Upper gastrointestinal training in the UK and Ireland: a Roux Group Study

INTRODUCTION

Surgical training programmes in the United Kingdom and Ireland (UK&I) are in a state of flux. This study aims to report the contemporary opinions of trainee and consultant surgeons on the current upper gastrointestinal (UGI) training model in the UK&I.

METHODS

A questionnaire was developed and distributed via national UGI societies. Questions pertained to demographics, current training evaluation, perceived requirements and availability.

RESULTS

A total of 241 responses were received with representation from all UK&I postgraduate training regions. The biggest discrepancies between rotation demand and national availability related to advanced/therapeutic endoscopy and robotic surgery, with 91.7% of respondents stating they would welcome greater geographical flexibility in training. The median suggested academic targets were 3-5 publications (trainee vs consultant <3 vs 3-5, p<0.001); <3 presentations (<3 vs 3-5, p=0.002); and 3-5 audits/quality improvement projects (<3 vs 3-5, p<0.001). Current operative requirements were considered achievable (87.6%) but inadequate for day one consultant practice (74.7%). Reassuringly, 76.3% deemed there was role for on-the-job operative training following consultant appointment. Proficiency in diagnostic endoscopy was considered a minimum requirement for Certificate of Completion of Training (CCT) yet the majority regarded therapeutic endoscopy competency as non-essential. The median numbers of index UGI operations suggested were comparable with the current curriculum requirements. Post-CCT fellowships were not considered necessary; however, the majority (73.6%) recognised their advantage.

CONCLUSIONS

Current CCT requirements are largely consistent with the opinions of the UGI community. Areas for improvement include flexibility in geographical working and increasing national provisions for high-quality endoscopy training.

Six-year cumulative treatment effect and treatment efficacy of a dual focus myopia control contact lens

PURPOSE

Accumulated axial growth observed during a 6-year clinical trial of a dual focus myopia control contact lens was used to explore different approaches to assess treatment efficacy.

METHODS

Axial length measurements from 170 eyes in a 6-year clinical trial of a dual focus myopia control lens (MiSight 1 day, CooperVision) were analysed. Treatment groups comprised one having undergone 6 years of treatment and the other (the initial control group) having 3 years of treatment after 3 years of wearing a single vision control lens. Efficacy was assessed by comparing accumulated ocular growth during treatment to that expected of untreated myopic and emmetropic eyes. The impact of treatment on delaying axial growth was quantified by comparing the increased time required to reach criterion growths for treated eyes and survivor analysis approaches.

RESULTS

When compared to the predicted accumulated growth of untreated eyes, 6 years of treatment reduced growth by 0.52 mm, while 3 years of treatment initiated 3 years later reduced growth by 0.19 mm. Accumulated differences between the growth of treated and untreated myopic eyes ranged between 67% and 52% of the untreated myopic growth, and between 112% and 86% of the predicted difference in growth between untreated myopic and age-matched emmetropic eyes. Treated eyes took almost 4 years longer to reach their final accumulated growth than untreated eyes. Treatment increased the time to reach criterion growths by 2.3-2.7 times.

CONCLUSION

Estimated growth of age-matched emmetropic and untreated myopic eyes provided evidence of an accumulated slowing in axial elongation of 0.52 mm over 6 years, and the treated growth remained close to that expected of emmetropic eyes. Six years of dual focus myopia control delayed the time to reach the final growth level by almost 4 years.

'How I'm feeling today, I probably won't be feeling tomorrow'. Using I-Poems to explore young people's changing emotions during the Covid-19 pandemic - A qualitative, longitudinal study

Background

Relatively little published qualitative research has explored children and young people's (CYP) prolonged or longitudinal experiences of the pandemic, and their emotional responses to such unreserved change to everyday life. As part of a broader, qualitative longitudinal study, this paper explores change and continuity in young people's emotions over time during the Covid-19 pandemic in North East England.

Methods

I-Poems were curated for each of the 26 young people in this study from serial interview transcripts and diary entries, collected over the course of 16 months. Creation of I-Poems require researchers to focus on sentences made by the interviewee that include the word "I," and without changing the order of those sentences, to present them in poetic stanzas.

Findings

Young people's voices and experiences became more poignant and powerful when their 'I' narrative was centralised, silencing the presence of the researcher. Further, presenting the data in this way allowed us to see how the following emotions shifted over time: grief, sadness, frustration, anger, anxiety, joy, pleasure, excitement. We contend that young people experienced significant rupture and change over the course of our 16 month project, with both positive and negative repercussions for their emotional wellbeing.

Conclusions

Large scale (quantitative and qualitative) studies remain much needed to focus on the long-term impacts of the pandemic on young people's social, emotional and cultural lives. Longitudinal and creative qualitative approaches (such as I-Poems) have the potential to centralise participant voice, break down power dynamics, and allow exploration of shifting experiences and emotions over time.

Myopia Control Dose Delivered to Treated Eyes by a Dual-focus Myopia-control Contact Lens

PURPOSE

This study examined the optical impact of a DF contact lens during near viewing in a sample of habitual DF lens wearing children.

METHODS

Seventeen myopic children aged 14 to 18 years who had completed 3 or 6 years of treatment with a DF contact lens (MiSight 1 Day; CooperVision, Inc., San Ramon, CA) were recruited and fit bilaterally with the DF and a single-vision (Proclear 1 Day; CooperVision, Inc.) contact lens. Right eye wavefronts were measured using a pyramidal aberrometer (Osiris; CSO, Florence, Italy) while children accommodated binocularly to high-contrast letter stimuli at five target vergences. Wavefront error data were used to compute pupil maps of refractive state.

RESULTS

During near viewing, children wearing single-vision lenses accommodated on average to achieve approximate focus in the pupil center but, because of combined accommodative lag and negative spherical aberration, experienced up to 2.00 D of hyperopic defocus in the pupil margins. With DF lenses, children accommodated similarly achieving approximate focus in the pupil center. When viewing three near distances (0.48, 0.31, and 0.23 m), the added +2.00 D within the DF lens treatment optics shifted the mean defocus from +0.75 to -1.00 D. The DF lens reduced the percentage of hyperopic defocus (≥+0.75 D) in the retinal image from 52 to 25% over these target distances, leading to an increase in myopic defocus (≤-0.50 D) from 17 to 42%.

CONCLUSIONS

The DF contact lens did not alter the accommodative behavior of children. The treatment optics introduced myopic defocus and decreased the amount of hyperopically defocused light in the retinal image.

