Since the early nineties ultrasound biomicroscopy (UBM) has been used for the imaging of the anterior eye segment and was soon discovered to be useful in the evaluation of superficial tumors. Anterior segment optical coherence tomography (AS-OCT) became available in the 21st century. One of the first series on the use of OCT in the evaluation of conjunctival tumors was published by Buchwald et al., in 2003 [
Corneal and conjunctival tumors can be visualized by AS-OCT and UBM, two noninvasive imaging techniques. Hereby, tumor thickness and internal characteristics and extension in depth and size and shape can be measured. Several small series have been published, evaluating the use and the quality of AS-OCT or UBM in assessing these tumors. It is still not clear which technique to use in certain tumor types. We therefore conducted a literature search in order to find an answer to the following question: how accurate are AS-OCT and UBM in determining tumor margins and tumor depth of conjunctival and corneal tumors and can they provide additional information guiding the diagnosis?
AS-OCT is an examination technique that uses reflected light waves in order to reconstruct a cross section of the examined tissue. Time-domain OCT measures the electromagnetic radiation in function of the time. This investigation can make up to 400 axial scans per second and has an axial resolution of 8–10
UBM is an examination technique that uses sound waves to analyze the structures as in the classic ultrasound investigation. However, in UBM a higher frequency is used which consequently allows more detail but less penetration into the tissue [
We performed a specific literature search of peer reviewed published journal articles in the following stages.
The flow diagram of the literature search is shown in Figure
Flow diagram of literature search.
We analyzed 14 papers: 6 studies on UBM, 6 on OCT, and 2 studies that compared the two imaging techniques.
All studies are listed in Tables
Articles using UBM in conjunctival and corneal tumors.
Author, year | Study | Number of patients | Imaging technique | Aim | Tumor type | Results | Conclusion |
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Lanzl et al., 1998 | The role of ultrasound biomicroscopy in surgical planning for limbal dermoids—study design not given | 2 | UBM (50 MHz) | To investigate the use of ultrasound biomicroscopy (UBM) examination for surgical planning in limbal dermoids | Infantile limbal dermoid | | |
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Grant and Azar, 1999 | Ultrasound biomicroscopy in the diagnosis and management of limbal dermoid—study design not given | 1 | UBM (type of probe not mentioned) | To report the use of ultrasound biomicroscopy in the diagnosis and management of limbal dermoid | Limbal dermoid | Clinical examination, ultrasound biomicroscopy, biopsy confirmed the diagnosis of limbal dermoid | |
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Hoops et al., 2001 | Preoperative evaluation of limbal dermoids using high resolution biomicroscopy—retrospective analysis | 8 | High resolution biomicroscopy (50 MHz) | To assess whether ultrasound biomicroscopy (UBM) can detect the corneal depth of penetration of dermoids which could improve planning of surgery | Limbal dermoids | (i) 7/8: UBM showed a more reflective and predominantly homogeneous lesion compared with the unaffected corneal stroma, so that the lateral margins of the lesion could be clearly identified | |
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Buchwald et al., 2003 | Ultrasound biomicroscopy of conjunctival lesions—prospective study | 28 | UBM (30 MHz) | To determine the value of UBM in the diagnosis of conjunctival lesions | 28 conjunctival lesions: Compound nevus (8/28), cysts (6/28), inflammatory processes (3/28), granulomatous processes (2/28), lymphomas (2/28), foreign bodies (2/28), pterygium (2/28), malignant melanoma (1/28), primary acquired melanosis (1/28), conjunctival amyloidosis (1/28) | | |
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Lin et al., 2004 | Ultrasound Biomicroscopy in Pigmented Conjunctival Cystic Nevi—study design not given | 2 | UBM (type of probe not mentioned) | To report the use of UBM in the clinical diagnosis and management of pigmented conjunctival cystic nevi | 2 conjunctival lesions: raised melanocytic lesions localized on the conjunctiva characterised by rapid growth; they were suspected to be inflamed juvenile conjunctival nevi | | |
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Ho et al., 2007 | Ultrasound biomicroscopy for estimation of tumor thickness for conjunctival melanoma—retrospective review | 3 | UBM (50 MHz) | To assess the feasibility of using high frequency UBM in estimating thickness of conjunctival melanomas preoperatively | Conjunctival melanoma (3) | Patient 1: UBM thickness = 1.99 mm and Breslow thickness = 1.5 mm | |
Articles using AS-OCT in conjunctival and corneal tumors.
