Search PubMed⌕ Search

Biomedical subjects

R S Newsom

Publications and source records attributed to R S Newsom.

16 recordsLinked to original sources
PubMed2006

Ocular morbidity associated with intravitreal triamcinolone acetonide.

AIM: To report on the complications associated with the use of intravitreal triamcinolone acetonide (IVTA) in a tertiary referral hospital setting. MATERIALS AND METHODS: A retrospective case series review of all IVTA injections carried out over a period of 30 months. RESULTS: One hundred and thirty IVTA injections were performed; nine with limited local follow-up were excluded. Thus, 121 injections (108 patients, 114 eyes) were included in the study. Triamcinolone (4 mg) was used in all cases. Indications were diabetic macular oedema (n=41 eyes), retinal vein occlusions (n=27), postoperative cystoid macular oedema (n=24), exudative age-related macular degeneration (n=16), and others (n=6). No intraoperative complications were recorded. Postoperative intraocular pressure (IOP) readings of 22, 28, 35, and 40 mmHg or higher were recorded in 46.5, 29.8, 12.3, and 7.9% of eyes, respectively. IOP elevation was treated with antiglaucoma medication in all but one eye (0.9%) that required trabeculectomy and one (0.9%) that required vitrectomy with cataract extraction for suspected phacoanaphylactic glaucoma. Two eyes (1.8%) developed retinal detachment; both had previously been treated for retinal breaks. One eye (0.9%) developed culture-positive endophthalmitis. CONCLUSIONS: Significant morbidity is associated with IVTA injection; clinicians should be aware when considering treatment options.

Adult↗
PubMed2005

Expanding role of local anaesthesia in vitreoretinal surgery.

PURPOSE: Local anaesthesia (LA) is increasingly common in vitreoretinal surgery. However, younger patients often have such surgery under general anaesthesia (GA). We reanalysed the anaesthetic practice for vitreoretinal surgery in our unit over a 19-month period. METHODS: A total of 1003 patients undergoing vitreoretinal surgery between August 2000 and February 2002 were studied. Type of surgery, patient pain score to anaesthesia and surgery, need for sedation and incidence of complications related to the local anaesthetic were recorded. Comparisons were made between this case series and previous data from our unit. RESULTS: In total, 920/1003 (91.7%) patients had LA. Total operations comprised 418 vitrectomies, 518 retinopexies with or without vitrectomy and 67 buckling procedures. More patients under the age of 35 years had LA than previously (60.2 vs 35.7%, P<0.001). In 920/920 (100%) of cases, LA was administered via intraconal injection, compared to 164/1221 (13.4%) of procedures previously. Significantly more patients under the age of 35 years required sedation (35.9%) than did older patients (19.2%). Overall, use of sedation was significantly increased since our previous study (20.2 vs 7.8%). Anaesthesia and surgery were well tolerated by patients. There were no cases of orbital haemorrhage or ocular perforation. Complications included bradycardia requiring atropine 1/920 (0.1%) and chemosis 88/920 (9.6%). CONCLUSIONS: LA is well tolerated and effective even in younger patients. Sedation may well be required in younger patients and for procedures involving scleral buckling. The main indication for GA was patient preference. Despite this, such patients accounted for only 5.2% of the total.

Adolescent↗
PubMed2001

Transpupillary thermotherapy (TTT) for the treatment of choroidal neovascularisation.

