Topography Device Research Articles

Assessing blink dynamics with non-noticeable method

PurposeThe purpose of the study was to demonstrate the feasibility of blink dynamics with a contactless, non-noticeable method without any visible light being reflected to the participant’s eye by the device, and to investigate the blink dynamics parameters in 39 participants whose blink dynamics were examined with this method. It was also aimed to explain the potential of corneal topography devices for non-noticeable blink dynamics and elucidate some tips to device manufacturers to make them practical. MethodsA one-minute real-time video image in the meibography module of the scheimpflug camera-based corneal topography device was recorded in the slow motion mode of the mobile phone. Detailed analysis of blink dynamics was made by advancing the video images manually at 10 ms intervals. Lid Closing Time (LCT), Lid Opening Time (LOT), third Interblink Interval times (IBI(3)), fifth Interblink Interval times (IBI(5)), Number of Blinks Per Minute (NoB), Number of Complete Blinks Per Minute (NoCB), Number of Incomplete Blinks Per Minute (NoICB) were investigated. ResultsThe average NoB, NoCB, and NoICB (blinks/minute) with ± standard deviation (SD) values were found to be 22.9 ± 14.4; 14.5 ± 12.4 and 8.4 ± 8, respectively. The average IBI(3) time(seconds) with ± SD was measured as 3.4 ± 4.5. The average IBI(5) time (seconds) with ± SD was 3.9 ± 3.7 The average LCT time (milliseconds) with ± SD was found to be 91.9 ± 36.9 in the 4 different blinks analyzed. The average LOT time (milliseconds) with ± SD was found to be 582.6 ± 196.5 in the 3 different blinks analyzed. ConclusionsBlink dynamics can be examined in detail with corneal topography devices in a non-contact, no visible light, and most importantly, non-noticeable manner. Existing video imaging modules of corneal topography devices have the potential to investigate blink dynamics. It is anticipated that the clinical use of blink dynamics, which can be performed practically, will increase, particularly in the monitoring of ocular surface and neurological diseases.

The Effects of Changes in Cigarette Menthol Content on Acute Nicotine Pharmacology and Smoking Topography.

Menthol influences the appeal and addictiveness of cigarette smoking, however the data regarding menthol's effects on nicotine pharmacokinetics (PK) and smoking topography are inconsistent. This study investigated the impact of different cigarette menthol levels on nicotine pharmacology and smoking topography in current menthol smokers. The study was a double-blind, randomized, four-period, crossover study to investigate the effects of smoking cigarettes with varying menthol content (0, 3, 6, and 12mg menthol) on nicotine PK, smoking topography, and subjective effects in current menthol smokers. Each experimental session consisted of a prescribed use session, followed by 145min of no smoking and a 1-h ad libitum smoking session. Serial blood samples were collected; smoking topography was recorded using CReSS Lab topography device. There was no significant effect of menthol on nicotine PK after prescribed smoking of cigarettes with varying menthol contents. During ad libitum smoking, there was significantly smaller total puff volume and puff duration in the 12mg menthol condition compared to other menthol conditions. Subjective and sensory measures indicated significantly higher overall positive ratings for the 3mg and 6mg menthol cigarettes compared to the 0mg menthol cigarette; the 12mg menthol cigarette was less liked and harsher than the 3mg condition. These findings suggest that menthol, at concentrations reflecting the marketplace (3-6mg), contributes to positive subjective smoking experiences among menthol smokers, but does not have a significant effect on nicotine PK or smoking topography in an acute laboratory setting. While our data indicate that varying menthol content does not have a significant impact on nicotine's pharmacological effects under acute exposure conditions, these data highlight the contribution of menthol's flavor and sensory effects to product preference and positive smoking experiences, which facilitate repeated experimentation, progression to regular use, and subsequent dependence.

Construction and evaluation of a neurofeedback system using finger tapping and near-infrared spectroscopy.

Neurofeedback using near-infrared spectroscopy (NIRS) has been used in patients with stroke and other patients, but few studies have included older people or patients with cognitive impairment. We constructed a NIRS-based neurofeedback system and used finger tapping to investigate whether neurofeedback can be implemented in older adults while finger tapping and whether brain activity improves in older adults and healthy participants. Our simple neurofeedback system was constructed using a portable wearable optical topography (WOT-HS) device. Brain activity was evaluated in 10 older and 31 healthy young individuals by measuring oxygenated hemoglobin concentration during finger tapping and neurofeedback implementation. During neurofeedback, the concentration of oxygenated hemoglobin increased in the prefrontal regions in both the young and older participants. The results of this study demonstrate the usefulness of neurofeedback using simple NIRS devices for older adults and its potential to mitigate cognitive decline.

