| ocular muscles | The voluntary muscles which control eye movement (27 Sep 1997) |
|---|---|
| medial nasal primordium | An ectodermally covered mesenchymal swelling lying medial to the olfactory placode or pit in the embryo. Synonym: medial nasal fold, medial nasal primordium, medial nasal process. (05 Mar 2000) |
| primordium | An aggregation of cells in the embryo indicating the first trace of an organ or structure. Synonym: anlage. Origin: L. Origin, fr. Primus, first, + ordior, to begin (05 Mar 2000) |
| lateral nasal primordium | An ectodermally covered mesenchymal swelling separating the embryonic olfactory pit from the developing eye. Synonym: lateral nasal fold, lateral nasal primordium, lateral nasal process. (05 Mar 2000) |
| frontonasal primordium | The unpaired embryonic prominence between the medial nasal elevations, which eventually merges with them to contribute to the bridge of the nose and the underlying nasal septum. Synonym: forebrain eminence, forebrain prominence, frontonasal primordium, frontonasal process. (05 Mar 2000) |
| accommodation, ocular | The dioptric adjustment of the eye (to attain maximal sharpness of retinal imagery for an object of regard) referring to the ability, to the mechanism, or to the process. It is the effecting of refractive changes by changes in the shape of the crystalline lens. Loosely, it refers to ocular adjustments for vision at various distances. (12 Dec 1998) |
| adaptation, ocular | The adjustment of the eye to variations in the intensity of light. Light adaptation is the adjustment of the eye when the light threshold is increased; dark adaptation when the light is greatly reduced. (12 Dec 1998) |
| albinism, ocular | Albinism affecting the eye in which pigment of the hair and skin is normal or only slightly diluted. The classic type is x-linked (nettleship-falls), but an autosomal recessive form also exists. Ocular abnormalities may include reduced pigmentation of the iris, nystagmus, photophobia, strabismus, and decreased visual acuity. (12 Dec 1998) |
| anterior ocular segment | That portion of the eye comprising the cornea, iris, lens, and their associated chambers and adnexa. (05 Mar 2000) |
| cardinal ocular movements | Eye rotations to the right and left, upward to the right and left, and downward to the right and left, to diagnose positions of gaze. (05 Mar 2000) |
| Ramsden's ocular | An eyepiece of a microscope, consisting of two planoconvex lenses with convexities turned to each other. (05 Mar 2000) |
| vestibular ocular reflex | <clinical sign> Reflex movement of the eyes in the opposite direction to that which the head is moved, e.g., the eyes being lowered as the head is raised, and the reverse (Cantelli's sign); an indication of functional integrity of the brainstem tegmental pathways and cranial nerves involved in eye movement. Synonym: vestibular ocular reflex. (05 Mar 2000) |
| reflex, vestibulo-ocular | A reflex wherein impulses are conveyed from the cupulas of the saemicircular canals and from the otolithic membrane of the saccule and utricle via the vestibular nuclei of the brainstem and the median longitudinal fasciculus to the oculomotor nerve nuclei. It functions to maintain a stable retinal image during head rotation by generating appropriate compensatory eye movements. (12 Dec 1998) |
| refraction, ocular | Refraction of light effected by the media of the eye. It also includes the determination of the refractive state and refractive correction. (12 Dec 1998) |
| goniometre ocular | <microscopy> A special type of ocular fitted with crosslines and a graduated head which rotates the crosslines to facilitate the measuring of angles, as in crystallography. (05 Aug 1998) |