Contact lens-related complications in austere conditions among military personnel: a systematic review.

INTRODUCTION: Military service personnel are required to deploy to austere environments where they are exposed to harsh conditions. Many service personnel continue to wear contact lenses when deployed as they are an effective alternative to spectacles by affording superior ergonomic functionality, although they are associated with significant complications. We aimed to explore the prevalence and type of contact lens-related complications among deployed service personnel worldwide. METHODS: A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 statement. PubMed, Medline, CINAHL and EMBASE databases were searched for relevant articles published between 1950 and 2023. The keywords 'contact lens' and 'military' or 'army' or 'navy' or 'air force' and 'austere' or 'deployed' or 'adverse' were used. RESULTS: Five eligible articles were included. Excluded articles reported contact lens wear in the firm base, were not related to military personnel or did not involve the deployed setting. Major complications associated with contact lens wear included microbial keratitis and contact lens-related discomfort. Excluding case reports, the overall incidence of contact lens-related complications ranged from 0.35% to 25.4%. The three case reports included in this systematic review described Acanthamoeba keratitis, Nocardia keratitis and contact lens-related discomfort as significant complications. These case reports also detailed time to initial presentation and type of contact lens worn when complications were encountered. Types of deployed conditions service personnel were exposed to included desert, temperate and underwater environments. CONCLUSIONS: We highlight a scarcity of recent data regarding contact lens-related complications in the deployed setting. While contact lens-wearing service personnel are at risk of infectious keratitis and contact lens-related discomfort, we recommend good-quality data collection on contact lens wearing schedules and complication rates to steer guidance on contact lens wear in service personnel.

Retinal blood flow in critical illness and systemic disease: a review.

BACKGROUND: Assessment and maintenance of end-organ perfusion are key to resuscitation in critical illness, although there are limited direct methods or proxy measures to assess cerebral perfusion. Novel non-invasive methods of monitoring microcirculation in critically ill patients offer the potential for real-time updates to improve patient outcomes. MAIN BODY: Parallel mechanisms autoregulate retinal and cerebral microcirculation to maintain blood flow to meet metabolic demands across a range of perfusion pressures. Cerebral blood flow (CBF) is reduced and autoregulation impaired in sepsis, but current methods to image CBF do not reproducibly assess the microcirculation. Peripheral microcirculatory blood flow may be imaged in sublingual and conjunctival mucosa and is impaired in sepsis. Retinal microcirculation can be directly imaged by optical coherence tomography angiography (OCTA) during perfusion-deficit states such as sepsis, and other systemic haemodynamic disturbances such as acute coronary syndrome, and systemic inflammatory conditions such as inflammatory bowel disease. CONCLUSION: Monitoring microcirculatory flow offers the potential to enhance monitoring in the care of critically ill patients, and imaging retinal blood flow during critical illness offers a potential biomarker for cerebral microcirculatory perfusion.

Detection of Papilloedema Study (DOPS): rates of false positive papilloedema in the community.

BACKGROUND: Overdiagnosis of papilloedema is common and carries significant potential for morbidity from over-investigation and over-treatment. We aimed to determine the community prevalence of false positive diagnosis of papilloedema (FPE) on fundus imaging. METHODS: We evaluated fundus images from a community cross-section of 198 12-14-year-olds from the Avon Longitudinal Study of Parents and Children (ALSPAC) longitudinal cohort study database and patient images from our hospital departmental database with and without papilloedema. We asked clinicians, in isolation, to rate the subjects as a forced choice task to "papilloedema" or "not papilloedema" based on the fundus images alone. Raters comprised (i) four neuro-ophthalmologists, (ii) four ophthalmologists, (iii) four neurologists and (iv) four emergency medicine physicians. RESULTS: The prevalence of FPE in the ALSPAC population, defined as images mistaken as papilloedema by χ% of raters (Pχ) varied from P100 = 0% to P50 = 21.3 ± 3.9%. In the hospital population, there was a lower rate of FPE, P50 = 7.1 ± 10.8%. Sensitivity for papilloedema detection approached 100%, though three raters incorrectly labelled the same patient with unilateral disc swelling as normal, all other cases were detected by all raters. CONCLUSIONS: Fundus photography assessment in isolation is highly sensitive but poorly specific for papilloedema detection. Using this method to screen the general population has significant potential for harm as overdiagnosis occurs, even in the hands of experienced clinicians.

Differing presenting features of idiopathic intracranial hypertension in the UK and US.

