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Biomedical subjects

H Uozato

Publications and source records attributed to H Uozato.

6 recordsLinked to original sources

Rapid determination of intraocular lens tilt and decentration through the undilated pupil.

The apparent optical axis of an implanted intraocular lens (IOL) can be located by alignment of the examiner's hand light with the third and fourth Purkinje images from the front and back surfaces of the IOL. Tilt of the IOL can be estimated (or measured with an arc perimeter) by the angle between the apparent optical axis and the patient's line of sight (actual tilt approximately 0.85 x apparent tilt). Decentration of the IOL is easily detected, equal to the distance of the IOL optical axis from the center of the pupil. This simple technique can be used through the natural pupil with posterior chamber IOLs, providing the optical axis of the malpositioned IOL still passes through the pupil.

Humans

Centering corneal surgical procedures.

Currently used methods for centering corneal surgical procedures emphasize the visual axis of the eye but do not define it properly. We obtained the best optical result by centering the surgical procedure on the line of sight and entrance pupil of the eye, not on the visual axis. We found an error of 0.5 to 0.8 mm in currently used methods of marking the visual axis, which arose from the use of the corneal light reflex as a sighting point or from inadvertent monocular sighting in techniques requiring binocular sighting. Proper centering requires the patient to fixate on a point that is coaxial with the surgeon's sighting eye, and the cornea is marked at the point in line with the center of the patient's entrance pupil, ignoring the corneal light reflex.

Cornea

Depth distortion during slitlamp biomicroscopy of the fundus.

The apparent depth of an optic nerve cup or apparent height of a fundus lesion changes with the optics used by an examiner. With slit-lamp biomicroscopy of the fundus, both the auxiliary fundus lens and the biomicroscope contribute to differences in magnification that produces distortion of the object. It is important to understand these differences so that inaccurate conclusions are not drawn and inappropriate therapy will not be instituted when the examiner uses different instruments for making serial observations or uses an unfamiliar instrument.

Depth Perception

Visual-evoked potentials elicited by laser speckle patterns. Studies on the characteristics and assessment of visual function in patients with ocular media opacities.

Visual-evoked potentials (VEPs) were recorded using a laser speckle pattern. Stimulation with a speckle pattern was elicited either by pattern appearance-disappearance or by pattern shift. The VEPs obtained by this method were similar in properties to the previous pattern VEPs that were obtained either by pattern appearance-disappearance or by pattern reversal. Patients in whom dense and diffuse ocular media opacity defied measurement by the interferometric visual acuity method were studied to test if the speckle pattern generated by diffusion from lens opacity itself could act as a stimulus for obtaining VEPs. It is concluded that the present method enables one to obtain a reliable VEP and to assess the visual function of the retino-cortical system, even in patients with mature cataracts.

Adult