Investigation of chemical partitioning of 7Be, 210Pb and 137Cs and novel dating of road sediment by 210Po:210Pb disequilibrium method

A suite of road sediment and soil samples from a post-industrial city (Detroit, MI) were collected and analyzed for atmospherically-delivered ²¹⁰Pb, ²¹⁰Po, ⁷Be along with ²²⁶Ra and ¹³⁷Cs in the bulk and size-fractionated solid samples. From the measured atmospheric depositional fluxes of ⁷Be, ²¹⁰Po, and ²¹⁰Pb, the initial ²¹⁰Po/²¹⁰Pb activity ratio was quantified. In all samples, there is disequilibrium between ²¹⁰Po and ²¹⁰Pb, with a ²¹⁰Po/²¹⁰Pb activity ratio (AR) of <1.0, which is reported for the first time. Using the measured ²¹⁰Po/²¹⁰Pb AR, the average 'apparent age' of road sediment was found to be 146 ± 62 days. Using numerical modeling, it is predicted that the (²¹⁰Po/²¹⁰Pb) excess activity ratio will reach a 'dynamic equilibrium' value of ~0.59 over a period of >1 year. Results from a subset of samples that were sequentially extracted for exchangeable, carbonate, Fe-Mn oxide, organic and residual phases indicate the Fe-Mn oxide fraction was found to contain the largest fraction of ⁷Be and ²¹⁰Pb; however, the largest fraction of ²¹⁰Pb was associated with the residual phase and is attributed to complexation of ²¹⁰Pb with recalcitrant organic matter. This study shows that the natural tagging of ⁷Be and ²¹⁰Po-²¹⁰Pb pair via precipitation provides insights on the time scale of their mobility and adds a new dimension of time information on the pollutant-laden road sediment.

Investigation of self-attenuation of 210Pb (46 keV) gamma ray in sediment, certified reference material and high-density minerals: Implication to precise measurement of 210Pb

High resolution gamma spectrometry is one of the most widely used techniques in the measurements of environmental level 210Pb in sediment from coastal and freshwater environments and such measurements are needed to establish 210Pb chronology for the past 100-150 years. Precise measurement of 210Pb in sediment and soil requires appropriate self-absorption correction for its low-energy (46.5 keV) gamma radiation due to differences in the matrix between the sample and standard used to calibrate the instrument. Here we report a method that involves precise determination of 210Pb activity in sediment sample by calibrating the HPGe well detector with RGU-1-IAEA Certified Reference Material for well-defined geometries. A comparison of the 210Pb activity obtained from gamma-ray spectrometry with that obtained from alpha spectrometry via 210Po, using 209Po as yield tracer, indicates good agreement. We propose an empirical relation between the absolute efficiencies and packing densities of sample in a well-defined geometry (cylindrical counting vial) by affecting the count rate of 210Pb and its progenitor, 226Ra (via 214Pb and 214Bi). The effects of self-attenuation of 46.5 keV (210Pb), for naturally-occurring high-density minerals (apatite, titanite, monazite, and cerite) are evaluated. Specific activity of 210Pb on apatite measured by alpha and gamma spectrometry are compared. This study is relevant and useful for precise measurements of gamma-emitting environmental radionuclides such as 210Pb, 7Be, 137Cs as well as 226Ra.

210Po concentration in different size fractions of aerosol likely contribution from industrial sources

²¹⁰Po, being a highly radiotoxic isotope, could contribute to significant inhalation dose to humans. This study establishes the first set of atmospheric ²¹⁰Po data in aerosol samples collected across Kuwait. The primary focus of this study is to investigate spatio-temporal variability of atmospheric ²¹⁰Po and assess its sources, including anthropogenic contributions. Measurements of ²¹⁰Po in aerosols collected over a period of 23 months (January 2018-November 2019) from three different locations, i.e., a remote area (120 km) north of Kuwait City, Kuwait city and an industrial site (60 km from Kuwait City center). Specific activities of ²¹⁰Po were determined in 3 different size fractions (0.39-2.5 μm, 2.5-10 μm and ≥10 μm) and the highest activity was observed in the fine fraction (PM_{0.39- 2.5}) across all sampling stations during both the summer and winter seasons. The highest activities in all the size fractions were measured downwind of the Industrial site that houses oil refineries, cement factory and some other industries including a Power and Desalination Plant. In terms of temporal variations, higher summertime activities were observed across the spatial domain. Longer residence time of atmospheric ²²²Rn-produced ²¹⁰Pb resulting in lower scavenging of atmospheric ²¹⁰Pb, due to very little precipitation in summer, will result in higher atmospheric ²¹⁰Po.

Quantification of Po-210 and Pb-210 as tracer of sediment resuspension rate in a shallow riverine system: Case study from southeast Michigan, USA

Polonium-210 and Pb-210 were measured in surficial benthic sediments and particulate matter collected in sediment traps deployed at five different locations in the Clinton River, a dynamic system, in Lake St. Clair in Southeast Michigan to quantify the sediment resuspension rates and determine the particle residence time. The mean ²¹⁰Po_xs/²¹⁰Pb_xs activity ratio of suspended trap and surficial bottom sediments were 0.72 ± 0.12 (n = 16, range: 0.42-0.89) and 0.79 ± 0.15 (n = 15, range: 0.40-1.00) indicating that a major fraction of trapped material is from resuspended bottom sediments. Sediment resuspension rate calculated using a single box model approach yielded a resuspension rate of 0.1-1.0 g cm^-2 yr^-1 using ²¹⁰Po and 0.2-1.4 g cm^-2 yr^-1using ²¹⁰Pb. Particle residence time varied from 0.3 to 3.9 days using ²¹⁰Pb and 0.9-13.4 days for ²¹⁰Po. This present study indicates that sediment resuspension is considerably high in Clinton River and thus any decision on remedial action towards the restoration such as dredging, natural attenuation is challenging. This present study has direct relevance to the transport and resuspension of other sulfur group elements (Se, O, etc) and lithogenic elements (e.g., Th).

Contributions of artifactual materials to the toxicity of anthropogenic soils and street dusts in a highly urbanized terrain

A study was undertaken to test the hypothesis that the presence of fly ash and other artifactual materials (AMs) significantly increases the toxicity of urban soil and street dust. AMs were distinguished as artifacts (artificial particles > 2 mm in size), and particulate artifacts (≤2 mm in size); street dust was the <63 μm fraction of street sediments. Reference artifacts, street dusts, and topsoils representing different land use types in Detroit, Michigan were analyzed for miscellaneous radionuclides, trace elements, magnetic susceptibility (MS), and acetic acid-extractable (leachable) Pb. Background levels were established using native glacial sediments. Street sediments were found to have a roadside provenance, hence street dusts inherited their contamination primarily from local soils. All soils and dusts had radionuclide concentrations similar to background levels, and radiological hazard indices within the safe range. Artifacts, fly ash-impacted soils and street dusts contained elevated concentrations of toxic trace elements, which varied with land use type, but none produced a significant amount of leachable Pb. It is inferred that toxic elements in AMs are not bioavailable because they are occluded within highly insoluble materials. Hence, these results do not support our hypothesis. Rather, AMs contribute to artificially-elevated total concentrations leading to an overestimation of toxicity. MS increased with increasing total concentration, hence proximal sensing can be used to map contamination level, but the weak correlation between total and leachable Pb suggests that such maps do not necessarily indicate the associated biohazard. Home site soils with total Pb concentrations >500 mg kg^-1 were sporadically toxic. Thus, these results argue against street dust as the local cause of seasonally elevated blood-Pb levels in children. Lead-bearing home site soil tracked directly indoors to form house dust is an alternative exposure pathway.

