Susan P Mollan

Understanding idiopathic intracranial hypertension: mechanisms, management, and future directions

Idiopathic intracranial hypertension is a disorder characterised by raised intracranial pressure that predominantly affects young, obese women. Pathogenesis has not been fully elucidated, but several causal factors have been proposed. Symptoms can include headaches, visual loss, pulsatile tinnitus, and back and neck pain, but the clinical presentation is highly variable. Although few studies have been done to support evidence-based management, several recent advances have the potential to enhance understanding of the causes of the disease and to guide treatment decisions. Investigators of the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) reported beneficial effects of acetazolamide in patients with mild visual loss. Studies have also established weight loss as an effective disease-modifying treatment, and further clinical trials to investigate new treatments are underway. The incidence of idiopathic intracranial hypertension is expected to increase as rates of obesity increase; efforts to reduce diagnostic delays and identify new, effective approaches to treatment will be key to meeting the needs of a growing number of patients.

Postcataract endophthalmitis: Incidence and microbial isolates in a United Kingdom region from 1996 through 2004

PURPOSE: To investigate the incidence of endophthalmitis after cataract surgery, analyze the microbiologic spectrum of infecting organisms, and assess the diagnostic utility of an anterior chamber paracentesis and vitreous biopsy. SETTING: United Kingdom tertiary referral center used by 13 operating suites. METHODS: A retrospective noncomparative consecutive series comprised 105 postcataract endophthalmitis cases. RESULTS: The annual mean incidence of endophthalmitis over the study period was 0.099% (10/101 920), and there was no significant increase in the incidence during the study. The culture‐positive rate was 58.1% (61/105). Gram‐positive microbes were isolated in 93.4% of cases (57/61), with coagulase‐negative staphylococci accounting for 62.3% (38/61). Anterior chamber taps yielded positive cultures in 25.7% of cases, and vitreous biopsy was positive in 53.4%. CONCLUSIONS: The incidence of endophthalmitis in this region of the United Kingdom remained stable, with gram‐positive microbes accounting for 93.4% of the isolates. A combination of anterior chamber tap and vitreous biopsy should be performed in suspected cases of endophthalmitis.

Accuracy of Goldmann, ocular response analyser, Pascal and TonoPen XL tonometry in keratoconic and normal eyes.

Aim: The aim of this study was to evaluate the practicality and accuracy of tonometers used in routine clinical practice for established keratoconus (KC). Methods: This was a prospective study of 118 normal and 76 keratoconic eyes where intraocular pressure (IOP) was measured in random order using the Goldman applanation tonometer (GAT), Pascal dynamic contour tonometer (DCT), Reichert ocular response analyser (ORA) and TonoPen XL tonometer. Corneal hysteresis (CH) and corneal resistance factor (CRF), as calculated by the ORA, were recorded. Central corneal thickness (CCT) was measured using an ultrasound pachymeter. Results: The difference in IOP values between instruments was highly significant in both study groups (p<0.001). All other IOP measures were significantly higher than those for GAT, except for the Goldmann-correlated IOP (average of the two applanation pressure points) (IOPg) as measured by ORA in the control group and the CH-corrected IOP (corneal-compensated IOP value) (IOPcc) measures in the KC group. CCT, CH and CRF were significantly less in the KC group (p<0.001). Apart from the DCT, all techniques tended to measure IOP higher in eyes with thicker corneas. Conclusion: The DCT and the ORA are currently the most appropriate tonometers to use in KC for the measurement of IOPcc. Corneal factors such as CH and CRT may be of more importance than CCT in causing inaccuracies in applanation tonometry techniques.