AIM: To assess the effectiveness of transpupillary thermotherapy (TTT) for the treatment of classic and occult choroidal neovascularisation (CNV). METHOD: In a retrospective, case selected, open label trial 44 eyes of 42 patients with CNV secondary to age related macular degeneration (ARMD) were studied. 44 eyes with angiographically defined CNV were treated with diode laser (810 nm) TTT. Laser beam sizes ranged between 0.8 and 3.0 mm and power settings between 250-750 mW. Treatment was given in one area for 1 minute, the end point being no visible change, or a slight greying of the retina. Outcome was assessed with Snellen visual acuity and clinical examination; in 24/44 patients angiographic follow up was available. RESULTS: 12 predominantly classic CNV and 32 predominantly occult membranes were followed up for a mean of 6.1 months (range 2-19). Mean change in vision for classic membranes was -0.75 (SD 1.75) Snellen lines and occult membranes was -0.66 Snellen lines (2.1) (p>0.05). Predominantly classic membranes were closed in 75% (95% CI: 62.5-87.5) of eyes, remained persistent in 25% (95% CI: 12.5-37.5); no recurrences occurred. Predominantly occult membranes were closed in 78% (95% CI: 70.1-85.3) of eyes, remained persistent in 12.5% (95% CI: 6.6-18.5), and were recurrent in 5.1% (95% CI: 4.2-14.3). CONCLUSIONS: Transpupillary thermotherapy is a potential treatment for CNV. It is able to close choroidal neovascularisation while maintaining visual function in patients with classic and occult disease. Further trials of TTT are needed to compare this intervention with the natural history and other treatment modalities.

Aged↗
PubMed2001

Local anaesthesia for 1221 vitreoretinal procedures.

BACKGROUND: Vitreoretinal (VR) surgery has been increasingly performed under local anaesthesia (LA) in this unit. The results of an audit monitoring this change are presented. METHODS: Data were collected on 1497 patients including type, volume, and position of the anaesthetic block, type of surgery, complications, and patient reactions. RESULTS: 1221/1479 (82%) patients had LA. They were older than those having general anaesthesia (GA) 63.5 years v 45.9 years; 146 (10.6%) blocks were intracone, 130 (10.6%) peribulbar, and 927 (75.9%) combined. Operations included 436 vitrectomies, 545 retinopexy with or without vitrectomy, and 238 buckling procedures. Some pain was felt by 9.4%, 8.8%, and 19.7% of patients during vitrectomy, retinopexy with or without vitrectomy, and buckling surgery respectively. CONCLUSION: Local anaesthesia for VR surgery is well tolerated by patients, being effective throughout longer and more stimulating ocular surgery.

Adolescent↗
PubMed2001

Effect of digital image compression on screening for diabetic retinopathy.

BACKGROUND/AIMS: Digital imaging is widely used for diabetic retinopathy screening. The storage and transmission of digital images can be facilitated by image compression. The authors aimed to assess the effect of image compression on the accuracy of grading diabetic retinopathy. METHODS: Forty nine 35 mm transparencies (17 with no retinopathy, eight with background, five with preproliferative, and 19 with proliferative retinopathy) were digitised and subjected to JPEG compression by 90%, 80%, 70%, and 0%. The 196 images were randomised and graded on a portable computer. Two masked graders assessed the images for grade of retinopathy and image quality (0-10). The sensitivity and specificity of retinopathy grading were calculated with a weighted kappa for grading agreement between levels of compression. RESULTS: The sensitivity of retinopathy grading was reduced by JPEG compression. At 90%, 80%, 70%, and 0% compression the sensitivities were 0.38, 0.50, 0.65, and 0.72, respectively; the specificity results were 1.00, 1.00, 0.83, and 0.84, respectively; and the weighted kappa scores were 0.60, 0.75, 0.77, and 0.84, respectively. The quality scores for 90%, 80%, 70%, 0% compression were 2.9 (SD 1.1, 95% CI; 2.7-3.2), 4.6 (SD 1.1, 95% CI; 3.0-5.6), 5.8 (SD1.5, 95% CI 5.0-6.6), 6.3 (SD1.4, 95% CI; 5.4-7.2) (p<0.01 for each intergroup comparison). CONCLUSION: The results demonstrate significant loss of sensitivity to the features of diabetic retinopathy with JPEG compression; this was compounded by the thin film transistor (TFT) screen. The authors found the quality of uncompressed images on TFT screens too poor to give grading sensitivities which reach current guidelines for diabetic retinopathy screening.

