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Biomedical subjects

W M Amoaku

Publications and source records attributed to W M Amoaku.

At least 19 recordsLinked to original sources
PubMed2006

Syphilitic acute posterior placoid chorioretinitis in nonimmuno-compromised patients.

PURPOSE: To describe the clinical and angiographic features of three cases of secondary syphilis in immunocompetent patients, which presented as acute posterior placoid chorioretinitis (APPC) to the ophthalmologist. METHODS: Interventional case series. The aetiology of the APPC was confirmed by serology to be secondary syphilis. Optical coherence tomography, electrophysiology, fundus fluorescein, and indocyanine green (ICG) angiography were performed at presentation and after resolution. Appropriate treatment for secondary syphilis was instituted in each patient. RESULTS: The clinical features, fundus fluorescein and ICG angiography, multifocal electroretinography (mfERG), and optical coherence tomography findings of APPC are described. All three patients had a satisfactory resolution of the APPC with improvement in visual acuity. CONCLUSIONS: APPC in secondary syphilis can occur even in immunocompetent patients. A high index of suspicion is required for early diagnosis of this condition resulting in a good visual outcome with adequate treatment. mfERG and optical coherence tomography are useful in the diagnosis and follow-up of these patients.

Adult↗
PubMed2006

The management of retinal vein occlusion: is interventional ophthalmology the way forward?

Retinal vein occlusions (RVO) are the second commonest sight threatening vascular disorder. Despite its frequency treatments for RVO are unsatisfactory and include several that have not been tested by large, well designed, prospective, randomised controlled trials. There is also the lack of long term follow up in many of the available small uncontrolled studies, and the timings of interventions are haphazard. This review aims to evaluate the current knowledge relating to the pathogenesis, suggested treatments for the different types of RVO, and their complications. Isovolaemic haemodilution is of limited benefit and should be avoided in patients with concurrent cardiovascular, renal, or pulmonary morbidity. Evidence to date does not support any therapeutic benefit from radial optic neurotomy, optic nerve decompression, or arteriovenous crossing sheathotomy on its own. Vitrectomy combined with intravenous thrombolysis may offer promise for central RVO. Similarly, vitrectomy combined with arteriovenous sheathotomy intravenous tissue plasminogen activator may offer benefits for branch RVO. RVOs occur at significantly high frequency to allow future prospective randomised controlled studies to be conducted to evaluate the role of different therapeutic modalities singly or in combination.

Anticoagulants↗
PubMed2006

Effect of age related macular degeneration on the Eger macular stressometer photostress recovery time.

AIM: To assess the repeatability of Eger macular stressometer (EMS) measures of photostress recovery and determine their association with other measures of visual function. METHODS: EMS photostress recovery time was measured in 90 patients with bilateral exudative age related macular degeneration (AMD), 19 with bilateral atrophic AMD and 47 with both forms of the condition (mean age 79 (SD 13) years). Measurements were made on two occasions separated by 1 year. Intrasession repeatability was assessed by repeating the measures after a 10 minute recovery period at the first visit. Distance visual acuity was measured with a logMAR chart, near visual acuity with a MNRead chart at 25 cm, contrast sensitivity with a Pelli-Robson chart, and the presence of central visual disturbance assessed with an Amsler grid. A questionnaire was used to assess self reported difficulties with glare recovery. RESULTS: The average EMS recovery time was 11.0 (SD 8.9) seconds, decreasing by 1.6 (5.2) seconds on repeated measurement (p<0.05). EMS photostress recovery was not correlated with visual function measures or subjective difficulties with lights (p>0.05). EMS photostress recovery time did not predict those whose vision decreased over the following year compared with those among whom it remained stable. CONCLUSIONS: The EMS test is not a useful tool in determining the severity or progression of AMD.

Adaptation, Ocular↗
PubMed2005

Verteporfin photodynamic therapy of choroidal neovascularization in angioid streaks: one-year results of a prospective case series.

