Surface Irregularity Index Research Articles

Characterisation of symptomatic intracranial plaque without substantial stenosis using high-resolution vessel wall MRI

To characterise symptomatic intracranial plaque without substantial stenosis using three-dimensional (3D) high-resolution contrast-enhanced black-blood magnetic resonance imaging (BBMRI) and to determine plaque features associated with recent cerebrovascular events. The institutional review board approved this retrospective study. The case notes from patients with evidence of intracranial atherosclerosis in a large intracranial artery with preceding BBMRI were reviewed retrospectively. Symptomatic and asymptomatic plaques with substantial luminal stenosis (<50%) were matched by plaque location and patient age. All MRI images were de-identified and interpreted by two neuroradiologists who were blinded to the history of symptoms. Qualitative analyses including the presence of intraplaque haemorrhage (IPH), eccentricity, surface irregularity, and grade of plaque enhancement were recorded. Quantitative analyses including normal wall index and degree of contrast enhancement were calculated. Multivariate regression analysis was performed to identify the association with cerebrovascular ischaemic events. A total of 38 pairs of symptomatic and asymptomatic plaques from 74 patients were analysed. Compared to asymptomatic plaques, symptomatic plaques demonstrated higher degree of contrast enhancement (29.77±19.23 versus 18.21±12.18%, p=0.039) and presence of IPH (26% versus 8%, p=0.032). No significant differences were detected regarding eccentricity, surface irregularity, and normal wall index. Events were associated with contrast enhancement (OR, 1.212; 95% confidence interval [CI], 1.086-1.352) after controlling for age, sex, cardiovascular risk factors, and stenosis degree. IPH was not associated with events. Contrast enhancement in the intracranial plaque without substantial stenosis is associated with previous events, and may serve as the vulnerable feature, thereby stratifying stroke risk not achievable by luminal stenosis.

An Ultrasonographic Multiparametric Carotid Plaque Risk Index Associated with Cerebrovascular Symptomatology: A Study Comparing Color Doppler Imaging and Contrast-Enhanced Ultrasonography

Various ultrasonographic features of carortid plaques have been associated with the occurence of stroke, highlighting the need for multi-parametric assessment of plaque's vulnerability. Our aim was to compare ultrasonographic multiparametric indices using color Doppler imaging and contrast-enhanced sonography between symptomatic and asymptomatic carotid plaques. This was a cross-sectional observational study recruiting 54 patients (72.2% male; median age, 61 years) undergoing sonography and contrast-enhanced sonography. Patients were included if a moderately or severely stenotic internal carotid artery plaque was detected, with the plaque being considered symptomatic if it was ipsilateral to a stroke occuring within the last 6 months. A vulnerability index, previously described by Kanber et al, combined the degree of stenosis, gray-scale median, and a quantitative measure of surface irregularities (surface irregularity index) derived from color Doppler imaging and contrast-enhanced ultrasonography, resulting in 2 vulnerability indices, depending on the surface irregularity index used. Mann-Whitney U and t tests were used to compare variables between groups, and receiver operating characteristic curves were used to compare diagnostic accuracy. Sixty-two plaques were analyzed (50% symptomatic), with a mean degree of stenosis of 68.9%. Symptomatic plaques had a significantly higher degree of stenosis (mean, 74.7% versus 63.1%; P < .001), a lower gray-scale median (13 versus 38; P = .001), and a higher Kanber vulnerability index based both on color Doppler imaging (median, 61.4 versus 16.5; P < .001) and contrast-enhanced ultrasonography (median, 88.6 versus 25.2; P < .001). The area under the curve for the detection of symptomatic plaques was 0.772 for the degree of stenosis alone, 0.783 for the vulnerability index-color Doppler imaging, and 0.802 for the vulnerability index-contrast-enhanced ultrasonography, though no statistical significance was achieved. Symptomatic plaques had a higher degree of stenosis, lower gray-scale median values, and higher values of the Kanber vulnerability index using both color Doppler imaging and contrast-enhanced ultrasonography for plaque surface delineation.

Relationship between contrast sensitivity and corneal shape following overnight orthokeratology.

