Effects of Preservative-free 3% Diquafosol in Patients with Pre-existing Dry Eye Disease after Cataract Surgery: A Randomized Clinical Trial

Dry eye disease (DED) after cataract surgery has become a critical concern, and various therapeutic options have been developed. Recently, preservative-free diquafosol ophthalmic solution has been introduced; however, its therapeutic effect on DED after cataract surgery has not been reported. We investigated the efficacy of preservative-free diquafosol in patients with pre-existing DED after cataract surgery. We divided subjects who were diagnosed with DED and scheduled to undergo cataract surgery, into 3 groups (preservative-free diquafosol, group 1; preservative-containing diquafosol, group 2; preservative-free hyaluronate, group 3), and each eye drops was administered 6 times daily after surgery. Tear break up time (TBUT), Ocular Surface Disease Index (OSDI), corneal staining score, lid margin abnormality, and meibum quality improved over time in group 1. Groups 1 and 2 had significantly superior TBUT, meibomian gland dysfunction grade, and meibomian gland expressibility throughout the study period than group 3. Meibum quality of group 1 was significantly better than group 2 at 1 and 3 months after surgery. Preservative-free diquafosol showed better efficacy in treating DED after cataract surgery than preservative-containing diquafosol or preservative-free hyaluronate. Preservative-free diquafosol may serve as a reliable option for the management of patients with pre-existing DED after phacoemulsification.ope

Prediction accuracy of conventional and total keratometry for intraocular lens power calculation in femtosecond laser-assisted cataract surgery

This study evaluated the accuracy of total keratometry (TK) and standard keratometry (K) for intraocular lens (IOL) power calculation in eyes treated with femtosecond laser-assisted cataract surgery. The retrospective study included a retrospective analysis of data from 62 patients (91 eyes) who underwent uneventful femtosecond laser-assisted cataract surgery with Artis PL E (Cristalens Industrie, Lannion, France) IOL implantation by a single surgeon between May 2020 and December 2020 in Severance Hospital, Seoul, South Korea. The new IOLMaster 700 biometry device (Carl Zeiss Meditec, Jena, Germany) was used to calculate TK and K. The mean absolute error (MAE), median absolute error (MedAE), and the percentages of eyes within prediction errors of ± 0.25 D, ± 0.50 D, and ± 1.00 D were calculated for all IOL formulas (SRK/T, Hoffer-Q, Haigis, Holladay 1, Holladay 2, and Barrett Universal II). There was strong agreement between K and TK (intraclass correlation coefficient = 0.99), with a mean difference of 0.04 D. For all formulas, MAE tended to be lower for TK than for K, and relatively lower MAE and MedAE values were observed for SRK/T and Holladay 1. Furthermore, for all formulas, a greater proportion of eyes fell within ± 0.25 D of the predicted postoperative spherical equivalent range in the TK group than in the K group. However, differences in MAEs, MedAEs, and percentages of eyes within the above prediction errors were not statistically significant. In conclusion, TK and K exhibit comparable performance for refractive prediction in eyes undergoing femtosecond laser-assisted cataract surgery.ope

Comparison of Anterior Segment Measurements with a New Multifunctional Unit and Five Other Devices

Purpose: To evaluate the clinical availability of a multifunctional ocular biometric unit, MR-6000, for simultaneous keratometry, tonometry, topography, and pachymetry evaluation, and compare anterior segment measurements with five other devices: autokeratometer (KR-1), Scheimpflug camera (Pentacam HR), swept-source optical coherence tomography (IOLMaster 700), Placido disk scanning-slit topography (Orbscan II), and noncontact tonometry (FT-1000). Methods: Thirty eyes from thirty patients who visited Severance Hospital for cataract surgery were examined using MR6000 and the other devices. The mean keratometry, central corneal thickness (CCT), white-to-white (WTW) distance, and intraocular pressure (IOP) values were compared. Repeated measures analysis of variance, Wilcoxon signed-rank test, intraclass correlation coefficient (ICC), and Bland-Altman plot were used to assess the correlation and agreement between devices. Results: Thirty eyes of thirty patients were evaluated. Statistically significant differences in mean keratometry between MR6000, KR-1, Pentacam HR, and IOLMaster 700 were not observed (p > 0.05). All five devices, including Orbscan II, had almost perfect agreement in measuring keratometry (ICC > 0.80, p 0.60, p < 0.05). The WTW distance measured by MR-6000 was not significantly different from that measured by IOLMaster 700 but was different from that measured by Orbscan II. IOP measured by MR-6000 was not correlated with FT-1000. Conclusions: Keratometric values obtained through MR-6000 can be used interchangeably with other devices based on good correlation and agreement. However, the CCT, WTW, and IOP values were not interchangeable with a single multifunctional unit for cataract surgery preoperative examination.ope