Assessment of groundwater salinity using principal component analysis (PCA): a case study from Mewat (Nuh), Haryana, India

In the present study, principal component analysis (PCA) is used to investigate the processes controlling groundwater salinity in the Mewat (Nuh) district, Haryana, India. Twenty groundwater samples were collected from salinity-affected areas in the March-April months of years 2018 and 2019 and were analyzed for chemical variables pH, EC, Ca²⁺, Mg²⁺, Na⁺, K⁺, [Formula: see text], Cl^-, SO₄^2-, [Formula: see text], TDS, and total hardness. Three principal components were selected based on the eigen value, which explains 79.58% and 85.08% of the total variation in the years 2018 and 2019, respectively. The first principal component (PC-1) is identified with salinity, the second principal component (PC-2) with alkalinity, and the third principal component (PC-3) described the pollution. When the yearly comparison was made, the samples collected in 2019 were found to have an increased salinity compared to 2018, which shows an increased vulnerability to the aquifer of Mewat on account of the decline in rainfall recharge. It was also evident that declining recharge also triggered the recharge from other sources; thus, the impact of pollution is more pronounced in 2019 compared to 2018.

P-031 AN UNUSUAL CASE OF AN INCARCERATED 5MM PORT SITE HERNIA FOLLOWING LAPAROSCOPIC FUNDOPLICATION

Aim

Port site hernias are a rare, but recognised risk of laparoscopic surgery. Literature supports fascial closure at port sites of 10mm or greater. However, there are few reported cases of herniation through 5mm port sites.

Methods

This case report focuses on a 67-year-old female who underwent an uncomplicated primary laparoscopic Toupet's fundoplication. 11 days post procedure she presented with an incarcerated port site hernia. CT scan demonstrated high grade small bowel obstruction with a transition point at the site of the 5mm right sided port. A laparotomy was performed, the hernia reduced, small bowel was viable, and the port site hernia was closed internally using vicryl sutures.

Results

The incidence of 5mm trocar-site hernias is rare. A recent literature review found only 10 such cases related to general surgery (cholecystectomy:6; appendicectomy: 2; right hemicolectomy: 1; paraesophageal hernia:1). Risk factors for port-site hernias include: high BMI, midline position, size, number and type of trocar tip. The limited current literature identifies excessive trocar manipulation as the major risk factor for developing 5mm port-site hernias, yet routine fascial closure is not supported.

Conclusion

Herniation at 5mm port sites is rare but attention should be paid when patients present with symptoms suggesting its occurrence.

Severity of oEsophageal Anastomotic Leak in patients after oesophagectomy: the SEAL score

Background

Anastomotic leak (AL) is a common but severe complication after oesophagectomy. It is unknown how to determine the severity of AL objectively at diagnosis. Determining leak severity may guide treatment decisions and improve future research. This study aimed to identify leak-related prognostic factors for mortality, and to develop a Severity of oEsophageal Anastomotic Leak (SEAL) score.

Methods

This international, retrospective cohort study in 71 centres worldwide included patients with AL after oesophagectomy between 2011 and 2019. The primary endpoint was 90-day mortality. Leak-related prognostic factors were identified after adjusting for confounders and were included in multivariable logistic regression to develop the SEAL score. Four classes of leak severity (mild, moderate, severe, and critical) were defined based on the risk of 90-day mortality, and the score was validated internally.

Results

Some 1509 patients with AL were included and the 90-day mortality rate was 11.7 per cent. Twelve leak-related prognostic factors were included in the SEAL score. The score showed good calibration and discrimination (c-index 0.77, 95 per cent c.i. 0.73 to 0.81). Higher classes of leak severity graded by the SEAL score were associated with a significant increase in duration of ICU stay, healing time, Comprehensive Complication Index score, and Esophagectomy Complications Consensus Group classification.

Conclusion

The SEAL score grades leak severity into four classes by combining 12 leak-related predictors and can be used to the assess severity of AL after oesophagectomy.

Catastrophe optics theory unveils the localised wave aberration features that generate ghost images

Monocular polyplopia (ghost or multiple images) is a serious visual impediment for some people who report seeing two (diplopia), three (triplopia) or even more images. Polyplopia is expected to appear if the point spread function (PSF) has multiple intensity cores (a dense concentration of a large portion of the radiant flux contained in the PSF) relatively separated from each other, each of which contributes to a distinct image. We present a theory that assigns these multiple PSF cores to specific features of aberrated wavefronts, thereby accounting optically for the perceptual phenomenon of monocular polyplopia. The theory provides two major conclusions. First, the most likely event giving rise to multiple PSF cores is the presence of hyperbolic, or less probably elliptical, umbilic caustics (using the terminology of catastrophe optics). Second, those umbilic caustics formed on the retinal surface are associated with certain points of the wave aberration function, called cusps of Gauss, where the gradient of a curvature function vanishes. However, not all cusps of Gauss generate those umbilic caustics. We also provide necessary conditions for those cusps of Gauss to be fertile. To show the potential of this theoretical framework for understanding the nature and origin of polyplopia, we provide specific examples of ocular wave aberration functions that induce diplopia and triplopia. The polyplopia effects in these examples are illustrated by depicting the multi-core PSFs and the convolved retinal images for clinical letter charts, both through computer simulations and through experimental recording using an adaptive optics set-up. The number and location of cores in the PSF is thus a potentially useful metric for the existence and severity of polyplopia in spatial vision. These examples also help explain why physiological pupil constriction might reduce the incidence of ghosting and multiple images of daily objects that affect vision with dilated pupils. This mechanistic explanation suggests a possible role for optical phase-masking as a clinical treatment for polyplopia and ghosting.

Long-term Effect of Dual-focus Contact Lenses on Myopia Progression in Children: A 6-year Multicenter Clinical Trial

SIGNIFICANCE

Treatment of myopic children with a dual-focus soft contact lens (DFCL; MiSight 1 day) produced sustained slowing of myopia progression over a 6-year period. Significant slowing was also observed in children switched from a single vision control to treatment lenses (3 years in each lens).

PURPOSE

This study aimed to evaluate the effectiveness of DFCLs in sustaining slowed progression of juvenile-onset myopia over a 6-year treatment period and assess myopia progression in children who were switched to a DFCL at the end of year 3.

METHODS

Part 1 was a 3-year clinical trial comparing DFCLs with a control contact lens (Proclear 1 day) at four investigational sites. In part 2, subjects completing part 1 were invited to continue for 3 additional years during which all children were treated with MiSight 1 day DFCLs (52 and 56 from the initially treated [T6] and control [T3] groups, respectively). Eighty-five subjects (45 [T3] and 40 [T6]) completed part 2. Cyclopleged spherical equivalent refractive errors (SEREs) and axial lengths (ALs) were monitored, and a linear mixed model was used to compare their adjusted change annually.

