Healthcare worker protection against epidemic viral respiratory disease.

Lower respiratory infections are often caused or precipitated by viruses and are a leading cause of global morbidity and mortality. Mutations in these viral genomes can produce highly infectious strains that transmit across species and have the potential to initiate epidemic, or pandemic, human viral respiratory disease. Transmission between humans primarily occurs via the airborne route and is accelerated by our increasingly interconnected and globalised society. To this date, there have been four major human viral respiratory outbreaks in the 21st century. Healthcare workers (HCWs) are at particular risk during respiratory epidemics or pandemics. This is due to crowded working environments where social distancing, or wearing respiratory personal protective equipment for prolonged periods, might prove difficult, or performing medical procedures that increase exposure to virus-laden aerosols, or bodily fluids. This review aims to summarise the evidence and approaches to occupational risk and protection of HCWs during epidemic or pandemic respiratory viral disease.

Three-dimensional reconstruction of the orbital retrobulbar vasculature.

PURPOSE: The retrobulbar orbital vasculature is known to be complex and variable between individuals. This study aimed to produce a method to map the retrobulbar vessels, to generate 3D reconstructions, to visualise and to improve our understanding of their complexity. METHODS: Five human orbits donated under the Human Tissue Act (2004) were fixed in formalin, decalcified in 10% formic acid, and dehydrated in acetone at -20°C. Specimens were impregnated with epoxy resin, cured, and cut into 0.3 mm sections. Sections were stained with Gomori's trichrome stain, imaged, and reconstructed using 3D reconstruction software (BioVis3D, version 3.1). RESULTS: The arterial system was reconstructed in all five specimens. The superior ophthalmic vein (SOV) and the central retinal vein (CRV) were reconstructed in four specimens. E12 sheet plastination showed excellent results for histological analysis at a macroscopic level; however, anatomical topology was not entirely preserved on a microscopic level. Gomori's trichrome stain gave excellent results in highlighting axial sections of the arterial walls and their tunics, including finer calibre vessels, thus allowing detailed reconstruction of the arterial vasculature. Miller's stain for elastin showed poor results in differentiating vessels from soft tissue; venous vasculature was poorly identified with both stains. CONCLUSIONS: This study provided a detailed anatomical model of the retrobulbar orbital vascular system, a method that can be used for further studies to form a database relating to the topography of the arterial system. These models may be employed for teaching, and possible surgery planning, for both trainees and ophthalmic surgeons.

Positional Variation of the Infraorbital Foramen in Caucasians and Black Africans from Britain: Surgical Relevance and Comparison to the Existing Literature.

BACKGROUND: Midface augmentation and orbital surgery carry an inherent risk of injury to the infraorbital vascular bundle, especially the infraorbital nerve where it exits the infraorbital foramen (IOF). This can result in significant morbidity for the patient, including paresthesia and neuralgia. Studies report significant heterogeneity in IOF position according to gender, ethnicity, and laterality. A knowledge of the relationship of the IOF to regional soft tissue, bony landmarks, and its variation among ethnicities is likely to reduce iatrogenic injuries. METHODS: A single-center retrospective computed tomography (CT)-based study was conducted. Twenty Caucasians and 20 Black Africans patients were selected from an existing radiologic database at Moorfields Eye Hospital, London, UK. DICOM image viewing software (Syngo, Siemens Healthineers) was used to record the position of the IOF using standardized sagittal and axial views. RESULTS: There was a statistically significant difference in the horizontal position of the IOF in the 2 races (P = 0.00). The combined measurements were used to derive a rectangular zone of variability measuring 14.30 mm by 10.60 mm. This zone was found to lie 3.50 mm below the infraorbital rim, 7.10 mm medial to the piriform aperture, and 11.60 mm from the lateral orbital rim. CONCLUSION: A sound knowledge of key facial landmarks is necessitated when performing midface augmentation and orbital surgery. An anatomical safe zone depicting the variation of the IOF will help reduce iatrogenic injury to the infraorbital nerve and prevent patient morbidity.

