462 AMERICAN JOURNAL OF OPHTHALMOLOGY MARCH, 1968

tional understanding. How much more ef­fective than some of our foreign-aid give­away programs!

Beginning April 15, 1968, the ship will be at Colombo, Ceylon. The ophthalmic needs of this country are unlimited. Colombo boasts a 750-bed eye hospital and serves 1,000 out-patients a day. There are three ophthalmologists, together with a resident staff. Dozens of cataracts are performed daily in short periods of time. The needs of the opthalmology staff for Project H O P E in Ceylon lie in the direction of teaching retinal detachment and plastic surgery, which are not being performed now. The Ceylon eye staff certainly does not need to be shown cat­aract procedures taking up to an hour!

May I urge ophthalmologists to volunteer to serve with HOPE in Ceylon ? You will be fascinated by seeing new cultures and mak­ing new friends, and stimulated by ophthalmic problems found mostly in text­books. You will be rewarded in the satisfac­tion that you have contributed knowledge to a developing nation and demonstrated and democratic process in action. Your evenings and week-ends will often be spent with the families of local physicians, educators and government officials. How interesting this is in comparison to visiting a foreign country and mixing only with other American tour­ists!

Those of us who have had the opportunity to serve aboard the HOPE return to our practices refreshed and with the awareness that our own problems are not as monumen­tal as we previously thought. The fact that most of the serving doctors return for other trips speaks of the satisfaction each has ex­perienced.

Specialists will rotate to Ceylon by air be­ginning April 15 for two-month periods. There will be three ophthalmologists aboard the S.S. H O P E in each rotation. All travel and living expenses are provided by Project HOPE. Those who wish to apply please write to Project HOPE, 2233 Wisconsin Avenue, N.W., Washington D.C. 20007.

Davis G. Durham

REFERENCES

1. Walsh, W. B.: A Ship Called HOPE. Reader's Digest Condensed Books, Winter, Vol. 1,1965.

2. Walsh, W. B.: Yanqui, Come Back! New York, Dutton, 1966.

3. Durham, D. G.: Ophthalmology and Project HOPE. Am. J. Ophth. 55:748, 1963.

CORRESPONDENCE APHAKIC CORRECTION

Editor, American Journal of Ophthalmology:

It has come to my attention that many very elderly binocular aphakic patients who are wearing bifocal aphakic spectacle lenses can be helped considerably by single vision aphakic spectacle lenses for walking about.

As has been recently pointed out by Dr. Arthur Linksz, if the single vision aphakic glasses are adjusted closely to the eyes and if the prescription is correct at this close ad­justment, sufficient dioptric power can be gained for "in the store reading," etc by slipping the glasses down on the nose as far as possible.

In single vision lenses for aphakia, as-pherics are slightly to somewhat better than nonaspherics but not "miraculously better" in the experience of my patients who have been given two identical sets of well de­signed aspheric and nonaspheric spectacles to compare.

It should be pointed out that at the present time none of the plastic aspheric spectacle lenses for aphakia are aspheric in the area of the bifocal segment.

Robert C. Welsh Miami, Florida

SIMPLIFIED EXTERNAL EYE PHOTOGRAPHY

Editor, American Journal of Ophthalmology:

The article by Dr. Arthur Sherman (Am. J. Ophth. 64: 1159, 1967) regarding simpli­fied office photography was of great interest.

To my own satisfaction, I use one of the

VOL. 65, NO. 3 CORRESPONDENCE 463

newer Polaroid Electric Eye cameras. I have a lens adaptor with a +11.75 lens mounted. At an approximate four-inch working dis­tance, and with the Polaroid set for infinity and the exposure set for black and white, using color film I am able to get excellent color prints. The price of my Polaroid is $39. I use an inexpensive Strobe flash ($18).

The advantages are that both the patient and I are able to see the pictures in one min­ute and I know the exposure and angle ex­posed a good picture.

I do not have to wait weeks or months until the roll of 35 mm film is finished. I do not have to use a viewer. I have a large print with approximately one and one-half to two times enlargement immediately available. Copies are readily and inexpensively avail­able also.

Joel V. Levy Anaheim, California

EFFECT OF OCULAR INSTILLATION OF ECHO-THIOPHATE IODIDE AND ISOFLUROPHATE

ON CHOLINESTERASE ACTIVITY OF VARIOUS RABBIT TISSUES

Editor, American Journal of Ophthalmology:

I should like to correct two errors of in­terpretation reported in the paper by Dr. Anthony de Roetth's group (Am. J. Ophth. 64:398,1967).

I assayed brain cortex only in rabbits, being fully cognizant of the variation in cho-linesterase content in different parts of the brain of various species. This paper reports "that with 0.5% solution of echothiophate once daily, enzyme (cholinesterase) was in­hibited 40% in brain cortex and medulla." In my experiments, I found inhibition to 29.8%. At lower dose levels of echothio­phate, less inhibition occurred. I gave 0.25% solution of this drug twice daily, so that es­sentially the same dose was used. I reported that on the basis of this finding of inhibition that the permeability of the blood-brain bar­

rier to this drug is not complete, but only relative, and in my findings occurred after a period of about 48 hours. It seems that this new report is no different. Assays of homog-enates, essentially a soup, by two different methods readily vary this degree, but the conclusions drawn in this case are similar.

My report on "paradoxical" elevation of intraocular pressure in rabbits appeared only in a 50-word abstract, so that only a bare content was possible. I found that increased intraocular pressure occurred in many rab­bits about three days after twice-daily instil­lation of 0.25% echothiophate and other drugs of this group, to levels as high as 45 mm Hg, at a time when the pupil was no longer miotic as an effect of this drug, usually disappearing within five to seven days, with return to normal levels (3 scale units, 5.5 gm weight, (Schi^tz) ; these pres­sure readings were confirmed by Maklakoff tonometric readings taken at the same time. In 1960, Becker and Constant reported a similar study. Subconjunctival injection of 2-PAM (2-pyridine aldoxime methiodide), atropine, and several alpha or beta adrener-gic blocking agents did not influence this level of pressure, but acetazolamide pro­duced immediate lowering of pressure to normal levels.

My results indicate that neither therapeu­tic effect nor side-effects can be predicted from assays of blood or serum cholinesterase levels in any animal. Serum cholinesterase in humans is "pseudo" cholinesterase, and is also the main enzyme present in ileum and liver. But it is of little significance, and is a mixture of enzymes which act on many substrates at high molar levels, while true acetylcholinesterase acts in minute concen­trations. Dr. de Roetth's report seems to rec­ommend isofluorophate because of its markedly low toxicity and its inability to in­activate enzyme everywhere in the body but the iris and ciliary body. My report con­cluded: "Isofulorophate (DFP) produced only relatively low levels of inhibition except in iris-ciliary body, where activity was inhib­ited to 30% of normal. At the end of 14