Incorporating environmental heterogeneity and observation effort to predict host distribution and viral spillover from a bat reservoir

Predicting the spatial occurrence of wildlife is a major challenge for ecology and management. In Latin America, limited knowledge of the number and locations of vampire bat roosts precludes informed allocation of measures intended to prevent rabies spillover to humans and livestock. We inferred the spatial distribution of vampire bat roosts while accounting for observation effort and environmental effects by fitting a log Gaussian Cox process model to the locations of 563 roosts in three regions of Peru. Our model explained 45% of the variance in the observed roost distribution and identified environmental drivers of roost establishment. When correcting for uneven observation effort, our model estimated a total of 2340 roosts, indicating that undetected roosts (76%) exceed known roosts (24%) by threefold. Predicted hotspots of undetected roosts in rabies-free areas revealed high-risk areas for future viral incursions. Using the predicted roost distribution to inform a spatial model of rabies spillover to livestock identified areas with disproportionate underreporting and indicated a higher rabies burden than previously recognized. We provide a transferrable approach to infer the distribution of a mostly unobserved bat reservoir that can inform strategies to prevent the re-emergence of an important zoonosis.

SumStatsRehab: an efficient algorithm for GWAS summary statistics assessment and restoration

Background

Generating polygenic risk scores for diseases and complex traits requires high quality GWAS summary statistic files. Often, these files can be difficult to acquire either as a result of unshared or incomplete data. To date, bioinformatics tools which focus on restoring missing columns containing identification and association data are limited, which has the potential to increase the number of usable GWAS summary statistics files.

Results

SumStatsRehab was able to restore rsID, effect/other alleles, chromosome, base pair position, effect allele frequencies, beta, standard error, and p-values to a better extent than any other currently available tool, with minimal loss.

Conclusions

SumStatsRehab offers a unique tool utilizing both functional programming and pipeline-like architecture, allowing users to generate accurate data restorations for incomplete summary statistics files. This in turn, increases the number of usable GWAS summary statistics files, which may be invaluable for less researched health traits.

Ecological determinants of rabies virus dynamics in vampire bats and spillover to livestock

The pathogen transmission dynamics in bat reservoirs underpin efforts to reduce risks to human health and enhance bat conservation, but are notoriously challenging to resolve. For vampire bat rabies, the geographical scale of enzootic cycles, whether environmental factors modulate baseline risk, and how within-host processes affect population-level dynamics remain unresolved. We studied patterns of rabies exposure using an 11-year, spatially replicated sero-survey of 3709 Peruvian vampire bats and co-occurring outbreaks in livestock. Seroprevalence was correlated among nearby sites but fluctuated asynchronously at larger distances. A generalized additive mixed model confirmed spatially compartmentalized transmission cycles, but no effects of bat demography or environmental context on seroprevalence. Among 427 recaptured bats, we observed long-term survival following rabies exposure and antibody waning, supporting hypotheses that immunological mechanisms influence viral maintenance. Finally, seroprevalence in bats was only weakly correlated with outbreaks in livestock, reinforcing the challenge of spillover prediction even with extensive data. Together our results suggest that rabies maintenance requires transmission among multiple, nearby bat colonies which may be facilitated by waning of protective immunity. However, the likelihood of incursions and dynamics of transmission within bat colonies appear largely independent of bat ecology. The implications of these results for spillover anticipation and controlling transmission at the source are discussed.

Longitudinal deep sequencing informs vector selection and future deployment strategies for transmissible vaccines

Vaccination is a powerful tool in combating infectious diseases of humans and companion animals. In most wildlife, including reservoirs of emerging human diseases, achieving sufficient vaccine coverage to mitigate disease burdens remains logistically unattainable. Virally vectored "transmissible" vaccines that deliberately spread among hosts are a potentially transformative, but still theoretical, solution to the challenge of immunising inaccessible wildlife. Progress towards real-world application is frustrated by the absence of frameworks to guide vector selection and vaccine deployment prior to major in vitro and in vivo investments in vaccine engineering and testing. Here, we performed deep sequencing on field-collected samples of Desmodus rotundus betaherpesvirus (DrBHV), a candidate vector for a transmissible vaccine targeting vampire bat-transmitted rabies. We discovered 11 strains of DrBHV that varied in prevalence and geographic distribution across Peru. The phylogeographic structure of DrBHV strains was predictable from both host genetics and landscape topology, informing long-term DrBHV-vectored vaccine deployment strategies and identifying geographic areas for field trials where vaccine spread would be naturally contained. Multistrain infections were observed in 79% of infected bats. Resampling of marked individuals over 4 years showed within-host persistence kinetics characteristic of latency and reactivation, properties that might boost individual immunity and lead to sporadic vaccine transmission over the lifetime of the host. Further, strain acquisitions by already infected individuals implied that preexisting immunity and strain competition are unlikely to inhibit vaccine spread. Our results support the development of a transmissible vaccine targeting a major source of human and animal rabies in Latin America and show how genomics can enlighten vector selection and deployment strategies for transmissible vaccines.

Selective Fusion in Lenke 1 B/C: Before or After Menarche?

STUDY DESIGN

A retrospective, comparative study.

OBJECTIVE

To determine the radiological behavior of the lumbar curve in selective fusions in premenarchal girls with adolescent idiopathic scoliosis (Lenke 1 B/C).

METHODS

A retrospective, comparative study was conducted. Selective fusion was performed in 21 patients younger than 18 years. The patients were divided into 2 groups: group A, after menarche (n = 12) and group B, before menarche (n = 9). Angles (preoperative, and at 1 and 2 years postoperatively) of the fused thoracic curves and the corresponding lumbar curves were measured and compared. For statistical analysis, the t test was used with a significance level of P < .05.

RESULTS

Mean preoperative angle value of the proximal/main thoracic curve was 61° in group A and 57° in group B (P = .44), and 21° and 20°, respectively, in the first year postoperatively (P = .61). Mean preoperative angle value of the lumbar curve was 43° in group A and 42° in group B (P = .87), while at 1 year after surgery, this curve was 19° in both groups (P = 0.91), and at 2 years postoperatively, the curve was 16° in group A and 17° in group B (P = .75).

CONCLUSIONS

Over a 2-year follow-up, we did not find significant radiological differences in lumbar curves between patients who underwent surgery before and after menarche.