음이온채널에서의 이온선택성 동적 변화의 기전

Dept. of Medical Science/박사Ion permeation through anion channels plays essential roles in our body. However, how the anion channels retain ion selectivity and how the anion selectivity is regulated are largely unknown. Here, I show that the combined effects of thermodynamic hydration energy and size-exclusion force of the pore determine the anion selectivity. The dielectric constant increase and pore size enlargement are found when WNK1/SPAK associated HCO3− permeability increase happens in CFTR. In ANO1/TMEM16A channel, this finding is also found during HCO3− permeability change due to high intracellular calcium concentration. In GlyR, P-2’Δ mutation caused the pore dilation, HCO3− permeability change, and electric permittivity rise. Molecular dynamic simulation showed that pore dilation not only affected the energy barriers of size exclusion but that of ion dehydration by altering water occupancy in the channel filter region. Application of high dose GABA dynamically modulated anion selectivity of GABAAR, which is essential for GABA induced action potential generation in pyramidal neuron of sensorimotor cortex. New anion selectivity modeling was performed by integration of thermodynamic hydration energy and size-exclusion force of the pore. Importantly cellular stimuli dynamically modulated anion selectivity by changing pore size, and a finding that is common to all anion channels studied, including CFTR, ANO1/TMEM16A, GlyR, and GABAAR, is that pore dilation increases PHCO3/PCl by affecting energy barriers of size exclusion and ion dehydration of HCO3− permeation. I also provide evidence and suggest that the dynamic increase in PHCO3/PCl is involved in many physiological and pathophysiological processes, such as CFTR-mediated epithelial HCO3− secretion and GABAAR-evoked neuronal excitation. 음이온채널을 통한 이온의 수송은 우리 몸에서 아주 중요한 역할을 하고 있다. 하지만 음이온 채널이 이온선택성을 어떻게 유지하고 또한 어떤 기전에 의해 조절되는 지에 대한 연구는 많이 부족하다. 따라서 본 연구를 통해 열역학적 수화 에너지와 이온의 크기에 따른 선별력이 동시에 작용하여 음이온통로의 이온선택성을 결정할 수 있는 것을 확인 하였다. WNK1/SPAK 인산화 효소에 의한 CFTR의 중탄산염 투과도 증가가 일어날 때 유전상수의 증가와 이온 통로의 확장이 동시에 발생한다. 또한 ANO1/TMEM16A 에서도 세포 내 고농도 칼슘에 의한 중탄산염 투과도 증가가 발생할 때 같은 현상이 일어남을 확인 하였다. 글리신 수용체의 프롤린-2’ 결손 돌연변이가 이온 통로의 확장, 중탄산염 투과도 증가, 유전율의 상승을 유발한다. 분자동역학적 모의실험을 통하여 이온 통로의 확장이 이온 크기에 따른 선별력 뿐 아니라 이온 채널 내부의 이온의 선택성 결정 심사부위의 물 분자 점유량을 높여 이온의 탈수화 에너지를 동시에 조절하는 것을 확인 하였다. 가바 수용체에 고농도의 가바를 적용하였을 때 음이온 선택성이 동적으로 조절되고, 이러한 현상은 감각 운동 피질의 피라미드 뉴런에서 가바에 의한 활성 전위 생성에 필수적인 요소임이 확인 되었다. 이러한 열역학적 수화에너지와 이온 크기에 따른 선별력을 종합하여 새로운 음이온 선택성 모형화를 시행하였다. 특히 세포 내 자극을 통해 이온선택성이 동적으로 조절되는데 있어 이온 통로의 구멍 크기가 변화하는 것이 중요하다는 것을 밝혔다. CFTR, ANO1/TMEM16A, 글리신 수용체, 가바 수용체 같은 다양한 이온 채널에서 이온 통로 크기의 증가로 인해 중탄산염의 투과도가 증가하는 현성을 발견하였는데 이것은 이온 크기에 따른 선별 및 이온의 수화에너지를 조절하여 일어남을 규명하였다. 또한 이러한 중탄산염의 동적인 투과도 증가가 CFTR을 통한 중탄산염의 분비나 가바수용체를 통한 신경 활성등의 많은 생리학적 그리고 병태생리학적인 과정에 관련이 있다는 것에 대한 증거를 제시하였다.ope

