Osmia lignaria (Hymenoptera: Megachilidae) increase pollination of Washington sweet cherry and pear crops.

Apis mellifera Linnaeus (Hymenoptera: Apis), honey bees, are the most widely used managed crop pollinators. However, their high rental cost and uncertain availability for North American orchard crops have motivated growers to explore alternative pollination options. We examined whether adding solitary, spring-flying Osmia lignaria Say (Hymenoptera: Megachilidae), blue orchard bees, as co-pollinators with A. mellifera in Washington sweet cherry and pear orchards enhances fruit set and yield compared to the use of A. mellifera alone. We added managed O. lignaria to orchard sites where A. mellifera hives were already present. Fruit set, fruit yield, and O. lignaria reproduction at O. lignaria-supplemented sites were compared to nearby, paired sites pollinated only by A. mellifera (3 paired cherry and 3 paired pear sites). For both crops, the addition of O. lignaria significantly increased fruit set but did not yield at harvest. Microscopic inspection of pollen grains from O. lignaria nest cell provisions confirmed that O. lignaria primarily visited orchard flowers. Mean retention of O. lignaria in cherry orchards was slightly higher (65%) than O. lignaria retention reported in other orchard crops (30%-60%). However, retention in pear orchards was much lower (≤20%). These results show that supplementing hives with O. lignaria in Washington spring orchard crops can increase overall pollination, but that trees fail to bear developing fruit to maturity. The strategy of using co-pollinators, O. lignaria and A. mellifera, in US orchards may act as "pollination insurance" when A. mellifera hives are in low supply or when the weather is not amenable for A. mellifera flight during the bloom period.

More than mesolectic: Characterizing the nutritional niche of Osmia cornifrons.

Characterizing the nutritional needs of wild bee species is an essential step to better understanding bee biology and providing suitable supplemental forage for at-risk species. Here, we aim to characterize the nutritional needs of a model solitary bee species, Osmia cornifrons (Radoszkowski), by using dietary protein-to-lipid ratio (P:L ratio) as a proxy for nutritional niche and niche breadth. We first identified the mean target P:L ratio (~3.02:1) and P:L collection range (0.75-6.26:1) from pollen provisions collected across a variety of sites and time points. We then investigated the P:L tolerance range of larvae by rearing bees in vitro on a variety of diets. Multifloral and single-source pollen diets with P:L ratios within the range of surveyed provisions did not always support larval development, indicating that other dietary components such as plant secondary compounds and micronutrients must also be considered in bee nutritional experiments. Finally, we used pollen metabarcoding to identify pollen from whole larval provisions to understand how much pollen bees used from plants outside of their host plant families to meet their nutritional needs, as well as pollen from individual forager bouts, to observe if bees maintained strict floral constancy or visited multiple plant genera per foraging bout. Whole larval provision surveys revealed a surprising range of host plant pollen use, ranging from ~5% to 70% of host plant pollen per provision. Samples from individual foraging trips contained pollen from multiple genera, suggesting that bees are using some form of foraging decision making. Overall, these results suggest that O. cornifrons have a wide nutritional niche breadth, but while pollen P:L ratio tolerance is broad, a tolerable P:L ratio alone is not enough to create a quality diet for O. cornifrons, and the plant species that make up these diets must also be carefully considered.

MeCP2 deficiency impairs motor cortical circuit flexibility associated with motor learning.

Loss of function mutations in the X-linked gene encoding methyl-CpG binding protein 2 (MECP2) cause Rett syndrome (RTT), a postnatal neurological disorder. The loss of motor function is an important clinical feature of RTT that manifests early during the course of the disease. RTT mouse models with mutations in the murine orthologous Mecp2 gene replicate many human phenotypes, including progressive motor impairments. However, relatively little is known about the changes in circuit function during the progression of motor deficit in this model. As the motor cortex is the key node in the motor system for the control of voluntary movement, we measured firing activity in populations of motor cortical neurons during locomotion on a motorized wheel-treadmill. Different populations of neurons intermingled in the motor cortex signal different aspects of the locomotor state of the animal. The proportion of running selective neurons whose activity positively correlates with locomotion speed gradually decreases with weekly training in wild-type mice, but not in Mecp2-null mice. The fraction of rest-selective neurons whose activity negatively correlates with locomotion speed does not change with training in wild-type mice, but is higher and increases with the progression of locomotion deficit in mutant mice. The synchronization of population activity that occurs in WT mice with training did not occur in Mecp2-null mice, a phenotype most clear during locomotion and observable across all functional cell types. Our results could represent circuit-level biomarkers for motor regression in Rett syndrome.

