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Christian Nilsen,1 Morten Gundersen,1 Per Graae Jensen,1 Kjell Gunnar Gundersen,1 Richard Potvin,2 Øygunn A Utheim,3– 5 Bjørn Gjerdrum1 1Ifocus Eye Clinic, Haugesund, Norway; 2Science in Vision, Frisco, TX, USA; 3Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway; 4Department of Ophthalmology, Oslo University Hospital, Oslo, Norway; 5The Norwegian Dry Eye Clinic, Oslo, NorwayCorrespondence: Christian Nilsen, Ifocus Eye Clinic, Strandgaten 203, Bergen, 5004, Norway, Tel +47 97189598, Email christian@ifocusstord.noPurpose: The primary objective was to investigate if treatment with artificial tears affected the variability of keratometry measurements for subjects with dry eyes prior to cataract surgery. The secondary objectives were to investigate whether treatment with artificial tears improved refractive precision and whether subjects with non-dry eyes had better refractive precision than subjects with dry eyes.Design: Prospective randomized controlled trial with three arms.Patients and methods: Dry eye diagnostics according to DEWS II were performed, and subjects with dry eyes were randomized to no treatment (group A1) or treatment with artificial tears two weeks prior to cataract surgery (group A2), with the third group (Group B, non-dry eyes) as a control. Keratometry was performed twice at baseline and twice after two weeks at the time of cataract surgery with three different optical biometers. The change in mean variability of keratometry (average K and magnitude of vector differences) and percentages of outliers after two weeks versus baseline were compared for group A2. The refractive and astigmatism prediction errors were calculated eight weeks after cataract surgery and compared for all three groups.Results: One hundred thirty-one subjects were available for analysis. There was no statistically significant difference in the mean variability of keratometry or percentages of outliers for group A2 from baseline to the time of cataract surgery. There was no statistically significant difference in refractive precision (absolute error and astigmatism prediction error) between any groups.Conclusion: Subjects with dry eyes (treated and non-treated) achieved the same refractive precision and percentages of outliers as subjects with non-dry eyes. Treatment with artificial tears for two weeks appeared inadequate to significantly affect variability in biometric measurements for patients with dry eyes prior to cataract surgery. DEWS II criteria for DED may not be optimal in a cataract setting.Keywords: Cataract surgery, non-invasive keratography tear break-up time, ocular surface staining, osmolarity, artificial tears

Per Jensen,1 Christian Nilsen,1 Morten Gundersen,1 Kjell Gunnar Gundersen,1 Rick Potvin,2 Parisa Gazerani,3 Xiangjun Chen,4– 6 Tor P Utheim,3– 8 Øygunn A Utheim4,7,8 1Ifocus Eye Clinic, Haugesund, Norway; 2Science in Vision, Frisco, TX, USA; 3Faculty of Health Sciences, Oslo Metropolitan University, Oslo, Norway; 4Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway; 5Department of Ophthalmology, Sørlandet Hospital Arendal, Arendal, Norway; 6Department of Ophthalmology, Vestre Viken Hospital Trust, Drammen, Norway; 7Department of Ophthalmology, Oslo University Hospital, Oslo, Norway; 8The Norwegian Dry Eye Clinic, Oslo, NorwayCorrespondence: Per Jensen, Ifocus Eye Clinic, Sørhauggata 111, Haugesund, 5527, Norway, Tel +47 906 13 685, Email per@ifocus.noPurpose: To compare the effect of treatment with preservative-free dexamethasone, NSAIDs and trehalose/hyaluronic acid eye drops with the preservative benzalkonium chloride containing dexamethasone and NSAIDs after cataract surgery in dry versus non-dry eyes.Patients and Methods: In this prospective randomized intervention study, dry eye tests were performed before and 6 weeks after cataract surgery. Patients were considered as having dry eye, SDE (sign of dry eye), if at least one of the following dry eye tests were abnormal; corneal fluorescein staining (CFS), non-invasive keratograph breakup time (NIKBUT) or tear osmolarity. Patients with SDE were randomly assigned to one of two groups. Group 1 patients were treated with dexamethasone and bromfenac eye drops with the preservative benzalkonium chloride (BAC). Group 2 patients were treated with preservative-free dexamethasone and preservative-free diclofenac, as well as a preservative-free lubricant with trehalose and hyaluronic acid both before and after surgery. Patients with normal tear film status acted as the control group (group 3) and received same treatment as group 1.Results: A total of 215 patients were enrolled six weeks after surgery, the number of patients with SDE decreased significantly in groups 1 and 2 (p < 0.001). Subjective symptoms and objective measures including osmolarity, NIKBUT, CFS, and tear film thickness (TFT) improved after surgery, tear production remained unchanged, while corneal sensitivity and meibomian gland dysfunction (MGD) parameters worsened. In the control group with normal tear-film status, SDE increased significantly after the surgery (p < 0.001). There were no statistically significant differences in tear film parameters between the three groups after surgery.Conclusion: After cataract surgery, patients with mild to moderate dry eyes may experience improved tear film status and reduced symptoms. However, we found no additional beneficial effect on dry eye parameters with treatment with preservative-free dexamethasone, NSAIDs, and lubricants compared to preservative-containing eye drops.Keywords: sign of dry eye, cataract surgery, osmolarity, corneal fluorescein staining, non-invasive keratograph tear break-up time, ocular surface disease index, meibomian gland dysfunction

