Tarek Alasil

Evaluation of Optical Coherence Tomography Retinal Thickness Parameters for Use in Clinical Trials for Neovascular Age-Related Macular Degeneration

PURPOSE To investigate the relationship between automated and manually derived measurements of central retinal thickness from optical coherence tomography (OCT) and to determine the relationship between the foveal center point (FCP) and the foveal central subfield (FCS) in neovascular age-related macular degeneration (AMD). METHODS Data were collected from 216 patients with newly diagnosed neovascular AMD, who underwent StratusOCT imaging at diagnosis. Raw StratusOCT images for each patient were analyzed with the publicly available custom software OCTOR, which allows accurate manual grading of OCT B-scans. Manually derived central retinal thickness measurements were compared with measurements obtained from automated StratusOCT analysis. Manually obtained measurements of FCP and FCS were also compared. RESULTS The mean (+/-SD) difference in thickness between automated and manually derived FCP thickness was 7.9 microm (+/-90.8), but the maximum difference was 455 microm. The limits of agreement (95% confidence interval), between automated and manually obtained FCP thicknesses, were -173.7 microm (lower limit) and 189.6 microm (upper limit), with a coefficient of determination (R(2)) of 0.49 (P < 0.001). In contrast, the R(2) for manually derived FCP and manually derived FCS thickness was 0.94 (P < 0.001), with a smaller mean (+/-SD) difference in thickness of 13.8 microm (+/-29.8). CONCLUSIONS Manual correction of errors in automated OCT segmentation may be necessary for accurate interpretation of anatomic outcomes for clinical trials of neovascular AMD. In addition, although measurement of FCS remains preferable for assessment of central retinal thickness, accurate measurement of FCP may represent an adequate alternative when FCS is unavailable.

EN FACE IMAGING OF THE CHOROID IN POLYPOIDAL CHOROIDAL VASCULOPATHY USING SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY

OBJECTIVE To define morphologic features of polypoidal choroidal vasculopathy (PCV) using en face images from swept-source optical coherence tomography (SS OCT). DESIGN Prospective cross-sectional study. METHODS The study included 10 eyes from 6 patients with PCV and 10 eyes from 5 age-matched normal subjects. All subjects were prospectively scanned with a prototype SS OCT system. A motion correction algorithm was applied to correct and merge scans into a single volumetric dataset. En face images were generated at intervals of 4.13 μm (1 pixel) relative to the Bruch membrane. RESULTS Age ± standard deviation for the normal group was 62.4 (±12.1) years and for the PCV group was 68.3 (±5.2) years. En face SS OCT imaging of PCV eyes demonstrated the relationship between larger pigment epithelial detachments (PEDs) and small adjoining PEDs that correlated with the polypoidal lesions seen on indocyanine green angiography in all PCV eyes. En face SS OCT demonstrated choroidal vascular abnormalities in 7 out of 7 eyes with PCV, and in 2 out of 3 enrolled fellow eyes in patients with unilateral PCV. Out of 7 PCV eyes, focal choroidal vascular dilation was noted in 3 eyes and diffuse choroidal vascular dilation was noted in 1 eye. In addition, a branching vascular network was noted above the Bruch membrane in 1 eye, below the Bruch membrane within the choriocapillaris in 1 eye, and in the larger choroidal vascular layer in 1 eye. CONCLUSIONS En face SS OCT provides an in vivo tool to visualize the pathologic features and the choroidal vasculature in PCV.

Characterization of Choroidal Layers in Normal Aging Eyes Using Enface Swept-Source Optical Coherence Tomography

