Ahmad A. Alwassia

Retinal Neovascularization Secondary to Proliferative Diabetic Retinopathy Characterized by Spectral Domain Optical Coherence Tomography

Purpose: The purpose of this study was to characterize diabetic retinal neovascularization (NV) and accompanying retinal and vitreal morphologic changes using high-resolution spectral domain optical coherence tomography. Methods: A cross-sectional retrospective analysis was performed on 16 eyes of 14 nonconsecutive subjects with proliferative diabetic retinopathy that were seen between August 2011 and December 2011 at the New England Eye Center, Boston, MA. Patients who had NV of the disk, NV elsewhere, and intraretinal microvascular abnormalities were scanned using optical coherence tomography directly over the region of the abnormal vessels. Results: Characteristic changes of the retinal vasculature, retina, and vitreous were seen in the 16 eyes with NV. This study describes optical coherence tomography characteristics of 1) NV of the disk, 2) NV elsewhere, 3) intraretinal microvascular abnormality, 4) NV causing traction without retinal detachment; and 5) NV causing traction with retinal detachment. The morphologic appearance of vitreous traction was found to be consistent with the previous histologic reports. Conclusion: It is possible to image diabetic NV using spectral domain optical coherence tomography and to visualize the spectrum of retinal, retinal vascular, and vitreal changes seen through these areas of abnormal retinal vasculature.

Analysis of the Morphology and Vascular Layers of the Choroid in Retinitis Pigmentosa Using Spectral-Domain OCT

BACKGROUND AND OBJECTIVE To analyze choroidal morphology and vascular layers in eyes with retinitis pigmentosa (RP) using spectral-domain optical coherence tomography. PATIENTS AND METHODS Cross-sectional, retrospective analysis of 14 patients (14 eyes) with RP and 33 healthy subjects (33 eyes) who underwent high-definition one-line raster scanning at a single center. Two independent raters evaluated the morphology, thickness, and vascular layers of the choroid in both groups. RESULTS The choroid had an irregular shape in 11 of 14 eyes (79%) with RP. The thickest point of choroid was not subfoveal as in healthy eyes, and exaggerated nasal thinning of the choroid was observed in nine of 14 eyes (65%) with RP. Mean subfoveal total choroidal thickness and large choroidal vessel layer thickness were significantly lower in eyes with RP (P = .04 and P = .02, respectively) than in healthy eyes. CONCLUSION Choroidal morphology is altered and an exaggerated thinning of the large choroidal vessel layer is observed in eyes with RP. Further studies involving correlation of disease stage and severity with choroidal changes may provide further insight into the involvement of choroid in RP and other inherited retinal dystrophies.

Analysis of choroidal thickness in eyes treated with focal laser photocoagulation using SD-OCT

OBJECTIVE To analyze the effect of focal laser photocoagulation on choroidal thickness in patients with diabetic macular edema (DME), using spectral-domain optical coherence tomography (SD-OCT). DESIGN Retrospective review. PARTICIPANTS Twenty-two eyes of 22 patients diagnosed with DME and treated with focal laser photocoagulation (treatment group) and 19 fellow treatment-naive eyes (control group) who underwent high-definition 1-line raster scanning using the Cirrus SD-OCT at the New England Eye Center, Tufts Medical Center (Boston, Mass.) between November 2009 and April 2012. METHODS The SD-OCT images were analyzed for the measurement of choroidal thickness by 2 independent observers experienced in analyzing OCT images, before treatment and at 3 months after focal laser photocoagulation in the treatment group, and at baseline (when the fellow eye in the treatment group was treated) and at 3-month follow-up in the control group. RESULTS There was no significant difference in the mean choroidal thickness in the treatment and control groups (n = 22, p = 0.93 and n = 19, p = 0.1, respectively) at 3-month follow-up. There was no significant association of the number of focal laser treatments with the mean choroidal thickness (n = 41, r = -0.31, p = 0.68). CONCLUSIONS Focal laser photocoagulation does not appear to alter choroidal thickness in eyes with DME in the short term, as assessed using SD-OCT. Long-term follow-up of eyes with DME and other retinal diseases treated with laser photocoagulation may provide further insight into the effects of this treatment modality on the choroid.