Changes in the mercury isotopic composition of sediments from a remote alpine lake in Wyoming, USA

Mercury (Hg) deposition from the atmosphere has increased dramatically since 1850 and Hg isotope records in lake sediments can be used to identify changes in the sources and cycling of Hg. We collected a sediment core from a remote lake (Lost Lake, Wyoming, USA) and measured vertical variation of Hg concentration and isotopic composition as well as ²¹⁰Pb and ¹³⁷Cs activities to establish a chronology. We also analyzed vegetation and soil samples from the watershed which has a small ratio of watershed area to lake surface area (2.06). The Hg flux remains constant from ~1350 to 1850 before increasing steadily to modern values that are approximately four times pre-1850 values. The modern Hg isotopic composition preserved in the sediments is distinct from the Hg isotopic composition of pre-1850 samples with both δ²⁰²Hg and Δ¹⁹⁹Hg becoming progressively more positive through time, with shifts of +0.37‰ and +0.23‰ respectively. To explain temporal changes in δ²⁰²Hg, Δ¹⁹⁹Hg, and Hg concentration in the core segments, we estimated a present-day atmospheric endmember based on precipitation and snow samples collected near Lost Lake. The observed change in Hg isotopic values through time cannot be explained solely by addition of anthropogenic Hg with the isotopic composition that has been estimated by others for global anthropogenic emissions. Instead, the isotope variation suggests that the relative importance of redox transformations, whether in the atmosphere, within the lake, or both, have changed since 1850.

Comparison of the scavenging intensity, remineralization and residence time of 210Po and 210Pb at key zones (biotic, sediment-water and hydrothermal) along the East Pacific GEOTRACES transect

The contrasting geochemical behavior of two long-lived progeny of ²²²Rn (daughter product of ²²⁶Ra), ²¹⁰Po and ²¹⁰Pb, provide valuable insights on the extent of recycling of biogenic particulate matter and their preferential removal from the water column. We collected and analyzed 135 water samples from six vertical profiles for ²¹⁰Po and ²¹⁰Pb as well as a suite of aerosol samples for ²¹⁰Pb along the US GEOTRACES East Pacific Zonal Transect (GP16). Calculated atmospheric depositional flux of ²¹⁰Pb from the measured ²¹⁰Pb activity in aerosols exhibits an overall decrease from east to west along the cruise track. The inventories of ²¹⁰Po and ²¹⁰Pb and residence times in key zones that include biotic (upper 60 and 300 m), sediment-water (bottom 300 m) and volcanogenic (bottom 300 m at the East Pacific Rise (EPR) station) were calculated and compared. A comparison of inventories of ²¹⁰Po and ²¹⁰Pb in 500-m layers (maximum penetration depth of atmospherically-delivered ²¹⁰Pb was reported to be upper < 500 m) for all stations indicates clearly discernable disequilibrium between total (= particulate + dissolved) ²¹⁰Po and total ²¹⁰Pb, with ²¹⁰Po/²¹⁰Pb activity ratios less than 0.95 or greater than 1.05, in 63% (26 out of 41) of the 500-m layers. The observed large variations in the ²¹⁰Po/²¹⁰Pb activity ratio (AR) in 500 m layers (range: 0.79-1.32) of the whole water column is by far the largest disequilibrium in open ocean water reported when integrated over 500 m depths. However, the whole water-column ²¹⁰Po/²¹⁰Pb AR, calculated from the inventory of total ²¹⁰Po and total ²¹⁰Pb, varied between 0.97 ± 0.02 and 1.06 ± 0.02 (except in the EPR site, with 1.09 ± 0.02), indicating at or near-equilibrium for the whole water column in all five deep water stations. This contrasts with earlier claims of gross disequilibrium between ²¹⁰Po and ²¹⁰Pb in water depths >1000 m and we contend that most of these observations do not take in to account the variable extent of redistribution of ²¹⁰Po and ²¹⁰Pb in the water column due to remineralization of biogenic particulate matter and preferential scavenging of ²¹⁰Po over ²¹⁰Pb. We observed intense scavenging of ²¹⁰Po and ²¹⁰Pb in the bottom 300 m of the EPR site (attributed to discharge of high amounts of dissolved and colloidal Fe and Mn from the hydrothermal vent) and lower scavenging in the upper and bottom 300 m at the most oligotrophic station (ST-36), indicating that the scavenging intensities in bottom waters are likely coupled to the surface waters.

210Po and 210Pb disequilibrium at the PN section in the East China Sea

Lead-210 and ²¹⁰Po have been widely used as tracers for quantifying particulate scavenging in the upper layer of the oceanic water column. In this study, we investigated the ²¹⁰Po/²¹⁰Pb disequilibrium in the water column of the PN section in the East China Sea (ECS) during autumn 2013. In most of the water column, a deficiency of ²¹⁰Po was observed with respect to its parent nuclide ²¹⁰Pb (i.e., a ²¹⁰Po/²¹⁰Pb activity ratio < 1.0). The (²¹⁰Po/²¹⁰Pb)_dissolved, (²¹⁰Po/²¹⁰Pb)_particulate and (²¹⁰Po/²¹⁰Pb)_total activity ratios ranged from 0.29 to 0.71 (average: 0.53 ± 0.13, n = 27), 0.31 to 1.42 (average: 0.70 ± 0.27, n = 27) and 0.22 to 0.62 (average: 0.50 ± 0.12, n = 27), respectively. The distribution coefficients (K_d) of ²¹⁰Po and ²¹⁰Pb were 12.1× 10⁴ ml g^-1 and 8.8× 10⁴ ml g^-1, with an average (²¹⁰Po/²¹⁰Pb) _total activity ratio of (0.50 ± 0.12, n = 27). However, over the continental shelf, planktonic detritus and fecal pellets appear to be the main carriers for ²¹⁰Po, which preferentially scavenges ²¹⁰Po and produces a lower (²¹⁰Po/²¹⁰Pb) _total activity ratio (0.49 ± 0.12, n = 22) with a K_d for ²¹⁰Po of 13.8× 10⁴ ml g^-1 in the water column. The variations in the fractionation factor (1.48 ± 0.66) of ²¹⁰Po/²¹⁰Pb reveal distinct differences between the distribution and scavenging of ²¹⁰Po and ²¹⁰Pb by particulate matter in different marine environments: in the estuarine zone (a high turbidity area), terrigenous suspended particulate matter scavenges ²¹⁰Pb from the water column, while in areas dominated by biogenic particular matter, ²¹⁰Po is preferentially scavenged from the water column. Using the ²¹⁰Po/²¹⁰Pb disequilibrium in the water column, we estimated the removal fluxes of POC from the upper waters downward to be 25.0 mg C m^-2 d^-1, comparable to those in other marginal seas. Moreover, a decreasing trend of POC removal fluxes was observed with increasing distance offshore.