Purpose To characterize qualitative and quantitative features of the choroid in normal eyes using enface swept-source optical coherence tomography (SS-OCT). Methods Fifty-two eyes of 26 consecutive normal subjects were prospectively recruited to obtain multiple three-dimensional 12x12mm volumetric scans using a long-wavelength high-speed SS-OCT prototype. A motion-correction algorithm merged multiple SS-OCT volumes to improve signal. Retinal pigment epithelium (RPE) was segmented as the reference and enface images were extracted at varying depths every 4.13μm intervals. Systematic analysis of the choroid at different depths was performed to qualitatively assess the morphology of the choroid and quantify the absolute thicknesses as well as the relative thicknesses of the choroidal vascular layers including the choroidal microvasculature (choriocapillaris, terminal arterioles and venules; CC) and choroidal vessels (CV) with respect to the subfoveal total choroidal thickness (TC). Subjects were divided into two age groups: younger (<40 years) and older (≥40 years). Results Mean age of subjects was 41.92 (24-66) years. Enface images at the level of the RPE, CC, CV, and choroidal-scleral interface were used to assess specific qualitative features. In the younger age group, the mean absolute thicknesses were: TC 379.4μm (SD±75.7μm), CC 81.3μm (SD±21.2μm) and CV 298.1μm (SD±63.7μm). In the older group, the mean absolute thicknesses were: TC 305.0μm (SD±50.9μm), CC 56.4μm (SD±12.1μm) and CV 248.6μm (SD±49.7μm). In the younger group, the relative thicknesses of the individual choroidal layers were: CC 21.5% (SD±4.0%) and CV 78.4% (SD±4.0%). In the older group, the relative thicknesses were: CC 18.9% (SD±4.5%) and CV 81.1% (SD±4.5%). The absolute thicknesses were smaller in the older age group for all choroidal layers (TC p=0.006, CC p=0.0003, CV p=0.03) while the relative thickness was smaller only for the CC (p=0.04). Conclusions Enface SS-OCT at 1050nm enables a precise qualitative and quantitative characterization of the individual choroidal layers in normal eyes. Only the CC is relatively thinner in the older eyes. In-vivo evaluation of the choroid at variable depths may be potentially valuable in understanding the natural history of age-related posterior segment disease.

Pan retinal photocoagulation for proliferative diabetic retinopathy: pattern scan laser versus argon laser.

Purpose of review Diabetic retinopathy is the leading cause of visual impairment in working-age adults worldwide. Pan retinal photocoagulation (PRP) has provided an effective treatment to decrease the risk of severe vision loss in patients with proliferative diabetic retinopathy for the past four decades. Pattern scan laser (PASCAL) was developed to minimize the side effects of PRP. The purpose of this review is to discuss the differences between the traditional argon laser and the PASCAL. Recent findings PASCAL can achieve comparable results with the conventional argon PRP in the treatment of patients with diabetic retinopathy. The PASCAL delivery system creates well aligned arrays of retinal lesions in a shorter period. PASCAL provides amore comfortable profile when compared to the argon laser. Summary The PASCAL is now being substituted for the conventional argon laser for PRP in many clinics. Ophthalmologists should keep in mind that adjusting the PASCAL settings (including the duration, number, and size of laser burns) might become necessary to maintain regression and eliminate recurrence of neovascularization in patients with proliferative diabetic retinopathy. Further studies are needed to determine the parameters for optimal safety and efficacy on the PASCAL.

Optical Coherence Tomography in Pediatric Ophthalmology: Current Roles and Future Directions

The application of existing optical coherence tomography (OCT) technology to the pediatric population is limited in both the design specification of the device and its hardware. However, the potential of OCT in the pediatric population has not been fully realized. The authors review the literature, highlighting the currently available spectral-domain OCT technology and summarizing the reported normal pediatric OCT parameters for retinal nerve fiber layer and macular thickness. They also review the pediatric ophthalmological conditions in which OCT has been used and discuss advancements in OCT design and their potential applications to the pediatric population. The use of OCT in pediatric populations is likely to increase greatly in the coming years, aiding clinical decision-making and providing new insights into pediatric disease pathophysiology.

Purtscher-Like Retinopathy: Optical Coherence Tomography and Visual Field Findings.

A 30-year-old male presented with decreased vision in the right eye after a recent hospitalization for acute pancreatitis. On presentation, his visual acuity was 20/100 right eye (OD) and 20/20 left eye (OS). The funduscopic examination findings were consistent with Purtscher-like retinopathy (PLR). Cirrus HD-OCT (Spectral Domain Technology, Zeiss) of the right eye showed retinal nerve fiber layer swelling and significant subretinal fluid. Humphrey visual field (Central 24-2) revealed generalized defect on the right and inferior nasal step on the left. During the next 6 months, the patient had improvement in visual acuity (20/30 OD and 20/20 OS) and normalization of optical coherence tomography (OCT) findings. However, the visual field (VF) worsened bilaterally suggesting that the injuries induced by micro-infarctions at the level of the retinal nerve fiber layer (RNFL) were not reversible. To our knowledge, there have been no reports in the literature that compare high-resolution OCT and VF findings in patients with PLR.

