En-face Optical Coherence Tomography as a Novel Tool for Exploring the Ocular Surface: A Pilot Comparative Study to Conventional B-Scans and in Vivo Confocal Microscopy

doi:10.1016/j.jtos.2014.02.006

The Ocular Surface

Volume 12, Issue 4, October 2014, Pages 285-306

https://doi.org/10.1016/j.jtos.2014.02.006 Get rights and content

Abstract

Purpose

To explore the potential of spectral-domain optical coherence tomography (SD-OCT) using the en-face technology for the imaging of ocular surface diseases and to correlate the findings with in vivo confocal microscopy (IVCM) images.

Patients and methods

113 eyes of 75 subjects with various ocular surface diseases were investigated with the RTVue^® anterior-segment en face OCT. En face OCT images were compared to B-scan OCT and IVCM images.

Results

Patients with corneal dystrophies, corneal deposits, keratitis, pterygium, conjunctivochalasis, or ocular surface squamous neoplasia and patients who underwent lamellar corneal surgeries were included. En-face OCT images showed ocular surface tissue changes that were not discernible using conventional B-scan OCT. Nevertheless, there was a good correlation with IVCM analysis. Compared with IVCM, the major advantages of en-face OCT included easy operation and rapid image acquisition, with minimal operator experience required. In addition, the non-contact method avoided patient discomfort and external pressure on the globe, which was especially useful in patients with corneal dystrophies, ulcers, or corneal abscesses. Although the resolution of en-face OCT was lower than that of IVCM, it allowed useful overall visualization of corneal lesions due to the larger areas analyzed.

Conclusion

En-face SD-OCT is a novel, valuable tool to assess a wide variety of ocular surface diseases. It can provide additional information and new insight into different ocular surface conditions with no corneal contact.

Introduction

Optical coherence tomography (OCT) was initially developed in 1991 by Huang et al at the Massachusetts Institute of Technology (Cambridge, MA, USA).¹ It was first used for analyzing the cornea and anterior segment of the human eye in 1994.² Since then, anterior-segment OCT (AS-OCT) has rapidly become a reliable tool for anterior segment assessment.3, 4, 5, 6 Recently, the development of spectral-domain (SD) technology dramatically improved imaging speeds.6, 7, 8, 9, 10 Among all the SD devices, the RTVue^® is the first and the only SD-OCT system to be approved by the U.S. Food and Drug Administration for both corneal and retinal imaging.¹¹Its high speed and resolution allow the acquisition of three-dimensional (3D) volumes that make possible the reconstruction of coronal sections, also called C-scans or en-face OCT.12, 13The C-scans are oriented in a frontal plane, perpendicular to the optical axis of the eye. They give an instant overview of tissue changes as a two-dimensional transversal slice at any defined depth.

The aim of our study was to investigate the en-face OCT features of a large variety of ocular surface diseases. The observations using this new imaging technique were also compared and correlated with conventional OCT B-scans, in vivo confocal microscopy (IVCM), and previously reported histopathological findings.

Section snippets

Patients and Methods

This observational case series was conducted between November 2012 and June 2013 at the Quinze-Vingts National Ophthalmology Hospital, Paris, France. Written informed consent was obtained and documented from all participants before OCT and IVCM were performed. The study adhered to the tenets of the Declaration of Helsinki and was approved by the Ile-de-France Institutional Review Board for Research on Human Subjects (CCP 5, N° 10793).

Results

In total, 113 eyes of 75 subjects with various anterior segment conditions were analyzed by anterior-segment SD-OCT combined with IVCM analysis. Fifty-eight were right eyes and 55 were left eyes. The male-to-female ratio was 33:42. Age ranged from 9 to 80 years, with a mean age of 47.4 ± 19.43 years. Table 1 summarizes the characteristics of the subjects included and the characteristic features investigated by en-face OCT scanning. We detailed the different pathologies as shown below.