Use of Optical Coherence Tomography in the Diagnosis and Management of Uveitis

Uveitis is a challenging disease. It represents a major cause of ocular morbidity worldwide. More than half of all patients with uveitis develop sight threatening complications related to their disease, and up to 35% of patients suffer severe visual impairment 1, 2. Uveitis and its complications are responsible for 5% to 10% of all causes of legal blindness in developed countries 1, 3. The causes of uveitis are numerous, and include infectious conditions, autoimmune diseases, trauma and tumors (masquerade syndrome). To develop an accurate differential diagnosis, clinicians must consider all available information, including the patient history, anatomic location of the inflammation (anterior or posterior), character (granulomatous vs. non granulomatous), laterality, and chronicity of inflammation. Moreover, diagnostic tools, such as fluorescein angiography (FA), indocyanine green angiography (ICG), optical coherence tomography (OCT) and ultrasound, play an important role in the diagnosis and in the management of the uveitis 4. Until recently, fluorescein FA was the primary imaging modality used to detect macular edema and other features related with uveitis like choroidal neovascularization and serous retinal detachment. Although FA is useful for determining the presence of vascular leakage, this technique does not provide any three-dimensional anatomic information about the retinal layers, the retinal pigment epithelium (RPE) or the choroid. The development of OCT makes it possible to have high-resolution cross-sectional images of the retina or optic nerve. OCT is now proven to be an effective noninvasive method in detecting pathologic features in uveitis and is rapidly gaining popularity as an ancillary exam. It may be used to assist in the diagnosis of uveitis and may be repeated safely during follow-up to monitor response to any intervention 5, 6. Recently, the introduction of spectral domain OCT (SDOCT) has improved image quality. Spectral domain, a type of fourier domain detection, uses a high-speed spectrometer to measure light echoes from all time delays simultaneously enhancing OCT capabilities. The reference mirror does not require mechanical scanning. Improved sensitivity enables dramatic improvements in sampling speed and signal-to-noise ratio 7, 8. SD detection, coupled with improvements in light sources, achieves axial scanning speeds of greater than 20,000 A-scans per second with an axial resolution of 3 μm to 7 μm in the eye. Consequently SDOCT has the advantage of detecting small changes in the morphology of the retinal layers and subretinal space, allowing for precise anatomic detection of microstructural changes that may corresponds to progression or regression of chorioretinal lesions or complications secondary to uveitis6. In addition, SDOCT is also used for anterior segment imaging where it may illustrate features of anterior uveitis and its complications. This review focuses on SDOCT imaging in uveitis. It will first review OCT imaging in anterior uveitis; then, it will describe the image features observed in the posterior uveitis. OCT and Anterior Uveitis Anterior segment optical coherence tomography (ASOCT) allows the visualization of various features of the anterior segment, including iris thickness, anterior chamber (AC) depth, the extent of anterior synechiae, iris bowing, and angle lesions. In vivo cross-sectional imaging of the anterior segment from ASOCT is particularly useful in the presence of corneal opacity and ocular inflammation, where it is often difficult to use slit-lamp biomicroscopy to visualize the anterior segment. It can serve as an non-invasive method for assessment of anterior uveitis and its complications 9, and can detect features of uveitis such as inflammatory cells, keratic precipitates (Figure 1A), fibrin (Figure 1B), and corneal edema (Figure 1C). In addition, positive posterior segment findings on OCT (e.g. increased macular thickness, retinal edema) can often reinforce anterior uveitis findings and may suggest its manifestation as part of a panuveitis associated with systemic illnesses such as sarcoidosis and Vogt-Koyanagi-Harada syndrome 9, 10. Figure 1 Representative ASOCT images show different features of anterior uveitis (A) Keratic precipitates (arrow) on ASOCT; (B) Fibrin deposition (arrow); (C) Corneal edema (arrow); (D) Inflammatory cells in the anterior chamber, visualized as hyperreflective ... Anterior Chamber Inflammatory Cells on ASOCT Lowder et al. 11 used a high-speed prototype SDOCT (2,000 A-scan/sec, 1.3 micron wavelength) to characterize inflammatory and pigmented cells in the anterior chamber (AC) as hyperreflective spots. In 28 non-granulomatous anterior uveitic eyes, a significant correlation was found between the cell count on OCT and the clinical grading from slit-lamp biomicroscopy. Similarly, a significant correlation was found between 6 eyes with pigmentary particles on OCT and clinical grading. Another study by Agarwal et al 12, inflammatory cells in the AC were visualized on ASOCT as hyperreflective spots (Figure 1D) in eyes compromised AC visualization secondary to corneal edema or opacity. In their study of 62 eyes with AC inflammation, 91.6% of eyes with corneal edema (n=12) had identifiable hyperreflective spots consistent with AC cells on ASOCT, which were manually counted and graded using the standardization of uveitis nomenclature (SUN) criteria. At the same time, keratic precipitates (Figure 1A) were seen in 12 eyes as discrete hyperreflective spots attached to the cornea endothelium, and fibrinous membrane (Figure 1B) were detected in 4 eyes in the papillary area or endothelium of the cornea.

Sequential optical coherence tomography images of retinal necrosis in acute ocular toxoplasmosis.

PURPOSE To describe the features of sequential spectral-domain optical coherence tomography (OCT) images in an eye with acute primary toxoplasmosis. METHODS Case report of an individual diagnosed with acute primary toxoplasmic retinochoroiditis. Initial and follow-up spectral-domain OCT findings are described. RESULTS This patient developed retinitis as a result of an acute infection consistent with Toxoplasma gondii suggested by toxoplasma-specific IgM serology and the response to therapy. The retinitis appeared initially as a hyperreflective region on spectral-domain OCT. An intraretinal cyst consistent with T. gondii parasitic infection was identified. Subsequent OCT images demonstrated progression to full-thickness retinal necrosis with the development of cystic spaces in the retina. CONCLUSION Optical coherence tomography may be useful in characterizing the features, extent, and location of retinitis caused by T. gondii. Specific OCT features may indicate whether the infection is acute phase or becoming quiescent.

De Novo Appearance of a Choroidal Osteoma in an Eye With Previous Branch Retinal Vein Occlusion

This report describes the de novo appearance of a choroidal osteoma occurring 8 years after laser photocoagulation for previous branch retinal vein occlusion (BRVO). A 62-year-old man presented with an asymptomatic yellowish orange lesion in the macula on fundus examination of his left eye during a regular follow-up visit for bilateral BRVO associated with macular edema that had previously been treated with laser photocoagulation. The lesion was observed for 1.5 years until a decrease in vision occurred. Fundus photography revealed a yellow-to-orange, well-defined lesion in the macular region. Fluorescein angiography was consistent with choroidal neovascularization (CNV). Optical coherence tomography and B-scan ultrasonography showed features consistent with choroidal osteoma. This is the first report of the de novo appearance of a choroidal osteoma occurring years after laser photocoagulation for BRVO. CNV developed secondary to the lesion, which was treated with intravitreal bevacizumab, leading to subjective and anatomic improvement.