Quantitative estimation of retinal nerve fiber layer height in glaucoma and the relationship with optic nerve head topography and visual field

Purpose: The authors estimated the retinal nerve fiber layer height (RNFLH) measurements in patients with glaucoma compared with those in age-matched healthy subjects as obtained by the laser scanning tomography and assessed the relationship between RNFLH measurements and optic and visual field status. Methods: Parameters of optic nerve head topography and RNFLH were evaluated in 125 eyes of 21 healthy subjects and 104 patients with glaucoma using the Heidelberg Retina Tomograph ([HRT] Heidelberg Engineering GmbH, Heidelberg, Germany) for the entire disc area and for the superior 70°(50°temporal and 20°nasal to the vertical midline) and inferior 70°sectors of the optic disc. The mean deviation of the visual field, as determined by the Humphrey program 24-2 (Humphrey Instruments, Inc., San Leonardo, CA, U.S.A) was calculated in the entire field and in the superior and inferior Bjerrum area. Result: Retinal nerve fiber layer height parameters (mean RNFLH and RNFL cross-sectional area) were decreased significantly in patients with glaucoma compared with healthy individuals. Retinal nerve fiber layer height parameters was correlated strongly with rim volume, rim area, and cup/disc area ratio. Of the various topography measures, retinal nerve fiber layer (RNFL) parameters and cup/disc area ratio showed the strongest correlation with visual field mean deviation in patients with glaucoma. Conclusion: Retinal nerve fiber layer height measures were reduced substantially in patients with glaucoma compared with age-matched healthy subjects. Retinal nerve fiber layer height was correlated strongly with topographic optic disc parameters and visual field changes in patients with glaucoma.

Interpretation on Humphrey's visual field tests. Is it glaucoma?

This article describes a step-wise approach for the understanding and interpretation of Humphrey's SITA visual field tests. The goal of this article is to help the reader to differentiate between non-specific abnormalities of the visual field and changes of the visual field that are suggestive of glaucoma.

Influence of YAG laser posterior capsulotomy on preexisting glaucoma

Purpose. To evaluate the effects of a YAG laser posterior capsulotomy on intraocular pressure (IOP) in glaucoma patients. Methods. We retrospectively studied 69 patients who underwent posterior capsulotomy following cataract or combined cataract-glaucoma surgery and who had a minimum follow-up of six months. We assessed IOP control, number of glaucoma medications required, and need for additional glaucoma surgery following capsulotomy as clinical outcomes. We defined an "unfavorable result" as: a =5 mm Hg sustained rise in IOP, a need for additional glaucoma medications, and/or a need for additional glaucoma surgery. We calculated Kaplan-Meier event rate curves for these "unfavorable results." Mean follow-up was 24.4 ± 12.3 months. Results. 6.3% of patients had an IOP rise of =5 mm Hg one hour post capsulotomy. The actuarial (Kaplan-Meier) rate of any "unfavorable result" was 11.6% at 4 months, 38.1% at 12 months, 46.1% at 24 months, and 52.1% at 36 months following capsulotomy. Conclusions. Progression of glaucoma after YAG capsulotomy is common and may be accelerated by the laser procedure.

The clinical effectiveness and cost-effectiveness of screening for open angle glaucoma:A systematic review and economic evaluation