To evaluate the relationship between contrast sensitivity (CS) and corneal shape following overnight orthokeratology (OK). We conducted a retrospective clinical study of 80 lens-wearing myopia patients, all of whom had undergone OK and had been evaluated by Orbscan II topography. We measured the surface irregularity index (SIRI) of corneal topography at 3 and 5 mm, the size of the flattened central corneal curvature of OK lens (zone A), the size of the cornea altered by OK lens (zone B), the size of the pupillary area at the corneal level (zone C), the area of crossover between zones A and C (zone AC), the area of crossover between zones B and C (BC), the ratio of BC to B (BC/B), and the ratio of AC to C (AC/C). CS was evaluated using the CSV-1000 with spatial frequencies of 3, 6, 12, and 18 cycles/degree (CPD). Multiple correlation analyses indicated significant negative correlations between CS, zone C, BC/B, and 3-mm SIRI (all P<0.01). There were no significant differences between CS, zone B, AC/A, or 5-mm SIRI (P=0.60, 0.94 and 0.11, respectively). Zone C was negatively correlated with 3, 6, 12, and 18 CPD. 5-mm SIRI were negatively correlated with 6, 12, and 18 CPD. BC/C was negatively correlated with 6 and 18 CPD. AC/C was positively correlated with 3 CPD. Zone C, 3-mm SIRI and BC/B affect the CS following overnight OK.

Hybrid contact lenses for visual management of patients after keratoplasty

This study aims to report the outcomes of new-generation hybrid contact lenses for visual rehabilitation of postkeratoplasty patients. Twenty eyes of twenty postkeratoplasty patients were fitted with hybrid lenses. Each patient's keratometric values, ocular surface irregularity indices, central corneal thickness (CCT), uncorrected visual acuity (UCVA), spectacle-corrected visual acuity, contact lens-corrected visual acuity, contact lens fitting data, and contact lens daily wearing time were recorded. Follow-up examinations were performed at 1st week, 1st month, and 3rd month visit after successful fitting of the lenses. The mean age of the patients was 38.42 ± 4.89 years. The mean spherical component of refractive error was -4.46 ± 2.1 D, and the mean astigmatism was -5.31 ± 1.55 D. The median UCVA was 1.00 logarithm of the minimum angle of resolution (logMAR) which improved to 0.40 logMAR after spectacle correction. The median visual acuity with hybrid contact lenses was 0.05 logMAR. The median CCT was 544.4 μm and increased to 549.2 μm at 3 months after contact lens wear. The difference was not statistically significant (P = 0.38). The mean follow-up of patients was 4.32 ± 0.45 months. Eighteen of twenty patients reported a mean of 8.37 ± 1.95 h comfortable wearing time per day during this period. Two patients discontinued contact lens wearing due to conjunctival hyperemia. No graft-related complications such as decompensation, rejection, and infection were documented during the follow-up period. The new-generation hybrid contact lenses can be considered helpful in the visual management of postcorneal graft patients, particularly who are unable to achieve an adequate visual outcome with spectacles.

The Relation of Ocular Surface Irregularity and Visual Disturbance in Early Stage Acanthamoeba Keratitis.

To evaluate the relation between ocular surface irregularity and visual disturbance in early stage Acanthamoeba keratitis (AK). Fifteen patients with culture-proven AK underwent routine ophthalmic examinations, including best-corrected visual acuity (BCVA) measurement, slitlamp biomicroscope examination, and corneal fluorescein dye staining test, in both the eyes. We also evaluated the corneal sensitivity with Cochet-Bonnet esthesiometer, tear functions by Schirmer's test, and ocular surface irregularity by corneal topography and compared the results with the contralateral healthy eyes in this study. The mean logarithm of the minimum angle of resolution BCVA (0.71±0.77) was significantly lower in the eyes with AK (P=0.002). Epithelial disorders were present in all eyes, and radial keratoneuritis in 14 eyes (93.3%). The mean corneal sensitivity (39.3±24.1 mm) was significantly lower in eyes with AK compared with the healthy eyes (P=0.005). The mean Schirmer's test value (22.5±12.0 mm) in eyes with AK was significantly higher compared with the healthy eyes (P=0.01). The ocular surface irregularity indices (the surface regularity index, 2.47±0.42; the surface asymmetry index, 3.24±1.31) were significantly higher in eyes with AK compared with contralateral healthy eyes (P<0.0001 and P<0.0001, respectively). The ocular surface disease in AK is associated with decrease in corneal sensitivity and increase in Schirmer's test value and ocular surface irregularity indices. The visual disturbance in AK may owe not only to corneal haze but also to ocular surface irregularity.

