. A treatise on diseases of the eye . dation; if he is hyperopic or myopic, a suitable lens must be rotatedbehind the sighthole in the ()j)hthalmoscoj)e to correct the error. The color of the reflex varies with the size of the j)U{)il, (he error ofrefraction, the transparency of the media, and the degree of pigmcniation 132 EXAMINATION of the iiRnibniiKs of the eye. With the mirror at the distance iiuHcated,the reflex from all parts of the fundus is examined for the detection ofopacities in the media. These usually appear black. If a blood clot,the reflex is red; if an exudate, gray or yellow.
. A treatise on diseases of the eye . dation; if he is hyperopic or myopic, a suitable lens must be rotatedbehind the sighthole in the ()j)hthalmoscoj)e to correct the error. The color of the reflex varies with the size of the j)U{)il, (he error ofrefraction, the transparency of the media, and the degree of pigmcniation 132 EXAMINATION of the iiRnibniiKs of the eye. With the mirror at the distance iiuHcated,the reflex from all parts of the fundus is examined for the detection ofopacities in the media. These usually appear black. If a blood clot,the reflex is red; if an exudate, gray or yellow. Detachment of theretina gives an luieven pearly gray reflex. Intra-ocular parasites or neo-plasms give reflexes of various kinds. The reflex may be disturbed byirregularities in cornea or lens without opacification. Tlie patients eye is now apj)roached to within 2 or 3 cm., the patientshead l)eing steadied by the free hand of the observer if necessary, andthe optic disk sought for. From this oi)jective point all parts of the Fig. 96. The direct method of ophthahnoscopic exiimination. (Posey and Wright.) fundus should be carefully examined. The foregoing has been writtenunder the supposition that the pcdieiifs eye is emmetropic. In case heis hyperoj)ic, or myopic in moderate degree, the observer may rotatesuitable correcting lenses behind the sight-hole of the ophthalmoscopebefore proceeding with the examination. In high degrees of myopia,with or without astigmatism, it is often best to permit the patient to wearhis own correcting lenses. P^xamination of the highly myopic eye bythe direct method is ditficult and not infrequently unsatisfactory. This method is employed for determining the refraction of the eye(see P>rors of Refraction and their Correction) and for determining theelevation of neoplasms, swollen nerve head, masses of exudation, new- PLATE X FIG. 1
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