Comparison of accuracy of different intraocular lens power calculation methods using artificial intelligence

PURPOSE

To assess the accuracy of the intraocular lens (IOL) power calculation based on three methods using artificial intelligence (AI) and one formula using no AI.

METHODS

During cataract surgery on 114 eyes, one type of IOL was implanted, calculated with the Hill-RBF 2.0 method. The theoretical postoperative refractions were calculated using the Kane and the Pearl-DGS methods and a vergence based formula (Barrett Universal II, BUII). The differences between the manifest and objective postoperative refractions and the predicted refractions were calculated. The percentage of eyes within ±0.5 D and ±1.0 D prediction error (PE), the mean, and the median absolute errors (MAE and MedAE) were also determined.

RESULTS

The mean age of the patients was 69.48 years; the axial length was between 21.19 and 25.39 mm. The number of eyes within ±0.5/±1.0 D PE was 96/108 (84.21%/94.73%) using the Hill-RBF 2.0 method, 92/107 (80.70%/93.85%) with the Kane method, 91/107 (79.82%/93.85%) with the Pearl-DGS method, and 91/106 (79.82%/92.98%) with the BUII formula, using subjective refraction. With objective refractometric data, PEs were within ±0.5 D in 88 (77.19%), 83 (72.80%), 82 (71.92%), and 80 (70.17%) cases (Hill-RBF, Kane, Pearl-DGS, BUII, respectively). MAE and MedAE were also best with the Hill-RBF 2.0 method (0.3 D; 0.18 D).

CONCLUSION

Better accuracy of PE might be obtained by the Hill-RBF 2.0 method compared with BUII. The Kane and Pearl-DGS methods showed similar accuracy when compared with BUII.

Accuracy of the Hill-radial basis function method and the Barrett Universal II formula

PURPOSE

The aim was to assess the postoperative results of a biometric method using artificial intelligence (Hill-radial basis function 2.0), and data from a modern formula (Barrett Universal II) and the Sanders-Retzlaff-Kraft/Theoretical formula.

METHODS

Phacoemulsification and biconvex intraocular lens implantation were performed in 186 cataractous eyes. The diopters of intraocular lens were established with the Hill-radial basis function method, based on biometric data obtained using the Aladdin device. The required diopters of the intraocular lens were also calculated by the Barrett Universal II formula and with the Sanders-Retzlaff-Kraft/Theoretical formula. The differences between the manifest postoperative refractive errors and the planned refractive errors were calculated, as well as the percentage of eyes within ±0.5 D of the prediction error. The mean- and the median absolute refractive errors were also determined.

RESULTS

The mean age of the patients was 70.13 years (SD = 10.67 years), and the mean axial length was 23.47 mm (range = 20.72-28.78 mm). The percentage of eyes within a prediction error of ±0.5 D was 83.62% using the Hill-radial basis function method, 79.66% with the Barrett Universal II formula, and 74.01% in the case of the Sanders-Retzlaff-Kraft/Theoretical formula. The mean- and the median absolute refractive errors were not statistically different.

CONCLUSION

Clinical success was the highest when using the biometric method, based on pattern recognition. The results obtained using Barrett Universal II came a close second. Both methods performed better compared to a traditionally used formula.

Ocular measurements of a swept-source biometer: Repeatability data and comparison with an optical low-coherence interferometry biometer

PURPOSE

To assess the repeatability of a swept-source biometer in phakic and pseudophakic patients, including astigmatism analysis, and to compare measurement data with those obtained by an optical low-coherence interferometry method.

SETTING

Borsod-Abaúj-Zemplén County Central Hospital and University Teaching Hospital, Miskolc, Hungary.

DESIGN

Evaluation of diagnostic technologies.

METHODS

One eye of each patient was examined with the Argos and Aladdin devices. With the Argos, three repeated measurements were performed. Biometric parameters and cross-cylinder power vector components of astigmatism were assessed. Descriptive and repeatability data of the Argos were observed, and Bland-Altman plots were created.