Comparison of keratometric values and anterior segment parameters measured using Scheimpflug Sirius topography and Lenstar biometry.

This study aimed to evaluate the consistency of preoperative keratometric values, anterior segment, and intraocular lens (IOL) power measurements in patients with cataract and no comorbidities using the Sirius topography device (CSO, Italy) and Lenstar LS 900 (Haag-Streit AG, Köeniz, Switzerland). Patients with grade 2 and 3 cataracts who applied to Ophthalmology Clinic of Dışkapı Yıldırım Beyazıt Education and Research Hospital, University of Health Sciences and planned for cataract surgery were included the study. Forty eyes with cataract from 40 patients were taken in the study. All patients underwent preoperative assessment using a combined Scheimpflug-Placido disc-based tomography device (Sirius) and Lenstar before cataract surgery. Keratometric measurements, such as flat keratometry (K1), steep keratometry (K2), and maximum keratometry (Kmax), and anterior segment parameters, white-to-white (WTW) distance, IOL power, astigmatism (AST), anterior chamber depth (ACD), aqueous depth (AD), and central cornea thickness (CCT), were recorded. There were significant differences between K1Lenstar and K1Sirius, K2Lenstar and K2Sirius, KmaxLenstar and KmaxSirius, WTWLenstar and WTWSirius, and IOL powerLenstar versus IOL powerSirius. However, there were insignificant differences between ASTLenstar and ASTSirius, ACDLenstar versus ACDSirius, ADLenstar and ADSirius, and CCTLenstar and CCTSirius variables. Furthermore, it was found that Sirius measured significantly higher than Lenstar, especially in terms of IOL power. Significant differences were observed between Lenstar and Sirius in terms of keratometric values, WTW distance, and IOL power. The IOL power value measured with Sirius was found to be higher than the IOL power value measured with Lenstar.

The effect of a preservative-free prostaglandin analogue on the condition of the ocular surface in patients with glaucoma

PURPOSE. The study aimed to evaluate the antihypertensive effectiveness and the condition of the ocular surface in patients with glaucoma during monotherapy with the drug Traviolan® (travaprost 0.05%).METHODS. This longitudinal, randomized, prospective study included 27 patients (59.6% women, 40.4% men; mean age 64.1±6.4) with uncompensated primary open-angle glaucoma in early and moderate stages receiving mono-therapy with β-blockers or carbonic anhydrase inhibitors. This was a longitudinal, randomized, prospective, observational study. All patients underwent a complete ophthalmological examination and assessment of dry eye symptoms using a questionnaire (Ocular Surface Disease Index, OSDI). An objective assessment of the condition of the ocular surface was carried out using the Sirius corneal topography device, which is used for assessment of tear film breakup time (TBUT). All patients were re-examined after 12 weeks.RESULTS. Intraocular pressure was significantly reduced at all study visits and amounted to 5.9±2.8 mm Hg at week12 (25.9%). There was a significant reduction in symptoms of dry eye, irritation, itching, and foreign body sensation (p<0.05 for each parameter). A significant improvement was also noted in terms of the condition of the ocular surface, and in most patients the symptom complex was classified as mild dry eye syndrome (p<0.05). Additionally, there was also a significant improvement in the OSDI score (p<0.05) with a mean of 17.95±5.35 points. The tear film breakup time by the end of observation increased by 4.1±2.3 sec and amounted to 7.4±3.1 sec.CONCLUSION. The drug Traviolan® has high antihypertensive effectiveness and good tolerability, and improves the condition of the ocular surface.

