A 'chemical help' in middle-ear surgery? A systematic review on sodium 2-mercaptoethanesulfonate.

OBJECTIVE: Sodium 2-mercaptoethanesulfonate (Mesna) has been proposed as a chemical aid in any surgical procedure, including cholesteatoma surgery. This review investigated the benefits and safety of Mesna during surgical management of cholesteatoma and adhesive otitis media. METHOD: A systematic literature review was performed to identify clinical studies evaluating topical Mesna application during ear surgery (cholesteatoma or atelectasis). A qualitative analysis based on data extracted was conducted. RESULTS: From 27 articles, 5 retrospective studies were selected for a full analysis for a total of 607 patients (aged 5 to 72 years). Three studies evaluated cholesteatoma recidivism after Mesna application during cholesteatoma surgery, one study evaluated the surgical success rate of Mesna application for the treatment of atelectatic ears and adhesive otitis media, and one study evaluated potential ototoxicity of Mesna during cholesteatoma surgery. All the studies showed overall improvement in recurrence and residual cholesteatoma disease after Mesna application during surgery. Sensorineural hearing loss was not encountered after Mesna application. CONCLUSION: Mesna application in cholesteatoma surgery could represent a valid and safe support tool during surgical treatment carried out both with microscopy and endoscopy. More studies are required to confirm these promising results.

A systematic review of presacral extramedullary haematopoiesis: a diagnosis to be considered for presacral masses.

AIM: Presacral masses are uncommon and have malignant potential; treatment typically includes surgical excision. However, there are conditions such as extramedullary haematopoiesis (EMH) which are benign. The present study aimed to summarize the presentation of presacral EMH in our institution, to review the literature and to offer management strategies for this rare condition. METHOD: The literature was searched for articles related to presacral EMH, and case reports were collected from articles meeting the inclusion criteria. We collected data on patient demographics, diagnostic investigation, management and the results of treatment. RESULTS: Thirty-nine patients were included in the systematic review. Initial imaging included computed tomography (CT), magnetic resonance imaging (MRI) or ultrasound (US) suggestive of EMH. Some patients then underwent a technetium scan (n = 7, 18%), biopsy of the presacral lesion (n = 27, 69%) or excision of the entire mass (n = 3, 8%). All patients who underwent technetium scan were confirmed to have EMH, demonstrating enhancement similar to bone marrow. Patients who underwent technetium scan and presacral mass biopsy had concordant results confirming presacral EMH (n = 5, 13%). Data on management were available for 35/39 (90%) with most patients followed by clinical observation (n = 20, 51%). Symptomatic patients were treated with radiotherapy (15%), surgical excision (15%) or hydroxyurea (5%) and blood transfusions (10%). Most (81%, n = 17/21) patients whose outcome was reported remained asymptomatic or experienced pain relief. CONCLUSION: Although uncommon, EMH should be considered in the differential diagnosis of a presacral mass. Presacral EMH is a benign condition that can be suspected on CT or MRI and confirmed with technetium scan. Patients may not necessarily need to undergo biopsy to confirm haematopoietic elements. Unlike other presacral masses, patients diagnosed with presacral EMH can be managed by observation. If symptomatic, radiotherapy or surgical excision may be offered.

Can we safely recommend gestational weight gain below the 2009 guidelines in obese women? A systematic review and meta-analysis.

A systematic review was conducted to determine the risk of adverse pregnancy outcomes with gestational weight gain (GWG) below the 2009 Institute of Medicine guidelines compared with within the guidelines in obese women. MEDLINE, Embase, Cochrane Register, CINHAL and Web of Science were searched from 1 January 2009 to 31 July 2014. Quality was assessed using a modified Newcastle-Ottawa scale. Three primary outcomes were included: preterm birth, small for gestational age (SGA) and large for gestational age (LGA). Eighteen cohort studies were included. GWG below the guidelines had higher odds of preterm birth (adjusted odds ratio [AOR] 1.46; 95% confidence interval [CI] 1.07-2.00) and SGA (AOR 1.24; 95% CI 1.13-1.36) and lower odds of LGA (AOR 0.77; 95% CI 0.73-0.81) than GWG within the guidelines. Across the three obesity classes, the odds of SGA and LGA did not show any notable gradient and remained unexplored for preterm birth. Decreased odds were noted for macrosomia (AOR 0.64; 95% CI 0.54-0.77), gestational hypertension (AOR, 0.70; 95% CI 0.53-0.93), pre-eclampsia (AOR 0.90; 95% CI 0.82-0.99) and caesarean (AOR 0.87; 95% CI 0.82-0.92). GWG below the guidelines cannot be routinely recommended but might occasionally be individualized for certain women, with caution, taking into account other known risk factors.

