Publications by authors named "Grant D Aaker"

10 Publications

  • Page 1 of 1

Three-dimensional spectral domain optical coherence tomography and light microscopy of an intravitreal parasite.

J Ophthalmic Inflamm Infect 2015 Dec 19;5(1):33. Epub 2015 Nov 19.

Department of Ophthalmology, Weill Cornell Medical College, New York, NY, USA.

Background: Various imaging modalities play a role in diagnosing parasitic infections of the eye. We describe the spectral domain optical coherence tomography (SD-OCT) findings of an intravitreal parasite with subsequent evaluation by light microscopy.

Findings: This is a case report of a 37-year-old Ecuadorian man who presented with uveitic glaucoma and a new floater in his left eye for 1 week's duration. Full ophthalmic examination revealed an intravitreal parasite. Color fundus photography, fluorescein angiography (FA), ocular ultrasonography (US), and SD-OCT were performed. The parasite was removed via 23-gauge pars plana vitrectomy and sent to pathology for evaluation. Color fundus photography and ocular ultrasonography demonstrated an elongated foreign body within the vitreous above the retina. FA demonstrated minimal vascular changes in the vicinity of the parasite. SD-OCT was utilized to visualize the parasite and to create a three-dimensional (3D) image. The parasite was determined to be most consistent with Gnathostoma spp. by morphologic analysis.

Conclusions: This is the first reported case of SD-OCT of an intravitreal parasite with corresponding evaluation by pathology. SD-OCT allows non-invasive, high-resolution visualization and 3D reconstruction of parasitic anatomy which may help establish tomographic criteria for species identification.
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http://dx.doi.org/10.1186/s12348-015-0064-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4653122PMC
December 2015

Peripheral retinal ischaemia, as evaluated by ultra-widefield fluorescein angiography, is associated with diabetic macular oedema.

Br J Ophthalmol 2012 May 15;96(5):694-8. Epub 2012 Mar 15.

Department of Ophthalmology, Weill Cornell Medical College, 1305 York Avenue, 11th Floor, New York, NY 10021, USA.

Purpose: To determine the relationship between retinal ischaemia and the presence of macular oedema (DMO) in patients with diabetic retinopathy (DR) using ultra-widefield fluorescein angiography (UWFA) imaging.

Methods: A retrospective review of 122 eyes of 70 treatment-naïve diabetic patients who underwent diagnostic UWFA using the Optos 200Tx imaging system. Two independent, masked graders quantified the area of retinal ischaemia. Based on clinical examination and optical coherence tomography (OCT), each patient was given a binary classification as either having DMO or no DMO. McNemar's test (with Yates' correction as indicated) and a two-sample test of proportions were used to determine the relationship between DMO and ischaemia for binary and proportional data, respectively. Linear and logistic models were constructed using generalised estimating equations to test relationships between independent variables, covariates and outcomes while controlling for inter-eye correlation, age, gender, haemoglobin A1c, mean arterial pressure and dependence on insulin.

Results: Seventy-six eyes (62%) exhibited areas of retinal ischaemia. There was a significant direct correlation between DMO and peripheral retinal ischaemia as seen on UWFA (p<0.001). In addition, patients with retinal ischaemia had 3.75 times increased odds of having DMO compared with those without retinal ischaemia (CI 1.26 to 11.13, p<0.02).

Conclusion: Retinal ischaemia is significantly correlated with DMO in treatment-naïve patients with DR. UWFA is a useful tool for detecting peripheral retinal ischaemia, which may have direct implications in the diagnosis, follow-up and treatment such as targeted peripheral photocoagulation.
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http://dx.doi.org/10.1136/bjophthalmol-2011-300774DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3329634PMC
May 2012

Ultra-wide-field angiography improves the detection and classification of diabetic retinopathy.

Retina 2012 Apr;32(4):785-91

Department of Ophthalmology, Weill Cornell Medical Center, New York, NY, USA.

Purpose: To evaluate patients with diabetic retinopathy using ultra-wide-field fluorescein angiography and to compare the visualized retinal pathology with that seen on an overly of conventional 7 standard field (7SF) imaging.

Methods: Two hundred and eighteen eyes of 118 diabetic patients who underwent diagnostic fluorescein angiography using the Optos Optomap Panoramic 200A imaging system were included. The visualized area of the retina, retinal nonperfusion, retinal neovascularization, and panretinal photocoagulation were quantified by two independent masked graders. The respective areas identified on the ultra-wide-field fluorescein angiography image were compared with an overly of a modified 7SF image as outlined in the Early Treatment Diabetic Retinopathy Study.