Characterizing and Evaluating the Zoonotic Potential of Novel Viruses Discovered in Vampire Bats

The contemporary surge in metagenomic sequencing has transformed knowledge of viral diversity in wildlife. However, evaluating which newly discovered viruses pose sufficient risk of infecting humans to merit detailed laboratory characterization and surveillance remains largely speculative. Machine learning algorithms have been developed to address this imbalance by ranking the relative likelihood of human infection based on viral genome sequences, but are not yet routinely applied to viruses at the time of their discovery. Here, we characterized viral genomes detected through metagenomic sequencing of feces and saliva from common vampire bats (Desmodus rotundus) and used these data as a case study in evaluating zoonotic potential using molecular sequencing data. Of 58 detected viral families, including 17 which infect mammals, the only known zoonosis detected was rabies virus; however, additional genomes were detected from the families Hepeviridae, Coronaviridae, Reoviridae, Astroviridae and Picornaviridae, all of which contain human-infecting species. In phylogenetic analyses, novel vampire bat viruses most frequently grouped with other bat viruses that are not currently known to infect humans. In agreement, machine learning models built from only phylogenetic information ranked all novel viruses similarly, yielding little insight into zoonotic potential. In contrast, genome composition-based machine learning models estimated different levels of zoonotic potential, even for closely related viruses, categorizing one out of four detected hepeviruses and two out of three picornaviruses as having high priority for further research. We highlight the value of evaluating zoonotic potential beyond ad hoc consideration of phylogeny and provide surveillance recommendations for novel viruses in a wildlife host which has frequent contact with humans and domestic animals.

Detection of Trypanosoma cruzi in the saliva of diverse neotropical bats

Trypanosoma cruzi is widely reported in bats, yet transmission routes remain unclear. We present evidence from metagenomic sequence data that T. cruzi occurs in the saliva of diverse Neotropical bats. Phylogenetic analyses demonstrated that the bat-associated T. cruzi sequences described here formed part of a bat-specific clade, suggesting an independent transmission cycle. Our results highlight the value in repurposing metagenomic data generated for viral discovery to reveal insights into the biology of other parasites. Evaluating whether the presence of T. cruzi in the saliva of two hematophagous bat species represents an ecological route for zoonotic transmission of Chagas disease is an interesting avenue for future research.

Diversification of mammalian deltaviruses by host shifting

Hepatitis delta virus (HDV) is an unusual RNA agent that replicates using host machinery but exploits hepatitis B virus (HBV) to mobilize its spread within and between hosts. In doing so, HDV enhances the virulence of HBV. How this seemingly improbable hyperparasitic lifestyle emerged is unknown, but it underpins the likelihood that HDV and related deltaviruses may alter other host-virus interactions. Here, we show that deltaviruses diversify by transmitting between mammalian species. Among 96,695 RNA sequence datasets, deltaviruses infected bats, rodents, and an artiodactyl from the Americas but were absent from geographically overrepresented Old World representatives of each mammalian order, suggesting a relatively recent diversification within the Americas. Consistent with diversification by host shifting, both bat and rodent-infecting deltaviruses were paraphyletic, and coevolutionary modeling rejected cospeciation with mammalian hosts. In addition, a 2-y field study showed common vampire bats in Peru were infected by two divergent deltaviruses, indicating multiple introductions to a single host species. One vampire bat-associated deltavirus was detected in the saliva of up to 35% of individuals, formed phylogeographically compartmentalized clades, and infected a sympatric bat, illustrating horizontal transmission within and between species on ecological timescales. Consistent absence of HBV-like viruses in two deltavirus-infected bat species indicated acquisitions of novel viral associations during the divergence of bat and human-infecting deltaviruses. Our analyses support an American zoonotic origin of HDV and reveal prospects for future cross-species emergence of deltaviruses. Given their peculiar life history, deltavirus host shifts will have different constraints and disease outcomes compared to ordinary animal pathogens.

Distinct Roles of N-Terminal Fatty Acid Acylation of the Salinity-Sensor Protein SOS3

The Salt-Overly-Sensitive (SOS) pathway controls the net uptake of sodium by roots and the xylematic transfer to shoots in vascular plants. SOS3/CBL4 is a core component of the SOS pathway that senses calcium signaling of salinity stress to activate and recruit the protein kinase SOS2/CIPK24 to the plasma membrane to trigger sodium efflux by the Na/H exchanger SOS1/NHX7. However, despite the well-established function of SOS3 at the plasma membrane, SOS3 displays a nucleo-cytoplasmic distribution whose physiological meaning is not understood. Here, we show that the N-terminal part of SOS3 encodes structural information for dual acylation with myristic and palmitic fatty acids, each of which commands a different location and function of SOS3. N-myristoylation at glycine-2 is essential for plasma membrane association and recruiting SOS2 to activate SOS1, whereas S-acylation at cysteine-3 redirects SOS3 toward the nucleus. Moreover, a poly-lysine track in positions 7-11 that is unique to SOS3 among other Arabidopsis CBLs appears to be essential for the correct positioning of the SOS2-SOS3 complex at the plasma membrane for the activation of SOS1. The nuclear-localized SOS3 protein had limited bearing on the salt tolerance of Arabidopsis. These results are evidence of a novel S-acylation dependent nuclear trafficking mechanism that contrasts with alternative subcellular targeting of other CBLs by S-acylation.

Epidemiology and biology of a herpesvirus in rabies endemic vampire bat populations

Rabies is a viral zoonosis transmitted by vampire bats across Latin America. Substantial public health and agricultural burdens remain, despite decades of bats culls and livestock vaccinations. Virally vectored vaccines that spread autonomously through bat populations are a theoretically appealing solution to managing rabies in its reservoir host. We investigate the biological and epidemiological suitability of a vampire bat betaherpesvirus (DrBHV) to act as a vaccine vector. In 25 sites across Peru with serological and/or molecular evidence of rabies circulation, DrBHV infects 80-100% of bats, suggesting potential for high population-level vaccine coverage. Phylogenetic analysis reveals host specificity within neotropical bats, limiting risks to non-target species. Finally, deep sequencing illustrates DrBHV super-infections in individual bats, implying that DrBHV-vectored vaccines might invade despite the highly prevalent wild-type virus. These results indicate DrBHV as a promising candidate vector for a transmissible rabies vaccine, and provide a framework to discover and evaluate candidate viral vectors for vaccines against bat-borne zoonoses.

Patients with blunt traumatic thoracic aortic injury treated with TEVAR present increased flow dynamics alterations and pulse wave velocity: a 4D flow CMR study

Background

Thoracic endovascular aortic repair (TEVAR) is widely used for the treatment of blunt traumatic thoracic aortic injuries. Aortic flow dynamics and mechanical implications of this intervention are poorly investigated and may be of particular interest in the long-term follow-up of these mostly young patients.

Purpose

To assess whether the presence of TEVAR in a cohort of otherwise healthy subjects was related to dilation of the proximal aorta or increase in aortic stiffness and flow alterations.