Objectives: To assess whether open angle glaucoma (OAG) screening meets the UK National Screening Committee criteria, to compare screening strategies with case finding, to estimate test parameters, to model estimates of cost and cost-effectiveness, and to identify areas for future research. Data sources: Major electronic databases were searched up to December 2005. Review methods: Screening strategies were developed by wide consultation. Markov submodels were developed to represent screening strategies. Parameter estimates were determined by systematic reviews of epidemiology, economic evaluations of screening, and effectiveness (test accuracy, screening and treatment). Tailored highly sensitive electronic searches were undertaken. Results: Most potential screening tests reviewed had an estimated specificity of 85% or higher. No test was clearly most accurate, with only a few, heterogeneous studies for each test. No randomised controlled trials (RCTs) of screening were identified. Based on two treatment RCTs, early treatment reduces the risk of progression. Extrapolating from this, and assuming accelerated progression with advancing disease severity, without treatment the mean time to blindness in at least one eye was approximately 23 years, compared to 35 years with treatment. Prevalence would have to be about 3-4% in 40 year olds with a screening interval of 10 years to approach cost-effectiveness. It is predicted that screening might be cost-effective in a 50-year-old cohort at a prevalence of 4% with a 10-year screening interval. General population screening at any age, thus, appears not to be cost-effective. Selective screening of groups with higher prevalence (family history, black ethnicity) might be worthwhile, although this would only cover 6% of the population. Extension to include other at-risk cohorts (e.g. myopia and diabetes) would include 37% of the general population, but the prevalence is then too low for screening to be considered cost-effective. Screening using a test with initial automated classification followed by assessment by a specialised optometrist, for test positives, was more cost-effective than initial specialised optometric assessment. The cost-effectiveness of the screening programme was highly sensitive to the perspective on costs (NHS or societal). In the base-case model, the NHS costs of visual impairment were estimated as £669. If annual societal costs were £8800, then screening might be considered cost-effective for a 40-year-old cohort with 1% OAG prevalence assuming a willingness to pay of £30,000 per quality-adjusted life-year. Of lesser importance were changes to estimates of attendance for sight tests, incidence of OAG, rate of progression and utility values for each stage of OAG severity. Cost-effectiveness was not particularly sensitive to the accuracy of screening tests within the ranges observed. However, a highly specific test is required to reduce large numbers of false-positive referrals. The findings that population screening is unlikely to be cost-effective are based on an economic model whose parameter estimates have considerable uncertainty, in particular, if rate of progression and/or costs of visual impairment are higher than estimated then screening could be cost-effective. Conclusions: While population screening is not cost-effective, the targeted screening of high-risk groups may be. Procedures for identifying those at risk, for quality assuring the programme, as well as adequate service provision for those screened positive would all be needed. Glaucoma detection can be improved by increasing attendance for eye examination, and improving the performance of current testing by either refining practice or adding in a technology-based first assessment, the latter being the more cost-effective option. This has implications for any future organisational changes in community eye-care services. Further research should aim to develop and provide quality data to populate the economic model, by conducting a feasibility study of interventions to improve detection, by obtaining further data on costs of blindness, risk of progression and health outcomes, and by conducting an RCT of interventions to improve the uptake of glaucoma testing. © Queen's Printer and Controller of HMSO 2007. All rights reserved.

Diagnostic accuracy and reproducibility of tendency oriented perimetry in glaucoma

PURPOSE. To evaluate the diagnostic capability of tendency oriented perimetry (TOP) in glaucoma. METHODS. A): The diagnostic accuracy of mean defect (MD), square-root of the loss variance (sLV), and number of pathologic points (NPP) was calculated in 295 normal and 414 glaucoma eyes (179 early, 112 moderate, and 123 advanced) examined with TOP. B): Threshold fluctuation (F) and its relationship with the loss variance (LV) was measured in 34 normal and 33 glaucoma eyes (mean MD=3 dB; SD=3.9) for TOP and for full-threshold perimetry (FT). C): Twenty-eight eyes with stable glaucoma (mean MD=9.5 dB; SD=7.2) were examined six times to quantify LV error. D): TOP and FT were tested with the simulation program PeriSim using different behavior models. RESULTS. A): The best diagnostic index in early glaucoma (MD

Recurrent vitreous occlusion of glaucoma drainage device tube in a patient with glaucoma in aphakia:A case report

Patients with spontaneous lens dislocation and glaucoma can be challenging to manage. We present a forty-six year old Caucasian lady who was referred with bilateral high intraocular pressure, and was subsequently diagnosed with glaucoma in association with lens dislocation and Marfan syndrome. Baerveldt glaucoma drainage device tubes were inserted in both eyes due to poor response to medical therapy. However, this was complicated by recurrent vitreous occlusion of both glaucoma drainage tubes requiring further multiple surgical interventions. There have not been any further recurrences of vitreous incarceration or posterior segment complications since, but the patient remains under close follow-up. © 2010 Ang et al; licensee BioMed Central Ltd.