RESULTS

The study comprised 96 eyes (50 phakic and 46 pseudophakic) of 96 patients (mean age 69.22 years and 71.14 years, respectively). The two devices showed a significant difference regarding astigmatism and corneal diameter in the phakic group (measured larger by Argos, P < .05). In the pseudophakic group, only the corneal diameter data were significantly different (measured larger by Argos, P = .02). No other statistically significant differences were observed in either group. An excellent intraclass correlation coefficient (ICC) was reported on the Argos device in the case of all measured parameters except for the diopter values of astigmatism and the vector values of the astigmatism in the phakic group. In the pseudophakic group, the ICC was moderate in the case of anterior chamber depth (ACD) and good in the case of astigmatism and vectorial data.

CONCLUSIONS

The repeatability data regarding the Argos biometer were excellent for all parameters except astigmatism data in both groups and ACD readings in the pseudophakic group. However, only a limited agreement was observed between these devices in both groups.

Long-Term Changes in Backscattered Light Measurements in Keratoconus Corneas Treated with Collagen Cross-Linking

PURPOSE

Our aim was to compare densitometry data between keratoconus and normal corneas and to assess the long-term changes in corneal backscattered light values after corneal collagen cross-linking (CXL) treatment.

MATERIAL AND METHODS

Retrospective analysis was performed on 26 eyes of normal patients (age: 32.71 ± 12.68 years) and 39 eyes of keratoconus patients (28.93 ± 7.59 years) using the Pentacam HR corneal densitometry module before CXL and during the postoperative period, which lasted a mean of 2.53 years (range: 1-4 years). Corneal backscattered light values in grey scale unit (GSU) were recorded for the anterior 120 µm, the center layer, and the posterior 60 µm of the cornea in four concentric, central rings. An additional calculation was performed with converting GSU values to GSU/cubic millimeters (mm³) with surface area calculations and using corneal thickness data.

RESULTS

Statistically significant differences were observed between normal and keratoconus group densitometry values (in GSU/mm³) in all annuli of the center layer; all, but anterior layer of the 10-12 annuli; all annuli of the total thickness and in all values of the total diameter. In all these cases, the normal cornea showed higher GSU/mm³ values compared to keratoconus corneas (p < 0.05). One month after the CXL treatment, the GSU/mm³ data increased significantly in the anterior, the center, and the posterior zone (p < 0.05), followed by its slow decrease. At the end of the follow-up period, the GSU/mm³ values were significantly higher in all three zones compared to those before the CXL treatment (p < 0.01).

CONCLUSION

Densitometry measurements can reflect the changes of optical quality of the cornea. These measurements may play a valuable role in assessing keratoconus and optical changes of the corneas after CXL treatment.

Corneal biomechanical data and biometric parameters measured with Scheimpflug-based devices on normal corneas

AIM

To analyze the correlations between ocular biomechanical and biometric data of the eye, measured by Scheimpflug-based devices on healthy subjects.

METHODS

Three consecutive measurements were carried out using the corneal visualization Scheimpflug technology (CorVis ST) device on healthy eyes and the 10 device-specific parameters were recorded. Pentacam HR-derived parameters (corneal curvature radii on the anterior and posterior surfaces; apical pachymetry; corneal volume; corneal aberration data; depth, volume and angle of the anterior chamber) and axial length (AL) from IOLMaster were correlated with the 10 specific CorVis ST parameters.

RESULTS

Measurements were conducted in 43 eyes of 43 volunteers (age 61.24±15.72y). The 10 specific CorVis ST data showed significant relationships with corneal curvature radii both on the anterior and posterior surface, pachymetric data, root mean square (RMS) data of lower-order aberrations, and posterior RMS of higher-order aberrations and spherical aberration of the posterior cornea. Anterior chamber depth showed a significant relationship, but there were no significant correlations between corneal volume, anterior chamber volume, mean chamber angle or AL and the 10 specific CorVis ST parameters.

