Differential impact of COVID-19 on mental health and burnout

BACKGROUND

There may be differential impact of the COVID-19 pandemic on mental health and burnout rates of healthcare professionals (HCPs) performing different roles.

AIMS

To examine mental health and burnout rates, and possible drivers for any disparities between professional roles.

METHODS

In this cohort study, online surveys were distributed to HCPs in July-September 2020 (baseline) and re-sent 4 months later (follow-up; December 2020) assessing for probable major depressive disorder (MDD), generalized anxiety disorder (GAD), insomnia, mental well-being and burnout (emotional exhaustion and depersonalization). Separate logistic regression models (at both phases) compared the risk of outcomes between roles: healthcare assistants (HCAs), nurses and midwives (nurses), allied health professionals (AHPs) and doctors (reference group). Separate linear regression models were also developed relating the change in scores to professional role.

RESULTS

At baseline (n = 1537), nurses had a 1.9-fold and 2.5-fold increased risk of MDD and insomnia, respectively. AHPs had a 1.7-fold and 1.4-fold increased risk of MDD and emotional exhaustion, respectively. At follow-up (n = 736), the disproportionate risk between doctors and others worsened: nurses and HCAs were at 3.7-fold and 3.6-fold increased risk of insomnia, respectively. Nurses also had a significantly increased risk of MDD, GAD, poor mental well-being and burnout. Nurses also had significantly worsened anxiety, mental well-being and burnout scores over time, relative to doctors.

CONCLUSIONS

Nurses and AHPs had excess risk of adverse mental health and burnout during the pandemic, and this difference worsened over time (in nurses especially). Our findings support adoption of targeted strategies accounting for different HCP roles.

Spontaneous Early Intraprosthetic Dislocation of 22 mm Skirted Femoral Head in Dual Mobility Hip Prosthesis: A Case Report

Introduction:

There is a trend for increasing use of dual mobility hip designs for both primary and revision hip arthroplasty settings. It provides dual articular surfaces along with increased jump distance to increase the stability of construct. However, this design has some unique complications of its own which surgeons should be aware of especially intraprosthetic dislocation (IPD).

Case Report:

A 76-year-old lady presented to clinic with painful hip hemiarthroplasty after fracture neck of femur. She underwent revision surgery with dual mobility uncemented acetabular cup and femoral stem was retained as it was well fixed. She was mobilizing well and around 5 weeks post her surgery, developed pain in hip region and difficulty in weight-bearing. Radiographs showed eccentric position of femoral neck in the socket. A diagnosis of IPD was established and revision surgery was planned. Intraoperatively, metal head had dislocated from the polyethylene head and both components were resting in the acetabular socket. No macroscopic erosion of acetabulum was noticed. The polyethylene component and femoral head were retrieved. With previous failed dual mobility, decision was made to achieve stability with larger head size and lipped liner posteriorly.

Conclusion:

IPD is a rare occurrence and unique complication to dual mobility implants. This report highlights that patients can have IPD without fall or trauma.

Bone metastases of the hand

Introduction The aim of this study was to identify patients with malignant hand lesions, establish the proportions of those that were metastases and review their clinical course. Methods A retrospective search of a prospective tumour database was carried out to identify all patients treated at our unit with hand metastases. Patient demographics were recorded including site of primary malignancy, region of the hand involved, management of their metastasis and clinical outcome. Results Overall, 149 patients were identified with a malignant tumour of the hand. Ten had a metastatic lesion. There were 3 women and 7 men with a median age of 68 years (range: 28-91 years) at presentation. All presented with non-mechanical hand pain while four had pain and swelling. The median interval from symptom onset to diagnosis was eight weeks. The minimum follow-up duration was four months. Three patients had no history of malignancy. Of the remaining seven patients, three had other known metastases. Six patients underwent solely palliative radiotherapy. Three patients had amputation. One was treated with surgical excision and radiotherapy. One had an amputation and axillary node clearance. All but one patient had died by the time of the latest follow-up appointment. The median time to death following identification of acrometastases was 18 months. Sites of primary disease were skin (n=4), lung (n=3), kidney (n=2) and neuroendocrine system (n=1). The thumb was the most commonly affected location. Conclusions This study demonstrates that patients presenting with non-mechanical hand pain should be considered to have a malignant process until proved otherwise, particularly in patients with thumb symptoms and a history of prior malignancy.

Megaprostheses in the management of trauma of the knee

OBJECTIVE

Review the outcome of patients with complex fractures around the knee treated with megaprosthesis.

