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Injection of botulinum neurotoxin A (BoNTA) to the lacrimal gland (LG) offers a simple and effective treatment in the management of epiphora. However, there is little data on current practice trends or uptake as an alternative to surgery. This study assesses current practice trends of such treatment amongst BOPSS (British Oculoplastic Surgery Society) members. All consultant BOPSS members were invited to participate in a web-based survey which consisted of 5 questions, with a reminder invitation to participate. The role, dose, potential side effects, use as an alternative to surgical intervention, and impact on service delivery were assessed. Fifty-one BOPSS consultants (43% uptake) completed the survey. Ninety percent of respondents were regularly using LG BoNTA in their management of epiphora. The main indicators for considering BoNTA use were medical comorbidities and elderly patients. The mean first treatment dose of Botox® was 3.6 units (SD 1.5). Diplopia and ptosis complications were always discussed in the consent for treatment in addition to dry eye. Twenty-five percent of surgeons reported doing less conjunctivo-dacryocystorhinostomies (cDCR) due to the availability of LG BoNTA. No respondents felt that the requirement for repeated BoNTA treatments was impacting on their service delivery. Uptake of LG BoNTA in the management of epiphora is at a similar rate to all other available treatments. As a result, respondents are performing less surgical procedures, particularly cDCR in patients at higher surgical morbidity.

The lower eyelid changes with aging include atrophy of the orbital septum with subsequent forward herniation of orbital fat, descent of the sub-orbicularis oculi muscle fat, ptosis of the orbicularis oculi muscle, weakening of the orbito-malar ligament and the development of laxity of the eyelid skin, the tarsus and the canthal tendons. In this article we aim at describing our experience of using a modified lower lid blepharoplasty with fat repositioning in patients with lower lid fat prolapse and tear trough deformity. A retrospective, non-randomised non-comparative interventional consecutive case series of patients seeking surgical treatment. Patients underwent surgery between April 2010 and October 2019 by a single surgeon (BL). Patient demographics, clinical examination, preoperative and postoperative clinical photography, outcomes and complications were recorded. Follow-up was initially at 2 weeks and finally at 16–20 weeks. Outcomes were recorded as subjective improvement and degree of patient satisfaction. A total of 150 patients were recruited in the study period. The mean age at the time of surgery was 49. One hundred forty-one (94%) patients were very satisfied with the final outcome of their surgery, 5 were satisfied and 4 were dissatisfied. One patient developed a bilateral lower lid infection requiring abscess drainage. Seventeen other patients experienced minor complications in the postoperative period, including 2 with a unilateral lower lid infection requiring oral antibiotics, 3 with a temporary inferior oblique palsy, 1 with temporary unilateral infraorbital nerve dysfunction, 3 with residual prolapses of the lateral fat pads, 1 with a medial lower lid lump, 2 with a conjunctival granuloma, 2 with a temporary medial ectropion, 1 with persistent unilateral lower lid oedema, 1 with persistent bilateral lower lid oedema and 1 with unilateral lower lid retraction. We report a high patient satisfaction with a low rate of significant complications following our modified lower lid transconjunctival blepharoplasty with fat repositioning. Level of evidence: Level III, therapeutic study

Surgical resection of spheno-orbital meningioma (SOM) is challenging, requiring a multidisciplinary surgical approach. We present our experience of the surgical management of patients with SOM.A retrospective analysis of patients with SOM who underwent joint neurosurgical and orbital surgical procedures between January 2000 and June 2017. Pre-operative clinical signs, indication for surgery, surgical complications and post-operative outcomes were recorded.Twenty-four operations were performed. Mean age was 49.5 years. Ninety-two percent of patients were female. Pre-operatively mean Snellen acuity vision was 6/12; 13 (54%) had an RAPD; 12 (50%) had reduced colour vision; 16 (67%) had a visual field defect. The majority (21 patients, 88%) had proptosis (average 4.5 mm ± 2.8 mm). The indication for surgery was evidence of visual dysfunction in 17 (71%), the remaining 7 (29%) had high risk of visual loss clinically or radiologically. Three-months post operatively, vision was stable in 13 (58%), improved in 6 (21%) and worse in 5 (17%). Average long-term follow-up was 82 months (1-220). Fourteen (58%) maintain improved or stable visual function. Four (17%) had reduced vision due to regrowth of the tumour at an average of 24 months.SOMs are very challenging to treat surgically. In this cohort the patients were predominantly young females with aggressive disease. Visual function was improved or stabilised in 79% of the patients.

Injection of botulinum neurotoxin A (BoNTA) to the lacrimal gland (LG) offers a simple and effective treatment in the management of epiphora. However, there is little data on current practice trends or uptake as an alternative to surgery. This study assesses current practice trends of such treatment amongst BOPSS (British Oculoplastic Surgery Society) members.All consultant BOPSS members were invited to participate in a web-based survey which consisted of 5 questions, with a reminder invitation to participate. The role, dose, potential side effects, use as an alternative to surgical intervention, and impact on service delivery were assessed.Fifty-one BOPSS consultants (43% uptake) completed the survey. Ninety percent of respondents were regularly using LG BoNTA in their management of epiphora. The main indicators for considering BoNTA use were medical comorbidities and elderly patients. The mean first treatment dose of Botox® was 3.6 units (SD 1.5). Diplopia and ptosis complications were always discussed in the consent for treatment in addition to dry eye. Twenty-five percent of surgeons reported doing less conjunctivo-dacryocystorhinostomies (cDCR) due to the availability of LG BoNTA. No respondents felt that the requirement for repeated BoNTA treatments was impacting on their service delivery.Uptake of LG BoNTA in the management of epiphora is at a similar rate to all other available treatments. As a result, respondents are performing less surgical procedures, particularly cDCR in patients at higher surgical morbidity.