Methods

Nineteen patients who underwent TEVAR implantation after a traumatic injury of the thoracic descending aorta (DAo) (10.0±6.1 years from intervention) and 44 healthy volunteers (HV) underwent 4D flow CMR to compute ascending aorta (AAo) pulse wave velocity (PWV), a marker of aortic stiffness, systolic flow reversal ratio (SFRR), quantifying backward flow during systole and in-plane rotational flow (IRF), measuring in-plane strength of helical flow. IRF and SFRR were assessed at 20 planes between the sinotubular junction and the mid thoracic DAo. Aortic diameters were measured using double-oblique cine CMR.

Results

Patients with TEVAR and HV did not differ in age, sex, body surface area, blood pressure and DAo diameter distal to TEVAR (Table). However, TEVAR patients presented larger diameters at the sinus of Valsalva and AAo, increased AAo PWV and strong flow alterations: IRF was reduced from the distal AAo to the proximal DAo, while SFRR was increased in the whole thoracic aorta (Figure).

Conclusions

In patients with blunt traumatic thoracic aortic injury treated with TEVAR the aorta proximal to TEVAR is dilated, stiffer and present potentially pathogenic flow conditions. Longitudinal studies are needed to assess whether these alterations have prognostic value and may improve clinical prevention and management of these patients.

Figure 1. IRF and SFRR in healthy vs TEVAR

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): This study has been funded by Instituto de Salud Carlos III, Spanish Ministry of Science and Innovation (PI19/01480). Guala A. received funding from the Spanish Ministry of Science, Innovation and Universities (IJC2018-037349-I).

Leukocyte Profiles Reflect Geographic Range Limits in a Widespread Neotropical Bat

Quantifying how the environment shapes host immune defense is important for understanding which wild populations may be more susceptible or resistant to pathogens. Spatial variation in parasite risk, food and predator abundance, and abiotic conditions can each affect immunity, and these factors can also manifest at both local and biogeographic scales. Yet identifying predictors and the spatial scale of their effects is limited by the rarity of studies that measure immunity across many populations of broadly distributed species. We analyzed leukocyte profiles from 39 wild populations of the common vampire bat (Desmodus rotundus) across its wide geographic range throughout the Neotropics. White blood cell differentials varied spatially, with proportions of neutrophils and lymphocytes varying up to six-fold across sites. Leukocyte profiles were spatially autocorrelated at small and very large distances, suggesting that local environment and large-scale biogeographic factors influence cellular immunity. Generalized additive models showed that bat populations closer to the northern and southern limits of the species range had more neutrophils, monocytes, and basophils, but fewer lymphocytes and eosinophils, than bats sampled at the core of their distribution. Habitats with access to more livestock also showed similar patterns in leukocyte profiles, but large-scale patterns were partly confounded by time between capture and sampling across sites. Our findings suggest that populations at the edge of their range experience physiologically limiting conditions that predict higher chronic stress and greater investment in cellular innate immunity. High food abundance in livestock-dense habitats may exacerbate such conditions by increasing bat density or diet homogenization, although future spatially and temporally coordinated field studies with common protocols are needed to limit sampling artifacts. Systematically assessing immune function and response over space will elucidate how environmental conditions influence traits relevant to epidemiology and help predict disease risks with anthropogenic disturbance, land conversion, and climate change.

Fluorescent biomarkers demonstrate prospects for spreadable vaccines to control disease transmission in wild bats

Vaccines that autonomously transfer among individuals have been proposed as a strategy to control infectious diseases within inaccessible wildlife populations. However, rates of vaccine spread and epidemiological efficacy in real-world systems remain elusive. Here, we investigate whether topical vaccines that transfer among individuals through social contacts can control vampire bat rabies-a medically and economically important zoonosis in Latin America. Field experiments in three Peruvian bat colonies, which used fluorescent biomarkers as a proxy for the bat-to-bat transfer and ingestion of an oral vaccine, revealed that vaccine transfer would increase population-level immunity up to 2.6 times beyond the same effort using conventional, non-spreadable vaccines. Mathematical models showed that observed levels of vaccine transfer would reduce the probability, size and duration of rabies outbreaks, even at low but realistically achievable levels of vaccine application. Models further predicted that existing vaccines provide substantial advantages over culling bats-the policy currently implemented in North, Central and South America. Linking field studies with biomarkers to mathematical models can inform how spreadable vaccines may combat pathogens of health and conservation concern before costly investments in vaccine design and testing.

Demographic and environmental drivers of metagenomic viral diversity in vampire bats

Viruses infect all forms of life and play critical roles as agents of disease, drivers of biochemical cycles and sources of genetic diversity for their hosts. Our understanding of viral diversity derives primarily from comparisons among host species, precluding insight into how intraspecific variation in host ecology affects viral communities or how predictable viral communities are across populations. Here we test spatial, demographic and environmental hypotheses explaining viral richness and community composition across populations of common vampire bats, which occur in diverse habitats of North, Central and South America. We demonstrate marked variation in viral communities that was not consistently predicted by a null model of declining community similarity with increasing spatial or genetic distances separating populations. We also find no evidence that larger bat colonies host greater viral diversity. Instead, viral diversity follows an elevational gradient, is enriched by juvenile-biased age structure, and declines with local anthropogenic food resources as measured by livestock density. Our results establish the value of linking the modern influx of metagenomic sequence data with comparative ecology, reveal that snapshot views of viral diversity are unlikely to be representative at the species level, and affirm existing ecological theories that link host ecology not only to single pathogen dynamics but also to viral communities.

Using noninvasive metagenomics to characterize viral communities from wildlife

Microbial communities play an important role in organismal and ecosystem health. While high-throughput metabarcoding has revolutionized the study of bacterial communities, generating comparable viral communities has proven elusive, particularly in wildlife samples where the diversity of viruses and limited quantities of viral nucleic acid present distinctive challenges. Metagenomic sequencing is a promising solution for studying viral communities, but the lack of standardized methods currently precludes comparisons across host taxa or localities. Here, we developed an untargeted shotgun metagenomic sequencing protocol to generate comparable viral communities from noninvasively collected faecal and oropharyngeal swabs. Using samples from common vampire bats (Desmodus rotundus), a key species for virus transmission to humans and domestic animals, we tested how different storage media, nucleic acid extraction procedures and enrichment steps affect viral community detection. Based on finding viral contamination in foetal bovine serum, we recommend storing swabs in RNAlater or another nonbiological medium. We recommend extracting nucleic acid directly from swabs rather than from supernatant or pelleted material, which had undetectable levels of viral RNA. Results from a low-input RNA library preparation protocol suggest that ribosomal RNA depletion and light DNase treatment reduce host and bacterial nucleic acid, and improve virus detection. Finally, applying our approach to twelve pooled samples from seven localities in Peru, we showed that detected viral communities saturated at the attained sequencing depth, allowing unbiased comparisons of viral community composition. Future studies using the methods outlined here will elucidate the determinants of viral communities across host species, environments and time.

