Surface Manifestations Research Articles

Existence of High Temperature Geothermal Resources in the Igneous Rock Regions of South China

Large areas of Yanshan period granites with high heat production values (3–10 μW/m3) and mantle plume around Hainan province co-exist in Igneous Rocks Regions of South China (IRRSC). Surface manifestations are mainly warm/hot springs with temperatures below 90 °C and no typical phenomenon of high temperature resources have been observed. The main objective of this paper is to discuss the existence of high temperature geothermal resources and their possible locations under this kind of geothermal and tectonic background by analysis of high temperature heat sources, borehole temperature measurement, and reservoir temperature estimation. Two possible partial melts of the magma chamber were detected as high temperature heat sources in the Southern Leizhou Peninsular and North Hainan Island at a depth of 8–15 km. Other low resistivity zones in the upper crust are more likely caused by fluid in the formations or faults but not high temperature heat sources. This was also verified by borehole temperature measurement in these two areas, with maximum formation temperatures of 211°C and 185°C found, respectively. Reservoir temperatures from fluid geothermometers show lower temperatures of between 110–160°C for typical geothermal fields over the IRRSC but not in the Southern Leizhou Peninsular and Northern Hainan Island. In all, high temperature geothermal resources may be found in the Southern Leizhou Peninsular and on Northern Hainan Island.

Common ocular findings in patients with acne rosacea

To evaluate ocular surface manifestations in patients with acne rosecea (AR) and to find out main features indicating a propensity toward an association with disease diagnosis. Right eyes of consecutive 76 AR patients and 113 age-gender matched healthy subjects were enrolled. Ophthalmologic examinations including tear break-up time (t-BUT) and Schirmer-2 tests to analyze tear film insufficiency, optical coherence tomography (OCT)-assisted infrared meibography to analyze meibomian gland drop-out, and Ocular Surface Disease Index (OSDI) questionnaire were performed in all participants. No statistically differences were found in visual acuity, intraocular pressure, central corneal thickness, and axial length assessments between the study and control eyes. Study eyes had more foreign body sensation, itching, dryness, hyperemia, conjunctival telangiectasia, and meibomitis (p ≤ 0.005, for all). Significantly higher t-BUT and Schirmer-2 tests; lower-eyelid and total OCT meibography; and OSDI scores were found in AR patients (p < 0.05, for all). Among all, only conjunctival telangiectasia (p = 0.001; OR:0.070, 95% CI:0.015-0.330) was found to be major independent predictor for AR diagnosis. Detailed slit-lamp examination to detect any conjunctival telangiectasia seems to be crucial in recalcitrant dry eye cases, not to miss underlying AR. Especially, lower-eyelid OCT meibography score may be sensitively used for disease staging.

Internal Waves as a Source of Concentric Rings within Small River Plumes

This study is focused on concentric rings, which are regularly observed by remote sensing of small river plumes located in different regions worldwide. We report new aerial observations of these features obtained by quadcopters and supported by synchronous in situ measurements, which were collected during the recent field survey at the Bzyb river plume in the eastern part of the Black Sea. Joint analysis of remote sensing imagery and in situ data suggest that the observed concentric rings are surface manifestations of high-frequency internal waves generated in the vicinity of the river mouth. The obtained results demonstrate that the propagation of these waves does not induce offshore material transport within the plume induced by shear instability, which was hypothesized in a recent numerical modeling study of this process. We provide an explanation for the appearance of misleading material features in the numerical simulations discussed above. Finally, we discuss directions for future research of high-frequency internal waves generated in small river plumes.

SARS-CoV-2 in Conjunctiva and Tears and Ocular Symptoms of Patients with COVID-19.

This study investigates the presence of SARS-CoV-2 in conjunctival secretions and tears and evaluates ocular symptoms in a group of patients with COVID-19. We included 56 hospitalized patients with COVID-19 in this cross-sectional cohort study. Conjunctival secretions and tears were collected using flocked swabs and Schirmer strips for SARS-CoV-2 reverse-transcriptase polymerase chain reaction (RT-PCR). Assessment of ocular surface manifestations included an OSDI (Ocular Surface Disease Index) questionnaire. Patients had been admitted to hospital for an average of 2.4 days (range 0–7) and had shown general symptoms for an average of 7.1 days (range 1–20) prior to ocular testing. Four (7.1%) of 56 conjunctival swabs and four (4%) of 112 Schirmer strips were positive for SARS-CoV-2. The mean E-gene cycle threshold values (Ct values) were 31.2 (SD 5.0) in conjunctival swabs and 32.9 (SD 2.7) in left eye Schirmer strips. Overall, 17 (30%) patients presented ocular symptoms. No association was found between positive ocular samples and ocular symptoms. This study shows that SARS-CoV-2 can be detected on the conjunctiva and tears of patients with COVID-19. Contact with the ocular surface may transmit the virus and preventive measures should be taken in this direction.