Oral prednisone in guarded filtration procedures supplemented with antimetabolites

BACKGROUND AND OBJECTIVE: To evaluate whether a three-day course of oral prednisone perioperatively improves the surgical outcome of guarded filtering procedures supplemented with antifibrosis agents. DESIGN, MATERIALS AND METHODS: A prospective, randomized, double-masked, placebo-controlled, clinical trial was designed. Adult patients with non-inflammatory glaucoma undergoing a guarded filtration procedure supplemented with antimetabolite were enrolled. Patients received a three-day course of prednisone (50 mg BID) or placebo perioperatively. The main outcome measures were intraocular pressure (IOP) and number of antiglaucoma medications. Surgical success was defined before data collection according to two different criteria: 'success- I': IOP level = 15 mmHg with no more than one anti-glaucoma medication, and 'success-II': IOP reduction of at least 20% of baseline level with no more than one antiglaucoma medication. RESULTS: Thirty-five subjects were enrolled. Seventeen patients were treated with prednisone and eighteen with placebo. Mean follow-up was 9.2 months ± 6.2 months. The probability of success-I at 9 months was 63.0% in the study group and 65.6% in the control groups (p>0.05). The probability of success-II at 9 months was 60.2% in the study group and 55.0% in the control groups, (p>0.05). The difference in frequency of postoperative complications between groups was not statistically significant. The most common complication was choroidal detachment (n=2) in the prednisone-treated group and bleb leak (n=2) in the control group. CONCLUSION: The perioperative use of oral prednisone did not alter the surgical outcome of filtering procedures associated with antifibrosis agents in this population of glaucoma patients.

What is the best method for diagnosing glaucoma?

Glaucoma is characterized by a typical appearance of the optic disc and peripheral visual field loss. However, diagnosis may be challenging even for an experienced clinician due to wide variability among normal and glaucomatous eyes. Standard automated perimetry is routinely used to establish the diagnosis of glaucoma. However, there is evidence that substantial retinal ganglion cell damage may occur in glaucoma before visual field defects are seen. The introduction of newer imaging devices such as confocal scanning laser ophthalmoscopy, scanning laser polarimetry and optical coherence tomography for measuring structural changes in the optic nerve head and retinal nerve fiber layer seems promising for early detection of glaucoma. New functional tests may also help in the diagnosis. However, there is no evidence that a single measurement is superior to the others and a combination of tests may be needed for detecting early damage in glaucoma. © 2010 Expert Reviews Ltd.

Lifetime visual prognosis of patients with glaucoma

BACKGROUND: To investigate the visual outcome of glaucoma patients.

DESIGN: This is a retrospective study of case notes of patients who died while under follow up in a glaucoma clinic of a University Hospital in Scotland between 2006 and 2009.

PARTICIPANTS: Seventy-seven patients were identified.

METHODS: Data collected included type of glaucoma, coexisting pathology and best-corrected visual acuity in Snellen (converted to decimal values) for the first and final clinic visit. The final visual status was evaluated based on the best-corrected visual acuity of the better seeing eye at the last glaucoma clinic visit. Patients who had best-corrected visual acuity of less than Snellen decimal 0.5 were considered not to meet the standards for driving.

MAIN OUTCOME MEASURES: Snellen decimal best-corrected visual acuity, fulfilment of driving standards, and eligibility for partial sight and blind registration at the last clinic visit.

RESULTS: The mean ages at presentation and death were 71.8 ± 10.3 years and 82.2 ± 8.7 years respectively. The mean Snellen decimal best-corrected visual acuity of the better eye at presentation was 0.78, and at the final clinic visit was 0.61. At the final clinic visit, no patients were partial sight registrable, four (5.2%) were blind registrable, and 27 (35.1%) did not fulfil UK driving criteria. Glaucoma patients with other ocular pathologies were more likely to fail UK driving criteria at presentation (P = 0.02) and at last clinic visit (P = 0.03).