Tumor de células gigantes espinal en niños. Reporte de dos casos. [Spinal giant cell tumor in children. Report of two cases]

El tumor de células gigantes espinal es una neoplasia de estirpe benigna y comportamiento local agresivo, de presentación rara en la población pediátrica. El dolor asociado al compromiso neurológico es la presentación típica en niños. La resección amplia del tumor y la descompresión de los elementos neurales asociada a fusión instrumentada permiten obtener una columna estable, preservar o restaurar la función neural y evitar la recidiva tumoral. Se presentan dos pacientes con tumor de células gigantes espinal en esqueleto inmaduro, sometidos a resección y estabilización mediante artrodesis instrumentada, sin recidiva en el posoperatorio alejado. La presentación clínica, la edad de los pacientes y los resultados quirúrgicos a largo plazo hacen de extremo valor el reporte de estos casos en esqueletos inmaduros.

Extended-spectrum beta-lactamase-producing Escherichia coli in common vampire bats Desmodus rotundus and livestock in Peru

Antibiotic resistance mediated by bacterial production of extended-spectrum beta-lactamase (ESBL) is a global threat to public health. ESBL resistance is most commonly hospital-acquired; however, infections acquired outside of hospital settings have raised concerns over the role of livestock and wildlife in the zoonotic spread of ESBL-producing bacteria. Only limited data are available on the circulation of ESBL-producing bacteria in animals. Here, we report ESBL-producing Escherichia coli in wild common vampire bats Desmodus rotundus and livestock near Lima, Peru. Molecular analyses revealed that most of this resistance resulted from the expression of bla_CTX-M-15 genes carried by plasmids, which are disseminating worldwide in hospital settings and have also been observed in healthy children of Peru. Multilocus sequence typing showed a diverse pool of E. coli strains carrying this resistance that were not always host species-specific, suggesting sharing of strains between species or infection from a common source. This study shows widespread ESBL resistance in wild and domestic animals, supporting animal communities as a potential source of resistance. Future work is needed to elucidate the role of bats in the dissemination of antibiotic-resistant strains of public health importance and to understand the origin of the observed resistance.

On the complexity of clinical and molecular bases of neurodegeneration with brain iron accumulation

Neurodegeneration with brain iron accumulation (NBIA) is a group of inherited heterogeneous neurodegenerative rare disorders. These patients present with dystonia, spasticity, parkinsonism and neuropsychiatric disturbances, along with brain magnetic resonance imaging (MRI) evidence of iron accumulation. In sum, they are devastating disorders and to date, there is no specific treatment. Ten NBIA genes are accepted: PANK2, PLA2G6, C19orf12, COASY, FA2H, ATP13A2, WDR45, FTL, CP, and DCAF17; and nonetheless, a relevant percentage of patients remain without genetic diagnosis, suggesting that other novel NBIA genes remain to be discovered. Overlapping complex clinical pictures render an accurate differential diagnosis difficult. Little is known about the pathophysiology of NBIAs. The reported NBIA genes take part in a variety of pathways: CoA synthesis, lipid and iron metabolism, autophagy, and membrane remodeling. The next-generation sequencing revolution has achieved relevant advances in genetics of Mendelian diseases and provide new genes for NBIAs, which are investigated according to 2 main strategies: genes involved in disorders with similar phenotype and genes that play a role in a pathway of interest. To achieve an effective therapy for NBIA patients, a better understanding of the biological process underlying disease is crucial, moving toward a new age of precision medicine.

Arabidopsis COGWHEEL1 links light perception and gibberellins with seed tolerance to deterioration

Light is a major regulator of plant growth and development by antagonizing gibberellins (GA), and we provide evidence for a role of light perception and GA in seed coat formation and seed tolerance to deterioration. We have identified two activation-tagging mutants of Arabidopsis thaliana, cog1-2D and cdf4-1D, with improved seed tolerance to deterioration linked to increased expression of COG1/DOF1.5 and CDF4/DOF2.3, respectively. These encode two homologous DOF transcription factors, with COG1 most highly expressed in seeds. Improved tolerance to seed deterioration was reproduced in transgenic plants overexpressing these genes, and loss of function from RNA interference resulted in opposite phenotypes. Overexpressions of COG1 and CDF4 have been described to attenuate various light responses mediated by phytochromes. Accordingly, we found that phyA and phyB mutants exhibit increased seed tolerance to deterioration. The phenotype of tolerance to deterioration conferred by gain of function of COG1 and by loss of function of phytochromes is of maternal origin, is also observed under natural aging conditions and correlates with a seed coat with increased suberin and reduced permeability. In developing siliques of the cog1-2D mutant the expression of the GA biosynthetic gene GA3OX3 and levels of GA1 are higher than in the wild type. These results explain the antagonism between phytochromes and COG1 in terms of the inhibition and the activation, respectively, of GA action.

New records of pigmentation disorders in molossid and phyllostomid (Chiroptera) bats from Peru

Pigmentation disorders, either from the complete absence (albinism), partial (leucism), or excess (melanism) of melanin, are rare in vertebrates. Worldwide, only a few records of these disorders had been reported for bats. Thanks to recent fieldwork and examination of museum specimens of the collections of the AMNH and MUSM, we report five species with those conditions in Peru. In this study, we report the first cases of leucism in

Baseline mean deviation and rates of visual field change in treated glaucoma patients

PURPOSE

To evaluate the relationships between baseline visual field (VF) mean deviation (MD) and subsequent progression in treated glaucoma.

METHODS

Records of patients seen in a glaucoma practice between 1999 and 2009 were reviewed. Patients with glaucomatous optic neuropathy, baseline VF damage, and ≥8 SITA-standard 24-2 VF were included. Patients were divided into tertiles based upon baseline MD. Automated pointwise linear regression determined global and localized rates (decibels (dB) per year) of change. Progression was defined when two or more adjacent test locations in the same hemifield showed a sensitivity decline at a rate of >1.0  dB per year, P<0.01.

RESULTS

For mild, moderate, and severe groups, progression was noted in 29.5, 31.2, and 26.0% of eyes (P=0.50) and global rates of VF change of progressing eyes were -1.3±1.2, -1.01±0.7, and -0.9±0.5 dB/year (P=0.09, analysis of variance). Within these groups, intraocular pressure (IOP) in stable vs progressing eyes were 15.5±3.3 vs 17.0±3.1 (P<0.01), 15.4±3.3 vs 15.9±2.5 (P=0.28), and 14.0±2.8 vs 14.8±2.3 mm Hg (P=0.07). More glaucoma filtering surgeries were performed in eyes with worse MD. There was no significant difference between groups regarding their risk of progression in both univariate (P=0.50) and multivariate (P=0.26) analyses adjusting for differences in follow-up IOP.