Inconsistencies between 14C and short-lived radionuclides-based sediment accumulation rates: Effects of long-term remineralization

¹⁴C is the most widely utilized geochronometer to investigate geological, geochemical and geophysical problems over the past 5 decades. Establishment of precise sedimentation rates is crucial for the reconstruction of paleo-climate, -ecological and - environmental studies when extrapolation of sedimentation rates is utilized for time scales beyond the dating range. However, agreement between short-term and long-term sedimentation rates in anthropogenically unperturbed sediment cores has not been shown. Here we show that the AMS ¹⁴C-based long-term mass accumulation rate (MAR) of an organic-rich (>70%) sediment core from Mud Lake, Florida to be ∼5 times lower than the short-term MAR obtained using ^239,240Pu, ¹³⁷Cs and excess ²¹⁰Pb (²¹⁰Pb_xs). The measured sediment inventories of ²¹⁰Pb_xs, ¹³⁷Cs and ^239,240Pu are comparable to the atmospheric fallout for the sampling site, indicating very little accelerated sediment erosion over the past several decades. Presence of sharp fallout peaks of ^239,240Pu indicates very little sediment mixing. The penetration depths of ¹³⁷Cs and ^239,240Pu were found to be much deeper than expected and this is attributed to their post-depositional mobility. MAR calculated using ¹⁴C-ages in successive layers also indicated decreasing MARs with depth, and was reflective of progressive remineralization. Using first-order kinetics, the sediment remineralization rate was found to be 4.4 × 10^-4 y^-1 and propose that over the long-term, remineralization of organic-rich sediment affected the long-term MAR, but not the ratio of ¹⁴C/¹²C. Thus, the MAR and linear sedimentation rate obtained using ¹⁴C (and other isotope-based methods) could be erroneous, although ¹⁴C ages may not be affected by such remineralization. Long-term remineralization rates of organic matter has a direct bearing on the biogeochemical cycling of elements in aqueous systems and mass balance of elements needs to be taken into consideration.

A computed tomography study in the location of greater palatine artery in South Indian population for maxillary osteotomy

INTRODUCTION

The greater palatine artery is one of the important feeding vessel to the maxilla. The surgeon should know the surgical anatomy of greater palatine artery to avoid trauma in maxilla which leads to ischemic problems.

AIM

The CT evaluation of the distance between Pyriform aperture and the greater palatine foramen in various ages of both sexes.

RESULT

The distance varies according to sex and age which are measured by CT and standardised.

DISCUSSION

The lateral nasal osteotomy can be done upto 25 mm depth, instead of 20 mm.

CONCLUSION

By this study it shows that the lateral nasal wall osteotomy can be performed without injury to greater palatine artery.

Historical Associations of Molecular Measurements of Escherichia coli and Enterococci to Anthropogenic Activities and Climate Variables in Freshwater Sediment Cores

This study investigated the long-term associations of anthropogenic (sedimentary P, C, and N concentrations, and human population in the watershed), and climatic variables (air temperature, and river discharge) with Escherichia coli uidA and enterococci 23S rRNA concentrations in sediment cores from Anchor Bay (AB) in Lake St. Clair, and near the mouth of the Clinton River (CR), Michigan. Calendar year was estimated from vertical abundances of (137)Cs. The AB and CR cores spanned c.1760-2012 and c.1895-2012, respectively. There were steady state concentrations of enterococci in AB during c.1760-c.1860 and c.1910-c.2003 at ∼0.1 × 10(5) and ∼2.0 × 10(5) cell equivalents (CE) per g-dry wt, respectively. Enterococci concentrations in CR increased toward present day, and ranged from ∼0.03 × 10(5) to 9.9 × 10(5) CE/g-dry wt. The E. coli concentrations in CR and AB increased toward present day, and ranged from 0.14 × 10(7) to 1.7 × 10(7) CE/g-dry wt, and 1.8 × 10(6) to 8.5 × 10(6) CE/g-dry wt, respectively. Enterococci was associated with population and river discharge, while E. coli was associated with population, air temperature, and N and C concentrations (p < 0.05). Sediments retain records of the abundance of fecal indicator bacteria, and offer a way to evaluate responses to increased population, nutrient loading, and environmental policies.

Diurnal intraocular pressure fluctuation and its risk factors in angle-closure and open-angle glaucoma

PURPOSE

To evaluate intraocular pressure (IOP) fluctuation during office hours and its predictive factors in untreated primary angle-closure suspects (PACS); post-iridotomy primary angle closure (PAC) and primary angle-closure glaucoma (PACG) eyes with or without IOP-lowering medication(s) as appropriate and medically treated primary open-angle glaucoma (POAG) eyes.

METHODS

One-hundred seventeen eyes (29 PACS, 30 PAC, 28 PACG, and 30 POAG) of 117 patients were included in this cross-sectional study. The subjects underwent hourly IOP measurements with Goldmann tonometer from 0800 to 1700 hours. Subjects with PAC and PACG had laser peripheral iridotomy at least 2 weeks prior to the inclusion. SD of office-hour IOP readings was the main outcome measure.

RESULTS

IOP fluctuation differed between the groups (P=0.01; Kruskal-Wallis Test). Post hoc Mann-Whitney U-tests showed significantly less IOP fluctuation in PACS compared with PACG (P<0.01). Peak office-hour IOP was observed in the morning in untreated subjects and in the early afternoon in treated subjects. A stepwise linear regression model identified the presence of peripheral anterior synechiae (PAS), thickness of lens, large vertical cup-to-disc ratio (VCDR), and PAC category as significant predictive factors associated with office-hour IOP fluctuation.

CONCLUSIONS

Diurnal IOP fluctuation in asymptomatic PACSs was less than that in treated PACG subjects and was at least comparable to that in treated PAC and POAG subjects. The greater the amount of PAS, the thicker the lens, the larger the VCDR, the greater was the IOP fluctuation during office hours.

Cleft rhinoplasty

It is universally accepted that correction of cleft lip nose deformity remains a formidable challenge for any cleft surgeon. The nose is a prominent part of the face, and hence a masterly executed cleft lip repair directs the beholders' eyes from the deformed lip to the deformed nose. A deformed nose that results from unilateral cleft of the lip and palate is likened to a tent whose one side is depressed. Many investigators believe that the deformity of the nose is produced by the malpositioning of essentially normal structures, on the other hand some cleft surgeons contend that it is the intrinsic defects in nasal structures that result in cleft nasal deformity. Depressed and hypoplastic bony scaffolding is the most important aspect of cleft nose deformity and addressing this aspect of cleft nose deformity is the secret of success of a perfect secondary rhinoplasty. Controversy still exists on timing of cleft nasal deformity. Proponents of delayed nasal repair suggest that altering the cartilages in early nasal repair at the time of lip repair would complicate future corrective nasal surgeries if the primary repair would prove unsatisfactory. The correction of nasal deformity could be performed with closed or open technique. This paper highlights one such challenging unilateral cleft lip nasal deformity in a adult patient treated by secondary rhinoplasty by open technique.

