The name photorefraction (PR) refers to the refraction measurement made from PS images. A less ambiguous means of evaluating a PS device is to determine the accuracy in detecting individual vision abnormalities separately. The result is therefore strongly influenced by the selected cohort and the pass-fail criteria defined for each abnormality. The evaluation of PS devices in vision screening typically uses pass-fail criteria. In addition to the ease of use, PS is capable of simultaneously detecting multiple amblyogenic conditions including strabismus, optical media opacities, and binocular refractive errors. It does not require careful positioning of the eyes or patient cooperation. A PS measurement involves taking photographs of the eyes at a distance, typically one meter. Photoscreening (PS) has been a popular objective method for pediatric vision screening because of its simplicity of use 1. This suggests that enhancements in the PR system and analysis may satisfactorily correct intersubject variability that currently limits the clinical use of PR devices and measurements. Age, race, and pupil size did not appear to significantly affect DOES PR measurement. Inaccuracy increased at high refraction (>4D). In the region between -4 diopter (D) and +4D, the device showed a binocular refraction measurement accuracy of 0.45 D, 0.3 D, and 0.18 D root-mean-square (RMS) error (n=1337) for spherical equivalent and cross cylinders J o and J 45, respectively. The influence of intraocular scattering, retinal reflectance, and pupil size was evaluated by comparing results from different age groups, races, and lighting conditions. The correlation and standard deviation were determined by Bland-Altman analysis. These results were compared to the standard clinical refraction testing performed the same day. We performed DOES measurements in 99 volunteers (198 eyes) under two environmental light conditions and using four fixation targets. The objective of our studies was to clinically evaluate the accuracy of refraction measurements of an improved PR-based device, the Dynamic Ocular Evaluation System (DOES), and to investigate whether the accuracy is affected by the patient’s age, race, and pupil size, which are relevant to individual intraocular scattering and retinal reflectance. While PR is easy to implement, the accuracy of refractive error measurements in humans has been unsatisfactory, largely due to the variations of intraocular scattering, the retinal reflectance, and pupil size. read more ).Photorefraction (PR) methods have beenwidely used for pediatric vision screening since the 1980’s. Symptoms and signs include diplopia, ptosis, and paresis of eye adduction and of upward and downward gaze. read more or 3rd cranial nerve palsy Third Cranial (Oculomotor) Nerve Disorders Third cranial nerve disorders can impair ocular motility, pupillary function, or both. (See also Overview of the Autonomic Nervous System.) Horner syndrome results when the cervical. read more ) and headaches or other neurologic symptoms ( Horner syndrome Horner Syndrome Horner syndrome is ptosis, miosis, and anhidrosis due to dysfunction of cervical sympathetic output. Review of systems seeks symptoms that may suggest a cause, such as birth defects or chromosomal abnormalities (congenital defects) droopy eyelid, cough, chest pain, or dyspnea (Horner syndrome) genital lesions, adenopathy, rashes, or fever ( syphilis Syphilis Syphilis is caused by the spirochete Treponema pallidum and is characterized by 3 sequential symptomatic stages separated by periods of asymptomatic latent infection. Symptoms of acute angle closure are severe ocular pain. read more, acute angle-closure glaucoma Angle-Closure Glaucoma Angle-closure glaucoma is glaucoma associated with a physically obstructed anterior chamber angle, which may be chronic or, rarely, acute. Symptoms include sudden, severe headache, usually. The most common cause of spontaneous bleeding is a ruptured aneurysm. read more, subarachnoid hemorrhage Subarachnoid Hemorrhage (SAH) Subarachnoid hemorrhage is sudden bleeding into the subarachnoid space. read more, stroke Ischemic Stroke Ischemic stroke is sudden neurologic deficits that result from focal cerebral ischemia associated with permanent brain infarction (eg, positive results on diffusion-weighted MRI). However, the retina and fluid within the anterior chamber and vitreous are often involved as well. Many disorders are accompanied by anisocoria due to iris or neurologic dysfunction but usually manifest with other, more bothersome symptoms (eg, uveitis Overview of Uveitis Uveitis is defined as inflammation of the uveal tract-the iris, ciliary body, and choroid.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |