Assessing neophyte response to daily disposable silicone hydrogel contact lenses: A randomised clinical trial investigation over one month.

OBJECTIVE: This randomised clinical trial assessed the impact on symptoms, tear film dynamics and ocular surface integrity of daily disposable silicone-hydrogel contact lenses (CLs) over a month, paying special attention to lid wiper epitheliopathy (LWE) and its implications for CL discomfort. METHODS: Neophyte CL wearers (n = 44, 21.09 ± 5.00 years old) were randomly assigned to either the experimental (n = 24) or control group (n = 20). Participants assigned to the experimental group were required to wear daily disposable CLs for 1 month for at least 8 h/day and 6 days/week. All participants were healthy subjects (no history of ocular surgery or active ocular disease) with spherical refractive errors between -8.00 and +5.00 D and cylindrical power <0.75 D. At the baseline and 1-month sessions, the Dry Eye Questionnaire 5 (DEQ-5) was completed, together with the measurement of tear film osmolarity with the TearLab osmometer, tear meniscus height (TMH) and lipid layer pattern (LLP) using a slit-lamp with Tearscope Plus attached, fluorescein break-up time (FBUT), maximum blink interval (MBI), corneal staining with fluorescein under cobalt blue light and LWE with lissamine green under slit lamp and halogen white light. RESULTS: At the baseline session, LWE showed a negative correlation with DEQ-5 (r = -0.37, p = 0.02). Significant differences in FBUT and LWE (p = 0.04) and a positive correlation between LWE and DEQ-5 (r = 0.49, p = 0.007) were observed at 1 month. Intrasession analysis at 1 month showed significant differences between the experimental and control groups in DEQ-5, FBUT and LWE (all p ≤ 0.02). Intersession analysis in the experimental group showed variations in DEQ-5, FBUT and LWE (all p ≤ 0.02) but no significant variation in the control group (all p ≥ 0.11). CONCLUSION: The presence of LWE was significantly correlated with higher symptom values in the DEQ-5. Also, participants in the experimental group presented higher values of LWE after 1 month of CL wear, in comparison with the control group.

Meibum Lipidomic Analysis in Evaporative Dry Eye Subjects.

Meibomian Glands (MG) are sebaceous glands responsible for the production of meibum, the main component of the Tear Film Lipid Layer (TFLL). The TFLL facilitates the spread of the tear film over the ocular surface, provides stability and reduces tear evaporation. Alterations in meibum composition lead to different ocular alterations like Meibomian Gland Dysfunction (MGD) and subsequent Evaporative Dry Eye (EDE). The aim of the present study was to investigate the composition and abundance of meibum lipids and their relationship with eyelid margin abnormalities, lipid layer patterns and MG status. The study utilizes a lipidomic approach to identify and quantify lipids in meibum samples using an Elute UHPLC system. This system considered all four dimensions (mass/charge, retention time, ion mobility and intensity) to provide the accurate identification of lipid species. Samples were categorized as healthy or low/no signs of alteration (group 1) or severe signs of alteration or EDE/MGD (group 2). The current investigation found differences in Variable Importance in Projection lipid abundance between both groups for the MGD signs studied. Changes in meibum composition occur and are related to higher scores in eyelid margin hyperaemia, eyelid margin irregularity, MG orifice plugging, MG loss and lipid layer pattern.

Clinical Effectiveness, Safety, and Compliance of Two Compounded Formulations of Tacrolimus Eye Drops: An Open-Label, Sequential Prospective Study.

Ophthalmic tacrolimus compounded formulations are usually made from the commercial intravenous presentation, which contains ethanol as a solubilizer due to the low solubility of tacrolimus. The use of cyclodextrins is presented as an alternative to ethanol, an ocular irritant excipient, to avoid its long-term irritant effects. Open-label, sequential, prospective study to compare effectiveness, safety, and adherence of a new formulation of 0.015% tacrolimus with cyclodextrins (TCD) versus 0.03% tacrolimus with ethanol (TE). The ocular evaluation was assessed by ocular signs, corneal staining, subjective questionnaires as Visual Function Questionnaire (VFQ-25) and Visual Analogue Scale (VAS) of symptoms, lacrimal stability, ocular redness, and intraocular pressure. Compliance was assessed by VAS of adherence and empirically (difference between theoretical and actual consumption). Clinical ocular signs and corneal staining score remained stable for most patients 3 months after switching formulations. The TCD formulation did not modify the tear stability and intraocular pressure of the treated patients compared to the TE formulation. TCD eye drops significantly decreased the subjective pain values on VFQ-25 scale and burning sensation on the VAS symptom scale in comparison to TE formulation after 3 months after the change to TCD formulation. The novel tacrolimus in cyclodextrins formulation is a promising alternative for treating inflammatory ocular pathologies refractory to first-line treatments.