The effects of alteration degree, moisture and temperature on laser return intensity for mapping geothermal manifestations

Understanding alteration processes in geothermal systems through remote sensing can help assess the prospectivity of a geothermal field. As a result of which, alteration detection and mapping are vital in the early exploration stage. However, many geothermal surface manifestations, which are evidence of alteration processes, often occur in densely vegetated areas, particularly in tropical regions. Current lithological mapping techniques using passive remote sensing systems can have problems with vegetation canopy completely blocking the signal. LiDAR, an active remote sensing system, can be a solution since it can (partially) penetrate vegetation canopy. It collects information from the ground in 3D-coordinated points with laser return intensity (LRI) values. In this study, we test for the first time the possibility of differentiating hydrothermally altered rocks through their LRI values in a laboratory experiment. We scanned selected altered and unaltered rocks under different moisture and temperature conditions using a terrestrial laser scanner (at 1550 nm wavelength). Our results show LRI values follow the degree of alteration: strongly altered rocks have the highest LRI, unaltered rocks are at the lowest, and weakly altered rocks show an intermediate response. Varying moisture conditions decrease LRI values for all rocks, but the relative LRI order due to alteration remains intact. We recorded no significant temperature effect on LRI values for any of the alteration stages. Our results provide the first evidence that rocks with different hydrothermal alteration phases can be distinguished by their LRI values which opens up the potential for airborne mapping of geothermal surface manifestations with LRI.

Mantle convection and possible mantle plumes beneath Antarctica – insights from geodynamic models and implications for topography

Abstract This chapter describes large-scale mantle flow structures beneath Antarctica as derived from global seismic tomography models of the present-day state. In combination with plate reconstructions, the time-dependent pattern of palaeosubduction can be simulated and is shown from the rarely seen Antarctic perspective. Furthermore, a dynamic topography model demonstrates which kind and scales of surface manifestations can be expected as a direct and observable result of mantle convection. The last section of this chapter features an overview of the classical concept of deep-mantle plumes from a geodynamic point of view and how recent insights, mostly from seismic tomography, have changed the understanding of plume structures and dynamics over past decades. The long-standing and controversial hypothesis of a mantle plume beneath West Antarctica is summarized and addressed with geodynamic models, which estimate the excess heat flow of a potential plume at the bedrock surface. However, the predicted heat flow is small, while differences in surface heat-flux estimates are large; therefore, the results are not conclusive with regard to the existence of a West Antarctic mantle plume. Finally, it is shown that global mantle flow would cause the tilting of whole-mantle plume conduits beneath West Antarctica such that their base is predicted to be displaced about 20° northward relative to the surface position, closer to the southern margin of the Pacific Large Low-Shear Velocity Province.

Surface manifestation of stochastically excited internal gravity waves

ABSTRACT Recent photometric observations of massive stars show ubiquitous low-frequency ‘red noise’ variability, which has been interpreted as internal gravity waves (IGWs). Simulations of IGWs generated by convection show smooth surface wave spectra, qualitatively matching the observed red noise. Theoretical calculations using linear wave theory by Shiode et al. and Lecoanet et al. predict IGWs should manifest at the surface as regularly spaced peaks associated with standing g modes. In light of the apparent discrepancy between these theories and simulations/observations, we test the theories with simplified 2D numerical simulations of wave generation by convection. The simulations agree with the transfer function calculations presented in Lecoanet et al., demonstrating that the transfer function correctly models linear wave propagation. However, there are differences between our simulations and the g-mode amplitude predictions of Shiode et al. This is because that work did not take into account the finite width of the g-mode peaks; after correcting for this finite width, we again find good agreement between theory and simulations. This paper verifies the theoretical approach of Lecoanet et al. and strengthens their conclusion that IGWs generated by core convection do not have a surface manifestation consistent with observed low-frequency variability of massive stars.