Prevalence of keratoconus and subclinical keratoconus in subjects with two or more diopters (D) of astigmatism using pentacam derived parameters

Keratoconus is a common progressive asymmetric, bilateral, ectatic corneal disorder that arises due to biomechanical and structural defects in organization of corneal collagen. It is characterized by axial protrusion of cornea and thinning of corneal stroma which deforms the shape of cornea leading to myopia and irregular astigmatism with decreased vision. This is a prospective cross-sectional study. All the patients within age group of 8-45 years who attended Outpatient Department of a Tertiary Care Hospital, Ajmer, with signs and symptoms of keratoconus or with astigmatism ≥2D with no previous history of ocular trauma or surgery were evaluated and a complete ophthalmic examination was done including the best corrected visual acuity, retinoscopy, slit lamp biomicroscopy and fundus examination and the findings were recorded. Only subjects with no other signs and symptoms of other ocular pathology were included. 334 eyes (167 subjects) were included in this study and among 334 eyes, 291 eyes had ≥2 D Astigmatism, 152/167 (91.02%) right and 139/167 (83.23%) left eyes. Mean age of the patients was 19.6±9.09 years ranging from 8 to 45 years. 50.3% of study subjects were females and 49.7% were males. Overall, in both eyes, prevalence of astigmatism was found to be 73.88%, FFKCN was 10.31% and KCN was found 15.81% among the study population having ≥2 D astigmatism. Patients with astigmatism of ≥2D who attend outdoor clinics should be evaluated with corneal tomography for early diagnosis, even if visual acuity is not significantly affected. Pentacam gives a more accurate diagnosis than corneal topography devices used conventionally, particularly in keratoconus suspicious eyes.

Comparison of intraocular pressure measurements obtained by icare pro tonometer, non-contact tonometer and Goldmann applanation tonometer in healthy individuals

The goal of this paper was to compare the intraocular pressure (IOP) measurements obtained via iCare Pro rebound (IRT), non-contact tonometry (NCT), and Goldmann applanation (GAT) tonometry in healthy subjects. One hundred and twenty-five healthy individuals were included in this study. The participants' IOP measurements were obtained via non-contact tonometry. After routine ophthalmic examination, central corneal thickness (CCT) was measured with a topography device. Intraocular pressure was measured via iCare Pro rebound tonometry. After waiting for 5minutes, three measurements were taken with GAT under topical anaesthesia, and their means were recorded. Interdevice agreement was evaluated with the intraclass correlation coefficient (ICC) and Bland-Altman analysis. The mean IOP measurements for NCT, IRT, and GAT were 15.97±2.99, 17.47±2.86, and 16.46±2.68mmHg, respectively. The mean difference between NCT and GAT was -0.49± 1.89mmHg, the mean difference between IRT and GAT was 1.01±1.90mmHg, and the mean difference between NCT and IRT was -1.50±2.02mmHg. Agreement between devices was found to be >0.8 for each tonometry ICC. There were significant positive correlations between the measurements obtained via these three instruments and CCT. In this study, IOP was measured slightly lower with NCT than GAT, but it was about 1mmHg higher with IRT than GAT on average. All three devices appeared to be affected by CCT, with NCT being the most affected in this regard. The three instruments can be used for routine inspection and screening. However, considering the differences in the measurements obtained by using them, it is clear that following up IOP measurements with GAT measurements is beneficial in advanced glaucoma patients.

Repeatability of pupil diameter measurements using three different topography devices.

To evaluate the intra- and inter-device repeatability of pupil diameter measurements using three different devices in patients prior to corneal refractive surgery. We examined preoperative measurements from a total of 204 eyes (102 patients) scheduled for corneal refractive surgery at two private centers between July and December 2021. Three consecutive scans were performed with three different devices (Sirius anterior segment analyzer, Pentacam HR, IOLMaster 500) in the same session by the same examiner under standardized conditions. To assess the intra- and inter-device repeatability, we calculated the Intraclass Correlation Coefficient (ICC) and demonstrated results using Bland-Altman plots. The measurement accuracy (intra-device repeatability) of Sirius and IOLMaster was comparable (ICC = 0.64 and 0.61, respectively), with almost no statistically significant differences. Sirius showed the highest measurement accuracy among the three devices. Pentacam measurements resulted in lower precision, with an ICC of 0.09. The agreement between the pairs of devices (inter-device repeatability) was low (wide LoA ranges, Table 5). In this study, the intra-device repeatability of Sirius and IOLMaster was higher than that of the Pentacam, although it did not achieve an optimal level across all three devices. The three devices examined cannot be used interchangeably.