A simple and non-contact optical imaging probe for evaluation of corneal diseases

Non-contact imaging techniques are preferred in ophthalmology. Corneal disease is one of the leading causes of blindness worldwide, and a possible way of detection is by analyzing the shape and optical quality of the cornea. Here, a simple and cost-effective, non-contact optical probe system is proposed and illustrated. The probe possesses high spatial resolutions and is non-dependent on coupling medium, which are significant for a clinician and patient friendly investigation. These parameters are crucial, when considering an imaging system for the objective diagnosis and management of corneal diseases. The imaging of the cornea is performed on ex vivo porcine samples and subsequently on small laboratory animals, in vivo. The clinical significance of the proposed study is validated by performing imaging of the New Zealand white rabbit's cornea infected with Pseudomonas.

Mobility of Po and U-isotopes under acid mine drainage conditions: an experimental approach with samples from Río Tinto area (SW Spain)

Under acid mine drainage (AMD) conditions, the solubilities and mobilities of many elements are vastly different from conditions prevailing in most natural waters. Studies are underway in the Río Tinto area (Iberian Pyrite Belt), in order to understand the behavior and mobility of long-lived U-series radionuclides under AMD conditions. A set of leaching experiments utilizing typical country rocks from the Tinto River basin, waste rock pile composite materials, iron-rich riverbed sediments and gossan (weathered naturally rock) were performed towards this purpose. Initial leaching experiments using distilled water kept in contact with solid material for 300, 100, 50 and 1 h resulted in very low concentrations of U with (234)U/(238)U activity ratios close to equilibrium and activity concentrations of (210)Po < 0.03 mBq/g. Leaching experiments performed with sulfuric acid media (0.1 and 0.01 M), and contact times between the solid and solution for 24 h were conducted to quantify the amount of U-isotopes and (210)Po leached, and the radioactive disequilibria generated between the radionuclides in the leachate. These experiments show that Po mobility in acidic conditions (pH around 1-2) is very low, with (210)Po activity in the leachate to be 6% in average for the solid sample. By contrast, mobility of U-isotopes is higher than that of Po, around 1.2%.

Investigations of the partitioning and residence times of Po-210 and Pb-210 in a riverine system in Southeast Michigan, USA

Some of the daughter products in the (222)Rn-decay series, such as (210)Po and (210)Pb, have been widely used as tracers and chronometers in aqueous systems. We measured the concentrations of (210)Pb and (210)Po in the dissolved (≤0.5 μm), bulk (unfiltered) and particulate phases (≥1 μm) collected in the Clinton River in the Lake St. Clair watershed in Southeast Michigan in order to investigate their partitioning between particulate and dissolved phases. Activity measurements of the dissolved and particulate phases revealed that an average of 38% (range: 12-59%) and 33% (range: 12-66%) of the total (210)Pb and (210)Po, respectively, in the water column was found in the particulate phase. The activity of dissolved and total (210)Pb was higher than that of (210)Po because of the higher atmospheric depositional fluxes of (210)Pb compared to (210)Po. Although the calculated Kd values of (210)Pb and (210)Po were similar, there was an inverse relationship between the Kd and suspended particulate matter concentration, indicating the presence of a particle concentration effect and we attribute this observation to the presence of significant amounts of colloidal (210)Po and (210)Pb in the dissolved phase. The fractionation factors for Po and Pb were found to be less than 1 in most cases. The first-order box model calculation-based residence times with respect to scavenging varied from 2 to 25 days for (210)Pb and 19-78 days for (210)Po, indicating higher particle-reactivity of (210)Pb compared to (210)Po.

Problems with the dating of sediment core using excess (210)Pb in a freshwater system impacted by large scale watershed changes

Pb-210 dating of freshwater and coastal sediments have been extensively conducted over the past 40 years for historical pollution reconstruction studies, sediment focusing, sediment accumulation and mixing rate determination. In areas where there is large scale disturbance of sediments and the watershed, the vertical profiles of excess (210)Pb ((210)Pbxs) could provide erroneous or less reliable information on sediment accumulation rates. We analyzed one sediment core from Hendrix Lake in southwestern Arkansas for excess (210)Pb and (137)Cs. There is no decrease in excess (210)Pb activity with depth while the (137)Cs profile indicates sharp peak corresponding to 1963 and the (137)Cs penetration depth of (137)Cs corresponds to 1952. The historical data on the accelerated mercury mining during 1931-1944 resulted in large-scale Hg input to this watershed. Using the peak Hg activity as a time marker, the obtained sediment accumulation rates agree well with the (137)Cs-based rates. Four independent evidences (two-marker events based on (137)Cs and two marker events based on Hg mining activity) result in about the same sedimentation rates and thus, we endorse earlier suggestion that (210)Pb profile always needs to be validated with at least one another independent method. We also present a concise discussion on what important factors that can affect the vertical profiles of (210)Pbxs in relatively smaller lakes.

Note: A gel based imaging technique of the iridocorneal angle for evaluation of angle-closure glaucoma

Noninvasive medical imaging techniques have high potential in the field of ocular imaging research. Angle closure glaucoma is a major disease causing blindness and a possible way of detection is the examination of the anterior chamber angle in eyes. Here, a simple optical method for the evaluation of angle-closure glaucoma is proposed and illustrated. The light propagation from the region associated with the iridocorneal angle to the exterior of eye is considered analytically. The design of the gel assisted probe prototype is carried out and the imaging of iridocorneal angle is performed on an eye model.

Application of (234)U/(238)U activity ratios to investigations of subterranean groundwater discharge in the Cádiz coastal area (SW Spain)

The activity ratios of (234)U/(238)U were used to investigate processes of subterranean groundwater discharge into coastal marine waters in a study location at Bay of Cádiz (southwest Spain). Marine waters in the bay and surrounding open ocean exhibited U concentrations of 3.4 ± 0.1 μg/L and activity ratios of 1.15 ± 0.01, in agreement with the expected composition of seawater ((234)U/(238)U activity ratio = 1.148 ± 0.002). Three water samples obtained from the discharge zone of the Guadalete River exhibited activity ratios of 1.17-1.22 along with slightly lower U concentrations compared to seawater, which is likely due to mixing between seawater and a groundwater end-member. One possible source of groundwater was characterized by sampling and analyzing a well water sample collected in the neighboring village of El Puerto de Santa María; this water sample exhibited an activity ratio of 1.34 ± 0.03 and a U concentration of 1.22 μg/L. Water from the Guadelete River estuarine zone can be explained to result from a two-component mixture of seawater and groundwater from the El Puerto de Santa María well; however, if there are several groundwater reservoirs with different U activity ratios that discharge to the coastal water, then, it may be difficult and more studies are being conducted to address this issue.

Radioactive impact in South Korea from the damaged nuclear reactors in Fukushima: evidence of long and short range transport

Traces of long-lived fallout-derived radioisotopes ((134)Cs and (137)Cs) were found in wet and dry deposition samples collected from the west and east coasts of South Korea from March to May 2011 following the release of radionuclides from the damaged nuclear power plants in Fukushima, Japan. The analysis of air mass back trajectory and atmospheric pressure systems indicated that the Fukushima-derived radiocaesium had predominantly reached South Korea from the west by surface westerlies from 11 March to 5 April; however, after 6 April, air masses arrived from Japan directly due to a high pressure system that developed to the east of Japan. Spatial variation of deposition fluxes of radiocaesium in South Korea was partly attributed to the presence of local longitudinal orography.