CONCLUSIONS

After correcting for differences in IOP in treated glaucoma patients, we did not find a relationship between the rate of VF change (dB per year) and the severity of the baseline VF MD. This finding may have been due to more aggressive IOP lowering in eyes with more severe disease. Eyes with lower IOP progressed less frequently across the spectrum of VF loss.

Axial length and optic disc size in normal eyes

AIM

To investigate the relationship between optic disc area and axial length in normal eyes of white and black people.

METHODS

Consecutive eligible normal subjects were enrolled. Ocular biometry was obtained using A-scan ultrasonography, and reliable images of the optic disc were obtained using a confocal scanning laser ophthalmoscope. The relationship between optic disc area and axial length was assessed using univariate and multivariate models.

RESULTS

281 eyes of 281 subjects were enrolled. Black subjects (n = 157) had significantly larger discs (mean (SD) disc area, 2.12 (0.5) mm(2)) than white subjects (n = 124; 1.97 (0.6) mm(2); t test, p = 0.02). Optic disc area increased with axial length (Pearson's correlation coefficient, r = 0.13, p<0.035) for the entire study population. Multivariate regression models including race, disc area and axial length showed that a significant but weak linear relationship exists between axial length and disc area (partial correlation coefficient 0.14; p<0.024), and with race and disc area (partial correlation coefficient 0.19; p<0.017) when adjusted for the effects of other terms in the model.

CONCLUSION

Increased disc area is associated with longer axial length measurements and African ancestry. This may have implications for pathophysiology and risk assessment of glaucoma.

Urrets-Zavalia syndrome as a complication of argon laser peripheral iridoplasty

OBJECTIVE

To report on 8 patients who developed prolonged mydriasis after argon laser peripheral iridoplasty (ALPI).

DESIGN

Retrospective case series.

METHODS

A review of the charts of 8 patients with persistent occludable angles after laser iridotomy who developed mydriasis after undergoing ALPI.

RESULTS

12 eyes of 8 patients (mean age 50.2, standard deviation 6.9, range 40-61 years) developed persistent dilatation. 7 of 8 patients had plateau iris syndrome. Only one patient had a decrease in visual acuity. Intraocular pressure increased only in 1 eye and remained stable or decreased in the others. Of the 8 patients, 7 had blurred vision, 2 had photophobia, 4 had glare and 1 had discomfort. The pupillary response to pilocarpine instillation was minimal or absent. Mydriasis eventually resolved in all eyes without treatment.

CONCLUSION

ALPI can be complicated by mydriasis unresponsive to pilocarpine. Mydriasis and accompanying symptoms resolved spontaneously within 1 year in most patients.

Detection of glaucoma using operator-dependent versus operator-independent classification in the Heidelberg retinal tomograph-III

OBJECTIVE

To compare the abilities of a new Glaucoma Probability Scoring (GPS) system and Moorfields regression analysis (MRA) to differentiate between glaucomatous and normal eyes using Heidelberg retinal tomograph (HRT)-III software and race-specific databases.

METHODS

In this prospective study, one eye (refractive error < or =5 D) each of consecutive normal patients and those with glaucoma was enrolled. All patients underwent a full eye examination, standard achromatic perimetry (Swedish Interactive Threshold Algorithm-standard automated perimetry (SITA-SAP), program 24-2) and confocal scanning laser ophthalmoscopy (HRT-II) within 1 month. Normal patients had two normal visual fields in both eyes (pattern standard deviation (PSD) >5% and Glaucoma Hemifield Test within 97% normal limits) and a normal clinical examination. Glaucoma was defined on the basis of SITA-SAP visual field loss (PSD<5% or Glaucoma Hemifield Test outside normal limits) on two consecutive visual fields. HRT-II examinations were exported to the HRT-III software (V.3.0), which uses an enlarged race-specific database, consisting of 733 eyes of white people and 215 eyes of black people. Race-adjusted MRA for the most abnormal sector (operator-dependent contour line placement) was compared with the global race-adjusted GPS (operator independent). MRA sectors outside the 99.9% confidence interval limits (outside normal limits) and GPS > or =0.64 were considered abnormal.

RESULTS

136 normal patients (72 black and 64 white patients) and 84 patients with glaucoma (52 black and 32 white patients) were enrolled (mean age 50.4 (SD 14.4) years). The average visual field mean deviation was (-)0.4 (SD 1.1) db for the normal group and (-)7.3 (SD 6.7) db for the glaucoma group (p<0.001). Mean GPS values were 0.21 (SD 0.23) and 0.73 (SD 0.27) for normal and glaucomatous eyes, respectively (p<0.001). Sensitivity and specificity values were 77.1% and 90.3% for GPS, and 71.4% and 91.9% for MRA, respectively.

CONCLUSIONS

In this cohort, GPS software sensitivity and specificity values are similar to those of MRA, which requires placement of an operator-dependent contour line. The development of software to detect glaucoma without a contour line is critical to improving the potential use of HRT as a tool for glaucoma detection and screening.

Effect of a tight necktie on intraocular pressure

AIM

To evaluate the effect of a tight necktie on intraocular pressure (IOP) measurement using Goldmann applanation tonometry.

METHODS

40 eyes of 20 normal subjects and 20 open angle glaucoma patients (all male) were enrolled. IOP was measured with an open shirt collar, 3 minutes after placing a tight necktie, and 3 minutes after loosening it. All measurements were made by the same examiner.

RESULTS

Mean IOP in normal subjects increased by 2.6 (SD 3.9) mm Hg (p=0.008, paired t test; range -3 to +14 mm Hg) and in glaucoma patients by 1.0 (1.8) mm Hg (p=0.02, paired t test; range -2 to +4.5 mm Hg). In normal subjects, IOP in 12 eyes was increased by >/=2 mm Hg and in seven eyes by >/=4 mm Hg. In glaucoma patients, IOP in six eyes was increased by >/=2 mm Hg and in two eyes by >/=4 mm Hg.

CONCLUSION

A tight necktie increases IOP in both normal subjects and glaucoma patients and could affect the diagnosis and management of glaucoma.

Ultrasound biomicroscopy before and after goniosynechialysis

PURPOSE

To report the ultrasound biomicroscopic appearance of the anterior chamber angle before and after successful goniosynechialysis.

METHODS

Interventional case report. Ultrasound biomicroscopy using a 50-MHz transducer was performed in the supine position preoperatively and postoperatively in a 76-year-old woman with angle-closure glaucoma.