Author, year | Study | Number of patients | Imaging technique | Aim | Tumor type | Results | Conclusion |
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Shields et al., 2011 | Anterior segment optical coherence tomography of conjunctival nevus—retrospective interventional case series | 22 eyes of 21 patients | AS-OCT (1310 nm) | To evaluate conjunctival nevi using AS-OCT | Conjunctival nevi (22) | | |
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Welch et al., 2011 | Pterygia measurements are more accurate with anterior segment optical coherence tomography (a pilot study)—study design not given | 13 | AS-OCT (wavelength not mentioned) | To compare standard slit-lamp beam measurements of pterygia to computer caliper measurements of AS-OCT images | Pterygia | | |
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Shousha et al., 2011 | Diagnosis and management of conjunctival and corneal intraepithelial neoplasia using ultrahigh resolution optical coherence tomography—prospective, noncomparative, interventional case series | 7 | UHR-OCT (870 nm) | To report a novel diagnostic technique and a case series of CCIN diagnosed and followed up using prototype UHR-OCT | Conjunctival and corneal intraepithelial neoplasia (CCIN) | | |
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Kieval et al., 2012 | Ultrahigh resolution optical coherence tomography for differentiation of ocular surface squamous neoplasia (OSSN) and pterygia—prospective case series | 34 eyes of 34 patients | UHR-OCT (840 nm) | To assess the use of an UHR-OCT as an adjuvant diagnostic tool in distinguishing OSSN and pterygia | Conjunctival lesions (34) clinically suspicious for OSSN or pterygia | | |
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Shousha et al., 2013 | Diagnosis of ocular surface lesions using ultrahigh resolution optical coherence tomography—prospective, noncomparative, interventional case series | 54 | UHR-OCT (840 nm) | To assess the use of ultrahigh resolution (UHR) optical coherence tomography (OCT) in the diagnosis of ocular surface lesions | 24 conjunctival lesions, 19 corneoconjunctival lesions, 11 corneal lesions: primary acquired melanosis lesions (8/54), amelanotic melanoma lesions (5/54), nevi (2/54), ocular surface squamous neoplasia lesions (19/54), histiocytosis lesion (1/54), conjunctival lymphoma lesions (6/54), conjunctival amyloidosis lesions (2/54), pterygia lesions (11/54) | | |
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Nanji et al., 2015 | High resolution optical coherence tomography as an adjunctive tool in the diagnosis of corneal and conjunctival pathology—prospective case series | 82 | HR-OCT (830 nm) | To evaluate the use of a commercially available, high resolution, spectral-domain optical coherence tomography (HR-OCT) device in the diagnosis of corneal and conjunctival pathologies, with a focus on malignant lesions | Location of lesions not mentioned: Normal eyes (10), OSSN (21), pterygium or pingueculum (24), lymphoma (3), pigmented conjunctival lesions (nevus, flat melanosis, or melanoma) (18) and Salzmann nodular degeneration (6) | | |
Articles describing the use of UBM and AS-OCT in conjunctival and corneal tumors.
Author, year | Study | Number of patients | Imaging technique | Aim | Tumor type | Results | Conclusion |
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Buchwald et al., 2003 | Optical coherence tomography versus ultrasound biomicroscopy of conjunctival and eyelid lesions—prospective study | 38 tumors of 35 patients | UBM (30 MHz) and AS-OCT (1310 nm) | To compare the value of UBM and AS-OCT in the diagnosis of conjunctival and eyelid lesions | 13 conjunctival lesions and 25 eyelid lesions: | | |
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Bianciotto et al., 2011 | Assessment of anterior segment tumors with ultrasound biomicroscopy versus anterior segment optical coherence tomography in 200 cases—retrospective, noninterventional case series | 200 | UBM (50 MHz probe) and AS-OCT (1310 nm) | To compare UBM versus AS-OCT for imaging of tumors of the anterior segment of the eye | 6 conjunctival lesions (diagnosis not mentioned), 0 corneal lesions, 194 other locations: | | |
Lanzl et al. [
Buchwald et al. demonstrated in 28 patients with solid tumors of the conjunctiva that UBM can be an additional diagnostic tool, for example, to determine the margins of the solid tumors or cysts [
Similarly to the study of Buchwald et al., Lin et al. proved in 2 cases that UBM is a useful tool to show cysts in conjunctival lesions. This technique could be used for delineating the extent of the lesion before excision [
Ho et al. studied the assessment of tumor thickness in three conjunctival melanomas by means of UBM. They concluded that high frequency UBM is useful for estimating tumor thickness in conjunctival melanomas and can be used to determine the tumor depth prior to surgical resection [
The study of Shields et al. on 22 conjunctival nevi demonstrated that all margins of conjunctival nevi, including the deep borders, could be visualized by AS-OCT. AS-OCT images showed a high resolution in 100% of anterior borders and 82% of posterior borders [
Welch et al. studied the difference between the measurements of a pterygium by slit-lamp examination and by AS-OCT imaging [