Tracking the complete revolution of Surface Westerlies over Northern Hemisphere using radionuclides emitted from Fukushima

Massive amounts of anthropogenic radionuclides were released from the nuclear reactors located in Fukushima (northeastern Japan) between 12 and 16 March 2011 following the earthquake and tsunami. Ground level air radioactivity was monitored around the globe immediately after the Fukushima accident. This global effort provided a unique opportunity to trace the surface air mass movement at different sites in the Northern Hemisphere. Based on surface air radioactivity measurements around the globe and the air mass backward trajectory analysis of the Fukushima radioactive plume at various places in the Northern Hemisphere by employing the Hybrid Single-Particle Lagrangian Integrated Trajectory model, we show for the first time, that the uninterrupted complete revolution of the mid-latitude Surface Westerlies took place in less than 21 days, with an average zonal velocity of>60 km/h. The position and circulation time scale of Surface Westerlies are of wide interest to a large number of global researchers including meteorologists, atmospheric researchers and global climate modellers.

Automatic glaucoma diagnosis from fundus image

Glaucoma is currently diagnosed by glaucoma specialists using specialized imaging devices like HRT and OCT. Fundus imaging is a modality widely used in primary healthcare. An automatic glaucoma diagnosis system based on fundus image can be deployed to primary healthcare clinics and has potential for early disease diagnosis. A mass glaucoma screening program can also be facilitated using such a system. We present an automatic fundus image based cup-to-disc ratio measurement system; and demonstrate its potential for automatic objective glaucoma diagnosis and screening. It provides strong support to use fundus image as the modality for automatic glaucoma diagnosis.

Anthropogenic and natural radionuclides in caribou and muskoxen in the western Alaskan Arctic and marine fish in the Aleutian Islands in the first half of 2000s

A number of caribou and muskoxen samples from the western Alaskan Arctic and fish samples from the Aleutian Islands were collected between 1998 and 2006 and analyzed for anthropogenic ((90)Sr and (137)Cs) and natural radionculides ((40)K, (210)Pb and (226)Ra), as part of the radiological assessment for the regional subsistence hunting communities in the first half of 2000s. We examined the relationship between the activities of these nuclides with the size of the fish. In caribou samples, concentration of (90)Sr in muscle was below the detection limit of 0.14 Bq kg(-1) and (137)Cs concentration in bones was below the detection limit of 0.15 Bq kg(-1). (137)Cs activity varied over an order of magnitude in caribou muscle samples with an average value of 2.5 Bq/kg wet wt. Average (137)Cs activity in muskoxen muscle was found to be 9.7 Bq/kg wet wt. However, there were a little variation (less than 60%) in (210)Pb, (40)K, and (226)Ra in both muscle and bone of both caribou and muskoxen. The activities of total (210)Pb in caribou and muskox bones were found to be 1-2 orders of magnitude higher than that of parent-supported (210)Pb indicating the potential for dating of bones of terrestrial mammals (time elapsed since the death of the animal) based on the excess (210)Pb method exists. In fish muscle samples, (137)Cs activity varied from below detection limit to 154 mBq/kg wet wt. and its content increased with the size of the fish due to its transfer through the food chain. Among the seven fish species investigated, (210)Pb activities varied almost an order of magnitude; however, (40)K and (226)Ra activities varied less than a factor of two. Total annual effective dose due to (90)Sr and (137)Cs from the ingestion of those terrestrial and marine meats was estimated to be negligible (ca. 9 μSV/a) compared to the natural radionuclides present thus posing negligible radiological threat to humans.

Po-210 and Pb-210 as atmospheric tracers and global atmospheric Pb-210 fallout: a review

Over the past ∼ 5 decades, the distribution of (222)Rn and its progenies (mainly (210)Pb, (210)Bi and (210)Po) have provided a wealth of information as tracers to quantify several atmospheric processes that include: i) source tracking and transport time scales of air masses; ii) the stability and vertical movement of air masses iii) removal rate constants and residence times of aerosols; iv) chemical behavior of analog species; and v) washout ratios and deposition velocities of aerosols. Most of these applications require that the sources and sink terms of these nuclides are well characterized. Utility of (210)Pb, (210)Bi and (210)Po as atmospheric tracers requires that data on the (222)Rn emanation rates is well documented. Due to low concentrations of (226)Ra in surface waters, the (222)Rn emanation rates from the continent is about two orders of magnitude higher than that of the ocean. This has led to distinctly higher (210)Pb concentrations in continental air masses compared to oceanic air masses. The highly varying concentrations of (210)Pb in air as well the depositional fluxes have yielded insight on the sources and transit times of aerosols. In an ideal enclosed air mass (closed system with respect to these nuclides), the residence times of aerosols obtained from the activity ratios of (210)Pb/(222)Rn, (210)Bi/(210)Pb, and (210)Po/(210)Pb are expected to agree with each other, but a large number of studies have indicated discordance between the residence times obtained from these three pairs. Recent results from the distribution of these nuclides in size-fractionated aerosols appear to yield consistent residence time in smaller-size aerosols, possibly suggesting that larger size aerosols are derived from resuspended dust. The residence times calculated from the (210)Pb/(222)Rn, (210)Bi/(210)Pb, and (210)Po/(210)Pb activity ratios published from 1970's are compared to those data obtained in size-fractionated aerosols in this decade and possible reasons for the discordance is discussed with some key recommendations for future studies. The existing global atmospheric inventory data of (210)Pb is re-evaluated and a 'global curve' for the depositional fluxes of (210)Pb is established. A current global budget for atmospheric (210)Po and (210)Pb is also established. The relative importance of dry fallout of (210)Po and (210)Pb at different latitudes is evaluated. The global values for the deposition velocities of aerosols using (210)Po and (210)Pb are synthesized.

The Chennai glaucoma study: prevalence and risk factors for glaucoma in cataract operated eyes in urban Chennai

We report the prevalence and risk factors for glaucoma among aphakes and pseudophakes in 3850 subjects who participated in a population-based study in urban south India. The subjects underwent an ophthalmic examination including applanation tonometry, gonioscopy, optic disc evaluation and frequency doubling perimetry. Glaucoma was diagnosed using the International Society of Geographical and Epidemiological Ophthalmology (ISGEO) criteria. Thirty eight, 15 aphakes and 23 pseudophakes (0.99% of 3850 subjects) of the 406 persons who had undergone cataract surgery were diagnosed with glaucoma. Aphakes/pseudophakes were at higher risk of glaucoma as compared to the phakic population (Odds Ratio: 2.71, 95% CI: 1. 94, 3.38, p=0.001). On multivariate analysis, older age and higher intra ocular pressure were risk factors for glaucoma. Blindness attributable to glaucoma was detected in 20% of aphakic and 4.3% of pseudophakic eyes. Glaucoma was a significant cause of morbidity in those who had undergone cataract surgery in this urban population.