RESULTS

Average ages at part 2 baseline were 13.2 ± 1.3 and 13.0 ± 1.5 years for the T6 and T3 groups, respectively. Slowed myopia progression in the T6 group observed during part 1 was sustained throughout part 2 (mean ± standard error of the mean: change from baseline SERE [in diopters], -0.52 ± 0.076 vs. -0.51 ± 0.076; change in AL [in millimeters], 0.28 ± 0.033 vs. 0.23 ± 0.033; both P > .05). Comparing progression rates in part 2 for the T6 and T3 groups, respectively, indicates that prior treatment does not influence efficacy (SERE, -0.51 ± 0.076 vs. -0.34 ± 0.077; AL, 0.23 ± 0.03 vs. 0.18 ± 0.03; both P > .05). Within-eye comparisons of AL growth revealed a 71% slowing for the T3 group (3 years older than part 1) and further revealed a small subset of eyes (10%) that did not respond to treatment.

CONCLUSIONS

Dual-focus soft contact lenses continue to slow the progression of myopia in children over a 6-year period revealing an accumulation of treatment effect. Eye growth of the initial control cohort with DFCL was slowed by 71% over the subsequent 3-year treatment period.

341 Consenting Practices in Plastic Surgery

Introduction

Informed consent is a vital aspect of safe patient care within any surgical specialty, and if not completed thoroughly, may result in misinformation and patient dissatisfaction.

Traditional paper consent forms are notoriously poorly completed by medical professionals, with common issues ranging from ineligible handwriting, to missing key components of the form.

The aim of this audit was to assess our departments’ compliance with standard trust consent forms and compare adherence to local and national consenting policies.

Method

All elective and emergency plastic surgical procedures carried out over a one-week period from 17/05/2021 to 23/05/2021 were identified using eTrauma and Cerner operative records. In total, 40 procedures were identified. Consent forms were then reviewed and assessed for completion in key areas. 4 procedures were excluded due to the consent form not being available for review, and 1 procedure was excluded due to a cancellation.

Results

The risks and benefits of procedures were generally documented to a high standard. Providing written information to patients, confirmation of consent if the procedure was being performed on a different day, and possible additional procedures were poorly completed throughout. 90% of consent forms screened, failed to include confirmation of the surgical site within the specific section of the form.

Conclusions

Overall, the department demonstrated good compliance with completing trust consent forms. Electronic consent forms would likely address the shortcomings identified in this audit and should be adopted. Continued responsibility from the whole team should be highlighted and maintained to ensure a high standard of consenting.

61 Use of Ketamine Sedation for the Treatment of Minor Plastic Surgery Procedures in the Paediatric Emergency Department

Aim

To determine if ketamine sedation is a safe and cost-effective way of treating paediatric patients presenting with minor injuries, requiring plastic surgery procedures, in the emergency department.

Method

A retrospective cohort study was carried out over a 9-month period in children between ages 18 months and 16 years old, presenting to the paediatric emergency department at Chelsea and Westminster Hospital with minor injuries requiring plastic surgery input. The data collected included previously validated co-primary outcome measures of surgical site infection at 7 days and cosmetic appearance summary score at a minimum of 4 months. Parental satisfaction surveys were completed at 4 months to assess perceived quality of treatment. A cost analysis comparison against procedures completed under general anaesthetic was also undertaken.

Results

During the 9-month period of study, 24 minor procedures were performed under ketamine in the paediatric emergency department. There were no serious adverse events recorded. Three cases exceeded the recommended 20-minute maximum procedure duration, but there was no associated adverse outcome. No cases required further procedures under general anaesthesia and there were no cases of surgical site infections at 7 days. Parents reported extremely favourable outcomes using this technique, with an average overall satisfaction score of 9.2 (assessed over a number of parameters, where 10 is complete satisfaction).

Conclusions

Ketamine procedural sedation in the paediatric population is a safe and cost-effective method for the treatment of minor plastic surgery procedures, with low risk for surgical site infection post-operatively, and high parent satisfaction rates

POS0926 NORMALIZATION OF HIGH SENSITIVITY CRP VERSUS CLINICAL RESPONSE TO IXEKIZUMAB AT WEEK 16 IN PATIENTS WITH RADIOGRAPHIC & NON-RADIOGRAPHIC AXIAL SPONDYLOARTHRITIS: RESULTS FROM THE COAST STUDIES

Background:

C-reactive protein (CRP), an objective marker of inflammation, can be used to monitor treatment response to biologics in patients with axial spondyloarthritis (axSpA) in addition to evaluating signs & symptoms. CRP is not elevated in all patients with active axSpA questioning its validity as a universal biomarker of response. Ixekizumab (IXE) demonstrated efficacy in axSpA treatment irrespective of baseline (BL) CRP levels. However, response to IXE categorized on CRP change from BL is unknown.

Objectives:

To evaluate response to IXE treatment from BL through week (wk) 16 in patients with axSpA categorized according to change in high sensitivity (hs) CRP.

Methods:

COAST-V (NCT 02696785),-W (NCT02696798), & -X (NCT02757352), were phase 3, multicentre, randomized, controlled trials, investigating the efficacy of IXE 80 mg every 4 & 2 wks in patients with: r-axSpA naïve to biologic disease-modifying antirheumatic drugs (bDMARDs; COAST-V); or who were inadequate responders/intolerant to tumour necrosis factor inhibitors (TNFi; COAST-W); or who fulfilled Assessment of SpondyloArthritis International Society (ASAS) criteria for non-radiographic (nr)axSpA (COAST-X).

This post hoc analysis focuses on approved dosing regimens. Depending on BL and wk 16 hsCRP values, patients were categorised as stable low (hsCRP ≤5 mg/L at BL & ≤5 mg/L at wk 16), normalized (hsCRP >5 mg/L at BL & ≤5 mg/L at wk 16) or elevated (hsCRP >5 mg/L at wk 16, irrespective of BL hsCRP). An absolute cutoff of 5 mg/L was used as the stratification factor in all COAST studies. Data were analyzed by treatment arm. Each trial was analyzed separately.

For hsCRP subgroups, patient demographics & other characteristics at BL, as well as trajectory over time for the endpoints ASAS40 & Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) 50 are described. Non-responder imputation was used for missing values.

Results:

In all studies at BL, disease activity & MRI SPARCC score were higher in normalized & elevated subgroups compared to the stable low subgroup - a.

In COAST-V, ASAS40 & BASDAI50 response was observed in IXE-treated patients regardless of hsCRP change status by wk 16 vs placebo. The highest ASAS40 & BASDAI50 response rate was reported in patients with normalized hsCRP - b. Similar findings were observed in COAST-W & -X.

Table 1.

