Methods of Applying Pressure After Retrobulbar Block

METHODS OF APPLYING PRESSURE AFTER RETROBULBAR BLOCK

BYJose Berrocal, MD

WITH THE INCREASING POPULARITY OF INTRAOCULAR LENS IMPLANTATION, THE IM- portance of obtaining a soft eye during surgery has been recognized. Emphasis has been placed on applying low levels of pressure on the eye for a prolonged period, both before and after the retrobulbar block. Several different apparatuses have been utilized recently in an effort to obtain a soft eye. '3 Unfortunately, while attempting to obtain these optimum conditions, significant and permanent visual loss has occurred in a number of these cases due to impaired blood supply to both the retina and the choroid during the ocular compression phase. The purpose of this study was to compare the efficacy of two different methods of applying pressure after a retrobulbar block before cataract extractions. Two methods of applying pressure were used in this study: manual cycling pressure using the super pinkie rubber ball and automatic cycling pressure using the Keeler autopress unit. First, we selected the super pinkie rubber ball, since it had been the most frequently used compression apparatus in the United States over five years until the Honan instrument was introduced two years ago. Second, eight months ago, we selected the new Keeler autopress unit (Fig 1) and attempted to compare its results with those obtained using the super pinkie rubber ball method. The following parameters were compared between these two groups: 1) Reduction in intraocular pressure following cycling compression4 2) Completeness of the extraocular muscle paralysis 3) Incidence of vitreous loss5 4) Air trapped in the anterior chamber following cataract extraction 5) Incidence of optic atrophy Preoperative medication administered by the anesthesiologist consisted of oxymorphone Hcl (Numorphan) 0.5 mg IM and triflupromazine (Vesprin) 25 mg IM or hydroxyzine pamoate (Vistaril) 100 mg IM for the majority of the patients in this study. During surgery thiopental sodium

TR. AM. OPHTHI. Soc. vol. LXXIX, 1981 Retrobulbar Block 201 (Pentothal) 25 mg IV was used immediately after the retrobulbar block but prior to the modified Van Lint akinesia. In addition, Vistaril 50 mg IV, diazepam (Valium) 2.5 mg IV, and Pentothal 25 mg IV were used as required in order to keep the patient immobile. The retrobulbar block consisted of 3 cc of 4% lidocaine (Xylocaine) using an Atkinson retrobulbar needle, followed by 4 cc of intravenous Pentothal. Half a minute later, 10 cc of 2% Xylocaine were injected for the orbicularis muscle block. Post operatively the patients were unable to recall the orbicularis muscle block. The manual cycling pressure method used consisted of cycles of 20 seconds of pressure with a super pinkie rubber ball, followed by eight seconds of release or no pressure. These cycles were repeated for a total of seven minutes of alternating pressure. For the automatic cycling pressure method we used the automatic autopress unit from Diversatronics (Keeler). This machine allowed us to utilize exactly the same cycle as in the manual method. In addition, we were able to regulate precisely the amount of pressure exerted. This unit automatically applies regulated cycling pressure giving the surgeon exact control and monitoring over pressure height, duration of cycles, and total length of compression time. The ocular circulation is restored fully between compression phases for full retinal reoxygenation (8 seconds). With a built-in, "fail safe" mechanism, the unit turns itself off automatically in the event the pressure-on phase exceeds 25 seconds for any reason and it decompresses immediately if electrical current is inter- rupted. Compression and decompression proceed automatically and when the compression time is reached, the machine turns itself off and a signal bell rings. The compression balloon is made of soft expandable rubber material and is well tolerated by the patient. No leakage of air has been encountered since the company changed the design of its original balloon. The balloon remains accurately positioned by means of an adhesive sub- stance applied to this surface. This adhesive portion adheres to the rubber strip on the headband that also has an adhesive surface. We selected 70 millimeters of mercury as the pressure to apply, hope- fully trying to remain under the systolic pressure of the central retinal artery and, at the same time, above the diastolic pressure. In an effort to determine the pressure exerted with the rubber ball in the manual method, in several cases we substituted for the rubber ball both the Honan pressure regulator and the soft rubber compression balloon used with the automatic Keeler unit. We were satisfied that the pressure applied by these two techniques was essentially the same. With both techniques we obtained readings above 120 mm