Objective quantification of fluorescence intensity on the corneal surface using a modified slit-lamp technique.

ObjectivesTo improve the digital quantification of fluorescence intensity of sodium fluorescein instilled on corneal surface by modifying a slit lamp hardware and performing computerized processing of captured digital images.MethodsThe optics of a slit lamp were modified to remove corneal Purkinje reflection and to expand the illuminated area on the cornea, followed by postexperiment image processing to minimize the influence of uneven illumination. To demonstrate the feasibility and reliability of this new technique, we applied it to objective grading of corneal staining with sodium fluorescein. The results of computerized grading were compared with the results obtained using standard subjective grading of corneal staining. Objective digital grades, staining area, and staining pixel with manually and automatically defined threshold (SP-M and SP-A) were calculated for both original and processed images. Standard subjective grades of the original images were performed by 13 trained observers using National Eye Institute (NEI), Efron, and CCLRU grading scales. A series of linear regression analyses were performed to investigate the correlation between objective and subjective grades.ResultsDigital grades of the captured images were correlated significantly with subjective grades. After minimization of the artifact caused by the nonuniform illumination, correlations between digital and subjective grading were mostly strengthened. In some cases, digital grading of corneal staining was more sensitive than subjective grading methods when differentiating subtle differences of corneal staining.ConclusionsModifications performed on commercial slit-lamp hardware and the proposed digital image-processing technique have improved the quality of captured images for semiautomated quantification of fluorescein intensity on the cornea

Effects of corneoscleral topography on soft contact lens performance: A pilot study.

To quantify corneoscleral junction (CSJ) topography in soft contact lens (SCL) wearers, and assess the association between the CSJ and SCL performance and subjective comfort, forty-four adapted SCL wearers (16 Asians, 16 Caucasians, 12 Latinos) were recruited for the present study. Corneal topography was taken with a Medmont E300 (Medmont International, Pty Ltd.). CSJ images were taken with a commercial OCT (Bioptigen, Inc.). Our published CSJ image analysis technique was used to describe the geometric properties of the CSJ using the sum of squared orthogonalized residuals (SSRo). Multivariable mixed effects models were employed to examine associations between SSRo and subject demographics, ocular characteristics, SCL fit and performance, and comfort. The SSRo was significantly related to quadrant (p < 0.001), ethnicity (p = 0.014), and horizontal corneal shape factor (p = 0.044). The nasal quadrant had the largest SSRo, indicating the steepest CSJ profile and/or the most irregular CSJ surface, followed by the inferior quadrant. The superior and temporal quadrants had the smallest SSRo, indicating relatively flat and even CSJ topography. Caucasians had the steepest and/or most irregular CSJ compared with Latinos and Asians. Less inferior-superior heterogeneity in the SSRo was associated with greater comfort after 6 h of lens wear. The SSRo was proved to be a useful tool to quantify CSJ geometry in SCL wearers. Significant differences in the SSRo were found among quadrants and ethnic groups. Better subjective comfort after 6 h of SCL wear was associated with a smaller difference in the SSRo between the superior and inferior quadrants

Effects of scleral-lens oxygen transmissibility on corneal thickness: A pilot study.

PurposeTo investigate the effect of various oxygen transmissibilities (Dk/t) of scleral lenses and corneal thickness recovery time from overnight eye closure with patching on corneal edema during 5 h lens wear.MethodsScleral lenses (hofocon A, 15.6 mm diameter) were worn bilaterally with three different Dks (100, 140, and 160 Barrer). Central and peripheral corneal thickness (CCT and PCT) were measured using optical coherence tomography. Four subjects were randomly selected for one additional visit and asked to patch one eye before night sleeping. The patch was not removed until lens insertion to avoid corneal deswelling. Then CCT of both eyes was measured.ResultsTen neophytes with healthy eyes participated in the study. Mean [95% CI] Dk/t of the study lenses was 32.0 [29.2, 34.7] hBarrer/cm. Mean [95% CI] CCT immediately upon lens insertion and after 5 h of lens wear were 532.4 [520.3, 544.5] μm and 538.7 [526.5, 551.0] μm, respectively. Mean [95% CI] percentage change (%Δ) in CCT was 1.2% [0.9%, 1.5%], 1.2% [0.9%, 1.4%], and 0.8% [0.6%, 1.1%] for CCT, nasal PCT, and temporal PCT, respectively. There was an inverse relationship between temporal Dk/t and %ΔPCT (p < 0.05) while Dk/t was not found significantly associated with either CCT or nasal PCT. The patched eyes maintained a relatively stable CCT and showed progressive deswelling, starting and ending with 2.8% and 0.6%, respectively. In contrast, the unpatched eyes swelled, starting with nearly 0% and ending with 0.7% with a maximum swelling of 1.8%.ConclusionThere was limited amount of corneal edema induced by short-term scleral lens wear with lens Dk/t ranging from 21 to 47 hBarrer/cm and lenses with lower lens Dk/t did not induce significantly higher corneal swelling. Scleral lens insertion soon after overnight eye closure with patching did not introduce additional swelling for young and healthy eyes

Effects of Scleral-lens Tear Clearance on Corneal Edema and Post-lens Tear Dynamics: A Pilot Study.

