Severe ocular chemical injury in the UK: a British Ophthalmological Surveillance Unit study.

BACKGROUND: Severe ocular chemical injury is a potentially devastating condition which most commonly affects men of working age. Workplace injuries previously accounted for the majority of incidents, but there has been a recent increase in assaults involving corrosive substances throughout the UK. The objectives of this study were to determine the incidence and demographics of severe ocular chemical injury and describe current surgical management practices. METHODS: Cases were prospectively ascertained through the British Ophthalmological Surveillance Unit monthly reporting system during 2019-21. In total, 20 cases involving 29 eyes met the inclusion criteria. RESULTS: The reported incidence of severe ocular chemical injury during the pre-pandemic period of the study was 0.24 per million. Cases due to alleged assault have become more common than workplace injuries. A total of 81% patients had persistent complications at 6 months requiring ongoing treatment, and 60% patients required surgical intervention. CONCLUSION: Although there are limitations with the case ascertainment methods, severe ocular chemical injury remains rare within the UK. There has been a proportionate increase in cases related to alleged assault compared with previous similar studies. Amniotic membrane grafting remains the most commonly performed surgical procedure in these patients.

Incidence of Acanthamoeba Keratitis in the United Kingdom in 2015: A Prospective National Survey.

PURPOSE: The aims of this study were to quantify the incidence of Acanthamoeba keratitis (AK) in the United Kingdom and investigate risk factors and management parameters. METHODS: This was a prospective population-based study from January to December 2015 through the British Ophthalmic Surveillance Unit. Data were collected on demographics, clinical features, and management. Incidence rates were calculated from estimates of population and contact lens (CL) user numbers. Statistical analysis compared annualized incidences per million and altered risk ratios for AK with the England and Wales 24 months 1997/1998 to 1998/1999 study. RESULTS: The study identified 124 AK cases, an overall incidence of 2.35 per million. CL wearers accounted for 108 of 124 cases (87%), in whom the AK incidence was 26.94 per million. Herpes keratitis was initially misdiagnosed in 25 of 124 cases (20.2%). The highest incidence of AK was among planned replacement soft CL (PRSCL) wearers (50.65 per million), 7-fold greater than for daily disposable CL (DDSCL) users (7.24 per million). There was a significant increase in AK incidence ( P < 0.001) compared with both 1997/1998 [risk ratio 1.92, 95% confidence interval (CI) 1.38-2.66] and 1998/1999 (risk ratio 2.13, 95% CI 1.52-2.98) together with a higher incidence per million CL users of 26.94 versus 21.14 (1997/1998) and 17.53 (1998/1999). CONCLUSIONS: This study provides the first published data on the nationwide incidence of AK in the United Kingdom. The findings confirm an increasing incidence of AK, particularly among contact lens wearers since 1997/1998 to 1998/1999. PRSCLs were identified as a significant risk factor compared with DDSCLs. Misdiagnosis and treatment delays remain an ongoing problem for patients with AK.

Estimating the rate of severe visual loss (wipe-out) following cataract surgery, a British Ophthalmological Surveillance Unit (BOSU) study.

BACKGROUND: A sudden, irreversible reduction in visual acuity ('wipe-out') is a feared complication of cataract surgery. Current literature on wipe-out is limited in quantity and quality, and largely predates modern cataract surgery and imaging techniques. The objectives of our study were to estimate the incidence of wipe-out and to identify potential risk factors. METHODS: We prospectively collated cases of wipe-out occurring in the UK during a 25-month study period using the British Ophthalmic Surveillance Unit reporting system. A total of 21 potential cases of wipe-out were reported, 5 of which met all inclusion and exclusion criteria. RESULTS: The estimated incidence of wipe-out during the study period was 0.00000298, or approximately 3 cases per million cataract operations. All cases of wipe-out occurred exclusively in patients with advanced glaucoma (mean deviation -21.0 decibels or worse in the operated eye), with an over-representation of black people (40%) in our case series. A prior diagnosis of retinal vein occlusion (60%) and elevated post-operative IOP (40%) were more common among individuals suffering from wipe-out compared to the general population, suggesting these factors may contribute to the pathogenesis of wipe-out. CONCLUSIONS: Our study shows that wipe-out is a rare complication, affecting approximately 3 per million undergoing cataract surgery. Patients with advanced glaucoma, black patients, and those with previous retinal vein occlusions may be at greater risk of wipe-out. We hope that the findings of our study will be used to help inform treatment decision-making and the cataract surgery consent process.