Spatial distribution of contextual interactions in primary visual cortex and in visual perception.

To examine the role of primary visual cortex in visuospatial integration, we studied the spatial arrangement of contextual interactions in the response properties of neurons in primary visual cortex of alert monkeys and in human perception. We found a spatial segregation of opposing contextual interactions. At the level of cortical neurons, excitatory interactions were located along the ends of receptive fields, while inhibitory interactions were strongest along the orthogonal axis. Parallel psychophysical studies in human observers showed opposing contextual interactions surrounding a target line with a similar spatial distribution. The results suggest that V1 neurons can participate in multiple perceptual processes via spatially segregated and functionally distinct components of their receptive fields.

Interactions between attention, context and learning in primary visual cortex.

Attention in early visual processing engages the higher order, context dependent properties of neurons. Even at the earliest stages of visual cortical processing neurons play a role in intermediate level vision - contour integration and surface segmentation. The contextual influences mediating this process may be derived from long range connections within primary visual cortex (V1). These influences are subject to perceptual learning, and are strongly modulated by visuospatial attention, which is itself a learning dependent process. The attentional influences may involve interactions between feedback and horizontal connections in V1. V1 is therefore a dynamic and active processor, subject to top-down influences.

Surgically induced astigmatism after photorefractive keratectomy with the excimer laser.

PURPOSE: To evaluate retrospectively the effect of spherical excimer laser photorefractive keratectomy (PRK) on astigmatism. METHODS: Four hundred seventy consecutive eyes of patients who had PRK for the treatment of myopia without astigmatic keratotomy, PRK reoperation, or other surgical procedures were evaluated in a retrospective clinical study. PRK was performed using the Summit Apex excimer laser with attempted corrections from 1 to 7 diopters (D) of myopia. Preoperative and postoperative astigmatism was determined by manifest refraction refined with a 0.25-D Jackson cross cylinder and evaluated with vector analysis. RESULTS: Eighty-five ( 18%) eyes continued to have a spherical refraction after PRK, 53 (11%) eyes had the same preoperative astigmatism, and 332 (71%) eyes had a change in magnitude of astigmatism > or =0.25 D after spherical PRK. The absolute change in astigmatism magnitude irrespective of axis was +0.4 +/- 0.4 (standard deviation) D at 6 months after PRK. Eyes with change in astigmatism power tended to have higher preoperative myopia and higher preoperative astigmatism. Vector analysis revealed surgically induced astigmatism was 0.68 +/- 0.50 D (range, 0-3.25 D) at 1 month and 0.56 +/- 0.47 D (range, 0-3.1 D) at 12 months after spherical PRK. CONCLUSION: Spherical excimer laser PRK is associated with significant surgically induced astigmatism that is likely related to decentration of the ablation, excimer laser beam irregularities, and variations in wound healing across the ablated zone. Surgically induced astigmatism will complicate attempts to correct astigmatism simultaneously at the time of PRK and suggest that such attempts are likely to be problematic for lower levels of astigmatism.

One-year results of PRK in low and moderate myopia: fewer than 0.5% of eyes lose two or more lines of vision.