CropPol: A dynamic, open and global database on crop pollination.

Seventy five percent of the world's food crops benefit from insect pollination. Hence, there has been increased interest in how global change drivers impact this critical ecosystem service. Because standardized data on crop pollination are rarely available, we are limited in our capacity to understand the variation in pollination benefits to crop yield, as well as to anticipate changes in this service, develop predictions, and inform management actions. Here, we present CropPol, a dynamic, open, and global database on crop pollination. It contains measurements recorded from 202 crop studies, covering 3,394 field observations, 2,552 yield measurements (i.e., berry mass, number of fruits, and fruit density [kg/ha], among others), and 47,752 insect records from 48 commercial crops distributed around the globe. CropPol comprises 32 of the 87 leading global crops and commodities that are pollinator dependent. Malus domestica is the most represented crop (32 studies), followed by Brassica napus (22 studies), Vaccinium corymbosum (13 studies), and Citrullus lanatus (12 studies). The most abundant pollinator guilds recorded are honey bees (34.22% counts), bumblebees (19.19%), flies other than Syrphidae and Bombyliidae (13.18%), other wild bees (13.13%), beetles (10.97%), Syrphidae (4.87%), and Bombyliidae (0.05%). Locations comprise 34 countries distributed among Europe (76 studies), North America (60), Latin America and the Caribbean (29), Asia (20), Oceania (10), and Africa (7). Sampling spans three decades and is concentrated on 2001-2005 (21 studies), 2006-2010 (40), 2011-2015 (88), and 2016-2020 (50). This is the most comprehensive open global data set on measurements of crop flower visitors, crop pollinators and pollination to date, and we encourage researchers to add more datasets to this database in the future. This data set is released for non-commercial use only. Credits should be given to this paper (i.e., proper citation), and the products generated with this database should be shared under the same license terms (CC BY-NC-SA).

Adult body size measurement redundancies in Osmia lignaria and Megachile rotundata (Hymenoptera: Megachilidae).

Metrics to assess relative adult bee body size have included both mass and morphometrics, but these metrics may not equally or reliably estimate body size for all bee species and in all situations, due to bee age, diet, and/or environment. Understanding the relationships between different metrics and possible redundancies in the information they afford is important but not always known. Body size measurements provide valuable data for interpreting research outcomes for managed solitary bees, including Osmia lignaria Say and Megachile rotundata F. (Hymenoptera: Megachilidae). Applied studies of these important and readily available U.S. crop pollinators focus on refining commercial management practices, and basic empirical studies in various scientific disciplines (from genomics to ecology) employ them as model systems to study solitary bees. To examine common metrics of body size, we measured head capsule width (HCW), intertegular distance (ITD), and fresh and dry weights of newly emerged adults of both species. Using linear and exponential models, we determined relationships between these body size metrics. For M. rotundata, linear models best described relationships between ITD and all other metrics, and between HCW and fresh and dry weights. For O. lignaria, linear models best fit relationships between all metrics except for fresh weight with both ITD and HCW, which were fitted better with exponential models. For both species, model fits were strongest when males and females were pooled. Depending on the study question, knowing that only one metric may reliably measure body size can simplify evaluations of O. lignaria and M. rotundata responses to artificial or environmental variables.

Cataract Surgery Redesign: Meeting Increasing Demand, Training, Audit and Patient-Centered Care.