Hg. 202 Berrocal MATERIAL AND METHODS In 100 patients undergoing cataract surgery, the manual technique was used, in another 80 cataract patients, the automatic unit was used. All cataract patients over an 18-month period were included in this study except those patients with glaucoma or any other preoperative com- plication. One hundred eighty consecutive cases ofcataract surgery were included in this study. In the manual group, there were 43 men and 57 women while in the automatic group, 36 were men and 44 were women. Schi0tz tonometry was performed before the retrobulbar block and after seven minutes of cycling pressure utilizing either one of the two methods. The following results were recorded: 1) Reduction in intraocular pressure following cycling compression. An average reduction in intraocular pressure of 7 mm Hg (a decrease from 17 to 10 mm Hg) was obtained using the automatic method as compared to a reduction of 10 mm Hg (from 18 to 8 mm Hg) using the manual technique. Even more important was the finding that in 80% of the eyes in the manual group, the final pressure obtained was equal to or less than 10 mm Hg as compared to 60% ofthe eyes when using the automatic technique. 2) Completeness of the extraocular muscle paralysis. Extraocular muscle paralysis was complete in 90% ofthe eyes-on which the manual technique was used as compared with 80% of the eyes, on which the automatic method was used. 3) Incidence of vitreous loss. Vitreous loss occurred in 3% of the eyes on which the manual technique was used as compared to an incidence of 4% in the automatic group. 4) Air captured in the anterior chamber after the extraction. Air was captured in the anterior chamber in 68% of the eyes in the manual group as compared with 50% in the automatic group. 5) Incidence of optic atrophy following surgery. In 2% ofthe eyes subjected to the manual technique, optic atrophy was seen six weeks after surgery. There were no cases ofoptic atrophy in the eyes on which the automatic method was used. No abnormal pigmenta- tion was noticed in the periphery of the fundus. In one case, a 58-year-old man in good health, the best corrected vision obtained was 20/100. In the second case, an 82-year-old woman also in good health, the best corrected vision obtained was 20/400. Visual fields performed on both patients revealed an altitudinal field defect. Retrobulbar Block 203

COMMENTS 1) Both methods accomplished an adequate reduction in the intraocular pressure. The difference here was not statistically significant. 2) In both groups a high percentage of eyes obtained complete extraocular muscle paralysis. The difference here, also was not statistically significant. 3) The incidence of vitreous loss was maintained relatively low with either method. The difference was not statistically significant. 4) The manual technique was significantly more effective than the automatic method in capturing air inside the anterior chamber following cataract removal. 5) Unexplained optic atrophy following cataract surgery occurred only with the manual method (in two out of 100 eyes). Manual application of pressure is the most common procedure used throughout the world. However, manual pressure will vary depending upon the strength, weight, and technique ofthe physician or his assistant. The probability of the pressure applied exceeding the systolic pressure when using the manual technique might account for the occurrence of optic atrophy in these two cases.

CONCLUSION Both the manual method and the automatic method proved to be similar and consistent in obtaining an adequate retrobulbar block. However, we prefer to use the automatic method because of the two cases of optic atrophy that we encountered when using the manual method. The findings of this study has alerted us to the danger of inducing permanent visual loss due to impaired retinal and choroidal circulation when compressing the eyeball with the super pinkie rubber ball with an unregulated amount of pressure.

REFERENCES 1. Shepard D: Shepard ocular compressor, in Emery J, Jacobson A: Current Concepts in Cataract Surgery, Sixth Biennial Cataract Surgical Congress, St Louis, CV Mosby Co, 1980, pp 257. 2. Buys NS: Mercury balloon reducer for vitreous and orbital volume control, in Emery J, Jacobson A: Current Concepts in Cataract Surgey, Sixth Biennial Cataract Congress, St Louis, CV Mosby Co, 1980, pp 258-259. 3. Gills JP: Techniques of controlling intraocular pressure and reducing vitreous loss, in Emery J, Jacobson A: Current Concepts in Cataract Surgery, Sixth Biennial Cataract Congress, St Louis, CV Mosby Co, 1980, pp 260-262. 204 Berrocal 4. Jaffe NS: Digital pressure, in Jaffe NS: Cataract Surgery and Its Complications, St Louis, CV Mosby, 1981, pp 37. 5. Jaffe NS: Measures to prevent loss of vitreous, in Jaffe NS: Cataract Surgery and Its Complications, St Louis, CV Mosby Co, 1981, pp 256-258.

