1098 AMERICAN JOURNAL OF OPHTHALMOLOGY DECEMBER, 1967

P. E. : An improved FTA test for syphilis : The ab­sorption procedure. Pub. Health Rep. 79:410, 1964.

4. Smith, J. L. and Taylor, W. H. : The FTA-ABS test in ocular and neurosyphilis. Am. J. Ophth. 60:653, 1965.

5. Smith, J. L. : Neuro-ophthalmology Sym­posium III. St. Louis, Mosby, 1967.

6. McDonald, P. R. and Purnell, J. E. : The dislocated lens JAMA 145:220, 1951.

7. Rodman, H. I. : Chronic open-angle glauco­ma associated with traumatic dislocation of the

The development of the Zeiss photocoag-ulator by Meyer-Schwickerath has made possible an attempt at selective obliteration of retinal vessels. The success of treatment has depended on the condition and the size of the vessels to be treated. Photocoagula-tion of small retinal angiomas, sickle-cell re-tinopathy, new vessels in Eales' disease and neovascularization following retinal vascular occlusion has been quite successful, while attempts to obliterate major retinal blood vessels and large abnormal vessels have been disappointing.

The purpose of this study was to deter­mine the effect of photocoagulation on the large retinal vessels, using the rabbit as an experimental animal, and to evaluate the efficacy of collapsing the vessel prior to pho­tocoagulation as an aid to obliteration.

To evaluate the reaction to photocoagula-tion of the large retinal vessels over the myelin fan, photocoagulation was applied to vessels normally filled with blood in the right eye of the animal; and then, photo-coagulation was applied to vessels collapsed by external pressure in the animal's left eye. The vessels lying on the myelin fan of the

lens: A new pathogenetic concept. Arch. Ophth. 69 :445, 1963.

8. Becker, B. and Hahn, K. A. : Topical corti-costeroids and heredity in primary open-angle glaucoma. Am. J. Ophth. 57:543, 1964.

9. Becker, B. : The effect of topical corticoste-roids in secondary glaucomas. Arch. Ophth. 72:769, 1964.

10. Armaly, M. F. : Symposium on Glaucoma, New Orleans Acad. Ophth. Feb. 1966.

11. Chandler, P. A.: Choice of treatment in dislocation of the lens. Arch. Ophth. 71:765, 1964.

rabbit offered an opportunity to utilize a fairly uniform absorbing background from animal to animal. It is recognized, however, that the white background of myelin per­mits much less absorption and burn than a pigmented background.

MATERIALS AND METHOD

Five pigmented (4.0 to 5.0 lb) male rab­bits were used, with the right eye receiving burns to the blood-filled vessels lying on the myelin fan. The burns were repeated in the same location on the left eye with the ves­sels collapsed by external pressure applied with a blunt glass rod. The Zeiss photocoag-ulator was set on green II with a 3.0-mm aperture opening and photocoagulation was applied for a period of one second. Every eye received a total of five individual burns in a linear manner, working along the course of the large retinal arteries and veins on the myelin fan (fig. 1). The rabbits were then killed at intervals of one, three and seven days, six and 12 weeks. Prior to death of the animals, each fundus was visualized through a dilated pupil using the indirect ophthalmoscope.

T H E EFFECTS O F PHOTOCOAGULATION ON THE LARGE RETINAL VESSELS OF THE RABBIT EYE

DONALD R. MILES, M.D. Phoenix, Arizona

AND RICHARD S. RUIZ, M.D.

Houston, Texas

VOL. 64, NO. 6 PHOTOCOAGULATION OF RETINAL VESSELS 1099

RESULTS

When the photocoagulation was applied to the blood-filled vessels, a shrinkage of both arteries and veins occurred, reducing them to fine ribbons. When the external pressure was released on the collapsed ves­sels, both the arterial and venous channels re-established their blood columns ; however, they appeared constricted similarly in the other eye. Clinical examination of the eyes indicated no difference between the two methods of treatment. Viewing the fundi at the one-day, three-day and seven-day peri­ods, the vessels appeared to dilate to their normal size in both eyes; however, a large amount of surrounding tissue damage was present. At six and at 12 weeks, the degen­eration of the underlying tissues was less

active, showing the formation of more glio-sis and fibrous tissue, with pigment migra­tion and accumulation at the margin of the lesions. The vessels appeared shrunken and the small branches of both the arteries and veins were obliterated in the area of the burn.