Color light-emitting diode reflection topography: validation of keratometric repeatability in a large sample of wide cylindrical-range corneas.

PurposeTo investigate repeatability of steep and flat keratometry measurements, as well as astigmatism axis in cohorts with normal range and regular astigmatic such as: eyes following laser-assisted in situ keratomileusis (LASIK) and normal population, as well as cohorts of high and irregular astigmatism such as keratoconic eyes, and keratoconic eyes following corneal collagen cross-linking, employing a novel corneal reflection topography device.MethodsSteep and flat keratometry and astigmatism axis measurement repeatability was investigated employing a novel multicolored-spot reflection topographer (Cassini) in four study groups, namely a post myopic LASIK-treated Group A, a keratoconus Group B, a post-CXL keratoconus Group C, and a control Group D of routine healthy patients. Three separate, maps were obtained employing the Cassini, enabling investigation of the intra-individual repeatability by standard deviation. Additionally we investigated in all groups,the Klyce surface irregularity indices for keratoconus, the SAI (surface asymmetry index) and the SRI (surface regularity index).ResultsFlat keratometry repeatability was 0.74±0.89 (0.03 to 5.26) diopters (D) in the LASIK Group A, 0.88±1.45 (range minimum to maximum, 0.00 to 7.84) D in the keratoconic Group B, and 0.71±0.94 (0.02 to 6.23) D in the cross-linked Group C. The control Group D had flat keratometry repeatability 0.36±0.46 (0.00 to 2.71) D. Steep keratometry repeatability was 0.64±0.82 (0.01 to 4.81) D in the LASIK Group A, 0.89±1.22 (0.02 to 7.85) D in the keratoconic Group B, and 0.93±1.12 (0.04 to 5.93) D in the cross-linked Group C. The control Group D had steep keratometry repeatability 0.41±0.50 (0.00 to 3.51) D. Axis repeatability was 3.45±1.62° (0.38 to 7.78°) for the LASIK Group A, 4.12±3.17° (0.02 to 12.13°) for the keratoconic Group B, and 3.20±1.99° (0.17 to 8.61°) for the cross-linked Group C. The control Group D had axis repeatability 2.16±1.39° (0.05 to 5.86°). The SAI index measurement repeatability was 0.33±0.40 (0.01 to 2.31) in the post-LASIK Group A, 0.39±0.75 (0.00 to 7.15) in the keratoconic Group B, and 0.43±0.56 (0.05 to 3.50) in the keratoconus post-CXL Group C. The control group had SAI measurement repeatability of 0.26±0.30 (0.00 to 2.39). The SRI index repeatability was 0.22±0.17 (0.01 to 0.96) for post-LASIK Group A, 0.20±0.18 (0.00 to 1.07) in keratoconic Group B, and 0.13±0.09 (0.00 to 0.45) in the keratoconus post-CXL Group C. The control Group D had SRI measurement repeatability of 0.23±0.16 (0.00 to 0.75).ConclusionThis novel corneal topography device appears to offer very high specificity in estimating corneal keratometry and specific corneal irregularity indices, even in topographically challenging corneas such as LASIK treated, keratoconic, and cross-linked.

A Novel Ultrasound-Based Carotid Plaque Risk Index Associated with the Presence of Cerebrovascular Symptoms.

The purpose of this study was to determine the efficacy of a novel ultrasound-based carotid plaque risk index (CPRI) in predicting the presence of cerebrovascular symptoms in patients with carotid artery stenosis. This was a cross-sectional, observational study involving 56 patients (mean age 76.6 years, 62.5 % male). Plaque grayscale median (GSM) and surface irregularity indices (SII) were measured in 82 stenosed carotid arteries (range 10 - 95 %) and combined with the degree of stenosis (DOS) in the form of (DOS*SII)/(1 + GSM). A reduced index DOS/(1 + GSM) not incorporating plaque surface irregularities was also investigated. Receiver operating characteristic curves (ROC) were used to study the diagnostic efficacy of CPRI, comparing against DOS and an equivalent risk index constructed using a conventional logistic regression based method with model parameters optimized to the dataset (CPRIlogistic). There were 42 stenosed carotid arteries with cerebrovascular symptoms, and 40 without symptoms. The presence of symptoms significantly correlated with DOS, GSM and SII (p < 0.01). The median CPRI of the symptomatic (asymptomatic) groups were 23.2 (9.2) compared with 0.71 (0.30) for CPRIlogistic (p < 0.01). The diagnostic performance of CPRI exceeded that of CPRIlogistic and DOS, and demonstrated a better separation of the symptomatic and asymptomatic groups. Our novel risk index combines quantitative measures of carotid plaque echogenicity and surface irregularities with the degree of stenosis. It is a better predictor of cerebrovascular symptoms than the degree of stenosis and could be valuable in studies and clinical trials aimed at identifying vulnerable carotid artery stenoses.