Comparison Between Ocular Biometric Parameters and Intraocular Pressure With and Without Contact Lenses.

OBJECTIVES: To compare the values of central corneal thickness, anterior chamber depth (ACD), lens thickness (LT), vitreous length (VL), axial length (AL), and corneal-compensated intraocular pressure performed with and without contact lenses (CL). METHODS: Forty volunteer participants (16 men and 24 women, 24.2±2.9 years) were recruited. In a single visit, participants underwent autorefraction, keratometry, biometry, topography, pachymetry, and tonometry with the naked eye (without CL). Then, biometry, pachymetry, and tonometry were repeated twice wearing two CL (somofilcon A and nesofilcon A) fitted in a random order. RESULTS: Many of the ocular biometric values were affected by the use of CL during measurements (paired t test; all P ≤0.003), except for LT and VL (Wilcoxon test; both P ≥0.272). Corneal-compensated intraocular pressure was also affected by contact lens wear during measurements, obtaining lower values when wearing them (Wilcoxon test; all P ≤0.001). CONCLUSIONS: Central corneal thickness, ACD, AL, and corneal-compensated intraocular pressure measurements cannot be performed while wearing CL. However, LT and VL measurements were not affected by any contact lens use. In addition, it was observed that ACD results from both devices are not interchangeable either when measured with the naked eye or using any contact lens.

Meibomian gland secretion quality association with ocular parameters in university students during COVID- 19 restrictions.

PURPOSE: To determine if the Meibomian Gland (MG) secretion quality is associated with symptoms of ocular discomfort, hours of Video Display Terminals (VDT) use, eyelid margin abnormalities, conjunctival hyperemia, and Meibomian Gland Loss Area (MGLA) in a sample of university students. METHODS: An online survey that included an Ocular Surface Disease Index (OSDI) questionnaire and an extra question about hours of VDT use recruited an initial sample of 183 participants. Only 120 participants that fulfilled the inclusion criteria were scheduled for a battery of ocular surface and MG specific exam. The tests include: 1) meibometry, 2) slit lamp exploration of eyelid margin abnormalities (irregularity, hyperemia and MG orifices plugging), MG secretion quality and conjunctival hyperemia, and 3) Meibography. RESULTS: Significant positive correlations between the MG secretion quality and eyelid margin hyperemia, MG orifices plugging, MGLA, nasal conjunctival hyperemia, and temporal conjunctival hyperemia (Spearman Rho; all r>0.186, p<0.042) were found. Multivariate regression found association between OSDI with hours of VDT use (B=0.316, p=0.007), and eyelid hyperemia (B=0.434, p≤ 0.001). A statistical association between MG secretion quality and eyelid margin hyperemia, MG orifices plugging, MGLA and conjunctival hyperemia (Fisher's exact; all p<0.039) were found. Multivariate regression found association between MG secretion quality with MG orifices plugging (B=0.295, p=0.004) and meibometry (B=-0.001, p=0.029). CONCLUSION: Participants with higher values in MG secretion quality have higher values in eyelid margin hyperemia, MG plugging, MGLA, and conjunctival hyperemia. No direct relationship between MG secretion quality and hours of VDT use or OSDI were found.

Validation of a New Software Application for Tear Breakup Measurement.

SIGNIFICANCE: Tear film instability has been recognized as one key mechanism on dry eye disease. There is a need for new instruments, methods, or protocols to improve the repeatability and reproducibility of the tear film stability to facilitate its clinical evaluation use as a rapid and reliable primary diagnostic test. PURPOSE: The present pilot study aimed to validate a method to automatically measure the tear film breakup time (BUT). METHODS: A total of 264 videos of BUT were randomly selected among the clinical history of subjects attending the optometry clinic. Videos were stored in a backup server through a secure file transfer protocol and analyzed by three different examiners: two masked observers (subjective evaluation) and a third investigator using the automatic software application (objective evaluation). Subjective evaluation was conducted only once on an online software designed for this protocol where videos were presented in random masked order. Automatic evaluation based on color and texture analysis was performed by (1) automatic localization of sequences of interest in the video, (2) extraction of the region of interest within each frame, and (3) automatic BUT measurement from evolution curves in the region of interest as time elapsed from the beginning of the sequence of interest until the curve exceeds a threshold. RESULTS: Substantial correlation was observed among the examiners (intraclass correlation coefficient, 0.752). There was a statistical difference between observer 1 and 2 evaluations (t test, P < .001), whereas data provided by the software showed no significant differences from those of the observers (t test, P ≥ .26). Similar results to the whole data set analysis were obtained when the sample was reassessed only considering mean BUT values ≤15 seconds. CONCLUSIONS: The present pilot study showed acceptable clinical results for the software application designed to objectively measure the BUT.