Proposed three-dimensional model of the orbit and relevance to orbital fracture repair.

PURPOSE: To describe the relationship of the orbital rim and depth in Far Eastern skulls by anatomical study, using morphometry to yield an octagonal three-dimensional model of the orbit. METHODS: Forty-one orbits of 21 Far Eastern skulls from the Department of Anatomy of St George's, University of London were included in this study. A morphometric study was conducted, measuring between eight reproducible orbital rim landmarks to yield perimeters, and from these landmarks to the optic canal to yield orbital depth. Orbital height and width were also recorded. Results were statistically analysed to look for evidence of gender variation or laterality before comparison with those from other ethnicities. The authors then present a method for three-dimensional description of the orbit. RESULTS: 67 % of orbits were male. Orbital height and width were significantly greater in males (34.6 ± 2.0 and 39.4 ± 1.7, vs. 32.5 ± 2.3 and 37.2 ± 2.4 mm). Orbital perimeter tended towards being larger in males (126.3 vs. 122.2 mm, p = 0.05), as was the angle between medial and lateral walls (50.1° ± 2.0°, vs. 47.9° ± 3.0°). CONCLUSION: This study has proposed a new method for describing the orbit using three-dimensional measurements, yielding clinically useful morphometric data. These results and model have applications in surgical navigation of the orbit, repair of fractures, and prediction of post-traumatic or surgical enophthalmos.

Radiological Comparison of the Lacrimal Sac Fossa Anatomy Between Black Africans and Caucasians.

PURPOSE: To compare, in black Africans and Caucasians, the radiological anatomy of the intranasal structures and lacrimal sac fossa as relevant to dacryocystorhinostomy. METHODS: 0.75 mm section cranio-orbital computed tomography scans from 72 patients (42 black Africans and 30 Caucasian) were included in this retrospective observational case series. Only one orbit from each scan was utilized. The main outcome measures were: the thickness and proportions of the lacrimal bone and frontal process of the maxilla evaluated at 3 axial planes (upper, middle, lower) in the lacrimal sac fossa; 2 measurements of maxillary thickness were obtained at each plane-namely, the "midpoint thickness" and the "maximum thickness." The anterior extent of the nasal mucosa was also evaluated. RESULTS: The frontal process of the maxilla was thickest inferiorly (p < 0.001) and the maximum maxillary thickness was significantly thicker in black Africans as compared with Caucasians (p < 0.001) at all planes. At midfossa level, the proportion of maxillary bone forming the lacrimal fossa wall was significantly greater in black Africans (p < 0.01). In contrast, the length of nasal mucosa available for creation of an anastomosis, as estimated from the greatest mucosal height, was significantly greater in Caucasians (p < 0.01). CONCLUSIONS: Black Africans have a lacrimal sac fossa bounded by thicker maxillary bone, this bone constituting a higher proportion of the fossa wall at its midpoint, and also have significantly less nasal mucosa available for soft-tissue anastomosis during lacrimal drainage surgery. The anterior lacrimal crest, comprising the frontal process of the maxilla, was thickest at the lowest plane in both black Africans and Caucasians.

Surgical Outcomes of Different Deep Anterior Lamellar Keratoplasty Techniques-A Single-Centre UK Study.

Background: Anterior lamellar keratoplasty (ALK) is a less invasive procedure than PK, and thus avoids many of the intraocular complications associated with PK. DALK can be performed using several different techniques, with either a manual dissection, a keratome or femtosecond-laser assisted dissection, or with a big bubble technique. To analyse the outcomes and compare the results of three deep anterior lamellar keratoplasty (DALK) techniques. Methods: This study included 105 DALK cases performed at Queen Victoria Hospital, East Grinstead, UK, in the period between January 2016 and May 2022. Cases were classified into four groups based on technique: BB-DALK, manual DALK, FS-DALK and 'converted to PK group'. Results: There was significant improvement in VA and Kmax compared to the preoperative values in all groups. There was no significant difference detected in VA and Kmax between all groups. Conclusions: Performing DALK surgery with any suitable technique (manual, big-bubble or femtosecond-assisted) is effective and causes significant improvements in VA and Kmax, even in cases where a conversion to penetrating keratoplasty is required. However, every technique has its pros and cons and should be tailored according to surgeon preference and individual case pathology.