RESULTS

Ultrasound biomicroscopy of the anterior chamber angle demonstrated restoration of an open anterior chamber angle after goniosynechialysis.

CONCLUSION

High-resolution imaging of the anterior segment to evaluate preoperative and postoperative anatomy may be useful in eyes undergoing goniosynechialysis.

Aqueous misdirection after glaucoma drainage device implantation

OBJECTIVE

To describe the clinical presentation, outcome, and possible underlying mechanism of aqueous misdirection after glaucoma drainage device implantation.

DESIGN

Retrospective, noncomparative, interventional case series.

PARTICIPANTS

Ten eyes (five primary open-angle glaucoma, four chronic angle-closure glaucoma, one nanophthalmos) of nine patients with a mean age of 68.5+/-12.0 years (range, 43-83 years).

INTERVENTION

The authors reviewed the medical records of all patients with a clinical diagnosis of aqueous misdirection after Baerveldt glaucoma drainage device implantation at two tertiary care referral centers from October 1992 to October 1997. Surgery was performed in a standardized fashion; all drainage tubes were inserted in the anterior chamber and occluded with an external 7-0 polyglactin ligature. All eyes were treated with topical corticosteroids, cycloplegia, and aqueous suppressants. Eyes with persistent aqueous misdirection received neodymium:YAG (Nd:YAG) hyaloidotomy or pars plana vitrectomy.

MAIN OUTCOME MEASURES

Visual acuity, intraocular pressure, biomicroscopic anterior chamber depth, and antiglaucomatous medication.

RESULTS

All eyes had axial shallowing of the anterior chamber, one or more patent iridotomies, and no ophthalmoscopic or B-scan ultrasonographic evidence of serous or hemorrhagic ciliochoroidal detachment. Median time to the development of angle-closure glaucoma was 33.5 days (range, 1-343 days) and mean intraocular pressure at diagnosis was 27.7+/-18.7 mm Hg (range, 10-62 mm Hg). Normalization of anterior segment anatomy was achieved with aqueous suppression and cycloplegia (one eye); Nd:YAG capsulotomy (four eyes); pars plana vitrectomy alone (two eyes) or with lensectomy (one eye), and pars plana vitrectomy with intraocular lens explanation (two eyes). Mean final intraocular pressure was 14.1+/-6.0 mmHg at a mean follow-up of 9.1+/-7.8 months after the development of aqueous misdirection (range, 1-23 months).

CONCLUSIONS

Aqueous misdirection may develop days to months after glaucoma drainage device implantation. In this series, there was a poor response to medical therapy, and normalization in anterior chamber depth required aggressive laser and surgical therapy.

High-resolution ultrasound biomicroscopy of the pars plana and peripheral retina

OBJECTIVE

This study aimed to evaluate the ability and role of ultrasound biomicroscopy in imaging the peripheral retina, pars plana, and anterior choroid.

DESIGN

The study design was a case series.

PARTICIPANTS

Seventeen eyes of 17 patients with a variety of clinical diagnoses involving the anterior portion of the posterior segment were studied.

INTERVENTION

High-frequency (50 MHz), high-resolution (50 microns) ultrasound biomicroscopy was performed.

RESULTS

Ultrasound biomicroscopy was capable of imaging the peripheral retina, pars plana, and anterior choroid. Images had features consistent with known histopathology. Retinoschisis consisted of one thin hyper-reflective echo and could be differentiated from a retinal detachment, which was thicker and formed a bilayered echo. A choroidal effusion could be identified as an echolucent space within the suprachoroidea, whereas a choroidal hemorrhage was moderately echodense. Inflammatory diseases, such as a sarcoid granuloma, pars planitis, and Harada's disease, were characterized by different forms of uveal thickening. A ciliochoroidal nevus was internally hyporeflective and could be measured accurately and localized.

CONCLUSIONS

Imaging of the peripheral retina, pars plana, and anterior choroid is possible with ultrasound biomicroscopy and may aid in the diagnosis and management of pathology involving this region.

Ultrasound biomicroscopy in anterior ocular trauma

BACKGROUND AND OBJECTIVE

The authors investigated the role of ultrasound biomicroscopy after ocular trauma.

PATIENTS AND METHODS

Ultrasound biomicroscopy was performed in six eyes of six patients at the New York Eye and Ear Infirmary after a variety of traumatic ocular injuries.

RESULTS

Eyes with angle recession, iridodialysis, cyclodialysis, hyphema, an intraocular foreign body, scleral laceration, and subluxed crystalline lens were imaged without complication. Ultrasound biomicroscopy aided in the diagnosis when visualization was limited by media opacities or distorted anterior segment anatomy.

CONCLUSION

Ultrasound biomicroscopy is a safe and effective adjunctive tool for the clinical assessment and management of ocular trauma, especially when visualization is limited and multiple traumatic injuries are involved.

[Alkaline encrusted cystitis secondary to Proteus mirabilis infection in a HIV infected patient]

We described for the first time an alkaline encrusting cystitis in a patient with the acquired immune deficiency. This is an entity characterized by severe dysuria and long standing urinary frequency, alkaline urine and radiographically visible calcification of the urinary bladder. It has been observed in patients with permanent Foley catheter, persistent infections due to microorganisms with urolytic activity, urinary bilharziosis or tuberculosis, or malignant bladder tumors. None of these entities were described and the patient had all conditions for this syndrome.

Ciliary body enlargement and cyst formation in uveitis

BACKGROUND

Acute anterior uveitis has diverse causes and systemic associations. Inflammation is predominantly localised to the iris and pars plicata. Little is known about the in vivo effects of uveitis on ciliary body anatomy.

METHODS

Bilateral, high frequency, high resolution, ultrasound biomicroscopy was performed on consecutive patients with unilateral anterior uveitis to evaluate ciliary body anatomy. Imaging was repeated when possible during the clinical course. The cross sectional area of the anterior ciliary body was measured using image processing and analysis software. Measurements from the uveitic eyes were compared with the fellow eyes and the effect of treatment was evaluated.

RESULTS

Fourteen patients were enrolled. Ultrasound biomicroscopy demonstrated a larger ciliary body cross sectional area in the uveitic eyes compared with the fellow, clinically uninvolved eyes (2.45 (SD 0.48) mm2 versus 1.55 (SD 0.15) mm2, (p = 0.0000; paired t test)). A ciliochoroidal effusion was present in one uveitic eye. Epithelial cysts were imaged bilaterally in four uveitic patients (29%) and unilaterally in unaffected eyes of two uveitic patients. Ciliary body cross sectional area decreased following steroid therapy (p = 0.0001; paired t test). New cysts were noted in three uveitic eyes during the follow up period and in none of the fellow, unaffected eyes.

CONCLUSION

Ultrasound biomicroscopy offers a new approach to the evaluation of anterior uveitis. The response to treatment can be evaluated objectively and therapeutic efficacy can be more easily assessed. It has the potential to help elucidate the pathophysiology and anatomical changes of this heterogeneous group of disorders.

In vivo increase of the human lens equatorial diameter during accommodation

The movement of the human lens equator during accommodation was examined in vivo. High-resolution ultrasound images of the lens equator were obtained from young human subjects whose amplitude of accommodation was controlled with 1% tropicamide and 2% pilocarpine. To avoid errors that otherwise arise from eye rotation or other movement, the cornea and sclera were used as positional references in comparative studies of the video images obtained from the unaccommodated and accommodated states. During accommodation, the movement at the lens equator involved small displacement; i.e., < 100 microns, and the equator did not move anteriorly or posteriorly but peripherally toward the sclera. These results indicate that the lens equator is under increased zonular tension during accommodation, in contradiction to Helmholtz's widely accepted theory of accommodation.

Giant cell arteritis: diagnosis and management

Giant cell arteritis should not be a diagnosis of exclusion, an afterthought, or a last thought. There is urgency to establishing this diagnosis and initiating therapy. All practitioners who treat adults will be confronted with these patients. Some will have classic presentations, some will have subtle presentations. When patients complain of fever, fatigue, malaise, weight loss, or painless vision loss, GCA should be suspected. An ESR will aid in the diagnosis (although a normal ESR does not rule it out), and sometimes temporal artery biopsy will provide certainty. Giant cell arteritis is usually easy to recognize, easy to treat, and satisfying to manage.

Reduced trabecular meshwork height in juvenile primary open-angle glaucoma

OBJECTIVE

To compare trabecular meshwork height in a series of patients with juvenile primary open-angle glaucoma (JPOAG) with that in normal control patients.

METHODS

Ultrasound biomicroscopy and A-scan biometry were performed on 16 eyes with JPOAG and 24 normal eyes. A radial, perpendicular image in the horizontal temporal meridian detailing the line of Schwalbe, scleral spur, and angle anatomy was obtained for each eye by a single examiner. Trabecular meshwork height was defined as the distance from the scleral spur to the Schwalbe line.

RESULTS

Mean patient age (P = .85, t test), refractive error (P = .68), sex distribution (P = .26, Fisher exact test) and axial length (P = .39) were similar between the groups. Mean +/- SE trabecular meshwork heights were 0.36 +/- 0.03 mm (range, 0.19-0.53 mm) for JPOAG and 0.58 +/- 0.02 mm (range, 0.40-0.80 mm) for controls (P < .001). Eyes with greater axial length tended to have larger trabecular meshworks in both groups (P = .012, multivariate regression). A trabecular meshwork height-axial length ratio of 0.021 or less was associated with a significantly increased risk for JPOAG being present (odds ratio, 57; 95% confidence interval, 6.0-541).

CONCLUSIONS

The trabecular meshwork is smaller in eyes with JPOAG compared with that in normal eyes. This finding suggests a structural abnormality that may underlie the reduced outflow.

Repair of Descemet's membrane detachment with the assistance of intraoperative ultrasound biomicroscopy

PURPOSE

To evaluate the ability of ultrasound biomicroscopy to monitor the repair of large Descemet's membrane detachments.

METHODS

Intraoperative ultrasound biomicroscopy was performed in two patients who had undergone previous unsuccessful surgical repair of large Descemet's membrane detachments.

RESULTS

Ultrasound biomicroscopy visualized and located Descemet's membrane detachment and verified proper suture placement and membrane repositioning.

CONCLUSIONS

Ultrasound biomicroscopy is a useful tool to guide surgical repair of Descemet's membrane detachments, particularly when hazy media prevent satisfactory visualization.

Risk factors for ciliochoroidal effusion after panretinal photocoagulation

PURPOSE

To determine the incidence, duration, and risk factors for ciliochoroidal effusion after panretinal photocoagulation.

METHODS

Thirty-nine consecutive patients with diabetic retinopathy underwent ultrasound biomicroscopy of both eyes to image the ciliochoroidal space immediately before and 1 day after unilateral argon-green panretinal photocoagulation. Imaging was repeated on days 3, 7, and 14 in patients in whom ciliochoroidal effusion developed.

RESULTS

Low-lying ciliochoroidal effusions were imaged in 23 (59%) of 39 eyes. Of 23 eyes, effusions resolved in 6 (26%), 12 (52%), and 5 (22%) eyes by 3, 7, and 14 days respectively. The number of laser applications (P = 0.02), shorter axial length (P = 0.01), and percentage of retinal surface area treated (P = 0.02) were associated with systemic hypertension, location of treatment, previous panretinal photocoagulation of cataract surgery, retinal surface area treated, and mean blood pressure before photocoagulation were not associated with effusion. All fellow, untreated eyes remained effusion-free.

CONCLUSION

Ciliochoroidal effusion develops commonly after panretinal photocoagulation. Limiting the number of laser applications and the percentage of retinal surface area treated reduces the likelihood of this complication. Eyes with shorter axial lengths are at higher risk

Personal computer-based 3-dimensional ultrasound biomicroscopy of the anterior segment

OBJECTIVE

To develop a practical, inexpensive system for 3-dimensional ultrasound biomicroscopic imaging of the anterior segment with a commercially available high-frequency ultrasound imager and a personal computer.

METHODS

Sequential, high-frequency, ultrasound biomicroscopic images of the anterior segment were obtained with a motorized scanning control arm designed in our imaging laboratory. Images were acquired by a personal computer-based video capture device. Ultrasound slice data were then reconstructed as 3-dimensional volumetric images by a personal computer and commercially available software.

RESULTS

Four 3-dimensional visualization formats were developed to enhance the clinical utility of high-frequency ultrasound. Rotational animation sequences were created that detailed the extent and anatomy of a filtering bleb, intraocular lens subluxation, focal angle closure from an iridociliary cyst, intraocular foreign bodies, and an iris tumor.

CONCLUSIONS

Three-dimensional, high-frequency ultrasound of the anterior segment enhances our ability to visualize spatial relationships between adjacent anatomic structures. The low cost and ease of use of this system make widespread clinical application practical.

Diagnosis of traumatic cyclodialysis by ultrasound biomicroscopy

BACKGROUND AND OBJECTIVE

To evaluate the ability of high-frequency ultrasound biomicroscopy to diagnose traumatic cyclodialyses not evident on clinical examination.