Accuracy of a Freezing Point Depression Technique Osmometer.

PURPOSE: The purpose of this study was to examine the precision and accuracy of the Fiske 110 Osmolarity System under different protocols to determine the possible applications of this device in tear film research and clinical practice. METHODS: Three separate studies were performed. In the first, Fiske 110 measurements were made on undiluted and diluted (1:1, 1:4, and 1:9 dilutions) standard samples of different osmolarity values: 50, 290, and 850 mOsm/kg and 297 and 338 mOsm/L. In the second study, measurements were made on different types of contact lens care solutions. Finally, in an agreement study, measurements were made in two sets of 60 subjects to compare TearLab versus Fiske 110 (using both 2- and 4-µL tear sample). RESULTS: Although osmolarity measurements for undiluted solutions differed statistically from reference standard values, all biases were in the tolerance range proposed by the manufacturer except for the 850-mOsm/kg solution. No significant differences from reference osmolarity values were observed for the 1:1 and 1:4 diluted 297- and 338-mOsm/L H2O solutions, respectively, although all diluted solutions showed a possible bias out of the range provided. Osmolarities for the soft contact lens solutions fell within the range 293 to 309 mOsm/kg with the exception of Opti-Free Express (225 mOsm/kg). In the agreement study, significant differences were observed between measurements obtained using the TearLab and both Fiske 110 procedures, although the Fiske 110 (4 µL) procedure was closer to the TearLab than the Fiske (2 µL) procedure. CONCLUSIONS: For undiluted solutions, the Fiske 110 shows good performance, making it a useful device for osmolarity measurements in lens care solutions or eye drops. A worse performance was observed for more diluted standard solution samples. When testing diluted samples, performance was acceptable for osmolarity values close to tear values.

Correlation between tear osmolarity and tear meniscus.

PURPOSE: To examine the relationship between tear meniscus height (TMH) and subjective meniscus grading (subjective tear meniscus [TM]) with tear osmolarity. METHODS: Tear osmolarity measurements (using TearLab) and digital images of the TM were obtained in 177 consecutive patients undergoing an eye examination at our optometry clinic (Universidad de Santiago de Compostela, Spain) who fulfilled the study's inclusion criteria. Participants were also administered the McMonnies and Ocular Surface Disease Index questionnaires for the detection of dry eye disease. The lower TM was videotaped by a digital camera attached to a slit lamp in its central portion without fluorescein instillation. After the study, a masked observer extracted an image from each video and measured the TMH using open source software (NIH ImageJ). Subsequently, the masked observer subjectively graded the appearance of each meniscus. For statistical analysis, subjects were stratified by age and by dry eye symptoms as indicated by their scores in the two questionnaires. RESULTS: In the whole study population, a significant relationship was observed between osmolarity and TMH (r = -0.41, p < 0.001) and osmolarity and subjective TM (r = 0.35, p < 0.001). A cluster analysis revealed similar correlations when subjects were stratified by age or dry eye symptoms, these correlations being more pronounced in older and more symptomatic subjects. Objective TMH measurements and subjective meniscus quality were also correlated (r = -0.75, p < 0.001). CONCLUSIONS: Osmolarity and both objective TMH measurements and subjective interpretation of the meniscus showed high correlation, especially in older symptomatic subjects.

Intraocular pressure fluctuations assessment in professional wind instrument players.