PURPOSE: To report the 12-month results on the use of verteporfin photodynamic therapy (PDT) in the treatment of choroidal neovascularization (CNV) secondary to angioid streaks. STUDY DESIGN: Five-center prospective case series. METHODS: Patients with CNV secondary to angioid streaks who were treated with PDT were recruited and followed up at 3-month intervals for 12 months, with the addition of visits at 1.5 and 4.5 months if deemed appropriate by the investigator. Best-corrected visual acuity (BCVA) was measured at each visit after full refraction or with their current distance spectacles using Early Treatment Diabetic Retinopathy Study logarithm of the minimum angle of resolution charts. Stereoscopic fundus fluorescein angiography was used to determine baseline lesion characteristics and location. RESULTS: Twenty-two patients were recruited (23 eyes, 16 with subfoveal CNV and 7 with juxtafoveal; all classic no occult). Seventeen patients (77%) had angioid streaks secondary to pseudoxanthoma elasticum. In the subfoveal group, median BCVA at baseline was 49 letters (approximate Snellen equivalent, 20/100) and was 46 at 12 months (approximate Snellen equivalent, 20/125). Twelve of 16 eyes (75%) lost fewer than 8 letters, whereas 14 of 16 eyes (88%) lost fewer than 15 letters. The mean CNV greatest linear dimension (GLD) was 2520 microm at baseline. At 12 months, 7 of 16 eyes with subfoveal CNV at baseline were leaking (GLD = 3220 microm; P = 0.62). The mean number of treatments in the first 12 months was 2.9. In the juxtafoveal group, the median BCVA at baseline was 66 letters (approximate Snellen equivalent, 20/50) and was 51 letters at 12 months (approximate Snellen equivalent, 20/100). Two of 7 eyes (29%) gained 8 or more letters at the 12-month examination, whereas 4 of 7 eyes (57%) lost more than 15 letters. The mean CNV GLD at baseline was 1890 microm. At 12 months, 1 of 7 eyes with juxtafoveal CNV at baseline was leaking. Choroidal neovascularization progressed from juxtafoveal to subfoveal location during the follow-up period in 4 of 7 eyes. The mean number of treatments in the first 12 months was 3.4. No side effects were noted in either patient group. CONCLUSIONS: This small series suggests that treatment of CNV secondary to angioid streaks with verteporfin PDT seems to limit visual loss in most patients through the first 12 months of follow-up, particularly in those with subfoveal lesions at baseline.

Adult↗
PubMed2005

The efficacy of sirolimus in the treatment of patients with refractory uveitis.

AIMS: To determine the efficacy of sirolimus in the treatment of patients with severe non-infectious uveitis. METHODS: Eight patients with severe non-infectious uveitis were recruited to an open study. Inclusion criteria were limited to patients whose disease was not controlled with at least two or more separate steroid sparing immunosuppressants (either because of unacceptable side effects or ineffectiveness of the drug) or who required regular doses of corticosteroids either as high dose systemic or orbital floor injections in order to control their disease. Intraocular inflammation, visual acuity, symptoms, corticosteroid burden, drug toxicity, and side effects were monitored. RESULTS: Sirolimus therapy was effective in five of the eight patients, all of whom had their dose of corticosteroids reduced or discontinued. Treatment in three patients was considered a failure as it caused intolerable side effects and/or failed to control the uveitis. Side effects were common and were typically gastrointestinal or cutaneous in nature. The severity of symptoms was dose dependent in most cases and occurred at trough blood levels above 25 ng/ml. CONCLUSION: Sirolimus is an effective and potent immunosuppressive treatment in the majority of patients with non-infectious uveitis and can reduce the need for long term supplementary corticosteroid therapy. Further studies are required to establish the long term efficacy and safety of sirolimus alone or in combination with other steroid sparing immunosuppressants.

Adult↗
PubMed2005

Isolation, culture, and characterisation of human macular inner choroidal microvascular endothelial cells.

