Helen K Li

University of Texas Health Science Center at Houston, Houston, TX, United States

Are you Helen K Li?

Claim your profile

Publications (12)35.65 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To compare agreement between mosaicked and seven field photographs for classification of the diabetic retinopathy (DR) severity. Mosaic digital (MosD) images were compared with seven field stereo film (7FF) and stereo digital (7FD) photographs from a 152-eye cohort with full-spectrum Early Treatment of Diabetic Retinopathy severity levels for agreement on severity level, DR presence with ascending severity thresholds, DR index lesion presence, and classification repeatability. There was a substantial agreement classifying the Early Treatment Diabetic Retinopathy Study DR severity level between MosD and 7FF (kunweighted = 0.59, klinear weighted = 0.83), MosD and 7FD (κ = 0.62, κ weighted = 0.86), and 7FD and 7FF (κ = 0.62, κ weighted = 0.86) images. Marginal homogeneity analyses found no significant difference between MosD and 7FF (P = 0.44, Bhapkar's test). Kappa between MosD and 7FF ranged from 0.75 to 0.91 for the presence or absence of DR at 8 ascending severity thresholds. Repeatability among readers using MosD images was similar to repeatability among those using 7FF or 7FD. Repeatability among readers using MosD and 7FF images at various severity thresholds was similar. Kappa between MosD and 7FF grading for identifying DR lesions ranged from 0.61 to 1.00. Mosaic images are generally comparable with standard seven-field photographs for classifying DR severity.
    Retina (Philadelphia, Pa.) 04/2011; 31(8):1553-63. · 2.93 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate digital photography parameters affecting comparability with the Early Treatment Diabetic Retinopathy Study (ETDRS) film protocol for diabetic retinopathy (DR) severity grading. ETDRS protocol photographs and four variations of digital images (uncompressed stereoscopic, compressed stereoscopic, uncompressed monoscopic, and uncompressed monoscopic wide-angle mosaic) of 152 eyes were independently evaluated by using ETDRS classifications. Digital formats were compared to film and each other for agreement on severity level, DR presence at ascending threshold, presence of the DR index lesion, and repeatability of grading. Study parameters included image resolution sufficient to distinguish small lesions, color balancing of digital images to film, documenting essential ETDRS classification retinal regions, similar magnification, and supplementary green-channel viewing. The κ statistic was substantial or near substantial between all digital formats and film for classifying severity levels (κ = 0.59-0.62; κ(w) [linear weighted] = 0.83-0.87). The distribution of DR levels in all digital formats was not significantly different from that of the film (Bhapkar test, P = 0.09-0.44). The κ among digital formats for severity level was also substantial or near substantial (κ = 0.58-0.76, κ(w) = 0.82-0.92). Differences between digital formats and film for grading severity level, severity threshold, or index lesions were not significant. The repeatability of grading between readers using film and all digital formats was also similar. Digital format variations compared favorably with film for DR classification. Translating film characteristics (resolution, color/contrast) and protocol (magnification, retinal regions) to digital equivalents and augmentation of full color with green-channel viewing most likely contributed to the results.
    Investigative ophthalmology & visual science 02/2011; 52(7):4717-25. · 3.43 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To assess agreement between evaluations of monoscopic and stereoscopic digital images versus stereo film photographs in diabetic macular edema (DME). A 152-eye group of digital monoscopic macular images (seven-field sets and wide-angle mosaics) were compared with digital stereoscopic images (uncompressed and compressed seven-field sets) and stereo 35-mm film photos (Early Treatment Diabetic Retinopathy Study protocol) for the presence of hard exudates (HE), retinal thickening (RT), clinically significant macular edema (CSME), and RT at the center of the macular (RTCM). Agreement, according to the κ statistic, was almost perfect in identifying HE and RT between all digital formats and stereo film (HE, κ = 0.81-0.87; RT, κ = 0.87-0.92). Distribution in all digital formats was not significantly different from that in film (Bhapkar