Corneal oedemas: diagnosis and surgical planning with ultrasound biomicroscopy

[Intraoperative optical coherence tomography in corneal and glaucoma surgical procedures]

BACKGROUND

Optical coherence tomography (OCT) is the clinical gold standard for anterior and posterior segment imaging. Since OCT devices have been integrated into surgical microscopes, this technique is also available intraoperatively in anterior segment surgery. OCT is well established in imaging very thin or transparent structures as they appear in corneal or glaucoma surgery. Therefore, intraoperative OCT can deliver important information for the surgeon which is superior to the normal surgical microscope.

OBJECTIVES

In the present work, an overview about the opportunities of intraoperative OCT in cornea and glaucoma surgery are presented.

MATERIAL AND METHODS

The recent literature (PubMed) and our own experience at the Center for Ophthalmology, University Hospital of Cologne are analysed.

RESULTS

Intraoperative OCT enables real-time imaging during corneal and glaucoma surgery. Several clinical studies exist, indicating its benefit, e. g. in DMEK, DALK, DSAEK, Boston Keratoprosthesis, canaloplasty or trabectome surgery. Several structures, not visible in the surgical microscope, can be visualized using intraoperative OCT.

CONCLUSIONS

As a real-time and high-resolution imaging device, intraoperative online OCT delivers additional information in glaucoma and corneal surgery, compared to the normal operating microscope. Nonetheless one of the main problems is the shadowing produced by surgical instruments. Today the main limitation is the lack of randomized-controlled clinical trials, evaluating the benefit of microscope-integrated intraoperative OCT, compared to the microscope.

High resolution imaging of the equine cornea using the DUB®-SkinScanner v3.9

OBJECTIVE

The aim was to describe the use of the DUB®-SkinScanner v3.9 (taberna pro medicum GmbH, Lueneburg, Germany) for the examination of the equine cornea.

MATERIAL AND METHODS

Using the DUB^®-SkinScanner v3.9 various pathological corneal conditions were pictured in the A- and B-mode at a frequency of 22 and/or 50 MHz in nine eyes of eight horses. Scans were obtained from standing horses or from horses under general anesthesia non-related to image acquisition.

RESULTS

The examination allowed real time imaging and measurement of the equine cornea in vivo. Compared to slit-lamp biomicroscopy additional information was obtained in seven of nine eyes regarding the corneal thickness, in four of nine eyes regarding the epithelium, in five of nine eyes regarding the stroma and in five of nine eyes regarding the endothelium.

CONCLUSION AND CLINICAL RELEVANCE

The DUB^®-SkinScanner v3.9 is a valuable high-resolution imaging tool for the evaluation of the equine cornea under practice conditions. The image acquisition does not depend on corneal transparency and provides additional diagnostic information to the standard slit-lamp biomicroscopy.

Comparison of high-resolution Scheimpflug and high-frequency ultrasound biomicroscopy to anterior-segment OCT corneal thickness measurements

Background

The purpose of this study was to compare and correlate central corneal thickness in healthy, nonoperated eyes with three advanced anterior-segment imaging systems: a high-resolution Scheimpflug tomography camera (Oculyzer II), a spectral-domain anterior-segment optical coherence tomography (AS-OCT) system, and a high-frequency ultrasound biomicroscopy (HF-UBM) system.

Methods

Fifty eyes randomly selected from 50 patients were included in the study. Inclusion criteria were healthy, nonoperated eyes examined consecutively by the same examiner. Corneal imaging was performed by three different methods, ie, Oculyzer II, spectral-domain AS-OCT, and FH-UBM. Central corneal thickness measurements were compared using scatter diagrams, Bland-Altman plots (with bias and 95% confidence intervals), and two-paired analysis.

Results

The coefficient of determination (r²) between the Oculyzer II and AS-OCT measurements was 0.895. Likewise, the coefficient was 0.893 between the Oculyzer II and HF-UBM and 0.830 between the AS-OCT and HF-UBM. The trend line coefficients of linearity were 0.925 between the Oculyzer II and the AS-OCT, 1.006 between the Oculyzer II and HF-UBM, and 0.841 between the AS-OCT and HF-UBM. The differences in average corneal thickness between the three pairs of CCT measurements were −6.86 μm between the Oculyzer II and HF-UBM, −12.20 μm between the AS-OCT and Oculyzer II, and +19.06 μm between the HF-UBM and AS-OCT.

Conclusion

The three methods used for corneal thickness measurement are highly correlated. Compared with the Scheimplug and ultrasound devices, the AS-OCT appears to report a more accurate, but overally thinner corneal pachymetry.

Clinical features of anterior segment dysgenesis associated with congenital corneal opacities

PURPOSE

Anterior segment dysgenesis is one of the main causes of congenital corneal opacities. In this study, we investigated the clinical features and visual outcomes of patients with anterior segment dysgenesis in a large number of cases.

METHODS

The medical records of patients with congenital corneal opacities in relation to anterior segment dysgenesis seen in the National Center for Child Health and Development, Japan, between April 2002 and October 2009, were retrospectively studied.

