The Effect of a Contact Lens on the Content of Carbon Dioxide in the Aqueous Humor*

The Effect of a Contact Lens on the Content of Carbon Dioxide in the Aqueous Humor*

718 FREDERICK C. BLODI AND JOSEPH C. YARBROUGH fat-laden macrophages with cholesterol clefts and Touton giant cells. The usual xanthelasmas or plain...

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718

FREDERICK C. BLODI AND JOSEPH C. YARBROUGH

fat-laden macrophages with cholesterol clefts and Touton giant cells. The usual xanthelasmas or plain xanthomas of the lids were also observed in our family. 3. An interesting finding were the nu­ merous glistening crystals in the fundus of patient II/4. Similar crystals may, of course, be observed in other older patients especially after retinal or subretinal hem­ orrhages. However, in this patient they were unusually numerous and occupied large areas of the posterior pole. The assumption is that they are also cholesterol crystals, though histologie proof is missing. SUMMARY

A family with idiopathic hypercholesterolemia is reported. The members of two

generations could be examined. While the members of both generations were affected by this disorder, only members of the older generation showed ocular complica­ tions. Senile arcus was observed and though it was clinically most marked in its appear­ ance, it occurred only at an age where the gerontoxon is also observed in patients with normal cholesterol level. In addition to the usual xanthelasmas, tuberous xanthomas of the lids were seen in one patient. Histologie examination of this lesion revealed the typi­ cal accumulation of foam cells, Touton giant cells and cholesterol crystals. In one other patient we observed numerous glistening crystals, presumably cholesterol, in the fun­ dus. University Hospitals.

REFERENCES

1. Lindholm, H.: Arcus lipoides corneae and arteriosclerosis. Acta Med. Scand., 168:45, 1960. 2. Finley, J. K., Berkowitz, D., and Croll, M. N.: The physiologic significance of gerontoxon. AMA Arch. Ophth., 66:211, 1961. 3. Adlersberg, D.: Hypercholesteremia with predisposition to arteriosclerosis. Am. J. Med., 11:600, 1951. 4. Schettler, G., and Dietrich, F.: Die Bedeutung von Xanthomen und Xanthelasmen für die Atherosklerose. Klin. Wchnschr., 31:1040, 1953. 5a. Lewis, N.: Ocular pathology in a case of xanthomatous biliary cirrhosis with intraocular involve­ ment. Brit. J. Ophth., 36:325, 1952. 5b. Brown, R. A.: Lesions of the retina and macula associated with hypercholesterolemia. Southern M. J., 52:204, 1959. 6a. Pajtas, J.: Obrovsky tuberozny xantom mihalnic obidvoch oci a ich sirokeho okolia; Cechosl. Of tal., 13:164, 1957. 6b. Chatterjee, B. M.: Essential xanthomatosis. Am. J. Ophth., 54:310, 1962. THE EFFECT OF A CONTACT LENS ON T H E CONTENT CARBON DIOXIDE IN T H E A Q U E O U S H U M O R * C L E M E N T M C C U L L O C H , M.D.,

AND I N G R I D F I E L D I N G ,

OF

M.T.

Toronto, Ontario

The influence of a contact lens on the metabolic processes in the eye has been in­ vestigated by several workers. Smelser and Ozanics1 showed the importance of atmos­ pheric oxygen for the maintenance of the op­ tical properties of the cornea. Smelser2 also found that deficiency of oxygen results in * From the Department of Ophthalmology, Faculty of Medicine, University of Toronto. This study was supported by a Public Health Grant, No. 605-7-151.

corneal edema. McCulloch and Morley3 showed an increase of lactic acid in the cor­ nea under a contact lens. McCulloch4 reported that bubbles appear under a contact lens when the wearer goes to low atmospheric pressure. The content of these bubbles is not known, but one of the important gases present may be carbon di­ oxide. If there is significant loss of carbon dioxide from the eye through the cornea, this would be decreased on wearing a contact lens

CARBON DIOXIDE IN AQUEOUS HUMOR

719

TABLE 1

TABLE 2

COa CONTENT IN RABBIT AQUEOUS EXPRESSED IN MILLIMOLS GAS PER LITER

CO2 CONTENT IN RABBIT AQUEOUS EXPRESSED IN MILLIMOLS GAS PER LITER

(contact lens wearing time 24 hours) No. Under contact lens Control

Mean

Difference Stand­ ard from Mean Deviation

Time (hr.) Ì1 2

6 6

30.9 29.5

±1.7 ±2.6

1.94 2.82

and a rise in carbon dioxide content of the aqueous would occur. These experiments were carried out to deAt the end of the wearing time aqueous was withdrawn from either eye and carbon di­ oxide estimations were made by the method of Scholander and co-workers5 and the Natelson micromanometric method.® RESULTS

The carbon-dioxide content in the anterior chamber after 24 hours is shown in Table 1. There is no significant difference between the levels in the experimental and control eyes. Carbon-dioxide content of the aqueous in eyes carrying the contact lens for shorter pe­ riods than 24 hours and in control eyes is shown in Table 2. There is no significant difference between the levels in the experi­ mental and control eyes at any of these times. DISCUSSION

Wearing of a contact lens presumably retermine the C 0 2 content in the aqueous of rabbits eyes with or without contact lenses in place. METHOD