test: HE, P = 0.20-0.40; RT, P = 0.06-1.0). CSME and RTCM grading differences were either significant or trended toward significance. The readers detected CSME and RTCM in film images more often than in digital formats. In identifying DME features, agreement between evaluations of monoscopic digital formats and film was similar to that between stereo digital formats and film, and the performance of uncompressed images versus film was similar to that of compressed images versus film. Repeatability between readers was similar in evaluations of film and all digital formats. Repeatability in identifying RTCM was lower than that of other DME components in film and all digital formats. Stereoscopic digital formats are equivalent to monoscopic for DME evaluation, but digital photography is not as sensitive as film in detecting CSME and RTCM.
    Investigative ophthalmology & visual science 12/2010; 51(12):6753-61. · 3.43 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To assess agreement between digital and film photography for research classification of diabetic retinopathy severity. Digital and film photographs from a 152-eye cohort with a full spectrum of Early Treatment Diabetic Retinopathy Study (ETDRS) severity levels were assessed for repeatability of grading within each image medium and for agreement on ETDRS discrete severity levels, ascending severity thresholds, and presence or absence of diabetic retinopathy index lesions, between digital and 35-mm slides (film). Digital photographs were color balanced to match film. There was substantial agreement (κ = 0.61, κ(w) [linear weighted] = 0.87) in classification of ETDRS diabetic retinopathy severity levels between digital images and film. Marginal homogeneity analyses found no significant difference in frequency distributions on the severity scale (P = 0.21, Bhapkar test). The κ results ranged from 0.72 to 0.95 for presence or absence of eight ascending diabetic retinopathy severity thresholds. Repeatability of grading between readers viewing digital images was equal to or better than that obtained with film (pair-wise interreader κ for digital images ranged from 0.47 to 0.57 and for film from 0.43 to 0.57. The κ results for identifying diabetic retinopathy lesions ranged from moderate to almost perfect. Moderate agreement of intraretinal microvascular abnormalities and venous beading between digital images and film accounted for slightly lower concordance for severity thresholds ≥47 and for slightly lower interreader agreement within digital and film images at severity thresholds ≥43 and ≥47. Under controlled circumstances, digital photography can equal the reliability of 35-mm slides for research classification of ETDRS severity level.
    Investigative ophthalmology & visual science 11/2010; 51(11):5846-52. · 3.43 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To compare research grading of diabetic retinopathy (DR) severity level from compressed digital images versus uncompressed images and film. Compressed (JPEG2000, 37:1) digital images (C) were compared with uncompressed digital (U) and film (F) stereoscopic photographs from a 152-eye cohort with full-spectrum Early Treatment Diabetic Retinopathy Study severity levels for agreement on severity level, DR presence with ascending severity threshold, presence of DR index lesions, and repeatability of grading. Classification of Early Treatment Diabetic Retinopathy Study severity levels from C images agreed substantially with results from F images (κ = 0.60, κ(w) [linear weighted] = 0.86) and uncompressed digital images (κ = 0.76, κ(w) = 0.92). For agreement of uncompressed digital versus F images, κ = 0.62 and κ(w) = 0.86. Distribution of Early Treatment Diabetic Retinopathy Study levels was not significantly different between C and F images (P = 0.09, Bhapkar's test for marginal homogeneity). For presence/absence of DR at 8 ascending severity thresholds, agreement between C and F was "almost perfect" (κ ≥ 0.8). Agreement on severity level between readers with C images was at least as good as that with uncompressed digital image or F. Repeatability of severity threshold grading between readers was similar using C or F images. For identifying individual DR lesions, agreement between C and F ranged from "moderate" to "perfect." Agreement of grading venous beading from C was slightly lower than from F. Full Early Treatment Diabetic Retinopathy Study scale DR severity level grading using C images is comparable to that using U images or film.