Christian Nilsen,1 Morten Gundersen,1 Per Graae Jensen,1 Kjell Gunnar Gundersen,1 Richard Potvin,2 Øygunn A Utheim,3– 5 Bjørn Gjerdrum1 1Ifocus Eye Clinic, Haugesund, Norway; 2Science in Vision, Frisco, TX, USA; 3Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway; 4Department of Ophthalmology, Oslo University Hospital, Oslo, Norway; 5The Norwegian Dry Eye Clinic, Oslo, NorwayCorrespondence: Christian Nilsen, Ifocus Eye Clinic, Strandgaten 203, Bergen, 5004, Norway, Tel +47 97189598, Email christian@ifocusstord.noPurpose: The primary objective was to investigate if subjects with dry eyes had increased variability of keratometry measurements prior to cataract surgery compared to subjects with non-dry eyes. Secondary objectives were to determine which separate signs affected keratometry.Patients and Methods: This study was part of a prospective interventional randomized controlled trial. After dry eye diagnostics were performed (signs only) subjects were divided into sign of dry eye (SDE) positive and negative groups. To investigate variability, we performed two keratometry measurements for each subject with three different optical biometers: Anterion (OCT optical biometer), Eyestar (combined OCT and reflection-based optical biometer), and Lenstar (reflection based-optical biometer).Results: One hundred and thirty-one subjects were available for analysis. The variability of astigmatism was significantly higher for subjects with hyperosmolarity compared to normal eyes for the Lenstar, as was the percentage of eyes with variability of astigmatism greater than 0.25 D. The percentage of eyes with variability of average K greater than 0.25 D was higher for subjects with non-invasive keratograph break-up time < 10 seconds (NIKBUT positive) compared to normal eyes for the Lenstar.Conclusion: Combined diagnostic criteria (signs only) showed no statistically significant differences for keratometry measurements between SDE positive and negative. Eyes with hyperosmolarity and NIKBUT positive showed statistically higher variability of keratometry measurements compared to normal eyes for Lenstar, but not for the Anterion or Eyestar biometers.Keywords: cataract surgery, sign of dry eye, non-invasive keratography tear break-up time, ocular surface staining, osmolarity

Bjørn Gjerdrum,1 Kjell Gunnar Gundersen,1 Christian Nilsen,1,2 Morten Gundersen,1,2 Per Jensen1,2 1Ifocus Eye Clinic, Stavanger, Norway; 2Faculty of Health Sciences, Oslo Metropolitan University, Oslo, NorwayCorrespondence: Bjørn Gjerdrum, Brønngata 36, Stavanger, 4008, Norway, Tel +47 415 11935, Email bjorn@ifocus.noPurpose: To evaluate the agreement of refractive predictability of a swept-source optical coherence tomography (SS-OCT) biometer, which uses segmental AL calculation, with another SS-OCT biometer, and an optical low coherence reflectometry (OLCR) biometer. The secondary objective was to describe the refractive outcomes, visual acuities, and the agreement of different preoperative biometric parameters.Patients and Methods: The study was a retrospective one-arm study of refractive and visual outcomes after successful cataract surgery. Preoperative biometric data were collected with two different SS-OCT device (Argos, Alcon Laboratories and Anterion, Heidelberg Engineering) and an OLCR device (Lenstar 900, Haag-Streit). The Barrett Universal II formula was used to calculate IOL power for all three devices. Follow-up examination was 1– 2 months after surgery. The main outcome measure, refractive prediction error (RPE), was calculated as the achieved postoperative refraction minus the predicted refraction for each device. Absolute error (AE) was calculated by reducing the mean error to zero.Results: The study included 129 eyes of 129 patients. The mean RPE was 0.06, − 0.14 and 0.17 D for the Argos, Anterion and Lenstar, respectively (p < 0.01). The Argos also had the lowest absolute RPE, while the Lenstar had the lowest median AE, but this was not statistically significant (p > 0.2). The percentages of eyes with RPE within ± 0.5 was 76%, 71%, and 78% for the Argos, Anterion, and Lenstar, respectively. The percentages of eyes with AE within 0.5 D was 79%, 84%, and 82% for the Argos, Anterion and Lenstar, respectively. None of these percentages were statistically significantly different (p > 0.2).Conclusion: All three biometers showed good refractive predictability with no statistically significant differences in AE or percentages of eyes within ± 0.5 D of RPE or AE. The lowest arithmetic RPE was found with the Argos biometer.Keywords: cataract surgery, IOL power, refractive predictability, SS-OCT biometer, segmental AL, OLCR biometer