METHOD

Retrospective observational study of 10 patients was undertaken.

RESULTS

Six patients were treated with a distal femoral endoprosthesis (DEFPR) and four with an augmented rotating hinge knee replacement (RHK). The mean post-operative Toronto Extremity Salvage Score (TESS) was 62.5 for the whole cohort (RHK group 79.3, compared with 49.2 in the DFEPR group (p = 0.038), peri-prosthetic fracture group was 46.3, compared with 75.6 in native knee fracture group (p = 0.04)).

CONCLUSION

A megaprosthesis is a viable option in complex fractures around the knee.

Midwall Fibrosis: Cardiac Magnetic Resonance Imaging in Risk Stratifying Cardiomyopathies

The United Kingdom’s National Institute for Health and Care Excellence guidance on implantable cardiac defibrillator (ICD) therapy recommend ICD in those with left ventricular dysfunction and a high risk of sudden cardiac death (SCD). SCD accounts for 30% deaths in non-ischaemic dilated cardiomyopathy (DCM), however risk stratifying and predicting SCD in DCM is a major management challenge. We present two cases demonstrating the potential role of cardiac magnetic resonance imaging in risk stratifying DCM.

Extra-hepatic manifestations of autochthonous hepatitis E infection

BACKGROUND

Autochthonous (locally acquired) hepatitis E is increasingly recognised in developed countries, and is thought to be a porcine zoonosis. A range of extra-hepatic manifestations of hepatitis E infection have been described, but have never been systematically studied.

AIM

To report the extra-hepatic manifestations of hepatitis E virus.

METHODS

Retrospective review of data of 106 cases of autochthonous hepatitis E (acute n = 105, chronic n = 1).

RESULTS

Eight (7.5%) cases presented with neurological syndromes, which included brachial neuritis, Guillain-Barré syndrome, peripheral neuropathy, neuromyopathy and vestibular neuritis. Patients with neurological syndromes were younger (median age 40 years, range 34-92 years, P = 0.048) and had a more modest transaminitis (median ALT 471 IU/L, P = 0.015) compared to cases without neurological symptoms [median age 64 years (range 18-88 years), median ALT 1135 IU/L]. One patient presented with a cardiac arrhythmia,twelve patients (11.3%) presented with thrombocytopenia, fourteen (13.2%) with lymphocytosis and eight (7.5%) with a lymphopenia, none of which had any clinical consequence. Serum electrophoresis was performed in 65 patients at presentation, of whom 17 (26%) had a monoclonal gammopathy of uncertain significance. Two cases developed haematological malignancies, acute myeloid leukaemia and duodenal plasmacytoma, 18 and 36 months after presenting with acute hepatitis E infection.

CONCLUSIONS

A range of extra-hepatic manifestations can occur with hepatitis E. Neurological and haematological features of hepatitis E infection are relatively frequent in this UK cohort, and result in significant morbidity which warrants further study.

Surveillance for ocular hypertension: an evidence synthesis and economic evaluation

OBJECTIVES

To determine effective and efficient monitoring criteria for ocular hypertension [raised intraocular pressure (IOP)] through (i) identification and validation of glaucoma risk prediction models; and (ii) development of models to determine optimal surveillance pathways.

DESIGN

A discrete event simulation economic modelling evaluation. Data from systematic reviews of risk prediction models and agreement between tonometers, secondary analyses of existing datasets (to validate identified risk models and determine optimal monitoring criteria) and public preferences were used to structure and populate the economic model.

SETTING

Primary and secondary care.

PARTICIPANTS

Adults with ocular hypertension (IOP > 21 mmHg) and the public (surveillance preferences).

INTERVENTIONS

We compared five pathways: two based on National Institute for Health and Clinical Excellence (NICE) guidelines with monitoring interval and treatment depending on initial risk stratification, 'NICE intensive' (4-monthly to annual monitoring) and 'NICE conservative' (6-monthly to biennial monitoring); two pathways, differing in location (hospital and community), with monitoring biennially and treatment initiated for a ≥ 6% 5-year glaucoma risk; and a 'treat all' pathway involving treatment with a prostaglandin analogue if IOP > 21 mmHg and IOP measured annually in the community.

MAIN OUTCOME MEASURES

Glaucoma cases detected; tonometer agreement; public preferences; costs; willingness to pay and quality-adjusted life-years (QALYs).