Mixed tumour of the skin is a rare entity also known as chondroid syringoma and pleomorphic adenoma. These usually present as slow-growing skin nodules with a smooth surface, clear boundaries, and no ulceration. Case series exist describing pleomorphic adenomas in the periocular region including the lids and orbit, separate to the more familiar lacrimal gland pleomorphic adenoma. These may arise from accessory or ectopic lacrimal gland tissue but in the eyelids are more likely to arise from sweat glands in the skin. Histopathological analysis of these lesions is important to identify complete excision, minimising recurrences and in identifying rare but potential malignant transformation. We describe the clinical features and outcomes in three cases of pleomorphic adenoma with two at the medial canthus (including one recurrence) and one in the brow region.

With support from the NASA sounding rocket program, the Air Force Research Laboratory (AFRL) launched two sounding rockets in the Kwajalein Atoll, Marshall Islands in May 2013 known as the Metal Oxide Space Cloud (MOSC) experiment. The rockets released samarium metal vapor at preselected altitudes in the lower F-region that ionized forming a plasma cloud. Data from ALTAIR incoherent scatter radar and high frequency (HF) radio links have been analyzed to understand the impacts of the artificial ionization on radio wave propagation. The HF radio wave ray-tracing toolbox PHaRLAP along with ionospheric models constrained by electron density profiles measured with the ALTAIR radar have been used to successfully model the effects of the cloud on HF propagation. Up to three new propagation paths were created by the artificial plasma injections. Observations and modeling confirm that the small amounts of ionized material injected in the lower-F region resulted in significant changes to the natural HF propagation environment.

Introduction: The authors describe benefits of the recognised adverse effects of prostaglandin analogues on periocular structures in patients with unilateral proptosis and intraocular pressure rise. This case points to intentional consideration of prostaglandin analogue therapy in this selected cohort of patients with secondary ocular hypertension and proptosis. Case description: A 70-year-old gentleman who presented with a 1-week history of a red and painful right eye associated with tortuous and dilated episcleral blood vessels. Visual acuity was unaffected. A diagnosis of idiopathic orbital inflammatory disease was made by extraocular muscle biopsy. Two weeks later, the patient presented with worsening pain, reduced vision and raised intraocular pressure. The secondary ocular hypertension was successfully treated with topical preserved eye drops, including latanoprost, a prostaglandin analogue. Over 6 months, the patient developed drop intolerance and punctate keratopathy leading to therapy non-adherence. Interestingly, the patient reported improvement in periocular appearance related to prostaglandin-associated periorbitopathy. Ocular surface disease and intraocular pressures were subsequently managed with preservative-free eye drops. Conclusion: Secondary ocular hypertension is not an uncommon consequence of orbital disease. Prostaglandin analogue can act as a double-edged sword in the management of raised intraocular pressure by reducing eye pressure at the cost of developing adverse effects of prostaglandin-associated periorbitopathy. These adverse effects however can be beneficial in the aesthetic rehabilitation of proptosis and associated exposure keratopathy in patients with unilateral orbital disease and probably should be sought as first line treatment in those with proptosis and raised intraocular pressure.

Ultrahigh frequency space-based synthetic aperture radar (SAR) can suffer from the degrading effects of a scintillating ionosphere which modulates both the phase and the amplitude of the radar signal. In this paper, we use Global Navigation Satellite System (GNSS) signals to synthesize an L-band SAR point spread function (PSF). The process of transforming the GNSS signal to the equivalent SAR PSF is described. The synthesized PSF is used to explore the possibility of using a phase correction determined from a point target in a SAR image to correct the ionospheric degradation. GNSS data recorded on equatorial Ascension Island during scintillation events are used to test the feasibility of this approach by applying a phase correction to one GNSS receiver from another located along a magnetic east-west baseline. The peak-to-sidelobe ratios of the synthesized L-band SAR point spread functions before and after the correction are compared, and it is shown that this approach improves the L-band PSF over distances of ~3000 m in the ionosphere, corresponding to 6000 m on the ground.

Space-based low-frequency synthetic aperture radar (SAR) is affected by the ionosphere, which induces both phase and amplitude fluctuations, known as scintillation, into the radar signal. This paper describes the effect of amplitude scintillation on SAR imagery. The two-way amplitude and intensity probability density functions (pdf) for both monostatic and bistatic SAR are derived from the one-way Nakagami-m distribution. The moments are then used to determine the SAR radiometric calibration error and image contrast from the one-way S 4 index. It is also shown that monostatic SAR experiences an S 4-dependent radar cross-section (RCS) enhancement that is not experienced by bistatic SAR. The anisotropy of the ionospheric irregularities strongly affects the degree to which amplitude scintillation will be visible in SAR imagery. The description of anisotropic effects is reviewed and extended to cover SAR. The variation over the Earth is illustrated, showing that a sun-synchronous satellite will experience the strongest effect near Brazil. Two PALSAR images of the same area of Brazilian rainforest are compared, one of which shows azimuthal streaking, corresponding to an amplitude modulation of ± 1 dB. The one-way S 4 index is determined from this imagery using both the RCS enhancement and image contrast measures of S 4, which produce similar results.

Low-frequency space-based synthetic aperture radar (SAR) is an ideal sensor for measuring forest biomass, but can suffer from ionospheric effects. The variation in total electron content (TEC), originating from ionospheric turbulence, causes the along track point spread function (PSF) to degrade in a manner which depends on ionospheric conditions. In this study, the effect of this PSF on the single point statistics (probability density function) and two point statistics (autocorrelation function (ACF)) is derived. It is shown that the K -distribution order parameter is directly proportional to the ionospheric turbulence, as quantified by C k L . The complex ACF is a measure of amplitude scintillation, and the intensity ACF is a measure of both the order parameter and the terrain correlation length. A simulation is performed which clearly shows that measuring the order parameter ratio between ionospherically disturbed and undisturbed images is a measure of C k L . This measure can be used two orders of magnitude below the point where the ionosphere causes defocusing of the SAR image. It is concluded that the usefulness of this new measure can only be verified by experimental data since the temporal stability of the underlying order parameter is unknown.