CONCLUSION: The majority of glaucoma patients maintained good visual function at the end of their lifetime.

Surgical technique:Complex glaucoma case requiring molteno drainage tube extension

A 42-year-old man has been under long-term follow-up since he was a child for congenital glaucoma and buphthalmos in both eyes. His left eye best corrected visual acuity (BCVA) was counting fingers, due to end-stage glaucoma. He was on maximal medical therapy with an intraocular pressure (IOP) maintained at mid to low twenties. His right eye, the only seeing eye, had a BCVA of 6/9. This eye had undergone multiple glaucoma laser and surgical procedures, including an initial first Molteno drainage device inserted superonasally that failed in April 2003 due to fibrotic membrane over the tube opening. As a result, he subsequently had a second Molteno drainage device inserted inferotemporally. To further maximize his vision he had an uncomplicated cataract extraction and intraocular lens implant in December 2004, after which he developed postoperative cystoid macular edema and corneal endothelial failure. He underwent a penetrating keratoplasty in the right eye thereafter in March 2007. After approximately a year, the second Molteno device developed drainage tube retraction, which was managed surgically to maintain optimum IOP in the right eye. His right eye vision to date is maintained at 6/12. © 2011 Mustafa and Azuara-Blanco.

The quality of reporting of diagnostic accuracy studies in glaucoma using the Heidelberg retina tomograph

PURPOSE. Scanning laser tomography with the Heidelberg retina tomograph (HRT; Heidelberg Engineering, Heidelberg, Germany) has been proposed as a useful diagnostic test for glaucoma. This study was conducted to evaluate the quality of reporting of published studies using the HRT for diagnosing glaucoma. METHODS. A validated Medline and hand search of English-language articles reporting on measures of diagnostic accuracy of the HRT for glaucoma was performed. Two reviewers selected and appraised the papers independently. The Standards for Reporting of Diagnostic Accuracy (STARD) checklist was used to evaluate the quality of each publication. RESULTS. A total of 29 articles were included. Interobserver rating agreement was observed in 83% of items (? = 0.76). The number of STARD items properly reported ranged from 5 to 18. Less than a third of studies (7/29) explicitly reported more than half of the STARD items. Descriptions of key aspects of the methodology were frequently missing. For example, the design of the study (prospective or retrospective) was reported in 6 of 29 studies, and details of participant sampling (e.g., consecutive or random selection) were described in 5 of 29 publications. The commonest description of diagnostic accuracy was sensitivity and specificity (25/29) followed by area under the ROC curve (13/29), with 9 of 29 publications reporting both. CONCLUSIONS. The quality of reporting of diagnostic accuracy tests for glaucoma with HRT is suboptimal. The STARD initiative may be a useful tool for appraising the strengths and weaknesses of diagnostic accuracy studies. Copyright © Association for Research in Vision and Ophthalmology.

Corneal biomechanical properties in primary open angle glaucoma and normal tension glaucoma