OBJECTIVE: The demand for cataract surgery in Fife (a well-defined region in southeast Scotland) was steadily increasing over 15 years. Cataract surgery was therefore being outsourced to meet demand with consequences on list mix, training needs, patient experience and staff morale. We aimed to redesign our services to meet local demand, retain a patient-centered service and continue to fulfil training needs. METHODS: We quantified cataract surgery delivery over an 18-month period: before, during and after redesign of services. We studied numbers of operations, trainee cases and number of outsourced cases. We also considered the economic implications of the redesign. RESULTS: We studied three periods (each of six months duration): before redesign (BR), redesign period (RP) and post-redesign (PR). Data were collected on total operation numbers, number of cases performed by trainees, and numbers performed out with normal working hours (weekend lists) and external providers. An economic analysis examined the cost of outsourcing cataracts during BR and RP and the costs of the redesign, including building, equipment and additional nursing staff. CONCLUSION: Regional fulfilment of cataract surgery provision remains a continuous challenge within the NHS. We show that with minimal investment, smart redesign process and collaborative working, increased local provision is possible while fulfilling trainee needs and achieving the necessary clinical audits and national standards.

Wildflower plantings promote blue orchard bee, Osmia lignaria (Hymenoptera: Megachilidae), reproduction in California almond orchards.

Concerns over the availability of honeybees (Apis mellifera L.) to meet pollination demands have elicited interest in alternative pollinators to mitigate pressures on the commercial beekeeping industry. The blue orchard bee, Osmia lignaria (Say), is a commercially available native bee that can be employed as a copollinator with, or alternative pollinator to, honeybees in orchards. To date, their successful implementation in agriculture has been limited by poor recovery of bee progeny for use during the next spring. This lack of reproductive success may be tied to an inadequate diversity and abundance of alternative floral resources during the foraging period. Managed, supplementary wildflower plantings may promote O. lignaria reproduction in California almond orchards. Three wildflower plantings were installed and maintained along orchard edges to supplement bee forage. Plantings were seeded with native wildflower species that overlapped with and extended beyond almond bloom. We measured bee visitation to planted wildflowers, bee reproduction, and progeny outcomes across orchard blocks at variable distances from wildflower plantings during 2015 and 2016. Pollen provision composition was also determined to confirm O. lignaria wildflower pollen use. Osmia lignaria were frequently observed visiting wildflower plantings during, and after, almond bloom. Most O. lignaria nesting occurred at orchard edges. The greatest recovery of progeny occurred along the orchard edges having the closest proximity (80 m) to managed wildflower plantings versus edges farther away. After almond bloom, O. lignaria nesting closest to the wildflower plantings collected 72% of their pollen from Phacelia spp., which supplied 96% of the managed floral area. Phacelia spp. pollen collection declined with distance from the plantings, but still reached 17% 800 m into the orchard. This study highlights the importance of landscape context and proximity to supplementary floral resources in promoting the propagation of solitary bees as alternative managed pollinators in commercial agriculture.

Assessing blue orchard bee (Osmia lignaria) propagation and pollination services in the presence of honey bees (Apis mellifera) in Utah tart cherries.

Osmia lignaria is a commercially available, native solitary bee species recognized for its propensity to forage upon and pollinate tree fruit crops such as apple, almond and cherry. This study evaluated the implementation of O. lignaria co-pollination with honey bees in central Utah commercial tart cherry orchards during 2017 and 2018 bloom. Three paired 1.2 ha sites were selected for evaluation of cherry fruit set and yield with and without managed O. lignaria releases alongside the standard honey bee hive stocking rate of 2.5 hives/ha. Osmia lignaria supplementation did not measurably increase cherry fruit set, fruit per limb cross-sectional area or fruit weight. The lack of differences in yield is likely a consequence of local saturation of pollinator services supplied by managed honey bees throughout experimental orchards, such that no additive benefit of managed O. lignaria releases were measurable. An increase in managed O. lignaria populations was achieved in 2017 but not 2018, possibly due to unknown changes to orchard management or environmental factors. While flying O. lignaria in Utah tart cherries may support sustainable in-field bee propagation, their subsequent impacts on tart cherry yield were not detected when paired with standard stocking densities of honey bees.

Pesticide Exposure Assessment Paradigm for Solitary Bees.