Purpose: There is a paucity of published data on the management of upper eyelid cicatricial entropion. We report on our results using such techniques as lamella repositioning, recession or augmentation and terminal tarsal rotation. Design: Observational retrospective case series. Participants: Consecutive cases of upper eyelid cicatricial entropion of two specialist oculoplastic centres (Corneoplastic Unit, East Grinstead, UK and South Australian Institute of Ophthalmology, Adelaide, Australia) were reviewed over a 7-year period. Methods: All patients underwent anterior lamellar repositioning or terminal tarsal rotation. Main Outcome Measures: Success was defined by two definitions: anatomical success was defined where the lid margin was restored to its normal position. Complete success was defined where there were no eyelashes touching the globe. Gain or loss (≤ or ≥2 Snellen lines) in best corrected visual acuity using a Snellen chart and resolution of any corneal epitheliopathy at final follow-up were also recorded (as graded by experienced oculoplastic consultants). Results: Fifty-two procedures were performed on 41 patients (11 bilateral). All patients underwent either an anterior lamellar repositioning or a terminal tarsal rotation. Trachoma, previous upper lid surgery, Stevens–Johnson syndrome and meibomian gland dysfunction were the commonest underlying diagnoses. Ninety-eight per cent of the group had a normal anatomical lid position at follow-up. Nine eyelids (17%) of the group had recurrence of trichiasis. Conclusion: This large case series demonstrates that upper eyelid cicatricial entropion is managed effectively utilizing procedures that involve recession and reposition. We recommend that excision of tissue is avoided, especially in pathology that has a progressive immunological cicatricial drive.

To investigate the effects of Merogel coverage on ostial patency in endonasal endoscopic dacryocystorhinostomy (EES-DCR) for primary chronic dacryocystitis (PCD).In all, 260 patients with unilateral PCD were randomized into two groups: the Merogel group and the control group. All patients underwent EES-DCR. The Merogel group received Merogel covering the wound 1-2 mm around the ostium and the control group received no treatment. Patients were followed up for 9 months. The mucosal epithelialization of the wound, the proliferation of fibrosis tissue, and the success rate of ostial patency were compared.Our study included 112 patients in the Merogel group and 115 patients in the control group. At the 2-week review, intact mucosal epithelium lined the ostia in 96 Merogel patients compared with 80 control patients (ITT analysis: χ(2)=4.502, P=0.034). At the 9-month review, scars were present in 18 patients in the Merogel group compared with 39 patients in the control group (ITT analysis: χ(2)=9.909, P=0.002, ITT analysis). No differences were observed in the granulation formation between the two groups. The success rate of ostial patency reached 94.6% (106/112) in the Merogel group compared with 80% (92/115) in the control group (ITT analysis: χ(2)=4.151, P=0.042).Merogel coverage may enhance the success rate of EES-DCR for PCD by promoting mucosal epithelial healing and preventing excessive scarring.

Purpose: To assess the combination of an endoscopic transethmoidal approach (ETEA) and a transconjunctival inferior fornix approach (TIFA) for repairing combined orbital floor and medial wall blowout fractures (COF-MWBOFs). Methods: Patients with unilateral COF-MWBOFs were randomized to 2 groups: ETEA combined with TIFA or medial canthal incision (MCI) combined with TIFA. Thin porous polyethylene sheets were implanted to cover the orbital defects. The postoperative follow-up time was 6 months. For both groups, degree of diplopia, enophthalmos, ocular motility, and complications were recorded and compared. Results: Our study included 32 patients in the ETEA group and 27 patients in the MCI group. The time from trauma to surgery ranged from 10 to 48 days. The herniated orbital contents were completely reduced in 96.9% (31/32) of the ETEA group and in 77.8% (21/27) of the MCI group (P = 0.040). At the 6-month review, the success rate of enophthalmos correction in the ETEA group achieved 96% (24/25), higher than that in the MCI group (66.7%, 12/18; P = 0.015). The improvement of the enophthalmos was better in the ETEA group than in the MCI group (4.5 ± 0.7 mm versus 3.2 ± 1.2 mm) at 6 months (P = 0.000). We found no difference in the resolution rate of diplopia within a 30-degree visual field or extraocular muscle function between the 2 groups. Complications in the MCI group included 1 patient with optic neuropathy after the procedure and 4 patients with medial canthal webbing. Conclusions: Endoscopic transethmoidal approach combined with TIFA is a promising technique for repairing extensive COF-MWBOFs.

Aims To describe the outcomes and complications for composite eyelid grafts in a large case series over a 9-year period. Method A retrospective study of all patients who underwent a composite graft for eyelid reconstruction between January 2000 and May 2009. A composite eyelid graft involves the excision of a full thickness pentagonal wedge from the donor eyelid, which is inserted into the recipient eyelid defect. The orbicularis muscle is discarded from the composite graft. Initial diagnosis, complications, postoperative eyelid contour and colour were recorded. Results Forty-two patients were identified in the study period; the mean age was 69 years. Reconstruction following basal cell carcinoma excision was the commonest indication for surgery. Thirty-five composite grafts were performed for lower eyelid defects and seven for upper lid defects. The average size of the grafts was 9.1 (range 7–12) mm. Five patients required two grafts to reconstruct the defect. Thirty-six (86%) patients achieved a satisfactory contour and 33 (78%) patients had good matching skin colour. Partial dehiscence occurred in five patients and three patients had bulkiness of the graft postoperatively. We had no episodes of graft failure, although two patients had skin necrosis, which resolved. Conclusion Composite eyelid grafts when combined with mobilisation of the recipient orbicularis muscle can result in good preservation of eyelid function with satisfactory cosmesis.

