Biomedical subjects

J Yoken

Publications and source records attributed to J Yoken.

3 recordsLinked to original sources

PubMed2000

Computer-assisted quantitation of choroidal neovascularization for clinical trials.

PURPOSE: To develop a computer-assisted method for the quantitation of choroidal neovascularization (CNV) for the support of clinical trials. METHODS: Fluorescein angiographic images were selected from 5 patients enrolled in a clinical trial for which three follow-up visits were available. Thirty- and 600-second images were digitized at 1000 dots/in and registered (aligned) with polynomial warping algorithms. Custom-developed software allowed for coarse, automated identification of CNV. An easy-to-use graphical user interface facilitated supervision and refinement of the lesion boundaries by a skilled reader based on standard stereoscopic viewing of the fluorescein angiography study. Capabilities for boundary delineation in both early and late phases, and animation to allow for image correlation and evaluation of temporal changes in fluorescence of spatially corresponding pixels, were included. Two metrics for CNV characterization were generated. First, the lesion area based on the lesion boundaries was identified after supervision. Second, an integrated lesion intensity (ILI) reflecting the integrated, normalized lesion hyperfluorescence was calculated. RESULTS: Area and ILI measures were calculated for each of 5 patients for three or more visits. Facile supervision based on the stereoscopic angiogram permitted arbitrarily close concordance with CNV identification using standard methods. Changes in area and ILI measurements between visits correlated closely with clinically observed changes in each case. CONCLUSIONS: Interactive image processing permits efficient, accurate, computer-assisted CNV quantitation that may be useful for the support of clinical trials and preclinical studies.

Choroid↗

PubMed1999

Laser-induced drusen reduction improves visual function at 1 year. Choroidal Neovascularization Prevention Trial Research Group.

OBJECTIVE: To describe the relationship of laser-induced drusen reduction to change in visual function at 1 year among patients enrolled in the Choroidal Neovascularization Prevention Trial (CNVPT). DESIGN: Comparison of groups with and without drusen reduction; follow-up of a randomized controlled trial. PARTICIPANTS: Evaluations of drusen and visual acuity at baseline and at 1 year were performed for 351 eyes of the 432 eyes enrolled in the CNVPT Bilateral Drusen Study and Fellow Eye Study (81%). One hundred eighty-four eyes were assigned to observation, and 167 eyes were assigned to laser treatment. Eyes with conditions that precluded an analysis of drusen reduction, such as those that developed choroidal neovascularization (CNV) within the first year, are excluded from this analysis. METHODS: Change in macular drusen between initial visit and after 1 year was assessed by side-by-side grading by evaluators masked to information on visual function. Visual acuity, contrast threshold, and critical print size were measured by certified visual function examiners. MAIN OUTCOME MEASURES: Change in visual acuity is the primary outcome. Change in contrast threshold and change in critical print size are secondary outcome measures. RESULTS: Laser-treated eyes with 50% or more drusen reduction at 1 year had more 1- and 2-line increases in visual acuity and less losses in visual acuity compared with laser-treated eyes with less drusen reduction or with observed eyes (P = 0.001). Similar improvements were noted for contrast threshold but not critical print size at 1 year. CONCLUSIONS: Laser-induced drusen reduction is associated with improved visual acuity and contrast sensitivity in eyes at 1 year. Longer term effects of laser-induced drusen reduction on visual function require additional observation. The overall potential value of laser treatment in eyes with high-risk drusen requires consideration of not only short-term effects on vision but also the effects of CNV and atrophy on vision.

Aged↗

PubMed1999

A false-positive Seidel test after Ahmed valve insertion.

An 80-year-old monocular man with long-standing primary open angle glaucoma underwent successful filtering surgery in his sighted right eye in 1980. He subsequently developed a cataract and had an uncomplicated clear cornea phacoemulsification with posterior chamber intraocular lens in 1996. Post-operatively, the filtration bleb remained very avascular but shallowed; the intraocular pressure increased and remained uncontrolled despite maximally tolerated medical therapy. His vision improved to 6/7.5 and automated perimetry revealed a less than 5 degrees small central island of vision. His left eye was phthisical with no light perception.

Aged↗