PURPOSE: To retrospectively evaluate the results of myopic photorefractive keratectomy (PRK) for different levels of intended correction, including analysis of loss of best spectacle-corrected visual acuity. METHODS: Four hundred seventy-five consecutive eyes with 1 year of follow-up that had PRK for the correction of 1-7 diopters (D) of myopia by using the Summit SVS Apex excimer laser. Three hundred forty-eight eyes were examined at 1 year. This study was confined to the 236 eyes with 1 year of follow-up that had PRK without astigmatic keratotomy. Eyes also were analyzed according to the range of attempted correction (0-3 D, low; 3.1-6D, moderate; and > or =6.1 D, high moderate). Manifest refraction, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), surface regularity index (SRI), and surface asymmetry index (SAI) were evaluated for each group. RESULTS: One year after PRK, 91% of all eyes were within 1 diopter and 73% of eyes were within 0.5 diopter of emmetropia. Uncorrected visual acuity was 20/25 or better in 79% and 20/40 or better in 96% of eyes. Two lines of BSCVA were lost in only 0.4% of eyes (one of 236). No eye lost >2 lines of BSCVA, and 30% gained one line. Mean SRI and SAI were increased as compared with preoperative values, but were within the normal range for our patient population (ranges, 0.2-1.0 and 0.1-0.7, respectively). UCVA, BSCVA, and predictability decreased, whereas SAI and SRI increased, with increasing attempted correction. CONCLUSION: PRK effectively reduced myopia in all eyes with 12 months' follow-up. Predictability tended to decrease with increasing attempted correction, even for low to moderate myopia. PRK may induce mild surface asymmetry and irregularity, and these alterations tend to increase with higher attempted correction. Fewer than 0.5% of eyes lost > or =2 lines of best-corrected visual acuity.

Arcuate transverse keratotomy remains a useful adjunct to correct astigmatism in conjunction with photorefractive keratectomy.

PURPOSE: To retrospectively evaluate the effectiveness of paired, arcuate transverse keratotomy (Arc-T) performed prior to or after photorefractive keratectomy (PRK) to correct low to moderate amounts of natural or laser-induced astigmatism. METHODS: Spherical PRK was performed in 730 eyes for myopia of -1.00 to -7.00 D. PRK with arcuate transverse keratotomy was performed in 150 of these eyes; we studied 123 eyes that did not have PRK enhancement. Arc-T was performed prior to PRK in all 37 study eyes with astigmatism of 1.50 D or more at the preoperative examination. Arc-T keratotomy was performed after PRK in 86 study eyes for residual astigmatism of +0.75 D or more and uncorrected visual acuity of 20/30 or worse. RESULTS: Arc-T before PRK group: PRK was performed at a mean 1.0 +/- 1.5 months after Arc-T. Mean astigmatism decreased from +2.40 +/- 0.6 D (range, 1.00 to 4.00 D) before Arc-T to 0.60 +/- 0.60 D (range, 0 to 2.25 D) after Arc-T (P < .0001). Net change in astigmatism was 1.80 +/- 0.60 D (range, 0.80 to 2.80 D) and mean reduction was 75%. Spherical equivalent refraction changed from -4.10 +/- 1.90 D (range, -0.25 to -8.10 D) to -4.40 +/- 1.80 D after Arc-T (P = .002). Mean change in spherical equivalent refraction after Arc-T was -0.30 +/- 0.50 D (range, -1.10 to +0.40 D). Arc-T after PRK group: Arc-T was performed at a mean 3.5 +/- 1.9 months after PRK. Six months after Arc-T, astigmatism was decreased from +1.50 +/- 0.60 D to 0.40 +/- 0.40 D (P = .04). Net change in astigmatism at 6 months was 1.10 +/- 0.60 D and mean reduction was 74%. Vector change in astigmatism magnitude was 1.30 +/- 0.60 D (range, 0 to 4.00 D) at 6 months and vector change in astigmatism axis was 65 degrees +/- 68 degrees. Spherical equivalent refraction did not change when Arc-T was performed after PRK for eyes with low astigmatism (P = .4). Arc-T retreatment was performed in 6 of 37 (16%) eyes that had Arc-T before PRK and 18 of 86 (21%) eyes that had Arc-T after PRK (P = .12). CONCLUSION: Arcuate transverse keratotomy performed prior to PRK for high astigmatism or after PRK for lower levels of residual astigmatism effectively improved visual outcome. Coupling was less predictable for high levels of astigmatism correction with Arc-T.

Epithelial scrape for photorefractive keratectomy overcorrection associated with induced regression.

