1216 AMERICAN JOURNAL

perimetry in the assessment of optic nerve conduc­tion defects. Tr. Ophth. Soc. U.K. 89:67, 1969.

R E P L Y

Editor, American Journal of Ophthalmology :

Thank you for letting me see the letter from Drs. Ellenberger and Bürde. I think it is important for research techniques to be applied to examination of the visual fields and should like to encourage them to con­tinue this. However, in personally perform­ing quantitative perimetry on nearly every new patient seen in my office for over 15 years, I have come to the conclusion that ex­amination of the visual fields is one of the most poorly taught subjects in ophthalmol­ogy. There is no question that it is not the instrumentation but the examiner that is critical in subjective testing. Although the Goldmann perimeter enjoys great popularity today, we must remember that the truth is not defined by majority vote. The Goldmann primeter possesses certain limitations in the assessment of neuro-ophthalmologic patients which caused me to abandon its use after several months of trial. One has great diffi­culty with a patient with a dropping eyelid, narrow fissures, or a prominent brow with the Goldmann perimeter. The only way that the eyelids can be elevated is by taping them up (uncomfortable for the patient and causes drying of the cornea) or having an assistant elevate the eyelids (and this is not synchronized nicely with the examiner's studies). The greatest defect, however, is that one cannot perform color field isopters with this instrument, and the 3/330 red and 5/330 red isopters are often critical in de­tecting temporal lobe and chiasmal lesions in my experience. The Ednalite projection light technique as taught by Dr. Cogan has proved, in my experience, to be the simplest, quickest, and best way to obtain precise fixa­tion on the tangent screen studies. The Ai-mark perimeter has been the most reliable instrument for peripheral studies in my hands. It is of interest that E. W. D. Norton

OF OPHTHALMOLOGY DECEMBER, 1972

uses a large, one-meter perimeter with a sim­ple projector light technique, and although he thus uses quite different instrumentation, we both are constantly surprised at the simi­larity of our visual field findings and inter­pretations.

This letter is a plea for careful teaching of visual field techniques to ophthalmologists. One often finds significant field defects missed by second-year ophthalmology resi­dents rotating on a neuro-ophthalmology ser­vice, and if physicians miss such defects, one must be concerned for the findings of techni­cians with no medical training whatever. There is no question that one must maintain the same illumination in the examining room for fields done in that room by the same ex­aminer to be reproducible. However, it may be reassuring to the practicing ophthalmolo­gist to recall that new clinical information was obtained (i.e., cecocentral scotomas have been found with optic nerve hypoplasia) from studying visual fields with an $11 in­strument that can be carried in one's pocket on ward rounds.

J. Lawton Smith, M.D. 1638 N.W. 10th Avenue

Miami, Florida 33136

OCULAR CIRCULATION IN HYPERTENSION

Editor, American Journal of Ophthalmology :

I was very much interested in a recent pa­per by Drs. Archer, Ernest, and Krill (Reti­nal, choroidal, and papillary circulations un­der conditions of finduced ocular hyperten­sion. Am. J. Ophth. 73:834, 1972). I have a particular interest in this subject, having also investigated it,1-6 and I cannot agree with the interpretation by Archer and his associates of the choroidal filling shown in the illustra­tions of their article. My experience of cho­roidal filling defects observed in raised intra­ocular pressure, both in experiments with rhesus monkeys and in patients with glau­coma, leads me to a totally different interpre­tation. Archer and associates stated that "the

VOL. 74, NO. 6 CORRESPONDENCE 1217

retinal and choroidal vasculatures were found to fill at the same level of intraocular pressure." My own and other investigators' observations indicate that this is not so. Sim­ilarly, in all the pictures presented by Archer and associates I find the choroidal filling by fluorescein to be significantly less than the retinal filling. For example, in Figures 2 and 5, apart from a small sectorial and patchy filling of some of the choroidal vessels, al­most the whole of the rest of the choroid has not filled, whereas all the retinal arterioles have filled completely. In Figures 3 and 4, photographed at pressures up to 61 mm Hg, only a small area of choroid shows a patchy filling in the superotemporal region while all the retinal arterioles are completely filled ; even in Figure 4-C the entire nasal half of the choroid has not filled. None of the pic­tures show any filling of the posterior ciliary arterial contribution to the optic disk which is not at all difficult to detect when the prela-minar vessels have filled adequately.

Since the posterior choroid is supplied by 10-20 short posterior ciliary arteries, the fill­ing of an odd big choroidal vessel in the dis­tribution of one or two short posterior cili­ary arteries synchronous with the retinal ar-teriolar filling (as seen in the illustrations of Archer and associates) does not alter the fact that the major part of the choroidal cir­culation remained completely empty, whereas the entire retinal arteriolar tree has filled completely. Furthermore, for the nutri­tion and survival of the optic nerve head (which is almost entirely supplied by the posterior ciliary arteries), the vessels that matter are the ones supplying the nerve ; the filling of an odd big choroidal artery in one sector is immaterial. The fact that the occa­sional big choroidal vessel fills simultane­ously with the retinal vessels has no impor­tance whatsoever when considered in rela­tion to the interference with blood supply of the optic disk in raised intraocular pressure, and consequently, to the optic disk and visual field changes in glaucoma.

In a word, the conclusions reached by

Archer and associates are based on a misin­terpretation of their pictures, and are of lit­tle practical significance in the consideration of optic disk changes and field defects in glaucoma.

Sohan Singh Hayreh, M.S., Ph.D., F.R.C.S.

Department of Ophthalmology University of Edinburgh

Edinburgh, EH3 9HA, Scotland

REFERENCES

1. Hayreh, S. S., and Perkins, E. S.: Clinical and experimental studies on the circulation at the optic nerve head. Proc. William Mackenzie Centeneray Symposium on the Ocular Circulation in Health and disease. London, Kimpton, 1968, p. 71.

2. : The effects of raised intraocular pres­sure on the blood vessels of the retina and optic disk. Proc. Int. Symp. Fluorescein Angiography, Albi. Basel, Karger, 1969, p. 323.

3. Hayreh, S. S. : Blood supply of the optic nerve head and its role in optic atrophy, glaucoma, and oedema of the optic disk. Proc. Int. Symp. Fluorescein Angiography, Albi. Basel, Karger, 1969, p. 510.

4. : Blood supply of the optic nerve head and its role in optic atrophy, glaucoma and oedema of the optic disk. Brit. J. Ophth. 53:721, 1969.

5. Hayreh, S. S., Revie, I. H. S., and Edwards, J.: Vasogenic origin of visual field defects and optic nerve changes in glaucoma. Brit. J. Ophth. 54:461, 1970.

6. Hayreh, S. S.. : Optic disk changes in glau­coma. Brit. J. Ophth. 56:175, 1972.

REPLY

Editor, American Journal of Ophthalmology:

In our paper, "Retinal, choroidal, and pa­pillary circulations under conditions of in­duced ocular hypertension" (Am. J. Ophth. 73:834, 1972), we did not discuss the role of the choroid in optic disk and field defects in glaucoma. We agree with Hayreh that the peripapillary choroid and choriocapillaris is of no importance for the blood supply of the optic disk and are preparing a paper in which we demonstrate that the disk circula­tion is independent of the choroid.

We have heard Hayreh speak on his mon­key work and we are interested to learn he has studied glaucomatous patients. Our