DISCUSSION DR A. EDWARD MAUMENEE. Undoubtedly one of the most important steps in intraocular surgery, expecially cataract surgery is the reduction of vitreous pressure. Doctor Berrocal is to be thanked for attempting to standardize and evaluate the effectiveness of two techniques. I do not know who first suggested external ocular pressure to reduce the ocular content before opening the eye. Walter Atkinson in his 1934 AOS thesis suggested placing intermittent pressure on the eye following retrobulbar injection but this appears to have been done more to defuse the anesthetic agent than to reduce intraocular content. Ralph Kirsch in 1956 is due credit for popularizing external ocular pressure to reduce ocular content. He gives credit in his opening paragraph to Paul Chandler for suggesting this procedure. Ron Hildrith in 1960 suggested that the mechanism by which the globe was softened from prolonged external pressure was the reduction in vitreous volume. He also thought that there was possibly some stretching of the sclera. David Kasner during the Cataract Congresses that were presented in Miami thought that another value of prolonged pressure was reducing the volume of the orbital content. Although measuring of intraocular pressure with a Schi0tz tonometer following prolonged pressure gives some indication of the effectiveness of external pressure, it accounts for only partial results. The reason for this is that the loss of aqueous from the anterior chamber is not the important factor and if one waits 10 or 15 minutes following pressure the aqueous may cause the intraocular pressure to be normal but when the globe is opened a spontaneous air bubble will occur in the anterior chamber with the iris falling backward illustrating that there has been a loss of vitreous volume. In addition one can observe quite easily the enophthalmous that occurs from prolonged ocular pressure eliminating the exophthalmous that occurs following a retrobulbar injection. Many techniques have been used for external ocular pressure. These have included finger massage, constant pressure with the palm of the hand or heel of the hand. The duration of this pressure has varied from constant to intermittent and the time from five to fifteen minutes. Doctor Gills at one of the Cataract Congresses in Miami suggested the use of a rubber ball commercially known as a "Super Pinky" through which a rubber band had been placed and the rubber band made large enough so that it would encircle the head. I used this technique for about four years but it necessitated someone standing by the patient and releasing the pressure every 15 seconds for 10 to 15 seconds to allow adequate retinal circulation. As Doctor Berrocal has stated this Retrobulbar Block 205 technique may produce as much as 160 mm Hg pressure on the globe and therefore must be removed intermittently. The Keeler auto press also gives intermittent pressure ofa much lower degree, which can be set anywhere from 20 to 60 millimeters of mercury. I used this on a trial basis and have found it to be no more effective than the Honan monometer and to be five to ten times more expensive. The Honan monometer is a relatively simple device consisting of a rubber bellows about an inch and a halfin diameter that is held in place over the globe by an adjustable rubber band. The bellows is inflated by a rubber bulb with an airway stop and this is connected to a guage that allows a fairly accurate adjust- ment of pressure to about 30 mm Hg. Doctor Walter Stark and I at the Wilmer Institute have used the Honan monometer to give gentle 30 mm pressure on the globe for a period of 20 minutes or longer in over a thousand patients on whom intraocular surgery was to be performed. I have found this to be so successful in reducing intraocular pressure that I have totally illiminated the use of mannatol. Doctor Stark and I have found no serious complications in the use of 30 mm constant pressure. Incidentally, early during the use of this technique, three patients who had phacoemulsification did have some evidence of retinal and choroidal eschemia but Doctor Stark and I are convinced this was not due to the 30 mm pressure on the globe. I have never been very happy with the use of intervenous mannitol to adjust the vitreous because of the danger of systemic effects and because of the dis- comfort of the full bladder caused from dyuresis that occurred so frequently in patients while being given mannitol. I am sure that the Honan monometer can be improved, for instance by adding safety factors that would prevent the pressure from being increased more than 30 millimeters on the globe and by altering the guage so that a more accurate measurement could be obtained. Nevertheless it is practical and I believe the best possible method of reducing vitreous pressure and orbital contents prior to cataract surgery. I am convinced that prolonged constant 30 mm pressure is far better than intermittent higher pressures and carries less danger of retinal and choroidal ischemia. DR J. TERRY ERNEST. There is reasonable evidence that the retinal circulation and the optic disc circulation autoregulate, that is to say, they adapt to elevated intraocular pressure levels; but there are two problems. The first is that the retinal blood flow is only autoregulated up