Changes in corneal high order aberrations and anterior chamber parameters following scleral fixated intraocular lens implantation

BackgroundTo evaluate the change in corneal high order aberrations (HOAs) and anterior chamber parameters following scleral fixation in aphakic patients using the Scheimpflug camera system. MethodsThis retrospective study included patients who were aphakic after phacoemulsification surgery and underwent scleral-fixed intraocular lens (SF-IOL) implantation with Z suture technique between 2010 and 2022. Preoperative and postoperative best corrected visual acuity (BCVA), anterior segment parameters and corneal aberrations were evaluated with a combined Scheimpflug-Placido disk corneal topography device (Sirius Costruzione Strumenti Oftalmici, Florence, Italy). The following values were recorded: Simulated keratometry (SimK), flat meridian (K1), steep meridian (K2), iridocorneal angle (ICA), temporal anterior chamber angle (T-ACA), nasal anterior chamber angle (N-ACA), horizontal anterior chamber diameter (HACD), anterior chamber volume (ACV), corneal volume (CV), total Root Mean Square (RMS), high order aberrations (HOAs), spherical aberration, coma, trefoil, quadrifoil, and secondary astigmatism. ResultsThe study included 31 eyes of 31 patients (mean age: 63.00 ± 19.41 years, 17 males/14 females). Postoperative BCVA was better than preoperative BCVA (p = 0.012). Postoperatively, there was a statistically significant increase in ACV and CV values and a statistically significant decrease in K2 (p = 0.009, p = 0.032, p = 0.015). Preoperative T-ACA and preoperative and postoperative ACV were negatively correlated with postoperative intraocular pressure (r=-0.427 p = 0.033, r=-0.406 p = 0.032 and r=-0.561 p = 0.001). There were statistically significant postoperative increases in corneal RMS, trefoil and HOAs for 3 mm pupil diameter (p = 0.0177, p = 0.001, p = 0.031) and in corneal RMS, trefoil and quadrifoil aberrations for 6 mm pupil diameter (p = 0.033, p = 0.001, p = 0.001). ConclusionsIn conclusion, SF-IOL implantation with Z-suture technique used for visual rehabilitation of aphakic patients may affect visual quality by increasing corneal HOAs while improving visual acuity.

Kornea Parametrelerindeki Değişikliklerin Değerlendirilmesi: Prospektif Klinik Çalışma

Objective: To determine the changes in corneal parameters of the normal population with age using corneal topography. Material and Methods: This prospective study included 275 right-eye measurements from a total of 275 healthy participants. The participants were divided into 4 groups according to their age: 6 to 20 years (Group 1), 21 to 40 years (Group 2), 41 to 60 years (Group 3), and over 60 years (Group 4). Central corneal thickness (CCT), central 10 mm corneal volume (Cvol), keratometry (K) values, corneal astigmatism (Ast), and axis values obtained with a Sirius topography device were recorded. Results: The mean age of the participants was 35.94±21.04 (range 6 to 77). There was a significant difference in CCT, Cvol, and Ast measurements between the groups (p<0.001). Regression analysis found a decrease of 4.6 µm in CCT and 0.6 mm3 in Cvol for every 10 years. There was a significant negative correlation between age and CCT and Cvol (r=-0.281, r=-0.336, respectively). There was a statistically significant change in the astigmatic axis values in accordance with with-the rule (WTR) and against-the rule with age. There was a significant difference in overall and Group 1 and 2 K values in the evaluation according to sex. Conclusion: CCT, Cvol, and Ast values decrease significantly with age. Axis values shift from WTR to against-to-rule with age. Knowledge of these changes can help in the prediction of the longterm results of corneal diseases, ophthalmic operations, and intraocular lens power calculations.

Correlation between Placido-disc and rotating Scheimpflug keratometric findings before and after corneal crosslinking in children with keratoconus.

To evaluate correlation between Placido-disc and rotating Scheimpflug keratometric findings in children with progressive keratoconus (KC) before and after corneal crosslinking (CXL) and investigate whether these limits of agreement varied according to disease severity. Department of Ophthalmology of São Paulo Hospital, São Paulo, Brazil. Prospective nonrandomized open study. Data obtained using rotating Scheimpflug-based tomography and Placido-disc-based topography devices were collected from preoperative and last follow-up postoperative children with KC operated on using standard CXL protocol. Correlation and agreement analyses were performed between the 2 devices before and after CXL to obtain keratometric (K) findings. 44 eyes from 44 patients aged 8 to 16 years were analyzed at all timepoints. All parameters were found to be strongly correlated before ( r = 0.84 to 0.99, P < .001) and after ( r = 0.93 to 0.99, P < .001) CXL. The mean Scheimpflug measurements of flat K, steep K, Kmax, mean K, and corneal astigmatism were higher than Placido-disc measurements in a preoperative period. This mean difference decreased in postoperative, but, with exception of Kmax and corneal astigmatism, Scheimpflug measurements remained higher. The mean parameter measurements from both devices decreased after CXL; 95% limits of agreement between instruments were wide for all parameters and decreased in postoperative and in mild KC. Keratometry measurements obtained using rotating Scheimpflug and Placido-disc technology were found to be closely correlated but not interchangeable before and after CXL in pediatric patients. Agreement between devices was better after CXL and in mild KC than in advanced KC.