    Retina (Philadelphia, Pa.) 10/2010; 30(10):1651-61. · 2.93 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To assess agreement between monoscopic and stereoscopic photography for research classification of the severity of diabetic retinopathy (DR). Monoscopic digital (MD) images were compared with stereo digital (SD) and film (SF) photographs from a 152-eye cohort with full-spectrum Early Treatment Diabetic Retinopathy Study (ETDRS) severity levels for agreement on severity level, DR presence with ascending severity threshold, presence of DR index lesions, and repeatability of grading. There was substantial agreement classifying ETDRS DR severity levels between MD and SF (kappa = 0.65, kappa(w) [linear weighted] = 0.87), MD and SD (kappa = 0.66, kappa(w) = 0.87), and SD and SF (kappa = 0.62, kappa(w) = 0.86) images. Marginal homogeneity analyses found no significant difference between MD and SF images (P = 0.53, Bhapkar test). The kappa agreement between MD and SF ranged from 0.80 to 0.94 for the presence or absence of eight ascending DR severity thresholds. Repeatability between the readers of the MD images was equal to or better than that of the readers of SD or SF images. Severity threshold grading repeatability between readers was similar with the MD and SF images. The kappa agreement between MD and SF for identifying diabetic retinopathy lesions ranged from moderate to almost perfect. The kappa comparisons showed that performance of grading new vessels on the disc in MD images was slightly lower than that with the SF images. Monoscopic photography can equal the reliability of stereo photography for full ETDRS DR severity scale grading.
    Investigative ophthalmology & visual science 06/2010; 51(6):3184-92. · 3.43 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We report a ciliary body melanoma that apparently arose from a melanocytoma in a 15-year-old black teenager. The eye was enucleated, and metastatic evaluation remained negative at 5 years' follow-up. This unusual case, confirmed histopathologically, reveals that young patients with melanocytoma can have malignant transformation at an early age.
    Journal of AAPOS: the official publication of the American Association for Pediatric Ophthalmology and Strabismus / American Association for Pediatric Ophthalmology and Strabismus 04/2010; 14(2):178-80. · 1.07 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Evaluation of clinical features and natural course of giant choroidal nevi (diameter >or=10 mm). Retrospective observational case series. We included 322 eyes of 322 patients. Clinic-based study of tumor features, tumor outcome, and vision outcome. Kaplan-Meier analysis was used to assess time to transformation into melanoma. Cox proportional hazards regressions evaluated clinical factors predictive of nevus transformation into melanoma and nevus-related decreased vision (defined as <20/20 and unrelated to other eye pathology). Transformation of giant choroidal nevus into melanoma and nevus-related decreased vision. A medical record review of 4100 patients diagnosed with choroidal nevus identified 322 (8%) giant choroidal nevi. Median nevus basal diameter was 11 mm (range, 10-24). Median thickness was 1.9 mm (range, 0-4.4). Related retinal findings included drusen overlying nevus (n = 261 [81%]), subretinal fluid (n = 26 [8%]), orange pigment (n = 4 [1%]), retinal pigment epithelial (RPE) detachment (n = 6 [2%]), hyperplasia (n = 48 [15%]), fibrous metaplasia (n = 48 [15%]), atrophy (n = 63 [20%]), or trough (n = 6 [2%]). Kaplan-Meier analysis estimated transformation into melanoma in 13% at 5 years and 18% at 10 years. Multivariate analyses revealed factors predictive of transformation into melanoma including involvement or close proximity to the foveola (P = 0.017) and acoustic hollowness (P = 0.052). Nevus-related decreased vision was found in 2.2% of eyes at initial visit and 3.7% at final visit (median 41 and mean 61 months follow-up). Factors associated with nevus-related decreased vision at initial visit included subretinal fluid (P = 0.001), involvement or close proximity to foveola (P = 0.005), RPE detachment (P = 0.033), and nevus-related choroidal neovascular membrane (P = 0.044). Factors predictive of nevus-related decreased vision at final visit included involvement or close proximity to the foveola (P = 0.001) and presence of symptoms at the initial visit (P = 0.032). Giant choroidal nevi can clinically resemble choroidal melanoma but show features of chronicity, such as overlying drusen and RPE alterations. Over time, 18% transformed into melanoma, underscoring the importance of life-long surveillance.