Supraorbital notch and foramen: positional variation and relevance to direct brow lift.

PURPOSE: Forehead paresthesia after brow lift is well-documented with rates as high as 40.7%. The authors describe an anatomical study to identify the variation in position of the supraorbital notch/foramen to define safe limits for deep dissection during this procedure. METHODS: Sixty-six orbits from 23 dry skulls and 9 formalin-fixed cadavers were analyzed photographically using ImageJ software. The cadaveric specimens were dissected using a coronal incision, which allowed the inferior resection of the frontalis muscle and periosteum. The exit point of the supraorbital neurovascular bundle was noted as a foramen or notch. The position of the supraorbital notch or foramen was recorded in relation to the midline as defined by the sagittal suture at the level of the highest point of the supraorbital rim. The distance and angle for each foramen/notch were calculated. RESULTS: Thirty-three percent of orbits had a foramen. The average distance from the midpoint to the foramen was 25.24 mm (standard deviation 3.78 mm) and to the notch was 22.69 mm (22.69 mm). The range of distance between the midpoint and the foramen/notch was 17.62 to 32.35 mm. The average angle between the horizontal meridian and the foramen was 81/57° (standard deviation 4.69°). CONCLUSIONS: A wide variation in anatomy was seen. Greater caution is required when performing deep dissection around the supraorbital notch because of the variation in position of the supraorbital foramen.

Lessons from the past: cribra orbitalia, an orbital roof pathology.

AIMS: To define a computed tomography protocol that may be used in future clinical practice for the reliable detection and analysis of cribra orbitalia. MATERIALS AND METHODS: Two osteological assemblages from the Museum of London were used to select 13 cribratous skulls and 5 non-cribratous skulls. Area of cribra orbitalia was measured using image analysis. Morphology of cribra orbitalia, orbital roof density and the associated optic canal diameter was analysed using computed tomography reconstructions. RESULTS: The presence of cribra orbitalia was associated with changes in the internal diploë layer as well as the cortical bone table. A novel radiological grading system and protocol was developed to identify the pathology. A decrease in the orbital roof density by 210 Hounsfield units and a reduction in the optic canal diameter, up to 1 mm, were found to be associated with the presence of cribra orbitalia. CONCLUSIONS: The occurrence of cribra orbitalia is found to be associated with stenosis of the optic canal, and could explain a proportion of cases ofoptic nerve entrapment. This study provides a guideline for radiologists and oculoplastic surgeons to help detect the presence of cribra orbitalia in suspected patients.

Ex-vivo study on the surface quality of corneal lenticule and stroma after low energy femtosecond laser lenticule extraction.

This study aimed to assess the surface quality of cap, stroma and lenticular surfaces created using low-energy femtosecond laser lenticule extraction (Ziemer FEMTO LDV Z8). Twenty-four porcine eyes were divided into four groups (n = 6 each): two with optimal laser power (32%) with posterior curvature equivalent to a spherical correction of -2D and -5D, respectively and the other two with high power (64%) with spherical correction of -2D and -5D respectively. Samples were analysed using scanning electron microscopy (SEM). Surface morphology was evaluated using a standard scoring system; surface relief, surface regularity, extent and position of irregularities were graded by four independent clinicians. Eyes with 32% power and -2D correction had significantly less size of the irregular area than those with -5D; however, no significant difference was found between the two groups with 64% power. When comparing eyes with -2D correction, the size of the irregular area was lesser with 32% power. Surface relief was lesser with -5D correction with 32% power than 64% power. Low-energy femtosecond laser lenticule extraction (Ziemer FEMTO LDV Z8) produces good surface quality results. There is a tendency for smoother surface stromal quality with lower power settings than a higher power.