Computer Terminals↗
PubMed2000

Clinical evaluation of 'local contrast enhancement' for oral fluorescein angiograms.

PURPOSE: To describe and assess the clinical impact of 'local contrast enhancement' on oral fluorescein angiograms. METHODS: Oral fluorescein angiograms (OFA) were performed on 12 patients with a range of diabetic retinopathy. The digital images were processed using two enhancement techniques: histogram equalization, a widely available method; and 'local contrast enhancement'. Twelve control images and 24 enhanced images were randomised and subjectively graded for clarity between 1 and 100 on a visual analogue scale by two masked observers. A score of 50% was chosen as the cut-off for clinically useful images. RESULTS: The mean score for the unenhanced images was 38.8% (SD 19.4); the histogram equalization performed better at 54.7% (SD 10.0) (p = 0.016) and 'local contrast enhancement' at 69.4% (SD 13.6) (p < 0.001). These results equate to a 14.7% improvement in comparison with histogram equalization and a 30.3% improvement with the 'local contrast enhancement' technique. All the 'local contrast enhancement' images were clinically useful, compared with 58.3% of the histogram equalization images (chi 2 2.08, p = 0.2), and 33.3% of the control images (chi 2 = 6.75, p = 0.01). CONCLUSION: This pilot study has demonstrated the power of 'local contrast enhancement' techniques for low-contrast fluorescein angiograms. Using 'local contrast enhancement' oral fluorescein angiograms can give high-quality images and may allow safer patient investigation.

Administration, Oral↗
PubMed2000

Screening for CMV retinitis using chromatic discrimination thresholds and achromatic contrast sensitivity.

BACKGROUND: Many patients with cytomegalovirus retinitis (CMVR) are unaware of visual disturbance so screening is advocated for patients with HIV and low CD4 counts. Many tests of retinal function have been recommended but few are effective at detecting CMVR. We assess the potential of chromatic discrimination thresholds and achromatic contrast sensitivity as screening tests for patients with CMVR. METHOD: 11 HIV+ patients with CMVR, 16 age matched HIV+ patients, and 29 age matched controls were recruited. Visual acuity, chromatic discrimination thresholds, and achromatic contrast sensitivity were measured. Fundal examination was performed by slit lamp biomicroscopy for HIV+ patients. Those with CMVR were photographed and the CMVR graded from the photographs. RESULTS: Loss of chromatic discrimination was found in patients with CMVR (tritan p<0.0005, red/green p<0.05). The same group had deterioration in achromatic contrast sensitivity at 2.2, 3.4, and 10 cpd (p<0.05). There was correlation between the zone of CMVR with chromatic gratings (tritan r=0.83, p<0.005). No statistically significant difference was found between the HIV+ patients and the controls for all tests (p>0.1). CONCLUSIONS: HIV+ patients with CMVR have a loss of chromatic discrimination and achromatic contrast sensitivity and this may be used to screen HIV+ patients for CMVR.

AIDS-Related Opportunistic Infections↗
PubMed1999

Cerebral metastasis presenting with altitudinal field defect.

A 75-year-old man presented with a unilateral inferior altitudinal visual field defect and a history of weight loss and night sweats. The acuity in the affected eye was 20/200, otherwise his ocular examination was normal. Neuroimaging demonstrated a post-fixed chiasm, with a frontal metastasis compressing the intracerebral portion of the optic nerve. A chest x-ray showed classical cannon ball lesions, secondary to malignant melanoma. This is the first case report of an intracerebral tumor producing an inferior altitudinal field defect.

Aged↗
PubMed1994

Retinal blood flow changes during pregnancy in women with diabetes.