to intraocular pressures of approximately 35 to 40 mm Hg. Above this level, the blood flow decreases and the result may be hypoxia. Second, it takes at least a minute for the regulatory process to take place so if the pressure in the eye is being elevated for just 10 or 15 seconds there will be no compensation and the circulation will be decreased. Thus it might be better to have prolonged pressure elevations below 35 mm Hg rather than intermittent pressures. Finally, though, I think the author should be con- gratulated for quantitating his intraocuolar pressure changes. It might also be reasonable to quantitate the length of time that the eye pressure is zero during 206 Berrocal open eye surgery. Intraocular lens implantation takes a relatively long period of time and once the intraocular pressure is below about 10 mm Hg the circulation cannot adapt. The result may be leakage as well as the occasional hemorrhage. DR HAROLD F. SPALTER. To be brief, retinal surgery is most critical at the time frame when injecting saline or air while observing the critical moment when an induced diastolic pulse at the central retinal artery may convert into no pulse at all. That is, you may easily go from diastolic pressure to over systolic. With a Honan balloon, intermittent balloon, or a rubber ball prohibiting the surgeon's view of the fundus, the central retinal artery systolic pressure can be exceeded without the surgeon's knowledge. One needs some sort of monitoring device that anticipates what the safe pressures are in the individual patient. One item that has not been discussed is that the anesthesiologist does have a display of the patient's systolic and diastolic blood pressure throughout the entire operative procedure and certainly available to you. For example, if we had a measureable 20, 30, 40 or 50 mm Hg on the eye with an oculopressor device and we see the patient's systemic diastolic pressure is in the 40 to 50 mm Hg level then you might have a potentially serious problem of excessive pressure on the central retinal artery. I would recommend, therefore, that at all times in setting these oculopressor dials you pay attention to the patient's diastolic pressure, divided approximately in half, which is a rough approximation of what the central retinal artery diastolic pressure would be and never exceed that figure. This allows the surgeon a margin of safety that he might not otherwise have. A recom- mended dial pressure of 30 mm Hg might be excessive in the patient with a systemic diastolic pressure of 50 mm Hg with a low pulse pressure. Therefore, settings should be individualized according to the patient's known systemic blood pressure to avoid iatrogenic intraocular vascular complications. DR MAX FORBES. The method of compressing the globe to lower intraocular pressure prior to cataract surgery represents an attempt to reduce the incidence of the so-called positive pressure phenomenon after the globe has been opened. I would like to call attention to the fact that as a mechanical system, the opened globe is quite different from the closed globe. Very little is actually known about the mechanics of the opened globe during intraocular surgery. There are three factors which are capable of causing the positive pressure phenomenon during surgery, namely, an increase in the volume ofthe intraocular contents, collapse of the scleral shell or an external force impinging on the globe with resultant forward thrust of the intraocular contents. Hence, we are working with a rather complex system in the sense that the cause of positive pressure during surgery is not always evident and we are often unable to anticipate which eyes will manifest this phenomenon. I have no doubt that preoperative compression and softening of the globe is helpful to some extent, but it is not uniformly successful and it is often un- necessary. I would, therefore, like to make a plea for more intensive study of the mechanics of the opened globe so that we can identify which eyes are likely to Retrobulbar Block 207 have this problem and take appropriate countermeasures. It would certainly be preferable not to use ocular compression when it is not needed. DR HAROLD GIFFORD. Doctor Forbes just stole my thunder. This is just exactly what I was going to point out. Intraocular pressure when the eye is intact is one thing but the pressure when you open the eye goes to zero. Well it is atmospheric pressure. Then the forces act on the globe just like a paper bag. The forces that produce vitreous loss from now on are mainly orbital. They are first the lids, and the heavy handed surgeon and his heavy handed assistant. These are the things that you have to look for. I wrote a paper on this in 1946 and have been working on it ever since. There are at least six different factors. The main factor, I believe is the lids. A complete facial block is the most important thing. There is a special protective reflex, the reflex reaction to fear that causes squeezing of the lids and retraction of the globe. Many mammals have a retractor bulbi muscle. I believe that this muscle is present in some extent in humans. Setting off this reflex will produce explosive vitreous loss. Also, the extraocular muscles must all be relaxed. Oblique muscles pull forward and the recti pull backward, this is just