Tear film impairment and meibomian gland loss in patients with polycystic ovary syndrome.

The aim of this prospective study is to comparatively assess the tear film, meibomian gland (MG), cornea and anterior chamber parameters and also subjective ocular complaints in patients with polycystic ovary syndrome (PCOS) and healthy control subjects. We included 53 eyes of the 53 patients diagnosed with PCOS and 57 eyes of the 57 healthy control subjects (who are non-pregnant, none of the following clinical findings of male pattern hair loss, hirsutism or acne and with regular menstrual cycles, who have no laboratory findings in her medical history that indicate hyperandrogenism, and who have ovaries that appear to be normal ultrasonographically. All subjects were referred to the masked ophthalmologist by the obstetrician and gynecologist. Participants underwent evaluation of the non-invasive tear film break-up time test (NI-BUT); loss of MGs by non-contact meibography, evaluation of cornea and anterior chamber parameters, and evaluation of subjective ocular complaints using the ocular surface disease index (OSDI). The mean age of PCOS group and controls was 25.08 ± 4.88 and 25.44 ± 5.00years, respectively. There was no statistically significant difference between the PCOS and control groups in terms of age (p = 0.732). Mean non-invasive first tear film breakup times (NIF-BUT) values of PCOS group and controls were 6.15 ± 4.99 and 10.48 ± 5.81s, and mean non-invasive average tear film breakup times (NIAvg-BUT) values of PCOS group and controls were 8.48 ± 4.27 and 11.94 ± 4.64s, respectively; both cases refer to a significant difference between the groups (p = 0.000). In PCOS group, loss of MG in the upper lids was 40.21%, in the lower lids was 53.45%; on the other hand, in control group 15.76% and 21.47%, respectively; both cases refer to a significant difference between the groups (p = 0.000). The number of patients with abnormal OSDI scores (scores ≥ 13 points) was significantly higher in PCOS group (54.7%) than in controls (19.3%) (p = 0.000). Anterior chamber volume (ACV) measured by the topography device in PCOS group was significantly lower (156.5 and 167.4) (p = 0.024). Findings of this study indicated that tear film stability impaired in patients with PCOS and that this impairment was accompanied by the loss of MG, which play a key role in tear film stability.

The repeatability of corneal topography measurements in severe Dry Eye disease

BackgroundTo determine the repeatability of corneal topography measurements in severe dry eye disease (DED). A comparison of corneal topography parameters between severe DED and healthy subjects was a secondary goal of this study.MethodsSixty-nine patients with severe DED and 46 healthy subjects were enrolled in the study. All participants underwent repeated corneal topography measurements with Pentacam (Oculus, Germany) within a half hour time. Both eyes of the participants were used in statistical analysis. A further subcategorization of severe DED patients was performed according to Ocular Surface Disease Index (OSDI) scores: 32–50, 51–70 and 71–100. The repeatability of corneal parameters was assessed with correlation coefficients (CC).ResultsThe mean age of dry eye patients and healthy subjects were 40.8 ± 13.2 (17–66) and 39.8 ± 8.2 (18–61) years (p:0.604) respectively. No significant differences were found between severe DED and control groups according to analysed corneal parameters in both eyes (p:>0.05). All CCs were greater than 0.9 in severe DED group (p:<0.001). All CCs were also greater than 0.9 in severe DED patients among different OSDI groups (p:<0.001).ConclusionsCorneal topography measurements are highly repeatable in severe DED with Pentacam. This is the first report about this topic. Nonetheless, further studies are needed with different topography devices for validation.

Analyzing Impact of Mouthpiece-based Puff Topography Devices on Smoking Behavior using Wearable Sensors.