Results: Ultra-wide-field fluorescein angiograms imaging, on average, demonstrated 3.2 times more total retinal surface area than 7SF. When compared with 7SF, ultra-wide-field fluorescein angiography showed 3.9 times more nonperfusion (P < 0.001), 1.9 times more neovascularization (P = 0.036), and 3.8 times more panretinal photocoagulation (P < 0.001). In 22 eyes (10%), ultra-wide-field fluorescein angiography demonstrated retinal pathology (including nonperfusion and neovascularization) not evident in an 7SF overly.

Conclusion: Compared with conventional 7SF imaging, ultra-wide-field fluorescein angiography reveals significantly more retinal vascular pathology in patients with diabetic retinopathy. Improved retinal visualization may alter the classification of diabetic retinopathy and may therefore influence follow-up and treatment of these patients.
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http://dx.doi.org/10.1097/IAE.0b013e3182278b64DOI Listing
April 2012

Evaluation of vascular disease progression in retinopathy of prematurity using static and dynamic retinal images.

Am J Ophthalmol 2012 Mar 22;153(3):544-551.e2. Epub 2011 Oct 22.

Department of Ophthalmology, Weill-Cornell Medical College, New York, New York, USA.

Purpose: To measure accuracy and speed for detection of vascular progression in retinopathy of prematurity (ROP) from serial images. Two strategies are compared: static side-by-side presentation and dynamic flickering of superimposed image pairs.

Design: Prospective comparative study.

Methods: Fifteen de-identified, wide-angle retinal image pairs were taken from infants who eventually developed plus disease. Image pairs representing vascular disease progression were taken ≥1 week apart, and control images without progression were taken on the same day. Dynamic flickering pairs were created by digital image registration. Ten experts independently reviewed each image pair on a secure website using both strategies, and were asked to identify progression or state that images were identical. Accuracy and speed were measured, using examination date and ophthalmoscopic findings as a reference standard.

Results: Using static images, experts were accurate in a mean (%) ± standard deviation (SD) of 11.4 of 15 (76%) ± 1.7 image pairs. Using dynamic flickering images, experts were accurate in a mean (%) ± SD of 11.3 of 15 (75%) ± 1.7 image pairs. There was no significant difference in accuracy between these strategies (P = .420). Diagnostic speed was faster using dynamic flickering (24.7 ± 8.3 seconds) vs static side-by-side images (40.3 ± 18.3 seconds) (P = .002). Experts reported higher confidence when interpreting dynamic flickering images (P = .001).

Conclusions: Retinal imaging provides objective documentation of vascular appearance, with potentially improved ability to recognize ROP progression compared to standard ophthalmoscopy. Speed of identifying vascular progression was faster by review of dynamic flickering image pairs than by static side-by-side images, although there was no difference in accuracy.
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http://dx.doi.org/10.1016/j.ajo.2011.08.030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3266465PMC
March 2012

Volumetric three-dimensional reconstruction and segmentation of spectral-domain OCT.

Ophthalmic Surg Lasers Imaging 2011 Jul;42 Suppl:S116-20

Department of Ophthalmology and HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Cornell Medical College, New York, NY, USA.

Despite advances in optical coherence tomography (OCT), three-dimensional (3D) renderings of OCT images remain limited to scanning consecutive two-dimensional (2D) OCT slices. The authors describe a method of reconstructing 2D OCT data for 3D retinal analysis and visualization in a Computer Assisted Virtual Environment (CAVE). Using customized signal processing software, raw data from 2D slice-based spectral-domain OCT images were rendered into high-resolution 3D images for segmentation and quantification analysis. Reconstructed OCT images were projected onto a four-walled space and viewed through stereoscopic glasses, resulting in a virtual reality perception of the retina. These 3D retinal renderings offer a novel method for segmentation and isolation of volumetric images. The ability to manipulate the images in a virtual reality environment allows visualization of complex spatial relationships that may aid our understanding of retinal pathology. More importantly, these 3D retinal renderings can be viewed, manipulated, and analyzed on traditional 2D monitors independent of the CAVE.
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http://dx.doi.org/10.3928/15428877-20110627-11DOI Listing
July 2011

Detection of retinal changes in Parkinson's disease with spectral-domain optical coherence tomography.

Clin Ophthalmol 2010 Dec 6;4:1427-32. Epub 2010 Dec 6.

Department of Ophthalmology, Weill Cornell Medical College, New York, NY, USA.