Thermal zone identification by gravity data modeling using Euler deconvolution and geochemical analysis of hot springs in Saurashtra and Cambay Basins

Objective: This study is aimed at interpreting geochemical and geophysical data of 4 locations in Gujarat, India to understand the subsurface geothermal hotspot locations. Methods: CG-5 gravimeter was used to collect the gravity data. Data corrections were done to obtain a complete Bouguer anomaly. The depth of the dense bodies was calculated using Euler deconvolution. Also, the geochemical classification of physiochemical properties of geothermal spring waters of the locations was evaluated to assess their possible applications. Findings: In the sample region, the complete Bouguer anomaly analysis ranges between 1.99 mGal-2.23 mGal. The Euler deconvolution produced depth solutions ranging from 100 to 450 meters, which were mostly found near gravity highs, and the presence of deep structures can be deduced. These deep structures are translated as dense intruding bodies trapped by an overlying cap rock. The Geochemical analysis was done of the four samples. Based on the results of various plots such as Ternary, Durov, Piper, Stiff, the waters are graded as cationic with Na+K and anionic with Cl+SO4. The sample waters indicate suitability for drinking and irrigation at some locations. Finding these hotspots and exploiting them is of importance for these areas which are dealing with the acute water crisis. Novelty: Euler deconvolution of gravity data was first time applied for subtle geothermal trap identification in Saurashtra and Cambay basins. It has been established through this study that surface manifestation of these subtle traps are the hot springs. Systematic geochemical characterization of the hot springs progressed the nascent geothermal energy research of India. Keywords: Bouguer anomaly; Heat source; Geothermal energy; Geochemical analysis; Hot spring; water analysis

Investigation of Dam Integrity from Electrical Resistivity Methods: A Case of Erelu Dam, Southwestern Nigeria

DOI:10.17014/ijog.8.2.265-274Erelu dam is geologically within the Precambrian Basement Complex of southwestern Nigeria, which serves a principal source of water supply to an increasing population; currently at about 779,318. In an attempt to investigate the integrity of the dam, horizontal resistivity profiling (HRP) of dipole-dipole and Schlumberger’s vertical electrical sounding (VES) approaches were explored to delineate the lithologic layers, facies, and geologic structures in the subsurface of the dam. The HRP revealed changes in subsurface conductivity that depicts lateritic hard pan and saturated rock blankets at shallow depth. The vertical geo-electric section delineated predominant four lithologic units. The regolith is 7 m thick and constitutes the vertical rock fill impervious cores of the dam, which is underlained by saprolitic and fresh bedrock. The region of weathered rock depression coincided the shallow saturated anomalous zone and showed surface manifestation of fractured or unconsolidated terrain within the embankment. The fracture serves as conduit for seepage which could be responsible for possible loss in the reservoir water and increases its susceptibility to failure. It is recommended to keep monitoring the seepage with reservoir levels, by periodical geophysical and geotechnical measurements for the two (dry and wet) seasons.

Cyclic and monotonic simple shear testing of native Christchurch silty soil

The first cyclic simple shear tests on high-quality retrieved specimens of Christchurch silty and sandy soil were performed to evaluate their liquefaction potential. The test specimens originate from stratified silty soil deposits in southwestern Christchurch which did not typically have surface manifestations of liquefaction after the intense shaking of the 2011 Christchurch earthquake. The soil's undrained cyclic stress-strain responses indicate cyclic mobility. The differences in the cyclic responses of the soil with different amounts of non-plastic silt are subtle. Specimens with greater cyclic stiffness degradation typically had lower post-cyclic stiffness. The soil stiffness was significantly lower in post-cyclic tests than in monotonic tests due to the large differences in the initial effective stresses between the two types of tests, loss of strength, age, and fabric effects. The field-adjusted laboratory-based cyclic resistances agree with CPT-based cyclic resistances from simplified liquefaction triggering procedures. Both assessments indicate the silty soil deposits generated high excess pore water pressures and liquefied during the Christchurch earthquake even though surface manifestations of liquefaction were not typically observed at the considered sites. The absence of liquefaction manifestation at the stratified silty soil sites highlights the importance of their system response.