Incidence of ophthalmic involvement in Behçet's disease in the United Kingdom: a British Ophthalmic Surveillance Unit (BOSU) study.

BACKGROUND: Behçet's disease (BD) is a relapsing-remitting vasculitis, which can manifest in different organ systems including the eyes. There is currently limited published data describing the incidence of ophthalmic disease within the United Kingdom. The primary aim of this study was to survey the incidence and manifestations of ophthalmic BD prospectively, with a secondary aim of reviewing treatment modalities initiated in first-line therapy. METHODS: Using the British Ophthalmic Surveillance Unit reporting system between October 2016 and November 2018, we prospectively surveyed the number of cases of BD presenting to UK ophthalmologists. A total of 89 cases of ophthalmic manifestations of BD were reported and complete information was collected on 58 patients. RESULTS: 93 eyes of 58 patients were affected. The median age of reported cases was 31 years (range 13-55 years) who were born in 15 different countries. Most cases (n = 35, 60%) had bilateral involvement. Vitritis was the most common ocular manifestation (68%; n = 63) followed by anterior uveitis (46%; n = 43). The greatest causes of visual morbidity were cystoid macular oedema, vitritis and retinal ischaemia. Most patients were prescribed either topical or oral corticosteroids (59%; n = 34), with some given intravitreal or intravenous corticosteroids. Five patients (8.6%) were initiated on disease-modifying anti-rheumatic drugs and one given an anti-TNF monoclonal antibody. CONCLUSIONS: This is the first prospective study to analyse the incidence of ophthalmic involvement in BD over a 2-year period, finding an annual incidence of 0.04 per 100,000 individuals in the UK.

A prospective, population-based, surveillance (BOSU) study of uveal effusion syndrome in the UK.

PURPOSE: To determine the incidence and demographic profile of uveal effusion syndrome (UES), and to describe the visual and anatomic outcome following deep sclerectomy or vortex vein decompression. METHODS: The British Ophthalmological Surveillance Unit (BOSU) mails reporting cards monthly to 1149 senior UK ophthalmologists, who are requested to report incident cases of specified rare diseases. UES was included in the reporting system from October 2009 to October 2011. If UES was identified, ophthalmologists were mailed a questionnaire to collect anonymized clinical data at baseline, and 12 months after. RESULTS: Over 2 years, 29 cases were reported. Two cases were duplicates and 12 failed to meet the eligibility criteria. Of the 15 eligible cases, age ranged from 11 to 91 years (mean 62) and nine were males (60%). Ten patients were hypermetropic; three had an axial length of 19.0 mm or less. Estimated annual incidence was 1.2 per 10 million population. Seven cases were managed nonsurgically, including observation (one case), topical steroids (two cases), systemic steroids (three cases), and cyclodiode laser (one case). Eight cases (11 eyes) underwent full-thickness sclerectomy; the elevated flap was retained in four. The sclera was noted to be thick and rigid during surgery in five cases. Median preoperative visual acuity was 6/18, changing slightly to 6/21.5 at final review, with three eyes showing complete anatomic response, five showing some improvement, and three failing to respond. CONCLUSIONS: UES is extremely rare. It occurs in a range of ages, but is most common in middle-aged, hypermetropic men. Visual acuity can be materially reduced. The most commonly used surgical treatment in the UK is deep sclerectomy.

Childhood uveitis not associated with juvenile idiopathic arthritis: a national survey of incidence, management and visual outcomes.