Evolving evidence in adult idiopathic intracranial hypertension: pathophysiology and management

Idiopathic intracranial hypertension (IIH) is a rare but important disease associated with significant morbidity. There is an expected rise in prevalence in line with the escalating global burden of obesity. Modern revisions in the terminology and diagnostic criteria for IIH help guide clinicians in investigations and researchers in standardising recruitment criteria for clinical trials. The pathophysiology of IIH is incompletely characterised; suggested underpinning mechanisms include the role of cerebrospinal fluid regulation as well as metabolic and endocrinological perspectives. Recent treatment trials are providing insights into the management but debate still surrounds key areas in treatment. This review will provide an up-to-date discussion on the potential pathogenic mechanisms and management of IIH.

Efficacy of antiglaucoma fixed combination therapy versus unfixed components in reducing intraocular pressure: a systematic review

Aim: To evaluate the efficacy of the fixed combination ocular hypotensive therapies compared with their non-fixed components used concomitantly for lowering intraocular pressure (IOP) in glaucoma and ocular hypertension. Methods: A systematic review of the literature, up to May 2007, without limits on year or language of publication was performed. Seven randomised controlled trials (n = 2,083 eyes) were identified. Assessment of methodological quality was made using standardised criteria. Results were pooled quantitatively using meta-analysis methods, and statistical analysis was performed using STATA software. The difference in mean intraocular pressure (mm Hg) from baseline between the fixed combination and non-fixed component therapies was compared. Non-inferiority in terms of efficacy was set at an upper confidence limit of ⩽1.5 mm Hg for all time points (hour (Hr)0, Hr2 and Hr8) and evaluated at 12 weeks. Safety was evaluated from data on adverse events as reported in the included studies. Results: Of the 679 abstracts identified, seven randomised controlled trials met the selection criteria. The quality scores of included studies were high (mean of 29.4, maximum score 30). The mean differences (95% CI) and p values at 12 weeks were as follows: 0.200 mm Hg, (CI −0.106 to 0.507), p = 0.20 for Hr0, 0.393 mm Hg (CI 0.038 to 0.747), p = 0.03 for Hr2 and 0.501 mm Hg (CI 0.156 to 0.846), p = 0.004 for Hr8. Although both Hr2 and Hr8 showed statistical significance favouring the non-fixed combinations, the non-inferiority measure ⩽1.5 mm Hg upper confidence limit was not exceeded. Conclusions: Fixed combination therapies are equally safe and effective at lowering IOP as their non-fixed components administered concomitantly.

A practical approach to, diagnosis, assessment and management of idiopathic intracranial hypertension

Adult patients who present with papilloedema and symptoms of raised intracranial pressure need urgent multidisciplinary assessment including neuroimaging, to exclude life-threatening causes. Where there is no apparent underlying cause for the raised intracranial pressure, patients are considered to have idiopathic intracranial hypertension (IIH). The incidence of IIH is increasing in line with the global epidemic of obesity. There are controversial issues in its diagnosis and management. This paper gives a practical approach to assessing patients with papilloedema, its investigation and the subsequent management of patients with IIH.

Incidence of endophthalmitis following vitreoretinal surgery

Aim The purpose of this study was to investigate the incidence of postvitreoretinal surgery endophthalmitis in a UK tertiary referral centre. Methods Two cases that met the clinical criteria of endophthalmitis following conventional 20-gauge vitreoretinal surgery were included in this retrospective, noncomparative, consecutive case series. Results The incidence of endophthalmitis between 1 April 1997 and 30 November 2004 was 0.038% (n = 2/5,278). Conclusion The incidence of endophthalmitis following pars plana vitrectomy remains low.

Headache determines quality of life in idiopathic intracranial hypertension.

