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Biomedical subjects

S A Vernon

Publications and source records attributed to S A Vernon.

At least 19 recordsLinked to original sources
PubMed2007

Mean deviation fluctuation in eyes with stable Humphrey 24-2 visual fields.

AIM: To describe the expected fluctuation in the mean deviation (MD) scores on a large, long-term series of stable visual field reports for particular grades of defect in order to give clinicians an aid to the correct diagnosis of glaucomatous progression. METHOD: Visual field reports of subjects with five reliable consecutive Humphrey 24-2 visual fields, recorded over a period of at least 3 years, were scored using the Advanced Glaucoma Intervention Study (AGIS) system. The AGIS scores of the first and last visual fields were required to be identical. RESULTS: A total of 202 eyes from 202 patients were used in the study, with a total of 1010 visual fields being used in the analysis. Visual fields with no defect (AGIS score 0) had a 99% confidence interval (CI) of 0.3 dB, mild defects 0.4 dB, moderate defects 0.8 dB, severe 1 dB, and 1.3 dB for end-stage defects when considering variation of MD scores. Using a one-way ANOVA incorporating all stages showed very little fluctuation throughout the series (P=0.96). The correlation between the CI and grade of field defect showed a good positive correlation (r=0.7, P=0.0003) indicating an increase in CI as field defects worsen. CONCLUSION: When considering a series of reliable visual fields in a stable eye, one should expect only very little fluctuation in the MD, indicating that an increase in the MD beyond that of the 99% CI described may suggest progression. The reliability indices of the visual field test should be regarded as a primary consideration when assessing visual fields.

Age Factors↗
PubMed2006

The -174G/C interleukin-6 promoter polymorphism influences the development of macular oedema following uncomplicated phacoemulsification surgery.

AIM: To determine whether the functional -174 G/C interleukin-6 gene polymorphism is a risk factor for the development of cystoid macular oedema (CMO) following routine uncomplicated phacoemulsification surgery in patients with no established risk factors. METHODS: A total of 40 patients who underwent routine phacoemulsification surgery as part of a randomised controlled trial comparing the use of postoperative steroid drops against a single sub-tenon injection of triamcinolone were genotyped for the IL-6 -174G/C polymorphism. All patients underwent fluorescein angiography at 30 days and anterior chamber flare measurements pre-operatively and at day 1, 7, and 30. RESULTS: Angiographic CMO developed in 14 patients of the 40 studied. 9 out of the 14 patients carried the GG genotype (Fisher's exact test P=0.05, Hazard ratio for GG genotype; 4.05 (1.02-16.00)). There was no difference in flare measurements between the GG and Non-GG (GC/CC) group. The two groups were otherwise well matched in terms of age, sex, phacoemulsification energy used intraoperatively, and proportion of patients receiving postoperative triamcinolone or steroid drops. CONCLUSION: The -174G/C interleukin-6 promoter gene variant appears to modulate the response to phacoemulsification surgery and to influence the development of postoperative CMO. These data suggest a genetic predisposition to this complication.

Aged↗
PubMed2006

Intravitreal triamcinolone will cause posterior subcapsular cataract in most eyes with diabetic maculopathy within 2 years.

PURPOSE: To determine the incidence of cataract following intravitreal triamcinolone (IVTA) for diabetic macular oedema. METHODS: Prospective, non-randomised, interventional cohort case series. A total of 27 eyes of 27 patients with diabetic macular oedema received an intravitreal injection of 4 mg (0.1 ml) of triamcinolone acetonide inferotemporally through the pars plana under direct vision. In 20 patients the fellow eye served as control, whereas seven patients had both eyes injected (not simultaneously). Seven patients had a repeat (second) injection in the same eye. The main outcome measures were cataract and intraocular pressure (IOP) rise of at least 5 mmHg (IOP responder). RESULTS: The mean follow-up time was 18.9 months (range 13-29 months). A total of 22 (81%) of 27 eyes developed cataract during the follow-up period, of which 20 (74%) were posterior subcapsular in nature. None of the 20 uninjected fellow eyes developed posterior subcapsular cataract. Mean time to cataract formation was 16.2 months. In the seven patients who had both eyes injected, mean time to cataract formation was 16.5 and 17.1 months in the first and second eye, respectively. Mean time to cataract formation in seven eyes receiving a repeat second injection was 17.9 months. There was no significant difference in cataract formation between IOP responders (85%) and non-responders (79%) (P=1.00, Fisher's exact test). Uneventful cataract surgery was performed in six eyes of five patients. CONCLUSION: This study demonstrates that given appropriate long-term follow-up, the majority of patients, even after a single IVTA injection, will go on to develop cataract, of which posterior subcapsular will be by far the most common.