CLINICAL RELEVANCE: Due to the long-time that wind musicians spend playing their instruments, it is important to investigate if intraocular pressure could be affected by this activity. BACKGROUND: To assess the intraocular pressure fluctuations and fluctuations affecting factors in professional wind musicians while playing different tones. METHODS: Thirty professional wind musicians (23.0 ± 3.20 years) were recruited from the Professional Music College of A Coruña. A questionnaire about environmental/demographic factors was given to participants. Intraocular pressure was measured four times by ICare IC100 tonometer: before, during low and high-pitched tones, and immediately after stopping playing the wind instrument. RESULTS: Pairwise comparison revealed statistical differences between measurement points (Sidak, all p ≤ 0.019), except between before playing and while playing low-pitched tones (Sidak, p = 1.000). Intraocular pressure increases during high pitch playing and decreases after stopping playing. No significant differences in intraocular pressure fluctuation were reported between physically active (>2 days/week) and non-physically active participants (Unpaired t-test, p = 0.680). All intraocular pressure values were positively correlated (Pearson's correlation, all r ≥ 0.505, p ≤ 0.004). Intraocular pressure fluctuations were negatively correlated with musical playing years (Pearson's correlation, r = - 0.396, p = 0.030). There were no significant correlations among intraocular pressure fluctuation and gender, age, weight, height, or daily time playing (Pearson's correlation, all p ≥ 0.058). CONCLUSION: Professional wind musicians suffer intraocular pressure peaks while playing high-pitched tones; therefore, ocular fundus evaluation and visual campimetry should be performed as routine tests in the visual exam of this population.

A Comprehensive Study on Tear Meniscus Height Inter-Eye Differences in Aqueous Deficient Dry Eye Diagnosis.

(1) Background: Dry eye disease (DED) is a chronic ocular surface condition that requires precise diagnostic tools. The present study aimed to investigate the diagnostic potential of the absolute inter-eye difference (|OD-OS|) in tear meniscus height (TMH) for the detection of the presence of aqueous deficient dry eye (ADDE). (2) Methods: A sample of 260 participants with dry eye complaints underwent ocular surface examinations thorough diagnostic assessments based on the Tear Film and Ocular Surface Society guidelines (TFOS DEWS II). Participants were subsequently categorized as No ADDE and ADDE based on TMH. Statistical analyses to determine the optimal TMH|OD-OS| cut-off value in a randomly selected study group (200 participants) were performed, while a separate validation analysis of the cut-off value obtained in a random cross-validation group (60 participants) was also performed. (3) Results: The significant diagnostic capability of TMH|OD-OS| (area under the curve = 0.719 ± 0.036, p < 0.001) was found. The identified cut-off value of 0.033 mm demonstrated reliable specificity (77.6%) and moderate sensitivity (59.1%). Cross-validation confirmed the cut-off value's association with the TFOS DEWS II diagnostic criterion (Cramer's V = 0.354, p = 0.006). (4) Conclusions: The present study provides evidence for the diagnostic potential of TMH|OD-OS| in identifying ADDE. The identified cut-off value enhances the specificity and offers moderate sensitivity, providing an objective tool for clinical decision making.

Temporal Variations in Convergence Insufficiency Symptomatic Status among University Students before and after COVID-19: A Longitudinal Analysis from 2018 to 2023.

The present study aimed to assess the symptomatic status of Convergence Insufficiency (CI) in university students from 2018 to 2023 considering the educational environment pre- and post-COVID-19 pandemic confinements. A Convergence Insufficiency Symptom Survey (CISS) was conducted annually from 2018 to 2023, excluding 2020, in an initial group of 217 third-year Optics and Optometry degree university student participants. In the final group (178 participants), the statistical differences in CISS scores between years were analysed, both overall and by questionnaire subgroup, along with associations between CISS diagnostic categories before and after 2020. Significant differences were found between years in the subscale and total score analyses (Kruskal-Wallis, both p ≤ 0.049). Pairwise comparisons showed significant differences for the performance subgroup in 2021 vs. 2019 and 2018 (Mann-Whitney, both p ≤ 0.004), while in terms of the total score, there was a statistical difference in 2021 vs. 2018 (Mann-Whitney, p < 0.001). The distribution analysis indicated a significant difference between groups (Chi, p = 0.004), with participants from 2021 or later more likely to exhibit higher CISS scores (OR = 3.47, 95%CI 1.04-8.58). The present study shows significant temporal increments in symptomatic status related to CI among university students from 2018 to 2023, indicating a potential impact of the COVID-19 pandemic educational landscape on these outcomes.

Temporal Progression of Entry Factors into the Vicious Circle of Dry Eye in Untreated Sufferers.

