Journal of Ophthalmology

Journal of Ophthalmology / 2012 / Article
Special Issue

Imaging the Anterior Segment: High-Frequency Ultrasound and Anterior Segment OCT

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Clinical Study | Open Access

Volume 2012 |Article ID 313120 | 6 pages | https://doi.org/10.1155/2012/313120

Application of Anterior Segment Optical Coherence Tomography in Pediatric Ophthalmology

Academic Editor: Charles J. Pavlin
Received27 Nov 2011
Accepted16 May 2012
Published09 Aug 2012

Abstract

Purpose. Application of anterior segment optical coherence (AS-OCT) in pediatric ophthalmology. Methods. Retrospective clinical study case series of 26 eyes of 19 pediatric patients throughout a 21-month period, presenting anterior segment pathologies, were submitted to AS-OCT examination (OCT Visante, 1310 nm, Zeiss), noncontact technique, no sedation requirement. Results. AS-OCT images were obtained from 19 patients (range: 2 months to 12 years). Clinical diagnosis of anterior segment abnormalities included cornea disease ( 𝑛 = 7 ), congenital anterior segment conditions ( 𝑛 = 1 0 ), ocular trauma ( 𝑛 = 1 ), anterior segment surgeries ( 𝑛 = 2 ), iridocorneal angle abnormalities ( 𝑛 = 4 ), intermediate uveitis ( 𝑛 = 2 ). The most common OCT findings were corneal hyperreflectivity and thickening ( 𝑛 = 1 5 ), shallow anterior chamber with iris-lens diaphragm anterior displacement ( 𝑛 = 4 ), atypical corneal curvature ( 𝑛 = 4 ), corneal thinning ( 𝑛 = 4 ), peripheral synechiae with angle closure ( 𝑛 = 3 ), increased anterior chamber depth ( 𝑛 = 2 ), and proximal portion of glaucoma drainage tube ( 𝑛 = 2 ). Conclusion. In the present study, noncontact AS-OCT demonstrated to be a feasible technique to evaluate the anterior segment providing anatomic details and useful to clarify diagnosis in the pediatric population.

1. Introduction

Optical coherence tomography (OCT) is a high-resolution imaging technique, which allows a noninvasive tissue observation through sectional cuts of the ocular structure. This concept is based on the measurement of low-coherence delay infrared light reflected onto a tissue to be examined with the use of interferometry [1, 2]. The system with a wavelength of 1310 nm has allowed greater penetration into opaque tissues such as sclera and limbus for the visualization of angular structures [14]. Anterior segment OCT (AS-OCT) technology has improved in the last years with the development of higher resolution systems, considering time domain and Fourier-domain systems.

In most cases, OCT has its usage limited to the adult population. The role of anterior segment OCT in ocular pediatric diseases has not been well reported [5]. Anterior segment anatomy evaluation in children is challenging and was restricted to high-frequency ultrasound techniques (UBM), which required immersion technique and sedation [6].

2. Patients and Methods

Retrospective analysis of patients under 12 years of age presenting with anterior segment conditions and requiring imaging techniques for elucidation were submitted to anterior segment OCT examination (Visante OCT, 1310 nm, Carl Zeiss Meditec Inc., Dublin, USA), during a 21-month period (January 2008 to September 2009): protocol approved by the UNIFESP Ethics Committee in Research under the number CEP/UNIFESP no. 0788/09.

Presumed ocular diagnosis was considered in comparison to AS-OCT findings.

For AS-OCT examination no sedation was necessary; anesthetic eye drops or eyelid speculum was not routinely used, except for one only eye of a 2-month-old patient who required the use of topical hydrochloride proxymetacaine 0.1% (Alcon). All images were acquired in standard light conditions using the anterior segment single, dual, and/or quad scan (scan width: 16 mm; scan depth: 8 mm) and cornea single and enhanced cornea protocols (scan width: 10 mm; scan depth: 4 mm) by two examiners (PHS, NA), adding the pachymetric map, when needed. Poor vision, lack in fixation or nystagmus usually determine poor perpendicularity. Images were scanned at the horizontal meridian (0° and 180°) and, when possible, also at the vertical meridian (90° and 270°) and the oblique meridians (135° and 315°, 45° and 225°).