RESULTS

Records of 220 eyes of 139 patients were reviewed. Mean follow-up period was 5 years. Clinical diagnoses were Peters anomaly (72.7%), anterior staphyloma (11.4%), Rieger anomaly (7.7%), sclerocornea (6.4%), and others (1.8%). Visual acuity was measured in 61 patients. The best-corrected visual acuity in the better eye of bilaterally involved patients was 20/60 to 20/1000 (low vision according to the International Classification of Diseases, Ninth Revision, Clinical Modification) in 43.2% and less than 20/1000 (legally blind) in 24.3%. Fundus examination was performed in 82 eyes, and disorders were seen in 12 (12 of 82; 14.6%). Systemic abnormalities were present in 35 patients (35 of 139; 25.2%); a family history was present in 5 patients (5 of 139; 3.6%). Of the 160 eyes of 109 patients with Peters anomaly, 51 patients (51 of 109; 46.8%) had bilateral Peters anomaly, 30 (30 of 109; 27.5%) had fellow eyes that were normal, and 28 (28 of 109, 25.7%) showed other abnormal ocular findings in the fellow eye.

CONCLUSIONS

Anterior segment dysgenesis shows diverse clinical features, various severities of corneal opacities, and visual outcomes. Further understanding of the disease as an abnormality during embryogenesis and neural crest cell differentiations may be required.

High-resolution ultrasound imaging of the eye - a review

This report summarizes the physics, technology and clinical application of ultrasound biomicroscopy (UBM) of the eye, in which frequencies of 35 MHz and above provide over a threefold improvement in resolution compared with conventional ophthalmic ultrasound systems. UBM allows imaging of anatomy and pathology involving the anterior segment, including regions obscured by overlying optically opaque anatomic or pathologic structures. UBM provides diagnostically significant information in conditions such as glaucoma, cysts and neoplasms, trauma and foreign bodies. UBM also can provide crucial biometric information regarding anterior segment structures, including the cornea and its constituent layers and the anterior and posterior chambers. Although UBM has now been in use for over 15 years, new technologies, including transducer arrays, pulse encoding and combination of ultrasound with light, offer the potential for significant advances in high-resolution diagnostic imaging of the eye.

Ultrasound biomicroscopy and Scheimpflug photography of angle-supported phakic intraocular lens for high myopia

PURPOSE

To evaluate the equivalence of Scheimpflug photography (SP) and ultrasound biomicroscopy (UBM) in determining corneal epithelium-intraocular lens (IOL) and border IOL-iris distances.

SETTING

Universität Erlangen-Nuremberg, Erlangen, Germany.

METHODS

In 26 eyes of 17 patients who had a NuVita MA20 angle-supported anterior chamber intraocular lens (Chiron-Domilens), SP and UBM were used to evaluate the distance between the endothelium and the anterior IOL face in central and peripheral regions (12 o'clock and 6 o'clock positions) and between the border of the anterior IOL face and the iris. The Wilcoxon test was used for statistical analysis.

RESULTS

The mean central endothelium-anterior IOL face distance was 2.01 mm and 2.00 mm by SP and UBM, respectively. The mean peripheral endothelium-anterior IOL border distance was 1.28 mm and 1.58 mm, respectively, and the mean peripheral anterior IOL face-iris distance, 0.89 mm and 0.75 mm, respectively.

CONCLUSIONS

The difference between the 2 methods in the central endothelium-anterior IOL face distance was not significant (methods were equivalent), but the difference in the peripheral endothelium-anterior IOL face distance was. This may be the result of difficulty in obtaining the exact transition point between the IOL and the haptics by SP examination. The difference between the 2 methods in the IOL border-iris distance was also significant because of the irregularity of the iris surface; therefore, measurements were performed at different sites along this structure. The significant differences in the peripheral endothelium-IOL and IOL border-iris distances indicate that although both methods are useful, they are not equivalent.

Clinicopathological correlation of congenital corneal opacification using ultrasound biomicroscopy

AIM

To investigate the correlation between clinical, high frequency ultrasound biomicroscopy (UBM) and, where possible, histological findings in cases of congenital corneal opacification presenting to the departments of ophthalmology, Great Ormond Street Hospital for Children, London, and the Hospital for Sick Children, Toronto, Canada.

METHOD

22 eyes of 13 children (age range 3-225 days) with congenitally opaque corneas were examined. UBM was performed using the ultrasound biomicroscope (Allergan-Humphrey). All eyes underwent penetrating keratoplasties (PKP) except five. The host corneas were all sent for histological examination.

RESULTS

The final diagnosis in our series was Peters' anomaly in nine cases (70%), corneal dystrophy in two cases (15%), and sclerocornea in two cases (15%). The UBM findings changed the clinical diagnosis in five cases (38%). In these five cases histology was available in four and confirmed the UBM diagnosis in each case. In no case of the 13 where histology was available did it contradict the UBM findings. In two cases a hypoechoic region in the anterior stroma was seen on UBM which correlated histologically with absent Bowman's layer and oedema. In two cases UBM revealed aniridia and in one, congenital aphakia, which was not apparent clinically.

CONCLUSION

UBM examination is not only very useful in evaluating the clinical diagnosis in congenital corneal opacification, it also acts as a preoperative guide in cases undergoing PKP by detecting keratolenticular and iridocorneal adhesions and other ocular abnormalities such as aniridia and congenital aphakia. In all cases where PKP was performed the UBM diagnosis was confirmed histologically. The clinical diagnosis was incorrect in five cases. This has important implications in studies of phenotype/genotype correlation of congenital corneal opacification.