AIMS: To estimate the incidence of childhood uveitis not associated with juvenile idiopathic arthritis (JIA) in the United Kingdom. METHODS: Children under 16 years who presented with a new diagnosis of uveitis from November 2014 to October 2015 were identified prospectively through the British and Scottish Ophthalmological Surveillance Unit reporting card system. Incident questionnaires were sent to reporting ophthalmologists at presentation and 12 months. RESULTS: From 1st November 2014 to 31st October 2015, 119 cases were reported. Thirty-nine cases were excluded. The estimated minimum annual incidence of non-JIA uveitis in children younger than 16 years is 0.66 per 100,000 (95% CI 0.52-0.82). Median age at presentation was 10 years. 73% had bilateral uveitis. Median (IQR) BCVA in the worse eye was 0.3 (IQR 0.1-0.66) logMAR. The location of uveitis was: anterior 36%, intermediate 24%, posterior 6.8% and panuveitis 30%. 70% of cases were idiopathic. Most children were started on topical corticosteroids at presentation (86%, n = 51). At presentation, 31% (n = 19) were on started on systemic corticosteroids. At 1 year only 13% (n = 7) remained on corticosteroids, with the majority transitioned to steroid-sparing agents: methotrexate (30.8%, n = 16), mycophenolate (5.8%) and anti-TNF agents 5 (9.6%). At 1 year, 46% had ongoing intraocular inflammation despite treatment. The most common ocular adverse event was raised intraocular pressure (13.5%, n = 7). CONCLUSION: Our study provides the first national population-based data of non-JIA childhood uveitis. Most children remain on treatment at 1 year, but visual acuity improves and none were eligible for sight-impairment registration.

The incidence and management of persistent cystoid macular oedema following uncomplicated cataract surgery-a Scottish Ophthalmological Surveillance Unit study.

PURPOSE: Post-operative cystoid macular oedema (CMO) can cause deterioration of vision following routine cataract surgery. The incidence of persistent CMO (pCMO; defined as CMO present after 3 months) following uncomplicated surgery is uncertain. We wished to identify the incidence, management and visual outcomes of such patients. METHODS: A Scottish Ophthalmological Surveillance Unit (SOSU) questionnaire was sent monthly to every ophthalmic specialist in Scotland over an 18-month period from 1st January 2018 asking them to report all new patients with pCMO confirmed on OCT scanning following uncomplicated cataract surgery. A follow-up questionnaire was sent 9 months after initial presentation. RESULTS: Fourteen cases of pCMO were reported, giving an incidence of 2.2 cases of pCMO per 10,000 uncomplicated cataract surgeries. Mean age was 74.9 years (SD 10.2; range 44-86) with a male preponderance (72.7%). Two patients developed pCMO in each eye. Six cases (46.2%) had hypertension and one had diabetes. Three eyes required intracameral adjuncts (two iris hooks, one intracameral phenylephrine). Postoperative visual acuity (VA) at 3 months was logMAR 0.48 (0.2-0.8). Average mean central retinal thickness (CRT) at 3 months was 497microns (270-788). The most common initial treatment comprised topical steroids and topical NSAIDs (61.5%). Other management strategies included systemic steroids, intravitreal steroids and oral acetazolamide. At 1-year post-op, mean VA was logMAR 0.18 (0.1-0.3) with average mean CRT of 327microns (245-488). CONCLUSIONS: We identified a low incidence of pCMO following uncomplicated cataract surgery in Scotland (0.02%), with inconsistent and variable management regimes. A nationally agreed treatment protocol is required.

Presumed ocular tuberculosis in the United Kingdom: a British Ophthalmological Surveillance Unit (BOSU) study.

INTRODUCTION: Ocular tuberculosis (TB) is an extrapulmonary manifestation of mycobacterium infection that most commonly presents as uveitis. This is the first prospective incidence study of presumed ocular tuberculosis performed in the United Kingdom (UK). METHOD: New cases of ocular tuberculosis presenting to hospitals in the UK were prospectively ascertained between October 2016 and November 2017 with the aid of the British Ophthalmological Surveillance Unit (BOSU). Initial presentation data and 1-year follow-up data was collected using questionnaires. RESULTS: Forty-eight patients were recruited giving an overall incidence for ocular TB of 0.73 per million population per annum. The origin of birth for 71% of the patients was a non-UK country and 87.5% had their initial diagnosis of TB made by an ophthalmologist. The most common first line treatment was isoniazid, rifampicin, ethambutol and pyrazinamide which 71% of patients were treated with 60% of patients were commenced on a reducing course of oral steroids. At 1-year follow-up, 29 patients (83%) had complete resolution of active clinical signs. Mean best corrected visual acuity (BCVA) at presentation was +0.41 LogMAR(SD = 0.62), compared to +0.31 LogMAR (SD = 0.56) at 12-month follow-up. DISCUSSION: It is increasingly the responsibility of the ophthalmologist to diagnose ocular TB and although it remains a rare condition, consensus on diagnostic criteria and treatment is required. Increasing recognition and accessibility to gamma-interferon testing should enable earlier detection. Treatment with quadruple ATT treatment regimens for at least 6 months shows good clinical outcomes. However, it is still unclear whether steroid use is beneficial. Further large studies with longer follow-up would be warranted to answer these questions.