BACKGROUND: Dry eye disease (DED) is characterized by the loss of ocular surface homeostasis with specific signs and symptoms. Studying the progression of a multifactorial disease is exceedingly challenging for researchers because several factors can influence it. The present study aims to study changes in tear meniscus height (TMH), lipid layer pattern (LLP), and bulbar hyperemia over time in untreated DED participants. METHODS: This retrospective longitudinal study included 73 participants (146 eyes) diagnosed with DED since at least 2013. Participants underwent new examinations between 2021 and 2023, grouped by 8-, 6-, or 4-year follow-up periods. TMH, LLP, and bulbar hyperemia were assessed in both examinations. No participant received pharmacological treatment for DED. RESULTS: Differences in TMH, bulbar hyperemia, and LLP between sessions were obtained in the 8-year group (p ≤ 0.027). Differences in bulbar hyperemia and LLP between sessions were obtained in the 6-year group (p ≤ 0.022). The only differences in LLP between sessions were obtained in the 4-year group (p < 0.005). CONCLUSION: Changes in TMH were obtained after periods of eight years from the first eye examination. Also, changes in bulbar hyperemia were obtained at periods of 8 and 6 years; however, changes in LLP could be found from 4-year follow-ups.

Capability of the Inter-Eye Differences in Osmolarity, Break-Up Time and Corneal Staining on the Diagnostic of Dry Eye.

PURPOSE: Inter-eye variability is a recognized characteristic of Dry Eye Disease (DED) and has been proposed as a diagnostic indicator in clinical practice. This study aimed to assess the diagnostic potential of the absolute difference between eyes in three key diagnostic tests recommended by the Tear Film and Ocular Surface Society Dry Eye Workshop II (TFOS DEWS II) Diagnostic Methodology report: tear film osmolarity, Fluorescein Break-Up Time (FBUT), and ocular surface staining. METHODS: A total of 180 participants were included in a cross-sectional study. Before a dry eye examination, participants completed an online self-administered OSDI questionnaire. The TFOS DEWS II diagnostic criteria for DED assessment were used: along with OSDI, osmolarity, FBUT and ocular surface staining were measured in all participants in both eyes following standardized methodology. Based on signs and symptoms, participants were diagnosed as having No DED or DED. After diagnosis, the parameters were computed as the right and left eyes' absolute inter-eye difference (|OD-OS|). RESULTS: Receiver Operating Characteristics analyses for computed parameters were used based on the previous diagnosis. ROC analyses showed that Osmolarity|OD-OS| have a diagnostic capability to differentiate between No DED and DED participants with a cut-off value of 9.5 mOsm/L (AUC = 0.745 ± 0.052, p < 0.003), whereas FBUT|OD-OS| and Corneal Stainning|OD-OS| have not (AUC, both p ≥ 0.160). CONCLUSION: The present study found that the Osmolarity|OD-OS| parameter could be used as a diagnostic indicator for DED assessment, while the FBUT|OD-OS| and the Corneal Staining|OD-OS| parameters do not have this capability.

Analysis of the Differences in Ocular Surface Damage and Inflammatory Signs between Healthy and Evaporative Dry Eye Participants.

OBJECTIVE: Distinguish between EDE severity levels by analysing the MGLA, conjunctival hyperemia and corneal staining. METHODS: One hundred participants were recruited based on OSDI, TO, TFBUT, TMH, and LLP to be categorised as healthy (Group 1) or EDE (Group 2). Group 2 was divided into Group 2A (mild symptoms), 2B (moderate), and 2C (severe). MGLA, conjunctival hyperemia, and corneal staining were measured. RESULTS:  Positive correlation between MGLA, conjunctival hyperemia, and corneal staining were found (all r ≥ 0.221, p ≤ 0.027). Significant differences were found: MGLA between Group 1 vs. 2C and 2C vs. 2A or 2B; conjunctival hyperemia between Group 1 vs. 2A, 2B or 2C; corneal staining between Group 1 vs. 2B or 2C and 2A vs. 2B or 2C (all p ≤ 0.049). CONCLUSION: Severe EDE participants have higher MGLA, conjunctival hyperemia, and corneal staining values than healthy, mild, or moderate EDE participants.

Diurnal variations of tear film osmolarity on the ocular surface.