Per Graae Jensen,1 Morten Gundersen,1 Christian Nilsen,1 Kjell Gunnar Gundersen,1 Rick Potvin,2 Parisa Gazerani,3 Xiangjun Chen,4– 6 Tor P Utheim,3,4,7,8 Øygunn A Utheim4,7,8 1Ifocus Eye Clinic, Haugesund, Norway; 2Science in Vision, Bend, OR, USA; 3Faculty of Health Sciences, Oslo Metropolitan University, Oslo, Norway; 4Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway; 5Department of Ophthalmology, Sørlandet Sykehus Arendal, Arendal, Norway; 6Department of Ophthalmology, Vestre Viken Hospital Trust, Drammen, Norway; 7Department of Ophthalmology, Oslo University Hospital, Oslo, Norway; 8The Norwegian Dry Eye Clinic, Oslo, NorwayCorrespondence: Per Graae Jensen, Ifocus Eye Clinic, Djupaskarvegen 64 b, Haugesund, 5561, Norway, Tel +47 906 13 685, Email per@ifocus.noPurpose: To determine the prevalence of dry eye disease (DED) in patients scheduled for cataract surgery in a Norwegian eye clinic.Patients and Methods: 218 patients scheduled for cataract surgery were examined for DED in one randomly selected eye and questioned regarding symptoms and risk factors. Patients were diagnosed with DED if they fulfilled the DEWS II criteria with symptom score > 12/100 with Ocular Surface Disease Index (OSDI) questionnaire, and the presence of any of the three signs: tear osmolarity > 307 mOsm/L in either eye or a difference in osmolarity between the two eyes of > 8 mOsm/L, corneal fluorescein staining (CSF) ≥ grade 2 and non-invasive tear film breakup time (NIKBUT) of < 10 seconds. Additional tests were the Standard Patient Evaluation of Eye Dryness (SPEED) questionnaire, tear meniscus height (TMH), Schirmer 1, tear film thickness (TFT), corneal sensitivity and meibography (meiboscore). Dry eye test outcomes were correlated with risk factors for DED.Results: The prevalence of DED was 55.5% according to the DEWS II criteria. The abnormal osmolarity percentage was 66.5, while 29.8% had shortened NIKBUT and 19.7% exhibited CFS ≥ 2. 57% had Schirmer 1 ≤ 10 mm/5 min, and 81.1% had a meiboscore of ≥ 1. 71.2% of subjects scored positive for DED symptoms using the OSDI questionnaire and 69.3% using SPEED. Logistic regression analysis showed that higher age correlated with a lower OSDI symptom score, reduced corneal sensitivity and increased meibomian gland atrophy. Female sex was associated with higher odds of having DED, abnormal NIKBUT and abnormal CFS. Ocular tests for DED did not correlate with OSDI symptom scores when assessed with Spearman`s rank analysis.Conclusion: The prevalence of DED in an elderly Norwegian population scheduled for cataract surgery is high and associated with female sex. There was a lack of correlation between signs and symptoms of DED.Keywords: dry eye disease, cataract surgery, corneal fluorescein staining, ocular surface, osmolarity, non-invasive keratograph tear break up time, NIKBUT, meibomian gland dysfunction