Shousha et al. studied the use of UHR-OCT in the diagnosis and follow-up of conjunctival and corneal intraepithelial neoplasia (CCIN). UHR-OCT images of the 7 lesions discerned a thickened hyperreflective epithelium and abrupt transition from normal to hyperreflective epithelium. Their results demonstrated that macroscopically resolved residual tumor nodules can be visualized by UHR-OCT. They concluded that UHR-OCT is useful for guiding diagnosis and treatment follow-up of CCIN [
The results of the study of Kieval et al. showed that UHR-OCT of the anterior segment could be an accurate tool in differentiating ocular squamous cell carcinoma from pterygium [
In another study of Shousha et al., the use of UHR-OCT in the diagnosis of 54 ocular surface lesions was studied. It was demonstrated that when the clinical diagnosis of ocular surface lesions was uncertain, UHR-OCT images provided optical signs indicating more specific diagnosis and management. They concluded that this imaging technique can visualize the structure and location of the lesion and as such can aid in guiding the diagnosis and management [
Nanji et al. studied the use of high resolution, spectral-domain optical coherence tomography (HR-OCT) in the diagnosis of corneal and conjunctival pathologies, with a focus on malignant lesions. In this pilot study on 82 lesions, they concluded that HR-OCT was helpful to determine the etiology and to differentiate between multiple ocular surface lesions, including ocular surface squamous neoplasia, pterygium, nevi, and melanoma, as well as to evaluate resolution after treatment. However, this imaging technique was less useful in evaluating pigmented lesions. Even though this imaging technique cannot replace either clinical evaluation or histopathologic diagnosis, it can be an important aid in determining the diagnosis of ocular surface pathology and in determining disease resolution [
Buchwald et al. studied 13 conjunctival and 25 eyelid lesions. The authors concluded that, in solid tumors, the final diagnosis cannot be made based on UBM or AS-OCT alone [
Bianciotto et al. studied 200 eyes with anterior segment tumors. Even though they only included 6 conjunctival tumors, their study resulted in interesting conclusions. Comparison of UBM and AS-OCT showed that UBM had a better tumor visualization and better resolution of the posterior margin. UBM also had a better resolution for pigmented as well as for nonpigmented tumors. However, AS-OCT had better resolution of the anterior border and better resolution of the anterior segment anatomy. Posterior tumor shadowing was rarely found in UBM images and more common in AS-OCT. The image quality was good in UBM but less in AS-OCT. This study shows that AS-OCT is superior to UBM for the imaging of conjunctival lesions, because AS-OCT offers a higher resolution and conjunctival lesions are superficial and mostly not pigmented. Their findings demonstrate that AS-OCT is affected by optical shadowing in large pigmented lesions. AS-OCT uses light, which is more comfortable for the patient, but the light is blocked by opaque tissues which results in lower penetration depth. This is a crucial factor in the evaluation and treatment of anterior segment tumors. They conclude that AS-OCT is a useful tool in the evaluation of superficial nonpigmented lesions of the eye, although AS-OCT suffers from poor resolution and shadowing in large or pigmented lesions. In comparison, UBM can penetrate better through the lesion, which results in better visualization of the posterior tumor border and whole tumor configuration [
These studies showed that AS-OCT and UBM both have their advantages and disadvantages because of their specific characteristics. None can replace histopathological examination for diagnosis but they both give useful information helping in the differential diagnosis [
Although AS-OCT technically has a higher resolution than UBM [
For thicker lesions as a
Ho et al. investigated
Concerning
Shousha et al. found that UHR-OCT is a good technique when visualizing
UBM and AS-OCT both have a strong correlation with histopathology and they can both assess the structure and the extent of lesions in order to guide treatment [
A major limitation of most studies was the small study population, often leading to the conclusion that further research is needed. Furthermore, only a limited amount of tumor types was investigated, which makes it impossible to extrapolate these findings to all corneal and conjunctival tumors.
The literature shows that AS-OCT and UBM are both very useful and complementary techniques for the evaluation and follow-up of corneal and conjunctival tumors even though they cannot replace histopathological analysis for the diagnosis. Due to their different measuring technique, they have different advantages and disadvantages. The disadvantage of AS-OCT is that it cannot penetrate deeper than 1–3 mm and cannot penetrate through pigmented lesions. But for smaller lesions AS-OCT is a more accurate technique that can give detailed images of the remaining healthy cornea, can identify cysts, or might be useful in detecting tumor recurrence. For larger or pigmented lesions UBM can better delineate tumor margins and tumor thickness. More comparative studies are needed to investigate which imaging technique is most suitable for a certain tumor type.
The authors declare that there is no conflict of interests regarding the publication of this paper.
Katleen Janssens and Michelle Mertens contributed equally to this work.