CONCLUSIONS

CorVis ST-generated parameters are influenced by corneal curvature radii, some corneal RMS data, but corneal volume, anterior chamber volume, chamber angle and AL have no correlation with the biomechanical parameters. The parameters measured by CorVis ST seem to refer mostly to corneal properties of the eye.

Ocular biomechanical measurements on post-keratoplasty corneas using a Scheimpflug-based noncontact device

AIM

To analyse ocular biomechanical properties, central corneal thickness (CCT) and intraocular pressure (IOP) in post-keratoplasty eyes, as compared to normal subjects, with a new Scheimpflug-based technology. Moreover, biomechanical data were correlated with the size and age of the donor and recipient corneas.

METHODS

Measurements were conducted on 46 eyes of 46 healthy patients without any corneal pathology (age: 53.83±20.8y) and 30 eyes of 28 patients after penetrating keratoplasty (age: 49.43±21.34y). Ten biomechanical parameters, the CCT and IOP were recorded by corneal visualization scheimpflug technology (CorVis ST) using high-speed Scheimpflug imaging. Keratometry values were also recorded using Pentacam HR system. Scheimpflug measurements were performed after 43.41±40.17mo (range: 11-128mo) after the keratoplasty and after 7.64±2.34mo (range: 5-14mo) of suture removal.

RESULTS

Regarding the device-specific biomechanical parameters, the highest concavity time and radius values showed a significant decrease between these two groups (P=0.01 and P<0.001). None of other biomechanical parameters disclosed a significant difference. The CCT showed a significant difference between post-keratoplasty eyes as compared to normal subjects (P=0.003) using the CorVis ST device. The IOP was within the normal range in both groups (P=0.84). There were no significant relationships between the keratometric data, the size of the donor and recipient, age of the donor and recipient and biomechanical properties obtained by CorVis ST.

CONCLUSION

The ocular biomechanics remain stable after penetrating keratoplasty according to the CorVis ST measurements. Only two from the ten device-specific parameters have importance in the follow-up period after penetrating keratoplasty.

Repeatability data and agreement of keratometry with the VERION system compared to the IOLMaster

PURPOSE

To analyze the repeatability of keratometric and white-to-white (WTW) distance measurements with the VERION Measurement Module (Alcon Laboratories, Inc., Fort Worth, TX) and to compare the measured data to the results of the IOLMaster (Carl Zeiss Meditec, Jena, Germany).

METHODS

Three images were captured with the VERION and the flattest and steepest keratometric data, the astigmatism axis, and the WTW distance were recorded. Subsequently, the axial length, the keratometric data with axis, and the WTW distance were measured with an IOLMaster. The repeatability data of the keratometric value of the VERION System, converted to cross cylinder J0 and J45 vector components, were analyzed. The agreement data for keratometry obtained by the VERION System and the differences regarding keratometric data and WTW distance compared to IOLMaster were calculated.

RESULTS

The measurements were conducted in 50 eyes of 50 healthy volunteers (median age: 50.32 years, range: 19.34 to 85.3 years). The flattest and the steepest keratometric data, the diopter of astigmatism, the J0 and J45 vector components, and WTW distance did not differ significantly between devices (P > .05). Intraclass correlation coefficients (range: 0.863 to 0.994) and Cronbach's alpha values (range: 0.950 to 0.998) were high for all parameters measured by the VERION System.

CONCLUSIONS

The VERION System has high repeatability and agreement with the IOLMaster, making it suitable as an alternative tool in clinical practice.

Analysis of surgically induced astigmatism on the posterior surface of the cornea

PURPOSE

To measure surgically induced astigmatism (SIA) on the posterior surface of the cornea using Scheimpflug-based keratometry on eyes with with-the-rule astigmatism.

METHODS

Repeated Scheimpflug-based keratometry was obtained preoperatively and a mean of 8.65 weeks postoperatively following superior clear corneal incisions. Differences in the keratometric values and SIA were determined on the anterior and posterior surfaces separately and the data were analyzed.