Baseline Patient demographics & other characteristics - ITT population, per CRP subgroup

COAST-V(r-axSpA, bDMARD naive)COAST-W(r-axSpA, inadequate responders /intolerant to TNFi)COAST-X(non-radiographic axSpA, bDMARD naïve)Stable low (n=79)Norma-lized (n=80)Elevated (n=98)Stable low(n=58)Norma-lized (n=34)Elevated (n=126)Stable low (n=78)Norma-lized(n=40)Elevated (n=81)ParameterAge (years)43.7 (12.1)38.9 (10.9)42.7 (12.0)50.4 (13.3)46.1 (13.8)45.7 (12.5)44.0 (12.8)37.2 (14.6)38.7 (12.8)Male gender, n (%)63 (79.7)71.0 (88.8)78 (79.6)39.0 (67.2)30 (88.2)109 (86.5)35 (44.9)23 (57.5)34 (42)Duration of symptoms since axSpA onset (years)17.5 (11.2)14.4 (9.3)16.1 (9.9)21.7 (12.9)16.8 (11.6)18.9 (10.9)12.1 (9.9)10.3 (9.7)9.5 (9.0)HLA-B27 positive, n (%)69 (87.3)75.0 (93.8)89 (90.8)31.0 (91.2)101 (80.2)101 (80.2)48 (61.5)31 (77.5)67 (82.7)BASDAI Total Score6.5 (1.4)6.7 (1.5)7.0 (1.1)7.4 (1.5)7.3 (1.3)7.4 (1.3)6.9 (1.5)7.1 (1.6)7.2 (1.5)ASDAS Total Score3.1 (0.5)3.9 (0.6)4.2 (0.7)3.5 (0.6)4.3 (0.6)4.4 (0.8)3.2 (0.6)4.2 (0.8)4.2 (0.9)Spinal Pain due to AS7.0 (1.5)7.0 (1.5)7.5 (1.3)7.8 (1.5)7.7 (1.5)7.9 (1.4)7.2 (1.7)7.5 (1.7)7.5 (1.6)Patients with peripheral articular manifestations (>=1 TJC or >=1 SJC)47 (59.5)40 (50)62 (63.3)43 (74.1)24 (70.6)86 (68.3)56 (71.8)33 (82.5)66 (81.5)MRI Spine SPARCC ScoreMRI SIJ SPARCC ScoreMRI SPARCC Score6.7 (11.2)21.8 (27.3)20.7 (25.7)1.2 (2.3)7.0 (7.6)10.4 (17.0)5.2 (6.6)6.1 (8.2)6.2 (10.5)

Conclusion:

IXE reduced clinical disease activity in patients with axSpA irrespective of hsCRP change from BL to wk 16. Improvement in hsCRP level was associated with overall response rates.

Acknowledgements:

The authors would like to acknowledge Philana Fernandes, an employee of Eli Lilly and Company, for her for writing and editorial support.

Disclosure of Interests:

Helena Marzo-Ortega Consultant of: Celgene, Janssen, Eli Lilly, Novartis, Pfizer, UCB, Grant/research support from: Janssen, Novartis, Xavier Juanola: None declared, Tadashi Okano Speakers bureau: Asahi Kasei, Astellas, Abbvie, Ayumi, Chugai, Daiichi-Sankyo, Eisai, Eli Lilly, Janssen, Mitsubishi Tanabe, Novartis, Ono, Pfizer, Sanofi and Takeda, Grant/research support from: Asahi Kasei, Abbvie, Chugai, Eisai, Yves Schymura Employee of: Eli Lilly, Andrew Bradley Shareholder of: Eli Lilly, Employee of: Eli Lilly, Jens Gerwien Shareholder of: Eli Lilly, Employee of: Eli Lilly, Brigitte Monsberger Shareholder of: Eli Lilly, Employee of: Eli Lilly, Soyi Liu Leage Employee of: Eli Lilly, Daniel Aletaha Speakers bureau: Abbvie, Amgen, Celgene, Lilly, Medac, Merck, Novartis, Pfizer, Roche, Sandoz, Sanofi/Genzyme, Grant/research support from: Abbvie, Lilly, Novartis, Roche, Mikkel Østergaard Speakers bureau: Abbvie, Celgene, Eli-Lilly, Janssen, Novartis, Pfizer, Roche, Sanofi and UCB, Consultant of: Abbvie, BMS, Boehringer-Ingelheim, Celgene, Eli-Lilly, Hospira, Janssen, Merck, Novartis, Novo, Orion, Pfizer, Regeneron, Roche, Sandoz, Sanofi and UCB, Grant/research support from: Abbvie, BMS, Merck, Celgene, Novartis

Resolution acuity across the visual field for mesopic and scotopic illumination

We investigated the classical question of why visual acuity decreases with decreasing retinal illuminance by holding retinal eccentricity fixed while illumination varied. Our results indicate that acuity is largely independent of illuminance at any given retinal location, which suggests that under classical free-viewing conditions acuity improves as illumination increases from rod threshold to rod saturation because the retinal location of the stimulus is permitted to migrate from a peripheral location of maximum sensitivity but poor acuity to the foveal location of maximum acuity but poor sensitivity. Comparison with anatomical sampling density of retinal neurons suggests that mesopic acuity at all eccentricities and scotopic acuity for eccentricities beyond about 20° is limited by the spacing of midget ganglion cells. In central retina, however, scotopic acuity is further limited by spatial filtering due to spatial summation within the large, overlapping receptive fields of the A-II class of amacrine cells interposed in the rod pathway between rod bipolars and midget ganglion cells. Our results offer a mechanistic interpretation of the clinical metrics for low-luminance visual dysfunction used to monitor progression of retinal disease.

450 Retrospective Analysis of Surgical Clerk-Ins Within the Acute Receiving Unit: A Quality Improvement Project

Introduction

Accurate patient documentation at the ARU is vital to patient safety and ensuring smooth handovers to secondary care services. Because the nature of surgical treatment requires frequent patient handovers, and this increases the risk of miscommunication, we aimed to assess the quality of surgical clerk-ins and identify areas for improvement.

Method

Emergency admissions at the Dumfries Galloway Royal Infirmary were audited, looking at documentation quality under various clerk-in sections. Data was analysed before presentation to clinical governance.

Results

When 46 patient clerk-ins were examined, venous thromboembolism (VTE) prophylaxis plans were performed in only 24% of admissions - less than 1 in 4 patients.

Comparing out-of-hours and in-hours patient documentation, much higher omission rates were identified in the out-of-hours documentation: in systemic enquiry (42 vs 100%) and family history (31% vs 66%).

Conclusions

These results brought to attention the effect of hospital admission timing on patient documentation quality, and the lack of VTE prophylaxis planning. In surgery, these plans are key to minimising risk of avoidable thromboembolic complications.

A departmental meeting was convened to stress the importance of accurate and comprehensive clerk-ins to ARU doctors. Future audits could explore the factors influencing documentation quality for out-of-hours admissions, and ways to address these issues.

Time-course of the visual Impact on presbyopes of a low dose miotic

PURPOSE

To examine the pupil and visual impact of a single early morning drop of a low concentration miotic.

METHODS

Pupil size, refraction, visual acuity (VA), near reading performance and intraocular pressure were monitored for 8 h at a wide range of light levels following bilateral instillation of single drops of 0.1% brimonidine tartate in 19 early presbyopes (40-50 years) and 11 mature presbyopes (>50 years).

