Genetic Diagnosis of Retinoblastoma Using Aqueous Humour-Findings from an Extended Cohort

The identification of somatic RB1 variation is crucial to confirm the heritability of retinoblastoma. We and others have previously shown that, when tumour DNA is unavailable, cell-free DNA (cfDNA) derived from aqueous humour (AH) can be used to identify somatic RB1 pathogenic variation. Here we report RB1 pathogenic variant detection, as well as cfDNA concentration in an extended cohort of 75 AH samples from 68 patients. We show cfDNA concentration is highly variable and significantly correlated with the collection point of the AH. Cell-free DNA concentrations above 5 pg/µL enabled the detection of 93% of known or expected RB1 pathogenic variants. In AH samples collected during intravitreal chemotherapy treatment (Tx), the yield of cfDNA above 5 pg/µL and subsequent variant detection was low (≤46%). However, AH collected by an anterior chamber tap after one to three cycles of primary chemotherapy (Dx1+) enabled the detection of 75% of expected pathogenic variants. Further limiting our analysis to Dx1+ samples taken after ≤2 cycles (Dx ≤ 2) provided measurable levels of cfDNA in all cases, and a subsequent variant detection rate of 95%. Early AH sampling is therefore likely to be important in maximising cfDNA concentration and the subsequent detection of somatic RB1 pathogenic variants in retinoblastoma patients undergoing conservative treatment.

Retinal pigment epithelium exhibits gene expression and phagocytic activity alterations when exposed to retinoblastoma chemotherapeutics

Retinoblastoma (Rb) is a rare malignant disorder affecting the developing retina of children under the age of five. Chemotherapeutic agents used for treating Rb have been associated with defects of the retinal pigment epithelium (RPE), such as hyperplasia, gliosis, and mottling. Herein, we have developed two pluripotent stem cell (PSC)-RPE models to assess the cytotoxicity of known Rb chemotherapeutics such as Melphalan, Topotecan and TW-37. Our findings demonstrate that these drugs alter the RPE by decreasing the monolayer barrier's trans-epithelial resistance and affecting the cells' phagocytic activity. Transcriptional analyses demonstrate an altered expression of genes involved in melanin and retinol processing, tight junction and apical-basal polarity pathways in both models. When applied within the clinical range, none of the drug treatments caused significant cytotoxic effects, changes to the apical-basal polarity, tight junction network or cell cycle. Together, our results demonstrate that although the most commonly used Rb chemotherapeutic drugs do not cause cytotoxicity in RPE, their application in vitro leads to compromised phagocytosis and strength of the barrier function, in addition to changes in gene expression that could alter the visual cycle in vivo. Our data demonstrate that widely used Rb chemotherapeutic drugs can have a deleterious impact on RPE cells and thus great care has to be exercised with regard to their delivery so the adjacent healthy RPE is not damaged during the course of tumor eradication.

Outcomes following tacrolimus systemic immunosuppression for penetrating keratoplasty in infants and young children

OBJECTIVE

To report outcomes of tacrolimus immunosuppression after penetrating keratoplasty (PK) in very young children.

METHODS

Retrospective, consecutive, cohort study of children undergoing PK at a tertiary children's hospital between 2005 and 2016. Oral tacrolimus immunosuppression was given for 2 years, followed by topical tacrolimus.

RESULTS

Fourteen children (20 eyes) had 24 PKs; nineteen eyes had primary PKs, five eyes had repeat PKs. Mean age at primary graft was 95 days (3.1 months) for anterior segment dysgenesis (ASD), 430 days (14.3 months) for non-ASD children. Eleven children (15 eyes) had ASD. Three children (five eyes) had non-ASD: two children (three eyes) had glaucoma-related corneal opacity and one child (two eyes) had congenital hereditary endothelial dystrophy (CHED). One-year rejection-free survival rates following primary PK was 80% for ASD (n = 15) and 100% for non-ASD (n = 4). At final review, 5/15 of primary grafts for ASD were clear. 10/15 failed after a mean of 19 months, specifically attributable to infection (n = 2), rejection (n = 2) and glaucoma (n = 2). 4/4 primary non-ASD grafts are clear at final review (mean follow-up = 77 months). All repeat grafts (n = 5), failed after a mean of 38.25 months. Considering all grafts, 15/24 (62.5%) failed: 5/15 due to infection, 2/15 due to rejection, 8/15 due to glaucoma, phthisis, perforation or vascularised with no rejection. At last review (mean = 58.1 months, range 28-84), overall cohort survival is 37.5%. Final visual acuities range between 0.86 and 2.4 LogMAR.

CONCLUSION

We compare our results to published literature: 1-year graft survival was higher than previously reported, with lower failure due to rejection. Overall infection rates did not increase, however, proportionally, severe infections were higher. Overall graft survival is at least comparable to reported literature.

Emerging New Therapeutics for Retinoblastoma

Background: Over the last few decades, chemotherapy has become the main treatment of retinoblastoma, delivered through various routes: intravenous, intra-arterial, and intravitreal. Despite its efficacy, chemotherapy-related toxicity (ocular and systemic) and recurrences due to resistant tumor clones are common, highlighting the need for novel therapeutic agents. Summary: Recent advances in our understanding of the molecular drivers of Rb1 tumorigenesis and mechanisms of tumor resistance have afforded opportunities to explore novel targets such as the MDMX-p53 pathway (nutlin-3), histone deacetylase inhibitors, spleen tyrosine kinase inhibitors, and genetic and immune modulatory drugs. In this review, we discuss the limitations of current therapeutic strategies, candidate cellular pathways, current evidence for newer targeted drugs, and offer a look toward the future. Key Messages: Advances in the understanding of the molecular drivers of the RB pathway have provided opportunities to explore novel drugs with targeted effects, improved bioavailability, and reduced chemotoxicity.

pRB-Depleted Pluripotent Stem Cell Retinal Organoids Recapitulate Cell State Transitions of Retinoblastoma Development and Suggest an Important Role for pRB in Retinal Cell Differentiation

Retinoblastoma (Rb) is a childhood cancer of the developing retina, accounting for up to 17% of all tumors in infancy. To gain insights into the transcriptional events of cell state transitions during Rb development, we established 2 disease models via retinal organoid differentiation of a pRB (retinoblastoma protein)-depleted human embryonic stem cell line (RB1-null hESCs) and a pRB patient-specific induced pluripotent (iPSC) line harboring a RB1 biallelic mutation (c.2082delC). Both models were characterized by pRB depletion and accumulation of retinal progenitor cells at the expense of amacrine, horizontal and retinal ganglion cells, which suggests an important role for pRB in differentiation of these cell lineages. Importantly, a significant increase in the fraction of proliferating cone precursors (RXRγ+Ki67+) was observed in both pRB-depleted organoid models, which were defined as Rb-like clusters by single-cell RNA-Seq analysis. The pRB-depleted retinal organoids displayed similar features to Rb tumors, including mitochondrial cristae aberrations and rosette-like structures, and were able to undergo cell growth in an anchorage-independent manner, indicative of cell transformation in vitro. In both models, the Rb cones expressed retinal ganglion and horizontal cell markers, a novel finding, which could help to better characterize these tumors with possible therapeutic implications. Application of Melphalan, Topotecan, and TW-37 led to a significant reduction in the fraction of Rb proliferating cone precursors, validating the suitability of these in vitro models for testing novel therapeutics for Rb.

Defining High-Risk Retinoblastoma: A Multicenter Global Survey

Importance

High-risk histopathologic features of retinoblastoma are useful to assess the risk of systemic metastasis. In this era of globe salvage treatments for retinoblastoma, the definition of high-risk retinoblastoma is evolving.

Objective

To evaluate variations in the definition of high-risk histopathologic features for metastasis of retinoblastoma in different ocular oncology practices around the world.

Design, Setting, and Participants

An electronic web-based, nonvalidated 10-question survey was sent in December 2020 to 52 oncologists and pathologists treating retinoblastoma at referral retinoblastoma centers.

Intervention

Anonymized survey about the definition of high-risk histopathologic features for metastasis of retinoblastoma.

Main Outcomes and Measures

High-risk histopathologic features that determine further treatment with adjuvant systemic chemotherapy to prevent metastasis.

Results

Among the 52 survey recipients, the results are based on the responses from 27 individuals (52%) from 24 different retinoblastoma practices across 16 countries in 6 continents. The following were considered to be high-risk features: postlaminar optic nerve infiltration (27 [100%]), involvement of optic nerve transection (27 [100%]), extrascleral tissue infiltration (27 [100%]), massive (≥3 mm) choroidal invasion (25 [93%]), microscopic scleral infiltration (23 [85%]), ciliary body infiltration (20 [74%]), trabecular meshwork invasion (18 [67%]), iris infiltration (17 [63%]), anterior chamber seeds (14 [52%]), laminar optic nerve infiltration (13 [48%]), combination of prelaminar and laminar optic nerve infiltration and minor choroidal invasion (11 [41%]), minor (<3 mm) choroidal invasion (5 [19%]), and prelaminar optic nerve infiltration (2 [7%]). The other histopathologic features considered high risk included Schlemm canal invasion (4 [15%]) and severe anaplasia (1 [4%]). Four respondents (15%) said that the presence of more than 1 high-risk feature, especially a combination of massive peripapillary choroidal invasion and postlaminar optic nerve infiltration, should be considered very high risk for metastasis.

Conclusions and Relevance

Responses to this nonvalidated survey conducted in 2020-2021 showed little uniformity in the definition of high-risk retinoblastoma. Postlaminar optic nerve infiltration, involvement of optic nerve transection, and extrascleral tumor extension were the only features uniformly considered as high risk for metastasis across all oncology practices. These findings suggest that the relevance about their value in the current scenario with advanced disease being treated conservatively needs further evaluation; there is also a need to arrive at consensus definitions and conduct prospective multicenter studies to understand their relevance.

Dissecting the Transcriptional and Chromatin Accessibility Heterogeneity of Proliferating Cone Precursors in Human Retinoblastoma Tumors by Single Cell Sequencing-Opening Pathways to New Therapeutic Strategies?

Purpose

Retinoblastoma (Rb) is a malignant neoplasm arising during retinal development from mutations in the RB1 gene. Loss or inactivation of both copies of RB1 results in initiation of retinoblastoma tumors; however, additional genetic changes are needed for the continued growth and spread of the tumor. Ex vivo research has shown that in humans, retinoblastoma may initiate from RB1-depleted cone precursors. Notwithstanding, it has not been possible to assess the full spectrum of clonal types within the tumor itself in vivo and the molecular changes occurring at the cells of origin, enabling their malignant conversion. To overcome these challenges, we have performed the first single cell (sc) RNA- and ATAC-Seq analyses of primary tumor tissues, enabling us to dissect the transcriptional and chromatin accessibility heterogeneity of proliferating cone precursors in human Rb tumors.

Methods

Two Rb tumors each characterized by two pathogenic RB1 mutations were dissociated to single cells and subjected to scRNA-Seq and scATAC-Seq using the 10× Genomics platform. In addition, nine human embryonic and fetal retina samples were dissociated to single cells and subjected to scRNA- and ATAC-Seq analyses. The scRNA- and ATAC-Seq data were embedded using Uniform Manifold Approximation and Projection and clustered with Seurat graph-based clustering. Integrated scATAC-Seq analysis of Rb tumors and human embryonic/fetal retina samples was performed to identify Rb cone enriched subclusters. Pseudo time analysis of proliferating cones in the Rb samples was performed with Monocle. Ingenuity Pathway Analysis was used to identify the signaling pathway and upstream regulators in the Rb cone-enriched subclusters.

Results

Our single cell analyses revealed the predominant presence of cone precursors at different stages of the cell cycle in the Rb tumors and among those identified the G2/M subset as the cell type of origin. scATAC-Seq analysis identified two Rb enriched cone subclusters, each characterized by activation of different upstream regulators and signaling pathways, enabling proliferating cone precursors to escape cell cycle arrest and/or apoptosis.

Conclusions

Our study provides evidence of Rb tumor heterogeneity and defines molecular pathways that can be targeted to define new treatment strategies.

Adjuvant use of laser in eyes with macular retinoblastoma treated with primary intravenous chemotherapy

BACKGROUND

Adjuvant use of laser with systemic chemotherapy for treatment of retinoblastoma may reduce recurrence rates while also causing local side effects. Information is lacking on the effect of laser on visual outcomes.

METHODS

A retrospective review of two retinoblastoma centres in the United Kingdom was conducted. Patients were included if there was a macular tumour in at least one eye. Eyes that received chemotherapy alone were compared with eyes that received chemotherapy plus adjuvant laser.