RESULTS

The study included 88 eyes of 88 patients (age range: 46.4 to 87.5 years), with the steepest total corneal meridian between 75° and 105°. Preoperatively, the magnitude of the anterior and posterior corneal astigmatism was 0.74 ± 0.44 and 0.29 ± 0.14 diopters (D), respectively, which was greater than 0.5 D in 10 eyes (11.36%). The difference between preoperative and postoperative keratometric data on the posterior surface was significant, as was the difference between the preoperative and postoperative posterior astigmatism. The mean magnitude of posterior corneal SIA was 0.32 ± 0.29 D, which was 0.5 D or greater in 22 eyes (25.00%). A statistically significant correlation was observed between the diopter of the preoperatively measured posterior corneal astigmatism and the postoperative SIA on the posterior surface (r = 0.34, P = .001). The correlation was not significant between SIA on the anterior and posterior surfaces (r = 0.10, P = .36).

CONCLUSIONS

SIA on the posterior surface of the cornea may have a significant role, especially in cases of toric intraocular lens implantation. Posterior corneal astigmatism and SIA may have a significant clinical impact on more precise planning of cataract surgeries.

Scheimpflug imaged corneal changes on anterior and posterior surfaces after collagen cross-linking

AIM

To compare the anterior and posterior corneal parameters before and after collagen cross-linking therapy for keratoconus.

METHODS

Collagen cross-linking was performed in 31 eyes of 31 keratoconus patients (mean age 30.6±8.9y). Prior to treatment and an average 7mo after therapy, Scheimpflug analysis was performed using Pentacam HR. In addition to corneal thickness assessments, corneal radius, elevation, and aberrometric measurements were performed both on anterior and posterior corneal surfaces. Data obtained before and after surgery were statistically analyzed.

RESULTS

In terms of horizontal and vertical corneal radius, and central corneal thickness no deviations were observed an average 7mo after operation. Corneal higher order aberration showed no difference neither on anterior nor on posterior corneal surfaces. During follow-up period, no significant deviation was detected regarding elevation values obtained by measurement in mm units between the 3.0-8.0 mm-zones.

CONCLUSION

Corneal stabilization could be observed in terms of anterior and posterior corneal surfaces, elevation and higher order aberration values 7mo after collagen cross-linking therapy for keratoconus.

Assessment of endothelial cell density and corneal thickness in corneal grafts an average of 5 years after penetrating keratoplasty

BACKGROUND

Corneal transparency is a useful indicator for corneal function. Our aim was to investigate central corneal endothelial cells and corneal thickness in transplanted corneas at an average of 5.4 years after penetrating keratoplasty

PATIENTS AND METHODS

The study involved 68 perforated keratoplasty patients with at least a 1 year follow-up. Post-operatively, the central corneal endothelial layer was observed using a contact specular microscope. Central endothelial cell density, corneal thickness and the coefficient of variation of endothelial size were statistically analysed.

RESULTS

The post-operative follow-up time was ranging from 12 months to 23 years. Endothelial cell density (ECD) was 1,501 ± 249 cell/mm(2). The average cell size was 673.6 ± 98.3 μm(2), and the coefficient of variation of cell size was 0.61 ± 0.11. No difference in ECD was detected between diagnostic groups. Corneal thickness was 0.56 ± 0.06 mm. Correlation between ECD and post-operative time was not significant (r = 0.02; p = 0.85).

CONCLUSION

Our study concluded that ECD showed a higher rate of decrease after penetrating keratoplasty with no relation to pre-operative diagnosis.