The measurement of tear film osmolarity has been suggested as a gold standard in the diagnosis of dry eye. Many tear film physiological variables oscillate during the day. This review summarises current clinical knowledge regarding diurnal osmolarity variation in the tear film. A critical analysis is presented in respect of of sample size and characteristics, differences in the diurnal osmolarity variation on healthy versus altered tear film conditions or environment, and time of day and number of measurements undertaken. A comparison of 21 studies was made for studies in which one of the main objectives was to analyse the variance of tear film osmolarity at different time-points in a day on human cohorts. Tear film osmolarity appeard to be somewhat influenced by the time of day in healthy subjects and patients with ocular surface disease, or altered by environmental conditions. Both healthy and non-physiological tear film cohorts showed variations in results depending on the study: no variations during the day or statistically different values at some point in the day. These differences could be in the middle of the day or between the beginning and the end of the day, with higher values in the morning than in the afternoon, or even the opposite situation. The possibility of diurnal variations in tear film osmolarity should be considered by the clinician since the time of day when the tear film measurements are made can be critical in making the right diagnosis. Future studies in the diurnal variation field may have to use a well-established range of measurement time-points and a larger group of healthy subjects and and subjects who have a tear film altered by pathological or environmental conditions.

A cross-sectional study of non-modifiable and modifiable risk factors of dry eye disease states.

PURPOSE: The present study aimed to determine the relationship of non-modifiable (rheumatoid arthritis, thyroid diseases, and arterial hypertension) and modifiable risk factors (diuretics, antidepressants, or anxiolytics tranquilizers) with the different Dry Eye Disease (DED) diagnostics in a sample adjusted by antihistamines intake. METHODS: A total of 400 participants were included in a cross-sectional study. Before a dry eye examination, participants completed an online self-administered OSDI questionnaire with six additional questions about possible DED risk factors. The Tear Film and Ocular Surface Society Dry Eye Workshop II (TFOS DEWS-II) diagnostic criteria of DED was used. Based on signs and/or symptoms, participants were divided into 4 groups: No DED, Pre-clinical DED, Predisposition to DED and DED. Since the symptom scores would have been altered by the use of antihistamines, the analysis of each outcome was adjusted for this factor, where those participants were assumed to be symptomatic. RESULTS: Multivariable logistic regression found thyroid disease as a possible risk factor for DED (OR 4.53, 95 % CI 1.04-19.73; Fisher's exact, p = 0.044; Cramers V = 0.140, p = 0.024). No association was found between the studied parameters and Pre-clinical DED (Fisher's exact, all p ≥ 0.398; Cramers V, all p ≥ 0.242) or Predisposition to DED (Fisher's exact, all p ≥ 0.065; Cramers V, all p ≥ 0.031). CONCLUSION: Participants with thyroid disease were more likely to develop DED, therefore, thyroid disease could be a risk factor for DED.

Lenstar LS900 vs EchoScan US-800: comparison between optical and ultrasound biometry with and without contact lenses and its relationship with other biometric parameters.

BACKGROUND: Due to the increasing use of contact lenses (CL) and the interest in ocular and body size relationships, this study aimed to compare measurements from two biometers (contact ultrasonic EchoScan US-800 and non-contact optical Lenstar LS900) with and without CL and to explore the relationship between ocular and body biometric parameters. DESIGN AND METHODS: This cross-sectional study measured ocular biometry using two biometers along with their body height and right foot length in 50 participants. Differences between biometry data from the two devices were compared and correlations between ocular and body biometric values were analyzed. RESULTS: All parameters showed interbiometric differences (p ≤ 0.030), except crystalline lens thickness during CL wear (p = 0.159). Comparing measurements with and without CL, differences were observed in axial length (p < 0.001), vitreous length measured by optical biometer (p = 0.016), and anterior chamber depth by ultrasonic biometer (p < 0.016). Lens thickness remained unaffected (p ≥ 0.190). Body height and foot length were correlated with anterior chamber depth, vitreous length, and axial length (p ≤ 0.019, r ≥ 0.330). Most biometric parameters were correlated among them using both devices (p ≤ 0.037, r ≥ 0.296). CONCLUSIONS: These biometers are not interchangeable and CL affects measurements. Body height and foot length correlate with ocular dimensions, and most ocular biometric values correlate positively.

Intraocular Pressure Fluctuation Throughout the Day.

