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.

Does knowledge and attitude of healthcare professionals working in critical care areas affect their willingness to offer the option of organ donation? results of a tertiary hospital survey.

INTRODUCTION: Organ donation (OD) rates in Malaysia have remained suboptimal for decades. Healthcare professionals (HCPs) working in critical care areas are responsible for diagnosing brain death (BD) and initiating the OD process. Impact of their knowledge and attitudes on willingness to offer the option of OD to families of potential donors is unknown. METHODS: Knowledge and attitudes about BD, OD, and organ transplantation (OT) of critical care HCPs in a Malaysian transplant centre were studied using a validated questionnaire. Responses were analysed using multivariable analysis with willingness to offer the option of OD to families of potential donors as dependent variable. RESULTS: Age (p = 0.04), profession (doctors > nurses, p < 0.001), religion (Buddhists > others, p = 0.013) [but not ethnicity], higher knowledge scores for Brain Death Test, Brain Death Knowledge, Organ Donation and Transplantation, and overall knowledge score (p < 0.001) were associated with greater odds of offering OD to families. Belief in the reliable diagnosis of BD, confidence in explaining BD, and belief that OD will not affect religious services were significantly associated with willingness to offer OD, while HCPs who were willing to personally donate organs had greatest odds (p < 0.001). Other factors that significantly influenced HCPs' willingness to offer included their perception about families' willingness to donate, body disfigurement, and confidence in OT. CONCLUSIONS: Overall, HCPs had highly positive attitudes. However, potential barriers in offering OD to families were identified. Proven interventions from international experience could help address these issues and likely improve OD rates in Malaysia.

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 (PM0.39- 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.

Clinical Evaluation of Placement of Implant by Flapless Technique Over Conventional Flap Technique.

AIM: The aim of this study was to compare the clinical advantages of flapless implant surgery over conventional flap technique of implant placement by assessing the marginal bone loss in 1 month, 2 months and 3 months postoperatively, pain assessment, number of analgesics taken by the patients postoperatively and the postoperative swelling between two groups. MATERIALS AND METHODS: This study was conducted at Department of Oral and Maxillofacial Surgery, Rajas Dental College and Hospital, Tirunelveli. The patients were assigned randomly to one of the two groups-flap (ten patients) or flapless (ten patients). Digital IOPARs were taken postoperatively. The parameters assessed were marginal bone loss (interproximal bone height), pain assessment by a 10-cm visual analog scale, swelling assessment by modification of tape measuring method by Gabka and Matsumara and the number of analgesics tablets taken every postoperative day from the day of surgery to 6 days after surgery. RESULTS AND STATISTICS: Descriptive statistics was done by calculating measures of central tendency (mean) and measures of dispersion (standard deviation) for all the parameters. Inferential statistics were done by unpaired Student's t test to compare the mean difference between the two groups. The results of this study showed that the mean difference in the bone loss for baseline to the third month for the flap group was 0.34 ± 0.05 and for the flapless group was 0.03 ± 0.004 (p = 0.000***). Pain assessment by visual analog scale was statistically significant in all the 5 postoperative days indicating a better patient compliance in the flapless group and there was no statistical difference in the level of swelling between these two groups. CONCLUSION: Within the limitations of this study, it can be concluded that flapless implant surgery results in lesser loss of marginal bone and also results in better patient comfort; however, proper patient selection and technique is essential for a successful flapless implant surgery.

Treatment of Micrognathia by Intraoral Distraction Osteogenesis: A Prospective Study.

PURPOSE: Maxillofacial deformities are always psychologically and physically distressing to the patients and is also challenging to the treating surgeons. The term Micrognathia means a "small jaw". True micrognathia, where the maxilla or the mandibular skeleton does not grow to the full size can be congenital or acquired. Distraction osteogenesis also called as callus distraction or callostasis or osteodistraction or distraction histogenesis is a biological process of regenerating newly formed bone and adjacent soft tissue by a gradual and controlled traction of surgically separated bone segments. The purpose of this prospective study was to assess the versatility of distraction osteogenesis in the treatment of micrognathia. MATERIALS AND METHODS: Four patients (three males and one female) with micrognathia of mandible were included in this prospective study. The patients were between the age group of 10-20 years. Facial asymmetry was the chief complaint of all the patients. In all the patients following treatment protocol was carried out, Osteotomy and placement of intraoral distraction device under general anaesthesia, latency phase (5-7 days), activation period-rate 1.5 mm per day, consolidation period of 8 weeks, removal of distraction device under local anaesthesia. The parameters assessed were ramus height, body length, hyo mental distance, posterior pharyngeal airway space, chin projection, facial symmetry occlusion, mid line shift pre and post operatively. RESULTS: The mean increase in ramus height achieved was 9.2 + 2.17 mm and the mandibular body length achieved was 10.4+1.67 mm. There was an average increase in hyo-mental distance of 2.75 cm +0.9 cm postoperatively showing a definitive improvement in the airway. The posterior pharyngeal space measured from the lateral cephalogram preoperatively ranged from 3-6 mm and post operatively from 6-9 mm.Intraorally there was a shift in occlusion to class I molar relation in three patients and there was posterior open bite in one patient. Marked correction of facial asymmetry was noticed in all cases both clinically and in PA cephalogram. There was a restoration of dental as well as lip midline and improved lip competence. There was a significant improvement in chin projection and occlusal cant however further chin correction was needed in one case by means of advancement genioplasty. CONCLUSION: A definite improvement in all parameters such as body length,ramus height,chin projection,occlusal cant was observed in all patients. Moreover the patients were subjectively satisfied with the outcome of the results. Distraction Osteogenesis is definitely a boon to the oral and maxillofacial surgeons in treating large deficiencies of mandible in terms of stability.

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 (210Pbxs). The measured sediment inventories of 210Pbxs, 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.

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.

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.

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.

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.

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%.

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.

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.

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.

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.

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.