    Ophthalmology 12/2009; 117(2):324-33. · 5.56 Impact Factor
  • Clinical and Experimental Ophthalmology 01/2009; 36(9):895-7. · 1.96 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To explore the correlation between optical coherence tomography (OCT) and stereoscopic fundus photographs (FP) for the assessment of retinal thickening (RT) in diabetic macular edema (DME) within a clinical trial. OCT, FP, and best corrected visual acuity (VA) measurements were obtained in both eyes of 263 participants in a trial comparing two photocoagulation techniques for DME. Correlation coefficients (r) were calculated comparing RT measured by OCT, RT estimated from FP, and VA. Principal variables were central subfield retinal thickness (CSRT) obtained from the OCT fast macular map and DME severity assessed by a reading center using a seven-step photographic scale combining the area of thickened retina within 1 disc diameter of the foveal center and thickening at the center. Medians (quartiles) for retinal thickness within the center subfield by OCT at baseline increased from 236 (214, 264) microm in the lowest level of the photographic scale to 517 (455, 598) microm in the highest level (r = 0.67). However, CSRT interquartile ranges were broad and overlapping between FP scale levels, and there were many outliers. Correlations between either modality and VA were weaker (r = 0.57 for CSRT, and r = 0.47 for the FP scale). OCT appeared to be more reproducible and more sensitive to change in RT between baseline and 1 year than was FP. There was a moderate correlation between OCT and FP assessments of RT in patients with DME and slightly less correlation of either measure with VA. OCT and FP provide complementary information but neither is a reliable surrogate for VA.
    Investigative Ophthalmology &amp Visual Science 06/2008; 49(5):1745-52. · 3.44 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate optical coherence tomography (OCT) thickness of the macula in people with diabetes but minimal or no retinopathy and to compare these findings with published normative data in the literature from subjects reported to have no retinal disease. Cross-sectional study. In a multicenter community- and university-based practices setting, 97 subjects with diabetes with no or minimal diabetic retinopathy and no central retinal thickening on clinical examination and a center point thickness of 225 microm or less on OCT (Stratus OCT; Carl Zeiss Meditec, Dublin, California, USA) were recruited. Electronic Early Treatment of Diabetic Retinopathy Study best-corrected visual acuity, seven-field stereoscopic color fundus photographs, and Stratus OCT fast macular scan were noted. Main outcome measures were central subfield (CSF) thickness measured on Stratus OCT. On average, CSF thickness was 201 +/- 22 microm. CSF thickness was significantly greater in retinas from men than retinas from women (mean +/- standard deviation, 209 +/- 18 microm vs 194 +/- 23 microm; P < .001). After adjusting for gender, no additional factors were found to be associated significantly with CSF thickness (P > .10). CSF thicknesses on Stratus OCT in people with diabetes and minimal or no retinopathy are similar to thicknesses reported from a normative database of people without diabetes. CSF thickness is greater in men than in women, consistent with many, but not all, previous reports. Studies involving comparisons of retinal thickness with expected norms should consider different mean values for women and men.
    American Journal of Ophthalmology 05/2008; 145(5):894-901. · 4.02 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Six digital fundus cameras were examined to determine degrees of distortion introduced by lenses. Results quantified lens distortion effects on fundus images and demonstrate intrinsic properties in similar camera systems may vary.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2004; 2:1497-500.

Publication Stats

84 Citations
35.65 Total Impact Points

Institutions

  • 2010–2011
    • University of Texas Health Science Center at Houston
      • School of Biomedical Informatics
      Houston, TX, United States
    • University of Texas Medical Branch at Galveston
      Galveston, Texas, United States
  • 2009–2011
    • Thomas Jefferson University
      • • Department of Ophthalmology
      • • Wills Eye Institute
      Philadelphia, PA, United States