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Annie Chan

Publications and source records attributed to Annie Chan.

10 recordsLinked to original sources
PubMed2006

Ultra-high resolution optical coherence tomography assessment of photoreceptors in retinitis pigmentosa and related diseases.

PURPOSE: To assess photoreceptor integrity in patients with retinitis pigmentosa (RP) and related diseases using ultra-high resolution optical coherence tomography (UHR-OCT) and to correlate foveal photoreceptor loss with visual acuity. DESIGN: Observational case series. METHODS: Nine eyes of nine patients with RP and related diseases were imaged with UHR-OCT at the ophthalmology clinic. Patients were diagnosed based on history, examination, fluorescein angiography, and electroretinography. Concurrently, 36 eyes of 36 normal subjects were imaged with UHR-OCT. Central foveal thickness (CFT) and foveal outer segment/pigment epithelium thickness (FOSPET) were defined and measured on UHR-OCT images in all subjects and were compared between the two groups using unpaired t tests. The two thickness measurements in RP patients were correlated with visual acuity using Pearson correlation and linear regression. RESULTS: UHR-OCT demonstrated macular photoreceptor thinning in all RP patients. The difference in CFT between RP patients and normal subjects was not statistically significant (P = .103), but the difference in FOSPET between the two groups was significant (P = .003). Visual acuity showed a fair correlation with CFT (Pearson r = -0.43, r(2) = 0.187, P = .245) and an excellent correlation with FOSPET (Pearson r = -0.942, r(2) = 0.887, P < .0001). CONCLUSIONS: In the current study using UHR-OCT, a new thickness measurement termed FOSPET is demonstrated to quantify photoreceptor loss. FOSPET was statistically thinner in patients with RP and related diseases than in normal eyes and showed correlation with logMAR visual acuity. FOSPET appears to be a probable predictor of visual acuity in RP.

Adult↗
PubMed2006

Normal macular thickness measurements in healthy eyes using Stratus optical coherence tomography.

OBJECTIVE: To report normal macular thickness measurements in healthy eyes using the latest commercially available optical coherence tomography (OCT) mapping software, version 3.0, from the Stratus OCT (OCT3). METHODS: Thirty-seven eyes from 37 healthy subjects underwent a complete ophthalmologic examination, including OCT. Six radial scans, 6 mm in length and centered on the fovea, were obtained using the OCT3. Retinal thickness was automatically calculated by OCT mapping software. Measurements were displayed as the mean and standard deviation for each of the 9 regions defined in the Early Treatment Diabetic Retinopathy Study. RESULTS: Foveal thickness (mean thickness in the central 1000-microm diameter area) and central foveal thickness (mean thickness at the point of intersection of 6 radial scans) on the OCT3 were 212 +/- 20 and 182 +/- 23 microm, respectively. Macular thickness measurements were thinnest at the center of the fovea, thickest within 3-mm diameter of the center, and diminished toward the periphery of the macula. The temporal quadrant was thinner than the nasal quadrant. Central foveal thickness was also manually determined as 170 +/- 18 microm, approximately 12 microm less than the value automatically obtained from the OCT3 software. There was no correlation between age and foveal thickness (P = .80). CONCLUSIONS: Mean foveal thickness measurements were 38 to 62 microm thicker than previously reported values, while mean central foveal thickness measurements were 20 to 49 microm thicker than previously published values. This discrepancy should be considered when interpreting OCT scans.

Adult↗
PubMed2006

Ultrahigh-resolution optical coherence tomography of surgically closed macular holes.

OBJECTIVE: To evaluate retinal anatomy using ultrahigh-resolution optical coherence tomography (OCT) in eyes after successful surgical repair of full-thickness macular hole. METHODS: Twenty-two eyes of 22 patients were diagnosed as having macular hole, underwent pars plana vitrectomy, and had flat/closed macular anatomy after surgery, as confirmed with biomicroscopic and OCT examination findings. An ultrahigh-resolution-OCT system developed for retinal imaging, with the capability to achieve approximately 3-microm axial resolution, was used to evaluate retinal anatomy after hole repair. RESULTS: Despite successful closure of the macular hole, all 22 eyes had macular abnormalities on ultrahigh-resolution-OCT images after surgery. These abnormalities were separated into the following 5 categories: (1) outer foveal defects in 14 eyes (64%), (2) persistent foveal detachment in 4 (18%), (3) moderately reflective foveal lesions in 12 (55%), (4) epiretinal membranes in 14 (64%), and (5) nerve fiber layer defects in 3 (14%). CONCLUSIONS: With improved visualization of fine retinal architectural features, ultrahigh-resolution OCT can visualize persistent retinal abnormalities despite anatomically successful macular hole surgery. Outer foveal hyporeflective disruptions of the junction between the inner and outer segments of the photoreceptors likely represent areas of foveal photoreceptor degeneration. Moderately reflective lesions likely represent glial cell proliferation at the site of hole reapproximation. Thin epiretinal membranes do not seem to decrease visual acuity and may play a role in reestablishing foveal anatomy after surgery.