Christian Nilsen,1 Per Graae Jensen,1 Morten Gundersen,1 Øygunn A Utheim,2– 4 Bjørn Gjerdrum,1 Kjell Gunnar Gundersen,1 David Jahanlu,5 Rick Potvin6 1iFocus Øyeklinikk, Haugesund, Norway; 2The Norwegian Dry Eye Clinic, Oslo, Norway; 3Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway; 4Department of Ophthalmology, Oslo University Hospital, Oslo, Norway; 5Faculty of Health Sciences, Oslo Metropolitan University, Oslo, Norway; 6Science in Vision, Bend, OR, USACorrespondence: Christian Nilsen, iFocus Øyeklinikk, Strandgaten 203, Haugesund, 5004, Norway, Tel +47-97189598, Email christian@ifocusstord.noPurpose: The purpose of this study was to evaluate the diagnostic value of inter-eye osmolarity differences in relation to dry eye symptoms and other non-osmolar signs of dry eye disease.Patients and Methods: One hundred ninety one participants who attended a larger interventional study of dry eye disease prior to and after cataract surgery were analyzed for dry eye disease (DED). Dry eye diagnostics were performed for all subjects according to the DEWS II criteria: tear osmolarity was collected from both eyes with the TearLab system, non-invasive Tear film break up time (NIKBUT) was obtained on the test eye with Keratograph and ocular surface staining (OSS) was evaluated using the Oxford schema. The Ocular Surface Disease Index (OSDI) questionnaire was used to assess symptoms. Inter-eye osmolarity greater than 8, which is considered as a sign of DED according to the TearLab user manual, was evaluated and compared with other non-osmolar signs of DED.Results: The 191 subjects were divided into three groups according to osmolarity measurements. Sixty-five subjects had normal osmolarity (below 308 mOsmol/L in both eyes and less than 9 mOsmol/L difference between the eyes), 107 had high osmolarity (308 mOsmol/L or higher in one of the eyes) and 19 had an inter-eye difference > 8 mOsmol/L or higher, with neither eye having osmolarity higher than 307 mOsmol/L. Signs and symptoms in this last group were not correlated with the high osmolarity group or the normal group, though they appeared more similar to the normal group.Conclusion: The diagnostic value of inter-eye osmolarity difference in predicting symptoms or other non-osmolar signs of dry eyes appears weak. Our study suggests that the criterion of an inter-eye difference of 8 mOsmol/L is not a useful cut-off for diagnosing dry eyes based on osmolarity.Keywords: dry eye disease, osmolarity, DEWS II

Research into the radiation arising when a relativistically moving plasma/gas boundary passes between alternatively biased capacitor electrodes is presented. This work quantified the significance of laser depletion in limiting the frequency upshift conversion.

Excited by 5 ns, 8 kV voltage pulses, a 260 μm-diameter, 8mm long helium plasma jet was generated with a single-electrode configuration in ambient air. Application of fast high voltage pulses (⩾1012 V s-1) resulted in rapid acceleration of the microplasma plumes; within 5 ns the plume velocity reached 8×105 m/s, almost three times higher than that of the plasma jet generated with the pulsed voltage of the same amplitude but with a lower increase rate (1011 V s-1). Importantly, the ultrashort electric pulses were able to efficiently deposit energy in the plasma during the initiation process, which may be responsible for the rapid acceleration of the ionization wavefronts during the streamer onset, as well as efficient production of reactive plasma species including O(5P) and N+2 (B2Σ+u) via electron-induced processes. Emission spectral comparison between the plasma jets excited with 5 ns voltage pulses and with 140 ns voltage pulses showed enhanced O(5P) and N+2 (B2Σ+u emission by the shorter pulses than the longer ones, while the vibrational and rotational temperature for both plasma jets are at 3000K and 300 K, respectively. [ABSTRACT FROM AUTHOR]

Bjørn Gjerdrum,1 Kjell Gunnar Gundersen,1 Christian Nilsen,1,2 Morten Gundersen,1,2 Per Jensen1,2 1Ifocus Eye Clinic, Stavanger, Norway; 2Faculty of Health Sciences, Oslo Metropolitan University, Oslo, NorwayCorrespondence: Bjørn Gjerdrum, Ifocus Eye Clinic, Brønngata 36, Stavanger, 4008, Norway, Tel +47 415 11935, Email bjorn@ifocus.no

Presents information on a study which evaluated the penetration and equilibrium of the velocity distribution function of an initially monoenergetic electron beam. Calculation of the production of bulk electrons and excited atomic states in the plasma; Velocity distribution of nonthermal electrons during penetration of a Maxwellian plasma; Numerical solution of the Fokker-Plancl equation.

Presents a study that investigated the triggered breakdown in low-pressure hollow cathode discharges. Influence of the discharge conditions, geometry and trigger conditions on the time to breakdown in helium; Relation between the time to breakdown and the geometrical distribution of injected charge; Importance of the various parameters which can influence the time to breakdwon in pseudospark discharges.

Examines the switching characteristics of silicon and GaAs-based devices operating in the low- and high-field regimes. Characteristics of an ideal power switch; Applications of high-power switches; Steady-state analysis of silicon- and GaAs-based majority carrier devices; Advantage of photoconductive switches over optothyristors.

Deals with a study of the photoluminescence spectra of gallium arsenide (GaAs)/AlGaAs multiple-quantum well structures with varying thicknesses as a function of excitation intensity and polarization. Luminescence spectra of four different multi-quantum wells with different layer thickness; Experimental details; Results and discussion.

Presents information on a study which analyzed the anomalously large cathode emission observed in the superdense glow of pseudospark and back-lighted thyratrons. Description of the discharge geometry used in the experiments; Results for both electron temperature and density; Discussion on cathode emission and current balance.

Examines the lock-on effect in pulsed-power semiconductor switches. Outcome of the lock-on effect; Characteristics of the effect; Requirement of a certain minimum bias field for triggering lock-on.