RESULTS

Pupil miosis did not alter distance VA or refraction. Significant pupil miosis peaked at 1-2 h after dosing, which expanded the depth of focus of mature presbyopes with the mean improvement in near logMAR VA of -0.15, -0.07 and -0.03, at 20, 200 and 2000 lux, respectively. One hour after instillation, near reading speed improved by 21, 24 and 5 words per min for text size commonly seen in US newspaper and cellphone text messages, 18, 21 and 19 words per min for text size of grocery labels and 12, 13 and 30 words per min for text size of over-the-counter medications at light levels of 20, 200 and 2000 lux, respectively. No such improvements in near VA and near reading speed were observed in the young presbyopes having some residual accommodation. Most of the pupil miosis remained 8 h after instillation, whereas near VA improvements disappeared after 4 h.

CONCLUSION

Low dose miotics can enhance near vision in presbyopic subjects while retaining high quality distance vision over a wide range of light levels. Significant improvements in near vision were observed only during the 1-2 h period after dosing when miosis peaked.

The Impact of IOL Abbe Number on Polychromatic Image Quality of Pseudophakic Eyes

Purpose

The human eye exhibits large amounts (2.5 diopters) of longitudinal chromatic aberration (LCA). Its impact on polychromatic image quality, however, has been shown experimentally and by computer modeling to be small or absent. We hypothesized that modest changes in pseudophakic LCA created by higher and lower Abbe number materials will have little or no impact on polychromatic image quality in pseudophakic eyes.

Materials and Methods

Using published chromatic and monochromatic aberration data from pseudophakic eyes and higher and lower Abbe number materials (37 and 55), we computed monochromatic point spread functions for 21 wavelengths across the visible spectrum. After weighting by either the RGB spectra of a liquid crystal display or by a flat white spectrum, they were weighted by the human spectral sensitivity function (V_λ) before being added to generate polychromatic PSFs.

Results

In the absence of monochromatic aberrations, the reduced LCA due to higher Abbe number intraocular lens (IOL) materials resulted in a reduction of 0.08 diopters in the mean defocus generated by LCA. At the retinal plane, the higher Abbe number pseudophakic model produced improvements in polychromatic modulation transfer functions (MTFs) similar to those generated by a 0.05 diopter reduction in spherical defocus. When monochromatic aberrations were added to make the model more representative of actual pseudophakic eyes, the differences in image quality became sub-threshold for human vision or disappeared completely.

Conclusion

The anticipated gains in polychromatic image quality from employing higher Abbe number IOL materials with reduced LCA do not materialize in plausible aberrated models of pseudophakic eyes.

Optical and imaging properties of a novel multi-segment spectacle lens designed to slow myopia progression

PURPOSE

High sampling density optical metrology combined with pupil- and image-plane numerical analyses were applied to evaluate a novel spectacle lens containing multiple small zones designed to slow myopia progression.

METHODS

High-resolution aberrometry (ClearWave, www.lumetrics.com) was used to sample wavefront slopes of a novel spectacle lens, Defocus Incorporated Multiple Segments (DIMS) (www.hoya.com), incorporating many small, positive-powered lenslets in its periphery. Using wavefront slope and error maps, custom MATLAB software ('Indiana Wavefront Analyzer') was used to compute image-plane point-spread functions (PSF), modulation transfer functions (MTF), simulated images and power distributions created by the dual-focus optic for different pupil sizes and target vergences.

RESULTS

Outside of a central 10 mm zone containing single distance optical power, a hexagonal array of small 1 mm lenslets with nearest-neighbour separations of 0.5 mm were distributed over the lens periphery. Sagittal and curvature-based measures of optical power imperfectly captured the consistent +3.50 D add produced by the lenslets. Image plane simulations revealed multiple PSFs and poor image quality at the lenslet focal plane. Blur at the distance optic focal plane was consistent with a combination of diffraction blur from the distance optic and the approximately +3.50 D of defocus from the 1 mm diameter near optic zones.

CONCLUSION

Converging the defocused beams generated by the multiple small (1 mm diameter) lenslets to a blurred image at the distance focal plane produced a blur magnitude determined by the small lenslet diameter and not the overall pupil diameter. The distance optic located in between the near-add lenslets determines the limits of the optical quality achievable by the lens. When compared to the optics of a traditional concentric-zone dual-focus contact lens, the optics of the DIMS lens generates higher-contrast images at low spatial frequencies (<7 cycles per degree), but lower-contrast at high spatial frequencies.

Experimental Model of Far Temporal Field Negative Dysphotopsia Generated in Phakic Eyes

Purpose

The axial separation between the iris and the intraocular lens (IOL) in pseudophakic eyes can cause rays originating from the far temporal field to miss the IOL, resulting in negative dysphotopsia (ND). We developed an experimental model to test the hypothesis that obstruction of rays from the far temporal field can generate ND and an accompanying loss of visual sensitivity in the far temporal field.

Methods

The right eyes of 10 phakic subjects were fitted with soft contact lenses containing a 5.50-mm central clear zone and a 12-mm outer diameter opaque annulus. In three of the subjects, eyes were dilated with 1% tropicamide solution, and effective aperture diameters were determined optically (pupil camera) and psychophysically (narrow beam detection). Visual field extent (Goldmann bowl) and temporal and inferotemporal meridian sensitivities (Octopus perimeter) were measured. A wide-angle model was constructed to quantify the impact of the annular opacity on retinal illuminance.

Results

All 10 subjects observed a dark crescent in the far temporal and inferotemporal fields. The opaque annulus reduced effective horizontal pupil diameters from 8 mm to 5.5 mm on-axis and from >2 mm to <1 mm at 90°. Perimetry revealed a 10° reduction in temporal and inferotemporal field extent and increasing loss of sensitivity beyond 70°. The wide-angle model confirmed significant vignetting (>50% beyond 70°), approaching zero retinal illuminance beyond 85°.

Conclusions

Vignetting of rays originating from the far temporal field by axially separated apertures can create symptoms mirroring perceptual reports of negative dysphotopsia in symptomatic pseudophakic patients.

Impact of monovision on dynamic accommodation of early presbyopes

PURPOSE

To examine the impact of monovision on dynamic changes in accommodation, pupil responses, spherical aberration and resultant image quality in early presbyopes.

METHODS

Refractive state, pupil size and spherical aberration levels were monitored in nine early presbyopes who exhibited some accommodation (40-50 years, mean = 42 ± 2.37 years) using a Shack-Hartmann aberrometer as a binocularly viewed stimulus stepped closer (from 2 m to 40 cm), or farther (from 40 cm to 2 m). Comparison data from two fully presbyopic (i.e. non-accommodating) subjects (ages 46 and 61 years) and two young adults (ages 26 and 29 years) were also collected. Each subject was fit with four different refractive strategies: (1) both eyes corrected for 2 m, (2) both eyes corrected for 40 cm, (3) monovision with the measured right eye corrected for 2 m and, (4) monovision with the right eye corrected for 40 cm. Monochromatic image quality was quantified using the AreaMTF metric.