RESULTS

A total of 76 patients and 91 eyes were included in the study. Systemic chemotherapy alone was used in 71 eyes while chemotherapy plus laser was used in 20 eyes. Demographic characteristics of both groups were similar. Macular relapse rates were similar between groups: 22/71 (31%) eyes in chemotherapy group and 9/20 (45%) eyes in laser group (p=0.29). There was no increase in vitreous relapses in the laser group (2/20 eyes), compared with the chemotherapy group 10/71 eyes (p=0.99). Survival analysis demonstrated similar time to first relapse between groups. Final visual acuity was equal between groups with 6/15 or better present in 31.1% of eyes in the chemotherapy group and 37.5% of eyes in the laser group (p=0.76). Presence of tumour at the fovea was predictive of final visual acuity, regardless of treatment group.

CONCLUSION

Adjuvant laser in the treatment of retinoblastoma is safe and does not lead to increased rate of vitreous recurrence. Final visual acuity is determined by the presence of tumour at the fovea and not the use of laser.

Travel burden and clinical presentation of retinoblastoma: analysis of 1024 patients from 43 African countries and 518 patients from 40 European countries

BACKGROUND

The travel distance from home to a treatment centre, which may impact the stage at diagnosis, has not been investigated for retinoblastoma, the most common childhood eye cancer. We aimed to investigate the travel burden and its impact on clinical presentation in a large sample of patients with retinoblastoma from Africa and Europe.

METHODS

A cross-sectional analysis including 518 treatment-naïve patients with retinoblastoma residing in 40 European countries and 1024 treatment-naïve patients with retinoblastoma residing in 43 African countries.

RESULTS

Capture rate was 42.2% of expected patients from Africa and 108.8% from Europe. African patients were older (95% CI -12.4 to -5.4, p<0.001), had fewer cases of familial retinoblastoma (95% CI 2.0 to 5.3, p<0.001) and presented with more advanced disease (95% CI 6.0 to 9.8, p<0.001); 43.4% and 15.4% of Africans had extraocular retinoblastoma and distant metastasis at the time of diagnosis, respectively, compared to 2.9% and 1.0% of the Europeans. To reach a retinoblastoma centre, European patients travelled 421.8 km compared to Africans who travelled 185.7 km (p<0.001). On regression analysis, lower-national income level, African residence and older age (p<0.001), but not travel distance (p=0.19), were risk factors for advanced disease.

CONCLUSIONS

Fewer than half the expected number of patients with retinoblastoma presented to African referral centres in 2017, suggesting poor awareness or other barriers to access. Despite the relatively shorter distance travelled by African patients, they presented with later-stage disease. Health education about retinoblastoma is needed for carers and health workers in Africa in order to increase capture rate and promote early referral.

Role of ethnicity and socioeconomic status (SES) in the presentation of retinoblastoma: findings from the UK

Background

The relationship between the ethnic background or socioeconomic status (SES) and late retinoblastoma (Rb) presentation in the UK is unclear. We aimed to investigate if such correlations exist in a cohort of non-familial Rb cases.

Methods

A cross-sectional study based at the two centres providing Rb care in the UK. Included were non-familial Rb cases that presented from January 2006 to December 2011. Epidemiological and clinical data were retrieved from medical charts, as well as patients’ postcodes used to obtain the Index of Multiple Deprivation (IMD) score. A postal questionnaire was sent to participants’ parents to collect further, person-level, information on languages spoken and household socioeconomic position. Statistical correlations to advanced Rb at presentation as well as to treatment by enucleation and need for adjuvant chemotherapy were investigated.

Results

The cohort included 189 cases, 98 (51.8%) of which were males. The median age at diagnosis was 16 months (IQR 8–34 months). Of the study patients, 153 (81%) presented with advanced Rb; 78 (41%) with group D and 75 (40%) with group E Rb. A total of 134 (72%) patients were treated with enucleation. South Asian ethnicity and being in the most deprived IMD quintile were associated with a higher likelihood of presentation with advanced disease, but these estimates did not reach statistical significance. Older age at presentation was associated with enucleation and bilateral disease with adjuvant chemotherapy.

Conclusions

In this national UK study of patients with non-familial Rb, there was no evidence of an association of ethnicity or SES and the risk of presenting with advanced disease. These findings may reflect equality in access of healthcare in the UK.

Global Retinoblastoma Presentation and Analysis by National Income Level

Importance

Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale.