Keratoconus management: long-term stability of topography-guided normalization combined with high-fluence CXL stabilization (the Athens Protocol).

To investigate refractive, topometric, pachymetric, and visual rehabilitation changes induced by anterior surface normalization for keratoconus by partial topography-guided excimer laser ablation in conjunction with accelerated, high-fluence cross-linking. Two hundred thirty-one keratoconic cases subjected to the Athens Protocol procedure were studied for visual acuity, keratometry, pachymetry, and anterior surface irregularity indices up to 3 years postoperatively by Scheimpflug imaging (Oculus Optikgeräte GmbH, Wetzlar, Germany). Mean visual acuity changes at 3 years postoperatively were +0.38 ± 0.31 (range: -0.34 to +1.10) for uncorrected distance visual acuity and +0.20 ± 0.21 (range: -0.32 to +0.90) for corrected distance visual acuity. Mean K1 (flat meridian) keratometric values were 46.56 ± 3.83 diopters (D) (range: 39.75 to 58.30 D) preoperatively, 44.44 ± 3.97 D (range: 36.10 to 55.50 D) 1 month postoperatively, and 43.22 ± 3.80 D (range: 36.00 to 53.70 D) up to 3 years postoperatively. The average Index of Surface Variance was 98.48 ± 43.47 (range: 17 to 208) pre-operatively and 76.80 ± 38.41 (range: 7 to 190) up to 3 years postoperatively. The average Index of Height Decentration was 0.091 ± 0.053 μm (range: 0.006 to 0.275 μm) preoperatively and 0.057 ± 0.040 μm (range: 0.001 to 0.208 μm) up to 3 years postoperatively. Mean thinnest corneal thickness was 451.91 ± 40.02 μm (range: 297 to 547 μm) preoperatively, 353.95 ± 53.90 μm (range: 196 to 480 μm) 1 month postoperatively, and 370.52 ± 58.21 μm (range: 218 to 500 μm) up to 3 years postoperatively. The Athens Protocol to arrest keratectasia progression and improve corneal regularity demonstrates safe and effective results as a keratoconus management option. Progressive potential for long-term flattening validates using caution in the surface normalization to avoid overcorrection.

Quantitative assessment of carotid plaque surface irregularities and correlation to cerebrovascular symptoms

BackgroundThe purpose of this study was to determine whether surface irregularities measured from ultrasound images of carotid artery plaques and quantified using a novel method, correlate with the presence of ipsilateral hemispheric cerebrovascular symptoms.MethodsA plaque surface irregularity index (SII) was measured in 47 carotid artery plaques (32 subjects, stenosis range 10% -95%, 49% symptomatic) using ultrasound image sequences spanning several cardiac cycles. The differences in the distribution of SII in plaques with ipsilateral hemispheric symptoms versus those without symptoms and the correlation between the SII of plaques and the degrees of stenosis of the corresponding arteries were assessed. Diagnostic performance of plaque SII was evaluated on its own and in combination with the degree of stenosis.ResultsThe mean SII was significantly greater for plaques with ipsilateral hemispheric symptoms (1.89 radians/mm) than for asymptomatic plaques (1.67 radians/mm, p = 0.03). There was no statistically significant association between the SII and the degree of stenosis (p = 0.30). SII predicted the presence of cerebrovascular symptoms with an accuracy of 66% (sensitivity 65%, specificity 67%) on its own and with an accuracy of 83% (sensitivity 96%, specificity 71%) in combination with the degree of stenosis.ConclusionsQuantitative assessment of carotid plaque surface irregularities using a novel SII parameter correlates with the presence ipsilateral hemispheric cerebrovascular symptoms and may increase diagnostic performance beyond that provided by the degree of stenosis.