Detailed assessment of smoking topography (puffing and post-puffing metrics) can lead to a better understanding of factors that influence tobacco use. Research suggests that portable mouthpiece-based devices used for puff topography measurement may alter natural smoking behavior. This paper evaluated the impact of a portable puff topography device (CReSS Pocket) on puffing & post-puffing topography using a wearable system, the Personal Automatic Cigarette Tracker v2 (PACT 2.0) as a reference measurement. Data from 45 smokers who smoked one cigarette in the lab and an unrestricted number of cigarettes under free-living conditions over 4 consecutive days were used for analysis. PACT 2.0 was worn on all four days. A puff topography instrument (CReSS pocket) was used for cigarette smoking on two random days during the four days of study in the laboratory and free-living conditions. Smoke inhalations were automatically detected using PACT2.0 signals. Respiratory smoke exposure metrics (i.e., puff count, duration of cigarette, puff duration, inhale-exhale duration, inhale-exhale volume, volume over time, smoke hold duration, inter-puff interval) were computed for each puff/smoke inhalation. Analysis comparing respiratory smoke exposure metrics during CReSS days and days without CReSS revealed a significant difference in puff duration, inhale-exhale duration and volume, smoke hold duration, inter-puff interval, and volume over time. However, the number of cigarettes per day and number of puffs per cigarette were statistically the same irrespective of the use of the CReSS device. The results suggested that the use of mouthpiece-based puff topography devices may influence measures of smoking topography with corresponding changes in smoking behavior and smoke exposure.

Validation of a High Flow Rate Puff Topography System Designed for Measurement of Sub-Ohm, Third Generation Electronic Nicotine Delivery Systems.

There are few known puff topography devices designed solely for gathering electronic cigarette puff topography information, and none made for high-powered sub-ohm devices. Ten replicate Bernoulli flow cells were designed and 3D printed. The relationship between square root of pressure difference and flow rate was determined across 0–70 L/min. One representative flow cell was used to estimate puff volume and flow rate under six simulated puffing regimes (0.710 L, 2.000 L and 3.000 L, at low and high flow rates) to determine the system’s accuracy and utility of using dual pressure sensors for flow measurement. The relationship between flow rate and square root of pressure differential for the ten replicate cells was best fit with a quadratic model (R2 = 0.9991, p < 0.0001). The higher-pressure sensor was accurate at both low and high flow rates for 0.71 L (102% and 111% respectively), 2.00 L (96% and 103% respectively), and 3.00 L (100.1% and 107% respectively) but the lower-pressure sensor provided no utility, underpredicting volume and flow. This puff topography system generates very little resistance to flow, easily fits between user’s atomizer and mouthpiece, and is calibrated to measure flows up to 70 L/min.

Instability of Tear Film after Novel Coronavirus Disease: A Noninvasive and No Contact Method by a Scheimpflug-Placido Disc Topographer.

To compare the topographical tear film break-up time (T-BUT) between individuals recovering from COVID-19 and control subjects using a noninvasive and noncontact technique with a Scheimpflug-Placido disc topographer. One-hundred and twenty-two eyes from 61 post-COVID-19 patients and 124 eyes from 62 control subjects were included in this prospective study. All participants underwent detailed ophthalmological examination including best-corrected visual acuity, intraocular pressure measurements, slit lamp examination, and fundoscopy as well as qualitative and quantitative evaluation of the noninvasive first tear film break-up time (NIF-BUT) and noninvasive average tear film break-up time (NIAvg-BUT) with T-BUT measured with a Sirius (CSO - Costruzione Strumenti Oftalmici S. r. l., Italy) corneal topography device. The mean NIF-BUT in post-COVID-19 and control patients was 5.2 ± 3.4 vs. 6.5 ± 3.2 sec, respectively. The mean NIAvg-BUT in the corresponding groups was 7.5 ± 3.5 vs. 8.8 ± 3.0 sec, respectively. Both NIF-BUT and NIAvg-BUT were significantly lower in the post-COVID-19 group than in controls (p = 0.004 vs. 0.020). Topographical tear film break-up at any time during the test (17 sec) was observed qualitatively in 79 eyes (64.8%) in the post-COVID-19 group and 57 eyes (46%) in the control group (p = 0.003). Moreover, temporal quadrant involvement occurred significantly more frequently in the post-COVID-19 group (p = 0.028). Tear film stability assessment based on T-BUT showed shorter NIF-BUT and NIAvg-BUT in post-COVID-19 patients as compared to the control group. Our results suggest that post-COVID-19 patients have impaired stability of tear film, and therefore require closer monitoring regarding dry eye. In addition, tear film instability in post-COVID-19 patients can be reliably detected using a noninvasive and noncontact technique that is more comfortable for both patients and physicians.