Adult↗
PubMed2006

Eyetrack (ET) vs the conventional paper record (CPR): a study comparing the accuracy and speed of data retrieval from glaucoma patient records.

PURPOSE: To compare patient data retrieval between electronic patient record systems (Eyetrack) and conventional paper records (CPRs). METHODS: A total of 20 long term glaucoma patient records held on Eyetrack were randomised into two collections with 10 CPRs and 10 Eyetrack records in each collection. The Eyetrack records of one collection were the CPRs of the other collection and vice versa. Four doctors, as two groups, were assessed on a separate collection of records. The time taken to answer 10 questions and the accuracy were assessed. Comparison was made of the answers between the two formats. A month later each group was assessed on the 10 CPRs of the other collection. An expert Eyetrack user was assessed on only the 20 Eyetrack notes. Comparison was made between the 20 CPRs the doctors were assessed on and the 20 eyetrack records. RESULTS: In the first comparison, the mean time for all the doctors to answer the questions on a CPR was 324.4(+/-106.0) s compared to 104.8(+/-34.0) s for Eyetrack(Mann-Whitney, P<0.01). Mean accuracy for a CPR was 84.0%(+/-13.0%) compared to 98.0%(+/-4.0%) for Eyetrack(Mann-Whitney, P<0.01). Comparing the expert Eyetrack user with the CPR showed a mean time for Eyetrack of 96.6(+/-34.8) s compared with 283.7(+/-63.9) s for CPR(Mann-Whitney, P<0.0001). Mean accuracy for Eyetrack was 97.5%(+/-7.2%) compared to 82.0%(+/-8.7%) for CPRs(Mann-Whitney, P<0.0001). CONCLUSIONS: An improvement of 3 min 40 s per record was observed with Eyetrack. Accuracy was also improved. Similar results were also found comparing an expert Eyetrack user with CPRs.

Glaucoma↗
PubMed2006

Longitudinal glaucoma screening for siblings of patients with primary open angle glaucoma: the Nottingham Family Glaucoma Screening Study.

AIMS: To assess the prevalence and cumulative incidence of open angle glaucoma (OAG) in a cohort group of siblings of OAG probands. METHODS: Between 1994 and 2003, a group of siblings of OAG probands underwent both initial and follow up standardised ophthalmic examinations. Siblings were classified as "definite glaucoma" (primary OAG (POAG) and normal tension glaucoma (NTG)), "glaucoma suspects" (NTG suspects or ocular hypertension (OHT)), and normal. The prevalence and cumulative incidence of OAG over the follow up interval were calculated. RESULTS: At the initial study, 271 siblings (mean age 63.6 years; female to male ratio 1.2) from 156 probands were examined. 32 (11.8%) were classified as definite glaucoma and 15 (5.5%) as suspects. In the follow up study, 157 of the 224 "normal" siblings from the initial study were examined (mean interval from initial study 7.0 (SD 1.0) years). 11 (7%) were classified as definite glaucoma and 30 (19.1%) as suspects. There were significant trends of increasing prevalence and incidence of OAG with age and a lifetime risk estimated at approximately 20% by age 70. CONCLUSION: Siblings of glaucoma patients have an increased risk of developing glaucoma and the risk increases with age. An effective and repeated screening programme should be considered for this high risk group.

Age Distribution↗
PubMed2006

Detecting glaucoma with RADAAR: the Bridlington Eye Assessment Project.

AIMS: To develop a diagnostic algorithm using rim/disc area asymmetry ratio (RADAAR) to discriminate between normal and glaucomatous eyes using the Heidelberg retina tomograph (HRT). METHODS: RADAAR was calculated by dividing rim/disc area ratio of the larger disc by that of the smaller disc. RADAAR normal tolerances in each disc sector were generated using 611 population based normal elderly individuals (mean age 72.5 years). Overall status for each individual was equal to the worst disc sector. Sensitivity was assessed in 45 patients with open angle glaucoma. RESULTS: RADAAR variance was significantly greater in glaucoma compared with normality in all disc sectors (p<0.001). Normal RADAAR limits were not dependent on age or sex. Overall, at the 99th percentile limit, the diagnostic algorithm's specificity was 95.1% with a sensitivity of 55.6%. Males with glaucoma showed greater RADAAR variance than females. Corresponding sensitivity of the diagnostic algorithm was 63.0% and 44.4% in males and females respectively, although this difference was not statistically significant (p = 0.43). CONCLUSION: The RADAAR diagnostic algorithm detected glaucoma with moderate sensitivity but was limited by significant numbers of glaucoma patients with symmetrical optic disc changes. RADAAR may have greater sensitivity in males than in females although this requires confirmation in further studies.