PATIENTS AND METHODS

Six eyes to six patients with posttraumatic hypotony and/or shallow anterior chamber and suspected cyclodialysis clefts were examined with slit-lamp biomicroscopy, gonioscopy, B-scan ultrasonography, and ultrasound biomicroscopy. Ultrasound biomicroscopy provided high resolution of cross-sectional images of the anterior chamber angle, posterior chamber, and anterior uveal tissue.

RESULTS

Ultrasound biomicroscopy confirmed the disinsertion of the ciliary body from the scleral spur and associated ciliary body detachment in all eyes. Gonioscopy failed to demonstrate a cyclodialysis cleft in five eyes because of hyphema (two eyes) and abnormal iris architecture (related to trauma) precluding visualization of the angle recess (three eyes). Using information from ultrasound biomicroscopy imagining, one patient underwent a ciliary body reattachment procedure and repair of the cyclodialysis cleft.

CONCLUSION

Ultrasound biomicroscopy is a noninvasive method that can accurately diagnose the presence of traumatic cyclodialyses and can aid in surgical management. It is particularly useful in the presence of hazy media, hypotony, and/or abnormal anterior segment anatomy.

Ultrasound Biomicroscopy of Intrastromal Photorefractive Keratectomy With the Nd:YLF Picosecond Laser

PURPOSE

To evaluate corneal morphology in vivo following intrastromal photorefractive keratectomy (IPRK) with the Nd:YLF picosecond laser, using the ultrasound biomicroscope.

MATERIALS AND METHODS

Myopic intrastromal PRK was performed in the anterior stroma of cat corneas with the neodymium:yttrium lithium fluoride (Nd:YLF) picosecond laser. Periodic examination of the treated corneas up to 6 months postoperative was performed with high resolution ultrasound biomicroscopy. Corneal thickness, depth of the laser patterns from the corneal surface, alignment of the laser treatment, extent of stromal opacification until resolution, and contour of the corneal surface were measured with the ultrasound biomicroscope throughout follow up.

RESULTS

The treated corneas were thickened on ultrasonic biomicroscopy measurement immediately after intrastromal PRK and revealed a densely echogenic shadow parallel to the corneal surface at the treatment site. There was increased stromal echogenicity denoting mild edema. The echoes decreased over time and appeared thinner at 2 months compared to the preoperative and immediate postoperative measurements. At 6-month follow up, the treated corneas were echolucent on ultrasonic biomicroscopy.

CONCLUSION

The ultrasound biomicroscope might become a helpful tool in assessing accuracy of treatment parameters of intrastromal PRK as well as in monitoring the response of the cornea to treatment.

Epithelial inclusion cyst of the iris

We describe the clinical presentation, high-frequency ultrasound biomicroscopic characteristics, and pathologic findings associated with a conjunctival inclusion cyst within the iris. The patient had undergone an uncomplicated extracapsular cataract extraction with posterior chamber intraocular lens insertion 9 months prior to presenting with a progressively enlarging iris mass. A clinical examination revealed a solid-appearing white tumor within the midiris stroma, accompanied by limbal-conjunctival hyperemia and anterior chamber inflammation. Ultrasound biomicroscopy revealed an egg-shaped solid iris stromal tumor that displaced the pigment epithelium. The mass was composed of three concentric layers of different echogenicity: a moderately reflective mantle, a less reflective middle zone, and a hyperreflective core. Within 3 days of initiation of topical corticosteroid therapy (prednisolone acetate, 0.5 mg per drop four times daily), the tumor enlarged and induced a plasmoid aqueous and a hypopyon. Histopathologic study revealed a conjunctival inclusion cyst with evidence of acute and chronic inflammation. We have found that the diagnosis of epithelial inclusion cyst within the iris can be aided by an ultrasound evaluation. This case also suggests that it may be preferable to excise these tumors prior to topical corticosteroid treatment.

Prevention of blinking alters iris configuration in pigment dispersion syndrome and in normal eyes

PURPOSE

To examine the effect of blinking on iris configuration and aqueous humor distribution between the posterior and anterior chambers in eyes with pigment dispersion syndrome compared with healthy eyes.

METHODS

High-resolution, anterior segment ultrasound biomicroscopy was performed on ten eyes of ten patients with untreated pigment dispersion syndrome and on ten control subjects. Patients were scanned continuously for 15 minutes or until the maximal change in iris configuration occurred. During this time, the eyelids were held open mechanically, and blinking was prevented. Eyes then were rescanned immediately after blinking.

RESULTS

Initial iris configuration was concave in all eyes with pigment dispersion syndrome, whereas in control eyes it was concave in four eyes, planar in four eyes, and convex in two eyes. Iridozonular contact occurred in eyes with pigment dispersion syndrome only. Iridolenticular contact was greater in eyes with pigment dispersion syndrome than in control eyes. Analysis of covariance controlling for age, sex, and refractive error showed pigment dispersion syndrome to be a significant predictor of increased iris concavity. During continuous scanning, the mean change in iris position, from most concave to most convex, and mean time to the maximal change in iris configuration were greater for eyes with pigment dispersion syndrome than in control eyes and were related to the degree of initial iris concavity only (analysis of covariance). In six eyes with pigment dispersion syndrome, the eye cup was removed, normal blinking was permitted, and the eye was rescanned. The iris resumed a concave configuration in all eyes.

CONCLUSION

Increased iris concavity in pigment dispersion syndrome appears to be related to increased iridolenticular contact. This creates an anatomic configuration that predisposes to reverse pupillary block. The accumulation of aqueous humor in the posterior chamber, when blinking is prevented, alters iris position in pigment dispersion syndrome and in healthy eyes and increases iridozonular and iridociliary-process distances while minimizing iridolenticular contact. Normal blinking appears to create transient vector forces which promote aqueous humor flow from the posterior to anterior chamber.

Measurement of ultrasound biomicroscopy images: intraobserver and interobserver reliability

PURPOSE

To evaluate intraobserver and interobserver reproducibility of measurement of images obtained during ultrasound biomicroscopy.

METHODS

Four anterior segment images of four normal patients were obtained by a single examiner. The measurements of three independent observers were compared to assess interobserver reproducibility in quantifying the images. Thirteen different anterior segment parameters were measured by each observer on each image. Intraobserver and interobserver reproducibility of measurement were assessed by calculating the coefficient of variation for each individual observer and by using the F test to detect a difference among observers.

RESULTS

Intraobserver reproducibility was high. Interobserver reproducibility for the measured parameters varied considerably and was affected by subjective interpretation of visualized anatomic landmarks.

CONCLUSIONS

The optimal parameters for quantitative ultrasound biomicroscopy require refinement. Measurements of alterable parameters are best measured presently by a single observer. Ultrasound biomicroscopy has the potential to elucidate anatomic relationships underlying much anterior segment disease, but caution in interpreting quantitative differences is warranted.