A Review of Smartphone Apps Used for Toric Intraocular Lens Calculation and Alignment.

Smartphone apps are becoming increasingly popular in ophthalmology, one specific area of their application being toric intraocular lens (IOL) surgery for astigmatism correction. Our objective was to identify, review and objectively score smartphone apps applicable to toric IOL calculation and/or axis alignment. This review was divided into three phases. A review was conducted on four major app databases (phase I): National Health Service (NHS) Apps Library, Google Play Store, Apple App Store and Amazon Appstore. A systematic literature review (phase II) was conducted to identify studies for included apps in phase I of our study. Keywords used in both searches included: "toric lens", "toric IOL", "refraction", "astigmatism", "ophthalmology", "eye calculator", "ophthalmology calculator" and "refractive calculator". Included apps were objectively scored (phase III) by three independent reviewers using the mobile app rating scale (MARS), a validated tool that ranks the quality of mobile health apps using a calculated mean app quality (MAQ) score. Phase I of our study screened 2428 smartphone apps, of which six apps for toric IOL calculation and four apps for axis marking were eligible and were selected for quantitative analysis. Phase II of our study screened 477 studies from PubMed, Medline and Google Scholar. Three studies validating two apps (toriCAM, iToric Patwardhan) in a clinical setting as adjunct tools for preoperative axis marking were identified. Phase III ranked Toric Calculator for iPhone (Apple iOS, MAQ 4.13; average MAQ 3.34 ± 0.54) as the highest-scoring toric IOL calculator, and iToric Patwardhan (Android OS, MAQ 4.13; average MAQ 3.41 ± 0.44) was the highest-scoring axis marker in our study. Our review identified and objectively scored ten smartphone apps available for toric IOL surgery adjuncts. Toric Calculator for iPhone and iToric Patwardhan were the highest-scoring toric IOL calculator and axis marker, respectively. Current literature, though limited, suggests that axis marking smartphone apps can achieve similar levels of misalignment reduction when compared to digital systems.

Comparison of Anterior Corneal Aberrometry, Keratometry and Pupil Size with Scheimpflug Tomography and Ray Tracing Aberrometer.

This study aimed to assess the anterior corneal wavefront aberrations, keratometry, astigmatism vectors and pupil size between Pentacam HR® (Oculus Optikgeraete GmbH, Wetzlar, Germany) and iTrace® (Tracey Technologies Corp., Houston, TX, USA). In this observational study, 100 eyes (50 healthy volunteers) were scanned in mesopic light condition with a Pentacam HR® and iTrace®. Anterior corneal aberrations (spherical aberration (Z40), vertical coma (Z3 − 1), horizontal coma (Z3 + 1)), keratometry in the flattest (K1) and steepest meridian (K2), mean astigmatism, astigmatic vectors (J0 and J45), and pupil size were measured. We found a significant difference in Z40 (Pentacam®: +0.30 ± 0.11 µm and iTrace®: −0.03 µm ± 0.05 µm; p < 0.01) with no correlation between the devices (r = −0.12, p = 0.22). The devices were in complete agreement for Z3 − 1 (p = 0.78) and Z3 + 1 (p = 0.39), with significant correlation between the machines (r = −0.38, p < 0.01 and r = −0.6, p < 0.01). There was no difference in K1, K2 and mean astigmatism. J0 was negative with both devices (against-the-rule astigmatism), but there was no correlation. J45 was negative with the Pentacam HR® (more myopic oblique astigmatism) but significantly correlated between the devices. Pupil size was smaller with Pentacam HR® (p < 0.01). In summary, these devices cannot be used interchangeably. Corneal Z40 was significantly different with more negative Z40 with iTrace® compared to Pentacam HR®. iTrace® operates with lower illumination, giving larger pupil size than Pentacam HR®, which uses intense blue light during measurement. No correlation was found for J0. Pentacam HR® had a trend to record more negative J45 (myopic oblique astigmatism).