Aged↗
PubMed2005

Risk management strategies following analysis of cataract negligence claims.

INTRODUCTION: Clinical governance and risk management is very important in today's clinical practice. Cataract surgery is one of the most common procedures performed in the NHS, with around 200,000 operations per year. In order to help minimise the frequency of negligence claims, we performed a collaborative study to analyse claims relating to cataract surgery, dealt with by the defence organisations of England, Scotland, Wales, and Northern Ireland. MATERIALS AND METHODS: All claims dealt with by the Medical Defence Union, the Medical Protection Society, and the Medical and Dental Defence Union of Scotland from January 1990 to December 1999, were analysed by three ophthalmologists with at least 5 years' speciality experience. Recurrent themes were identified and claims were grouped by major causative factor. The findings were discussed by a panel compromising the authors in conjunction with the defence unions and risk management strategies were designed. RESULTS: There were 96 claims within the 10- year period analysed. Of these, the largest group (52) pertained to claims that related to accepted complications of cataract surgery. The remainder comprised two groups: 'Medical Errors' (anaesthetic, surgeon, and biometry) and 'Other Claims' comprising subjective complaints, pain and poor visual outcome. A total of 16 claims had been settled by May 2002, 45 are ongoing and 35 have closed without settlement. CONCLUSIONS: The majority of claims pertained to well-recognised complications of cataract surgery. If these risks are adequately explained to the patient before surgery and if the care provided reaches a standard acceptable to a responsible body of professional opinion, all such claims should be defensible. Good visual outcome does not protect against litigation.

Cataract Extraction↗
PubMed2005

Is poor life expectancy a predictive factor in the progression of primary open angle glaucoma?

AIM: To investigate the disease progression and final visual outcome of glaucoma patients with poor life expectancy, compared to matched patients with a longer life expectancy. METHOD: Visual fields at diagnosis and at the last ophthalmic appointment before death were analysed for glaucoma patients referred between 1991 and 1995, and deceased before the end of 2001. These patients were matched to the patients living beyond 2001. Functional vision was also assessed, and classified as better than the NHS partial sighted criteria. RESULTS: A total of 61 deceased patients were identified, resulting in 40 matched pairs. In all, 6.5% of the patients with poor life expectancy progressed from functional vision to beyond partial sighted criteria, and none of the matched patients progressed to this extent. At final assessment an association between poor life expectancy and progression beyond functional vision was found existing (P = 0.02), with a lesser association at diagnosis (P = 0.06). Visual field scores of the matched pairs who had test results available for both initial and final assessment (n = 23 pairs) showed no statistically significant difference between the two groups at diagnosis (P = 0.52); However, a significant difference at final the assessment did exist (P = 0.042). No difference between the initial (off medication) intraocular pressures (IOPs) was found (P = 0.82). At the final assessment a significant difference existed (P = 0.025), with the surviving group having a higher final mean pressure (15.9 mmHg, SD 2.8, vs 18.3 mmHg, SD 4.9). CONCLUSION: Patients with poor life expectancy progressed more than the matched surviving patients, when measured from an initially similar position, despite better IOP control.

Aged↗
PubMed2005

Intravitreal triamcinolone improves vision in eyes with chronic diabetic macular oedema refractory to laser photocoagulation.