PURPOSE: To study the effect of combined corneal epithelial scrape and contact lens wear treatment on regression in eyes with symptomatic overcorrection after photorefractive keratectomy (PRK) or PRK retreatment. METHODS: Fifteen eyes had corneal epithelial scrape with a scalpel followed by soft contact lens wear for approximately 1 month. Eight of the eyes were treated 3-4 months after the laser procedure, and seven eyes were treated >4 months after laser treatment. Fifteen eyes that had the same level of PRK correction and monitored during the same interval after PRK were used as matched control eyes. RESULTS: Epithelial scrape was performed for mean spherical equivalent (SE) of +1.1+/-0.4 diopters (D) (range, +0.50 to +1.75 D) at mean 6.1+/-3.2 months after PRK or PRK retreatment. The SE in these eyes was +0.5+/-0.6 D (range, -0.25 to +1.25 D) 3 months after epithelial scrape and +0.4+/-0.5 D (range, -0.75 to +1.25 D) 6 months after scrape. The change in scraped eyes at 3 and 6 months compared to before scrape was statistically significant (p = 0.001 and p = 0.001, respectively). The change in mean SE at 6 months after scrape (-0.7+/-0.5 D) was significantly different than the change noted in matched control eyes that were not scraped (-0.1+/-0.2 D) over the same interval after the PRK or PRK retreatment procedure. The change in SE at 6 months after epithelial scrape was greater for the eyes scraped 4 months or less (mean, 3.6+/-0.5 months) after PRK (-0.9+/-0.3 D) than eyes scraped >4 months (9.0+/-2.6 months) after PRK (-0.4+/-0.5 D). This difference approached statistical significance (p = 0.06). CONCLUSIONS: Epithelial scrape and soft contact lens treatment for symptomatic overcorrection after PRK may induce regression and is more likely to be effective when performed <4 months after the primary PRK or PRK retreatment procedure.

Dynamics of spatial summation in primary visual cortex of alert monkeys.

One of the fundamental tasks of the visual cortex is to integrate input from different parts of the retina, parsing an image into contours and surfaces, and then assembling these features into coherent representations of objects. To examine the role of the primary visual cortex in the integration of visual information, we measured the response properties of neurons under different stimulus conditions. Surprisingly, we found that even the most conventional measures of receptive field (RF) size were not fixed, but could vary depending on stimulus contrast and foreground-background relationships. On average, the length of the excitatory RF was 4-fold greater for a low-contrast stimulus than for a stimulus at high contrast. Embedding a high-contrast stimulus in a textured background tended to suppress neuronal responses and produced an enlargement in RF size similar to that observed by decreasing the contrast of an isolated stimulus. The results show that RF dimensions are regulated in a dynamic manner that depends both on local stimulus characteristics, such as contrast, and on global relationships between a stimulus and its surroundings.

Binocular function and patient satisfaction after monovision induced by myopic photorefractive keratectomy.

PURPOSE: To measure binocular function and patient satisfaction with monovision induced by photorefractive keratectomy (PRK) in myopic presbyopic patients. SETTING: Refractive Department, Cleveland Clinic, Cleveland, Ohio, USA. METHODS: This study comprised 21 myopic presbyopic patients with monovision induced by PRK. Sixteen emmetropic patients who had PRK served as a control group. Monovision was induced by undercorrecting the nondominant eye by 1.25 diopters for near vision and correcting the dominant eye with emmetropia for distance vision. Monocular and binocular uncorrected Snellen visual acuities at 20 feet and 13 inches, manifest refraction, ocular dominance, stereopsis at 20 feet and 13 inches, monocular and binocular contrast sensitivities, Worth-4-Dot test at 20 feet and 1/3 of a meter, and fusional convergence amplitudes were examined in each patient. RESULTS: In the monovision group at near and distance, 20 patients (95.3%) had binocular visual acuity of 20/25 or better. No patient in the monovision group used reading glasses postoperatively; 4 of 16 patients (25.0%) in the control group used such glasses. All patients maintained binocular fusion and stereo acuity ranging from 40 to 800 seconds of arc. Mean patient satisfaction was 86% (range 40% to 100%). In the control group, 12 patients (75.0%) had binocular distance visual acuity of 20/25 or better and 11 (68.8%) had binocular near visual acuity of 20/25 or better. CONCLUSION: Monovision PRK patients had better near vision than control PRK patients, with minimal compromise in stereo acuity and overall high patient satisfaction.