AIM: To develop a method for the reliable isolation of adult human macular inner choroidal endothelial cells (ICECs) and to subsequently characterise them for their expression of a range of endothelial cell associated surface markers. METHOD: Human ICECs were isolated after manual dissection of maculas from fresh human posterior segments. Following enzyme digestion to form a single cell suspension, the ICECs were isolated using anti-CD31 coated Dynabeads. The isolated cells were grown in culture and examined for typical endothelial cell morphology, surface expression of vWf, CD 31, CD 105, VEGF receptors 1 and 2, and expression of E-selectin after stimulation with TNF-alpha. The cells were also examined for their ability to form fenestrations and capillary-like tubes in Matrigel. RESULTS: The method enabled the rapid isolation of viable cells that demonstrated typical endothelial cobblestone morphology in culture. The cells stained positive for CD31, vWf, CD105, VEGF receptors 1 and 2, and E-selectin (after stimulation with TNF-alpha). The cells stained negative for alpha smooth muscle actin and fibroblast surface protein. The cells also developed fenestrations when cultured on fibronectin coated plates and formed capillary-like tubes structures when cultured on Matrigel. CONCLUSIONS: This technique isolates cells from the human macular inner choroid that display features consistent with vascular endothelial cells. These cells could subsequently be used to further the understanding of the pathophysiological mechanisms of diseases of the inner choroid, such as choroidal neovascularisation.

Adult↗
PubMed2001

Visual outcome of malignant hypertension in young people.

A retrospective review was carried out of patients under 16 years old with malignant hypertension, who had been referred to a teaching hospital ophthalmology department because of reduced visual acuity. Four patients (three girls, one boy) were seen between 1994 and 2000 with a mean age at presentation of 11.5 years (range 9-15). In the short term, visual acuity improved after control of blood pressure in all four patients. However, in the long term, two patients were registered blind one to two years after presentation, one because of a choroidal neovascular membrane developing at the macula, and the other because of progressive optic neuropathy. Both of these patients had a longer duration of symptoms before diagnosis, worse visual acuity, and higher blood pressure at presentation when compared with the patients who made a good visual recovery. These observations suggest that early diagnosis of malignant hypertension in children is essential in reducing the likelihood of permanent severe visual damage.

Adolescent↗
PubMed1999

Reproducibility of volumetric macular measurements in diabetic patients with the Heidelberg Retina Tomograph.

AIMS: To quantify diabetic macular edema by confocal scanning laser ophthalmoscopy and assess its usefulness by determining the reproducibility of topographic measurements at the macula. METHODS: The volumes above reference plane bound by a 2 mm diameter circle centred on the fovea were measured by two observers. The reference plane was adjusted to the lowest point of the height variation of the contour line. The reproducibility of this technique was assessed in 20 eyes of 20 diabetic patients of which 8 eyes had macular edema. Three HRT scans of each eye were obtained. The measurements of volume above reference plane of each scan were repeated three times. RESULTS: For all diabetic eyes, the intra scan coefficients of variability measured 14.71% to 21.21%, the inter scan coefficient of variability was 30.46%. The average standard deviations were 0.053 mm3 for one examination per scan, 0.047 mm3 for two examinations per scan and 0.044 mm3 for three examinations per scan. Linear regression demonstrated an increase in standard deviation with greater volumetric measurements (p < 0.001). We found good correlation (r = 0.959, p < 0.001) and strong agreement between the two observer's findings for all 20 eyes. For the 8 eyes with macular edema, the coefficients of variability were similar to those calculated for all 20 eyes. The average SD for one examination per scan were 0.078 mm3, 0.069 mm3 for two examinations per scan and 0.062 mm3 for three examinations per scan. We found good correlation (r = 0.945, p < 0.001) and strong agreement between the two observer's findings in eyes with edema. CONCLUSION: The reproducibility of this technique has been demonstrated in diabetic eyes. This may have useful clinical applications for the quantification of diabetic macular edema and monitoring of laser therapy.

Adult↗
PubMed1998

Volumetric analysis of early macular edema with the Heidelberg Retina Tomograph in diabetic retinopathy.