like squeezing a ball. These muscles must be completely relaxed with complete loss of their normal tone. To measure these forces the lens iris diaphram must be watched carefully. If you are operating with a small pupil you can see this diaphram push forward or drop back, or remain level. When the iris diaphram pushes forward you have positive vitreous pressure and if the diaphram continues to come forward you must be very careful. You should try to find out why there is positive pressure. Check the lid block. Check the speculum. Ifthe speculum is pushing on the globe put in a smaller speculum. There are other things that you can do. Check the motor block of the extraocular muscles. With the retrobulbar needle still in place you can add a little more anesthetic, but not too much or you will produce more pressure. The last resort is to remove some of the vitreous by a needle puncture into the vitreous cavity. There are two other sources of pressure; hemorrhage in the choroid or simply intumescence, and hemorrhage in the orbit. I have no advice for lowering the choroidal pressure, perhaps adrenalin in the retrobulbar block helps. Orbital hemorrhage both arterial and venous can be largely controlled by using a blunted needle. Simply hone offthe sharp tip and the knife edges ofthe needle. With this type of needle I have personally not had an orbital hemorrhage. DR GEORGE SPAETH. I would like to ask Doctor Berrocal a question. About 10 or 15 years ago Doctor Wallace Foulds, in Glasgow, showed that raising the intraocular pressure to 40 mm of mercury using an ophthalmodynamometer will produce significant changes in the blue-yellow color vision that last up to about six months. These experiments, I believe, were done on his own eye. In view of the sen- sitivity of the eye and the insensitivity of visible optic atrophy as a measure of visual functioning, together with Doctor Maumenee's comment that pressures around 30 mm Hg seem to be adequate to decrease vitreous volume, is not a pressure of 70 mm Hg higher than ideal? 208 Berrocal DR STEVEN G. KRAMER. I just wanted to comment about the two cases of optic atrophy that were reported. There were evidently two in the series of manual pressure eyes and none in the series of cases that had had automatic pressure. I think it's worthwile to bring out the possible danger ofirreversible visual loss with compression of the eye, but I don't think that those numbers incriminate either one approach or the other. It is very unlikely that there is a statistically significant difference between the groups, and there could have been many other uncon- trolled differences between them. It's worth being cautious about compression, but I don't think the paper has justifiably concluded that automatic compression causes less irreversible vision loss than does manual compression. DR FRONCIE A. GUTMAN. I do not believe that there is an absolute safe intraocular pressure which will prevent a closure of the central retinal artery. During retinal detachmant surgery I have observed two patients who had transient closure of the central retinal artery with intraocular pressures of 18 and 24 mm Hg respectively. Both ofthese patients had asymptomatic carotid stenotic disease with low ophthalmic artery perfusion pressures ipsilateral to the eye I was operating upon. This may constitute an unrecognized variable in a given patient. Doctor Kramer alluded to the other point I wanted to make. Unexplained optic atrophy following cataract surgery may be a consequence ofthe retrobulbar injection needle impact- ing upon the optic n4erve. I have never seen this written about but I am sure that it can happen. DR CHARLES ILIFF. Surgeons who lose vitreous during cataract surgery should reevaluate their technique. A preoperative soft eye is essential and pressure on the globe at the time of surgery must be avoided. Manual pressure over the globe as described first by Kirsch and later by Iliff ("A Surgically Soft Eye by Posterior Sclerotomy" Am J Ophthalmol 61:276, 1966) gives just as good results as does expensive machines currently touted as the answer to all problems. The white disc described by Doctor Berrocal that followed cataract extraction more likely resulted from the anesthesia injection hitting the nerve during the retrobulbar anesthesia rather than from pressure changes in the eye. DR JORGE A. ALVARADO. Doctor Gifford reminded us that there are many factors outside the globe which participate in the regulation of the intraocular pressure (IOP). As he described in 1949, some of these external factors are disturbed by retrobulbar anesthesia, resulting in alterations of the IOP. I have been interested in one of these external factors; namely, the extraocular muscles (EOM's) and their response to the local anesthetics used for retrobulbar anesthesia. My inter- est was stimulated by our laboratory observation indicating that local anesthetics may produce contraction of the EOM's. Perhaps our findings, which I will de- scribe briefly here, will stimulate an evaluation of the response of human EOM's to local anesthetics and the effect on the IOP at surgery. We noted that cat and monkey EOM's develop a rise in tension when bathed with 1% procaine or 2% lidocaine (Xylocaine). While other skeletal muscles failed Retrobulbar Block 209 to