Wall motion in the stenotic carotid artery: association with greyscale plaque characteristics, the degree of stenosis and cerebrovascular symptoms

BackgroundSystolic dilation of the atherosclerotic carotid artery depends on several factors including arterial compliance and the haemodynamic environment. The purpose of this study was to quantify wall motion in stenotic carotid arteries and investigate any associations with the ultrasound greyscale plaque characteristics, the degree of stenosis, and the presence of cerebrovascular symptoms.MethodsVariations in the lumen diameters of 61 stenotic carotid arteries (stenosis range 10%-95%) from 47 patients were measured before the proximal shoulder of the atherosclerotic plaque using ultrasound image sequences over several cardiac cycles. Absolute and percentage diameter changes from diastole to systole were calculated and their relationship to the degree of stenosis, greyscale plaque characteristics, and the presence of ipsilateral hemispheric symptoms were studied.ResultsThe mean absolute diameter change from diastole to systole was 0.45 mm (s.d. 0.17), and the mean percentage diameter change was 6.9% (s.d. 3.1%). Absolute and percentage diameter changes did not have a statistically significant relationship to the degree of stenosis, greyscale plaque characteristics, or the presence of ipsilateral hemispheric symptoms (p > 0.05). Parameters significantly correlated with the presence of symptoms were the degree of stenosis (p = 0.01), plaque greyscale median (p = 0.02) and the plaque surface irregularity index (p = 0.02).ConclusionsOur study confirmed the degree of stenosis, plaque greyscale median and our surface irregularity index were significant predictors of symptoms, but found no significant correlation between diameter changes of stenosed carotid arteries and the presence of ipsilateral hemispheric symptoms.

Revisiting keratoconus diagnosis and progression classification based on evaluation of corneal asymmetry indices, derived from Scheimpflug imaging in keratoconic and suspect cases

PurposeTo survey the standard keratoconus grading scale (Pentacam®-derived Amsler–Krumeich stages) compared to corneal irregularity indices and best spectacle-corrected distance visual acuity (CDVA).Patients and methodsTwo-hundred and twelve keratoconus cases were evaluated for keratoconus grading, anterior surface irregularity indices (measured by Pentacam imaging), and subjective refraction (measured by CDVA). The correlations between CDVA, keratometry, and the Scheimpflug keratoconus grading and the seven anterior surface Pentacam-derived topometric indices – index of surface variance, index of vertical asymmetry, keratoconus index, central keratoconus index, index of height asymmetry, index of height decentration, and index of minimum radius of curvature – were analyzed using paired two-tailed t-tests, coefficient of determination (r2), and trendline linearity.ResultsThe average ± standard deviation CDVA (expressed decimally) was 0.626 ± 0.244 for all eyes (range 0.10–1.00). The average flat meridian keratometry was (K1) 46.7 ± 5.89 D; the average steep keratometry (K2) was 51.05 ± 6.59 D. The index of surface variance and the index of height decentration had the strongest correlation with topographic keratoconus grading (P < 0.001). CDVA and keratometry correlated poorly with keratoconus severity.ConclusionIt is reported here for the first time that the index of surface variance and the index of height decentration may be the most sensitive and specific criteria in the diagnosis, progression, and surgical follow-up of keratoconus. The classification proposed herein may present a novel benchmark in clinical work and future studies.

Evaluation of Visual Acuity, Pachymetry and Anterior-Surface Irregularity in Keratoconus and Crosslinking Intervention Follow-up in 737 Cases