PURPOSE: To evaluate the clinical and visual outcome of an intravitreal injection of triamcinolone in patients with diabetic macular oedema refractory to laser treatment. MATERIAL AND METHODS: Prospective, interventional nonrandomised case series of 24 eyes of 24 patients that underwent intravitreal injection of 4 mg triamcinolone for chronic diabetic macular oedema refractory to previous laser treatment. All patients had best corrected visual acuity (bcva) on the LogMAR scale, near vision, slit-lamp biomicroscopy for the presence of clinically significant macular oedema, and intraocular pressure check at 1, 3, and 6 months. RESULTS: The average duration of macular oedema before the injection was 38.2 months (range=6-120 months) with the mean number of laser treatments before the injection being 2.2 (range=1-5). The visual acuity improved in 19 of the 23 (83%) eyes at 1 month, 16 of the 21 eyes (76%) at 3 months and six of 11 eyes (55%) at 6 months follow-up. The mean bcva improved by an average of 10, nine, and six letters, respectively, compared to the baseline at 1, 3, and 6 months (P=0.0002 at 1 month and 0.001 at 3 months with the Wilcoxon signed-ranked test). The intraocular pressure rose by an average of 2.4, 2.8, and 2.7 mmHg at the same follow-up visits. CONCLUSION: Intravitreal triamcinolone appears to be promising in the short term, for improving the vision in eyes with chronic diabetic macular oedema unresponsive to conventional laser treatment. Randomised controlled trials utilising varying doses of steroid are now required to define optimum treatment regimens.

Aged↗
PubMed2005

Improved visual acuity and macular thickness 1 week after intravitreal triamcinolone for diabetic macular oedema.

PURPOSE: To evaluate the clinical and volumetric improvement 1 week after an injection of intravitreal triamcinolone acetonide in eyes with diabetic macular oedema. METHODS: Seven phakic eyes of seven diabetic patients diagnosed with clinically significant macular oedema were treated with a single 4-mg intravitreal injection of triamcinolone acetonide (0.1 ml). LogMAR best corrected visual acuity (logMAR BCVA), best corrected reading ability (RA), and central macular thickness (CMT) with optical coherence tomography (OCT) were assessed prior and 1 week subsequent to treatment. RESULTS: Mean improvement in logMAR BCVA was 0.146 (P=0.03). Mean reduction in CMT was 150.9 mum (P=0.02, Wilcoxon signed-rank test). Mean improvement in RA was 3 lines. CONCLUSION: Reduction in macular oedema was demonstrated on OCT at 1 week, in most cases associated with improvement in central visual function, in particular, reading ability. Total resolution of diabetic macular oedema may occur at 1 week following intravitreal steroid injection.

Aged↗
PubMed2004

Does the site of filtration influence the medium to long term intraocular pressure control following microtrabeculectomy in low risk eyes?

AIMS: To evaluate the influence of varying surgical site on the medium to long term intraocular pressure (IOP) control in patients undergoing unenhanced small flap trabeculectomy (microtrabeculectomy) in eyes at low risk of failure. METHODS: A retrospective non-concurrent analysis was performed on two cohorts of patients who underwent unenhanced microtrabeculectomy at different sites by a single surgeon (SAV). The first cohort of eyes was part of a trial to study the astigmatic effect of microtrabeculectomy (results published elsewhere) and all had flaps centred at the 12 o'clock meridian (superior flaps). The second cohort consisted of eyes with flaps created on either side of the 12 o'clock-that is, superonasal in left eyes and superotemporal in right eyes. All case notes were reviewed for the preoperative and presenting IOPs, the number and duration of antiglaucoma medication use preoperatively and, postoperatively, any intraoperative, early, or late postoperative complications. All IOPs measured at 6 months and then yearly intervals were recorded. The baseline characteristics and IOPs at each follow up were compared between the eyes with the superonasal and superotemporal flaps of the non-12 o'clock group against those with superior flaps in the 12 o'clock group up to a maximum of 72 months. Survival was assessed by the site of microtrabeculectomy, with failure considered as any IOP above 22 and 15 mm Hg with or without medications. RESULTS: All patients had a minimum follow up of 12 months and 12/17 patients in the 12 o'clock group and 17/28 in the non-12 o'clock group completed the full follow up of 72 months. The IOPs at all points in time were lower in the left eyes with superonasal flaps compared to both the superior and the superotemporal groups. This difference was statistically significant between the three groups to the end of 4 years (p = 0.001) and remains clinically significant thereafter with the mean last recorded IOPs of 15.9, 12.4 (p = 0.03), and 14.3 mm Hg in the superior, superonasal and superotemporal groups respectively, with a smaller mean number of drops in the non-12 o'clock group. Kaplan-Meier curves showed a significantly better outcome for the cutoff IOP of 15 mm Hg in the superonasal group (p = 0.003) compared with both the other groups. CONCLUSION: Eyes with superonasal flaps achieve and maintain lower IOPs when compared with both the superior and superotemporal flaps. The results suggest that, when a low target IOP is desired, the site of surgery in an unenhanced filtering procedure should be superonasally sited.

Aged↗