Discussion

Over the past two decades, knowledge of ocular surface diseases has greatly expanded through the use of AS-OCT and IVCM. Currently, these imaging modalities are widely used in clinical practices to explore the ocular anterior-segment pathologies with their proper technical limits.13, 21, 22, 23, 24, 25, 26, 27 While the IVCM is a contact technique that provides data on a cellular level, the AS-OCT only provides cross-sectional anatomical images.²⁸ En-face OCT is a novel imaging modality derived

Conclusion

This study shows that en-face OCT is a promising adjunctive tool for assessing a wide variety of ocular surface conditions. It can noninvasively provide additional information not readily available with conventional imaging techniques. This capability has the potential to provide greater insight into the understanding and follow-up of ocular surface conditions. With continued improvements to the technology, future development of en-face ultra-high-resolution (UHR) OCT will improve resolution

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Cited by (18)

Evaluation of pterygium severity with en face anterior segment optical coherence tomography and correlations with in vivo confocal microscopy
2021, Journal Francais d'Ophtalmologie
Citation Excerpt :
These coronal sections, also called C-scan, provide a new way to represent and analyze anterior segment tissues in vivo. In a preliminary study, our group showed EF-OCT images of pterygium [17]. The study we present here aim to confirm the usefulness of EF-OCT in assessing pterygium severity and correlate IVCM findings.
To describe en face anterior segment optical coherence tomography (EF-OCT) characteristics of pterygia and their correlation with in vivo confocal microscopy (IVCM).
In this observational case series, we prospectively included 21 eyes of 17 subjects with pterygium. All subjects underwent detailed ophthalmic examination, anterior segment photography, an ocular surface disease index (OSDI) questionnaire, IVCM, and EF-OCT. Eyes were divided into two groups according to pterygium severity (Modified Pterygium Classification System) and OSDI score. EF-OCT images for both groups were analyzed for surface area of Fuchs Patches (FP). The IVCM activity score was based on the number of inflammatory cells, blood vessels, activated keratocytes and the appearance of the cornea/pterygium at the head of the pterygium. The correlations between EF-OCT and IVCM images were then analyzed and compared in both groups.
EF-OCT permits clear visualization and evaluation of FPs and the border between the pterygium and the adjacent cornea. The severe pterygium group was characterized by irregular borders and larger FPs (0.13 ± 0.06 mm² versus 0.06 ± 0.02 mm² respectively) (P = 0.003). The mean IVCM activity score was 2.36 ± 0.81 in the severe pterygium group and 1.2 ± 0.42 in the mild pterygium group (P = 0.0013). There was a positive correlation between FP surface area and IVCM activity score. A larger FP surface area was associated with a higher activity score on IVCM.
EF-OCT allows good evaluation of pterygium extension, borders and FP surface area. EF-OCT analysis of pterygium could represent a simple, non-invasive and reproducible method to evaluate pterygium severity and activity.
Décrire les caractéristiques des ptérygions sur l’imagerie « en face » en tomographie par cohérence optique du segment antérieur (EF-OCT) et leur corrélation avec la microscopie confocale in vivo (IVCM).
Dans cette série de cas, nous avons inclus de manière prospective 21 yeux de 17 sujets avec un ptérygion. Tous les sujets ont bénéficié d’un examen ophtalmologique détaillé incluant photographie du segment antérieur, évaluation de l’ocular surface disease index (OSDI), imagerie IVCM et EF-OCT. Les ptérygions étaient répartis en deux groupes en fonction du score de gravité (Modified Pterygium Classification System) et du score OSDI. Les images EF-OCT ont été analysées dans les deux groupes avec une mesure de la surface des patchs de Fuchs (FP). La corrélation entre les images EF-OCT et le score d’activité IVCM a été analysée dans les deux groupes.
L’EF-OCT permet une visualisation précise des FP ainsi que des limites entre le ptérygion et la cornée adjacente. Le groupe de ptérygions sévères était caractérisé par des limites irrégulières et une surface des FP plus grande (0,13 ± 0,06 mm² contre 0,06 ± 0,02 mm²) (p = 0,003). Le score d’activité moyen de l’IVCM était de 2,36 ± 0,81 dans le groupe ptérygion sévère et 1,2 ± 0,42 dans le groupe ptérygion modéré (p = 0,0013). Il y avait une corrélation positive entre la surface des FP et le score d’activité de l’IVCM. Une plus grande surface de PF était associée à un score d’activité plus élevé sur l’IVCM.
L’EF-OCT permet une bonne évaluation du ptérygion, de ses limites et de la surface des FP. L’analyse EF-OCT du ptérygion constitue une méthode simple, non invasive et reproductible pour évaluer la gravité et l’activité du ptérygion.
Quantitative evaluation of infectious keratitis by anterior segment optical coherence tomography
2020, Journal Francais d'Ophtalmologie
L’évaluation des kératites infectieuses, en pratique clinique, est largement dominée par l’examen biomicroscopique qui présente des limites quant à l’appréciation de la profondeur de l’infiltrat et l’estimation de l’épaisseur exacte de l’œdème ou de l’amincissement cornéens. L’objectif de notre étude est d’évaluer quantitativement la réponse inflammatoire cornéenne au traitement délivré aux kératites infectieuses, à l’aide d’un dispositif d’OCT-SA. Nous avons mené une étude prospective, au service d’ophtalmologie de l’hôpital militaire Mohammed V de Rabat entre novembre 2017 et mai 2019, chez 32 patients présentant une kératite infectieuse. Un protocole d’acquisition standardisé a été utilisé. L’épaisseur de l’infiltrat quand il a eu lieu et de la cornée, au niveau de la zone d’amincissement éventuelle et de la zone oedématiée qui les entoure, a été mesuré. Les différentes épaisseurs ont diminué progressivement au cours du suivi, ce qui a permis d’apporter des preuves objectives sur la guérison de ces kératites dès la phase précoce du traitement. L’amélioration de l’épaisseur de la cornée oedématiée et de la cornée amincie a été plus rapide à la phase initiale. L’OCT-SA permettrait, à côté de l’examen à la lampe à fente, un meilleur suivi des patients présentant une kératite infectieuse.