Epithelial removal with the excimer laser (laser-scrape) in photorefractive keratectomy retreatment.

OBJECTIVES: To retrospectively evaluate refractive and topographic outcomes after excimer laser photorefractive keratectomy (PRK) retreatment using the laser-scrape technique for epithelial removal. DESIGN: Retrospective clinical study. PARTICIPANTS: Thirty eyes of patients who had PRK retreatment for undercorrection after primary PRK were examined. INTERVENTION: The PRK retreatment was performed using a laser-scrape technique in which the excimer laser was used to remove the majority of the epithelium overlying the anterior stromal surface before additional PRK ablation. MAIN OUTCOME MEASURES: Uncorrected visual acuity, best-corrected visual acuity (BCVA), surface regularity index (SRI), and surface asymmetry index were measured. RESULTS: Primary PRK was performed for myopia of -5.1 +/- 1.7 diopters (range, -1.1 to -7.5 diopters). Mean spherical equivalent (SE) was -1.3 +/- 0.4 diopters (range, -0.6 to -2.0 diopters) before retreatment. Mean SE 6 months after retreatment decreased to +0.1 +/- 0.4 diopter (range, +1.25 to -0.75 diopters; P < 0.0001). Four eyes (15%) were more than +0.5 diopter overcorrected at 6 months. Ninety-six percent of eyes achieved mean SE within +/- 1 diopter and 77% within +/- 0.5 diopter of emmetropia after retreatment. Visual acuity improved significantly 6 months after reablation (P < 0.0001) with 100% 20/40 or better and 73% 20/25 or better without correction. Final BCVA also improved compared with before retreatment (P = 0.02). Twelve eyes gained 1 line of BCVA and no eye lost more than 1 line of BCVA. The SRI before retreatment was 0.6 +/- 0.3 (range, 0.0-0.9) and remained the same 0.6 +/- 0.2 (range, 0.1-1.0; P = 0.8), 6 months after retreatment. CONCLUSION: Excimer laser PRK retreatment using the laser-scrape technique for epithelial removal is an accurate and safe procedure for treating undercorrection of eyes after PRK for low-to-moderate myopia.

Transepithelial photorefractive keratectomy for treatment of thin flaps or caps after complicated laser in situ keratomileusis.

PURPOSE: To report transepithelial photorefractive keratectomy treatment of corneal irregularities produced during laser in situ keratomileusis (LASIK) in which there is a thin flap or cap associated with central corneal scarring or epithelial ingrowth that threatens vision. METHODS: Case reports. The thickness of the abnormal corneal flap or cap and associated scarring or epithelial ingrowth is estimated at the slit lamp or measured with an optical pachymeter. If residual myopia is sufficiently high to allow complete ablation of the flap or cap in the central cornea, a transepithelial photorefractive keratectomy is performed in which the epithelium is completely ablated with the excimer laser in phototherapeutic keratectomy mode; residual myopia is corrected using photorefractive keratectomy. RESULTS: This method was used successfully in two eyes of two patients in which a thin cap was associated with a transverse cut through the central cornea or a donut-shaped flap associated with epithelial ingrowth in the central cornea. In both cases, the abnormal cap or flap was ablated, central corneal clarity restored, and visual function improved. CONCLUSION: Transepithelial photorefractive keratectomy may be effective in treating central corneal thin cap or flap abnormalities associated with LASIK.

Photorefractive keratectomy using the summit SVS Apex laser with or without astigmatic keratotomy.