Objectives

To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis.

Design, Setting, and Participants

A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017.

Main Outcomes and Measures

Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis.

Results

The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4%) were female. Most patients (n = 3685 [84.7%]) were from low- and middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 [62.8%]), followed by strabismus (n = 429 [10.2%]) and proptosis (n = 309 [7.4%]). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 [95% CI, 12.94-24.80], and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 [95% CI, 4.30-7.68]).

Conclusions and Relevance

This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs.

Non-invasive diagnosis of retinoblastoma using cell-free DNA from aqueous humour

Retinoblastoma is the most common eye malignancy in childhood caused by mutations in the RB1 gene. Both alleles of the RB1 gene must be mutated for tumour development. The initial RB1 mutation may be constitutional germline or somatic (originating in one retinal cell only). Distinguishing between these alternative mechanisms is crucial, with wider implications for management of the patient and family members. Bilateral retinoblastoma is nearly always due to a constitutional mutation; however, approximately 15% of unilateral cases also carry a germline mutation, and identifying these cases is important. This can be achieved by identifying both mutation types in tumour tissue and excluding their presence in blood. Modern eye-saving chemotherapy treatment (systemic, intra-arterial and intravitreal) has resulted in fewer enucleations. As a result, tumour tissue required to identify sporadic RB1 mutation(s) is not always available. Modern intravitreal chemotherapeutic techniques for retinoblastoma involve aspiration of aqueous humour (AH), providing a novel sample source for analysis. By analysing cell-free DNA present in the AH fluid of eyes affected with retinoblastoma, we have developed a screening test capable of detecting somatic RB1 mutations that is comparable to current tests on enucleated tumour tissue. The results obtained with fluid from enucleated eyes were concordant with tumour tissue in all 10 cases analysed. In addition, AH analysis from two patients undergoing intravitreal chemotherapy successfully identified somatic variants in both cases. Our findings suggest that AH fluid is a promising source of tumour-derived DNA in retinoblastoma for analysis.

How to use…the direct ophthalmoscope

Ophthalmoscopy and red reflex examination are core medical skills required to identify sight-threatening and life-threatening disease. We discuss the predictive utility and limitations of findings with an ophthalmoscope and tips as to how to optimise these. We outline important considerations in three clinical scenarios: an abnormal red reflex, an abnormal optic disc and retinal haemorrhages in the context of child protection concerns.

Patient understanding of genetic information influences reproductive decision making in retinoblastoma

BACKGROUND

Retinoblastoma is the most common malignant tumour of the eye in childhood, with nearly all bilateral tumours and around 17% to 18% of unilateral tumours due to an oncogenic mutation in the RB1 gene in the germline. Genetic testing enables accurate risk assessment and optimal clinical management for the affected individual, siblings, and future offspring.

MATERIAL AND METHODS

We carried out the first UK-wide audit of understanding of genetic testing in individuals with retinoblastoma. A total of 292 individuals aged 16 to 45 years were included.

RESULTS

Patients with bilateral disease were significantly more likely to understand the implications of retinoblastoma for siblings and children. There was a significant association between not knowing the results of genetic testing or not understanding the implications and not having children, particularly in women. Surprisingly, this was also true for individuals treated for unilateral disease with a low risk of retinoblastoma for their offspring.

CONCLUSION

We are concerned that individuals may be making life choices based on insufficient information regarding risks of retinoblastoma and reproductive options. We suggest that improvement in transition care is needed to enable individuals to make informed reproductive decisions and to ensure optimal care for children born at risk of retinoblastoma.

Metabolite profiling in retinoblastoma identifies novel clinicopathological subgroups

BACKGROUND

Tumour classification, based on histopathology or molecular pathology, is of value to predict tumour behaviour and to select appropriate treatment. In retinoblastoma, pathology information is not available at diagnosis and only exists for enucleated tumours. Alternative methods of tumour classification, using noninvasive techniques such as magnetic resonance spectroscopy, are urgently required to guide treatment decisions at the time of diagnosis.

METHODS

High-resolution magic-angle spinning magnetic resonance spectroscopy (HR-MAS MRS) was undertaken on enucleated retinoblastomas. Principal component analysis and cluster analysis of the HR-MAS MRS data was used to identify tumour subgroups. Individual metabolite concentrations were determined and were correlated with histopathological risk factors for each group.