respond when bathed in a similar manner with procaine, they did respond when Xylocaine was used. Administration of Xylocaine in the retrobulbar space produced a dose-dependent rise in intraocular pressure. In most cases, this pressure rise occurred ten minutes after the retrobulbar injection was given. There is one study in the literature where the IOP in patients was measured up to 10 minutes after the retrobulbar injection. Here the authors were unable to show a decrease in the IOP following retrobulbar anesthesia. Most interesting is the fact that by ten minutes after the retrobulbar injection, the intraocular pressure oftheir patients was rising. Such a late, gradual rise in IOP closely resembles that which we observed in cats and monkeys as described above. Whether the EOM's are an "external factor" that could produce an IOP rise following retrobulbar anesthesia using Xylocaine in patients remains to be shown. In any case, retro-placement of the globe, such as achieved by massaging or placing pressure on the eye, as shown by Doctor Berrocal, is an effective way to abolish a pressure rise related to contraction of the EOM's. DR ROBERT C. DREWs. The concept of the "soft eye" is one of the great advances in cataract surgery and lens implantation. A number of schemes and devices have been proposed to achieve this, ranging from simple application ofpressure by the hand of the surgeon or one ofhis assistants, to expensive and complex equipment which automatically regulates the amount and duration of the pressure being applied with preset periods of reapplication. I would urge you to look at these various pieces ofequipment not only from the standpoint of cost but also from the standpoint of what they do to the patient's eye. I would recommend that you try these devices on yourselffirst before using them on your patients. If you apply a super pinky ball to your own eye, for example, you will find that this is painful and brutal. A balloon pumped up so as to press against the eye with a pressure of 30 mm Hg is also surprisingly firm. In my own hands I have found that a Nerf Ball is a very gentle, effective and inexpensive solution. These are the small, very soft sponge rubber balls that children use in wading pools. They are obtainable in many dime stores and discount stores. The ones that are about 3 inches in diameter are the right size. They can be gas sterilized. We apply them simply by passing a strip of tape around the patient's head and taping the sterile Nerf Ball in place after the patient's lids have been prepped. It should be left in place 8 to 12 minutes. Such a soft sponge rubber ball applies gentle pressure evenly across the globe and orbit, is quite safe, very effective, and-in this day ofincreasingly expensive ophthalmic equipment-remarkably inexpensive. DR JAMES ELLIOT. I just wanted to make two quick comments. Those of us who spent some of our days in training in Boston, either all of it or part of it, always gave Doctor Paul Chandler original credit for innovating ocular massage. Whether that's true or not I'm not sure. Doctor Chandler took credit for it at least. The second thing is with regard to the optic atrophy. Many many years ago Doctor Frank Carroll reported an incidence ofsomewhere in the neighborhood of 210 BerrocalBroa 2% optic atrophy following routine cataract extraction and he gave multiple causes for that at that time so I don't think it's fair to blame that totally as Doctor Berrocal did on his ocular massage technique. DR WILLIAM F. HUGHES. I think we might as well set a record! I once operated on a neurotic neurologist for cataract extraction, and made a 2 ml retrobulbar injection of 2% Xylocaine, followed by intermittent massage manually, and he lost all light perception. From under the drapes he said, "you might as well stop the operation because you've had an expulsive hemorrhage." Regardless, we went ahead with the operation and no complications resulted such as occlusion of the central retinal artery or optic atrophy. It must be possible to anesthetize the optic nerve by retrobulbar anesthesia. DR Jost BERROCAL. I talked to Doctor Norton last night and told him that I didn't know ifmy paper was any good or not but I thought I would fill the front row and I did. I appreciate all your comments, and I hope to go back and start working with these suggestions, especially Doctor Spalter's idea of watching the diastolic pressure; secondly, my thanks to Doctor Maumenee for his discussion. In regard to Doctor Maumenee's comment that he thinks the Honan apparatus is better, they are intended for two different purposes. The Honan is intended for constant pressure and that's what my difficulty was. I tried to set it on a specific reading on the dial but then when I released it it didn't hold at that setting. However, the Honan is the machine if you want to do constant pressure. As to the price, it is $1,500 not $2,500 but we are holding inflation here a little bit. I certainly was in Boston at the time that Doctor Elliot was and I was very impressed. I would go and watch the old master, Doctor Paul Chandler, do his glaucoma and cataract operation and I was impressed by good work and the way he did his surgery, and the way he massaged. When I went back to Puerto Rico I tried to apply pressure intermittently.