AIM: Demographic factors potentially influencing the presentation and severity of idiopathic intracranial hypertension (IIH) in the US vs. UK populations include obesity and ethnicity. We aimed to compare the presenting features of IIH between populations in the UK and US tertiary referral centres, to assess what population differences exist and whether these cause different presentations and impact on visual function. METHODS: Clinical data were collected on 243 consecutive UK IIH patients and 469 consecutive US IIH patients seen after 2012 in two tertiary centres. Visual function was defined as severe visual loss when Humphrey visual field mean deviation was <-15 dB, when Goldmann visual fields showed constriction or when visual acuity was <20/200. RESULTS: US patients were more commonly of self-reported black race (58.9% vs. 7.1%) than UK patients, but had a similar mean body mass index (38.3 ± 0.63kg/m2 UK vs. 37.7 ± 0.42kg/m2 US; p = 0.626). The UK cohort had lower presenting Frisén grade (median 1 vs. 2; p < 0.001) and severe visual loss less frequently (15.4% vs. 5%; p = 0.014), but there was no difference in mean cerebrospinal fluid-opening pressure (CSF-OP) (35.8 ± 0.88cmH2O UK vs. 36.3 ± 0.52cmH2O US; p = 0.582). African Americans had poorer visual outcomes compared with US whites (19.4% vs. 10% severe visual loss; p = 0.011). Visual function was weakly associated with CSF-OP (R2 = 0.059; p = 0.001), which was similar between UK and US patients. CONCLUSIONS: The UK and the US cohorts had a similar average presenting BMI. However, the worse presenting visual function in the US IIH cohort was partially attributable to differences in the black populations in the two countries.

Ophthalmic injuries in British Armed Forces in Iraq and Afghanistan.

AIM: British military ophthalmologists have not been deployed in support of operations since 2003. Eye injuries in British forces receive definitive treatment on return to the United Kingdom. We report the injury patterns, management strategies, and outcomes for eye injuries in British Armed Forces in Iraq and Afghanistan. METHODS: Retrospective consecutive case series of eye injuries in British Armed Forces in Iraq or Afghanistan from July 2004 to May 2008. Outcomes assessed by final best-corrected visual acuity (VA; few patients lost to follow-up), rates of endophthalmitis, and proliferative vitreoretinopathy (PVR). RESULTS: There were 630 cases of major trauma, 63 sustained eye injuries (10%), and 48 sustained significant eye injuries. There were 21 open-globe injuries: 9 ruptures and perforating injuries, of which 7 were enucleated/eviscerated; 11 intraocular foreign body (IOFB) injuries, of which 1 was eviscerated. Primary repair was combined with posterior segment reconstruction in 9/11 cases with IOFB. Mean time to primary repair was 1.9 days (range 0-5). Intravitreal antibiotics were given at primary repair in five cases. All cases received early broad-spectrum systemic antibiotics. Median final VA was logMAR 0.25 excluding evisceration/enucleations. There were two cases of PVR and none of endophthalmitis. CONCLUSIONS: The number of eye injuries as a proportion of all casualties is lower than recently reported. The injuries are more severe than in civilian practise. The outcomes were comparable with previous reports, this demonstrates that, in certain cases, primary repair can be safely delayed beyond 24 h in the patient's best interests, in order to optimise the conditions for treatment.

A case of external ophthalmomyiasis in a deployed U.K. soldier.

Infestation of the eye by larval fly forms (ophthalmomyiasis) is rarely seen in the Western world. We present the case of a 21 year old British soldier who developed external ophthalmomyiasis during an operational tour of southern Afghanistan. This case report and discussion illustrates the potential for ophthalmomyiasis in personnel deployed to this theatre; the possibility of infestation without an identifiable episode of exposure; the importance of proper assessment and follow-up in order to identify sight-threatening complications; and the balance between optimal patient care and the risks inherent to casualty evacuation demanded by modern day stability operations.

Controlling factors in the synthesis of cucurbituril and its homologues.

The acid-catalyzed synthesis of cucurbit[n]urils from formaldehyde and glycoluril is poorly understood. In this paper, we examine a wide range of reaction conditions that include the effects of acid type, acid concentration, reactant concentrations, and temperature to both probe the mechanism and optimize the yields of isolated cucurbit[n]urils, where n = 5-10. A mechanism for the formation of these cucurbit[n]urils is presented. Individual cucurbit[n]urils were unambiguously identified in reaction mixtures using ESMS and (13)C NMR.