RESULTS

The best available glaucoma risk prediction model estimated the 5-year risk based on age and ocular predictors (IOP, central corneal thickness, optic nerve damage and index of visual field status). Taking the average of two IOP readings, by tonometry, true change was detected at two years. Sizeable measurement variability was noted between tonometers. There was a general public preference for monitoring; good communication and understanding of the process predicted service value. 'Treat all' was the least costly and 'NICE intensive' the most costly pathway. Biennial monitoring reduced the number of cases of glaucoma conversion compared with a 'treat all' pathway and provided more QALYs, but the incremental cost-effectiveness ratio (ICER) was considerably more than £30,000. The 'NICE intensive' pathway also avoided glaucoma conversion, but NICE-based pathways were either dominated (more costly and less effective) by biennial hospital monitoring or had a ICERs > £30,000. Results were not sensitive to the risk threshold for initiating surveillance but were sensitive to the risk threshold for initiating treatment, NHS costs and treatment adherence.

LIMITATIONS

Optimal monitoring intervals were based on IOP data. There were insufficient data to determine the optimal frequency of measurement of the visual field or optic nerve head for identification of glaucoma. The economic modelling took a 20-year time horizon which may be insufficient to capture long-term benefits. Sensitivity analyses may not fully capture the uncertainty surrounding parameter estimates.

CONCLUSIONS

For confirmed ocular hypertension, findings suggest that there is no clear benefit from intensive monitoring. Consideration of the patient experience is important. A cohort study is recommended to provide data to refine the glaucoma risk prediction model, determine the optimum type and frequency of serial glaucoma tests and estimate costs and patient preferences for monitoring and treatment.

FUNDING

The National Institute for Health Research Health Technology Assessment Programme.

Multiple component patient safety intervention in English hospitals: controlled evaluation of second phase

OBJECTIVE

To independently evaluate the impact of the second phase of the Health Foundation's Safer Patients Initiative (SPI2) on a range of patient safety measures. Design A controlled before and after design. Five substudies: survey of staff attitudes; review of case notes from high risk (respiratory) patients in medical wards; review of case notes from surgical patients; indirect evaluation of hand hygiene by measuring hospital use of handwashing materials; measurement of outcomes (adverse events, mortality among high risk patients admitted to medical wards, patients' satisfaction, mortality in intensive care, rates of hospital acquired infection). Setting NHS hospitals in England.

PARTICIPANTS

Nine hospitals participating in SPI2 and nine matched control hospitals.

INTERVENTION

The SPI2 intervention was similar to the SPI1, with somewhat modified goals, a slightly longer intervention period, and a smaller budget per hospital.

RESULTS

One of the scores (organisational climate) showed a significant (P = 0.009) difference in rate of change over time, which favoured the control hospitals, though the difference was only 0.07 points on a five point scale. Results of the explicit case note reviews of high risk medical patients showed that certain practices improved over time in both control and SPI2 hospitals (and none deteriorated), but there were no significant differences between control and SPI2 hospitals. Monitoring of vital signs improved across control and SPI2 sites. This temporal effect was significant for monitoring the respiratory rate at both the six hour (adjusted odds ratio 2.1, 99% confidence interval 1.0 to 4.3; P = 0.010) and 12 hour (2.4, 1.1 to 5.0; P = 0.002) periods after admission. There was no significant effect of SPI for any of the measures of vital signs. Use of a recommended system for scoring the severity of pneumonia improved from 1.9% (1/52) to 21.4% (12/56) of control and from 2.0% (1/50) to 41.7% (25/60) of SPI2 patients. This temporal change was significant (7.3, 1.4 to 37.7; P = 0.002), but the difference in difference was not significant (2.1, 0.4 to 11.1; P = 0.236). There were no notable or significant changes in the pattern of prescribing errors, either over time or between control and SPI2 hospitals. Two items of medical history taking (exercise tolerance and occupation) showed significant improvement over time, across both control and SPI2 hospitals, but no additional SPI2 effect. The holistic review showed no significant changes in error rates either over time or between control and SPI2 hospitals. The explicit case note review of perioperative care showed that adherence rates for two of the four perioperative standards targeted by SPI2 were already good at baseline, exceeding 94% for antibiotic prophylaxis and 98% for deep vein thrombosis prophylaxis. Intraoperative monitoring of temperature improved over time in both groups, but this was not significant (1.8, 0.4 to 7.6; P = 0.279), and there were no additional effects of SPI2. A dramatic rise in consumption of soap and alcohol hand rub was similar in control and SPI2 hospitals (P = 0.760 and P = 0.889, respectively), as was the corresponding decrease in rates of Clostridium difficile and meticillin resistant Staphylococcus aureus infection (P = 0.652 and P = 0.693, respectively). Mortality rates of medical patients included in the case note reviews in control hospitals increased from 17.3% (42/243) to 21.4% (24/112), while in SPI2 hospitals they fell from 10.3% (24/233) to 6.1% (7/114) (P = 0.043). Fewer than 8% of deaths were classed as avoidable; changes in proportions could not explain the divergence of overall death rates between control and SPI2 hospitals. There was no significant difference in the rate of change in mortality in intensive care. Patients' satisfaction improved in both control and SPI2 hospitals on all dimensions, but again there were no significant changes between the two groups of hospitals.