RESULTS

Multivariate analysis identified three metabolic subgroups of retinoblastoma, with the most discriminatory metabolites being taurine, hypotaurine, total-choline and creatine. Metabolite concentrations correlated with specific histopathological features: taurine was correlated with differentiation, total-choline and phosphocholine with retrolaminar optic nerve invasion, and total lipids with necrosis.

CONCLUSIONS

We have demonstrated that a metabolite-based classification of retinoblastoma can be obtained using ex vivo magnetic resonance spectroscopy, and that the subgroups identified correlate with histopathological features. This result justifies future studies to validate the clinical relevance of these subgroups and highlights the potential of in vivo MRS as a noninvasive diagnostic tool for retinoblastoma patient stratification.

Gene expression profiling identifies different sub-types of retinoblastoma

Background:

Mutation of the RB1 gene is necessary but not sufficient for the development of retinoblastoma. The nature of events occurring subsequent to RB1 mutation is unclear, as is the retinal cell-of-origin of this tumour.

Methods:

Gene expression profiling of 21 retinoblastomas was carried out to identify genetic events that contribute to tumorigenesis and to obtain information about tumour histogenesis.

Results:

Expression analysis showed a clear separation of retinoblastomas into two groups. Group 1 retinoblastomas express genes associated with a range of different retinal cell types, suggesting derivation from a retinal progenitor cell type. Recurrent chromosomal alterations typical of retinoblastoma, for example, chromosome 1q and 6p gain and 16q loss were also a feature of this group, and clinically they were characterised by an invasive pattern of tumour growth. In contrast, group 2 retinoblastomas were found to retain many characteristics of cone photoreceptor cells and appear to exploit the high metabolic capacity of this cell type in order to promote tumour proliferation.

Conclusion:

Retinoblastoma is a heterogeneous tumour with variable biology and clinical characteristics.

Septo-optic dysplasia: antenatal risk factors and clinical features in a regional study

BACKGROUND

Septo-optic dysplasia (SOD) is a disorder with postulated environmental and genetic aetiology. This study delineates clinical features and potential perinatal environmental factors along with epidemiology in SOD children.

METHODS

Assessment of patients with SOD triad features in the UK West Midlands region.

RESULTS

Of 227 patients identified between 1998 and 2009 with 1 or more feature of the triad, 55 had midline defects, 149 had optic nerve hypoplasia and 132 had hypopituitarism. Eighty-eight children (52% males; incidence 8.3/100,000 live births) had SOD defined as 2 out of 3 features and 21 (24%) had all 3. Sixty-one percent had anterior pituitary deficiency and 21.5% had diabetes insipidus. Median maternal/paternal ages in SOD were 21 and 23.5 years, compared to UK means of 29.3 and 32.4 years (p < 0.001). First trimester bleeding was markedly increased at 12/48 (25%) compared to 0.07% in the UK (p < 0.001). Ethnicity showed a non-significant higher prevalence in Afro-Caribbean and mixed race groups, and significantly lower prevalence (p = 0.004) in South Asian groups compared to West Midland and Birmingham city data: 8% versus 2.5 and 6.7%, 9% versus 1.8 and 3.2% and 3% versus 8.4 and 21%, respectively.

CONCLUSIONS

SOD is associated with younger maternal and paternal age, primigravida births and ethnic differences. Increased first trimester bleeding may indicate that SOD is a vascular disruption sequence.

Feasibility of day-case vitreoretinal surgery

PURPOSE

The indications for vitreoretinal (VR) surgery are increasing as equipment and techniques available improve. In order to decrease demand on limited health resources, day-case surgery would be beneficial in many cases. This study combines a retrospective and prospective arm to examine the feasibility and safety of routine day-case VR surgery.

METHODS

One hundred consecutive patients (50 retrospective and 50 prospective) undergoing VR surgery within the Royal Berkshire NHS trust were included. The retrospective arm aimed to identify the frequency and type of acute ophthalmic or medical intervention during postop overnight stay and the results were used to alter management in the prospective group. The prospective group consisted of patients undergoing a mixture of overnight stay and day-case surgery. All patients in the prospective group had routine subtenon marcaine anaesthesia together with prophylactic pre-operative intravenous acetazolamide. Patients deemed fit postoperatively were offered overnight ward discharge, with obligatory next-day review.