Deep Magma Transport Control on the Size and Evolution of Explosive Volcanic Eruptions

Explosive eruptions are the surface manifestation of dynamics that involve transfer of magma from the underground regions of magma accumulation. Evidence of the involvement of compositionally different magmas from different reservoirs is continuously increasing to countless cases. Yet, models of eruption dynamics consider only the uppermost portion of the plumbing system, neglecting connections to deeper regions of magma storage. Here we show that the extent and efficiency of the interconnections between different magma storage regions largely control the size of the eruptions, their evolution, the causes of their termination, and ultimately their impact on the surrounding environment. Our numerical simulations first reproduce the magnitude-intensity relationship observed for explosive eruptions on Earth and explain the observed variable evolutions of eruption mass flow rates. Because deep magmatic interconnections are largely inaccessible to present-day imaging capabilities, our results motivate the need to better image and characterize extant magma bodies.

Geological controls on brine discharge in Itumbula Salt Dam within the Rukwa Rift in Momba District, Tanzania

The Itumbula salt dam of the Rukwa Rift Basin is a depression formed through extraction of spring-derived salt crystals. Brine yield by springs which is the primary cause of significant amounts of salt in the dam required further geological investigations to understand yield controls. In this study, detailed field geological investigations in the salt dam and its surroundings were conducted to ascertain brine discharge controls. These included documentation of lithology and surface manifestations of brine deposition. Geophysical methods (i.e. magnetic and electric surveys) for studying geologic structures associated with brine deposits, and laboratory analysis of cations and anions (e.g. chlorides, bicarbonates or sulphates) essential to characterize composition of waters were also performed. The information on the springs discharge rate was retrieved from the previous studies. The magnetic profile revealed a very low magnetic anomaly across the salt dam, trending NW to SE direction, which is interpreted to be the main structure that controls fluid movements in the dam. Electric resistivity survey results delineated a low resistivity body in the central part of the dam interpreted as porous formation with saline water. Hydro-chemistry of the hot spring brines indicated high levels of sodium and chloride ions contents than magnesium, calcium, potassium, sulphate, and carbonate and bicarbonate ions, interpreted to be mature water with minimal water mixing. The structurally controlled brines of approximately 2.5 kg/s are discharged in the study area.&#x0D; Keywords: Geologic Structures, Brine, Salt Production, Momba, Rukwa Basin.

Integrated remote sensing and geophysical techniques for shallow base metal deposits (Zn, Pb, Cu) below the gossan zone at Kalabar, Western Aravalli Belt, India

Occurrences of small base metal deposits are reported along the western margin of Aravalli Belt in India. Surface manifestation of one such deposit is found to occur as gossan zone within the host rock of amphibolite in Kalabar area of Rajasthan State. Assessment of this occurrence through drilling technology is a time-consuming exercise, more expensive and requires huge manpower. In the present study, an attempt has been made to rediscover the mineral deposit in Kalabar area using remote sensing and High-resolution Electrical Resistivity Tomography (HERT) techniques. Spectral data analysis with Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor shows the characteristic mineral constituents of the gossan zone. 2D electrical resistivity tomograms helped in identifying a narrow vertical zone with low resistivity but high chargeability value up to a depth of 127.9 m. Geospatial analysis of the resistivity data provides the size of the sub-surface deposits. Several exploratory drillings confirm the existence of such deposit up to a depth of 180 m due to presence of highly conductive metallic ore body (Zn, Pb, Cu). Thus, a unique approach is adopted in mineral exploration technology through integrated analysis of surface to sub-surface information. HERT technique is found to be a cost-effective geophysical survey for identifying the geometry and type of shallow base metal deposits.

HILANG PANAS ALAMIAH DAERAH MANIFESTASI PANAS BUMI UNTUK ESTIMASI POTENSI SUMBER DAYA SPEKULATIF ENERGI PANAS BUMI DISEKITAR GUNUNG TAMPUSU

Geothermal energy is one of the new and renewable alternative energy sources that are environmentally friendly. Indonesia is one of the countries in the world that has large geothermal reserves. The appearance of a manifestation that appears to the surface indicates the potential for geothermal energy in an area. This study aims to calculate the amount of natural heat loss to determine the potential of speculative resources. Research using natural heat loss calculations is the initial stage in starting geothermal exploration. In the area around Mount Tampusu, Remboken District, Minahasa Regency, North Sulawesi Province, there are surface manifestations that can be seen from the heat loss and speculative resources. This research was conducted by taking data in the field and processing the data using the natural heat loss equation in each manifestation. Based on the research results, the total natural heat loss in manifestations around Mount Tampusu is 17,16 mW and the speculative resources are 171,6 mW.