Collagen cross-linking in the treatment of pellucid marginal degeneration

Pellucid marginal degeneration (PMD) is an uncommon cause of inferior peripheral corneal thinning disorder, characterized by irregular astigmatism. We analyzed a case of bilateral PMD patient and treated one eye with corneal collagen cross-linking (CXL) therapy. Corneal topography was characteristic for PMD. Visual acuity, slitlamp examinations, tonometry, and corneal thickness were observed. Simulated keratometric and topographic index values were detected with corneal topography. Uncorrected, LogMAR visual acuity has improved from +0.8 to +0.55 during the 6 months and +0.3 during the 8 months follow-up after CXL. Pachymetry values and intraocular pressure showed no changes. Keratometric values and topografic indexes disclosed no progression of the disease. CXL may postpone or eliminate the need of corneal transplantation in cases with PMD.

Analysis of age-dependence of the anterior and posterior cornea with scheimpflug imaging

PURPOSE

To assess keratometric and higher-order aberrations of the anterior and posterior cornea and their age-related changes.

METHODS

This study investigated one healthy eye of 227 patients (mean age: 55.15 ± 21.2 years; range: 16 to 90 years; 135 right eyes, 92 left eyes). Images were captured from each eye with Pentacam HR (Oculus Optikgeräte GmbH, Wetzlar, Germany) using automatic mode. Keratometric, astigmatism data, and corneal higher-order aberrations were analyzed.

RESULTS

With respect to laterality, no deviance was found in any of the parameters (P > .05). Mean refractive error was 0.52 ± 0.23 diopters. The level of astigmatism decreased significantly with advancing age for both the anterior and posterior corneal surfaces (P < .05). The overall root mean square of the higher-order aberration increased continuously with age (r = 0.517; P < .01), which can be explained by the combined effect of the increased in both the anterior and posterior corneal root mean square higher-order aberrations. Of the higher-order aberrations, the constant increase of the primary and secondary spherical aberration with aging (P < .01) is caused by the spherical aberration growth of the anterior surface. Apart from these, only the vertical coma aberration of the posterior surface and the vertical trefoil aberrations of both the anterior and posterior surfaces showed a significantly positive correlation with aging (P < .05).

CONCLUSIONS

Corneal astigmatism showed a significant decrease with aging. Of the higher-order aberrations, primary and secondary spherical aberrations, vertical coma, and vertical trefoil significantly increase with age, whereas other higher-order aberrations show no correlation with aging.

Scheimpflug imaging in anterior megalophthalmos

We report an anterior megalophthalmos case with decreased corneal thickness and show the findings using Scheimpflug imaging. A 25-year-old male was diagnosed with anterior megalophthalmos. In both eyes, enlarged corneal length was measured. Beside a comparatively good visual acuity, a thin but clear cornea, a fairly deep anterior chamber, and central lens opacity were found. Scheimpflug images were taken using Pentacam HR. Scheimpflug-based imaging can provide us new data at the examination of this syndrome affecting the whole anterior segment.

Comparison of intraocular lens power prediction using immersion ultrasound and optical biometry with and without formula optimization

PURPOSE

Comparison of postoperative refraction results using ultrasound biometry with closed immersion shell and optical biometry.

PATIENTS AND METHOD

Three hundred and sixty-four eyes of 306 patients (age: 70.6 ± 12.8 years) underwent cataract surgery where intraocular lenses calculated by SRK/T formula were implanted. In 159 cases immersion ultrasonic biometry, in 205 eyes optical biometry was used. Differences between predicted and actual postoperative refractions were calculated both prior to and after optimization with the SRK/T formula, after which we analysed the similar data in the case of Holladay, Haigis, and Hoffer-Q formulas. Mean absolute error (MAE) and the percentage rate of patients within ±0.5 and ±1.0 D difference in the predicted error were calculated with these four formulas.

RESULTS

MAE was 0.5-0.7 D in cases of both methods with SRK/T, Holladay, and Hoffer-Q formula, but higher with Haigis formula. With no optimization, 60-65 % of the patients were under 0.5 D error in the immersion group (except for Haigis formula). Using the optical method, this value was slightly higher (62-67 %), however, in this case, Haigis formula also did not perform so well (45 %). Refraction results significantly improved with Holladay, Hoffer-Q, and Haigis formulas in both groups. The rate of patients under 0.5 D error increased to 65 % by the immersion technique, and up to 80 % by the optical one.