Agreement between two Goldmann type applanation tonometers

The aim of the study was to assess agreement between two commercially available applanation tonometers for the measurement of intraocular pressure (IOP). Forty subjects underwent IOP measurement on two accurately calibrated Goldmann type applanation tonometers (Zeiss AT 030 (GATZ) and Inami L-5110(GATI)). The order of examination was randomized and observers were masked to the IOP recorded. The mean of two consecutive readings, from a randomly selected eye for each subject, was used for analysis. Agreement was assessed using the Altman and Bland plot. The mean (SD) IOP readings on GATZ was 15.32 (±6.80) mm Hg and on GATI was 13.52 (±5.65) mm Hg (p<0.001, 95% CI of the difference: -2.48 to -1.11). The 95% limits of agreement on the Altman and Bland plot were:-2.47 to 6.16 mm Hg). There was significant inter-instrument variability between the two accurately calibrated Goldmann type applanation tonometers studied.

Prevalence of Primary Angle-Closure Disease in an Urban South Indian Population and Comparison with a Rural Population

OBJECTIVE

To determine the prevalence of primary angle-closure glaucoma (PACG), primary angle closure (PAC), and PAC suspect (PACS) in an urban population, and to compare prevalence and associated risk factors with a rural population.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

Four thousand eight hundred subjects 40 years or older were selected from Chennai city using multistage random cluster sampling.

INTERVENTION

All subjects had a complete ophthalmic examination that included logarithm of the minimum angle of resolution visual acuity, applanation tonometry, gonioscopy, grading of lens opacities, dilated fundus examination, optic disc photography, and visual fields.

MAIN OUTCOME MEASURES

Glaucoma was diagnosed using the International Society of Geographical and Epidemiological Ophthalmology classification.

RESULTS

Three thousand eight hundred fifty (80.2%) responded; 34 subjects (17 female, 17 male) had PACG (0.88%; 95% confidence interval [CI], 0.60-1.16). The mean intraocular pressure (IOP) was 26.0+/-14.9 mmHg. Five subjects (14.7%) had been previously diagnosed to have glaucoma, 1 of whom had undergone glaucoma surgery and 2 of whom had been diagnosed to have open-angle glaucoma. Two subjects (5.9%) were bilaterally and 3 subjects (8.8%) were unilaterally blind. One hundred six subjects (2.75%; 95% CI, 2.01-3.49) were diagnosed to have PAC (62 female, 44 male). Thirty-nine subjects (36.8%) had presenting IOP > 24 mmHg, 83 (78.3%) had peripheral anterior synechiae, and 16 (15.1%) had both. Two hundred seventy-eight subjects (7.24%; 95% CI, 6.38-8.02) had PACS (183 female, 95 male). Prevalences of PACG and PACS were similar in the urban and rural populations. Primary angle closure prevalence was higher in the urban population (P<0.0001). Primary angle closure and PACG were positively associated with increasing age and IOP in both populations and were more common in rural women (odds ratio [OR], 4.3; 95% CI, 2.2-8.3). Association with hyperopia was seen only in the urban population (OR, 2.0; 95% CI, 1.4-2.8).

CONCLUSIONS

Prevalences of PACG and PACS were similar in the rural and urban populations; PAC was more common in the urban population. In both groups, the disease was asymptomatic. Poor detection rates were probably due to lack of gonioscopy as a routine part of an eye examination.

Prevalence of Primary Open-angle Glaucoma in an Urban South Indian Population and Comparison with a Rural Population

OBJECTIVE

To estimate the prevalence and risk factors of primary open-angle glaucoma (POAG) in an urban population and compare the same with that of our published rural population data in southern India.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

Four thousand eight hundred subjects 40 years or older were selected using a multistage random cluster sampling procedure in Chennai city.

INTERVENTION

Three thousand eight hundred fifty (80.2%) subjects underwent a complete ophthalmic examination, including applanation tonometry, gonioscopy, pachymetry, optic disc photography, and automated perimetry.

MAIN OUTCOME MEASURES

Glaucoma was diagnosed using the International Society of Geographical and Epidemiological Ophthalmology Classification.

RESULTS

The distribution of intraocular pressure (IOP) and vertical cup-to-disc ratio (VCDR) was obtained from the right eye of the 2532 subjects with normal suprathreshold visual fields. Mean IOP was 16.17+/-3.74 mmHg (97.5th and 99.5th percentiles, 24 mmHg and 30 mmHg). The mean VCDR was 0.43+/-0.17 (97.5th and 99.5th percentiles, 0.7 and 0.8). One hundred thirty-five (64 men, 71 women) subjects had POAG (3.51%; 95% confidence interval [CI], 3.04-4.0). Primary open-angle glaucoma subjects (58.4+/-11.3 years) were older (P<0.0001) than the study population (54.8+/-10.6 years). One hundred twenty-seven (94%) subjects were diagnosed to have POAG for the first time. Two subjects (1.5%) were bilaterally blind, and 3 (3.3%) were unilaterally blind due to POAG. The urban population prevalence was more than that of the rural population (1.62%; 95% CI, 1.4%-1.8%; P<0.0001). In both populations, increasing IOP (per millimeter of mercury) and older age were associated with the disease. There was no association with gender, myopia, systemic hypertension, diabetes, or central corneal thickness.

CONCLUSIONS

The prevalence of POAG in a > or =40-year-old south Indian urban population was 3.51%, higher than that of the rural population. The prevalence increased with age, and >90% were not aware of the disease.

A randomized, crossover, open label pilot study to evaluate the efficacy and safety of Xalatan ® in comparison with generic Latanoprost (Latoprost) in subjects with primary open angle glaucoma or ocular hypertension

AIM

To compare the efficacy and tolerability of Xalatan with generic latanoprost (Latoprost) in subjects with primary open angle glaucoma (POAG) or ocular hypertension (OH).

MATERIALS AND METHODS

This was a single-center, randomized, open label, crossover, two period comparative study. At the baseline visit, subjects were randomized to two groups. Group A received Xalatan for weeks 1-12 followed by Latoprost for weeks 13-24. Group B received Latoprost for weeks 1-12 followed by Xalatan for weeks 13-24.

RESULTS

30 subjects were recruited, 12 in Group A and 18 in Group B. In subjects administered Xalatan, intraocular pressure (IOP) showed a greater decrease (P < 0.001) from 23.64 +/- 3.13 mmHg at baseline to 14.29 +/- 1.61 mmHg at week 12 (fall of 9.35 +/- 3.55 mmHg, 38.66% +/- 10.29) than that seen in the Latoprost group (22.74 +/- 2.47 mmHg to 16.98 +/- 2.49 mmHg, fall of 5.76 +/- 1.41 mmHg; 25.42% +/- 5.98). In period 2 when subjects were crossed over to Xalatan from Latoprost, there was a further fall from 16.98 +/- 2.49 mmHg to 16.09 +/- 1.49 at week 24 (fall of 0.89 +/- 1.59 mmHg; 4.3% +/- 8.76). However, when subjects were crossed over to Latoprost from Xalatan, the IOP rose from 14.29 +/- 1.61 mmHg to 15.36 +/- 1.71 mmHg at week 24 (8.86% +/- 17.76). There was no significant difference in incidence of conjunctival hyperemia or any other adverse events in both the groups.

CONCLUSION

The magnitude of IOP lowering in patients with POAG and OH with Xalatan and Latoprost is different. In our study, the IOP lowering with Xalatan was higher than that with Latoprost.

Central corneal thickness and its relationship to myopia in Chinese adults

AIM

To investigate the association between central corneal thickness (CCT) and the degree of myopia among Chinese.