Forward modelling of Kepler-band variability due to faculae and spots

ABSTRACT Variability observed in photometric light curves of late-type stars (on time-scales longer than a day) is a dominant noise source in exoplanet surveys and results predominantly from surface manifestations of stellar magnetic activity, namely faculae and spots. The implementation of faculae in light-curve models is an open problem, with scaling typically based on spectra equivalent to hot stellar atmospheres or assuming a solar-derived facular contrast. We modelled rotational (single period) light curves of active G2, K0, M0, and M2 stars, with Sun-like surface distributions and realistic limb-dependent contrasts for faculae and spots. The sensitivity of light-curve variability to changes in model parameters such as stellar inclination, feature area coverage, spot temperature, facular region magnetic flux density, and active band latitudes is explored. For our light-curve modelling approach we used actress, a geometrically accurate model for stellar variability. actress generates two-sphere maps representing stellar surfaces and populates them with user-prescribed spot and facular region distributions. From this, light curves can be calculated at any inclination. Quiet star limb darkening and limb-dependent facular contrasts were derived from MURaM 3D magnetoconvection simulations using ATLAS9. 1D stellar atmosphere models were used for the spot contrasts. We applied actress in Monte Carlo simulations, calculating light-curve variability amplitudes in the Kepler band. We found that, for a given spectral type and stellar inclination, spot temperature and spot area coverage have the largest effect on variability of all simulation parameters. For a spot coverage of $1{{\ \rm per\ cent}}$, the typical variability of a solar-type star is around 2 parts per thousand. The presence of faculae clearly affects the mean brightness and light-curve shape, but has relatively little influence on the variability.

Imprint of chemical weathering and hydrothermalism on the Ge/Si ratio and Si isotope composition of rivers in a volcanic tropical island, Basse-Terre, Guadeloupe (French West Indies)

A significant portion of the disproportionally high chemical weathering flux in volcanic island arcs may originate from hydrothermal fluid-rock interaction, thereby compromising the accurate estimate of atmospheric CO2 consumption rates. The objective of this study is to evaluate how the riverine Ge/Si ratio and Si isotopes, two well-established tracers of weathering, respond to hydrothermal inputs. The work took place in Basse-Terre, Guadeloupe, a tropical volcanic island with a dense river network, high chemical weathering fluxes and various hydrothermal surface manifestations. We characterized the Ge/Si ratio and δ30Si of 15 thermal springs, nine non-impacted (NI) rivers and 13 hydrothermally-impacted (HI) rivers. The soil solution from a highly weathered soil profile (Ferralsol) and a clayey-rock corresponding to the material exposed in an extinct hydrothermal system were also measured. A new purification method was successfully developed in order to allow the reliable measurement of Si isotopes in SO42−- and Cl−-rich thermal spring and HI river waters by mass spectrometry. Basse-Terre's thermal springs have variable Ge/Si ratios (0.05–21.03 μmol.mol−1) and δ30Si (0.71–1.50‰), but with no apparent relationship to the water compositional type. The Ge/Si ratio (0.15–2.57 μmol.mol−1) and Si isotope composition (0.26–1.21‰) values of the NI rivers reveal differences in the watersheds' weathering degree. Dissolution of Ge- and 28Si-rich secondary minerals explains the high Ge/Si and isotopically light composition of the northern NI rivers draining strongly weathered terranes. The Ge/Si ratio and δ30Si values measured for the NI and HI rivers overlap, implying that they cannot be used to diagnose hydrothermal contributions to river basins unambiguously. However, when combined with the Cl− and SO42− concentrations, the analysis of Ge and Si in the HI rivers suggests that water seeping through an extinct hydrothermal system produces SO4-rich drainages with distinctively lower Ge/Si ratios than those inferred for watersheds receiving thermal spring discharges associated with an active hydrothermal system. Overall, our results provide new constraints for applying and interpreting Ge/Si and Si isotope measurements to study weathering in volcanic environments.