CONCLUSIONS

According to our results, optical biometry offers only slightly better outcomes compared to those of immersion shell with no optimized formulas. However, in case of new generation formulas with both methods, the optimization of IOL-constants give significantly better results.

Cell adhesion molecules in stromal corneal dystrophies

The aim of the present study was to investigate the expression pattern of different cell adhesion molecules in corneal stromal dystrophies. Fifteen corneal buttons from patients diagnosed with three different types of stromal corneal dystrophies and healthy corneas were investigated. Paraffin embedded sections were stained immunohistochemically with monoclonal antibodies against human intercellular adhesion molecule-1 (ICAM-1), endothelial selectin (E-selectin) and endothelial cadherin (E-cadherin) using the avidin-biotin-peroxidase-complex technique. The sections were compared to normal eye bank controls. In corneas from granular dystrophy patients ICAM-1 was expressed focally in epithelial cells and in keratocytes, and expressed diffusely in endothelial cells. In corneas from macular dystrophy patients diffuse epithelial staining was observed and the stromal and endothelial expression was found to be similar to that of granular dystrophy. In lattice dystrophy, only the epithelial cells and endothelium were intensively positive for ICAM-1. E-selectin was not present on any layer of the corneal specimens. E-cadherin was observed only in the epithelium of all three types of corneal dystrophies. Normal corneas did not express any of the investigated adhesion molecules. We found different expression patterns of adhesion molecules in corneas from stromal dystrophies. Our results suggest that adhesion molecules may be involved in the pathogenesis of corneal stromal dystrophies.

Assessment and reproducibility of anterior chamber depth measurement with anterior segment optical coherence tomography compared with immersion ultrasonography

PURPOSE

To measure anterior chamber depth (ACD) with an anterior segment optical coherence tomography (AS-OCT) and a standard ultrasonic (US) axial scan (A-scan) device using an immersion technique and to assess repeatability, reproducibility, and correlations of the measurements.

SETTING

Department of Ophthalmology, Medical Health and Science Center, University of Debrecen, Debrecen, Hungary.

METHODS

Sixty healthy eyes of 41 patients were enrolled in a study. The central ACD was measured 5 times with AS-OCT (Visante, Carl Zeiss Meditec) using its chamber tool and 5 times with a US A-scan device (UltraScan Imaging System, Alcon Laboratories) using an immersion method. The measurements were performed consecutively by 2 independent observers.

RESULTS

The mean ACD measured with AS-OCT was 3.12 mm +/- 0.33 (SD) by observer 1 and 3.11 +/- 0.33 mm by observer 2 (P = .78). The repeatability was 0.8% +/- 0.4% and 1.9% +/- 1.4%, respectively. The reproducibility was 0.23%. The reliability coefficient with AS-OCT was 99.6%. The mean ACD measured with immersion US A-scan was 2.98 +/- 0.33 mm by observer 1 and 2.95 +/- 0.34 mm by observer 2 (P = .68) . The repeatability was 6.4% +/- 3.8% by observer 1 and 8.5% +/- 4.9% by observer 2. The reproducibility was 0.88%. The reliability coefficient was 87.1% for US A-scan measurements. The difference between ACD values with AS-OCT and values with US A-scan was statistically significant (P = .02). The correlation (r) between AS-OCT and US A-scan was 0.732 (P<.0001) by observer 1 and 0.802 (P<.0001) by observer 2.

CONCLUSIONS

Anterior chamber measurements were significantly deeper with AS-OCT than with US immersion A-scan. Repeatability of ACD measurements was better with AS-OCT than with immersion US, and reproducibility was equal with the 2 methods.

Anterior chamber depth measurements in phakic and pseudophakic eyes: Pentacam versus ultrasound device

PURPOSE

To compare anterior chamber depth (ACD) measurements with a new optical device with those taken with a standard ultrasound (US) device in emmetropic phakic and pseudophakic eyes.