Phenotypes of Granular Corneal Dystrophy Type 2 among Koreans in Their Twenties

Purpose Granular corneal dystrophy type 2 (GCD2) is a hereditary disease that features granular and lattice stromal deposits in the cornea. There are homozygotes and heterozygotes and the opacities are exacerbated by corneal trauma or surgery, such as laser in situ keratomileusis (LASIK). As there is individual variability in GCD2 phenotypes, we investigated various corneal features of GCD2 patients in their twenties, the main age group for refractive surgery. Methods From genetically confirmed GCD2 patients who had an R124H mutation of the transforming growth factor β induced (TGFBI) gene at age 20 to 29 years, we chose representative patients: one homozygote; one compound heterozygote; one simple heterozygote with a severe phenotype with many granular deposits; one common heterozygote; and four heterozygotes with normal corneas. The corneas of all patients were subject to slit-lamp examination and photographed. Results The homozygote had confluent granular deposits covering the cornea. The compound heterozygote had granular and lattice deposits covering the center of the cornea. The patient with a severe phenotype had more than 30 granular deposits in one eye, but was a simple GCD2 heterozygote, verified by full-sequencing of the TGFBI gene. In the four patients with normal corneas, a single small lesion was subsequently detected during follow-up in two, at 3 weeks and 6 months, respectively. Both corneas were judged clear at chance examinations. Conclusions Among Koreans in their twenties, GCD2 patients have various phenotypes, from clear corneas to severe confluent opacities. There are GCD2 heterozygotes with nearly clear corneas, so caution must be taken when choosing patients for refractive surgery.ope

Isorhamnetin Ameliorates Dry Eye Disease via CFTR Activation in Mice

Dry eye disease is one of the most common diseases, with increasing prevalence in many countries, but treatment options are limited. Cystic fibrosis transmembrane conductance regulator (CFTR) is a major ion channel that facilitates fluid secretion in ocular surface epithelium and is a potential target of therapeutic agent for the treatment of dry eye disease. In this study, we performed a cell-based, high-throughput screening for the identification of novel natural products that activate CFTR and restore the aqueous deficiency in dry eye. Screening of 1000 natural products revealed isorhamnetin, a flavonol aglycone, as a novel CFTR activator. Electrophysiological studies showed that isorhamnetin significantly increased CFTR chloride current, both wild type and ∆F508-CFTR. Isorhamnetin did not alter intracellular cAMP levels and the activity of other ion channels, including ANO1, ENaC, and hERG. Notably, application of isorhamnetin on mouse ocular surface induced CFTR activation and increased tear volume. In addition, isorhamnetin significantly reduced ocular surface damage and expression of interleukin (IL)-1β, IL-8, and tumor necrosis factor (TNF)-α in an experimental mouse model of dry eye. These data suggest that isorhamnetin may be used to treat dry eye disease.ope

Temperature-dependent increase in the calcium sensitivity and acceleration of activation of ANO6 chloride channel variants

Anoctamin-6 (ANO6) belongs to a family of calcium (Ca2+)-activated chloride channels (CaCCs), with three splicing variants (V1, V2, and V5) showing plasma membrane expression. Unlike other CaCCs, ANO6 requires a non-physiological intracellular free calcium concentration ([Ca2+]i > 1 μM) and several minutes for full activation under a whole-cell patch clamp. Therefore, its physiological role as an ion channel is uncertain and it is more commonly considered a Ca2+-dependent phospholipid scramblase. Here, we demonstrate that physiological temperature (37 °C) increases ANO6 Ca2+ sensitivity under a whole-cell patch clamp; V1 was activated by 1 μM [Ca2+]i, whereas V2 and V5 were activated by 300 nM [Ca2+]i. Increasing the temperature to 42 °C led to activation of all ANO6 variants by 100 nM [Ca2+]i. The delay time for activation of the three variants was significantly shortened at 37 °C. Notably, the temperature-dependent Ca2+-sensitisation of ANO6 became insignificant under inside-out patch clamp, suggesting critical roles of unknown cytosolic factors. Unlike channel activity, 27 °C but not 37 °C (physiological temperature) induced the scramblase activity of ANO6 at submicromolar [Ca2+]i (300 nM), irrespective of variant type. Our results reveal a physiological ion conducting property of ANO6 at 37 °C and suggest that ANO6 channel function acts separately from its scramblase activity.ope

Novel CFTR Activator Cact-3 Ameliorates Ocular Surface Dysfunctions in Scopolamine-Induced Dry Eye Mice