Seismic Response Characteristics of Liquefiable Sites with and without Sediment Ejecta Manifestation

Dynamic nonlinear effective stress analysis of 45 well-documented liquefaction field case histories provides insights on the seismic response of sites where simplified liquefaction triggering procedures indicated liquefaction effects would be severe but either surface manifestations were not observed or inconsistent amounts of sediment ejecta were observed. The occurrence of sediment ejecta and its severity depend significantly on hydraulic processes after strong ground shaking ceases, which the simplified procedures do not consider. Postshaking advection processes govern the amount of upward seepage–induced artesian flow that determines ejecta severity. The ejecta potential index (EPI) captures these key aspects of the hydraulic processes of liquefaction manifestation. EPI can be sensitive to variables such as hydraulic conductivity, groundwater level, and input ground motions. However, it proves to be a useful index that correlates well to the severity of ejecta manifestation observed in the field case histories. Sites with severe ejecta have high EPI values, and sites without ejecta have low EPI values.

Geological Controls on Thermal Manifestation Occurences in Batu Gede and Batu Kapur, Subang Regency: A Preliminary Result

Batu Gede and Batu Kapur are administratively located in Subang Regency, West Java, precisely in the northern part of Tangkuban Perahu Geothermal Working Area. Characteristics of the manifestations in Batu Gede and Batu Kapur are generally bicarbonate neutral pH warm springs and their location exposed in the foot of Tangkuban Perahu Volcano. Despite the similar chemical characteristic of those two manifestations, there is a significant characteristic difference between them. Spring with low pH with the pungent smell emerges in the Batu Gede not far from neutral pH bicarbonate warm spring. The aim of this research is to determine control of the occurrence and relationship of manifestation in both areas by conducting geological mapping. Surface manifestations are controlled by a geological process associated with primary and secondary permeability. Both manifestations emerge dominantly in the control of fault as a secondary permeability. Primary permeability also controls the occurrence of manifestations but not significant. Batu Gede manifestations are dominantly controlled by overstepping structure, while Batu Kapur are dominantly controlled by intersections between structures. Based on high content of SO4 −2, acid pH, and the presence of sulfur, the acid manifestation might be correlated with magmatic activity beneath Batu Gede’s manifestation.

Etermination of Geothermal Reservoir Zone of Sorik Marapi, Mandailing Natal, North Sumatra

The Sorik Marapi Geothermal Power (SMGP) Field is located in Mandailing Natal (350 km to the southeast from Medan), North Sumatra. This study needed alteration mineral data validation with fluid geochemical characteristics from surface manifestations, and production wells were determined the geothermal reservoir zone. Therefore geothermometer and geoindicator calculations were used. Laboratory tests were carried out on 38 surface manifestations and 11 cutting samples of exploration well. Manifestations in this area include hot springs, fumaroles, and steaming ground. Alteration minerals found in the study area are anhydrite, epidote, calcite,chlorite, muscovite, pyrophyllite, and zeolite. The alteration zone is located in the zeolite zone, the epidote zone,and the anhydrite-sericite zone. Geochemical manifestations of surface and production wells containing chloride water, sulfate water, sulfate-chloride water, and bicarbonate water. The estimated reservoir temperature of SH-01 well shows temperatures ranging from 240–280˚C, SH-02 well shows temperatures of 249.89–302.92˚C, SH-03 well show temperatures of 231.09–280˚C. The mineral geothermometer calculation, which is correlated with the geochemical fluid geothermometer, shows valid results. This is evident from the estimated reservoir temperatures of the two geothermometers.

Ocular surface disease in psoriatic patients in a developing country.

To evaluate ocular surface changes among patients with psoriasis in Malaysia, a developing country in Southeast Asia. An interdisciplinary case-control study (60 psoriasis patients and 40 control subjects) to look at the differences in ocular surface manifestations between patients with psoriasis and a group of age-, gender- and ethnicity-matched healthy controls. One hundred and twenty eyes of 60 patients with psoriasis and 80 eyes of 40 healthy controls without psoriasis were included in the study. Mild-to-moderate psoriasis was found in 42 patients (70%), while 18 patients (30%) had severe psoriasis. Psoriatic arthritis was found in 19 patients (32%). Of the 60 psoriatic patients, the prevalence of ocular involvement was 65% (39/60), in which 32% (19/60) had dry eyes, 27% (16/60) had lid margin abnormalities, 33% (20/60) had cataract, and one had history of anterior uveitis. Compared to controls, ocular surface of psoriatic patients showed more eyelid margin abnormalities, higher meibomian gland loss and lower tear filmbreak-up time. The estimated odds ratio for dry eyes in the psoriasis group was 2.2 (95% CI: 0.8-6.9). Ocular surface disorders encompassing eyelid margin abnormalities, meibomian gland loss and tear dysfunction occur at an earlier and higher rate among psoriatic patients.