CONCLUSIONS

Many aspects of care are already good or improving across the NHS in England, suggesting considerable improvements in quality across the board. These improvements are probably due to contemporaneous policy activities relating to patient safety, including those with features similar to the SPI, and the emergence of professional consensus on some clinical processes. This phenomenon might have attenuated the incremental effect of the SPI, making it difficult to detect. Alternatively, the full impact of the SPI might be observable only in the longer term. The conclusion of this study could have been different if concurrent controls had not been used.

Development of a competency framework for optometrists with a specialist interest in glaucoma

PURPOSE

To develop a competency framework, using a modified Delphi methodology, for optometrists with a specialist interest in glaucoma, which would provide a basis for training and accreditation.

METHODS

A modified iterative Delphi technique was used using a 16-member panel consisting almost exclusively of sub-specialist optometrists and ophthalmologists. The first round involved scoring the relevance of a draft series of competencies using a 9-point Likert scale with a free-text option to modify any competency or suggest additional competencies. The revised framework was subjected to a second round of scoring and free-text comment. The Delphi process was followed by a face-to-face structured workshop to debate and agree the final framework. The version of the framework agreed at the workshop was sent out for a 4-month period of external stakeholder validation.

RESULTS

There was a 100% response to round 1 and an 94% response to round 2. All panel members attended the workshop. The final version of the competency framework was validated by a subsequent stakeholder consultation and contained 19 competencies for the diagnosis of glaucoma and 7 further competencies for monitoring and treatment.

CONCLUSIONS

Application of a consensus methodology consisting of a modified Delphi technique allowed the development of a competency framework for glaucoma specialisation by optometrists. This will help to shape the development of a speciality curriculum and potentially could be adapted for other healthcare professionals.

Treatment of scaphoid nonunion with combined vascularized distal radius graft and iliac crest bone graft

The optimal treatment of scaphoid nonunion is a controversial and challenging task in hand surgery. Although advances in internal fixation techniques have resulted in improved union rates, fractures with impaired vascularity have less than satisfactory results with conventional grafting techniques. We describe the technique of using a tricortical iliac crest graft and a vascularized distal radius graft in cases of nonunion with avascular necrosis. The principle of our technique is to improve union rates over previously described procedures by addressing the issues of stability using a tricortical graft with compression through internal fixation and by improving biology using a cancellous vascularized graft.

A review of retraction pockets: past, present and future management

Retraction pockets can lead to hearing loss and cholesteatoma. Distinguishing stable from progressive disease is challenging to any otologist. The management of retraction pockets is a contentious issue with present treatment options often plagued with recurrence. The purpose of this article is to summarize recent developments in the aetiology of retraction pockets of the pars tensa, its diagnostic and management problems and to define possible future therapeutic options.

Age-related changes in the thickness of the human lamina cribrosa

OBJECTIVE

To measure the human lamina cribrosa thickness (LCT) in vitro in fully hydrated specimens and to determine whether there is any association between thickness and age or sex.

METHODS

45 fixed human optic nerves, age range 9-90 years, were dissected from the globe and frozen sectioned. The study was divided into two parts: the first investigated the overall change in LCT and cribrosal beam thickness (CBT) with age, and the second divided eyes into two specific age groups (38-49 and 78-87 years) and assessed differences with respect to age and sex.

RESULTS

LCT ranged from 345.4 to 555.9 microm between the samples. A positive relationship was found between LCT and age (LCT = 2.41xage+365.5, 95% confidence interval (CI) for slope 1.31 to 3.52; r(2) = 0.30, p<0.001). A regional difference in CBT was observed, with beams being thickest at the posterior cribrosa (mean 14.8 (standard deviation (SD) 2.2) microm) and thinnest at the anterior cribrosa (9.8 (SD 2.4) microm). CBT increased with increasing age. Differences related to sex were also found, with females having relatively thinner LCT than males, irrespective of age, but this was not statistically significant.