RESULTS

In the retrospective arm, 56% required oral nonsteroidal analgesia on the day of surgery and one patient required narcotic analgesia. Twenty-two per cent patients required intraocular pressure (IOP) control on the day of surgery and one patient required medical intervention in the form of urinary catheterisation. Nineteen patients required intervention on next-day review. In the prospective arm, 86% preferred day case and were suitable, 6% were suitable for day-case but preferred overnight stay and 8% were deemed not fit for discharge. No patient required narcotic analgesics. No patient discharged returned as a casualty overnight. Only one patient required topical beta-blocker for the control of IOP on next-day review.

CONCLUSIONS

These data suggest that many patients who are hospitalised overnight for VR surgery could be safely treated as day cases. Such a shift in the pattern of care for VR surgery could provide a significant improvement in health-care efficiency and minimise patient inconvenience.

Spontaneous foreign body extrusion following perforating eye injury

A structured approach to the management of a perforating ballistic eye injury is illustrated in this case, where initial treatment was limited to simple corneal wound closure and antibiotic prophylaxis. A pellet had passed completely through the globe but the retina remained attached, and it was decided to manage the case conservatively. Two retained foreign bodies were extruded spontaneously some months after the injury when suture removal and delayed cataract surgery led to a virtually perfect visual outcome. The patient has had no further complications at least three years after initial injury. The management of this civilian case illustrates some basic concepts in treating ballistic eye injuries that may be applicable in a military setting.

Abnormal pupillary activity in a brainstem-dead patient

The pupils in brainstem-dead patients are classically fixed and dilated. We present a case of a brainstem-dead patient whose pupils displayed persistent asynchronous pupillary constriction and dilatation independent of external physical stimuli. Central causes for the phenomenon were excluded leaving an unexplained peripheral cause as the most likely explanation. Early recognition of this phenomenon prevents delay in the diagnosis of brainstem death, lessening to some extent the distress for the family, and facilitating earlier organ donation and allowing the better use of resources.

Detection of low molecular mass GTP-binding proteins in chromaffin granules and other subcellular fractions of chromaffin cells

A homogenate of purified chromaffin cells was fractionated, after removal of the nuclear fraction, by sucrose density gradient ultracentrifugation. The presence and subcellular localization of low molecular mass GTP-binding proteins was explored by incubation of blots of proteins from different subcellular fractions with [alpha-32P]GTP in the presence of Mg2+. The fractions enriched in intact chromaffin granule markers, i.e. catecholamines, chromogranin A, chromogranin B and cytochrome b-561 were also enriched in labelled GTP-binding proteins. Two major labelled components of 23 and 29 kDa were rapidly detected by autoradiography. Traces of 26 and 27 kDa components were also present. These components were detectable in both plasma and granule membranes. In addition to these components, the cytosolic fraction contained another GTP-binding protein of about 20 kDa. Binding of [alpha-32P]GTP was specific and dependent on Mg2+. By analogy to the findings reported in non-mammalian systems, the observations described here suggest the involvement of low molecular mass GTP-binding proteins in the chromaffin cell secretory process.

A teratological evaluation and analysis of fetal tissue levels following administration of tetrachlorobenzene isomers to the rat

Three tetrachlorobenzene (TCB) congeners (1,2,3,4- 1,2,3,5-, and 1,2,4,5-) were administered daily by gavage to pregnant Sprague-Dawley rats at levels of 50, 100, or 200 mg/kg from day 6 through day 15 of gestation. Mothers were sacrificed on day 21 of gestation and the pups removed by cesarian section for teratological evaluation. Administration of 1,2,3,4- and 1,2,3,5-TCB failed to alter maternal body weight, organ weights, hematological, or the biochemical parameters studied. The highest dose level of 1,2,4,5-tetrachlorobenzene caused maternal death in nine of ten animals. In addition it induced mixed function oxidases and increased serum cholesterol values at 50 and 100 mg/kg. There was a decrease in the number of fetuses at the highest dose levels of 1,2,3,4- and 1,2,3,5-TCB and at the lowest dose level of the 1,2,4,5- congener. None of the congeners produced any anomalies. There were no treatment-related histopathological changes in either the mothers or fetuses. Residues of all three congeners were found in maternal and fetal tissues but generally the amounts of the 1,2,4,5- isomer were about 100 times higher than the other two.