An 80-year-old man presented with an 8-week history of painless swelling in the right lacrimal gland region with infero-medial dystopia of the globe. The lesion was excised and histology confirmed an orbital plasmacytoma. Multiple myeloma screening was negative and a solitary extramedullary plasmacytoma arising from the lacrimal gland was diagnosed. The patient was subsequently treated with radiotherapy.

AIM: To report a series of patients with lacrimal gland lesions simulating the clinicoradiological features of lacrimal gland pleomorphic adenoma (LGPA). METHODS: Multicentre retrospective, interventional case series. Clinical records of all patients with lesions mimicking LGPA seen in five orbital units were reviewed. RESULTS: The study included 14 patients (seven men and seven women) with a mean age of 50.9 years. The diagnosis of LGPA was made in all cases by experienced orbital surgeons, based on clinicoradiological features, and lacrimal gland excision was performed. Postoperative histology revealed lymphoma (four patients), chronic dacryoadenitis (three patients), adenoid cystic carcinoma (two patients), Sjogren's syndrome (two patients), cavernous haemangioma (one patient), benign lymphoid hyperplasia (one patient) and granulomatous dacryoadenitis (one patient). Comparison with the total number of histologically confirmed LGPA cases seen during the study period revealed that 22.6% of cases of suspected LGPA were misdiagnosed based on clinicoradiological criteria. CONCLUSIONS: Many different lesions may mimic the clinicoradiological features of LGPA. The accepted clinicoradiological criteria used for the diagnosis of LGPA have a high false-positive rate, even in experienced hands. Based on this study, the authors believe that fine-needle aspiration biopsy or intraoperative biopsy and frozen section diagnosis may help reduce unnecessary lacrimal gland excision.

Purpose: To describe the management of lower eyelid margin hypertrophy as a complication of the Hughes procedure for eyelid reconstruction. Methods: A retrospective review of all patients with lower eyelid hypertrophy after Hughes procedure. Patient demographics, management, histologic findings, and outcomes were recorded. The patients underwent wedge excision of the hypertrophic segment of the eyelid with direct closure achieved in the majority of cases. Results: Five patients were identified. The mean age at presentation was 66 years. The mean onset for the hypertrophic margin was 8.4 weeks after the Hughes flap. Four patients complained of ocular irritation and 1 patient had a constant ocular discharge. All patients were concerned by the appearance of the eyelid margin. Four patients received topical steroid treatment and 4 patients underwent triamcinolone subcutaneous injections with no improvement. The wedge excision was successful in 4 patients at the mean follow-up of 10 months, with no recurrence of the hypertrophic margin. One patient was reviewed in another center. Conclusion: The authors found no beneficial effect with topical or subcutaneous courses of steroids on eyelid margin hypertrophy. In situations of horizontal eyelid laxity, a full-thickness wedge excision offers a good means of removing the offending eyelid segment.

Aim To describe the ophthalmic side-effects of topical imiquimod for periocular actinic keratoses, squamous cell carcinoma in situ and basal cell carcinoma. Method A retrospective study was carried out in two centres of all patients who underwent topical imiquimod therapy between January 2004 and January 2009. Imiquimod was applied three times weekly for 4–6 weeks. Diagnosis of the lesions, complications, clinical resolution and long-term ophthalmic side-effects was recorded. Patients on therapy were reviewed fortnightly and then every 6 weeks following completion of treatment. Results 47 patients were identified; the mean age was 74 years. 37 patients had actinic keratoses, seven patients had Bowen disease, and three patients had BCC. The lower lid was the commonest site involved (68%). Application site erythema occurred in all patients. Conjunctivitis occurred in 15 patients, and six patients complained of ocular stinging on application of imiquimod. One patient had a staphylococcal keratitis, which responded to topical antibiotic and steroid therapy. Two patients required oral antibiotics for preseptal cellulitis. Three patients had delayed conjunctivitis at a mean of 2.3 weeks. Nine patients discontinued imiquimod due to ocular irritation and conjunctivitis, of whom four patients recommenced and finished the treatment after a rest period. At a mean follow-up of 16 weeks, 34 patients had clinical resolution of the periocular lesions and no patient had any residual ophthalmic side-effects from imiquimod. Conclusion Conjunctivitis and ocular stinging were the commonest ophthalmic side-effects encountered with the application of imiquimod for periocular skin lesions. These effects were temporary and resolved on terminating the imiquimod therapy.

BACKGROUND Botulinum toxin (BTX) is the first-line treatment in managing benign essential blepharospasm (BEB) and hemifacial spasm (HFS). We wished to assess the difference in duration of effect and the number of BTX treatments required to treat patients with BEB and HFS. METHODS A prospective study of patients attending the BTX clinic in Manchester Royal Eye Hospital over 6 months. All treatments were administered by a single experienced ophthalmologist. A questionnaire was completed for each patient. In patients with BEB where the BTX was injected bilaterally, one side was randomized to compare with HFS patients. Patient demographics, cumulative dose of BTX, duration of BTX effect with patient satisfaction and the number of previous BTX injections were recorded. RESULTS Sixty-four patients were included in the study. The mean age was 60.8 years. Among them, 30 patients had BEB and 34 had HFS. Patients with HFS received a lower mean dose of BTX than patients with BEB (12.23 units vs. 16.2 units). The patients with HFS had a longer duration of effect than patients with BEB, with fewer BTX treatments. Of all patients, 90% with HFS and BEB were satisfied with the effect of their last BTX injection. Three unsatisfied patients in the BEB group were referred on for surgical management of their disorder. CONCLUSIONS We have shown that patients with BEB have a shorter duration of effect with BTX and require more frequent BTX treatments than patients with HFS, highlighting that facial dystonias in patients with BEB is more challenging to manage.