PURPOSE: The purpose of this study was to evaluate the results of myopic photorefractive keratectomy (PRK) with or without astigmatic keratotomy (AK) for different levels of intended correction by using the SVS Apex laser. METHODS: This is a retrospective cohort study of 226 eyes that had PRK for myopia ranging from -1.0 to -7.6 diopters and 6 months of follow-up. In addition, 64 of these eyes had AK for naturally occurring or laser-induced astigmatism. Uncorrected visual acuity, spectacle-corrected visual acuity, and corneal topography with quantitative descriptors of surface regularity (SRI) and surface asymmetry (SAI) were used to monitor the results of PRK with or without AK. RESULTS: At 6 months, 95.6% eyes had an uncorrected visual acuity of 20/40 or better, 90% eyes were within +/-1.0 diopter of emmetropia, and 3.1% eyes lost two lines of best-corrected vision. No eyes lost more than two lines of best-corrected vision. Mean refractive astigmatism was reduced, but mean SAI and SRI were increased, 6 months after PRK. Uncorrected vision, best-corrected vision, and predictability decreased, whereas SAI and SRI increased, with increasing attempted correction. CONCLUSION: PRK, with or without AK, effectively reduced myopia in all eyes by 6 months after surgery. Predictability tended to decrease with increasing attempted correction, even for eyes with relatively low to moderate myopia. PRK may induce surface asymmetry and irregularity at 6 months, and these alterations tend to be greater as the attempted correction increases.

Bioremediation of crude oil contamination with Acinetobacter sp. A3.

Acinetobacter sp. A3 is able to extensively degrade Bombay High Crude Oil (BHCO) and utilize it as the sole source of carbon. A total degradation of 70% BHCO was noted by the end of 120 h of growth of Acinetobacter sp. A3 under shake flask condition, 60% of which was due to biodegradation. In crude oil-contaminated soil (5%) amended with Acinetobacter sp. A3, there was both an increase in colony-forming units (CFU) and crude oil degradation. This is in contrast to a decrease in CFU of the indigenous microorganisms and lower degradation in unamended soil within the same 30-day period. Also, Acinetobacter sp. A3-treated soil permitted better germination of Mung beans (Phaseolus aureus) and growth as evidenced by better length and weight of the plants and chlorophyll content of its leaves, which was attributed to the reduction in phytotoxicity of the crude oil owing to its degradation. This crude oil degradative capability of Acinetobacter sp. A3 could be exploited for bioremediation purposes.

Perceptual learning of spatial localization: specificity for orientation, position, and context.

Discrimination of simple visual attributes can improve significantly with practice. We have trained human observers to perform peripherally presented tasks involving the localization of short line segments and examined the specificity of the learning for the visual location, orientation, and geometric arrangement of the trained stimulus. Several weeks of training resulted in dramatic threshold reductions. The learning was specific for the orientation and location of the trained stimulus, indicating the involvement of the earliest cortical stages in the visual pathway where the orientation and location of stimuli are mapped with highest resolution. Furthermore, improvement was also specific for both the configuration of the trained stimulus and the attribute of the stimulus that was under scrutiny during training. This degree of specificity suggests that the learning cannot be achieved by cortical recruitment alone, as proposed in current models, but is likely to involve a refinement of lateral interactions within the cortex and possibly a gating of lower level changes by attentional mechanisms.

Spatial integration and cortical dynamics.

Cells in adult primary visual cortex are capable of integrating information over much larger portions of the visual field than was originally thought. Moreover, their receptive field properties can be altered by the context within which local features are presented and by changes in visual experience. The substrate for both spatial integration and cortical plasticity is likely to be found in a plexus of long-range horizontal connections, formed by cortical pyramidal cells, which link cells within each cortical area over distances of 6-8 mm. The relationship between horizontal connections and cortical functional architecture suggests a role in visual segmentation and spatial integration. The distribution of lateral interactions within striate cortex was visualized with optical recording, and their functional consequences were explored by using comparable stimuli in human psychophysical experiments and in recordings from alert monkeys. They may represent the substrate for perceptual phenomena such as illusory contours, surface fill-in, and contour saliency. The dynamic nature of receptive field properties and cortical architecture has been seen over time scales ranging from seconds to months. One can induce a remapping of the topography of visual cortex by making focal binocular retinal lesions. Shorter-term plasticity of cortical receptive fields was observed following brief periods of visual stimulation. The mechanisms involved entailed, for the short-term changes, altering the effectiveness of existing cortical connections, and for the long-term changes, sprouting of axon collaterals and synaptogenesis. The mutability of cortical function implies a continual process of calibration and normalization of the perception of visual attributes that is dependent on sensory experience throughout adulthood and might further represent the mechanism of perceptual learning.