OBJECTIVE: This study describes a new method for the quantification of diabetic macular edema by volumetric analysis with the Heidelberg Retina Tomograph (HRT) scanning laser ophthalmoscope. DESIGN: Topographic images of the macula were obtained in 25 consecutive patients who fitted the inclusion criteria. Twenty age-matched control subjects were randomly selected for a similar examination. PARTICIPANTS: Twenty normal control eyes and 32 eyes of 25 patients with diabetes mellitus were studied. INTERVENTION: Patients with diabetes were examined by HRT and slit-lamp biomicroscopy with a contact lens. On HRT, the volumes above reference plane bound by three consecutive circles centered at the fovea (diameter, 1, 2, and 3 mm) were measured. Measurements were repeated three times in a masked fashion, and the mean measurements were used for the analysis. MAIN OUTCOME MEASURES: Visual acuity, macular edema, and volume above reference plane were measured. RESULTS: There were 19 diabetic eyes with clinical macular edema (deemed positives) and 13 without edema (deemed negatives). Diabetic eyes with macular edema had statistically greater volumes above reference plane than did diabetic eyes without edema (P < 0.001) and greater than the control eyes (P < 0.001) for all three circles. There was no statistically significant difference between volumes measured in eyes without macular edema and control eyes (P = 0.42 for the 1-mm diameter circle; P = 0.72 for the 2-mm diameter circle; and P = 0.19 for the 3-mm diameter circle). For the two smallest circles only, the sensitivity of the HRT was 78.94%, and the specificity was 84.61%. None of the patients missed on the two smallest circles would have been positively identified on the 3-mm diameter circle. CONCLUSION: The HRT can detect and quantify macular edema in diabetes by volumetric analysis with the method the authors have described. It is sufficient to measure the volumes above reference plane of two circles centered on the fovea and measuring 1 and 2 mm in diameter because the 3-mm diameter circle does not increase the system's sensitivity.

Aged↗
PubMed1998

Reproducibility of volumetric measurements of normal maculae with the Heidelberg retina tomograph.

AIMS: The Heidelberg retina tomograph (HRT) is a scanning laser ophthalmoscope with confocal optics. The reproducibility of the optic nerve head topography is accurate and reliable. The authors describe a new technique for the assessment of macular thickening by volumetric quantification and present the results of its reproducibility in normal subjects. METHODS: Topographic images of the macula, centred on the fovea were obtained in one eye of 44 normal subjects. The volumes above the reference plane bound by a 1 mm, 2 mm, and 3 mm diameter circle were measured. The reference plane was adjusted to the lowest point of the height variation of the contour line at each examination. The reproducibility of repeated measurements within a 2 mm diameter circle was assessed in 20 eyes selected at random. Three HRT scans of each eye were obtained. The measurements of volume above reference plane of each scan were repeated three times on three separate days. RESULTS: The intrascan coefficients of variability measured 7.12-9.57%. The 95% confidence interval for the geometric mean ratio of single volume measurements was 0.92 to 1.24 for scans 1 and 2, 0.89 to 1.17 for scans 1 and 3, and 0.81 to 1.12 for scans 2 and 3. When the mean of three measurements of one scan were compared with the mean of three measurements of a second scan, the 95% confidence interval for their geometric mean ratio was 0.89 to 1.20 for scans 1 and 2, 0.89 to 1.16 for scans 1 and 3, and 0.84 to 1.13 for scans 2 and 3. The average standard deviation (SD) for one measurement per scan was 0.02 mm3, and 0.019 mm3 for two or three measurements per scan. Linear regression demonstrated a significant increase in SD as volumetric measurements increased (p = 0.003). Age did not significantly affect the SD of volumetric measurements (p = 0.797). The authors found no significant differences in volumetric measurements across all ages for all three circles (p = 0.314, p = 0.471, p = 0.267). CONCLUSION: Good reproducibility for volumetric measurements at the macula was found with the HRT using the above technique in normal subjects. This method may be extremely useful for the identification and quantification of diabetic macular oedema and for monitoring the effects of argon laser photocoagulation.

Adult↗
PubMed1996

Trilateral retinoblastoma. A report of five patients.