High cadence GPS TEC signals collected on Ascension Island, South Atlantic Ocean, during sunspot minimum, and in Vanimo, Papua New Guinea, over half a solar cycle, have been analysed for their spectral properties. A new parameter Tk has been introduced to quantify the strength of TEC irregularities at a scale size of 1 km. The scintillation strength and the spectral index have been analysed as functions of each other, and of local time, season, location and sunspot number. The scintillation strength is highest in autumn and spring in both locations, although the quietest period is summer in Ascension and winter in Vanimo. The scintillation strength decreases with decreasing sunspot number, but is consistently lower in Vanimo than in Ascension. The spectral index decreases with scintillation strength, and increases during the hours of the evening. A method is developed to estimate Tk from the large data base of S4 measurements.

Orbital cellulitis is conventionally managed by intravenous (i.v.) antibiotic therapy, followed by oral antibiotics once the infection shows signs of significant improvement. We report 4 years of experience using primary oral ciprofloxacin and clindamycin in cases of orbital cellulitis. Oral ciprofloxacin and clindamycin have a similar bioavailability to the i.v. preparations and provide an appropriate spectrum of antibiotic cover for the pathogens responsible for orbital cellulitis.A retrospective review was performed that identified all patients with orbital cellulitis and treated with primary oral antibiotic therapy admitted to the Manchester Royal Eye Hospital between March 2003 and March 2007. Age, stage of disease, surgical intervention, hospital duration, and complications were obtained. A comparison was made with patients admitted to our unit with orbital cellulitis and treated with primary i.v. antibiotics between March 2000 and March 2003.Nineteen patients were included in the review for the period March 2003 to March 2007, which comprised of 7 children and 12 adults. Five patients required surgical intervention. All patients responded to the oral regimen, 18 patients had no change to their oral antibiotic therapy. Mean hospital stay was 4.4 days. There were no complications.Empirical oral ciprofloxacin and clindamycin combination may be as safe and effective as i.v. therapy in the management of orbital cellulitis. Oral treatment can offer the advantages of rapid delivery of the first antibiotic dose, fewer interruptions in treatment, and simplified delivery of medication particularly in children.

To report the clinical findings in two brothers presenting with a pigmentary retinopathy and post-axial polydactyly, who were found to have a mutation in the BBS1 gene, confirming a diagnosis of Bardet-Biedl syndrome (BBS).Documentation of the clinical history, electrophysiological investigations, clinical examination and ocular findings of two brothers born to non-consanguineous white parents, with careful delineation of their clinical phenotypes. Screening of the BBS 1 gene on chromosome 11q13 by PCR-amplified exon alterations followed by direct sequencing was carried out to identify pathogenic mutations.Although both probands had polydactyly and the characteristic ocular signs of BBS on both ophthalmological examination and electro-retinography, neither of them had dysmorphic facial features, obesity, hypogonadism, cognitive impairment, or renal anomalies. The first proband did have mild learning difficulties, although this did not restrict him in activities of daily living. Both probands were homozygous positive for the presence of a c.1169TG (p.Met390Arg) mutation in BBS1.Although neither proband fulfilled the typical criteria for BBS, this diagnosis was confirmed on mutation analysis. These cases serve to highlight the degree of clinical variability observed in BBS which may be under-diagnosed in patients with milder phenotypes.

We have examined the long time series of observations of E-region virtual height (1948–2006) and critical frequency (1935-2006) hitherto made by the Tromsø ionosonde at 70° N, 19° E. Combining a simplistic trend analysis with a rigorous treatment of errors we identify a negative trend in critical frequency. While a similar analysis of the virtual height h'E also suggests a negative trend, a closer examination reveals a possible weak positive trend prior to ~1975 and a strong negative trend from ~1975 to present. These two metrics of essentially the same feature of the ionosphere do not exhibit the same signature since critical frequency is controlled by photochemistry within the E-layer while height is controlled by pressure level. We further find that the trend in critical frequency is a daylight/summer phenomenon, no significant trend being evident in the winter subset of the data. On the other hand, the trends in virtual height are independent of season/daylight.

The effect of the ionosphere on SAR imaging has been studied previously from both an analytic and a numerical simulation perspective. Recently, effects visible in SAR imagery have been ascribed to turbulence in the ionosphere. This paper describes an experiment that seeks to use ground-based GPS measurements of the ionospheric scintillation, collected simultaneously with PALSAR-2 imagery, to unambiguously confirm the predictions of the analytic theory. PALSAR-2 (on board the ALOS-2 satellite) was used in spotlight mode to image a 5m corner reflector to obtain an accurate measurement of the point spread function (PSF). Initial results, obtained during the 2014/15 scintillation season, confirm that the analytic theory describing the shape of the SAR PSF is correct. This is then used to obtain two measures of the scintillation, p and C k L, directly from the PALSAR-2 PSF. The collected data set can also be used for further research into ionospheric autofocus techniques.

A unique resource providing continuous observations of the critical frequencies since 1935 and layer heights since 1952 has been used to determine the long-term trends above Tromso in Northern Norway (69°N, 19°E). These, and the recent results of Ulich et al. [Ulich, T., Cliverd, M.A., Rishbeth, H. Determining the long-term change in the ionosphere. EOS Trans. 84(52), 581–585, 2003] have then been used to illustrate the effects of layer height changes on radio system modelling and operation by reference to high frequency ground range and skip zone variations. The analysis ignores the effects of the variations in the underlying E-region and changes in the F2 layer critical frequencies. Consequently, the system impact is expected to be higher still. It is shown that a 16 km drop in h m F2 will introduce ground errors of ∼100 km with higher values under certain circumstances. The Tromso analysis indicate that these ground range errors will not occur until the year 2110, however, the results of Ulich et al. [EOS Trans. 84(52), 581–585, 2003] indicate that this condition occurred in the year 2000. This study demonstrates an urgent need to reach a consensus understanding of long-term ionospheric trends. A reassessment of the CCIR and URSI worldwide maps of ionospheric characteristics is likely necessary.