Current pesticide risk assessment for bees relies on a single (social) species, the western honey bee, Apis mellifera L. (Hymenoptera: Apidae). However, most of the >20,000 bee species worldwide are solitary. Differences in life history traits between solitary bees (SB) and honey bees (HB) are likely to determine differences in routes and levels of pesticide exposure. The objectives of this review are to: 1) compare SB and HB life history traits relevant for risk assessment; 2) summarize current knowledge about levels of pesticide exposure for SB and HB; 3) identify knowledge gaps and research needs; 4) evaluate whether current HB risk assessment schemes cover routes and levels of exposure of SB; and 5) identify potential SB model species for risk assessment. Most SB exposure routes seem well covered by current HB risk assessment schemes. Exceptions to this are exposure routes related to nesting substrates and nesting materials used by SB. Exposure via soil is of particular concern because most SB species nest underground. Six SB species (Hymenoptera: Megachilidae - Osmia bicornis L., O. cornifrons Radoszkowski, O. cornuta Latreille, O. lignaria Say, Megachile rotundata F., and Halictidae - Nomia melanderi Cockerell) are commercially available and could be used in risk assessment. Of these, only N. melanderi nests underground, and the rest are cavity-nesters. However, the three Osmia species collect soil to build their nests. Life history traits of cavity-nesting species make them particularly suitable for semifield and, to a lesser extent, field tests. Future studies should address basic biology, rearing methods and levels of exposure of ground-nesting SB species.

Workshop on Pesticide Exposure Assessment Paradigm for Non-Apis Bees: Foundation and Summaries.

Current pesticide risk assessment practices use the honey bee, Apis mellifera L., as a surrogate to characterize the likelihood of chemical exposure of a candidate pesticide for all bee species. Bees make up a diverse insect group that provides critical pollination services to both managed and wild ecosystems. Accordingly, they display a diversity of behaviors and vary greatly in their lifestyles and phenologies, such as their timing of emergence, degree of sociality, and foraging and nesting behaviors. Some of these factors may lead to disparate or variable routes of exposure when compared to honey bees. For those that possess life histories that are distinct from A. mellifera, further risk assessments may be warranted. In January 2017, 40 bee researchers, representative of regulatory agencies, academia, and agrochemical industries, gathered to discuss the current state of science on pesticide exposure to non-Apis bees and to determine how well honey bee exposure estimates, implemented by different regulatory agencies, may be protective for non-Apis bees. Workshop participants determined that although current risk assessment procedures for honey bees are largely conservative, several routes of exposure are unique to non-Apis bees and warranted further investigation. In this forum article, we discuss these key routes of exposure relevant to non-Apis bees and identify important research gaps that can help inform future bee risk assessment decisions.

A Nonlethal Method to Examine Non-Apis Bees for Mark-Capture Research.

Studies of bee movement and activities across a landscape are important for developing an understanding of their behavior and their ability to withstand environmental stress. Recent research has shown that proteins, such as egg albumin, are effective for mass-marking bees. However, current protein mass-marking techniques require sacrificing individual bees during the data collection process. A nonlethal sampling method for protein mark-capture research is sorely needed, particularly for vulnerable, sensitive, or economically valuable species. This study describes a nonlethal sampling method, in which three non-Apis bee species (Bombus bifarius Cresson [Hymenoptera: Apidae], Osmia lignaria Say [Hymenoptera: Megachilidae], and Megachile rotundata Fabricius [Hymenoptera: Megachilidae]) were tested for a unique protein marker by immersing them momentarily in saline buffer and releasing them. Results showed that an egg albumin-specific enzyme-linked immunosorbent assay was 100% effective at detecting the protein on bees that were sampled nonlethally. Furthermore, this sampling method did not have an impact on bee survivorship, suggesting that immersing bees in buffer is a reliable and valid surrogate to traditional, destructive sampling methods for mark-capture bee studies.

Examination of a Managed Pollinator Strategy for Almond Production Using Apis mellifera (Hymenoptera: Apidae) and Osmia lignaria (Hymenoptera: Megachilidae).