ABSTRACT Purpose To investigate visual acuity, corneal pachymetry, and anterior-surface irregularity indices correlation with keratoconus severity in a very large pool of clinically-diagnosed untreated keratoconic eyes, and in keratoconic eyes subjected to crosslinking intervention. Materials and methods Total of 737 keratoconic (KCN) cases were evaluated. Group A was formed from 362 untreated keratoconic eyes, and group B from 375 keratoconic eyes subjected to partial normalization via topography-guided excimer laser ablation and high-fluence collagen crosslinking. A control group C of 145 healthy eyes was employed for comparison. We investigated distance visual acuity, uncorrected (UDVA), best-spectacle corrected (CDVA), and Scheimpflug-derived keratometry, pachymetry (central corneal thickness, CCT and thinnest, TCT), and two anterior-surface irregularity indices, the index of surface variance (ISV) and the index of height decentration (IHD). The correlations between these parameters vs topographic keratoconus classification (TKC) were investigated. Results Keratometry for group A was K1 (flat) 46.67 ± 3.80 D and K2 (steep) 50.76 ± 5.02 D; for group B K1 44.03 ± 3.64 D and K2 46.87 ± 4.61 D; for group C, K1 42.89 ± 1.45 D and K2 44.18 ± 1.88 D. Visual acuity for group A was UDVA 0.12 ± 0.18 and CDVA 0.59 ± 0.25 (decimal), for group B, 0.51 ± 0.28 and 0.77 ± 0.22, and for group C, 0.81 ± 0.31 and 0.87 ± 0.12. Correlation between ISV and TKC (r2) was for group A 0.853, and for group-B 0.886. Correlation between IHD and TKC was for group A r2 = 0.731, and for group B 0.701. The ROC analysis ‘area under the curve’ was for CDVA 0.550, TCT 0.596, ISV 0.876 and IHD 0.887. Conclusion Our study indicates that the traditionally employed metrics of visual acuity and corneal thickness may not be robust indicators nor provide accurate assessment on either keratoconus severity or postoperative evaluation. Two anterior surface irregularity indices, derived by Scheimpflug-imaging, ISV and IHD, may be more sensitive and specific tools. Précis Visual acuity, Scheimpflug-derived pachymetry and anterior-surface irregularity correlation to keratoconus severity in untreated cases (A), treated with crosslinking (B), and in a control group (C) reveals that visual acuity and pachymetry do not correlate well with keratoconus severity. How to cite this article Kanellopoulos AJ, Moustou V, Asimellis G. Evaluation of Visual Acuity, Pachymetry and Anterior-Surface Irregularity in Keratoconus and Crosslinking Intervention Follow-up in 737 Cases. J Kerat Ect Cor Dis 2013;2(3):95-103.

Outcome of penetrating keratoplasty performed by cornea fellows compared with that of an experienced staff surgeon

This retrospective study compared the best corrected visual acuity, refractive and topographic astigmatism, other corneal indices, and graft clarity of 94 penetrating keratoplasties performed by nine supervised corneal fellows with those of 108 penetrating keratoplasties performed by an experienced staff surgeon. Refractive and topographic evaluations were performed after removal of all interrupted 10-0 nylon sutures while a continuous 11-0 nylon suture remained in place. Graft clarity was assessed at the final follow-up. Mean BXVA was 0.49 logMAR (20/61) ± 4.3 lines (fellows) and 0.47logMAR (20/59) ± 3.9 lines (staff). Mean postoperative refractive astigmatism was 3.77 ± 1.97 diopters (fellows) and 3.49 ± 1.94 diopters (staff). Mean postoperative astigmatic astigmatism was 4.60 ± 2.7 diopters (fellows) and 4.08 ± 2.41 diopters (staff). Mean surface asymmetry index (SAI) was 1.89 ± 1.42 (fellows) and 1.61 ± 1.08 (staff). Mean surface irregularity index (SRI) was 1.43 ± 0.72 (fellows) and 1.45 ± 0.61 (staff). In the fellow group, 85 cases (90%) were clear over a mean follow-up of 32 months and in the staff group 100 grafts (93%) remained clear over a mean follow-up of 38 months. Simple and multiple regression analysis indicated no significant differences between the two groups in all outcome measures. The authors conclude that properly supervised corneal fellows in training achieved favorable penetrating keratoplasty results that were comparable to those of an experienced staff surgeon.—Michael D. Wagoner

Predicting time to refractive stability after discontinuation of rigid contact lens wear before refractive surgery