PURPOSE: To determine and compare the corneal biomechanical properties between eyes with primary open angle glaucoma (POAG) and eyes with normal tension glaucoma (NTG). PATIENTS AND METHODS: Prospective cross-sectional study. Consecutive eligible POAG and NTG patients attending the Glaucoma Clinic had assessment of their corneal biomechanical properties-corneal hysteresis (CH) and corneal resistance factor (CRF)-using the Ocular Response Analyzer by an observer masked to the diagnosis. Exclusion criteria included previous intraocular surgery, corneal pathology, inflammatory connective tissue disease, and refraction of 5-dimensional or over. If both eyes were eligible, then the right eye was used for analysis. The main outcome measures were corneal hysteresis and CRF measurements. Data analysis was performed using the t test and general linear model. RESULTS: Eighty-one patients (80 whites) were analyzed. Forty had NTG, whereas 41 had POAG. Thirty-five were females. There was a statistically significant difference in mean CH (NTG 9.6±1.3 mm Hg; POAG 9.0±1.4 mm Hg; P=0.01), but not in mean CRF (NTG 9.9±1.4; POAG 10.8±1.7; P=0.06). The highest recorded Goldmann applanation intraocular pressure (IOP) was statistically significantly associated with lower CH (P=0.01) and higher CRF (P=0.02). CONCLUSIONS: There was a small but statistically significant difference in the mean CH between POAG and NTG (CH was higher in NTG). The highest recorded Goldmann applanation IOP was also statistically significantly correlated with lower CH and higher CRF, suggesting that alterations to the corneal biomechanical properties may occur as a result of chronic raised IOP in POAG. © 2008 by Lippincott Williams & Wilkins.

Direct costs of glaucoma and severity of the disease:A multinational long term study of resource utilisation in Europe

Background: Resource utilisation and direct costs associated with glaucoma progression in Europe are unknown. As population progressively ages, the economic impact of the disease will increase. Methods: From a total of 1655 consecutive cases, the records of 194 patients were selected and stratified by disease severity. Record selection was based on diagnoses of primary open angle glaucoma, glaucoma suspect, ocular hypertension, or normal tension glaucoma; 5 years minimum follow up were required. Glaucoma severity was assessed using a six stage glaucoma staging system based on static threshold visual field parameters. Resource utilisation data were abstracted from the charts and unit costs were applied to estimate direct costs to the payer. Resource utilisation and estimated direct cost of treatment, per person year, were calculated. Results: A statistically significant increasing linear trend (p = 0.018) in direct cost as disease severity worsened was demonstrated. The direct cost of treatment increased by an estimated €86 for each incremental step ranging from €455 per person year for stage 0 to €969 per person year for stage 4 disease. Medication costs ranged from 42% to 56% of total direct cost for all stages of disease. Conclusions: These results demonstrate for the first time in Europe that resource utilisation and direct medical costs of glaucoma management increase with worsening disease severity. Based on these findings, managing glaucoma and effectively delaying disease progression would be expected to significantly reduce the economic burden of this disease. These data are relevant to general practitioners and healthcare administrators who have a direct influence on the distribution of resources.

Primary angle closure glaucoma:A descriptive study in Scottish Caucasians

Purpose: The aim of this study is to describe the ocular and demographic features of Caucasian patients newly presenting with primary angle closure glaucoma and the proportion of workload it represents at a tertiary university hospital glaucoma service. Methods: A retrospective case notes review was conducted for all Caucasian patients newly diagnosed with narrow angles, primary angle closure, acute primary angle closure and primary angle closure glaucoma that were seen over a period of 2 years. Demographic and ocular variables were compared and statistical analysis was carried out with the paired t -test and chi-squared test. Number of primary open angle closure glaucoma and acute angle closure cases were compared with total number of new referrals to the department, new patients diagnosed with glaucoma and population numbers for the North East of Scotland. Results: One hundred and four patients were analysed. Twenty-four (23.1%) had narrow angles, 30 (28.8%) had primary angle closure and 50 (48.1%) had primary angle closure glaucoma. Twelve (11.5%) presented with acute primary angle closure. There was no significant difference for gender, age, hypermetropia or visual acuity between groups. Primary angle closure glaucoma constituted 22.9% (50/128) of newly diagnosed glaucoma cases. Based on the 2001 Scotland census, the crude annual incidence of newly diagnosed primary angle closure glaucoma was estimated at 14.8 per 100000 and 3.6 per 100000 for acute primary angle closure in the over-45-year-old population. Conclusion: Our study confirms that primary angle closure glaucoma is uncommon in Caucasians, but not as rare as originally perceived as it makes up a fair proportion (22.9%) of glaucoma workload. © 2009 The Authors Journal Compilation © 2009 Royal Australian and New Zealand College of Ophthalmologists.