VOL. 78, NO. 2 NOTES, CASES, INSTRUMENTS 329

R E F E R E N C E

Figure (Newell). A simple eyelid retractor using rubber bands clamped to the drape for retraction.

claved with the retractor. Each rubber band is clipped to the drape with a small hemo-stat outside the operating field and provides uniform retraction and tension.

S U M M A R Y

A rubber band attached to a small eyelid retractor and clipped to the drape outside the operating field provides uniform retrac­tion and tension and excellent ocular ex­posure.

1. Jaffe, N. S.: Cataract Surgery and Its Com­plications. St. Louis, C. V. Mosby, 1972, p. 47.

E V A L U A T I O N O F A N I M P R O V E D U L T R A V I O L E T T O N O M E T E R

S T E R I L I Z E R

SPENCER E. S H E R M A N , M.D.

New York, New York

A new ultraviolet-ozone sterilizer de­veloped by the Sklar Manufacturing Com­pany was tested for its germicidal property to kill bacteria and fungi. The ultraviolet por­tion is enclosed in an aluminum housing. The mounting bracket for the tonometer and the dust cover are Lucite. To produce the germicidal effect, electrons travel across a tungsten filament in an atmosphere of mer­cury vapor from a 4 -W mercury bulb, t rans­mitting ultraviolet radiation and producing ozone close to the bulb. This sterilizer has the following new features: (1 ) a variable timing mechanism that allows exposure at 10-, 15-, and 20-minute intervals; and (2 ) a safety interlock mechanism that automatically cuts off the power supply and ultraviolet radi­ation when the case is opened to change the bulb.

M E T H O D

T o test the effectiveness of the Sklar tonometer sterilizer, various bacterial isolates, some from ocular infections, were collected from hospitalized patients. Pure cultures were at first obtained on a suitable solid cul­ture medium, such as blood agar plates, after which subcultures of the isolates were pre­pared in fresh 1.5% trypticase soy broth, p H 7.0. After overnight incubation at 37°C, optical density readings (measured with a

From the Department of Ophthalmology, Mount Sinai School of Medicine of the City University of

' New York. Reprint requests to Spencer E. Sherman, M.D.,

166 E. 63rd St., New York, NY 10021.

330 AMERICAN JOURNAL OF OPHTHALMOLOGY AUGUST, 1974

TABLE

GERMICIDAL EFFECT OF STERILIZER ON BACTERIA AND FUNGI*

Bacterial Isolates

Exposure Time (min) to the Ultraviolet Light and Ozone

1 3 5 10 IS 20

BA BR BA BR BA BR BA BR BA BR BA BR

+ + + + + + - - - - - -+ + + + + + - - - - - -+ + + + + + + + - - - -+ + + + + + - + + + - -+ + + + + + - + - - - -+ + + + + - + - + + - -+ + + + + - - - - - - -+ + + + + + - - - - - -+ + + + + + - - - - - -+ + + + + + - + - - - -

Proteus mirabilis Escherichia coli Klebsiella aerogenes Serratia marcescens Pseudomonas pyocyaneus Beta-hemolytic streptococcus Enterococcus Staphylococcus aureus Candida species Mixed culture Tonometer control

BA signifies blood agar; BR, broth; —, negative culture; and + , positive culture.

Lumetron photoelectric nephalometer, using a 580 mu. filter) were made of the isolates, after which further subcultures were pre­pared to ensure purity and viability of the bacterial isolates. The cultures were diluted to contain approximately 1.5 X 105 organisms per milliliter by colony count. An aliquot, about 5 ml, from each of the broth cultures of the isolates was placed in a separate sterile petri dish just prior to testing.

Before using the tonometer sterilizer in the effectivity procedures, the ultraviolet light was switched on for ten minutes. After this period of exposure to the ultraviolet light, the tonometer head was swabbed and cultures were made on blood agar and into broth. This procedure ensured that the tonometer head was not contaminated before the start of test­ing.

The tonometer head was dipped into the petri dish containing the bacterial culture un­der test for ten to 15 seconds. Surplus culture material was removed with a sterile swab, the contaminated tonometer head was placed in the sterilizer, and the ultraviolet light switched on. The contaminated tonometer head was swabbed at intervals varying from one to 20 minutes after exposure to the ultra­violet light and ozone. The swab was inocu­lated onto a blood agar plate and placed in

broth. This cultural procedure was repeated after each exposure to ultraviolet light at the various time periods and with the bacterial isolate used in the evaluation procedure. All the inoculated blood agar plates and broth cultures were incubated at 37°C and then ex­amined macroscopically after 24- and 48-hour incubation periods.

The Table summarizes all results.

SUMMARY

An improved ultraviolet-ozone sterilizer was tested for its germicidal property to kill bacteria and fungi. The contaminated to­nometer head (previously immersed in the test culture) was exposed to ultraviolet light and ozone for specific time periods. No or­ganisms survived the exposure to the ultra­violet light and ozone after 20 minutes. The advantages of the new Sklar ultraviolet-ozone sterilizer are the variable timing mechanism and a safety mechanism effective while chang­ing the bulb.

ACKNOWLEDGMENT

I thank Gerard L. Boyle for his assistance with the laboratory results.