A machine vision method for automated alignment of fundus imaging systems.

Background And Objective: To report a method to track the pupil in three axes simultaneously prior to imaging the fundus.

Patients And Methods: The system is based on parallax optical alignment to detect the center of the pupil. The system consists of two cameras acquiring pupil images from two distinct directions and an operator-supervised algorithm to derive the coordinates of the pupil center and output of commands to drive a three-axes computer-controlled stage.

A computer algorithm to quantitatively assess quality of digital optic disc images.

Optic disc photography is used in the management and study of glaucoma. Quality assessment is needed at the time of acquisition and during review. A computerized algorithm for objective quality assessment was developed to mimic the procedure used by human observers.

An image based auto-focusing algorithm for digital fundus photography.

In fundus photography, the task of fine focusing the image is demanding and lack of focus is quite often the cause of suboptimal photographs. The introduction of digital cameras has provided an opportunity to automate the task of focusing. We have developed a software algorithm capable of identifying best focus.

Retinal thickness in eyes of older normal individuals and its implication for the diagnosis of glaucoma.

Purpose: Retinal thickness (RT) is a useful measurement for describing diseases that affect the thickness of the retina, such as glaucoma. Existing normative data are derived from relatively young individuals; however, glaucoma is most prevalent in older individuals. We therefore studied the RT in older normal individuals.

Nature is teaching us to be humble in our quest to measure structure and function in glaucoma.

Relationship between structure and function with regard to glaucoma

Test-retest variability in structural and functional parameters of glaucoma damage in the glaucoma imaging longitudinal study.

Purpose: To determine the test-retest variability in perimetric, optic disc, and macular thickness parameters in a cohort of treated patients with established glaucoma.

Patients And Methods: In this cohort study, the authors analyzed the imaging studies and visual field tests at the baseline and 6-month visits of 162 eyes of 162 participant in the Glaucoma Imaging Longitudinal Study (GILS). They assessed the difference, expressed as the standard error of measurement, of Humphrey field analyzer II (HFA) Swedish Interactive Threshold Algorithm fast, Heidelberg retinal tomograph (HRT) II, and retinal thickness analyzer (RTA) parameters between the two visits and assumed that this difference was due to measurement variability, not pathologic change.

Results of implementation of the DigiScope for diabetic retinopathy assessment in the primary care environment.

Approximately 50% of patients with diabetes in the United States do not undergo recommended ocular evaluations for diabetic retinopathy. The DigiScope (EyeTel Imaging, Inc., Columbia, MD) was developed as a cost-effective and practical telemedicine digital imaging system to screen for diabetic retinopathy in the primary care physician's (PCP) office.

Feasibility of screening for high-risk age-related macular degeneration with an Internet-based automated fundus camera.

Background And Objective: The objective of this pilot study was to determine whether a new screening system, the DigiScope (EyeTel Imaging, Inc., Columbia, MD), can detect the presence of age-related macular degeneration (AMD) at a level requiring referral to an ophthalmologist for further evaluation and possible treatment.

Patients And Methods: The DigiScope is an Internet-based semi-automated digital imaging system designed to be in primary care physicians' offices.

Comparison of a digital retinal imaging system and seven-field stereo color fundus photography to detect diabetic retinopathy in the primary care environment.

Background And Objective: Because patients with diabetes mellitus may visit their primary care physician regularly but not their ophthalmologist, a retinal risk assessment in the primary care setting could improve the screening rate for diabetic retinopathy. An imaging system for use in the primary care setting to identify diabetic retinopathy requiring referral to an ophthalmologist was evaluated.

Patients And Methods: In a masked prospective study, images were obtained from 11 patients with diabetes mellitus using both the digital retinal imaging system and seven-field stereo color fundus photography.

A comparison of quantitative mapping and stereoscopic fundus photography grading of retinal thickness in diabetic eyes with macular edema.

Objective: To evaluate the ability of a retina specialist's grading of 30 degrees color stereoscopic fundus photographs to identify areas of significant retinal thickening as assessed by the Retinal Thickness Analyzer (RTA) and to determine whether this ability was affected by the presence of retinal pathology.

Materials And Methods: Thirty-two eyes in 29 patients clinically diagnosed as having diabetic macular edema underwent RTA scanning and nonsimultaneous 30 degrees color stereoscopic fundus photography. Retinal thickness maps of the macular area were generated, and regions with significant retinal thickening (> or = 2 SD above normal values) were identified.

Comparison between retinal thickness analyzer and optical coherence tomography for assessment of foveal thickness in eyes with macular disease.

Purpose: To use the retinal thickness analyzer (RTA) and optical coherence tomography (OCT) scanners for quantitative measurement of retinal thickness in eyes with macular disease.