SignificanceThe present study with small-diameter scleral lenses (SLs) revealed that post-lens tear thickness (PoLTT) was significantly associated with post-lens tear mixing, but not with central corneal edema, after short-term SL wear.PurposeThe aim of this study was to investigate the influence of SL tear clearance (PoLTT) on central corneal thickness and post-lens tear dynamics during 5-hour lens wear.MethodsNeophytes with no active ocular disease were fitted bilaterally with SLs (hofocon A; 15.6-mm diameter; ~438-μm thickness; 97 Dk; 1.44 refractive index) with various initial PoLTT values ranging from 74 to 543 μm. Central corneal thickness and PoLTT were measured using optical coherence tomography during lens wear. Tear mixing was assessed using fluorogram and "out-in" method.ResultsThe mean central corneal edema after 5-hour lens wear was 1.51% (95% confidence interval, 1.26 to 1.76%; P < .001), reached its peak at 2-hour post-lens insertion (1.65% [95% confidence interval, 1.45 to 1.85%]), and was independent of PoLTT. The fastest fluorescence decay of the post-lens tear film was observed superiorly. The fluorescence decay rate increased from center to periphery in all quadrants except superiorly. An inverse relationship was found between PoLTT and fluorescence decay rate at both 20-minute and 5-hour wear after lens insertion (P < .05). Excluding observations with out-in time exceeding 5 minutes, we found a direct relationship between PoLTT at 20 minutes after lens insertion and out-in time (P = .047). The % change in the PoLTT after 5-hour wear was greater with a thinner initial tear clearance than those with a thicker one (P = .034).ConclusionsWithin our study parameters, a thinner PoLTT under a small-diameter SL was associated with faster PoLTT mixing. However, there was no relationship between PoLTT and central corneal thickness during 5-hour SL wear

Alzheimer’s disease: amyloid-based pathogenesis and potential therapies

Alzheimer’s disease is one of the most severe neurodegenerative diseases among elderly people. Different pathogenic factors for Alzheimer’s disease have been posited and studied in recent decades, but no effective treatment has been found, necessitating further studies. In this Viewpoint article, we assess studies on the mechanisms underlying the accumulation of amyloid b (Aβ) peptide and the formation of Aβ oligomers because their accumulation in amyloid plaques in brain tissue has become a well-studied hallmark of Alzheimer’s disease. We focus on the production of Aβ and its impact on the function of synapses and neural circuits, and also discuss the clinical prospects for amyloid-targeted therapies

A generalized model via random walks for information filtering

There could exist a simple general mechanism lurking beneath collaborative filtering and interdisciplinary physics approaches which have been successfully applied to online E-commerce platforms. Motivated by this idea, we propose a generalized model employing the dynamics of the random walk in the bipartite networks. Taking into account the degree information, the proposed generalized model could deduce the collaborative filtering, interdisciplinary physics approaches and even the enormous expansion of them. Furthermore, we analyze the generalized model with single and hybrid of degree information on the process of random walk in bipartite networks, and propose a possible strategy by using the hybrid degree information for different popular objects to toward promising precision of the recommendation

Short-Term Effects of Overnight Orthokeratology on Corneal Epithelial Permeability and Biomechanical Properties

PURPOSE. To investigate the effects of 30 nights of overnight orthokeratology (OOK) on corneal epithelial permeability (P dc ) and corneal biomechanical properties. METHODS. BE Retainer and Paragon CRT lenses were used. Visits were scheduled approximately 4 hours after awakening at baseline and after 1, 5, 10, 14, and 30 days of treatment. P dc was measured at baseline and at day 30, whereas corneal biomechanical properties and visual acuities (VAs) were measured at all visits. RESULTS. Thirty-nine neophytes and soft contact lens wearers completed the study. There was no difference in P dc between baseline (ln [P dc .89] mm Hg) (P ¼ 0.001 for CH and P < 0.001 for CRF). Posttreatment VA did not reach baseline targets, and the difference was worse with low-contrast letters. Asian individuals (n ¼ 18) had significantly worse VA than non-Asian individuals (n ¼ 21) under most conditions through day 5, and the difference extended through day 14 with low-contrast letters under mesopic conditions. The percentage of participants who achieved 20/20 uncorrected was 17% Asian and 40% non-Asian individuals after day 1 and reached 69% Asian and 83% non-Asian individuals at day 30. CONCLUSIONS. Thirty nights of OOK did not alter P dc when measured 4 hours after awakening. OOK caused CH and CRF to decrease, but the changes were not clinically significant compared with diseased and postsurgical cases. Asian individuals, who had lower baseline CH in this study, responded slower to OOK based on early uncorrected VA and overrefraction measurements

Objective quantification of fluorescence intensity on the corneal surface using a modified slit-lamp technique.

ObjectivesTo improve the digital quantification of fluorescence intensity of sodium fluorescein instilled on corneal surface by modifying a slit lamp hardware and performing computerized processing of captured digital images.MethodsThe optics of a slit lamp were modified to remove corneal Purkinje reflection and to expand the illuminated area on the cornea, followed by postexperiment image processing to minimize the influence of uneven illumination. To demonstrate the feasibility and reliability of this new technique, we applied it to objective grading of corneal staining with sodium fluorescein. The results of computerized grading were compared with the results obtained using standard subjective grading of corneal staining. Objective digital grades, staining area, and staining pixel with manually and automatically defined threshold (SP-M and SP-A) were calculated for both original and processed images. Standard subjective grades of the original images were performed by 13 trained observers using National Eye Institute (NEI), Efron, and CCLRU grading scales. A series of linear regression analyses were performed to investigate the correlation between objective and subjective grades.ResultsDigital grades of the captured images were correlated significantly with subjective grades. After minimization of the artifact caused by the nonuniform illumination, correlations between digital and subjective grading were mostly strengthened. In some cases, digital grading of corneal staining was more sensitive than subjective grading methods when differentiating subtle differences of corneal staining.ConclusionsModifications performed on commercial slit-lamp hardware and the proposed digital image-processing technique have improved the quality of captured images for semiautomated quantification of fluorescein intensity on the cornea