Central retinal vein occlusion: a case report and review of the literature

IntroductionCentral retinal vein occlusion is one of the major causes of severe vision impairment and blindness in adults.Case presentationWe present a case of unilateral ischemic central retinal vein occlusion in a 54-year-old woman with history of uncontrolled hypertension and open angle glaucoma. Laboratory tests including complete hypercoagulability and thrombotic workup were completed.ConclusionOur case illustrates an interesting presentation of unilateral ischemic central retinal vein occlusion, where hypertension and glaucoma were thought to be the main risk factors. Close follow up, tight blood pressure and glaucoma control are crucial to prevent similar scenario in the fellow eye.

Spectral-domain and swept-source OCT imaging of asteroid hyalosis: a case report.

A 72-year-old man with diabetes was referred to the retina clinic for diabetic retinopathy. Detailed funduscopic examination of the left eye was limited by prominent asteroid hyalosis. Spectral-domain (SD) and swept-source (SS) optical coherence tomography (OCT) were utilized to examine the vitreous, vitreoretinal interface, and the morphology of the retina. Asteroid hyalosis induced artifacts of the OCT images, which resolved when the appropriate imaging protocols were applied. SS-OCT may show superior diagnostic and preoperative capabilities when compared to SD-OCT in the settings of asteroid hyalosis-induced media opacity.

BILATERAL DIFFUSE UVEAL MELANOCYTIC PROLIFERATION: A CASE REPORT.

Purpose: To report a case of bilateral diffuse uveal melanocytic proliferation (BDUMP) in the setting of metastatic ovarian cancer. Methods: In this observational case report, a 59-year-old woman presented with bilateral worsening vision and photophobia. She had been diagnosed with metastatic ovarian cancer 5 years prior for which she received Tamoxifen. Ophthalmic examination was completed followed by fluorescein angiography and optical coherence tomography (Spectralis OCT; Heidelberg Engineering). Results: The visual acuity was 20/150 in both eyes. Exam demonstrated an iris pigmented lesion in the right eye, bilateral nuclear sclerotic cataracts, multiple orange lesions in the fundus, elevated pigmented uveal melanocytic tumors with diffuse choroidal thickening and multifocal early hyperfluorescence of these lesions (giraffe-like pattern) on fluorescein angiography, and exudative retinal detachment on OCT. The patient was diagnosed with BDUMP in the setting of metastatic ovarian carcinoma. Further metastatic workup demonstrated enlarged lymphadenopathy in the right axilla and inguinal regions. The patient declined chemotherapy and was initiated on plasmapheresis. Conclusions: BDUMP is a peculiar paraneoplastic syndrome in the setting of metastatic ovarian cancer, where antigens from the retinal pigment epithelium, iris and choroidal melanocytes cross-react with ovarian tumor cell antibodies that are circulating in the serum. Plasmapheresis can decrease the concentrations of the antibodies, maintain reasonable functional vision and improve the quality of life.

Idiopathic retinal vasculitis, aneurysms and neuroretinitis case report

Purpose To report a case of idiopathic retinal vasculitis, aneurysms and neuroretinitis (IRVAN) in a young woman. Observations A 21-year-old white female patient was referred to retina clinic with decreased vision in the left eye. On examination, best corrected visual acuity was 20/20 in the right eye and counting fingers in the left eye. Fundus examination revealed bilateral optic disc edema, peripapillary and macular exudates, retinal arterial aneurysms, and venous beading. In the left eye, there was a large focus of exudative material in the central macula. Examination of the peripheral retina was unremarkable, bilaterally. Fluorescein angiography demonstrated arterial aneurysms and venous beading in both eyes, with optic nerve activity and vascular sheathing noted on late frames in both eyes. In the left eye, there was a large central area of blockage corresponding to hard exudates surrounding a more central area of hyperfluorescence with leakage, representing retinal neovascularization. Review of systems and extensive laboratory workup were negative. The patient was diagnosed with IRVAN. She was observed, and her exam at 6-month follow-up revealed low grade inflammation for which the patient was started on oral prednisone. Conclusions and Importance Management of IRVAN remains challenging because of its idiopathic nature and the lack of controlled clinical trials for such a rare entity. Bilateral involvement in IRVAN is variable and close follow up is crucial.