Pollination services provided by managed bees are essential for California almond (Prunus dulcis Mill.; Rosales: Rosaceae) production. Currently, pollination needs are met by rented or owned Apis mellifera L. (Hymenoptera: Apidae; honey bee) colonies. Excessive demand on a challenged A. mellifera industry to provide strong colonies in early spring has caused sharp increases in rental prices over the past decade, inviting the consideration of alternative pollinators in addition to, or in place of, A. mellifera. Osmia lignaria Say (Hymenoptera: Megachilidae; the blue orchard bee) is an excellent pollinator of fruit and nut trees, but its pollination impacts when used in tandem with A. mellifera have yet to be evaluated in commercial almond orchards. A 2-yr study was conducted in California orchards to compare almond pollination and production using A. mellifera as sole pollinator to an alternative practice of adding O. lignaria as a co-pollinator with A. mellifera. Almond orchard managerial decisions, such as for pesticide use and irrigation intensity, vary between almond growing regions because of local climates. Therefore, both north-central and southern sites of California's San Joaquin Valley are represented. We compared bee visitation, nut set, and nut yield between orchards and between tree rows within orchards. Also, O. lignaria reproductive success was recorded to assure that these bees remained in the orchards as pollinators and to assess the ability to sustain these bees under regional orchard conditions. We demonstrated that augmenting large commercial almond orchards with O. lignaria can significantly increase nut set and sometimes nut yield in both regions evaluated.

Wildflower Plantings Do Not Compete With Neighboring Almond Orchards for Pollinator Visits.

The engineering of flowering agricultural field borders has emerged as a research and policy priority to mitigate threats to pollinators. Studies have, however, rarely addressed the potential that flowering field borders might compete with neighboring crops for pollinator visits if they both are in bloom at the same time, despite this being a concern expressed by growers. We evaluated how wildflower plantings added to orchard borders in a large (512 ha) commercial almond orchard affected honey bee and wild bee visitation to orchard borders and the crop. The study was conducted over two consecutive seasons using three large (0.48 ha) wildflower plantings paired with control orchard borders in a highly simplified agricultural landscape in California. Honey bee (Apis mellifera L.) and wild bee visitation to wildflower plots were at least an order of magnitude higher than to control plots, but increased honey bee visitation to wildflower plots did not lead to any detectable shifts in honey bee visitation to almond flowers in the neighboring orchard. Wild bees were rarely observed visiting almond flowers irrespective of border treatment, indicating a limited short-term potential for augmenting crop pollination using wild bees in highly simplified agricultural landscapes. Although further studies are warranted on bee visitation and crop yield from spatially independent orchards, this study indicates that growers can support bees with alternative forage in almond orchards without risking competition between the wildflower plantings and the crop.

Migratory Bee Hive Transportation Contributes Insignificantly to Transgenic Pollen Movement Between Spatially Isolated Alfalfa Seed Fields.

Contracted commercial beekeeping operations provide an essential pollination service to many agricultural systems worldwide. Increased use of genetically engineered crops in agriculture has raised concerns over pollinator-mediated gene flow between transgenic and conventional agricultural varieties. This study evaluated whether contracted migratory beekeeping practices influence transgenic pollen flow among spatially isolated alfalfa fields. Twelve honey bee (Apis mellifera L.) colonies were permitted to forage on transgenic alfalfa blossoms for 1 wk in Touchet, WA. The hives were then transported 112 km to caged conventional alfalfa plots following one and two nights of isolation (8 and 32 h, respectively) from the transgenic source. Alfalfa seed harvested from the conventional plots was assessed for the presence of the transgene using a new seedling germination assay. We found that 8 h of isolation from a transgenic alfalfa source virtually eliminated the incidence of cross-pollination between the two varieties.

Cataract surgery: factors influencing decision to treat and implications for training (south-east Scotland 2008-2014).