Cystic fibrosis transmembrane conductance regulator (CFTR) is highly expressed on the ocular epithelium and plays a pivotal role in the fluid secretion driven by chloride transport. Dry eye disease is one of the most common diseases with limited therapeutic options. In this study, a high-throughput screening was performed to identify novel CFTR activators capable of inducing chloride secretion on the ocular surface. The screening of 50,000 small molecules revealed three novel CFTR activators. Among them, the most potent CFTR activator, Cact-3 (7-(3,4-dimethoxyphenyl)-N-(4-ethoxyphenyl)pyrazolo [1,5-α]pyrimidine-2-carboxamide), produced large and sustained Cl- currents in WT-CFTR-expressing FRT cells with no alterations of ANO1 and hERG channel activity. The application of Cact-3 strongly activated CFTR in the ocular epithelia of mice and it also significantly increased CFTR-mediated Cl- transport in a primary cultured human conjunctival epithelium. Cact-3 strongly stimulated tear secretion in normal mice. In addition, Cact-3 significantly reduced ocular surface damage and the expression of proinflammatory factors, including interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ in an experimental mouse model of dry eye disease. These results suggest that Cact-3, a novel CFTR activator, may be a potential development candidate for the treatment of dry eye disease.ope

Patient selection for corneal topographic evaluation of keratoconus: A screening approach using artificial intelligence

Background: Corneal topography is a clinically validated examination method for keratoconus. However, there is no clear guideline regarding patient selection for corneal topography. We developed and validated a novel artificial intelligence (AI) model to identify patients who would benefit from corneal topography based on basic ophthalmologic examinations, including a survey of visual impairment, best-corrected visual acuity (BCVA) measurement, intraocular pressure (IOP) measurement, and autokeratometry. Methods: A total of five AI models (three individual models with fully connected neural network including the XGBoost, and the TabNet models, and two ensemble models with hard and soft voting methods) were trained and validated. We used three datasets collected from the records of 2,613 patients' basic ophthalmologic examinations from two institutions to train and validate the AI models. We trained the AI models using a dataset from a third medical institution to determine whether corneal topography was needed to detect keratoconus. Finally, prospective intra-validation dataset (internal test dataset) and extra-validation dataset from a different medical institution (external test dataset) were used to assess the performance of the AI models. Results: The ensemble model with soft voting method outperformed all other AI models in sensitivity when predicting which patients needed corneal topography (90.5% in internal test dataset and 96.4% in external test dataset). In the error analysis, most of the predicting error occurred within the range of the subclinical keratoconus and the suspicious D-score in the Belin-Ambrósio enhanced ectasia display. In the feature importance analysis, out of 18 features, IOP was the highest ranked feature when comparing the average value of the relative attributions of three individual AI models, followed by the difference in the value of mean corneal power. Conclusion: An AI model using the results of basic ophthalmologic examination has the potential to recommend corneal topography for keratoconus. In this AI algorithm, IOP and the difference between the two eyes, which may be undervalued clinical information, were important factors in the success of the AI model, and may be worth further reviewing in research and clinical practice for keratoconus screening.ope

Activation of ADRB2/PKA Signaling Pathway Facilitates Lipid Synthesis in Meibocytes, and Beta-Blocker Glaucoma Drug Impedes PKA-Induced Lipid Synthesis by Inhibiting ADRB2

Meibomian gland dysfunction is one of the main causes of dry eye disease and has limited therapeutic options. In this study, we investigated the biological function of the beta 2-adrenergic receptor (ADRB2)/protein kinase A (PKA) pathway in lipid synthesis and its underlying mechanisms in human meibomian gland epithelial cells (HMGECs). HMGECs were cultured in differentiation media with or without forskolin (an activator of adenylate cyclase), salbutamol (an ADRB2 agonist), or timolol (an ADRB2 antagonist) for up to 4 days. The phosphorylation of the cAMP-response element-binding protein (CREB) and the expression of peroxisome proliferator activator receptor (PPAR)γ and sterol regulatory element-binding protein (SREBP)-1 were measured by immunoblotting and quantitative PCR. Lipid synthesis was examined by LipidTOX immunostaining, AdipoRed assay, and Oil Red O staining. PKA pathway activation enhanced PPARγ expression and lipid synthesis in differentiated HMGECs. When treated with agonists of ADBR2 (upstream of the PKA signaling system), PPARγ expression and lipid synthesis were enhanced in HMGECs. The ADRB2 antagonist timolol showed the opposite effect. The activation of the ADRB2/PKA signaling pathway enhances lipid synthesis in HMGECs. These results provide a potential mechanism and therapeutic target for meibomian gland dysfunction, particularly in cases induced by beta-blocker glaucoma drugs.ope