Quantitative image analysis applied to the grading of vitreous haze

The present invention includes an automated method for grading the blurring of ocular fundus images to permit automated grading of severity of vitritis. Standard fundoscopic images are converted to gray-scale images. The gray-scale images are processed through a low-pass filter to eliminate high frequency components. The low pass image is subtracted from the corresponding original image, producing the difference image. The difference image is converted to the final entropy image. The entropy image is processed using Fast Fourier Transform to calculate its power. The final blur score is calculated

Automated Method of Grading Vitreous Haze in Patients With Uveitis for Clinical Trials

Purpose: Uveitis is associated with accumulation of exudate in the vitreous, which reduces fundus visibility. The condition is assessed in patients by subjectively matching fundus photographs to a six-level (NIH) or nine-level (Miami) haze scale. This study aimed to develop an objective method of assessing vitreous haze. Methods: An image-processing algorithm was designed that quantifies vitreous haze via high-pass filtering, entropy analysis, and power spectrum integration. The algorithm was refined using nine published photographs that represent incremental levels of fundus blur and applied without further refinement to 120 random fundus photographs from a uveitis image library. Computed scores were compared against the grades of two trained readers of vitreous haze and against acutance, a generic measure of image clarity, using Cohen\u27s κ and Gwet\u27s AC statistics. Results: Exact agreement between algorithm scores and reader grades was substantial for both NIH and Miami scales (κ = 0.61 and 0.67, AC = 0.82 and 0.92). Within-one (κ = 0.78 and 0.82) and within-two (κ = 0.80 and 0.84) levels of agreement were almost perfect. The correspondence was comparable to that between readers. Whereas, exact (κ = 0.45 and 0.44, AC = 0.73 and 0.75), within-one (κ = 0.69 and 0.68), and within-two (κ = 0.73 and 0.72) levels of agreement for the two scales were moderate to substantial for acutance calculations. Conclusions: The computer algorithm produces a quantitative measure of vitreous haze that correlates strongly with the perception of expert graders. Translational Relevance: The work offers a rapid, unbiased, standardized means of assessing vitreous haze for clinical and telemedical monitoring of uveitis patients

An iterative estimating procedure for probit-type nonresponse models in surveys with call backs

Conditioned likelihood, iterative estimation, missing data, non ignorability, non response, probit models, 62A10, 62E20, 62F12, 62F30,

Automated Method of Grading Vitreous Haze in Patients With Uveitis for Clinical Trials

Purpose: Uveitis is associated with accumulation of exudate in the vitreous, which reduces fundus visibility. The condition is assessed in patients by subjectively matching fundus photographs to a six-level (NIH) or nine-level (Miami) haze scale. This study aimed to develop an objective method of assessing vitreous haze. Methods: An image-processing algorithm was designed that quantifies vitreous haze via high-pass filtering, entropy analysis, and power spectrum integration. The algorithm was refined using nine published photographs that represent incremental levels of fundus blur and applied without further refinement to 120 random fundus photographs from a uveitis image library. Computed scores were compared against the grades of two trained readers of vitreous haze and against acutance, a generic measure of image clarity, using Cohen\u27s κ and Gwet\u27s AC statistics. Results: Exact agreement between algorithm scores and reader grades was substantial for both NIH and Miami scales (κ = 0.61 and 0.67, AC = 0.82 and 0.92). Within-one (κ = 0.78 and 0.82) and within-two (κ = 0.80 and 0.84) levels of agreement were almost perfect. The correspondence was comparable to that between readers. Whereas, exact (κ = 0.45 and 0.44, AC = 0.73 and 0.75), within-one (κ = 0.69 and 0.68), and within-two (κ = 0.73 and 0.72) levels of agreement for the two scales were moderate to substantial for acutance calculations. Conclusions: The computer algorithm produces a quantitative measure of vitreous haze that correlates strongly with the perception of expert graders. Translational Relevance: The work offers a rapid, unbiased, standardized means of assessing vitreous haze for clinical and telemedical monitoring of uveitis patients

Validation of a Photographic Vitreous Haze Grading Technique for Clinical Trials in Uveitis

To validate a photographic vitreous haze grading technique using a 9-step logarithmic scale in patients enrolled in a randomized, controlled clinical trial in uveitis. Retrospective study of clinical trials methodology. Setting: University-based department of ophthalmology. Study population: Baseline fundus photographs of patients with intermediate uveitis, posterior uveitis, or panuveitis enrolled in the Multicenter Uveitis Steroid Treatment (MUST) trial. Observational procedure: Grading of vitreous haze using a previously described photographic scale. Regrading of a subset of photographs to assess intraobserver agreement. Main outcome measures: Interobserver and intraobserver intraclass correlation for photographic haze grading, and correlation between photographic and clinical vitreous haze scores, assessment of the clinical findings that significantly affect the photographic haze score. Vitreous haze was graded in 271 eyes (142 patients) by 3 postgraduate ophthalmologists. The interobserver and intraobserver intraclass correlations were excellent, with correlation coefficients between 0.84 and 0.93. There was moderately strong correlation between the photographic and clinical vitreous haze scores ( r = 0.51; P < .001), with significant differences among the mean and median photographic haze scores for the 3 lowest clinical grades of haze, 0, 1+, and 2+. Other parameters that correlated with photographic vitreous haze score included visual acuity of 20/50 or worse ( P = .003), degrees of posterior synechiae ( P < .001), lens abnormality ( P = .023) or posterior capsule obscuration ( P = .001), and amount of anterior vitreous cell ( P = .002). Photographic grading of vitreous haze with a 9-step logarithmic scale is a highly reproducible methodology that may be adaptable to use in future clinical trials

Validation of a Photographic Vitreous Haze Grading Technique for Clinical Trials in Uveitis

PURPOSE: To validate a photographic vitreous haze grading technique using a 9-step logarithmic scale in patients enrolled in a randomized, controlled clinical trial in uveitis. DESIGN: Retrospective study of clinical trials methodology. METHODS: SETTING: University-based department of ophthalmology. STUDY POPULATION: Baseline fundus photographs of patients with intermediate uveitis, posterior uveitis, or panuveitis enrolled in the Multicenter Uveitis Steroid Treatment (MUST) trial. OBSERVATIONAL PROCEDURE: Grading of vitreous haze using a previously described photographic scale. Regrading of a subset of photographs to assess intraobserver agreement. MAIN OUTCOME MEASURES: Interobserver and intraobserver intraclass correlation for photographic haze grading, and correlation between photographic and clinical vitreous haze scores, assessment of the clinical findings that significantly affect the photographic haze score. RESULTS: Vitreous haze was graded in 271 eyes (142 patients) by 3 postgraduate ophthalmologists. The interobserver and intraobserver intraclass correlations were excellent, with correlation coefficients between 0.84 and 0.93. There was moderately strong correlation between the photographic and clinical vitreous haze scores (r = 0.51; P < .001), with significant differences among the mean and median photographic haze scores for the 3 lowest clinical grades of haze, 0, 1+, and 2+. Other parameters that correlated with photographic vitreous haze score included visual acuity of 20/50 or worse (P = .003), degrees of posterior synechiae (P < .001), lens abnormality (P = .023) or posterior capsule obscuration (P = .001), and amount of anterior vitreous cell (P = .002). CONCLUSIONS: Photographic grading of vitreous haze with a 9-step logarithmic scale is a highly reproducible methodology that may be adaptable to use in future clinical trials