PURPOSE: To describe the population referred for cataract surgery, identify factors that influenced decision to treat, and patients suitable for ophthalmic training. PATIENTS AND METHODS: A total of 2,693 consecutive referrals over 6 years were interrogated using Business Objects software on cataract electronic patient records. RESULTS: A total of 2,693 patients were referred for cataract surgery (group A). Of these patients 2,132 (79%) had surgery (group B) and 561 (21%) did not (group C). Age for group B vs group C: 672 (32%) vs 115 (20%) ≤69 years, P<0.001; 803 (38%) vs 225 (40%) 70-79 years, P=0.48; 586 (27%) vs 203 (36%) 80-89 years, P<0.05; 71 (3%) vs 18 (3%) ≥90 years, P=1.0. Visual acuity, group B vs group C: 556 (26%) vs 664 (59%) 6/12 or better; 1,275 (60%) vs 367 (33%) 6/18-6/60; 266 (12%) vs 64 (6%) counting fingers or worse, P<0.05. Medical history for group B vs C: cognitive impairment: 55 (2.6%) vs 29 (5.2%), P<0.05; cardiovascular accident: 158 (7.4%) vs 60 (10.7%), P<0.05; diabetes: 372 (17.4%) vs 96 (17.1%), P=0.87; COPD/asthma: 382 (17.9%) vs 93 (16.6%), P=0.53; heart disease: 535 (25.1%) vs 155 (27.6%), P=0.35; hypertension: 971 (45.5%) vs 263 (46.9%), P=0.73. Ocular history for group B vs C was significant (P<0.05) for age-related macular degeneration 255 (12.0%) vs 93 (16.6%), other macular pathology 38 (1.8%) vs 25 (4.5%), corneal pathology 92 (4.3%) vs 36 (6.4%), amblyopia 37 (1.7%) vs 22 (3.9%). Detailed data on presenting complaint, ophthalmic history, and social status is discussed. CONCLUSION: We observed that surgery at a younger age with good levels of visual acuity was a factor in deferring cataract surgery. Cognitive impairment, cardiovascular accident, amblyopia, corneal and macular pathology significantly affected decision not to operate. We estimate that 80% of patients would be suitable for ophthalmic training.

Symptomatic excyclotorsion following inferior transposition of both medial rectus muscles in patients with bilateral trochlear nerve palsy.

PURPOSE: To report the development of a large degree of excyclotorsion following inferior transposition of the medial rectus muscles in 5 patients with bilateral acquired trochlear nerve palsies that had previously undergone bilateral modified Harada-Ito procedures. METHODS: The medical records of 5 patients who had undergone Harada-Ito procedure for bilateral trochlear nerve palsy between 2002 and 2010 and medial rectus muscle infraplacement surgery between 2004 and 2012 were retrospectively reviewed. RESULTS: All 5 patients underwent a Fells-modified Harada-Ito procedure. All remained symptomatic due to a V pattern (eso- or exodeviation). Bilateral inferior transposition of the medial rectus muscles of either half or full tendon width was performed to alleviate this residual diplopia. The vertical transposition resulted in a symptomatic large degree of excyclotorsion (mean of 20°), which required reversal of the procedure. CONCLUSIONS: After inferior transposition of both medial rectus muscles in patients with bilateral superior oblique palsy who previously had bilateral modified Harada-Ito surgery, a large excyclotorsion (>20°) can occur. This can be managed by reversing the medial rectus transposition procedure.

Full-tendon nasal transposition of the vertical rectus muscles: a retrospective review.

The authors report the results of a retrospective review of patients who underwent nasal transposition of the vertical rectus muscles between 1997 and 2004. Eight patients were identified, 4 males and 4 females. There was an average age at surgery of 37 years, with a range from 8 to 79 years. The aetiologies included 6 patients with trauma to their medial rectus (4 following endoscopic sinus surgery) and 2 patients with paralytic medial rectus muscles secondary to 3rd nerve palsy. All patients underwent whole tendon transposition of the superior and inferior rectus muscles, with resection of both muscles in 7 cases, before reattachment adjacent to the upper and lower borders of the medial rectus, respectively. One patient had a reduced amount of resection and this was combined with inferior oblique disinsertion and traction sutures. All patients had a reduction in deviation in the primary position and in 5 patients there was some improvement in adduction. A consequence of surgery was a degree of limitation of abduction, elevation and depression in some patients. Overall, patients were satisfied with the improvement in their appearance.