CONCLUSIONS

This study shows an increase in human LCT with increasing age. This changing structural property of the lamina cribrosa may have implications for its functioning with respect to compliance and reversibility, and has particular relevance to glaucoma, where increasing age has been identified as a strong risk factor for the development of the disease.

The relative effects of corneal thickness and age on Goldmann applanation tonometry and dynamic contour tonometry

AIMS

To establish the effects of central corneal thickness (CCT) on intraocular pressure (IOP) measured with a prototype Pascal dynamic contour tonometer (DCT), to evaluate the effect of CCT and age on the agreement between IOP measured with the Pascal DCT and Goldmann applanation tonometer (GAT), and to compare the interobserver and intraobserver variation of the DCT with the GAT.

METHODS

GAT and DCT IOP measurements were made on 130 eyes of 130 patients and agreement was assessed by means of Bland-Altman plots. The effect of CCT and age on GAT/DCT IOP differences was assessed by linear regression analysis. Interobserver and intraobserver variations for GAT and DCT were assessed in 100 eyes of 100 patients.

RESULTS

The mean difference (95% limits of agreement) between GAT and DCT was -0.7 (-6.3 to 4.9) mm Hg. GAT/DCT IOP differences increased with thicker CCT (slope 0.017 mm Hg/microm, 95% CI 0.004 to 0.03, r2 = 0.05, p = 0.01), and with greater age, slope 0.05 mm Hg/year (95% CI 0.012 to 0.084, r2 = 0.05, p = 0.01). The intraobserver variability of GAT and DCT was 1.7 mm Hg and 3.2 mm Hg, respectively. The interobserver variability was (mean difference (95% limits of agreement)) 0.4 (-3.5 to 4.2) mm Hg for GAT and 0.2 (-4.9 to 5.3) mm Hg for DCT.

CONCLUSIONS

GAT is significantly more affected than DCT by both CCT and subject age. The effect of age suggests an age related corneal biomechanical change that may induce measurement error additional to that of CCT. The prototype DCT has greater measurement variability than the GAT.

Variable CD7 expression on T cells in the leukemic phase of cutaneous T cell lymphoma (Sézary syndrome)

CD7, a molecule normally expressed on 90% of normal CD4+ T cells, is often deficient on the malignant T cells of cutaneous T cell lymphoma. To investigate the clinical and biologic implications of CD7 expression, blood lymphocytes from 42 patients with the leukemic phase of cutaneous T cell lymphoma (CD4/CD8 ratio of 10 or more with evidence of a T cell clone in the blood) were analyzed for level of expression of CD7 by flow cytometry. CD7 expression by cells did not clearly segregate into two distinct subgroups that are either CD7 positive or CD7 negative as generally thought; however, nine of 17 patients with a predominantly CD4+CD7+ tumor population on early studies became CD4+CD7- over time whereas the converse situation was not observed. In addition, of three patients with evidence of large tumor cells in the blood coexisting with smaller cells, discordant CD7 expression was observed in one instance. In lymph node specimens, the percentage of cells expressing CD7 and other T cell markers did not correlate with histologic evidence of involvement. CD7 expression on blood lymphocytes also did not correlate with patients' survival nor to serum IgE levels or blood eosinophil counts, a finding suggesting that this marker does not identify functional cell subsets that produce serum interleukin-4 or -5, respectively. We speculate that the level of CD7 expression on malignant T cells may be the effect of sustained antigen stimulation in vivo analogous to what has been proposed to occur with normal T cells during aging.

Optic disc changes following trabeculectomy: longitudinal and localisation of change

AIMS

To determine whether there were any changes in the optic disc at 2 years after trabeculectomy. To determine the factors that most influenced change and whether change was localised to any region of the optic disc.

METHODS

95 patients undergoing routine trabeculectomy as part of the ongoing Moorfields/MRC 5-fluorouracil trial were recruited into the study. Eyes were imaged preoperatively (4 (SD 3) weeks) with the Heidelberg retina tomograph (HRT, Heidelberg Engineering), and at 3 months (SD 2 weeks), 1 year (SD 1 month), and 2 years (SD 1 month) after surgery. Parameters investigated for change were rim area, rim volume, and maximum cup depth. The predefined segment analysis available on the HRT analysis software was used to determine segmental change.