RESULTS

When fit with monovision, the largest number of early presbyopes produce an accommodative response dominated by the right eye correction (distance or near) as the stimulus is abruptly changed from the retinal conjugate plane of one eye to that of the other eye. However, the accommodative responses in some early presbyopes were always dominated by the distance corrected eye, the near corrected eye, or by convergence. When the stimulus approached, the near corrected eye experienced high image quality only if there was no accommodative response. However, reduced image quality was observed if an accommodative response was initiated. Neither accommodation nor pupil response latencies were longer with monovision corrections compared with bilateral distance corrections (p > 0.05). In the early presbyopes, spherical aberration was reduced during near viewing, but primarily due to pupil miosis and not lens shape changes.

CONCLUSION

As the stimulus was abruptly changed from the retinal conjugate plane of the distance corrected eye to that of the near corrected eye, most early presbyopes fit with monovision accommodated, which resulted in a decline, not an increase in image quality in the near corrected eye. These results reveal a non-optimal accommodative strategy in early presbyopes fit with monovision.

Correction of presbyopia: old problems with old (and new) solutions

We live in a three-dimensional world and the human eye can focus images from a wide range of distances by adjusting the power of the eye's lens (accommodation). Progressive senescent changes in the lens ultimately lead to a complete loss of this ability by about age 50, which then requires alternative strategies to generate high-quality retinal images for far and close viewing distances. This review paper highlights the biomimetic properties and underlying optical mechanisms of induced anisometropia, small apertures, dynamic lenses, and multi-optic lenses in ameliorating the visual consequences of presbyopia. Specifically, the advantages and consequences of non-liner neural summation leveraged in monovision treatments are reviewed. Additionally, the value of a small pupil is quantified, and the impact of pinhole pupil location and their effects on neural sensitivity are examined. Different strategies of generating multifocal optics are also examined, and specifically the interaction between ocular and contact or intraocular lens aberrations and their effect on resulting image quality are simulated. Interestingly, most of the novel strategies for aiding presbyopic and pseudophakic eyes (for example, monovision, multifocality, pinhole pupils) have emerged naturally via evolution in a range of species.

Cross-sectional study of the prevalence, causes and management of hospital-onset diarrhoea

BACKGROUND

The National Health Service in England advises hospitals collect data on hospital-onset diarrhoea (HOD). Contemporaneous data on HOD are lacking.

AIM

To investigate prevalence, aetiology and management of HOD on medical, surgical and elderly-care wards.

METHODS

A cross-sectional study in a volunteer sample of UK hospitals, which collected data on one winter and one summer day in 2016. Patients admitted ≥72 h were screened for HOD (definition: ≥2 episodes of Bristol Stool Type 5-7 the day before the study, with diarrhoea onset >48 h after admission). Data on HOD aetiology and management were collected prospectively.

FINDINGS

Data were collected on 141 wards in 32 hospitals (16 acute, 16 teaching). Point-prevalence of HOD was 4.5% (230/5142 patients; 95% confidence interval (CI) 3.9-5.0%). Teaching hospital HOD prevalence (5.9%, 95% CI 5.1-6.9%) was twice that of acute hospitals (2.8%, 95% CI 2.1-3.5%; odds ratio 2.2, 95% CI 1.7-3.0). At least one potential cause was identified in 222/230 patients (97%): 107 (47%) had a relevant underlying condition, 125 (54%) were taking antimicrobials, and 195 (85%) other medication known to cause diarrhoea. Nine of 75 tested patients were Clostridium difficile toxin positive (4%). Eighty (35%) patients had a documented medical assessment of diarrhoea. Documentation of HOD in medical notes correlated with testing for C. difficile (78% of those tested vs 38% not tested, P<0.001). One-hundred and forty-four (63%) patients were not isolated following diarrhoea onset.

CONCLUSION

HOD is a prevalent symptom affecting thousands of patients across the UK health system each day. Most patients had multiple potential causes of HOD, mainly iatrogenic, but only a third had medical assessment. Most were not tested for C. difficile and were not isolated.

IMI - Clinical Myopia Control Trials and Instrumentation Report

The evidence-basis based on existing myopia control trials along with the supporting academic literature were reviewed; this informed recommendations on the outcomes suggested from clinical trials aimed at slowing myopia progression to show the effectiveness of treatments and the impact on patients. These outcomes were classified as primary (refractive error and/or axial length), secondary (patient reported outcomes and treatment compliance), and exploratory (peripheral refraction, accommodative changes, ocular alignment, pupil size, outdoor activity/lighting levels, anterior and posterior segment imaging, and tissue biomechanics). The currently available instrumentation, which the literature has shown to best achieve the primary and secondary outcomes, was reviewed and critiqued. Issues relating to study design and patient selection were also identified. These findings and consensus from the International Myopia Institute members led to final recommendations to inform future instrumentation development and to guide clinical trial protocols.

Health assessments and screening tools for adults experiencing homelessness: a systematic review

Background

Homelessness is increasing globally. It results in poorer physical and mental health than age matched people living in permanent housing. Better information on the health needs of people experiencing homelessness is needed to inform effective resourcing, planning and service delivery by government and care organisations.

The aim of this review was to identify assessment tools that are valid, reliable and appropriate to measure the health status of people who are homeless.

Methods

Data sources: A systematic literature search was conducted in PubMed (and Medline), PsychInfo, Scopus, CINAHL and ERIC from database inception until September 2018. Key words used were homeless, homelessness, homeless persons, vagrancy, health status, health, health issues, health assessment and health screening. The protocol was registered with PROSPERO. The National Health and Medical Research Council of Australia (NHMRC) hierarchy of evidence was applied; methodological quality of included articles was assessed using the McMaster critical appraisal tools and psychometric properties of the tools were appraised using the International Centre for Allied Health Evidence Ready Reckoner.

Results

Diverse tools and measures (N = 71) were administered within, and across the reviewed studies (N = 37), with the main focus being on general health, oral health and nutrition. Eleven assessment tools in 13 studies had evidence of appropriate psychometric testing for the target population in domains of quality of life and health status, injury, substance use, mental health, psychological and cognitive function. Methodological quality of articles and tools were assessed as moderate to good. No validated tools were identified to assess oral health, chronic conditions, anthropometry, demography, nutrition, continence, functional decline and frailty, or vision and hearing. However, assessments of physical constructs (such as oral health, anthropometry, vision and hearing) could be applied to homeless people on a presumption of validity, because the constructs would be measured with clinical indicators in the same manner as people living in permanent dwellings.

Conclusions

This review highlighted the need to develop consistent and comprehensive health assessment tools validated with, and tailored for, adults experiencing homelessness.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7234-y) contains supplementary material, which is available to authorized users.