METHODS

In this prospective observational study, 714 consecutive patients were recruited from a refractive surgery clinic. CCT was measured in both eyes of each patient using the Orbscan (Bausch and Lomb, Rochester, New York, USA), and data of the right eye were selected for analysis. CCT was correlated with the degree of myopia in dioptres (D) using Pearson's correlation coefficient and Dunnett's t test with multiple comparisons.

RESULTS

The age of the patients ranged from 15 to 59 years. The mean CCT was 534.5 microm, with a standard deviation (SD) of 38.1 (range 305-684) microm. The mean (SD) myopic spherical equivalent was 5.30 (2.74) D, range -17.5--0.625 D. No correlation was found between CCT and the degree of myopia (r = -0.13, p = 0.719).

CONCLUSIONS

Among Chinese with myopia, CCT was distributed over a large range but did not correlate with the degree of myopia.

OPTN gene: profile of patients with glaucoma from India

PURPOSE

Optineurin gene (OPTN) mutations are reported in primary open angle glaucoma patients (POAG) from different populations. The coding and noncoding regions of OPTN were screened for mutations in 100 Indian high tension glaucoma patients (HTG). The frequency of the OPTN M98K mutation in an additional 120 patients (70 HTG and 50 normal tension glaucoma [NTG]) was analyzed by restriction enzyme digestion.

METHODS

The HTG patients (about 40 years of age) were characterized by open angles on gonioscopy, with raised intraocular pressure (IOP) more than 21 mmHg (<21 mmHg on office diurnal phasing for NTG), and typical glaucomatous disc changes with corresponding visual field defects in the absence of any secondary cause. One hundred HTG patients and controls were screened for OPTN mutations by direct sequencing using an ABI prism 310/3100 Avant genetic analyzer. The M98K status was analyzed by restriction enzyme digestion with StuI. A genotype/phenotype correlation was also attempted for OPTN sequence alterations with clinical parameters such as age at diagnosis, intraocular pressure, cup:disc ratio, etc. The putative change in the transcription factor binding site for the IVS7 +24G>A polymorphism was attempted with AliBaba software (version 2.1).

RESULTS

Six sequence alterations were observed in the 100 POAG patients by direct sequencing. The M98K substitution was observed in a total of 10 patients (7/170 HTG and 3/50 NTG) contributing to 4.1% in HTG and 6% in the NTG group and not in the controls. The IVS7+24G>A nucleotide change showed a significant difference in the HTG group (7/100) when compared to the control group (0/100) and found to be associated with increased IOP at diagnosis (p=0.03). The IVS7+24G>A polymorphism resulted in the creation of binding sites for transcription factors NF-1 and CPE that were not present in the wild type.

CONCLUSIONS

The current study suggests a possible role of SNPs rather than mutations in OPTN in POAG pathology in the Indian population.

Influence of tobacco use on cataract development

AIM

To study the influence of tobacco use on cataract formation in a rural South Indian population.

METHODS

3924 subjects from the Chennai Glaucoma Study conducted in rural south India underwent a comprehensive eye examination, including Lens Opacities Classification System II grading. Information on tobacco use, type of tobacco (smoking and smokeless), duration and quantity of use was collected.

RESULTS

1705 (male:female (M:F) 1106:599) people used tobacco and were significantly older (mean (standard deviation (SD)) age 55.80 (10.64) years) than non-users (52.23 (10.51); p<0.001). 731 (M:F 730:1) people smoked, 900 (M:F 302:598) used smokeless tobacco, and 74 (M:F, 74:0) used tobacco in both forms. The unadjusted and adjusted (age and sex) odds ratio (OR) for a positive history of tobacco use and cataract was 1.72 (95% confidence interval (CI) 1.51 to 1.96) and 1.39 (95% CI 1.15 to 1.68), respectively. The unadjusted OR for smokers and smokeless tobacco users was 1.04 (95% CI 0.88 to 1.23) and 2.74 (95% CI 2.31 to 3.26), respectively. The adjusted OR was 1.19 (95% CI 0.89 to 1.59) and 1.54 (95% CI 1.22 to 1.95), respectively. No significant association was noted between smoking and any particular type of cataract. Smokeless tobacco use was found to be significantly associated with nuclear cataract even after adjusting for age and sex (OR 1.67, p = 0.067, 95% CI 1.16 to 2.39).

CONCLUSION

Tobacco use was significantly associated with cataract. Smoking was not found to be significantly associated with cataract formation; however, smokeless tobacco use was more strongly associated with cataract.

Comparison of pulsatile ocular blood flow in Indians and Europeans

PURPOSE

To compare pulsatile ocular blood flow (POBF) in Europeans and Indians and provide reference values for a group of healthy Indians.

PATIENTS AND METHODS

Measurement with the POBF Tonograph was performed on healthy Indian subjects in India (n=252). A further 80 subjects (40 of Indian descent and 40 Europeans) underwent measurements in Cambridge, England. The instrument used for measurement was the same for both the studies.

RESULTS

The mean POBF in the Indians in India was found to be 1176 microl/min. The mean POBF value in the Europeans was found to be 1033 microl/min and that for Indians in England was 1061 microl/min. The difference between the POBF within groups was significant (one-way ANOVA P<0.05) with the POBF of Indians in India being higher than Europeans and Indians in the UK. The difference between the Europeans and Indians in the UK did not reach statistical significance.

CONCLUSIONS

POBF values in Indians living in India were found to be considerably higher than the previously published normal value of 650 microl/min in European studies and other studies for other racial groups. The reason for this apparent difference may be instrument-related rather than genetic because such a large difference was not observed when a comparison was performed in the UK. In addition, the results for both groups in our comparative study were still considerably higher than reported in previous studies. The POBF of Indians in India is slightly higher than the POBF of people of Indian ethnic origin in England.

Prevalence and causes of blindness in the rural population of the Chennai Glaucoma Study

AIM

To study the prevalence and causes of blindness in a rural south Indian population.

METHODS

3924/4800 enumerated (81.75%) subjects, aged 40 years or more from rural Tamil Nadu, underwent comprehensive ophthalmic examination-visual acuity, refraction, intraocular pressure, gonioscopy, cataract grading (LOCS II), retinal examination, and SITA Standard where indicated. Blindness was defined using WHO criteria as best corrected visual acuity of less than 3/60 and/or visual field of less than 10 degrees in the better eye. The influence of age, sex, literacy, and occupation was assessed using multiple logistic regression.

RESULTS

753 subjects (19.2%; 321 males, 432 females) presented with a visual acuity of <3/60; 132 subjects (3.36%, 95% CI: 2.80 to 3.93) were diagnosed to be blind. Cataract was responsible in 74.62% of eyes; glaucoma, cystoid macular oedema, optic atrophy, and corneal scars accounted for 3.79% each. Bilateral causes of blindness were cataract (78.63%), glaucoma (4.29%), optic atrophy (3.42%), cystoid macular oedema, and corneal scars (2.56% each). In 19 eyes (7.2%) the blindness was probably related to cataract surgery. Blindness was positively associated with increasing age (p<0.0001).

CONCLUSION

3.36% of the studied rural population was bilaterally blind, with cataract being the single most important cause.

Prevalence of Angle-Closure Disease in a Rural Southern Indian Population

OBJECTIVE

To estimate the prevalence of primary angle-closure glaucoma, primary angle closure (PAC), and primary angle-closure suspect (PACS) and its associated risk factors in a rural population in southern India.