The incidence of idiopathic intracranial hypertension in Scotland: a SOSU study.

BACKGROUND: Idiopathic intracranial hypertension most commonly affects women of childbearing age and usually causes headache and intermittent visual obscurations. Some patients suffer permanent visual loss. The major modifiable risk factor associated with IIH is obesity. Scotland has one of the poorest records for obesity in the western world, with a prevalence in 2016 of 29% in the adult population. We aimed to establish the incidence of idiopathic intracranial hypertension (IIH) in Scotland. METHODS: All new cases of IIH seen in Scotland were collected over a 1-year period. Cases were reported by ophthalmologists through the Scottish Ophthalmic Surveillance Unit (SOSU) and by neurologists directly to the investigators using encrypted NHS emails. An open dialogue was maintained between the investigators and specialist neuro-ophthalmology clinics throughout the year to minimise the risk of under-reporting. Cases were defined using the Modified Dandy Diagnostic Criteria. RESULTS: One hundred and forty-four confirmed cases of IIH were reported. One hundred and ten out of 144 patients were female and aged 15-44. The mean BMI in this group was 38.9. CONCLUSIONS: The incidence of IIH in Scotland is at least 2.65/100,000. This figure rises to 37.9/100,000 in obese females aged 15-44. This figure is higher than previously published and is probably a result of increasing levels of obesity across the nation. The significant morbidity caused by IIH, in this young population raises the question of whether enough is being done to prevent and treat Scotland's obesity crisis.

A British Ophthalmological Surveillance Unit (BOSU) study into dysthyroid optic neuropathy in the United Kingdom.

This prospective British Ophthalmological Surveillance Unit (BOSU) study on dysthyroid optic neuropathy (DON) determines the incidence, presenting features and management throughout the UK. New cases were identified through the BOSU yellow card and an initial questionnaire and a subsequent 9-month follow-up questionnaire were posted out. From August 2015 to August 2016 DON was reported in 49 patients with 71 eyes affected, 22 patients had bilateral DON. The most common presenting symptom was blurred vision (83%) and the most common examination finding was upgaze restriction (85%). 85% of patients were initially treated with 3 days of either 1 g or 500 mg intravenous methyl prednisolone. We received 25 follow-up questionnaires (51% of the initial cohort) with 38 eyes treated for DON and 13 bilateral cases. The average steroid dose over 9 months was 4.5 g and 47% of patients had a surgical orbital decompression. The mean visual acuity gain after 9 months of follow-up for all patients was 0.25 LogMAR. The mean visual acuity gain after just medical therapy was 0.25 LogMAR and after both medical therapy and orbital decompression it was 0.24 LogMAR. In conclusion, the incidence of DON in the UK from this study is 0.75 per million population per annum. The majority of patients are treated with initial medical therapy and almost half of all patients subsequently went on to have an orbital decompression. With either medical therapy or medical and surgical therapy, vision can improve in patients with DON.

The incidence of acute angle closure in Scotland: a prospective surveillance study.

PURPOSE: To estimate the incidence, and describe the clinical features and short-term clinical outcomes of acute angle closure (AAC). METHODS: Patients with newly diagnosed AAC were identified prospectively over a 12-month period (November 2011 to October 2012) by active surveillance through the Scottish Ophthalmic Surveillance Unit reporting system. Data were collected at case identification and at 6 months follow-up. RESULTS: There were 114 cases (108 patients) reported, giving an annual incidence of 2.2 cases (95% CI 1.8 to 2.6) or 2 patients (95% CI 1.7 to 2.4) per 1 00 000 in the whole population in Scotland. Precipitating factors were identified in 40% of cases. Almost one in five cases was associated with topical dilating drops. Best-corrected visual acuity (BCVA) at presentation ranged from 6/6 to perception of light. The mean presenting intraocular pressure (IOP) was 52 mm Hg (SD 11). Almost 30% cases had a delayed presentation of 3 or more days. At 6 months follow-up, 75% had BCVA of 6/12 or better and 30% were found to have glaucoma at follow-up. Delayed presentation (≥3 days) was associated with higher rate of glaucoma at follow-up (22.6% vs 60.8%, p<0.001), worse VA (0.34 vs 0.74 LogMAR, p<0.0001) and need for more topical medication (0.52 vs 1.2, p=0.003) to control IOP. CONCLUSION: The incidence of AAC in Scotland is relatively low compared with the Far East countries, but in line with previous European data. Almost one in five cases were associated with pupil dilation for retinal examination.