A Low-Cost, High-Throughput Digital Image Analysis of Stain Patterns on Smoked Cigarette Filter Butts to Estimate Mainstream Smoke Exposure.

Standard machine smoking protocols provide useful information for examining the impact of design parameters, such as filter ventilation, on mainstream smoke delivery. Unfortunately, their results do not accurately reflect human smoke exposure. Clinical research and topography devices in human studies yield insights into how products are used, but a clinical setting or smoking a cigarette attached to such a device may alter smoking behavior. To better understand smokers’ use of filtered cigarette products in a more natural environment, we developed a low-cost, high-throughput approach to estimate mainstream cigarette smoke exposure on a per-cigarette basis. This approach uses an inexpensive flatbed scanner to scan smoked cigarette filter butts and custom software to analyze tar-staining patterns. Total luminosity, or optical staining density, of the scanned images provides quantitative information proportional to mainstream smoke-constituent deliveries on a cigarette-by-cigarette basis. Duplicate sample analysis using this new approach and our laboratory’s gold-standard liquid chromatography/tandem mass spectrometry (LC/MS/MS) solanesol method yielded comparable results (+7% bias) from the analysis of 20 commercial cigarettes brands (menthol and nonmentholated). The brands varied in design parameters such as length, filter ventilation, and diameter. Plots correlating the luminosity to mainstream smoked-nicotine deliveries on a per-cigarette basis for these cigarette brands were linear (average R2 > 0.91 for nicotine and R2 > 0.83 for the tobacco-specific nitrosamine NNK), on a per-brand basis, with linearity ranging from 0.15 to 3.00 mg nicotine/cigarette. Analysis of spent cigarette filters allows exposures to be characterized on a per-cigarette basis or a “daily dose” via summing across results from all filter butts collected over a 24 h period. This scanner method has a 100-fold lower initial capital cost for equipment than the LC/MS/MS solanesol method and provides high-throughput results (~200 samples per day). Thus, this new method is useful for characterizing exposure related to filtered tobacco-product use.

Epithelium-off corneal cross-linking surgery compared with standard care in 10- to 16-year-olds with progressive keratoconus: the KERALINK RCT

Background Keratoconus is a disease of the cornea affecting vision that is usually first diagnosed in the first three decades. The abnormality of corneal shape and thickness tends to progress until the patient reaches approximately 30 years of age. Epithelium-off corneal cross-linking is a procedure that has been demonstrated to be effective in randomised trials in adults and observational studies in young patients. Objectives The KERALINK trial examined the efficacy and safety of epithelium-off corneal cross-linking, compared with standard care by spectacle or contact lens correction, for stabilisation of progressive keratoconus. Design In this observer-masked, randomised, controlled, parallel-group superiority trial, 60 participants aged 10–16 years with progressive keratoconus were randomised; 58 participants completed the study. Progression was defined as a 1.5 D increase in corneal power measured by maximum or mean power (K2) in the steepest corneal meridian in the study eye, measured by corneal tomography. Setting Referral clinics in four UK hospitals. Interventions Participants were randomised to corneal cross-linking plus standard care or standard care alone, with spectacle or contact lens correction as necessary for vision, and were monitored for 18 months. Main outcome measures The primary outcome was K2 in the study eye as a measure of the steepness of the cornea at 18 months post randomisation. Secondary outcomes included keratoconus progression, visual acuity, keratoconus apex corneal thickness and quality of life. Results Of 60 participants, 30 were randomised to the corneal cross-linking and standard-care groups. Of these, 30 patients in the corneal cross-linking group and 28 patients in the standard-care group were analysed. The mean (standard deviation) K2 in the study eye at 18 months post randomisation was 49.7 D (3.8 D) in the corneal cross-linking group and 53.4 D (5.8 D) in the standard-care group. The adjusted mean difference in K2 in the study eye was –3.0 D (95% confidence interval –4.93 D to –1.08 D; p = 0.002), favouring corneal cross-linking. Uncorrected and corrected differences in logMAR vision at 18 months were better in eyes receiving corneal cross-linking: –0.31 (95% confidence interval –0.50 to –0.11; p = 0.002) and –0.30 (95% confidence interval –0.48 to –0.11; p = 0.002). Keratoconus progression in the study eye occurred in two patients (7%) randomised to corneal cross-linking compared with 12 (43%) patients randomised to standard care. The unadjusted odds ratio suggests that, on average, patients in the corneal cross-linking group had 90% (odds ratio 0.1, 95% confidence interval 0.02 to 0.48; p = 0.004) lower odds of experiencing progression than those receiving standard care. Quality-of-life outcomes were similar in both groups. No adverse events were attributable to corneal cross-linking. Limitations Measurements of K2 in those eyes with the most significant progression were in some cases indicated as suspect by corneal topography device software. Conclusions Corneal cross-linking arrests progression of keratoconus in the great majority of young patients. These data support a consideration of a change in practice, such that corneal cross-linking could be considered as first-line treatment in progressive disease. If the arrest of keratoconus progression induced by corneal cross-linking is sustained in longer follow-up, there may be particular benefit in avoiding the later requirement for contact lens wear or corneal transplantation. However, keratoconus does not continue to progress in all patients receiving standard care. For future work, the most important questions to be answered are whether or not (1) the arrest of keratoconus progression induced by corneal cross-linking is maintained in the long term and (2) the proportion of those receiving standard care who show significant progression increases with time. Trial registration Current Controlled Trials ISRCTN17303768 and EudraCT 2016-001460-11. Funding This project was funded by the Efficacy and Mechanism Evaluation (EME) programme, a Medical Research Council (MRC) and National Institute for Health Research (NIHR) partnership. This will be published in full in Efficacy and Mechanism Evaluation; Vol. 8, No. 15. See the NIHR Journals Library website for further project information. The trial sponsor is University College London. This research was otherwise supported in part by the NIHR Moorfields Biomedical Research Centre and the NIHR Moorfields Clinical Research Facility, London, United Kingdom.