Six groups of adult albino rabbits weigh­ ing approximately 1.6 to 2.1 kg. were used. The contact lenses, fitted from five stock sizes and averaging 11.6 mm. in diameter,

1 1 2 3 3 5 S 24 24

Eye with Contact Lens

Eye without Contact Lens

Lens-Control

30.5 29.1 28.8 34.4 31.5 34.8 29.0 28.4 30.2 30.8 31.7

30.9 27.7 29.8 36.1 31.5 32.9 29.0 29.1 29.3 30.1 33.4

-0.4 + 1.4 -1.0 -1.7 -0.0 +1.9 0.0 -0.7 +0.9 +0.7 -1.7

were put over the right eyes; the left eyes were used as controls. The animals in the five groups wore the contact lenses as fol­ lows: Group A, 30 minutes ; group B, one hour ; group C, two hours ; group D, three hours ; group E, five hours and group G, 24 hours. duces the oxygen supply to the cornea. This would reduce oxidative processes, increase lactic acid formation and reduce carbon di­ oxide production. If carbon dioxide normally leaves the anterior chamber through the cor­ nea this would be hindered by the contact lens, increasing carbon dioxide content in the aqueous. These factors may be only two of many involved in establishing the aqueous carbon dioxide content under a contact lens. Apparently the factors increasing and those decreasing aqueous carbon dioxide under a contact lens balance each other, resulting in no significant change in the concentration of gas in the anterior chamber. 100 College Street (5). ACKNOWLEDGMENT

We wish to thank Dr. Everett Kinsey and Dr. D. V. N. Reddy for their co-operation and ad­ vice in this work.

REFERENCES

1. Smelser, G. K., and Ozanics, V.: The importance of atmospheric oxygen for maintenance of the optical properties of the human cornea. Science, 115:140, 1952. 2. Smelser, G. K.: Relations of factors involved in maintenance of optical properties of cornea to contact lens wear. AMA Arch. Ophth., 47:328, 1952. 3. McCulloch, J. C, and Morley, N. H. : Lactic acid and oxidized pyridine nucleotides in cornea of rabbits wearing contact lenses, AMA Arch. Ophth., 66:113, 1961.

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CLEMENT McCULLOCH AND INGRID FIELDING

4. McCulloch, J. C. : The acceptance of contact lenses in military personnel, Aeromedicai Reports, R.C.A.F., 1, 1961. 5. Scholander, P. F., Claff, L. C, Andrews, F., and Wallach, D. F.: Microvolumetric respiratory. J. Gen. Physiol., 35:375, 1952. 6. Natelson, S.: Routine use of ultramicro methods in the clinical laboratory. Am. J. Clin. Path., 21:1153, 1951.

INFLUENCE OF POSITION ON INTRAOCULAR

PRESSURE*

M I L E S A. G A L I N , * M.D., J O H N W . MCIVOR,* A N D G. B R O C K MAGRUDER, M . D .

New York

Measurements of intraocular pressure in the same patient may differ when obtained by indentation (Schijzitz) and by applanation tonometry.1 Part of this discrepancy has been attributed to positional differences ne­ cessitated by the two techniques.2 In inden­ tation tonometry the patient is usually semirecumbent, while in applanation tonometry he is erect. Most measurements of intraocular pres­ sures in the recumbent and erect positions have been compared by using the Schijftz tonometer for the former position and the applanation tonometer for the latter.3 It would be advantageous, however, to utilize a single instrument to assess the true effects of positional differences on intraocular pres­ sure. The Schi^tz tonometer is not well suited for such a study because of the con­ sideration of ocular rigidity as well as the difficulty of using this instrument with the patient erect. The applanation tonometer, however, is readily adaptable for use both in the supine and erect positions with but minor adjustments to the supporting slitlamp. This communication reports a comparison of applanation measurements of intraocular pressure in patients in the erect and supine positions. ♦From the Department of Surgery (Ophthal­ mology) of the New York Hospital-Cornell Medi­ cal Center. This study was aided by Research Grant No. B-3010 (Rl) from the National Insti­ tutes of Health and by a tFight for Sight Sum­ mer Student Fellowship of the National Council to Combat Blindness. t Career scientist, Health Research Council, New York, New York.

MATERIALS AND METHODS

Twenty consecutive patients attending the Ophthalmology Clinic of the New York Hos­ pital-Cornell Medical Center were studied. A calibrated Goldmann applanation tonometer attached to a Haag-Streit slitlamp was uti­ lized for all patients. The patients were seen on several occasions so that they were well oriented to applanation tonometry. On the day of experimentation, applana­ tion readings were first obtained with the patient in the erect position (fig. 1). The patient was then positioned on his left side on a flat table with a single, thin, stiff pil­ low supporting his head so that the left eye was at the same level as the sternal angle of Louis. The slitlamp, with the front grill removed, was moved to the table side and the patient's intraocular pressure recorded in both eyes (fig. 2) within three minutes of his assuming the supine position. The pa­ tient was then positioned on his back and allowed to remain thus for 20 minutes. The intraocular pressure was then recorded once more after the patient had rolled to his left side. RESULTS

Table 1 compares the erect and supine ap­ planation measurements in the same patients for the one-to-three and 20-minute periods. It is apparent that the intraocular pressure is significantly higher in the supine than in the erect position. The average pressure changes for this group are listed in Table 2. DISCUSSION

Investigators have long recognized the