 9 months and 12 months during the maintenance phase of ranibizumab therapy within the UK National Health Service. Methods In this multicentre national nAMD database study, structured data were collected from 14 centres (involving 12 951 eyes receiving 92 976 ranibizumab injections). Patients were treated with three fixed, monthly injections in a loading phase of treatment, followed by a pro re nata retreatment regimen in a maintenance phase. Eyes with a treatment-free interval (TFI) of 3 months, 6 months, 9 months or 12 months in the maintenance phase were identified and the time to retreatment after these TFIs was determined. Results The time to retreatment for the 20th and 50th centiles was 0.58/2.54 months after a 3-month TFI, 2.07/9.62 months after a 6-month TFI, 3.69/15.84 months after a 9-month TFI and 5.90/22.49 months after a 12-month TFI. Following a TFI of 3 months, 6 months, 9 months and 12 months, 68%, 44%, 31% and 21% of eyes required retreatments after an additional 6 months of follow-up, respectively. Similarly, after 12 months of follow-up, 77%, 56%, 43% and 34% of these eyes required retreatment. Conclusions This study provides times to retreatment in eyes with nAMD that have been treatment-free for intervals of 3–12 months and demonstrates the likelihood of repeat therapy within the next year, even after a TFI of 12 months. These outcomes can help plan appropriate follow-up intervals for patients who have been treatment-free for intervals of up to 12 months.

The UK Neovascular AMD Database Report 3: inter-centre variation in visual acuity outcomes and establishing real-world measures of care

Abstract: PurposeInternational variations in visual acuity (VA) outcomes of eyes treated for neovascular age-related macular degeneration (nAMD) are well-documented, but intra-country inter-centre regional variations are not known. These data are important for national quality outcome indicators. We aimed to determine intra-country and inter-centre regional variations in outcomes for treatment of nAMD.Patients and methodsProspective multicentre national database study of 13 UK centres that treated patients according to a set protocol (three loading doses, followed by Pro-Re-Nata retreatment). A total of 5811 treatment naive eyes of 5205 patients received a total of 36 206 ranibizumab injections over 12 months.ResultsMean starting VA between centres varied from 48.9 to 59.9 ETDRS letters. Mean inter-centre VA change from baseline to 12 months varied from +6.9 letters to -0.6 letters (mean of +2.5 letters). The proportion of eyes achieving VA of 70 letters or more varied between 21.9 and 48.7% at 12 months. Median number of injections (visits) at each centre varied from 5 to 8 (9 to 12), with an overall median of 6 (11). Age, starting VA, number of injections, and visits, but not gender were significantly associated with variation in these VA outcomes (P<0.01). Significant variation between centres persisted even after adjusting for these factors.ConclusionThere are modest differences in VA outcomes between centres in the UK. These differences are influenced, but not completely explained, by factors such as patient age, starting VA, number of injections, and visits. These data provide an indication of the VA outcomes that are achievable in real-world settings.

Vascular endothelial growth factor inhibitor use and treatment approach for choroidal neovascularization secondary to pathologic myopia

Abstract: Introduction: Myopic choroidal neovascularization (CNV) is the most common cause of CNV in those under 50 years of age. It is a significant cause of visual loss in those with pathologic myopia. The...

Multimodal retinal imaging in the diagnosis of intraretinal microvascular abnormality

Abstract: Introduction: Retinal imaging in diabetic retinopathy has experienced significant advances since the days of the Early Treatment for Diabetic Retinopathy Studies. Differentiating intraretinal microvascular abnormalities (IRMA) from neovascular complexes remain a challenging part of disease staging but may become easier in this age of multimodal imaging.Areas covered: This review presents an overview of the available imaging modalities, their current applications and limitations as well as future developments in the pipeline. The implication of new imaging technology on the traditional definition of IRMAs and how this may translate into potential treatment outcomes for the patient will be discussed. This review is based on a literature search of all English language articles published on PubMed.Expert commentary: The characterisation of IRMA has evolved with the development of OCT to identify morphological differences. Wide field imaging may also identify IRMA outside of standard field of view of c...