Upon histologie examination, no dif­ferences were evident between the eyes receiving photocoagulation in a collapsed state and the eyes receiving photocoagula-tion in their normal open state. The one-day sections from both eyes had a loss of the normal nuclei in the vessel wall with the lumen of the vein filled with polymorphonu-clear leukocytes (fig. 2) . This might be in­terpreted as a temporary fragile type of thrombus. The smaller lumen of the artery

Fig. 1 (Miles and Ruiz). Myelin fan as viewed through the dissecting microscope, seven days after photocoagulation. The burns were applied in a linear manner. Diffuse pigmentary clumping and retinal degeneration are present, extending inferiorly from the treated area. (Vertical section, Xl6)

1100 AMERICAN JOURNAL OF OPHTHALMOLOGY DECEMBER, 1967

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Fig. 2 (Miles and Ruiz). Marked migration of leukocytes into the artery and vein lumens, one day after photocoagulation. (Hematoxylin-eosin, X400.)

Fig. 3 (Miles and Ruiz). Thick­ened vessel walls with the lumen open and leukocytes infiltrating and adhering to the walls, three days after photocoagulation. (He­matoxylin-eosin, χ400.)

VOL. 64, NO. 6 PHOTOCOAGULATION OF RETINAL VESSELS 1101

showed an increase in the number of neu-trophils but remained open. After three days, the walls of both the arteries and veins were thickened and invaded by numer­ous round cells with the lumen of the vein being re-established. A migration of round cells was also seen in the underlying tissue in the proximity of the vessels (fig. 3) .

By seven days the outer layers of the ves­sels had fibrosis which was incorporated into the surrounding tissue. The lumen was open in the large veins and arteries in both eyes. Also evident was the partial-to-com­plete occlusion of the smaller branching vessels (fig. 4) . This same general picture was found at the six-week and 12-week in­tervals but with a greater amount of fibrotic tissue incorporating the vessels into the scarred area. The primary change between the six-week and 12-week sections was found to be the distortion and shrinkage of the lumen size of both the veins and arteries as the fibrotic scar tissue surrounding the vessels became more dense (fig. 5).

DISCUSSION

Meyer-Schwickerath1 suggested the possi­bility of partially collapsing the vessels

when applying photocoagulation for the treatment of Eales' disease in order to oblit­erate better the neovascular veil of vessels. Okun2 reported that he was unable to oc­clude the large retinal arteries of the dog, but that he was able to occlude the larger veins by first applying burns to the vessel distal and proximal to the planned site of occlusion and then proceeding with more intense photocoagulation to the vessel be-ween the original burns. This technique was utilized to diminish the flow of blood through the vessels prior to the final appli­cation. Campbell,3 working with cats, indi­cated that, following photocoagulation of the large veins, fragmentation of the blood col­umn and cessation of blood flow developed. He further stated that, if a second applica­tion of photocoagulation was then applied astride a segment of the broken blood col­umn, the vein was permanently occluded.

Therefore, by collapsing the vascular tree and applying a burn with photocoagulation, a more pronounced effect on the retinal ar­teries and veins is possible through three mechanisms: (1) an increased amount of energy would be directed toward the vessel wall due to the vessel's presenting a greater

Fig. 4 (Miles and Ruiz). Large vessel open with thickened wall of the arteriole and occluded small branch of the vein, seven days after photocoagulation. Note early formation of fibrotic tissue surround­ing the vessels. (Hematoxylin-eosin, χ400 )

1102 AMERICAN JOURNAL OF OPHTHALMOLOGY DECEMBER, 1967

Fig. 5 (MilCb and Ruiz). Shrunken, distorted large vessels surrounded by dense fibrous tissue, 12 weeks after photocoagulation. (Hematoxylin-eosin, X400.)

surface area when collapsed than when in its open tubular form ; (2) no diffusion of heat energy would occur by the circulation of blood passing through the vessel; (3) there would be no absorption or reflection of the light beam from the red column of blood.

Although these considerations would ap­pear to have a positive effect on the lesion produced on the vessel wall by photocoagu­lation, there were no clinical or histologie differences seen between the collapsed ves­sels and the blood-filled vessels. However, the most important factor may be the diam­eter of the vessel treated, since the smaller branches were occluded in both of the eyes. Since the volume of flow increases by the square of the vessel's radius, the lumen di­ameter would appear to be the most significant indicator for occlusion by photo-coagulation. This raises the interesting pos­sibility that, if the shrunken vessels ob­tained from the first application would re­ceive a second application of photocoagula-

tion, perhaps a final complete occlusion of these large vessels might result. It is further realized that perhaps a greater amount of light energy might also succeed in obliter­ating large vessels where the settings of green II, diaphragm O and aperture 3, have failed.