Purpose: This pilot study investigated whether high-resolution spectral-domain optical coherence tomography (SD-OCT) could detect differences in inner retinal layer (IRL), peripapillary retinal nerve fiber layer (RNFL), and macular thickness between patients with Parkinson's disease (PD) and controls.

Methods: Both eyes of patients with PD and age-matched controls were imaged with the Heidelberg Spectralis(®) HRA + OCT. RNFL, IRL, and macular thickness were measured for each eye using Heidelberg software. These measurements were compared with validated, published normal values for macular and RNFL thickness, and compared with matched controls for IRL thickness.

Results: Eighteen eyes from nine subjects with PD and 19 eyes of 16 control subjects were evaluated using SD-OCT. The average age of PD patients was 64 years with a range of 52-75 years. The average age of controls was 67 years with a range of 50-81 years. No significant reduction in IRL thickness was detected between PD patients and age-matched controls at 13 points along a 6 mm horizontal section through the fovea. No significant difference in RNFL thickness was detected between PD patients and published normal values. Overall average RNFL thickness was 97 μm for PD patients, which exactly matched the normative database value. However, significant differences in macular thickness were detected in three of nine subfields between PD subjects and published normal values. In PD subjects, the outer superior subfield was 2.8% thinner (P = 0.026), while the outer nasal and inner inferior subfields were 2.8% (P = 0.016) and 2.7% (P = 0.001) thicker compared to published normal values.

Conclusion: In this pilot study, significant differences in macular thickness were detected in three of nine subfields by SD-OCT. However, SD-OCT did not detect significant reductions in peripapillary RNFL and IRL thickness between PD patients and controls. This suggests that macular thickness measurements by SD-OCT may potentially be used as an objective, noninvasive, and easily quantifiable in vivo biomarker in PD. Larger, longitudinal studies are needed to explore these relationships further.
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http://dx.doi.org/10.2147/OPTH.S15136DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3000768PMC
December 2010

Treatment of noninfectious posterior uveitis with dexamethasone intravitreal implant.

Clin Ophthalmol 2010 Dec 6;4:1423-6. Epub 2010 Dec 6.

Department of Ophthalmology, Weill Cornell Medical Center, New York, NY, USA.

Purpose: To report our experience with dexamethasone 0.7 mg sustained-release intravitreal implant (Ozurdex(®); Allergan, Inc, Irvine, CA) in noninfectious posterior uveitis.

Methods: A retrospective chart review of patients with noninfectious uveitis treated with sustained-release dexamethasone 0.7 mg intravitreal implant was performed. Complete ophthalmic examination including signs of inflammatory activity, visual acuity, fundus photography, fluorescein angiography, optical coherence tomography, and tolerability of the implant were assessed.

Results: Six eyes of 4 consecutive patients treated with a total of 8 dexamethasone 0.7 mg sustained-release intravitreal implants for posterior noninfectious uveitis were included. Two patients presented with unilateral idiopathic posterior uveitis; 2 patients had bilateral posterior uveitis, one secondary to sarcoidosis and the other to Vogt-Koyanagi-Harada syndrome. All eyes showed clinical and angiographic evidence of decreased inflammation following implant placement. Mean follow-up time post-injection was 5.25 months. Four eyes received 1 and 2 eyes received 2 Ozurdex implants during the follow-up period. The duration of effect of the implant was 3 to 4 months. No serious ocular or systemic adverse events were noted during the follow-up period.

Conclusions: In patients with noninfectious posterior uveitis, sustained-release dexamethasone 0.7 mg intravitreal implant may be an effective treatment option for controlling intraocular inflammation.
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http://dx.doi.org/10.2147/OPTH.S15696DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3000767PMC
December 2010

Retinal nerve fiber layer evaluation in multiple sclerosis with spectral domain optical coherence tomography.

Clin Ophthalmol 2010 Sep 20;4:1007-13. Epub 2010 Sep 20.

Departments of Ophthalmology, Weill Cornell Medical College, New York, NY, USA.

Purpose: Histopathologic studies have reported retinal nerve fiber layer (RNFL) thinning in various neurodegenerative diseases. Attempts to quantify this loss in vivo have relied on time-domain optical coherence tomography (TDOCT), which has low resolution and requires substantial interpolation of data for volume measurements. We hypothesized that the significantly higher resolution of spectral-domain optical coherence tomography (SDOCT) would better detect RNFL changes in patients with multiple sclerosis, and that RNFL thickness differences between eyes with and without optic neuritis might be identified more accurately.