Corneal perforation from peripheral ulcerative keratopathy in patients with rheumatoid arthritis: epidemiological findings of the British Ophthalmological Surveillance Unit.

BACKGROUND/AIMS: This study quantifies the threat to vision and the survival in patients presenting with peripheral ulcerative keratopathy (PUK) corneal perforation associated with rheumatoid arthritis (RA) in the UK. METHODS: New cases of corneal perforation from PUK in patients with RA were prospectively collected from the UK via the British Ophthalmological Surveillance Unit from July 2012 to June 2014. An initial questionnaire collected data on presentation and the first 2 weeks' management, and a follow-up questionnaire collected 1-year data on ocular morbidity and mortality. RESULTS: 30 eyes of 28 patients were identified over 2 years, estimating a UK incidence of 0.234/million/year. 20/27 (74%) were female, with a median age of 68 years (range 41-84). The most common initial management was cyanoacrylate glue with a bandage contact lens, oral steroids, topical and oral antibiotics, and lubricants. Long-term management included corneal grafting in 12/20 (60%) eyes of patients living at 1 year. The 1-year all-cause mortality was 6/25 (24%), which increased to 1/2 (50%) if both eyes had perforated. In the remaining patients alive at 1-year follow-up, there was a 13/20 (65%) poor visual outcome of less than or equal to counting fingers. 8/25 (40%) patients had bilateral PUK, with 2/25 (8%) having bilateral perforation. 5/19 (26%) patients alive at 1-year follow-up were eligible for sight impairment registration. CONCLUSION: This study highlights the serious ocular morbidity and high mortality associated with corneal perforation from PUK in patients with RA despite treatment. The mortality doubled if both eyes perforated, which should serve as a harbinger of impending serious medical problems.

Case-control study of risk factors for acute corneal hydrops in keratoconus.

PURPOSE: To determine risk factors for the development of acute corneal hydrops in keratoconus in the UK in a case-controlled study. METHODS: Between November 2009 and December 2010, we prospectively identified 73 individuals who developed acute corneal hydrops. We then identified 174 controls from nine regions in the UK with keratoconus who had not had hydrops. For cases and controls we recorded demographics and clinical features. Univariate and multivariable logistic regressions were performed to identify risk factors. RESULTS: Univariate analysis suggested strong associations between the odds of hydrops and each of vernal keratoconjunctivitis (OR 4.08, 95% CI 1.45 to 11.49, p=0.008), asthma (OR 2.70, CI 1.34 to 5.47, p=0.006), atopic dermatitis (OR 3.13, CI 1.50 to 6.56, p=0.002), learning difficulties (OR 7.84, CI 2.86 to 21.46, p<0.001), previous hydrops (OR 40.2; CI 6.2 to ∞, p<0.001), black ethnicity (OR 2.98, CI 0.98 to 8.99; p=0.05), visual acuity in the worse eye (OR 8.76 CI 3.86 to 19.88; p<0.001) and minimum keratometry of ≥48 D prior to the hydrops (OR 4.91, CI 1.07 to 22.6, p=0.041). The use of a contact lens correction was also found to be associated with the odds of hydrops (OR 0.08; CI 0.03 to 0.19, p<0.001). Multiple variable regression indicated that having vernal keratoconjunctivitis (adjusted OR (AOR) 15, 95% CI 1.30 to 173.7; p=0.03), asthma (AOR 4.92, CI 1.22 to 19.78; p=0.025), visual acuity in worse eye (AOR 4.11, CI 1.18 to 14.32; p=0.026) and a high keratometry value (AOR 4.44, CI 0.85 to 23.18; p=0.077) were independently associated with the odds of hydrops in subjects with keratoconus. CONCLUSION: Some individuals with keratoconus are at high risk of developing acute corneal hydrops. These patients could be managed more aggressively to reduce their risk of developing this complication of their disease.

