The exposed position of the eye lends itself readily to external inspection. The biomicroscope allows of a detailed examination under 15 to 30 magnifications of the conjunctiva, cornea, anterior chamber, iris. lens, vitreous, and portions of the retina. Gonioscopy provides a direct view of the filtration angle and the base of the iris while improved methods of indirect ophthalmoscopy bring into view the entire retina out to the oraserrata and beyond. Thus there is little of the eye that does not lend itself to observation. Perimetry and campimetry provide an indirect means of evaluating the integrity of the visual pathway from the eyeball to the occipital cortex.

Examination of the eyes is richly rewarding to the diligent observer. No other organ in the body mirrors evidence of so many variegated remote diseases, intracranial and systemic. Complete evaluation of the eyes includes a survey of 50 percent of the cranial nerve in whole or in part, and ophthalmoscopy affords the only opportunity tor direct visualization of blood vessels.

Visual acuity should always be estimated. preferable with the Snellen chart. When vision is less than 20/200, the distance at which fingers can be counted is measured. lf fingers cannot be counted. the ability of the patient to recognize the direction of hand movement is determined. Below this ievel vision is recorded as light projection when the patient can appreciate the direction from which a light is coming, or light perception only, when he can tell when a light is on or oft'. This degree of impairment of vision is a short step from total blindness.

In examining the fundus, the characteristic of the optic disc to be noted are the cotor, cupping and outline. The normal disc exhibits a pinkish color with a pale central depressed area, the physiologic cupping. The remainder of the fundus generally appears bright orange-red in color with the retinal vessels coursing over it from the disc. Variations trom the normal are noted such as pallor of the disc or blurring of the margins with distention of the veins or increased cupping of the disc extending to its margins. In the retina. hemorrhages. white spots of exudate, pigmentary disturbances or other variations from the normal are noted.

Opacities of the cornea, lens, or vitreous are seen as light to dark grayish or black spots against the background of the orange-red fundus reflex, and the location of an opacity, whether in the cornea or lens, is determined by parallax. With the patient's eye held steady and maintaining the beam of light through the pupil the examiner moves the ophthalmoscope up and down or sideways. If the opacity appears to move in the opposite direction. it is in the cornea. No motion of the opacity places it in the anterior layers of the lens while apparent movement in the same direction locates it in the middle or posterior layers of the lens. The distinctive feature of vitreous opacities is their actual movement on motion of the eye. Thus. if the patient moves his eye up and down and then holds it steady, opacities in the vitreous will be seen to swirl about', since they are present in a semifluid medium, whereas opacities in the cornea or lens are fixed and occupy the same position in the pupillary reflex as before the eye moved.

An estimate of intraocular pressure can be obtained by palpation of the globe through the lids. The tonometer provides a simple and more reliable pressure of the intraocular pressure. The visual fields can be roughly estimated by confrontationbut the perimeter and tangent screen yields more accurate informatíon. The color of the macular area and presence of a foveal reflex are noted. The retina is examined for scars. detachments, tumor, or pigmentary disturbances.

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