Prevention of post-dural puncture headache in parturients: a systematic review and meta-analysis.

Post-dural puncture headaches (PDPHs) present an important clinical problem. We assessed methods to decrease accidental dural punctures (ADPs) and interventions to reduce PDPH following ADP. Multiple electronic databases were searched for randomised clinical trials (RCTs) of parturients having labour epidurals, in which the studied intervention could plausibly affect ADP or PDPH, and the incidence of at least one of these was recorded. Forty RCTs (n = 11,536 epidural insertions) were included, studying combined spinal-epidurals (CSEs), loss of resistance medium, prophylactic epidural blood patches, needle bevel orientation, ultrasound-guided insertion, epidural morphine, Special Sprotte needles, acoustic-guided insertion, administration of cosyntropin, and continuous spinal analgesia. The RCTs for CSE, loss of resistance medium, and prophylactic epidural blood patches were meta-analysed. Five methods reduced PDPH: prophylactic epidural blood patch {four trials, median quality score = 2, risk difference = -0.48 [95% confidence interval (CI): -0.88 to -0.086]}, lateral positioning of the epidural needle bevel upon insertion (one trial, quality score = 1), Special Sprotte needles [one trial, quality score = 5, risk difference = -0.44 (95% CI: -0.67 to -0.21)], epidural morphine [one trial, quality score = 4, risk difference = -0.36 (95% CI -0.59 to -0.13)], and cosyntropin [one trial, quality score = 5, risk difference = -0.36 (95% CI -0.55 to -0.16)]. Several methods potentially reduce PDPH. Special Sprotte needles, epidural morphine, and cosyntropin are thus far each supported by a single, albeit good quality trial. Prophylactic blood patches are supported by three trials, but these had flawed methodology. Mostly, trials were of limited quality, and further well-conducted, large studies are needed.

Calculating the error in refractive error.

AIMS AND PURPOSE: To demonstrate a quick way of calculating the optical difference between two refractions using vector analysis, and to express this as a score for examination purposes. METHODS: An existing formula is applied, converted to a defocus equivalent, and then converted to a score. The formula is set out in an Excel spreadsheet. RESULTS: The spreadsheet enabled rapid assessment of the difference between two refractive errors. Examples are demonstrated. CONCLUSION: The spreadsheet was successful in enabling a comparison of any two refractions, expressing the difference either as a correcting (third) refraction, a defocus equivalent or a one-figure score.

Effects of conventional argon panretinal laser photocoagulation on retinal nerve fibre layer and driving visual fields in diabetic retinopathy.

AIMS: To determine the effects of argon green panretinal laser photocoagulation on retinal nerve fibre layer thickness, threshold visual fields, and Estermann full-binocular visual fields over time in diabetic retinopathy. METHOD: Prospective, pilot clinical study. Time-domain optical coherence tomography (TD-OCT) of the optic nerve head and 24-2 SITA-Fast Humphrey/Estermann visual fields (HVF, EVFs) recorded at baseline, 10 weeks, and 6 months post laser. Quantitative field analysis of central 10 degrees, 24 degrees, and binocular visual fields. RESULTS: A total of 10 eye samples were subjected to uncomplicated multiple-session 100 ms panretinal laser using 2000 burns, 300-microm spot, and mean power of 136 mW (SD+/-39.3). TD-OCT detected and quantified an increase in mean retinal nerve fibre layer thickness at 10 weeks (+8 microm; P<0.05) and progressive thinning at 6 months (-4 microm; P<0.05) compared with baseline. Mean threshold sensitivities, and 10 degrees and 24 degrees HVF improved at both time points in the majority (9 of 10 and 8 of 10) of patients. EVFs showed no significant change with treatment. CONCLUSIONS: This pilot study shows that conventional argon laser panretinal photocoagulation may increase the retinal nerve fibre layer thickness in the short term, presumably related to laser-induced axonal injury, with progressive thinning of nerve fibre layer over the long term. The 10 degrees and 24 degrees visual fields improved significantly after laser with no adverse effects on the UK standard driving fields.

In vivo fibreoptic confocal imaging (FOCI) of the human ocular surface.

Recent developments in the miniaturization of confocal imaging technology have resulted in the development of a hand-held confocal microscope probe. There are many structures of interest in the human eye that are within reach of a fluorescence-mode confocal microscope; this study assessed the feasibility of in vivo human ocular imaging. Safety analysis was undertaken to ensure that the laser light applied to the ocular surface structures constituted no threat to patient safety. A fibreoptic confocal imaging (FOCI) probe using an illumination wavelength of 488 nm was applied to the ocular surface of four volunteers after topical administration of sodium fluorescein. Stabilization of the probe on the ocular surface was difficult, but movement artefacts could be minimized to a satisfactory level in most subjects by a variety of procedures. High-quality images of conjunctival epithelial and goblet cells, lamina propria structures, accessory lacrimal glands, lacrimal ducts and superficial sclera were obtained. Lateral resolution was 1-1.5 microm and axial resolution was approximately 30 microm; individual erythrocytes could be seen in conjunctival vessels. The rete ridges and intervening epithelial components, including the probable location of corneal limbal stem cells, could be viewed, although it was not possible to distinguish cell subgroups. The study showed that fluorescence-mode imaging of the ocular surface is a viable and promising tool for assessment of diseases and processes involving superficial ocular structures. Refinement of equipment and techniques, particularly probe stabilization, is necessary to realize fully the potential of FOCI for ocular use.