Publications by authors named "Rikkert van der Valk"

The aim of this study was to review the literature on predictive factors for postoperative visual acuity (VA) in surgery for idiopathic epiretinal membrane (ERM). A systematic review of the literature in the databases of PubMed and Embase was performed. The risk of bias was assessed based on predefined criteria and the results were summarized.

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Purpose: To systematically review the influence of the lag time between macula-off retinal detachment and surgical intervention on postoperative visual acuity as main outcome measure.

Methods: Systematic review and meta-analysis of articles published from 1995 to October 2013 of patients with macula-off retinal detachment and treated with scleral buckling or pars plana vitrectomy. Eligible data were pooled in a meta-analysis, analyzing the odds ratio between different durations of ≤ 3, ≤ 4, ≤ 7, and ≤ 10 days, comparing a final visual acuity of ≤ 0.

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Purpose: To compare the effect of corneal cross-linking (CXL) for keratoconus in various age groups and to investigate the influence of the topographic cone location on the outcome of CXL.

Methods: This cohort study included 95 patients (119 eyes) diagnosed as having progressive keratoconus who underwent epithelium-off standard protocol CXL from January 2010 through May 2012. For statistical analysis, patients were divided into three age groups: pediatric patients (< 18 years), adolescent patients (18 to 26 years), and adults (> 26 years).

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Purpose: To compare central corneal thickness (CCT) with and without using an eyelid speculum during corneal collagen crosslinking (CXL).

Setting: University Medical Center Utrecht, Utrecht, the Netherlands.

Design: Prospective nonrandomized comparative study.

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Purpose: To evaluate the 1-year results of corneal collagen crosslinking (CXL) in mild to moderate cases and advanced cases of progressive keratoconus.

Setting: Department of Ophthalmology, University Medical Center Utrecht, the Netherlands.

Design: Retrospective cohort study.

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The authors describe four children with progressive keratoconus treated by corneal crosslinking (CXL). The current CXL guidelines recommend treatment of patients 18 years and older. Nevertheless, keratoconus can rapidly progress in young teenagers.

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Objective: It is difficult to rank treatments according to their effect size when several treatments are available and not all treatments have been compared directly. The purpose of this study was to show a new statistical technique (network meta-analysis) to address this problem and to rank glaucoma drugs according to their intraocular pressure (IOP)-reducing effect.

Study Design And Setting: Network meta-analysis of randomized controlled trials was used to combine direct and indirect estimates of the effect of eight drugs and placebo from 28 randomized controlled trials in patients with primary open-angle glaucoma or ocular hypertension patients, 6,841 for the peak effect and 6,953 patients for the trough effect.

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Background: To compare the tolerability of commonly prescribed topical glaucoma medications by determining frequency and bother of side effects, patient satisfaction with their medication, and the chance of discontinuation of eye drops.

Methods: The tolerability of topical glaucoma medication was studied in glaucoma patients from nine hospitals. The frequency and severity of side effects was investigated together with patient satisfaction with the medication and the probability to change medication due to reported side effects.

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Purpose: To study intraocular pressure (IOP) reductions with timolol and latanoprost reached in clinical practice, taking into account data that are routinely collected by the ophthalmologist; to predict IOP reduction from these variables.

Methods: A cohort of patients with primary open-angle glaucoma (suspect) or ocular hypertension was recruited from nine Dutch centres. Mean absolute and relative IOP reduction was calculated in order to compare timolol to latanoprost.

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Purpose: To describe changes in glaucoma treatment and achieved IOP (intraocular pressure) over the period 1995-2002, 4 years before and 4 years after new glaucoma drugs had become available (January 1999).

Methods: An observational study was conducted in primary open-angle glaucoma (suspect), and ocular hypertension patients (n=1561) who had started medical treatment in 1995 or thereafter. The processes of starting, changing and intensifying medical treatment in general, and in patients with contraindications to beta-blockers before and after January 1999 were described.

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Objective: To estimate the intraocular pressure (IOP) reduction achieved by the most frequently prescribed glaucoma drugs and a placebo in a meta-analysis of randomized clinical trials.

Design: Meta-analysis of randomized clinical trials.

Participants: Twenty-seven articles reporting on 28 randomized clinical trials.

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Purpose: To study the trend in number of glaucoma surgeries, and the influence hereon of the introduction of new glaucoma medication, reimbursement of its costs, and the introduction of a treatment protocol.

Methods: Out of the Dutch Health Care Registration, all open angle glaucoma and ocular hypertension patients aged 20 years and older, who underwent glaucoma surgery were selected. Over the period 1995 until 2003 the trend in the number of monthly performed glaucoma surgeries was described by LOESS spline procedure.

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Background: Iron supplementation is recommended for children at high risk of anaemia, but its benefits may not outweigh the associated risk of malaria in areas of seasonal transmission. We investigated the effect on haemoglobin concentrations of intermittent administration of iron supplements and sulfadoxine-pyrimethamine in symptom-free children under intense health surveillance.

Methods: In a trial of two by two factorial design, 328 anaemic Kenyan children were randomly assigned either iron or placebo and sulfadoxine-pyrimethamine or placebo (82 to each group).

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