Observational prospective cohort study of patients with newly-diagnosed ocular sebaceous carcinoma.

PURPOSE: To investigate the epidemiology and clinicopathological management for ocular sebaceous carcinoma (OSC) in the UK. METHODS: Observational prospective cohort study of patients with newly-diagnosed OSC. The British Ophthalmological Surveillance Unit captured incident cases of OSC between 2008 and 2010. Incident and 6-month follow-up questionnaires from reporting ophthalmologists captured OSC demographic and clinical data. RESULTS: Data were available on 51 patients with unilateral OSC (response rate 85%). The UK estimated annual incidence was 0.41 cases per million population (95% CI 0.31 to 0.54). Median age was 70 years (SD 14, range 28-98) with 57% women. OSC location was upper lid (54%), lower lid (20%), multicentric (14%) and caruncle (12%). Most common misdiagnoses included chalazion (42%), basal cell carcinoma (30%) and blepharoconjunctivitis (16%), with median delay in diagnosis of 10 months (SD 9, range 0.5-36). Specialist ophthalmic pathologists performed diagnostics in 62%, with pagetoid/intraepithelial spread present in 39%. Misdiagnosis of chalazion (p=0.019) and pagetoid tumour spread (p=0.016) was associated with a significant diagnostic delay (one-way ANOVA/R(2)). Primary surgical management involved excision with reconstruction (49%), primary exenteration (10%) and Mohs surgery (8%). There were three deaths (out of 51) during the study period; one patient died of OSC-related disease and the other two due to other causes. CONCLUSIONS: This population-based prospective study confirms OSC as a rare cancer in the UK. Masquerade syndromes result in significant diagnostic delays and increase the risk of pagetoid tumour spread. There is considerable UK variation in pathological and surgical management, and ocular reconstruction and radical surgery is often required for OSC due to delayed presentation.

Posterior capsule rupture rate with akinetic and kinetic block anesthetic techniques.

A systematic literature search was performed to identify prospective randomized studies comparing akinetic (sub-Tenon, peribulbar, or retrobulbar) and kinetic (topical or topical and intracameral) local anesthesia for phacoemulsification surgery. Only studies that stated the rate of posterior capsule rupture or that stated without qualification that there were no intraoperative complications were included. Of the initial 3182 articles, 15 papers met the inclusion criteria. The number of eyes ranged between 26 and 282 per group (mean 95.4 eyes per group), with a total of 2862 eyes. Eleven articles mentioned posterior capsule rupture specifically; 4 stated that no intraoperative complications occurred. Eleven (0.74%) of 1494 eyes in the akinetic group and 11 (0.80%) of 1368 eyes in the kinetic group experienced posterior capsule rupture. The chi-square test confirmed the difference was not statistically significant (P = .84). This analysis indicates that there appears to be no clinically or statistically significant difference in the risk for posterior capsule rupture between akinetic and kinetic local anesthesia techniques.

Trends in provision of photodynamic therapy and clinician attitudes: a tracker survey of a new health technology.

BACKGROUND: There has been debate about the cost-effectiveness of photodynamic therapy (PDT), a treatment for neovascular age-related macular degeneration. We have been monitoring trends for the provision of PDT in the UK National Health Service. The fourth annual 'tracker' survey took place as definitive National Institute for Clinical Excellence (NICE) guidance was issued. We assessed trends in PDT provision up to the point of release of the NICE guidance and identified likely sources of pressure on ophthalmologists to provide PDT. METHODS: National postal questionnaire survey of clinicians with potential responsibility for PDT provision. The survey explored reported local provision, beliefs about the effectiveness of PDT and what sources of opinion might influence attitudes towards providing PDT. RESULTS: The response rate was 73% (111/150). Almost half of the surveyed ophthalmology units routinely provided PDT, as part of a trend of steady growth in provision. The proportion of respondents who believed that further proof of effectiveness was required has also declined despite the absence of any new substantial evidence. Attitudes towards providing PDT were positive, on average, and were more strongly associated with perceived social pressure from local colleagues than from other sources. Local colleagues were seen as being most approving of PDT. CONCLUSION: Those responsible for implementing the NICE guidance need to address ophthalmologists' beliefs about the evidence of effectiveness for PDT and draw upon supportive local individuals or networks to enhance the credibility of the guidance.