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VOL. 64, NO. 2 CORRESPONDENCE 325
trations of local corticosteroids to prevent recurrent corneal inflammation. Irvine (A. Ray, Jr., Los Angeles) showed a dramatic time-lapse motion picture of the toxic effects of leukocytes and leukocyte lysosomes on tissue culture of the corneal endothelium.
Maumenee and von Noorden presented three cases of irreversible visual loss which followed deprivation of form vision by opacities of the anterior segment. Sheppard, Shanklin and Fox demonstrated a striking increase in number of cells with morphologic changes in the buphthalmic rabbit eye. Anderson, Hoyt and Hogan discussed the fine structure of the optic nerve and showed a beautiful demonstration of alternating fibers in the lamina cribrosa. Dixon showed nonsymptomatic corneal stromal vasculari-zation in wearers of contact lenses which he attributed to prolonged wearing time and lenses resting on the limbus.
Locke presented 237 patients with vertical muscle imbalance in which the blindspot on perimetry was displaced either upward or downward from its normal location, indicating a cyclotropia. Hedges presented a family in which four members had loss of accommodation and a dilated pupil which did not react to light but did react to near stimuli. After about six months, the dener-vation hypersensitivity could be demonstrated with mecholyl.
The meeting again concluded with a fine sense of increased clinical skill and an awareness of subtle aspects of diagnosis contributed by outstanding physicians. The next meeting will be held at the Homestead, May 27, 28, and 29, 1968.
Frank W. Newell
CORRESPONDENCE TRAINING OF PHYSICIANS' ASSISTANTS
Editor, American Journal of Ophthalmology:
In January of this year I attended the Association of University Professors of
Ophthalmology meeting in Phoenix, Arizona. I was impressed with the objectives and efforts of the association and its various working committees. Military ophthalmology and civilian ophthalmology have several areas of mutual interest, including the training of residents, the continued training of ophthalmologists after residency and Board certification and the procurement of and training of ophthalmic assistants. This letter pertains to the Army's program for training ophthalmic assistants.
In 1965, the Army established a new Military Occupation Specialty (MOS 91U) for enlisted personnel who serve as EENT specialists. The need was for approximately 350 and only about 200 enlisted personnel, then working in the EENT field, fulfilled the requirements to obtain this MOS. Therefore, a training program was formulated by Walter Reed General Hospital. A pilot course was given for six students at Walter Reed General Hospital in January, 1966. In April, 1966, two other Army hospitals entered the program. Hospitals with residency programs in both ophthalmology and otolaryngology were selected for the training program in order to have instructors available. A fringe benefit of this program has been to give the residents some additional speaking and teaching experience. As a prerequisite to take the course, a student must be qualified as a medical corps-man. This requires an initial 10 weeks at the Medical Field Service School.
The 91U program is a 12-week formal on-the-job training course; six weeks are spent in the Eye Clinic and six weeks in the E N T Clinic. The course is given four times a year at the three hospitals and each class has six to eight students. The goal is to train the number necessary to fulfill and maintain the needs. It is probable that the majority of these 91U specialists will leave the service after two or three years service, necessitating a permanent training program and possibly augmentation of present capabilities. I anticipate the training of at least
326 AMERICAN JOURNAL OF OPHTHALMOLOGY AUGUST, 1967
100 91TJ personnel each year will be required to maintain the needs.
A training manual has been prepared for these technicians. Lectures given cover basic subjects in ophthalmology and otolaryngolo-gy. The OJT portion of the eye course stresses vision testing, visual field performance, tonometry, neutralization of lenses, fitting and ordering of spectacles, and assisting the doctor with patient care in the clinic. The students are trained to remove conjunctival foreign bodies, instill medications, and to accomplish other similar procedures. These personnel then work in this field during their service duty and are especially valuable assistants at Army Eye and ENT clinics.
At retirement, or after completion of their service obligation, many of these technicians would be ideal candidates for positions as ophthalmic assistants to civilian ophthalmologists. Some agency is needed that can gather and provide information on both ophthalmic assistant opportunities and on available applicants. Possibly civilian ophthalmology can provide this agency. Once provided, the Armed Services undoubtedly can furnish this information to the applicable personnel leaving the service for civilian life.
Jack W. Passmore Washington, D.C.
CRYOGENIC THERAPY OF HERPES KERATITIS
Editor, American Journal of Ophthalmology :
In the March issue (Am. J. Ophth. 63:399, 1967) M. E. Corwin, R. L. Cope-land and S. Birnbaum reported their results in experimentally produced herpetic keratitis treated with cryogenic technique.
In this carefully controlled experiment, the authors obtained a negative result with the application of a cryostylet at a temperature of —20°C. This negative result could have been predicted because (1) the optimal temperature for inactivating virus is —40°C, and
(2) the instrument was apparently not thawed before it was removed from the cornea.
Since the instrument temperature used by Corwin was — 20° C, it must then be assumed that the actual temperature at the point of contact with the warm cornea was considerably higher, so that instead of — 20°C, he was actually using a temperature of —5° to — 10°C. When the solid carbon dioxide instrument is used, with a temperature of — 79°C, the temperature at the point of contact is -40°C.
Greiff (Cryobiology, Merryman, editor, 1966, pages 697-728) has demonstrated that there is a marked reduction in virus concentration following rapid freezing at — 40°C and equally rapid thawing, in a quick succession of repeated applications. For example, if the initial concentration of virus is 1,000,000 it would be reduced to 400,000 after the first application of freezing, and to perhaps 10,000 after the second cycle of freezing and thawing. Only a few viruses survive the third freezing process.
If the instrument is not thawed before lifting it from the cornea, it removes the epithelium adhering to the instrument. In doing this, the valuable antiviral interferon formed in the epithelial cells is lost. Instead, by thawing the instrument before removing it, the ophthalmologist leaves the infected cells (that have been disrupted by freezing) on the cornea. This allows the interferon to enter the uninfected epithelial cells, where it prevents the replication of the few surviving viruses that may enter these cells.
Another factor that may not have been considered is the anatomic difference between the rabbit and human cornea. The absence of Bowman's membrane in the rabbit would lead to a more rapid scarring of the animal's cornea.
Finally, Krwawicz (Brit. J. Ophth. 49:37, 1965) and others (Society for Cryo-Ophthal-mology meeting, January, 1967) reported on low-temperature treatment in several hun-