This was a retrospective study to determine the length of time required to reach refractive stability after discontinuation of rigid contact lens wear for purposes of preoperative evaluation for refractive surgery. Patients were examined at 3-week intervals after discontinuation of rigid contact lens wear, at which time visual acuity, subjective refraction, and corneal topography were performed. Stability was defined 2 consecutive examinations in which the refraction was within ± 0.25 diopter (D) sphere and 0.25 D cylinder with less than 25 degrees of axis orientation. Thirty-one (56.4%) of 55 eyes achieved stability by the second visit, suggesting that stability had been achieved within 3 weeks of discontinuation of lens wear. Twenty-four (43.6%) eyes required more than 2 visits to achieve stability, confirming instability still existed 3 weeks after discontinuation of lens wear. The number of years of contact lens was statistically significantly correlated with the likelihood of requiring longer time to reach refractive stability (P = .05). No statistically-significant between-group difference was observed in age, gender, refractive cylinder, topographic cylinder, difference between refractive and topographic cylinders, surface irregularity index, surface asymmetry index, or spherical equivalent at initial examination. The conclusion was that the length of time required to reach refractive stability after cessation of rigid contact lens wear is highly variable, especially for long-term wearers, and that the customary 3-week interval used by many refractive surgeons does not always allow sufficient time to obtain accurate preoperative measurements. —Michael D. Wagoner This was a retrospective study to determine the length of time required to reach refractive stability after discontinuation of rigid contact lens wear for purposes of preoperative evaluation for refractive surgery. Patients were examined at 3-week intervals after discontinuation of rigid contact lens wear, at which time visual acuity, subjective refraction, and corneal topography were performed. Stability was defined 2 consecutive examinations in which the refraction was within ± 0.25 diopter (D) sphere and 0.25 D cylinder with less than 25 degrees of axis orientation. Thirty-one (56.4%) of 55 eyes achieved stability by the second visit, suggesting that stability had been achieved within 3 weeks of discontinuation of lens wear. Twenty-four (43.6%) eyes required more than 2 visits to achieve stability, confirming instability still existed 3 weeks after discontinuation of lens wear. The number of years of contact lens was statistically significantly correlated with the likelihood of requiring longer time to reach refractive stability (P = .05). No statistically-significant between-group difference was observed in age, gender, refractive cylinder, topographic cylinder, difference between refractive and topographic cylinders, surface irregularity index, surface asymmetry index, or spherical equivalent at initial examination. The conclusion was that the length of time required to reach refractive stability after cessation of rigid contact lens wear is highly variable, especially for long-term wearers, and that the customary 3-week interval used by many refractive surgeons does not always allow sufficient time to obtain accurate preoperative measurements. —Michael D. Wagoner

Characteristics of skin surface morphology and transepidermal water loss in clinically normal-appearing skin of patients with atopic dermatitis: a video-microscopy study.

In patients with atopic dermatitis (AD), it is debatable whether clinically normal-appearing skin is equal to non-atopic normal skin. The aim of this study was to quantitatively evaluate the characteristics of normal-appearing skin of AD. We examined the value of skin surface morphological changes using a new, simple, computer-assisted method with a video microscope. We also investigated the physiological function as represented by transepidermal water loss (TEWL) levels in 44 patients with AD and 15 normal controls. The morphological changes were represented by a variation coefficient score that reflected the irregularity of skin ridges, named the surface irregularity index (SII). There were significant differences between the normal-appearing skin of AD and non-atopic normal skin in both SII (P<0.001) and in TEWL (P<0.01). Especially for the SII, there were significant differences between AD subgroups subdivided by peripheral blood eosinophil count (Eo), serum lactate dehydrogenase level, and clinical score. TEWL values were significantly higher in the high-Eo AD group (n=15) than in the low-Eo AD group (n=29) (P<0.05). These findings indicate that clinically normal-appearing skin of AD patients with high disease activity differs from non-atopic normal skin in both surface morphology and physiology and that these changes reflect the current disease activity.

Surface Morphology Study of Solid Powders Evaluated by Particle Size Distribution and Nitrogen Adsorption

The surface morphology of five tableting excipients including unmilled dicalcium phosphate dihydrate (Di-Tab), microcrystalline cellulose (Avicel PH102), corn starch, croscarmellose sodium (Ac-di-sol), and sodium starch glycolate (Primojel) was studied using laser scattering particle size analysis and nitrogen adsorption surface area analysis. The surface area of particles disregarding porosity was obtained from the particle size distribution and the total area was obtained from the B.E.T. treatment of nitrogen adsorption results. The so-called Surface Irregularity Index (SII) was established to indicate surface roughness due to porosity. The SII value was consistent with the microscopic visualization of a powder sample. Furthermore, the nitrogen adsorption-desorption isotherm hysteresis which showed the evidence of porosity was also consistent with the index. The SII may be an alternative way to characterize the surface morphology of a solid powder.