Ricco's law and absolute threshold for foveal detection of black holes

Visual detection of small black objects surrounded by a light background depends on background luminance, pupil size, optical blur, and object size. Holding pupil and optics fixed, we measured the minimum background luminance needed for foveal detection of small black targets as a function of target size. For all three observers, absolute threshold varied inversely with target area when disk diameter subtended less than 10^' of visual angle. For target diameter ≥10^', threshold remained constant at about 0.3 Td, which was also the absolute threshold for detecting light spots 10^' or larger in diameter on a black background. These results are consistent with Ricco's law of spatial summation: a "black hole" is just detectable when the background luminance is sufficiently high for its absence inside the Ricco area to reduce 555 nm photon flux by 7500 photons/s, which is the same change needed to detect light spots on a black surround. These results can be accounted for by a differential pair of Ricco detectors, each about the size of the receptive field center of magocellular retinal ganglion cells when projected into object space through the eye's weakly aberrated optical system. Statistical analysis of the model suggests the quantum fluctuations due to internal, biological noise (i.e., "scotons") are a greater handicap than the photon fluctuations inherent in the light stimulus at absolute foveal threshold.

Psychophysical study of the optical origin of starbursts

Starbursts seen around small bright lights at night have been attributed to optical scatter, diffraction, or aberrations. We manipulated pupil aperture and aberrations to investigate the entopic appearance of perceived starbursts. The impact of circular, annular, and wedge-shaped pupil apertures, and spherical aberration sign and magnitude were used to identify pupil sub-apertures responsible for each radial perceived starburst line. Local intensity distributions within the starbursts mapped onto unique sub-regions of the pupil of both phakic and pseudophakic eyes, consistent with the hypothesis that ocular aberrations are the cause of starbursts. In paraxially focused eyes, the size of starbursts is predicted by the amount of spherical aberration, and starburst orientation is either the same or 180 deg rotated from the pupil region that creates each starburst line. No starbursts are seen when the pupil diameter is smaller than 3 mm. Replacing the eye's natural lens with a radially symmetric and optically homogeneous intraocular lens reduced the observed number of starbursts by 50%. Geometrical optics modeling including the measured aberrations of an individual eye can reveal point spread function structure that captures some of the key elements of the entopic perceptions.

Aging phenotype(s) in kidneys of diabetic mice are p66ShcA dependent

The p66ShcA protein controls cellular responses to oxidative stress, senescence, and apoptosis. Here, we test the hypothesis that aging phenotype(s) commonly associated with the broad category of chronic kidney disease are accelerated in diabetic kidneys and linked to the p66ShcA locus. At the organ level, tissue stem cells antagonize senescent phenotypes by replacing old dysfunctional cells. Using established methods, we isolated a highly purified population of stem cell antigen-1-positive mesenchymal stem cells (Sca-1⁺ MSCs) from kidneys of wild-type (WT) and p66 knockout (p66 KO) mice. Cells were plated in culture medium containing normal glucose (NG) or high glucose (HG). Reactive oxygen species (ROS) metabolism was substantially increased in WT MSCs in HG medium in association with increased cell death by apoptosis and acquisition of the senescent phenotype. DNA microarray analysis detected striking differences in the expression profiles of WT and p66 KO-MSCs in HG medium. Unexpectedly, the analysis for p66 KO-MSCs revealed upregulation of Wnt genes implicated in self-renewal and differentiation. To test the in vivo consequences of constitutive p66 expression in diabetic kidneys, we crossed the Akita diabetic mouse with the p66KO mouse. Homozygous mutation at the p66 locus delays or prevents aging phenotype(s) in the kidney that may be precursors to diabetic nephropathy.

Multiple traumatisation and subsequent psychopathology in people with intellectual disabilities and DSM-5 PTSD: a preliminary study

BACKGROUND

Individuals with intellectual disability (ID) are at greater risk of exposure to traumatic life events compared with the non-ID population. Yet no study to date has examined the role of multiple traumatisation and subsequent psychopathology in people with ID. The aim of this study was to explore the association between multiple traumatisation and subsequent mental health.

METHODS

A preliminary cross-sectional study involving 33 participants with DSM-5 post-traumatic stress disorder completed self-report questionnaires on exposure to traumatic life events and post-traumatic stress disorder symptoms, anxiety, depression and general distress.

RESULTS

A proportion of 42.4% of the sample reported multiple traumatisation, including exposure to life events in both childhood and adulthood. Those who reported exposure to life events in childhood and adulthood reported significantly higher risk of harm, depression and general psychological distress compared with those who reported exposure to life events only in adulthood.

CONCLUSIONS

Preliminary results indicate that more severe psychopathology is associated with multiple traumatisation in childhood and adulthood compared with trauma experienced solely in adulthood.

The effect of spherical aberration on visual performance and refractive state for stimuli and tasks typical of night viewing

PURPOSE

The aim of this work was to examine the impact of Seidel spherical aberration (SA) on optimum refractive state for detecting and discriminating small bright lights on a dark background.

METHODS

An adaptive-optics system was used to correct ocular aberrations of cyclopleged eyes and then systematically introduce five levels of Seidel SA for a 7-mm diameter pupil: 0,±0.18, and±0.36diopters (D)mm-2. For each level of SA, subjects were required to detect one or resolve two points of light (0.54 arc min diameter) on a dark background. Refractive error was measured by adjusting stimulus vergence to minimize detection and resolution thresholds. Two other novel focusing tasks for single points of light required maximizing the perceived intensity of a bright point's core and minimizing its overall perceived size (i.e. minimize starburst artifacts). Except for the detection task, luminance of the point of light was 1000cdm-2 on a black background lower than 0.5cdm-2.

RESULTS

Positive SA introduced myopic shifts relative to the best subjective focus for dark letters on a bright background when there was no SA, whereas negative SA introduced hyperopic shifts in optimal focus. The changes in optimal focus were -1.7, -2.4, -2.0, and -9.2D of focus per Dmm-2 of SA for the detection task, resolution task, and maximization of core's intensity and minimization of size, respectively.

CONCLUSION

Ocular SA can be a significant contributor to changes in refractive state when viewing high-contrast point sources typically encountered in nighttime environments.

What is a troland?

Trolands are a widely used measure of retinal illuminance in vision science and visual optics, but disagreements exist for the definition and interpretation of this photometric unit. The purpose of this communication is to resolve the confusion by providing a sound conceptual basis for interpreting trolands as a measure of angular flux density incident upon the retina. Using a simplified optical analysis, we show that the troland value of an extended source is the intensity in micro-candelas of an equivalent point source located at the eye's posterior nodal point that produces the same illuminance in the retinal image as does the extended source. This optical interpretation of trolands reveals that total light flux in the image of an extended object is the product of the troland value of the source and the solid angle subtended by the source at the first nodal point, independent of eye size.