Aged↗
PubMed2005

Idiopathic juxtafoveal retinal telangiectasis: new findings by ultrahigh-resolution optical coherence tomography.

OBJECTIVE: To investigate the capabilities of ultrahigh-resolution optical coherence tomography (UHR OCT); to compare with the commercially available OCT standard-resolution system, StratusOCT, for imaging of idiopathic juxtafoveal retinal telangiectasis (IJT); and to demonstrate that UHR OCT provides additional information on disease morphology, pathogenesis, and management. DESIGN: Retrospective, observational, interventional case series. PARTICIPANTS: Nineteen eyes of 10 patients diagnosed with IJT in at least one eye. METHOD: All patients were imaged with UHR OCT and StratusOCT at the same visit. A subset of patients was also imaged before and after treatment of IJT. MAIN OUTCOME MEASURES: Ultrahigh- and standard-resolution cross-sectional tomograms of IJT pathology. RESULTS: Using both standard- and ultrahigh-resolution OCT, we identified the following features of IJT: (1) a lack of correlation between retinal thickening on OCT and leakage on fluorescein angiography, (2) loss and disruption of the photoreceptor layer, (3) cystlike structures in the foveola and within internal retinal layers such as the inner nuclear or ganglion cell layers, (4) a unique internal limiting membrane draping across the foveola related to an underlying loss of tissue, (5) intraretinal neovascularization near the fovea, and (6) central intraretinal deposits and plaques. In 63% of cases, the presence of abnormal vessels and a discontinuity of the photoreceptor layer correlated with visual acuity. CONCLUSIONS: Ultrahigh-resolution OCT improves visualization of the retinal pathology associated with IJT and allows identification of new features associated with it. Some of these features, such as discontinuity of the photoreceptor layer, are revealed only by UHR OCT.

Adult↗
PubMed2005

A standardized method for reporting changes in macular thickening using optical coherence tomography.

OBJECTIVE: To describe a standardized method for reporting quantitative changes in macular thickening using optical coherence tomography (OCT). METHODS: The proposed method consists of calculating the actual change in central foveal thickening (the initial pretreatment thickness minus the posttreatment thickness) using OCT and dividing that value by the potential change (the initial pretreatment thickness minus the normal thickness based on normative data) to provide the total improvement in macular edema as a percentage. We refer to this method as the standardized change in macular thickening (SCMT). To illustrate the effectiveness of this method, we performed a retrospective review of 2 studies that evaluated different strategies for treating refractory macular edema. RESULTS: Patients treated with intravitreal triamcinolone acetonide for refractory diabetic macular edema had an overall SCMT of approximately 75%, 78%, and 55% at the 1-, 3-, and 6-month follow-up visits, respectively. More than half of the patients in the study cohort (9 of 16 patients) experienced greater than 80% SCMT at the last follow-up visit. Patients who underwent vitrectomy for a taut, thickened posterior hyaloid on OCT responded with an SCMT of approximately 78% at the 3-month follow-up visit and 87% at the final follow-up visit (mean, 19 months). Patients who underwent vitrectomy for diabetic macular edema unresponsive to laser photocoagulation but with no evidence of vitreomacular traction experienced an SCMT of 37% at the 3-month follow-up visit and 20% at the final follow-up visit (mean, 17 months). CONCLUSION: The proposed method offers an objective and intuitive basis for evaluating and comparing the efficacy of different therapeutic modalities.

Diabetic Retinopathy↗
PubMed2004

Stage 0 macular holes: observations by optical coherence tomography.