SETTING

Department of Ophthalmology, Medical Health and Science Center, University of Debrecen, Debrecen, Hungary.

METHODS

Forty-two phakic and 42 pseudophakic patients with normal axial lengths (mean 22.91 mm +/- 1.21 [SD]) were enrolled in the study. The ACD was measured 3 times with Scheimpflug-based Pentacam (Oculus) and then 3 times with a standard A-scan US device (AL-2000, Tomey). The data were then analyzed.

RESULTS

In the phakic group, the mean ACD was 2.87 +/- 0.4 mm with the Pentacam and 2.89 +/- 0.49 mm with ultrasound A-scan (US) (P = .84). In the pseudophakic group, the mean ACD was 3.41 +/- 0.28 mm and 3.97 +/- 0.45 mm, respectively (P < .001). The correlation between measurements was significant in both the phakic and pseudophakic groups (r = .547/P < .001 and r = .404/P = .01, respectively).

CONCLUSIONS

In phakic eyes, ACD measured with the Pentacam and with US was the same. However, in pseudophakic eyes, the difference was significantly lower when the ACD was measured with the Pentacam. Therefore, in pseudophakic patients, further evaluation of ACD data with the Scheimpflug-based system is necessary.

Extracellular matrix molecules and their possible roles in the regeneration of frog nervous system

Recent biochemical and histochemical analyses explored different components of the extracellular matrix (ECM) in the nervous system, and either permissive or non-permissive roles in neuronal development and regeneration were suggested. The aim of this study was to detect the distribution pattern of a few of these molecules in the nervous system of intact frogs and during nerve regeneration. The hyaluronan (HA) and tenascin C reactions were negative in the peripheral nerves, but appeared in their entry zones. In the CNS, different populations of neurons were surrounded with HA and tenascin C-positive material, forming a perineuronal net (PN). The phosphacan reaction was weakly positive in the PNS, and a moderate intensity was detected in the entry zone and in the PN. Laminin and fibronectin immunoreactivity was strong in the PNS, but laminin could not be detected in the CNS. In animals with cut and regenerating vestibulocochlear nerve, the distribution of the ECM molecules in the CNS and PNS characteristically changed from that of the normal pattern. Our results showed a non-homogenous distribution of ECM components in the frog nervous system that could be associated with their different roles in physiological and pathological processes.

Impaired wound healing in factor XIII deficient mice

Factor XIII that stabilizes fibrin clots in the final stages of blood coagulation also participates in wound healing, as can be inferred from a delay in wound repair in some patients with inherited FXIII deficiency. In this study we evaluated the effect of FXIII on wound healing in FXIII-deficient mice. Three groups of mice (n = 10) were employed: control group, FXIII-deficient group and FXIII-deficient group treated with FXIII concentrate. Excisional wounds were left unsutured and undressed, and mice were followed for eleven days. FXIII-deficient mice exhibited impaired wound healing as has been demonstrated by 15%, 27% and 27% decrease in percentage of wound closure on day 4, 8 and 11, respectively. On day 11 complete healing was observed in control (100% closure), 73.23% in FXIII-deficient and 90.06% in FXIII deficient/FXIII-treated groups (p = 0.007 by ANOVA and p = 0.001 by t-test between control and FXIII-deficient groups). Scoring system representing maturation rate of the wounds showed that the scores for the control, FXIII-deficient and FXIII deficient/FXIII treated groups were 94.9 +/- 4.7, 61.5 +/- 14.5 and 94.5 +/- 6.4, respectively (p < 0.001 by ANOVA). Histological analysis of the lesions performed at day 11 disclosed delayed reepithelization and necrotized fissure in FXIII-deficient mice and normal healing in FXIII-deficient/FXIII-treated mice. The findings of this study confirm that in FXIII-deficient mice wound healing is delayed and the cellular and tissue defects can be corrected by treatment with FXIII, providing evidence for the essential role of FXIII in wound repair and remodeling.