The cross-sectional AS-OCT images with the best quality were further analyzed using software provided by the manufacturer. This included the measurement of the following parameters: cornea thickness, anterior chamber depth (ACD), internal AC diameter, evaluation of the anterior chamber angle (ACA). Qualitative analysis was used to evaluate corneal and lens reflectivity, to describe synechiae and malformations, and to analyze internal structure of superficial lesions.

3. Results

The sample included 19 patients, their age ranging from 2 months to 12 years old.

Anterior segment OCT exam was performed in 26 eyes with presumed diagnosis of anterior segment.

Demographic data and presumed diagnosis were listed in Table 1. AS-OCT findings related to diseases of the anterior segment were grouped in Table 2.


Patient no.GenderAge (years)Eye Presumed clinical diagnosis

1M6OUMucopolysaccharidosis type IV
2M11OSKeratoconus
3F11OUMucopolysaccharidosis type IV
4M2ODDermoid cyst
5F12OSPerforating corneal trauma
6M0.17 (2 mo)OSMesoectodermal dysgenesis
7F6OSMesoectodermal dysgenesis
8M7OUMicrophthalmia
9F11ODCornea transplant and glaucoma drainage tube
10F5OSSclerocornea
11F10ODUveitis, peripheral anterior synechia and cataract
12M7OUCongenital glaucoma
13F11OUIntermediate uveitis
14F11OUNeovascular glaucoma
15M12OUKeratoglobus OD, keratoconus OS
16F12ODGlaucoma drainage tube
17M11OSCiliary body lesion with anterior peripheral synechiae
18F5OUCongenital cataract, microphthalmia and iris coloboma
19M11ODKeratoconus and hydrops

Legend: M: male; F: female; OU: both eyes; OD: right eye; OS: left eye.

Anterior segment pathologyNumber of eyes

Cornea diseases
 Mucopolysaccharidosis4
 Keratoconus3
Anterior segment congenital condition
 Mesoectodermal dysgenesis2
 Sclerocornea1
 Congenital glaucoma2
 Microphthalmia3
 Keratoglobus1
Ocular trauma
 Self-sealing corneal penetrating injury1
Anterior segment surgery
 Cornea transplant and glaucoma drainage tube1
 Glaucoma drainage tube1
Iridocorneal angle abnormalities
 Anterior synechiae post-uveitis1
 Neovascular glaucoma2
 Synechia associated to ciliary body lesion1
Intermediate Uveitis2
Ocular surface lesions
 Corneoscleral dermoid1

Congenital anterior segment changes were the most frequent indications including mucopolysaccharidosis ( 𝑛 = 4 ), keratoconus ( 𝑛 = 3 ), and microphthalmia ( 𝑛 = 3 ).

Corneal changes such as increased reflectivity ( 𝑛 = 9 ) and thickening ( 𝑛 = 6 ) were the most observed tomographic findings, as referred to in Table 3.


Anatomic landmarkAS-OCT findingNumber of eyes

CorneaIncreased stromal reflectivity9
Thinning3
Thickening6
Stromal heterogeneity and irregular thickness1
Increased anterior curvature3
Increased posterior curvature1
Host-donor junction in corneal transplantation1

Anterior chamberDecreased anterior chamber depth4
Increased anterior chamber depth2
Position of glaucoma drainage tube2

Crystalline lensCongenital cataract2

IrisPeripheral synechiae3

ScleraCorneoscleral dermoid1

3.1. Application of AS-OCT in Cornea-Related Diseases

Preoperative evaluation of corneal opacities, providing accurate measurement of the scar depth (range: 344 to 399 microns) and of the residual stroma thickness, 𝑛 = 1 5 eyes; and postoperative evaluation of corneal penetrating transplant (donor recipient wound evaluation and pachymetric map, 𝑛 = 1 ) and glaucoma drainage tube positioning in relation to the peripheral cornea ( 𝑛 = 2 ) as in Figures 1(a) and 3(b). In case of graft failure an overall thickening of the cornea would be detected (Figure 3(a)). One case (Case 8, Table 3) presented a self-sealing perforating corneal injury and was handled with bandage contact lens and local adhesive application; AS-OCT allowed to evaluate the underlying residual stroma thickness (220 microns, Figure 1(b)). In one eye of an 11-year-old child with keratoconus, AS-OCT provided the pachymetric map objectively measuring and localizing corneal thinning (352 microns, Figure 1(c)).