Use of the combined recession and resection of a rectus muscle procedure in the management of incomitant strabismus.

BACKGROUND: Scott described a method of achieving the effect of a posterior fixation procedure by combining resection and recession of a rectus muscle, while maintaining the ability to adjust primary position alignment with adjustable sutures. METHODS: A retrospective review of combined recession-resection procedures on rectus muscles between 1998 and 2002 was carried out. RESULTS: We identified 22 patients, 17 females and 5 males. The mean age at presentation was 44 years. The etiology was felt to be paralytic in seven patients (31.8%), mechanical/restrictive in seven patients (31.8%), and due to residual childhood strabismus in eight patients (36.4%). Twenty patients had undergone previous strabismus surgery, ranging from one to six operations (mean, 1.75). Scott procedures were performed on 25 rectus muscles of 22 patients; 12 on the lateral rectus muscles, 7 on the inferior rectus muscles, 3 on the medial rectus muscles, and 3 on the superior rectus muscles. All but one patient had a measurable improvement in gaze incomitance, and 11 of 12 who had a measurement of the field of binocular single vision showed improvement. Twenty patients had follow-up periods of 3 months or more, with a range of 3 to 30 months and a mean of 9.35 months. CONCLUSIONS: The combined recession-resection procedure advocated by Scott has a role in the management of incomitant strabismus.

Benefits of retroequatorial four horizontal muscle recession surgery in congenital idiopathic nystagmus in adults.

INTRODUCTION: Four muscle surgery for congenital nystagmus was originally described in 1956 and popularized by two articles in the 1990s. A review of the literature revealed only three studies of seven, nine, and six patients published since then. We therefore reviewed our patients to determine the objective and subjective benefits of this procedure. METHODS: A retrospective review was carried out on patients who underwent bilateral maximal horizontal muscle recessions for congenital nystagmus between 1997 and 2002. Improvement in visual acuity was documented. An external assessor administered an anonymized questionnaire to discover any perceived benefit. Eighteen patients were identified, 12 men and 6 women, with an average age at surgery of 32 years. RESULTS: Preoperative visual acuity ranged from 6/9 binocularly to 6/60. All underwent bilateral medial rectus muscle recessions of 8 mm to 10 mm and bilateral lateral rectus muscle recessions of 8 mm to 12 mm. Nine patients (50%) gained one line of Snellen visual acuity. There were four complications: one scleral perforation; two developed exotropia; and one complained of asthenopic symptoms. This latter patient was the only one who experienced some deterioration of vision acuity. Fourteen of 18 (78%) questionnaires were returned. Eight patients said they were pleased; four were indifferent and two were displeased. CONCLUSIONS: We conclude that this operation delivers limited objective benefit. None of our patients were able to obtain a driving license. Fifty-seven percent of patients expressed the view that they were glad to have had the surgery, although the visual improvement was only slight.

Blindsight in children: does it exist and can it be used to help the child? Observations on a case series.

Damage to the occipital lobe of the brain results in hemianopia when unilateral, and cerebral blindness when bilateral. However, in some cases a degree of visual function persists in the blind visual field. This aim of this study was to describe this phenomenon of 'blindsight' in a cohort of children with brain-damage and to relate the clinical features to their visual evoked potentials. We performed a retrospective analysis of 541 case records of children referred to a tertiary vision-assessment clinic in the Royal Hospital for Sick Children, Glasgow, UK from 1992 to 2002. A total of 541 patients were analyzed (243 females, 298 males; age range 2 mo to 19 y 6 mo, mean 6 y 2 mo). In 19 children with profound visual impairment and four children with hemianopia (12 females, 11 males; age range 1 to 18 y, mean age 8 y 3 mo), evidence of perception of movement in the blind visual field was found and is described. Flash visual evoked potentials varied from no response to normal and was not correlated with visual behaviour. Recognition, detection, and use of this phenomenon in children is vital to their rehabilitation and interaction with their surroundings.