PURPOSE: To study retinal blood flow (RBF) during pregnancy in subjects with and without diabetes and to relate the changes to progression in diabetic retinopathy. METHODS: RBF in a major temporal retinal vein was measured, where possible, during all three trimesters (T1 to T3) and the postpartum period (PP) using laser Doppler velocimetry (measuring velocity [V]) and monochromatic fundus photographs (measuring diameter [D]). RESULTS: In the subjects without diabetes (n = 19), no significant change in RBF was demonstrated. V was significantly greater in T3 than in PP (P = 0.01). D was significantly smaller in T1 to T3 than in PP (P < or = 0.01). RBF in the subjects with diabetes was significantly higher in T2 and T3 than in PP (P < 0.05). V increased from T1 to T2 (P = 0.04) and decreased from T2 to PP (P = 0.001) and from T3 to PP (P = 0.002). The only significant change in D was a smaller value in T1 than in PP (P = 0.003). However, it was only those subjects whose DR progressed (n = 11) who had a significant increase in RBF during pregnancy (P = 0.0001). CONCLUSIONS: These data suggest that the hyperdynamic circulation present in pregnancy led to compensatory retinal vessel constriction (autoregulation) in the group without diabetes; this was largely absent in the patients with diabetes, with resultant increase in retinal blood flow associated with worsening retinopathy. This finding lends further support to the hypothesis that increased retinal blood flow is a pathogenic mechanism for diabetic retinopathy.

Adult↗
PubMed1992

Retinal vessel measurement: comparison between observer and computer driven methods.

A method of semi-automated image analysis for the measurement of retinal vessel diameters is described. This was compared with an observer-driven method for reproducibility and accuracy. The coefficient of variation for the data from the semi-automated method was 1.5-7.5% (depending on the vessel diameter) compared to 6-34% with the observer-driven method. The mean vessel diameters using the observer-driven method tended to be higher; however, this did not reach significance. The speed and low inter- and intra-observer variability for the semi-automated method make it a useful technique for measuring retinal blood vessel diameters. A larger variability was found between photographs taken at different times. This may be due to changes in retinal vessel diameter with changes in retinal perfusion pressure during the cardiac cycle.

Diabetic Retinopathy↗
PubMed1977

A simulated patient-physician encounter using a talking computer.

Computer-based clinical simulations provide a means for evaluating the information-gathering and patient-management competencies of physicians. The need for expensive computer terminals has restricted physician use of these simulations. This computer-based program permits physicians to complete computer-based encounters using a standard touch-tone telephone.

Clinical Competence↗
PubMedDate not supplied

The effect of beta blockers on retinal blood flow in diabetic patients.

The effect of a single oral dose of propanolol 80 mg, dilevalol 200 mg, salbutamol 4 mg, and placebo on the systolic (BPs), diastolic blood (BPd), intraocular pressure (IOP), on retinal vessel diameter (D), blood velocity (Vmax) and volumetric retinal blood flow (RBF), was measured at baseline, 90 minutes and three hours after administration in normotensive diabetic volunteers. These drugs were chosen to demonstrate a range of beta receptor activity. Propanolol is a non-specific beta blocker, affecting beta 1 and beta 2 receptors, dilevalol has beta 1 antagonist and beta 2 agonist effects and salbutamol has beta 2 agonist effects. Retinal blood flow was measured by bidirectional laser Doppler velocimetry (BLDV) and red free photography. Dilevalol reduced the mean BPs by 10.4 mmHg (SD 4.2, P less than 0.05), the mean BPd by 7 mmHg (SD 3.8, P less than 0.05), whereas propanolol, salbutamol and placebo had no significant effect. Propanolol reduced the mean intraocular pressure by 4.88 mmHg (SD 1.8, P less than 0.01). No treatment had a significant effect on retinal perfusion pressure. In all treatments the vessel diameter and volumetric flow remained unchanged, and there was no significant difference between the treatments. The mechanisms of action of these drugs are analysed and the possible implications of their use in patients with retinal disease are discussed.

Administration, Oral↗