Methods: In this retrospective case series, patients with multiple sclerosis were recruited from the Judith Jaffe Multiple Sclerosis Center at Weill Cornell Medical College in New York. Patients with a recent clinical diagnosis of optic neuritis (less than three months) were excluded. Eyes with a history of glaucoma, optic neuropathy (other than multiple sclerosis-related optic neuritis), age-related macular degeneration, or other relevant retinal and/or optic nerve disease were excluded. Both eyes of each patient were imaged with the Heidelberg Spectralis(®) HRA + OCT. RNFL and macular thickness were measured for each eye using the Heidelberg OCT software. These measurements were compared with validated published normal values, and were modeled as linear functions of duration of disease. The odds of an optic neuritis diagnosis as a function of RNFL and macular thickness were calculated.

Results: Ninety-four eyes were prospectively evaluated using OCT. Ages of patients ranged from 26 to 69 years, with an average age of 39 years. Peripapillary RNFL thinning was demonstrated in multiple sclerosis patients; mean RNFL thickness was 88.5 μm for individuals with multiple sclerosis compared with a reported normal value of 97 μm (P < 0.001). Eyes with a history of optic neuritis had more thinning compared with those without optic neuritis (83.0 μm versus 90.5 μm, respectively, P = 0.02). No significant differences were observed in macular thickness measurements between eyes with and without optic neuritis, nor were macular thickness measurements significantly different from normal values. As a function of multiple sclerosis duration and controlling for age, RNFL thickness was decreased in patients with a duration of multiple sclerosis greater than five years compared with those with a duration less than or equal to one year (P = 0.008).

Conclusions: Patients with a history of multiple sclerosis had RNFL thinning that was detectable on SDOCT. Decreasing RNFL thickness in eyes with optic neuritis was found, and the odds of having optic neuritis were increased significantly with decreasing RNFL thickness. Average RNFL thinning with increasing duration of disease was an excellent predictor of a reported history of optic neuritis. SDOCT retinal imaging may represent a high-resolution, objective, noninvasive, and easily quantifiable in vivo biomarker of the presence of optic neuritis and severity of multiple sclerosis.
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http://dx.doi.org/10.2147/opth.s13278DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2946989PMC
September 2010

Results and risk factors for recurrence following single-level tubular lumbar microdiscectomy.

J Neurosurg Spine 2010 Jun;12(6):680-6

Department of Neurosurgery, Yale University School of Medicine, Yale-New Haven Hospital, New Haven, Connecticut, USA.

Object: The use of minimally invasive surgical techniques, including microscope-assisted tubular lumbar microdiscectomy (tLMD), has gained increasing popularity in treating lumbar disc herniations (LDHs). This particular procedure has been shown to be both cost-efficient and effective, resulting in outcomes comparable to those of open surgical procedures. Lumbar disc herniation recurrence necessitating reoperation, however, remains an issue following spinal surgery, with an overall reported incidence of approximately 3-13%. The authors' aim in the present study was to report their experience using tLMD for single-level LDH, hoping to provide further insight into the rate of surgical recurrence and to identify potential risk factors leading to this complication.

Methods: The authors retrospectively reviewed the cases of 217 patients who underwent tLMD for single-level LDH performed identically by 2 surgeons (J.B., R.H.) between 2004 and 2008. Evaluation for LDH recurrence included detailed medical chart review and telephone interview. Recurrent LDH was defined as the return of preoperative signs and symptoms after an interval of postoperative resolution, in conjunction with radiographic demonstration of ipsilateral disc herniation at the same level and pathological confirmation of disc material. A cohort of patients without recurrence was used for comparison to identify possible risk factors for recurrent LDH.

Results: Of the 147 patients for whom the authors were able to definitively assess symptomatic recurrence status, 14 patients (9.5%) experienced LDH recurrence following single-level tLMD. The most common level involved was L5-S1 (42.9%) and the mean length of time to recurrence was 12 weeks (range 1.5-52 weeks). Sixty-four percent of the patients were male. In a comparison with patients without recurrence, the authors found that relatively lower body mass index was significantly associated with recurrence (p = 0.005), such that LDH in nonobese patients was more likely to recur.

Conclusions: Recurrence rates following tLMD for LDH compare favorably with those in patients who have undergone open discectomy, lending further support for its effectiveness in treating single-level LDH. Nonobese patients with a relatively lower body mass index, in particular, appear to be at greater risk for recurrence.
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http://dx.doi.org/10.3171/2009.12.SPINE08843DOI Listing
June 2010
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