The clinical evaluation of infectious keratitis takes place largely through biomicroscopic examination, which presents limitations in the evaluation of the depth of the infiltrate and the exact thickness of the cornea, whether edematous or thinned. In this study, we aim to quantify the human corneal inflammatory response in treated infectious keratitis by anterior segment optical coherence tomography (AS-OCT). Patients with infectious keratitis were recruited prospectively in the ophthalmology department of the military hospital of Rabat between November 2017 and May 2019. Over the study period, 32 patients were included. A standardized scanning protocol was used. The thickness of the infiltrate, when present, and corneal thickness in any area of thinning and any surrounding edematous areas were measured. The various thicknesses gradually decreased over the course of follow-up, providing objective evidence of therapeutic efficacy in the early stages. Improvement in corneal edema and thinning was faster in the early stage. AS-OCT scanning can be used along with slit lamp examination to quantify and objectively follow infectious keratitis.
Imaging of corneal dystrophies: Correlations between en face anterior segment OCT and in vivo confocal microscopy
2015, Journal Francais d'Ophtalmologie
Étudier l’apport de l’OCT en face dans l’évaluation des dystrophies cornéennes et décrire les corrélations avec la microscopie confocale in vivo (IVCM).
Trente-deux yeux de 16 patients atteints de 4 types de dystrophies cornéennes (dystrophie de Cogan, de Fuchs, de Reis-Bücklers et Crocodile Shagreen) ont été inclus dans cette étude. Tous les patients ont bénéficié d’une analyse de la cornée en OCT grâce à des coupes axiales et des reconstructions en face. Les images ont été ensuite confrontées aux aspects observés en IVCM.
Les images d’OCT en face offraient des informations supplémentaires sur l’aspect, la taille et la profondeur des altérations tissulaires au cours des dystrophies cornéennes. Les images obtenues en coupes frontales complétaient ainsi les traditionnelles coupes axiales obtenues en OCT et étaient bien corrélées avec les aspects observés en IVCM. Malgré une résolution d’image inférieure à celle de l’IVCM, l’OCT en face présentait l’avantage d’être non contact et d’offrir une surface d’analyse cornéenne plus grande.
L’OCT en face apporte des éléments sémiologiques utiles à l’évaluation des dystrophies cornéennes et ouvre des perspectives intéressantes pour l’exploration des affections du segment antérieur.
To evaluate the usefulness of en face Optical Coherence Tomography (OCT) for evaluation of corneal dystrophies and to describe correlations with in vivo confocal microscopy (IVCM).
Thirty-two eyes of 16 patients with 4 types of corneal dystrophies (epithelial basement membrane dystrophy, Fuchs dystrophy, Reis-Bücklers corneal dystrophy and Crocodile Shagreen dystrophy) were enrolled in this study. Axial and reconstructed en face scans were acquired using OCT. Images were then correlated to IVCM findings.
En face OCT provided new insights into the structure, size and depth of corneal tissue alterations in various corneal dystrophies. OCT en face images were well correlated with IVCM features. Despite lower resolution than IVCM, en face OCT offers the advantages of being non-invasive and allowing the analysis of larger corneal areas.
En face OCT provides useful new information in corneal dystrophies. This imaging technique will probably increase in popularity in the near future for the assessment of various anterior segment diseases.
Conjunctivochalasis: a systematic review
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Citation Excerpt :
Increased tear film osmolarity may be found in severe cases of CCH, especially in association with abnormal tear film break-up time and positive ocular surface vital staining.23 AS-OCT has recently been used to provide a precise quantitative measurement of CCH and its grading (Fig. 3).28,71,76 Using a Fourier Domain RTVue-100 AS-OCT (Optovue Inc, Fremont, California), Gumus and colleagues performed vertical cross-sectional scans of the conjunctiva.28,29
Conjunctivochalasis (CCH) is a conjunctival condition characterized by loose, redundant conjunctival folds, most typically in the inferior bulbar conjunctiva of both eyes. Although CCH is a common cause of ocular irritation and discomfort, especially in the elderly, it is often overlooked in clinical practice. CCH may be associated with various ocular and nonocular conditions; however, the most important risk factor is aging. Although often asymptomatic, CCH may cause symptoms related to tear film instability and/or delayed tear clearance. Pathogenesis of CCH remains largely unknown but may involve different elements such as aged conjunctiva, unstable tear film, mechanical friction, ocular surface inflammation, and delayed tear clearance. Contradictory results have been reported on histopathologic changes in CCH, with some studies showing a normal microscopic structure. For symptomatic CCH, medical treatment may include lubrication and anti-inflammatory medications. For symptomatic patients who fail to respond to medical treatment, a surgical procedure may be considered. Although various surgical procedures have been used for CCH, more often, it consists of conjunctival cauterization or excision of the redundant conjunctiva, with or without amniotic membrane transplantation.
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: Supported by: Unrestricted grant from the Center of Clinical Investigations 503 INSERM (National Institute of Health and Medical Research), Quinze-Vingts National Ophthalmology Hospital, Paris, France.