Purpose To compare intraocular pressure (IOP) values at different time points, both in the total sample and according to iridocorneal angle aperture, to assess whether IOP fluctuations were constant throughout the day, and to examine correlations with other factors. Methods Over a single day, the IOP of 34 volunteers was measured at three-hour intervals from 9:00 a.m. to 6:00 p.m. To avoid any IOP value being affected by other measurements, anamnesis, slit-lamp evaluation (with iridocorneal angle measurement), and refractive status were performed after the final measurement. The differences between IOP values at different time points and IOP fluctuation at three-hour intervals were compared by ANOVA and Friedman test, respectively, both for the total group and according to iridocorneal angle aperture. For relationships, Pearson's correlation was performed for parametric variables and Spearman's correlation for nonparametric variables. Results Significant differences were observed in IOP between time points for the total sample (p < 0.001), but not for a narrow-angle group (p = 0.058). No significant differences were found in IOP fluctuations at three-hour intervals either in the total sample or according to angle aperture (all p ≥ 0.332). There was a positive correlation of IOP at different time points (all r ≥ 0.646, all p < 0.001) but no relationship with spherical equivalent, age, or sleep duration (all p ≥ 0.057). IOP at 12:00 p.m. was correlated with a 12:00 p.m. to 3:00 p.m. fluctuation (r = 0.428, p = 0.012); and IOP fluctuation between 9:00 a.m. and 12:00 p.m. was correlated with age (r = 0.485, p = 0.004). Conclusion As IOP decreases from morning until at least 6:00 p.m., measuring these two values during clinical evaluation is essential for the effective monitoring and prevention of IOP-related diseases.

Cysteamine Eye Drops in Hyaluronic Acid Packaged in Innovative Single-Dose Systems, Part II: Long-Term Stability and Clinical Ocular Biopermanence.

BACKGROUND: Cystinosis is a rare genetic disorder characterized by the accumulation of cystine crystals in several tissues and organs causing, among others, severe eye symptoms. The high instability of cysteamine eye drops makes it difficult to develop formulations with an acceptable shelf life to be prepared in hospital pharmacy departments. Previously, a new compounded formulation of cysteamine eye drops in hyaluronic acid (HA) packaged in innovative single-dose systems was developed. METHODS: Long-term stability at -20 °C of this formulation was studied considering the content of cysteamine, pH, osmolality, viscosity, and microbiological analysis. The oxygen permeability of single-dose containers was also studied and an ocular biopermanence study was conducted in healthy volunteers measuring lacrimal stability and volume parameters. RESULTS: Data confirm that cysteamine concentration remained above 90% for 120 days, all parameters remaining within the accepted range for ophthalmic formulations. The permeability of the containers was reduced over time, while ocular biopermanence was maintained despite the freezing process and storage time. CONCLUSIONS: 0.55% cysteamine hydrochloride formulation in HA and packaged in single-dose containers preserved at -20 °C is stable for 120 days protected from light, presenting high potential for its translation into clinical practice when commercial presentations are not available.

Accuracy and repeatability of a new tono-pachymeter for measuring central corneal thickness.

OBJECTIVES: The recently developed noncontact tonopachymeter Tonopachy NT-530 P provides intraocular pressure values corrected for central corneal thickness (CCT). The purpose of this study was to assess the accuracy and repeatability of its CCT measurements. METHODS: The CCT measurements were obtained in 64 right eyes of 64 young healthy subjects using the Orbscan corneal topography system followed by the Tonopachy and then by ultrasound pachymetry (UP). Another sample of 31 subjects was used to test the repeatability of the tonopachy measurements in 2 separate sessions 1 week apart. To compare the tonometers and determine intersession repeatability for the tonopachymeter, differences in the readings provided by pairs of the instruments or obtained in the two sessions were plotted against mean differences. The hypothesis of zero bias was examined by a paired t-test. The coefficient of repeatability was calculated as the 95% limits of agreement (LoAs) of differences between the 2 sessions. RESULTS: Measurements made using the three instruments were significantly correlated (P<0.001). Mean CCTs (±SD) measured using the Tonopachy, Orbscan (acoustic factor set at 0.92) and ultrasound pachymeter were 530.42 ± 34.96, 526.73 ± 39.53, and 550.69 ± 37.26 µm, respectively. The differences between modalities (±95% LoAs) were -3.68 ± 24.36 for Orbscan versus Tonopachy, 20.66 ± 14.69 for UP versus Tonopachy, and 23.95 ± 24.21 for UP versus Orbscan. The coefficient of repeatability for the tonopachymeter was ±15.11 µm. CONCLUSIONS: The Tonopachy offers similar CCT measurements to those provided by conventional pachymeters with good repeatability.