Space weather effects can strongly influence high-frequency (HF) communications by changing the ionospheric environment through which the radio waves propagate. Since many systems utilize HF communications, the ability to make real-time assessments of propagation conditions is an important part of space weather monitoring systems. In this paper, we present new techniques for measuring high-latitude HF communications link parameters using data from SuperDARN radars. These techniques use ground-scatter returns to define the variation in skip distance with frequency. From these data, the maximum usable frequency (MUF) as a function of range is determined and ionospheric critical frequencies are estimated. These calculations are made in near-real-time and the results are made available on the World Wide Web. F-region critical frequencies calculated using this method show good agreement with ionosonde data.Key words. Ionosphere (active experiments; instruments and techniques) – Radio science (ionospheric propagation)

A 59-year-old Chinese man presented with no light perception in the left eye 1 day following functional endoscopic sinus surgery. The patient underwent endoscopic optic nerve decompression with topical and systemic application of nerve growth factor and steroids after a failed trial of high-dose intravenous corticosteroids. Visual acuity improved to 20/25 at 3 weeks and remained stable at 9 months. Reports of full visual recovery are exceedingly rare following this functional endoscopic sinus surgery complication.

Artificial Ionospheric Modification (AIM) can occur through deliberate or incidental injections of aerosols, chemicals or radio (RF) signals into the ionosphere. The Metal Oxide Space Clouds (MOSC) experiment was undertaken in April/May 2013 to investigate chemical AIM. Two sounding rockets were launched from Kwajalein Atoll and each released a cloud of vaporized samarium (Sm). The samarium created a localized plasma cloud that formed an additional ionospheric layer. The effects were measured by a wide range of ground based instrumentation; this included a 17 channel direction finding chirp receiver. This system detected the new layer which remained visible to the HF sounder for approximately 25 minutes. The layer's maximum usable frequency peaked at approximately 10 MHz immediately after release. The direction to the reflection point remained constant at 355° whilst the new layer was visible to the sounder.

Low-frequency space-based synthetic aperture radar (SAR) can suffer from the degrading effects of a scintillating ionosphere, which modulates both the phase and amplitude of the radar signal. In this paper, we use the received signal from GNSS receivers to simulate the effect of the ionosphere on a point target. The process for transforming the one-way GNSS signal, which contains a variety of signal biases and geometric factors, is described. Data recorded on Ascension Island during scintillation events is then used to determine the peak to sidelobe ratio (PSLR) that would be obtained from a SAR. A phase correction is applied to one GNSS receiver using another located along a magnetic east-west baseline. It is shown that this improves the SAR point spread function (PSF) and the variation with baseline distance is illustrated. It is concluded that, up to a baseline distance of at least 2305 m, the phase correction improves the focus.

Rarely occurring solar superstorms generate X-rays and solar radio bursts, accelerate solar particles to relativistic velocities and cause major perturbations to the solar wind. These environmental changes can cause detrimental effects to the electricity grid, satellites, avionics, air passengers, signals from satellite navigation systems, mobile telephones and more. They have consequently been identified as a risk to the world economy and society. This paper will review their impact on a variety of engineered systems and will identify ways to prepare for these low-probability but randomly occurring events. Explosive eruptions of energy from the Sun that cause minor solar storms on Earth are relatively common events. In contrast, extremely large events (superstorms) occur very occasionally — perhaps once every century or two. Most superstorms miss the Earth, travelling harmlessly into space. Of those that do travel towards the Earth, only half interact with the Earth's environment and cause damage. Since the start of the space age, there has been no true solar superstorm and consequently our understanding is limited. There have, however, been a number of near misses and these have caused major technological damage, for example the 1989 collapse of part of the Canadian electricity grid. A superstorm which occurred in 1859, now referred to as the ‘Carrington event’ is the largest for which we have measurements; and even in this case the measurements are limited to perturbations of the geomagnetic field. An event in 1956 is the highest recorded for atmospheric radiation with August 1972, October 1989 and October 2003 the highest recorded radiation events measured on spacecraft. How often superstorms occur and whether the above are representative of the long term risk is not known and is the subject of important current research. The general consensus is that a solar superstorm is inevitable, a matter not of ‘if’ but ‘when?’. One contemporary view is that a Carrington-level event will occur within a period of 250 years with a confidence of ∼95% and within a period of 50 years with a confidence of ∼50%, but these figures should be interpreted with considerable care. Mitigation of solar superstorms necessitates a number of technology-specific approaches which boil down to engineering out as much risk as is reasonably possible, and then adopting operational strategies to deal with the residual risk. In order to achieve the latter, space and terrestrial sensors are required to monitor the storm progress from its early stages as enhanced activity on the Sun through to its impact on Earth. Forecasting a solar storm is a challenge, and contemporary techniques are unlikely to deliver actionable advice, but there are growing efforts to improve those techniques and test them against appropriate metrics. Irrespective of forecasting ability, space and terrestrial sensors of the Sun and the near space environment provide critical space situational awareness, an ability to undertake post-event analysis, and the infrastructure to improve our understanding of this environment. This paper will explore a number of technologies and demonstrate that global society and economies are indeed vulnerable to a solar superstorm. In a ‘perfect storm’ a number of technologies will be simultaneously affected which will substantially exacerbate the risk. Mitigating and maintaining an awareness of the individual and linked risks over the long term is a challenge for government, for asset owners and for managers.