Low-tech intraocular ophthalmic microsurgery simulation: A low-cost model for home use.

In order to maintain manual dexterity and surgical skills, trainees are encouraged to partake in regular simulation. Current options for intraocular surgical simulation require specialist microscopic equipment which is expensive and requires access to simulation facilities. A set of core simulation exercises and basic surgical skills of performing the corneal incisions, capsulorhexis, improving the manual dexterity, and suturing were identified, discussed, and agreed among authors before designing this simulation exercise. In this paper, we propose a smartphone-based, low-cost, low-tech model with corresponding exercises for intraocular simulation that can be used at home for the above-mentioned surgical skill set. This model provides an easy, portable, and reproducible method of simulation and can serve as an adjunct to patient-facing surgical training, especially in the current pandemic, where the excess to the simulation facilities or setup of these facilities may be difficult.

Cataract service redesign in the post-COVID-19 era.

COVID-19 pandemic of 2020 has impacted all aspects of clinical practice in the UK. Cataract services suffered severe disruption due to necessary measures taken to reduce elective surgery in order to release capacity to support intensive care requirements. Faced with a potential 50% increase in cataract surgery workload per week in the post-COVID-19 world, eye units should use this event to innovate, not just survive but to also evolve for a sustainable future. In this article, we discuss the inadequacies of existing service rationing options to tackle the COVID-19 cataract backlog. This includes limiting rationing based on visual acuity, limiting surgery to first or only seeing eyes, and postponing clinic and surgical dates according to referral dates. We propose units use the lockdown time to reset and develop a comprehensive patient-centred care pathway using principles of value-based healthcare: the cataract integrated practice units. Developing an agile surgical database that incorporates all aspects of patient need from education to follow-up in their individual cataract journey will allow units to react and plan quickly in the early phase of recovery and beyond. We also discuss the considerations units should bear in mind on telemedicine, modifications for face-to-face clinics, theatre organisation and options of expanding cataract throughput capacity. The pause in elective surgery due to the pandemic may have provided cataract services a rare opportunity to reset and transform cataract service pathways for the digital era.

Aerosol generation through pars plana vitrectomy.

PURPOSE: To assess whether pars plana vitrectomy (PPV) is an aerosol-generating procedure (AGP) in an ex vivo experimental model. METHODS: In this ex vivo study on 10 porcine eyes, optical particle counter was used to measure particles ≤10 µm using cumulative mode in the six in-built channels: 0.3 µm, 0.5 µm, 1 µm, 2.5 µm, 5 µm and 10 µm aerosols during PPV. Two parts of the study were as follows: (1) to assess the pre-experimental baseline aerosol count in the theatre environment where there are dynamic changes in temperature and humidity and (2) to measure aerosol generation with 23-gauge and 25-gauge set-up. For each porcine eye, five measurements were taken for each consecutive step in the experiment including pre-PPV, during PPV, fluid-air exchange (FAX) and venting using a flute with 23-gauge set-up and a chimney with 25-gauge set-up. Therefore, a total of 200 measurements were recorded. RESULTS: With 23-gauge and 25-gauge PPV, there was no significant difference in aerosol generation in all six channels comparing pre-PPV versus PPV or pre-PPV versus FAX. Venting using flute with 23-gauge PPV showed significant reduction of aerosol ≤1 µm. Air venting using chimney with 25-gauge set-up showed no significant difference in aerosol of ≤1 µm. For cumulative aerosol counts of all particles measuring ≤5 µm, compared with pre-PPV, PPV or FAX, flute venting in 23-gauge set-up showed significant reduction unlike the same comparison for chimney venting in 25-gauge set-up. CONCLUSION: PPV and its associate steps do not generate aerosols ≤10 µm with 23-gauge and 25-gauge set-ups.

Aerosol generation through phacoemulsification.