METHODS

Three thousand and nine hundred thirty-four (81.95%) of 4800 enumerated subjects aged 40 years or older underwent a complete ophthalmic examination, including compression gonioscopy. Glaucoma was diagnosed using International Society of Geographical and Epidemiological Ophthalmology classification.

RESULTS

Data were analyzed for 3924 subjects (81.75%). Primary angle-closure glaucoma was diagnosed in 34 subjects (0.87%; 95% confidence interval [CI], 0.58 to 1.16) (27 women, 7 men). The mean intraocular pressure was 20.71 +/- 9.24 mm Hg. One subject (2.94%) was blind. Twenty-eight subjects (0.71%; 95% CI, 0.45 to 0.98) were diagnosed to have PAC (21 women, 7 men). Eleven subjects (39.3%) had an intraocular pressure greater than 21 mm Hg, 13 subjects (46.43%) had peripheral anterior synechiae, and 4 subjects (14.29%) had both. Two hundred forty-six subjects (6.27%; 95% CI, 5.51 to 7.03) had PACS (168 women, 78 men). Primary angle closure and primary angle-closure glaucoma were more common in women (age-adjusted odds ratio, 3.02; 95% CI, 1.66 to 5.51) with an increasing prevalence with age. Increasing intraocular pressure was associated with the disease (odds ratio, 1.14; 95% CI, 1.09 to 1.19). There was no association with hypertension and hyperopia. Axial length and anterior chamber depth were longer in the normal group than in the 3 groups with angle closure (P<.05). Women had shorter axial lengths than men (P<.001) in the angle closure groups.

CONCLUSIONS

The overall prevalence of primary angle closures (PAC and primary angle-closure glaucoma) in a rural population of southern India was 1.58%. There was a female preponderance, and the disease tends to be asymptomatic.

Frosted cylindrical lens induced artefact on Humphrey automated perimetry

BACKGROUND

The aim of this study was to assess the effect of a cylindrical corrective lens with frosted sides on Humphrey automated perimetry performed with a translucent spectacle occluder in the contralateral eye.

METHODS

Ten healthy volunteers with cylindrical refractive errors of more than 1.50 DC had Humphrey visual fields (30-2) measured with the contralateral eye occluded with either a translucent spectacle occluder or an opaque patch. The order of testing with each occluder was randomised. Additionally, visual field examination with the opaque patch was performed on three volunteer subjects with deep-set eyes to establish the clinical significance of the frosted cylindrical lens induced artefact (CLA). The back vertex distances for the correcting lenses were measured for all tests.

RESULTS

Eight out of 10 volunteers tested with the translucent occluder demonstrated CLA, which was absent when the opaque patch was used. The presence of an artefact corresponding to the axis of the cylinder was observed, when the vertex distance was more than 15 mm. Three subjects with deep-set eyes presented with CLA, even with the use of an opaque patch.

DISCUSSION

Cylindrical lens artefacts can occur with increasing vertex distance when using a translucent spectacle occluder instead of an opaque patch. CLA is also seen in subjects with deep-set eyes.

Glaucoma in aphakia and pseudophakia in the Chennai Glaucoma Study

AIM

To determine the prevalence of glaucoma among aphakes and pseudophakes in a rural population of southern India.

METHODS

3924 subjects aged 40 years or above underwent complete ophthalmic examination. Glaucoma in aphakia/pseudophakia was diagnosed using International Society of Geographical and Epidemiological Ophthalmology criteria in aphakic/pseudophakic people.

RESULTS

54 subjects (37 aphakes, 17 pseudophakes) (1.38% of 3924 subjects, 11.2% of 482 aphakes/pseudophakes) had glaucoma in aphakia/pseudophakia. Aphakia, age, intraocular pressure (IOP), pseudoexfoliation, and peripheral anterior synechiae greater than or equal to 180 degrees of the angle were risk factors for glaucoma on univariate analysis. On multivariate analysis, IOP and aphakia were independent risk factors for glaucoma. 39 people (72.22%) with glaucoma had normal IOP at presentation. None of the people with glaucoma were aware of the disease. Blindness in one or both eyes was seen in 12 subjects (10 unilateral and two bilateral)-that is, 22.22% of people with glaucoma in aphakia/pseudophakia.

CONCLUSIONS

Glaucoma is an important cause of ocular morbidity among aphakes and pseudophakes in this rural population of south India. This glaucoma, responsible for unilateral or bilateral blindness in 22.2% of those affected, was entirely undetected in this study population.

Efficacy and safety of latanoprost for glaucoma treatment: a three-month multicentric study in India

PURPOSE

To evaluate the short-term efficacy and safety of 0.005% topical latanoprost in Indian eyes.

DESIGN

Prospective non-randomised open-label multicentric trial.

METHODS

One hundred and fifty patients with ocular hypertension (OHT), primary open-angle, pseudoexfoliation or pigmentary glaucoma were enrolled at four centers. Each center contributed at least 20 patients. Following baseline measurements, 0.005% latanoprost was applied topically once daily in the evening for three months. Patients were examined at 2, 6 and 12 weeks. The primary outcome measure was mean intraocular pressure (IOP) reduction. The mean diurnal variation of IOP (difference between highest and lowest IOP) at baseline and at 12-weeks was compared.

RESULTS

One hundred and thirty of 150 enrolled patients completed the study. One randomly selected eye of each patient was included for analysis. At three months, latanoprost reduced the mean IOP from 24.9 (+/- 3.16) mmHg at baseline to 16.10 (+/- 2.7) mmHg, a reduction of 35.25%. 83% had a reduction in IOP of > 25%. The IOP reduction was maintained throughout the study period, and was not affected by gender or age of the patient. One eye did not show any response to the drug. Daytime diurnal variation of IOP was reduced from 4.5 to 2.9 mmHg. 20 patients had conjunctival hyperemia. Six patients had side effects requiring withdrawal from the study.

CONCLUSIONS

In this short-term multicentric study, latanoprost effectively reduced IOP and stabilised the diurnal curve in Indian eyes. There were no clinically significant ocular or systemic adverse effects.

Effect of cataract surgery with intraocular lens implant on frequency doubling perimetry

PURPOSE

To study the effect of cataract surgery with intraocular lens (IOL) on frequency doubling perimetry (FDP).

METHODS

Patients aged 40 years or above seen at our outpatient clinic with no ocular pathology except for visually significant cataract and visual acuity 6/24 or better were eligible. They underwent FDP before and 4 to 6 weeks after cataract surgery with IOL.

RESULTS

Screening test: Mean scores by three different scoring methods were 1.82 (3.21), 2.80 (5.54), 4.18 (9.18) before and 0.22 (0.51), 0.26 (0.63), 0.26 (0.69) after surgery (p = 0.002 0.001, < 0.0001). Threshold test: Mean deviation (MD) and pattern standard deviation (PSD) were -5.23 (3.08) and 5.15 (2.78) before and -2.94 [corrected] (2.49) (p < 0.0001) and 5.21 (1.780) (p = 0.63) after surgery.

CONCLUSIONS

The screening test should be interpreted cautiously in the presence of cataract. On threshold testing, cataract surgery causes significant decrease in MD but no change in PSD.