One problem encountered was the moder­ate amount of distortion of the cornea that occured when external pressure was applied to the eye. This distortion may have ac­counted for a partial dispersion of the energy applied although, clinically and histologically, the amount of reaction to the underlying myelin fan was the same in each of the eyes. One possible method to eliminate this dis­tortion and to have better control of the eye would be to use the suction ophthalmodyna-mometer described by Kukân* and modified by Linksz.5 This device would allow the pressure and the movement of the eye to be controlled to a much finer degree through its attachment by suction.

VOL. 64, NO. 6 PHOTOCOAGULATION OF RETINAL VESSELS 1103

SUMMARY

Photocoagulation was applied to the large vessels on the myelin fan of both eyes of five rabbits. In each rabbit, the vascular tree of one eye was collapsed by external pres­sure during the photocoagulation, while the other eye recived photocoagulation to the open vessels. No clinical or histologie differences were found in the two types of treatment over a 12-week period. Both types of treatment resulted in distortion and shrinkage of the large vessels, with the ves­sels remaining open. Dense fibrosis was evi­dent around these larger vessels, with occlu­sion occurring in the vessels with smaller diameters.

The retraction syndrome, described at the turn of the century (Stilling,1 Turk2'3 and Duane4) has interested many investigators. For a long time it was considered to be the result of a congenital anomaly of one of the horizontal muscles,5"9 although in only a limited number of cases was this opinion corroborated by observation during surgical procedures.

The first published report of an electro-myographic (EMG) study of this condition was by Breinin in 1957.10 Of his two cases, one revealed no electrical activity of the lat­eral rectus muscle at almost all sites ex­plored. Later (during surgical exploration), this muscle was found to be fibrotic. Other EMG studies11'12 also revealed lack of elec­trical activity or a very weak response in the lateral or medial rectus muscles of the affected eye.

Breinin's10 second case showed a para-

From the Departments of ophthalmology, Physi­cal Medicine and Rehabilitation, Hadassah Univer­sity Hospital.

555 West Catalina Drive 1121 Hermann Professional Building

(77025) REFERENCES

1. Meyer-Schwickerath, G. : Light Coagulation. (Translated by S. M. Drance.) St. Louis, Mosby, 1960, ed. 1 p. 74.

2. Okun, E. and Collins, E. M. : Histopatholo-gy of experimental photocoagulation in the dog eye : Part III : Microaneurysmlike formations following branch vein occlusion. Am. J. Ophth. 56:40, 1963.

3. Campbell, F. P. Retinal vein occlusion: An experimental study. Arch. Ophth. 65:26, 1961.

4. Kukân, F. : Ergebnisse der Blutdruckmes­sungen mit einem neuen Ophthalmodynamometer. Ztschr. f. Augenh. 90:166, 1936.

5. Linksz, A. : Improved model of the Kukân ophthalmodynamometer. Am. J. Ophth. 25:70S, 1942.

doxical innervation which was attributed to a "stretch reflex" of neurogenic origin.

During the last few years, several investi­gators have advocated a supranuclear lesion as the possible cause of the Stilling-Türk-Duane (STD) syndrome. This concept has been based mainly upon EMG proof of par­adoxical innervation detected in groups of antagonistic extraocular muscles. Some of these investigators13"17 found abnormal co-contraction of the horizontal rectus muscles, while others observed similar EMG abnor­mal co-contraction of either the lateral rec­tus and both vertical muscles18 or of the medial and inferior rectus muscles.19

On the other hand, it has been postulated recently that anomalies of the peripheral motor nerves serving the eye muscles could explain the paradoxical innervation in this condition.20 This has not been confirmed by EMG studies.

Despite the relatively high number of publications on the Stilling-Türk-Duane syndrome, including EMG studies, the ac-

AN ELECTROMYOGRAPHIC EVALUATION OF THE RETRACTION SYNDROME

H A N A N Z A U B E R M A N , M . D . , A L E X M A G O R A , M . D . , A N D J O S H U A C H A C O , M . D .

Jerusalem, Israel