3.2. Application of AS-OCT in Developmental Anomalies of the Anterior Segment

Mesoectodermal dysgenesis (as Peters syndrome, 2 eyes) demonstrated increased reflectivity of the central cornea (leukoma) associated with local indentation (malformation) of the posterior surface (Descemet’s membrane defect, Figure 2(a)), with overall increased stromal reflectivity and thickness (Figure 2(b)). Findings of decreased anterior chamber depth and peripheral synechiae were associated ( 𝑛 = 2 eyes).

3.3. Applications of AS-OCT in Microphthalmia

Reduced anterior chamber depth ( 𝑛 = 1 eyes, ACD = 1.32 mm) and inner AC diameter (9.47 mm). Both eyes were also submitted to high frequency ultrasound with a 50 MHz transducer, and measurements were comparable (Figures 2(c) and 2(d)).

3.4. Application of AS-OCT in Evaluating the AC Angle

Two eyes with neovascular glaucoma and vitreous hemorrhage presented generalized angle closure. UBM was performed after glaucoma drainage implantation (Figures 4(a) and 4(b)). Congenital glaucoma ( 𝑛 = 2 eyes) presented wide angle, increased AC depth (3.75 mm), and inner AC diameter (13.66 mm), as in Figure 4(c).

3.5. Application of AS-OCT in Anterior Segment Tumors

Limbal dermoid cyst ( 𝑛 = 1 eye) presented as an elevated highly reflective lesion at the limbal region, that apparently occupied deep corneal stroma. Lateral boundaries were determined (radial measurement = 5.52 mm, Figure 4(d)), but due to local shadowing artifact, the posterior limit was uncertain.

4. Discussion

Anterior segment OCT is an ancillary exam suitable for glaucoma evaluation [1, 4], allows the measurement of the anterior chamber inner diameter [1, 3], and provides a pachymetric map [7], also suitable for evaluation of ectatic disorders [1], corneoscleral abnormalities [1], corneal transplant followup [1], and anterior segment tumors [1].

There are limitations in the evaluation through AS-OCT considering the lack of information of the posterior chamber, such as the ciliary body and sulcus. High-frequency ultrasound methods (35 to 50 MHz) usually allow better penetration into opaque and high-density structures [3], requiring an immersion technique and contact to the globe.

The usage of AS-OCT has been limited to the adult population [2, 4, 7]. The application of this method in the evaluation of pediatric ocular diseases has not been well defined [5].

In the pediatric population, reports using a posterior segment OCT system (820 nm) demonstrated mean values to the foveal thickness (186 microns) and nervous fiber layer thickness (108.27 microns), additionally allowing an analysis of the optical disc [8, 9] and a detailed morphological description of the macula in premature children [10]. The observation of prevalent intraocular tumors and simulatory lesions in children was also validated with posterior segment OCT method [5, 11]. Handheld posterior segment OCT devices are available to help surgeons at exams under anesthesia in the pediatric population.

Some eyes in the sample were evaluated with AS-OCT and comparatively with high frequency ultrasound (UBM) and similarities were reported.

Anterior segment OCT may be performed without difficulties in many children and its application will certainly expand relating to its non-contact and noninvasive scanning method. However, in some cases of non-cooperative children and children who present low visual acuity, condition which in other methods may not be relevant, the examination under anesthesia is recommended if a handheld AS-OCT device would be available [12, 13].

In the present study, AS-OCT was validated as a non-contact imaging method to evaluate the anterior segment of the pediatric population. In children, AS-OCT acquisition is considered more difficult because of the lack of cooperation in fixating. A concern was also the presence of dense corneal opacities, which could impede optimal imaging of the anterior segment structures. Both concerns did not prevent the acquisition of good quality AS-OCT images.

AS-OCT can be considered as a feasible imaging technique to be used with children and useful to clarify diagnosis and for clinical and/or surgical follow-up of anterior segment disorders. The development of handheld devices for anterior segment OCT evaluation is expected to improve the standard of medical care.

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Copyright © 2012 Ricardo Salles Cauduro et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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