OBJECTIVE: To introduce the concept of a stage 0 macular hole based on optical coherence tomographic observations of the vitreoretinal interface in fellow eyes of patients with unilateral idiopathic macular holes, and to evaluate the subsequent risk of progression to a full-thickness macular hole. DESIGN: Retrospective observational case series. PARTICIPANTS: Ninety-four patients with a unilateral stage 2, 3, or 4 full-thickness macular hole. METHODS: The medical records of patients with a unilateral macular hole diagnosed between 1994 and 2000 at the New England Eye Center were reviewed. MAIN OUTCOME MEASURE: Development of a full-thickness macular hole in the fellow eye on biomicroscopic fundoscopy or optical coherence tomography (OCT). RESULTS: In 27 (28.7%) of 94 clinically normal fellow eyes, OCT detected an abnormality of the vitreoretinal interface but normal foveal anatomy. The vitreoretinal abnormalities were further subclassified into severe (4 eyes), moderate (8 eyes), and mild (15 eyes) based on the intensity and morphology of the OCT signal. One of the 4 (25%) severe cases progressed to a full-thickness macular hole, 4 of the 8 (50%) moderate cases became full-thickness macular holes, and no (0%) mild cases progressed to a full-thickness macular hole. Severe and moderate eyes seemed to share characteristic features on OCT that increased their risk of macular hole development (stage 0 macular hole). The macular hole-free survival at 48 months was 94% for stage 0-negative patients, versus 54% for stage 0-positive patients. Univariate analysis revealed that the presence of a stage 0 macular hole was significantly associated with an almost 6-fold increase in the risk of macular hole formation (relative risk: 5.8, 95% confidence interval: 1.16-28.61, P = 0.03). CONCLUSIONS: A stage 0 macular hole has a normal biomicroscopic appearance clinically, but has salient features on OCT as a result of oblique vitreous traction. Optical coherence tomographic findings consist of a normal foveal contour and normal retinal thickness and must include the presence of a preretinal, minimally reflective, thin band inserting obliquely on at least one side of the fovea. The presence of a stage 0 macular hole in the fellow eye is a significant risk factor for the development of a second macular hole.

Adult↗
PubMed2003

Lymphoma of the nasal cavity and paranasal sinuses: treatment and outcome of early-stage disease.

The records of 23 patients diagnosed and treated at the Massachusetts General Hospital for extranodal non-Hodgkin's lymphoma of the paranasal sinus and nasal cavity were reviewed. The majority of patients were Ann Arbor stage I and approximately evenly divided in T1 or T2 (n = 10) and T3 or T4 (n = 13). Eight patients had nasal-type NK/T cell and 15 patients had diffuse large B-cell lymphoma (DLBCL). The patients with nasal-type NK/T cell lymphoma predominately involved the nasal cavity (5/8), whereas the DLBCL more often had the paranasal sinuses as the primary site (12/15). All patients received radiation as part of their treatment. Only three patients received chemotherapy as part of their initial treatment for three cycles using a cyclophosphamide, doxorubicin, vincristine, and prednisone-based regimen. By coincidence, the estimated overall survival (OS) and disease-free survival rates for both 5 and 10 years were all the same for all analyses. The OS for the entire group at 10 years was 78%. Significant prognostic factors were Ann Arbor stage IEA versus IIEA ( p = 0.0001) and T stage with (T1 or T2) versus (T3 or T4) (p = 0.0243). Combining Ann Arbor stage and T stage created a highly significant prognostic variable (IEA & [T1 or T2], IEA & [T3 or T4], IIEA & [T1 or T2], IIEA & [T3 or T4]) at p = 0.0001, regardless of site or histology. Patients with local-regional disease appear to be well controlled with radiation alone, but distant failure remains a problem. A combined-modality approach with local-regional radiation and systemic chemotherapy is recommended for these patients.

Adult↗
PubMedDate not supplied

Quantification of photoreceptor layer thickness in normal eyes using optical coherence tomography.

OBJECTIVE: To demonstrate the ability to segment and analyze individual intraretinal layers, including the outer retinal complex (ORC; outer nuclear layer and inner and outer segments of the photoreceptor cells), in healthy eyes using images acquired from the latest commercially available optical coherence tomography (OCT) system (StratusOCT; Carl Zeiss Meditec, Inc., Dublin, CA) and from the ultrahigh resolution OCT (UHR-OCT) prototype. METHODS: Thirty-seven eyes from 37 healthy subjects underwent complete ophthalmologic examination using StratusOCT and UHR-OCT. ORC was identified and measured using a segmentation algorithm. RESULTS: For StratusOCT, mean weighted ORC thickness +/- SD was 91.1 +/- 7.9 microm, and mean weighted total retinal thickness +/- SD was determined to be 258.9 +/- 10.1 microm. For UHR-OCT, mean weighted ORC thickness +/- SD was 96.4 +/- 6.3 microm, and mean weighted total retinal thickness +/- SD was determined to be 263.4 +/- 9.2 mum. There was a higher rate of algorithm failure with UHR-OCT images. CONCLUSIONS: Photoreceptor layer thickness can be calculated by measuring ORC on OCT images using a macular segmentation algorithm. ORC values may serve as a useful objective parameter in determining the efficacy of various therapeutic modalities that target the photoreceptor layer in various diseases.

Adult↗