BACKGROUND: Trilateral retinoblastoma is a well recognized, although rare, syndrome. Most of the reported cases have involved a family history of retinoblastoma (RB) and the disease is almost always fatal. The authors chose to investigate the cases of trilateral retinoblastoma occurring in the West Midlands, a region of the United Kingdom with an increasing incidence of bilateral sporadic RB. METHODS: Five patients with trilateral retinoblastoma (including two were previously reported), diagnosed in 146 consecutive patients with RB in the West Midlands Health Authority Region between 1957 and 1994, are presented (an incidence of 3%). Their clinical presentation, treatment, and outcome are described. RESULTS: There were 4 patients with pineoblastoma, only one of whom had a positive family history. The mean age at diagnosis of RB and 6 months, whereas the patients with pineoblastoma were diagnosed at a mean age of 2 years 8 months. The tumors were not evident on the initial computed tomography scans. One child presented with a calcified suprasellar mass 13 months before the bilateral sporadic RB was identified. Death occurred within 1 month of diagnosis of the intracranial tumor in 3 patients who did not receive any treatment. In the other 2 patients who were treated, death occurred at 15 months and 2 years 7 months, respectively, after diagnosis of intracranial tumor. CONCLUSIONS: Early diagnosis with regular neuro-imaging and more aggressive treatment may improve prognosis in patients with RB and an intracranial tumor.

Child↗
PubMed1995

Indocyanine green angiography of choroidal tumors.

BACKGROUND: Fluorescein angiography (FA) has been widely used in the diagnostic evaluation of choroidal tumors. Indocyanine green angiography (ICG-A), which permits better visualization of choroidal vasculature than FA, has been recently introduced into clinical practice. Only few reports exist on the ICG-A characteristics of choroidal tumors. METHODS: The fluorescein and indocyanine green angiograms of 61 patients were assessed. These included 14 patients with choroidal nevi, 30 with malignant melanomas, 7 with suspected melanomas or atypical nevi, 5 with hemangiomas and 5 with metastases. RESULTS: The outline of pigmented tumors was more accurate on ICG-A than on FA. Characteristic patterns were seen in all intra-ocular tumors with ICG-A, so it was possible to distinguish hemangiomas from malignant lesions. Characteristic features of malignant melanomas include abnormal vascular pattern and marginal late dye leakage. None of the benign lesions showed these features. In suspected melanomas, the presence of abnormal choroidal vascular patterns and/or late dye leakage on ICG-A may indicate malignancy. CONCLUSION: The study suggests that ICG-A can yield additional information that is useful in differentiating amongst choroidal tumors. Better delineation of pigmented lesions with ICG-A allows more accurate treatment planning and follow-up.

Choroid Neoplasms↗
PubMed1995

Radiation choroidal vasculopathy: an indocyanine green angiography study.

An indocyanine green angiography (ICG-A) study of choroidal vasculature in the irradiated peritumoral zone in 16 eyes treated with 106Ru/106Rh brachytherapy for choroidal melanoma was performed between 4 and 72 months following treatment. The earliest changes observed were peritumoral atrophy of the retinal pigment epithelium and choriocapillaries. With time, the larger choroidal vessels progressively became non-perfused. There was only minimal staining of the smaller vessels. However, at 2 years or more after radiotherapy the larger choroidal vessels showed progressive vascular wall staining with ICG ('perivasculitis') associated with continuing closure. Previous histopathological studies of radiation damage to the choroid have demonstrated atrophy and occlusion of the vasculature but have shown no evidence of vasculitis. It is suggested that ICG staining of the choroidal vascular wall in radiation choroidopathy is due to radiation-induced endothelial cell loss or dysfunction rather than a true vasculitis. Subsequent progression results in vascular occlusion, and development of new clusters of abnormal choroidal vessels.

Angiography↗
PubMed1994

Thirty years of retinoblastoma (1960-89): changing patterns of incidence.

This study of a 30-year population-based dataset investigates further an earlier observation that the incidence of sporadic bilateral retinoblastoma appeared to be increasing in recent years in the West Midlands Health Authority Region (WMHAR). Stringent measures were applied to ensure complete ascertainment of all cases of retinoblastoma in children in the region, resulting in a total of 117 cases diagnosed during the period 1960-89 in the WMHAR. Hospital case notes were abstracted and follow-up data obtained. Incidence rates were calculated. The overall incidence remained constant over the 30-year period, but that of sporadic bilateral tumours increased, with a corresponding decline in familial cases. There was a statistically significant excess seen in Asian children.

Age Distribution↗