A technique for neural network time series prediction using radial basis functions, where the input data contain a significant proportion of missing points, is developed. This technique is intended to model the data while simultaneously providing a means of minimizing the impact upon the model of the missing points that are typical of geophysical time series. The two issues are inextricably entwined because missing data points have a significant impact upon the performance of data-derived models in terms of prediction availability and accuracy. The core of the technique is a nonlinear interpolation scheme that assigns values to gaps in the input time series. Each missing point is interpolated such that the error introduced into any specific predictive function is minimized. This interpolative technique has a general application in any instance where the effects of interpolation upon a given analysis process need to be minimized or a complete time series needs to be constructed from incomplete data. The technique has been applied to the prediction of ƒ0F2 from Slough, United Kingdom. The resultant model prediction root-mean-square (RMS) error is shown to be 2.3% better than using recurrence interpolation (in terms of overall model accuracy rather than relative to each other), 3.8% better than using persistence interpolation, and 34.3% better than not using any interpolation. Utilizing the interpolation algorithm lowers the RMS error by 26% when incomplete data, in addition to complete data, are used as an input to both the interpolated and the uninterpolated models.

The high-latitude HF channel has been measured and characterized in terms of Doppler spread, delay spread, and signal-to-noise ratio. The performance of data modems has been determined over a comprehensive range of simulated channel conditions. A comparison is made between the channel measurements and the modem characterizations. Thereby the percentage of time that the modem works satisfactorily (availability), during the measured channel conditions, is determined. Two 75 bits/s modems (compliant with STANAG 4415 and STANAG 4285), a 2400 bits/s modem (compliant with STANAG 4285), Morse code, and voice have been selected for analysis. The two 75 bits/s modems show 60–75% higher availability than the 2400 bits/s modem on the measured paths. The 2400 bits/s modem is degraded in performance during a geomagnetic disturbance whereas the 75 bits/s modems maintain approximately the same performance level. The paper also addresses the necessary frequency pool (at a specific time) required for an HF circuit to achieve the best possible communications availability. For the 75 bits/s modems, independent of path length, a one-frequency pool is all that is required during summer and winter when the ionospheric conditions are quiet. A four frequency pool is necessary during disturbed ionospheric conditions. For the 2400 bits/s waveform, three to four frequencies are needed on the 200 km west-east path, and four to six frequencies are required on the north-south 2000 km path. This applies to all seasons and geomagnetic conditions analyzed.

During the total solar eclipse observed in Europe on August 11, 1999, measurements were made of the amplitude and phase of four VLF transmitters in the frequency range 16–24 kHz. Five receiver sites were set up, and significant variations in phase and amplitude are reported for 17 paths, more than any previously during an eclipse. Distances from transmitter to receiver ranged from 90 to 14,510 km, although the majority were 10,000 km. Negative phase changes were observed on most paths, independent of path length. Although there was significant variation from path to path, the typical changes observed were ∼3 dB and ∼50°. The changes observed were modeled using the Long Wave Propagation Capability waveguide code. Maximum eclipse effects occurred when the Wait inverse scale height parameter β was 0.5 km−1 and the effective ionospheric height parameter H′ was 79 km, compared with β=0.43 km−1 and H′=71 km for normal daytime conditions. The resulting changes in modeled amplitude and phase show good agreement with the majority of the observations. The modeling undertaken provides an interpretation of why previous estimates of height change during eclipses have shown such a range of values. A D region gas-chemistry model was compared with electron concentration estimates inferred from the observations made during the solar eclipse. Quiet-day H′ and β parameters were used to define the initial ionospheric profile. The gas-chemistry model was then driven only by eclipse-related solar radiation levels. The calculated electron concentration values at 77 km altitude throughout the period of the solar eclipse show good agreement with the values determined from observations at all times, which suggests that a linear variation in electron production rate with solar ionizing radiation is reasonable. At times of minimum electron concentration the chemical model predicts that the D region profile would be parameterized by the same β and H′ as the LWPC model values, and rocket profiles, during totality and can be considered a validation of the chemical processes defined within the model.

Purpose: In thyroid eye disease (TED), intraocular pressure (IOP) measurements are taken in both the primary and upgaze positions to elicit restrictive muscle disease. The aim of this study was to assess whether the IOP when measured with the eyes in upgaze (the Goldmann applanation tonometer [GAT] head applanating the inferior/peripheral cornea) is similar when compared with the central corneal IOP in upgaze using the Tono-Pen XL. Methods: IOP was measured with the GAT on the central cornea in primary gaze and on the inferior cornea in upgaze. IOP was measured with the Tono-Pen XL in the central cornea in both primary gaze and upgaze. The outcome measure was the difference in IOP readings between the GAT and the Tono-Pen XL for patients with restrictive TED. Results: Fifty-two patients were included in the study; 31 patients with restrictive TED and 21 control patients. In the control group, there was no significant difference in Tono-Pen XL and GAT readings for both primary gaze and upgaze (p = 0.99). Both instruments detected an increase in IOP with upgaze in patients with restrictive TED compared with controls (p = 0.0006). There was no significant difference between the 2 instruments' readings in upgaze for patients with restrictive TED (p = 0.39). Conclusions: Both the GAT and the Tono-Pen XL can be used to establish IOP in patients with restrictive TED.

An application of nonlinear radial basis function (RBF) neural networks (NNs) to improve the accuracy of the prediction of ionospheric parameters is presented. Principal component analysis is also adopted for the purposes of noise and dimension reduction. Hourly, daily, and monthly predictive models have been created for the Slough, England, United Kingdom, foF2 time series. The quality of the model predictions is evaluated by comparison with corresponding predictions from reference persistence or recurrence models. Each RBF NN offers a significant improvement over the performance of the corresponding reference model. The noonday model gives a performance improvement of ∼60% over the baseline persistence model, for a 1 day ahead prediction. For a 1 hour ahead prediction the hourly model offers an improvement of ∼45% over the baseline 24 hour recurrence model. Finally, the monthly median model gives a performance improvement of ∼40% over the baseline persistence model, for a 1 month ahead prediction.