PURPOSE: To evaluate whether phacoemulsification is an aerosol-generating procedure in an ex vivo experimental model. SETTING: Sussex Eye Hospital, Brighton, United Kingdom. DESIGN: Experimental study. METHODS: In this ex vivo study on 15 porcine eyes, an optical particle counter was used to measure particles of 10 µm and less using the cumulative mode based on the 6 in-built channel sizes. The 2 parts of the study were to: (1) assess the efficacy of the particle counter in the theater environment where there are dynamic changes in temperature and humidity; and (2) to measure aerosol generation with 3 phacoemulsification settings: (i) continuous power with 80% longitudinal (5 eyes); (ii) continuous power with 100% torsional (5 eyes); and (iii) continuous power with 80% longitudinal with application of hydroxypropyl methylcellulose (HPMC) on the ocular surface (5 eyes). Five measurements were taken prephacoemulsification and 5 during phacoemulsification per eye therefore totaling 75 measurements. RESULTS: Maximum aerosols were captured when the counter faced the aerosol source. There was no significant difference in aerosol generation of all sizes during each phacoemulsification setting with torsional, longitudinal, and longitudinal with HPMC (P > .01). Combining data of all 3 phacoemulsification settings (150 measurements from 15 eyes), there was no significant difference comparing prephacoemulsification and during phacoemulsification for aerosols of 5 µm or less (1455 vs 1363.85, P = .60), more than 5 to 10 µm (1.5 vs 1.03, P = .43), and of 10 µm or less (1209 vs 1131.55, P = .60). CONCLUSIONS: Phacoemulsification did not generate aerosols of 10 µm or less with continuous power using 80% longitudinal, 100% torsional, and 80% longitudinal setting with HPMC on the surface.

Ophthalmic Workplace Modifications for the Post-COVID Era.

The COVID-19 pandemic necessitates implementation of exposure control measures in all facets of the healthcare sector. Healthcare professionals who work in busy ophthalmology clinics and theaters are amidst the highest at-risk of contracting COVID-19. The authors review the up-to-date scientific evidence of SARS-CoV-2 transmission to demystify and explain the exposure control options available for ophthalmic workplace and offer insights from an industrial hygiene standpoint. As the we enter the post-COVID world, these measures will be critical to enhance workplace safety, and thus protect patients and staff alike.

Basic skin surgery interactive simulation: system description and randomised educational trial.

BACKGROUND: Learning the skills required for open surgery is essential for trainee progression towards more advanced technical procedures. Simulation supports skill enhancement at a time when exposure to actual surgical procedures and traditional apprentice-based teaching has declined. The proliferation of smartphone and tablet devices with rich, touch sensitive displays and increasing processing power makes a compelling argument for expanding accessibility further by development of mobile virtual simulations for training on demand in any setting, at any time.We present a tablet-based mobile simulation App for educating surgical trainees in the planning and surgical procedures involved in facial lesion resection and local skin flap surgery. METHODS: Novel algorithms were developed and modules included in a mobile simulation App to teach concepts required for three defect reconstruction techniques: elliptical closure, bilateral advancement (H flap) and the semi-circular rotation flap, with additional resources such as videos and formal guidelines made available at relevant points in the simulation. A randomised educational trial was conducted using the mobile simulation App with 18 medical students that were divided equally into two groups: the intervention group learning using the new mobile simulation App, and a control group, undergoing traditional text-based self-study. The students were then assessed on knowledge and skills' acquisition through an MCQ and a task analysis score. RESULTS: There was a statistically significant difference between the scores of students in the intervention group and the students in the non-intervention group in both forms of assessment, with an average multiple-choice assessment score of 62.95% points versus 56.73%, respectively (p = 0.0285), and an average task analysis score of 3.53 versus 2.58, respectively (p = 0.0139). CONCLUSIONS: Touch-based simulation provided an efficient and superior method of learning three different local flap techniques for facial soft tissue reconstruction, and helped recalling steps involved in the surgery in a fluid manner that also improved task performance.