Evaluation of Pupillometric Parameters in Patients with COVID-19

ABSTRACT Purpose To investigate the pupillary diameter and pupillary light response in patients who have recovered from the COVID-19. Methods Thirty two eyes of 32 patients with a history of COVID-19 in the last two months and 32 eyes of 32 age and sex-matched healthy controls were included in this prospective study. All patients had neurological symptoms. Dynamic and static pupillometry measurements were performed with the Sirius (CSO, Italy) corneal topography device. Results Patients with COVID-19 had higher mean scotopic, mesopic, and photopic pupil diameters compared to the controls (p = .01, p = .04, p = .02, respectively). In dynamic pupillometry analysis, 0th, 2th, 8th and 16th second pupil diameter measurements were higher in COVID-19 patients (p = .02, p = .04, p = .04, p = .04, respectively). There were no differences in the average speed of pupillary dilatation (p > .05). Conclusion Our findings suggest that the pupillary response, an indicator of autonomic nervous system activity, may be affected in COVID-19 patients with neurological symptoms.

Changes in anterior segment parameters and presence of dry eye disease in patients with acromegaly: A Sirius topography study combined with meibography

PurposeTo investigate anterior segment parameters (ASPs) and dry eye disease (DED), including the status of the meibomian glands, in patients with acromegaly. MethodsIn this cross-sectional, comparative study, 36 acromegaly patients and 40 healthy sex- and age-matched controls were included. Participants received a comprehensive ophthalmological examination, including intraocular pressure measurements with Goldmann applanation tonometry (IOPGAT) and central corneal thickness corrected intraocular pressure (IOPCCT) measurements, and were evaluated for ASPs and DED. For ASPs, white-to-white (WTW), apical (ACT) and thinnest corneal thickness (TCT), corneal volume (CV), keratometry readings (K1, K2, and Kmean), anterior chamber depth (ACD) and volume (ACV), and iridocorneal angle (ICA) were obtained via Sirius topography. DED was assessed with Schirmer's test, tear breakup time (TBUT), and Ocular Surface Disease Index (OSDI) scores. Meibography scores (MSs) were obtained with the Sirius topography device. ResultsPatients had higher mean IOPGAT (P = .006), IOPCCT (P = .01), ACT (P = .024), and TCT (P = .005) but narrower ICA (P = .014) than controls. Although Schirmer's test did not differ between the groups (P = .442), patients had higher OSDI (P < .001), higher MS (P = .001), and shorter TBUT (P = .002). ConclusionPatients with acromegaly have greater IOP, greater corneal thickness, but narrower ICA than healthy individuals, as well as DED with increased MSs, which suggests meibomian gland dysfunction.