RESULTS

The images of 70 patients were analysed. Intraocular pressure reduced from 22.25 (SD 3.76) mm Hg, at the time of preoperative imaging to 15.27 (SD 4.96) mm Hg at 3 months, 14.38 (SD 3.89) mm Hg at 1 year, and 13.80 (SD 3.54) mm Hg at 2 years after trabeculectomy. An increase in rim area and rim volume was present at all time points after surgery, but was only found to be statistically significant at 2 years after surgery. Maximum depth of cup reduced by month 3 and month 12, but showed a slight increase at 2 years after surgery, although this was still lower than the preoperative measure. Segmental analysis found a significant change in rim volume in the nasal, inferonasal, superonasal, and superotemporal regions at 2 years after surgery. No significant regional localisation for change was found at any other time point or in any other parameter investigated.

CONCLUSIONS

Reversal of disc cupping is present at 2 years after trabeculectomy. The factor most influencing change is reduction of intraocular pressure. Segmental analysis showed that change in rim volume was greatest in the nasal, inferonasal, superonasal and superotemporal regions at 2 years.

Superficial keratectomy and conjunctival autograft for Fuchs' superficial marginal keratitis

PURPOSE

To describe a patient with bilateral, recurrent marginal corneal infiltrates consistent with Fuchs' superficial marginal keratitis who developed bilateral nasal pseudopterygia encroaching on the visual axis, reducing visual acuity in both eyes.

METHODS

Bilateral superficial keratectomy combined with conjunctival autografting was performed in each eye.

RESULTS

Best corrected visual acuity improved from 20/60 in the left eye and 20/40 in the right eye to 20/25 in both eyes. Our patient has had no disease relapses in her right eye, as of 29 months after the surgery, but experienced a mild flare-up of marginal keratitis in her left eye 8 months after the surgery. Despite this flare-up, disease symptoms in the left eye have markedly diminished.

CONCLUSION

Superficial keratectomy combined with conjunctival autograft is a therapeutic alternative in the management of severe, recurrent Fuchs' superficial marginal keratitis. In the present case, it has resulted in an improvement in visual acuity as well as a decrease in the frequency of disease flare-ups. The clinical course of this patient suggests that the conjunctiva may play a role in the etiology of Fuchs' superficial marginal keratitis.

Anterior chamber flare after trabeculectomy and after phacoemulsification

AIMS

To evaluate and compare prospectively the anterior chamber inflammatory response after phacoemulsification cataract surgery and after trabeculectomy with peripheral iridectomy.

METHODS

Anterior chamber inflammation was measured using the Kowa FM-500 laser flare meter in 131 patients undergoing trabeculectomy and 148 patients undergoing phacoemulsification cataract extraction with intraocular lens implantation. Flare was measured before surgery and on each postoperative visit up to 12 months.

RESULTS

Before surgery there was no significant difference in flare readings between the two groups. Following trabeculectomy flare returned to baseline levels 4 weeks after surgery, while following phacoemulsification cataract extraction it remained significantly higher at week 6 (p<0.006) and month 3 (p<0.05).

CONCLUSIONS

Anterior chamber inflammation is more prolonged after cataract surgery than after trabeculectomy. This may have implications for the timing of trabeculectomy in relation to cataract surgery.

Sponge delivery variables and tissue levels of 5-fluorouracil

AIM

To study how the delivery of 5-fluorouracil (5-FU) to ocular tissues is affected by altering delivery variables.

METHOD

Sponge(s) soaked in radiolabelled 5-FU were placed between the conjunctiva and sclera of pig eyes. Application time, sponge size, sponge make (Altomed, Weck, Merocel), and 5-FU concentration were varied. Conjunctival and scleral tissue levels were determined in samples taken from the application site.

RESULTS

Dose-response curves for scleral and conjunctival 5-FU levels against application time showed increasing tissue levels that reached a plateau after 2-3 minutes. Application beyond 3 minutes did not increase tissue levels. There was no difference in tissue levels between 7x4 and 3. 5x2 mm sponges. Altomed sponges produced 5-FU tissue levels that were twice as high as those obtained with Weck-cell (p<0.01) or Merocel (p<0.02) sponges. Changing the 5-FU concentration from 25 mg/ml to 6.25 mg/ml reduced the conjunctival concentration by a factor of 3.5 (p<0.003).

CONCLUSION

Application time up to 3 minutes, sponge make, and 5-FU concentration can have a large effect on the tissue delivery of 5-FU. Application time beyond 3 minutes, using 3.5x2 mm or 7x4 mm sponges, and replacing sponges every minute did not have a significant effect on tissue levels. This study models the effect that different variables can have on the ocular tissue levels of an antimetabolite applied intraoperatively.