This paper proposes a novel technique for the prediction of solar-terrestrial data sets that contain a significant proportion of missing data points. A nonlinear interpolation technique is employed to assign values to gaps in a time series. Each missing point is interpolated such that the error introduced into any specific predictive function is minimised. Radial Basis Function Neural Networks are adopted for the purpose of prediction, and their advantages over their Multi-Layer Perceptron counterparts are outlined. This technique has general application in any instance where the effects of interpolation upon a given analysis process need to be minimised or a complete time series needs to be constructed from incomplete data.

Using data from the Sweden and Britain Radar Experiment (SABRE) VHF coherent radar, Yeoman et al. [1990] found evidence for two and four sector structures during the declining phase of solar cycle (SC) 21. No such obvious harmonic features were present during the ascending phase of SC 22. It was suggested that the structure of the heliospheric current sheet might exhibit nonlinear behavior during the latter period. A direct test of this suggestion, using established nonlinear methods, would require the computation of the fractal dimension of the data, for example. However, the quality of the SABRE data is insufficient for this purpose. Therefore we have tried to answer a simpler question: Is there any evidence that the SABRE data was generated by a (low-dimensional) nonlinear process? If this were the case, it would be a powerful indicator of nonlinear behavior in the solar current sheet. Our approach has been to use a system of orthogonal linear filters to separate the data into linearly uncorrelated time series. We then look for nonlinear dynamical relationships between these time series, using radial basis function models (which can be thought of as a class of neural networks). The presence of such a relationship, indicated by the ability to model one filter output given another, would equate to the presence of nonlinear properties within the data. Using this technique, evidence is found for the presence of low-level nonlinear behavior during both phases of the solar cycle investigated in this study. The evidence for nonlinear behavior is stronger during the descending phase of SC 21. However, it is not possible to distinguish between nonlinear dynamics and a nonlinearly transformed colored Gaussian noise process in either instance, using the available data. Therefore, in conclusion, we find insufficient evidence within the SABRE data set to support the suggestion of increased nonlinear dynamical behavior during the ascending phase of SC 22. In fact, nonlinear dynamics would seem to exert very little influence within the measurement time series at all, given the observed data. Therefore it is likely that stochastic or unresolved high-dimensional nonlinear mechanisms are responsible for the observed spectrum complexity during the ascending phase of SC 22.

Analytic ray tracing is considerably less time consuming than numerical ray tracing. However, despite the advantage of speed, analytic ray tracing has a major limitation: the difficulty of including the effects on the ray path of horizontal gradients in electron density. In the past this difficulty has been addressed using ionospheric models whereby an effective tilt is introduced by displacing the center of the ionosphere from the center of the Earth. In this paper, ray equations for the ground range, phase path, group path, and divergent power loss are developed for a new two-dimensional analytic ray tracing technique, known as the segmented method for analytic ray tracing (SMART), which is able to deal with horizontal gradients in electron density. Ray tracing using two tilting methods are compared with ray tracing using SMART. Further, these results are compared with a numerical ray tracing program known as homing-in ray tracing (HIRT).

Measurements of Doppler spread, multipath spread, and signal-to-noise ratio have been made on four high-latitude high-frequency (HF) communications paths. The measurement system and analysis techniques are outlined, and an analysis of the data pertinent to the design of robust HF data modems is presented. A summary of the spreads that are exceeded for 5% of time is presented for each path. Doppler spreads range from 2 to 55 Hz, while multipath spreads range from 1 to 11 ms. Physical interpretations of the data are made, and the data are related to the measured performance characteristics of an HF data modem to estimate the modem availability on the paths considered. When there is mode support, availabilities range from 64% to 100% for a signal-to-noise ratio of 0 dB, although the data indicate that the availabilities can generally be increased by optimizing frequency selection.

A computer model to predict the underdense meteor arrival rate over a forward meteor scatter communications link is presented. The model incorporates important effects such as major shower streams, a nonuniform radiant distribution, and antenna polarization coupling. A particularly useful aspect of the model is its capacity to predict the passage of sporadic and shower hotspot regions across the sky and thereby provide directional information to drive an adaptive beam steering system. Directional data from a phased array reception system in the United Kingdom has been used to determine the diurnal arrival distribution of sporadic meteors. This diurnal variation is broadly reproduced by the model and suggests that just two daily changes in the direction of a high-gain beam would offer considerable advantage over a fixed beam system. This paper shows that further improvements in system performance can be achieved with accurate predictions of the time of appearance and location of shower streams. A comparative study between monthly predictions and experimental data from a high-latitude link in Greenland over a year shows reasonable agreement but highlights the need for higher-resolution radiant data.

A new two-dimensional analytic ray tracing method, known as segmented method for analytic ray tracing (SMART), which automatically segments the ionosphere along the ray path is described. Unlike other techniques, SMART is able to accurately ray trace through horizontal gradients which vary with altitude along and in the direction of the ray path. Computer run times are approximately 10 times faster than those of numerical ray tracing packages, and ground range errors are typically less than 2.5%.

We have analyzed the duty cycle, due to ionospheric propagation, of very high frequency sounding signals for both polar cap and auroral paths. We find that at 35 and 45 MHz the propagation is often sustained by sporadic E layers and other nonmeteoric modes rather than by meteor scatter. At the higher frequencies of 65 and 85 MHz we find that the path is generally dominated by meteor scatter modes. These results have important ramifications for frequency reuse and security in meteor burst communications systems and for the development of extended frequency range HF systems (above 30 MHz) with a capability to operate on any available propagation mode. The diurnal, seasonal, and geomagnetic variations of the nonmeteoric duty cycle have been examined. A polar cap path model is presented for the nonmeteoric duty cycle as a function of geomagnetic activity.