The student's guide to diseases of the eye . take is excusableonly when there is diffused mistiness of the vitreousfrom opacities which are too small to be easilydistinguished (Chap. XVI), and the difficulty isthen increased because this very condition of thevitreous often coexists with retinitis. A comparisonof the erect and inverted images is often useful; forif the diffused haze noticed by indirect examinationbe caused by retinitis, then by the direct examinationwhat before seemed a uniform haze may now appearas well-marked spotting or streaking. When the DISEASES OP THE RETINA 185 change i
The student's guide to diseases of the eye . take is excusableonly when there is diffused mistiness of the vitreousfrom opacities which are too small to be easilydistinguished (Chap. XVI), and the difficulty isthen increased because this very condition of thevitreous often coexists with retinitis. A comparisonof the erect and inverted images is often useful; forif the diffused haze noticed by indirect examinationbe caused by retinitis, then by the direct examinationwhat before seemed a uniform haze may now appearas well-marked spotting or streaking. When the DISEASES OP THE RETINA 185 change is pronounced enough to cause a decidedlywhite haze of the retina there is no longer anydoubt. The retinal arteries and veins are sometimesenlarged and tortuous in retinitis, and in severecases they are generally obscured in some part oftheir course. These forms of uniformly diffusedretinitis are usually caused either by syphilis orembolism. (2.) Near the y. s. a number of small, intenselywhite, rounded spots are seen (Fig. 73), either quite. Fig. 73.—Renal retinitis at a late stage (Wecker and Jaeger). discrete or partly confluent. When very abundantand confluent they form large, abruptly outlinedpatches, with irregular borders, some parts of thesepatches being striated, others stippled. (3.) A number of separate patches are scatteredabout the central region, but without special referenceto the y. s. They are of irregular shape, white orpale buff, and sometimes striated (Fig. 74) ; theyare easily distinguished from patches of choroidal-atrophy (p. 168) by their colour, the comparative 186 DISEASES OF THE RETINA softness of their outlines, and the absence ofpigmentation. In types 2 and 3, some haemorrhages are usuallypresent; the retina generally may be clear, but moreoften there is diffused haze and evidence of haemorrhages may be so numerous and large as
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