Simulation of a central scotoma using contact lenses with an opaque centre

PURPOSE

This study evaluated the feasibility of using soft contact lenses (CLs) with an opaque centre to induce absolute central scotomas that move with the eye. We examined the geometrical optics prediction that scotoma size will vary with the size of the CL's opaque centre and with ocular pupil size. We also tested the hypothesis that high environmental light levels will ensure that the ocular pupil will remain small enough, even with opaque centre CLs, to generate absolute scotomas representative of those experienced by patients with age-related macular disease.

METHODS

Using an Octopus 900 Perimeter ( www.Haag-Streit.com), kinetic visual fields (VFs) were measured in five normally-sighted subjects using a V4e Goldmann target with CLs that had central opaque areas with diameters of 2.8, 3.0, and 3.2 mm. To control pupil size, VFs were measured with background perimeter bowl luminances of 10, 585, and 1155 cd m^-2 . Subjects attempted to (i) fixate the bowl centre; and (ii) place the scotoma edge at the bowl fixation target (eccentric viewing).

RESULTS

As predicted, there was a direct relationship between scotoma size and both luminance level and diameter of the opacity. Mean scotoma diameters were 0°, 17.6° and 22°, for the low, medium and high bowl luminances, respectively. Scotoma size was determined primarily by the difference between the diameters of CL opacity and the entrance pupil of the eye and the axial separation between them, and between-subject differences in pupil diameters contributed most to the between-subject variability in scotoma diameter at each light level (SD: 6.01°). Scotoma displacement during eccentric fixation confirmed the gaze-contingent characteristics of this experimental model.

CONCLUSION

It is possible to induce a gaze-contingent absolute scotoma and hence mimic central vision loss using centrally-opaque CLs provided that the CL opacity is larger than the entrance pupil of the eye. This simulation tool will, therefore, be ineffective at low environmental light levels (as shown previously) if the entrance pupil of the eye is larger than the CL opacity.

Reducing starbursts in highly aberrated eyes with pupil miosis

PURPOSE

To test the hypothesis that marginal ray deviations determine perceived starburst sizes, and to explore different strategies for decreasing starburst size in highly aberrated eyes.

METHODS

Perceived size of starburst images and visual acuities were measured psychophysically for eyes with varying levels of spherical aberration, pupil sizes, and defocus. Computationally, we use a polychromatic eye model including the typical levels of higher order aberrations (HOAs) for keratoconic and post-LASIK eyes to quantify the image quality (the visually weighted Strehl ratio derived from the optical transfer function, VSOTF) with different pupil sizes at both photopic and mesopic light levels.

RESULTS

For distance corrected post-LASIK and keratoconic eyes with a night-time pupil (e.g., 7 mm), the starburst diameter is about 1.5 degrees (1 degree for normal presbyopic eyes), which can be reduced to ≤0.25 degrees with pupil sizes ≤3 mm. Starburst size is predicted from the magnitude of the longitudinal spherical aberration. Refracting the eye to focus the pupil margin also removed starbursts, but, unlike small pupils, significantly degraded visual acuity. Reducing pupil diameter to 3 mm improved image quality for these highly aberrated eyes by about 2.7 ×  to 1.7 ×  relative to the natural pupils when light levels were varied from 0.1 to 1000 cd m^-2 , respectively.

CONCLUSION

Subjects with highly aberrated eyes observed larger starbursts around bright lights at night predictable by the deviated marginal rays. These were effectively attenuated by reducing pupil diameters to ≤3 mm, which did not cause a drop in visual acuity or modelled image quality even at mesopic light levels.

The Effect of Light Level and Small Pupils on Presbyopic Reading Performance

Purpose

To examine the impact of small pupils and light levels on reading performance of distance-corrected presbyopes. To determine whether small pupils would enable presbyopes to read at near even at low light levels.

Methods

To establish the lower range of text luminances, we quantified the space-averaged luminance of text in nine different artificially lit interior environments, and examined the impact of the text characters on space-averaged luminance of electronic and printed displays. Distance and near reading speeds of 20 presbyopes (ages 40-60 years) were measured while viewing through artificial pupils (diameters 1-4.5 mm), natural pupils, or with a multifocal contact lens. Space-averaged text luminance levels varied from 0.14 to 140 cd/m2 (including the range of measured environmental text luminances).

Results

Adding black text to a white computer display or paper reduces luminance by approximately 15% to 31%, and the lowest encountered environmental text luminance was approximately 2 to 3 cd/m2. For both distance and near reading performance, the 2- to 3-mm small pupil yielded the best overall reading acuity for space-averaged text light levels ≥ 2 cd/m2. The 2- to 3-mm artificial pupils and the multifocal contact lenses both enabled maximum or near-maximum reading speeds for 0.5 logMAR characters at distance and near, but with natural pupils, reading speeds were significantly reduced at near.

Conclusions

Although photon noise at low luminance reduces the visual benefits of small pupils, the benefits of 2- to 3-mm artificial pupils are sufficient to enable >80% of distance-corrected presbyopes to read proficiently at near, even at the lowest text luminances found in interior environments.

Interaction of aberrations, diffraction, and quantal fluctuations determine the impact of pupil size on visual quality

Our purpose is to develop a computational approach that jointly assesses the impact of stimulus luminance and pupil size on visual quality. We compared traditional optical measures of image quality and those that incorporate the impact of retinal illuminance dependent neural contrast sensitivity. Visually weighted image quality was calculated for a presbyopic model eye with representative levels of chromatic and monochromatic aberrations as pupil diameter was varied from 7 to 1 mm, stimulus luminance varied from 2000 to 0.1  cd/m², and defocus varied from 0 to -2 diopters. The model included the effects of quantal fluctuations on neural contrast sensitivity. We tested the model's predictions for five cycles per degree gratings by measuring contrast sensitivity at 5  cyc/deg. Unlike the traditional Strehl ratio and the visually weighted area under the modulation transfer function, the visual Strehl ratio derived from the optical transfer function was able to capture the combined impact of optics and quantal noise on visual quality. In a well-focused eye, provided retinal illuminance is held constant as pupil size varies, visual image quality scales approximately as the square root of illuminance because of quantum fluctuations, but optimum pupil size is essentially independent of retinal illuminance and quantum fluctuations. Conversely, when stimulus luminance is held constant (and therefore illuminance varies with pupil size), optimum pupil size increases as luminance decreases, thereby compensating partially for increased quantum fluctuations. However, in the presence of -1 and -2 diopters of defocus and at high photopic levels where Weber's law operates, optical aberrations and diffraction dominate image quality and pupil optimization. Similar behavior was observed in human observers viewing sinusoidal gratings. Optimum pupil size increases as stimulus luminance drops for the well-focused eye, and the benefits of small pupils for improving defocused image quality remain throughout the photopic and mesopic ranges. However, restricting pupils to <2  mm will cause significant reductions in the best focus vision at low photopic and mesopic luminances.