: The authors have no proprietary or commercial interests in any concept or product discussed in this article.

: Single-copy reprint requests to Prof. Christophe Baudouin (address below).

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Innovative Techniques and TechnologyEn-face Optical Coherence Tomography as a Novel Tool for Exploring the Ocular Surface: A Pilot Comparative Study to Conventional B-Scans and in Vivo Confocal Microscopy

Abstract

Purpose

Patients and methods

Results

Conclusion

Introduction

Section snippets

Patients and Methods

Results

Discussion

Conclusion

Prog Retin Eye Res

Surv Ophthalmol

Ocul Surf

Ocul Surf

Ocul Surf

Ophthalmology

Ocul Surf

Ocul Surf

J Fr Ophtalmol

Ocul Surf

Ophthalmology

Ophthalmology

Am J Ophthalmol

J Fr Ophtalmol

J Fr Ophtalmol

Optical coherence tomography

Science

Micrometer-scale resolution imaging of the anterior eye in vivo with optical coherence tomography

Arch Ophthalmol

Longitudinal changes in anterior segment parameters after laser peripheral iridotomy assessed by anterior segment optical coherence tomography

Invest Ophthalmol Vis Sci

Deep sclerectomy versus trabeculectomy: a morphological study with anterior segment optical coherence tomography

Br J Ophthalmol

Tear meniscus evaluation by anterior segment swept-source optical coherence tomography

Am J Ophthalmol

Clinical and research applications of anterior segment optical coherence tomography – a review

Clin Experiment Ophthalmol

SD-OCT analysis of regional epithelial thickness profiles in keratoconus, postoperative corneal ectasia, and normal eyes

J Refract Surg

Imaging of the iridocorneal angle with the RTVue spectral domain optical coherence tomography

Invest Ophthalmol Vis Sci

Evaluation of corneal epithelial healing under contact lens with spectral-domain anterior segment optical coherence tomography (SD-OCT)

Open Ophthalmol J

High-definition imaging of trabeculectomy blebs using spectral domain optical coherence tomography adapted for the anterior segment

Clin Experiment Ophthalmol

Identifying early recurrence of choroidal neovascularization during treatment with ranibizumab using C-scan

Eur J Ophthalmol

Innovative Techniques and Technology
En-face Optical Coherence Tomography as a Novel Tool for Exploring the Ocular Surface: A Pilot Comparative Study to Conventional B-Scans and in Vivo Confocal Microscopy