Design: In a cross-sectional study, 44 patients (55 eyes) with macular disease and sufficient media clarity to visualize the fundus using clinical biomicroscopy underwent an ophthalmologic examination, fluorescein angiography, RTA, and OCT during the same visit.

Methods: Foveal and foveal center (foveolar) retinal thickness measurements were obtained by RTA and by OCT.

A fundus camera dedicated to the screening of diabetic retinopathy in the primary-care physician's office.

Purpose: To increase the number of diabetic patients being screened for retinopathy, an instrument, the DigiScope, was specifically designed to operate in primary-care physicians' offices. The DigiScope is described and its automated functions are evaluated.

Methods: The DigiScope consists of a semiautomated optical head to acquire fundus images, evaluate visual acuity, and transmit the data to a remote reading center through telephone lines.

Relation between retinal thickening and clinically visible fundus pathologies in mild nonproliferative diabetic retinopathy.

Background And Objective: To determine the association of retinal thickening (RT) with clinically observable retinal pathologies in eyes with mild nonproliferative diabetic retinopathy.

Patients And Methods: Using an objective quantitative imaging method (Retinal Thickness Analyzer), the ratio relative to normal RT (RTI) was measured in 23 eyes with and 35 eyes without clinically observable diabetic fundus pathology. RTI was analyzed in relation to presence of mild diabetic retinal lesions in the +/-0.

Laser targeted photo-occlusion of rat choroidal neovascularization without collateral damage.

Laser targeted photo-occlusion (LTO) is a novel method being developed to treat choroidal neovascular membranes (CNV) in age-related and other macular degenerations. A photosensitive agent, encapsulated in heat-sensitive liposomes, is administered intravenously. A low power laser warms the targeted tissue and releases a bolus of photosensitizer.

Redefining papillorenal syndrome: an underdiagnosed cause of ocular and renal morbidity.

Purpose: To report ocular and renal findings specific to the inheritable entity called papillorenal (also known as renal-coloboma) syndrome and relate these to a common cause.

Design: Observational case series and genetic study.

Participants: Two unrelated probands presenting with absent central retinal vessels and 11 available family members.

Large diurnal fluctuations in intraocular pressure are an independent risk factor in patients with glaucoma.

Purpose: To study the risk associated with diurnal intraocular pressure (IOP) variations in patients with open-angle glaucoma.

Patients And Methods: Sixty-four patients (105 eyes) from the practices of two glaucoma specialists successfully performed home tonometry with a self-tonometer five times a day for 5 days. All patients had open-angle glaucoma and documented IOP below 25 mm Hg over a mean follow-up period of 5 years.

Noninvasive mapping of the normal retinal thickness at the posterior pole.

Objective: Objective and sensitive measurements of the retinal thickness at the posterior pole are useful to detect and delineate macular edema or retinal atrophy. The authors therefore developed an instrument, the Retinal Thickness Analyzer (RTA), to map the retinal thickness rapidly. The RTA was used to study the normal thickness at the posterior pole and to provide a pilot baseline.

A new method for noninvasive optical sectioning of the chorioretinal vasculature.

Purpose: To report a new method for optical sectioning of the chorioretinal vasculature to improve the visualization of vascular abnormalities due to chorioretinal eye diseases.

Methods: An imaging system was developed for optical sectioning of the vasculature called chorioretinal optical sectioning (CROS). CROS consists of projecting a laser beam at an angle on the retina after injection of a fluorescent dye and viewing the fluorescence.

Optical cross-sectional imaging of the macula with the retinal thickness analyzer in X-linked retinoschisis.

Objective: To assess the morphologic characteristics of the foveal abnormality in juvenile X-linked retinoschisis using the scanning retinal thickness analyzer (RTA). This characteristic foveal abnormality is present in 83% to 100% of patients with X-linked retinoschisis and has not been demonstrated histopathologically.

Methods: The RTA is a noncontact imaging device.

Quantitative detection of glaucomatous damage at the posterior pole by retinal thickness mapping. A pilot study.

Objective: The posterior pole ganglion cell bodies form a substantial fraction of the retinal thickness, prompting the authors to study the feasibility of detecting, by scanning retinal thickness analysis, retinal changes at the posterior pole due to glaucomatous damage.

Study Design: Nonconsecutive case series.

Participants: One or both eyes of patients with chronic open-angle glaucoma who presented with either a superoinferior asymmetry in visual fields or a localized field loss or a nerve fiber layer defect visible on photography were recruited.

Serial optical sectioning of macular holes at different stages of development.

Objective: This study aimed to examine the characteristics of intraretinal changes associated with macular holes and epiretinal membranes by scanning retinal thickness analysis.

Study Design: The study design was a nonconsecutive case series.

Patients: Fifty-six eyes of patients who had either a suspected or clinically diagnosed macular hole or epiretinal membrane were recruited.