BackgroundThe effect of idiopathic intracranial hypertension (IIH) on quality of life (QOL) is poorly understood. Our objectives were to compare QOL in IIH to the normal UK population; to investigate QOL changes with treatment of IIH, using a weight loss intervention, and to determine which clinical factors influence QOL.MethodsThis was a prospective cohort evaluation of QOL, using the 36-Item Short Form (SF-36) Health Survey questionnaire, before and after a therapeutic dietary intervention which resulted in significant reduction in body mass index (BMI), intracranial pressure (ICP), papilloedema, visual acuity, perimetric mean deviation (Humphrey 24–2) and headache (six-item headache impact test (HIT-6) and headache diary). Baseline QOL was compared to an age and gender matched population. The relationship between each clinical outcome and change in QOL was evaluated.ResultsAt baseline, QOL was significantly lower in IIH compared to an age and gender matched population in most domains, p < 0.001. Therapeutic weight loss led to a significant improvement in 10 out of 11 QOL domains in conjunction with the previously published data demonstrating significant improvement in papilloedema, visual acuity, perimetry and headache (p < 0.001) and large effect size. Despite significant improvement in clinical measures only headache correlated significantly (p < 0.001) with improving QOL domains.ConclusionsQOL in IIH patients is significantly reduced. It improved with weight loss alongside significant improvement in clinical measures and headache. However, headache was the only clinical outcome that correlated with enhanced QOL. Effective headache management is required to improve QOL in IIH.

Does use of isotretinoin rule out a career in flying

Aim: To evaluate whether previous isotretinoin use induces permanent, measurable, and clinically significant abnormalities in night vision such that flying is precluded, and whether potential military and civilian commercial aviators should be screened routinely. Methods: A retrospective, non-interventional, consecutive case series of 47 individuals with a confirmed history of oral isotretinoin use were compared to 20 age and sex matched controls. Results: 47 individuals (44 males and three females), age range 17–33, underwent Goldmann-Weekers dark adaptation (DA) and standard electroretinogram (ERG) according to ISCEV protocols. 34 patients showed no abnormality in any parameters. Two patients had abnormal DA and ERGs. The mean scotopic ERG b wave amplitude of the isotretinoin group was 496.5 μV (SD 51.3 μV) compared with 501.7 μV (62.3.1 μV) among the controls. The group mean a:b ratio was 0.55 (0.04) compared to 0.69 (0.08) in the controls. Conclusion: Previous use of isotretinoin may have caused retinal toxicity in two subjects and laboratory evidence of night blindness in 11 further subjects. One subject had subclinical changes remaining in the ERG 96 months after cessation of isotretinoin. This may justify the directed use of electrophysiological screening in professions that are night vision critical.

The relationship between measurement method and corneal structure on apparent intraocular pressure in glaucoma and ocular hypertension

PURPOSE To analyse the relationship between measured intraocular pressure (IOP) and central corneal thickness (CCT), corneal hysteresis (CH) and corneal resistance factor (CRF) in ocular hypertension (OHT), primary open-angle (POAG) and normal tension glaucoma (NTG) eyes using multiple tonometry devices. METHODS Right eyes of patients diagnosed with OHT (n=47), normal tension glaucoma (n=17) and POAG (n=50) were assessed. IOP was measured in random order with four devices: Goldmann applanation tonometry (GAT); Pascal dynamic contour tonometer (DCT); Reichert ocular response analyser (ORA); and Tono-Pen XL. CCT was then measured using a hand-held ultrasonic pachymeter. CH and CRF were derived from the air pressure to corneal reflectance relationship of the ORA data. RESULTS Compared to the GAT, the Tonopen and ORA Goldmann equivalent (IOPg) and corneal compensated (IOPcc) measured higher IOP readings (F=19.351, p<0.001), particularly in NTG (F=12.604, p<0.001). DCT was closest to Goldmann IOP and had the lowest variance. CCT was significantly different (F=8.305, p<0.001) between the 3 conditions as was CH (F=6.854, p=0.002) and CRF (F=19.653, p<0.001). IOPcc measures were not affected by CCT. The DCT was generally not affected by corneal biomechanical factors. CONCLUSION This study suggests that as the true pressure of the eye cannot be determined non-invasively, measurements from any tonometer should be interpreted with care, particularly when alterations in the corneal tissue are suspected.