Autologous Osteochondral Grafting (Mosaic Arthroplasty) for Treatment of Subchondral Cystic Lesions in the Equine Stifle and Fetlock Joints

OBJECTIVE

To describe treatment of equine subchondral bone cysts (SBCs) by reconstruction of the articular surface with osteochondral grafts.

STUDY DESIGN

Case series of horses with SBCs unresponsive to conservative therapy.

ANIMALS

Eleven horses (1-12 years).

METHODS

SBCs were identified in 4 locations: medial femoral condyle (5 horses), lateral femoral condyle (1), distal epiphysis of the metacarpus (4), or metatarsus (1). Osteochondral autograft transplantation (mosaic arthroplasty) was performed, taking grafts from the abaxial border of the medial femoral trochlea of the unaffected limb. Graft implantation was achieved through a small arthrotomy or by arthroscopy depending on SBC location.

RESULTS

All horses improved postoperatively; 10 horses had successful outcomes with radiographic evidence of successful graft incorporation and 7 returned to a previous or higher activity level. On follow-up arthroscopy (5 horses) there was successful reconstitution of a functional gliding surface. One horse had delayed incorporation of a graft because of a technical error but became sound. One horse had recurrence after 4 years of work and soundness. One stallion was used for breeding and light riding because of medial meniscal injuries on the same limb.

CONCLUSIONS

Implantation of osteochondral grafts should be considered for SBC when conservative management has not improved lameness and there is a risk of further joint injury and degeneration.

CLINICAL RELEVANCE

Mosaic arthroplasty should be considered for treatment of subchondral bone cysts of the femoral condyle and distal articular surface of the metacarpus/tarsus in horses that are refractory to non-surgical management.

Evaluation of corneal flap dimensions and cut quality using the SKBM automated microkeratome

PURPOSE

To evaluate flap dimensions and cut quality with repeated blade use of the automated Summit Krumeich-Barraquer microkeratome (SKBM [LadarVision]).

SETTING

Department of Ophthalmology, University Erlangen-Nuremberg, Erlangen, Germany.

METHODS

The SKBM (160 microm plate, intended flap diameter 9.0 mm) was used to perform a corneal hinged flap in 35 pig cadaver eyes. Seven blades were reused 5 times each. The flap diameter was measured by planimetry, and the thickness was assessed by ultrasonic pachymetry. Scanning electron microscopy (SEM) of blades and stromal beds was performed.

RESULTS

With single use of the blade, the mean central flap thickness was 145 microm +/- 25 (SD). The vertical/horizontal flap diameter was 9.0 +/- 0.03 mm/8.6 +/- 0.03 mm. No thickness gradient was observed from the incision (138 +/- 31 microm) to the flap hinge (130 +/- 30 microm). If the blade was used more than 2 times, the flap was thinner at the incision (157 +/- 34 microm versus 124 +/- 20 microm; P =.003) and the hinge (143 +/- 24 microm versus 122 +/- 31 microm; P =.04), but the central thickness remained unchanged. With multiple use of the blade, SEM analysis showed increasing cut irregularity, more tissue remnants on the blade surface, and a progression in blade irregularities (up to 9.3 microm).

CONCLUSIONS

Reproducible flap size and thickness can be obtained with single use of stainless steel blades in the SKBM. With multiple use, the quality of the blades and the stromal bed deteriorates and the peripheral thickness of the flaps decreases. Thus, single use of blades is recommended.

Sur le comportement des mastocytes chez le rat en conditions d'hypo- et d'hypervitaminose A

The behaviour of rat mast cells under conditions of high and low vitamin A

The authors have studied the mast cells in normal rats and in rats under hypo- and hypervitaminosis A. The main results of their studies are: (a) in the skin (dermis), in the case of A hypervitaminosis, there is a significant rise in the number of the mastocytes with swelling and dcgranulation; (b) in lung and bone marrow, the number of mastocytes is increased under hypovitaminosis A and there is also blood congestion and lipomatosis of bone marrow.

The authors give an interpretation of their results.