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ARTICLE
Year : 1963  |  Volume : 11  |  Issue : 3  |  Page : 58-61

Ascorbic acid in aqueous and serum in normal and mature cataractous Indian patients


Department of Ophthalmology, G. R. Medical College, Gwalior, India

Date of Web Publication28-Jan-2008

Correspondence Address:
H V Nema
Department of Ophthalmology, G. R. Medical College, Gwalior
India
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Source of Support: None, Conflict of Interest: None


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How to cite this article:
Nema H V, Srivastava S P. Ascorbic acid in aqueous and serum in normal and mature cataractous Indian patients. Indian J Ophthalmol 1963;11:58-61

How to cite this URL:
Nema H V, Srivastava S P. Ascorbic acid in aqueous and serum in normal and mature cataractous Indian patients. Indian J Ophthalmol [serial online] 1963 [cited 2020 Mar 31];11:58-61. Available from: http://www.ijo.in/text.asp?1963/11/3/58/38883

Table 2

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Table 2

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Table 1

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Table 1

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All workers agree that the ascorbic acid concentration in aqueous humour is appreciably higher than that in serum. But how far is the lens responsible for maintaining this higher concentration of ascorbic acid in aqueous humour is still disputed. Various workers have estimated the aqueous humour concentration of ascorbic acid in normal, cataractous and aphakic cases with different results. Reduced concentration of ascorbic acid in aqueous humour have been observed in patients with senile cataract (Muller and Busche, 1934) in eyes of animals with experimental cataract (Nakamura and Nakamura, 1935) and in eyes of rabbits from which lens have been removed (Bietti, 1935), supporting the view that the lens is responsible for the maintenance of a higher concentration of ascorbic acid in aqueous humour. Percell et al (1954) and Chatterjee and Ghosh (1956) have on the other hand reported that there is no appreciable difference in aqueous humour/serum ratio of ascorbic acid in normal, cataractous and aphakic cases showing thereby the lens is not responsible for the higher concentration of ascorbic acid in aqueous humour. The number of cases with normal lens reported by these workers were small. Secondly the cataractous cases included in their series, although sufficiently opaque to warrant extraction were not uniformly opaque and were of various types. Lens although sufficiently opaque to warrant extraction can be opaque to different degree and may be in different state of metabolism, thus producing variations in the concentration of ascorbic acid in aqueous humour. On the other hand, as all organs of the body have a sufficient amount of reserve power in their function, it is possible that a partially opaque lens can still be responsible for maintaining a normal concentration of ascorbic acid in aqueous humour. Therefore in the present series, a large number of cases with normal lens has been taken and all the cases with cataractous lens were fully mature and totally opaque to make the assessment more accurate.


  Selection of Patients Top


Estimation of ascorbic acid in aqueous humour and serum was done in 1o cases having normal lens and in 1o cases of fully mature cataract. The cases with lens were selected from patients who attended the Ophthalmic Department of J. A. Group of Hospitals for minor extra ocular operations. The cases with mature cataract were selected from the patients who were admitted in the hospital for extraction of lens. The subjects chosen for the study did not have any intraocular inflammation. Malnourished and undernourished subjects were not included. All the cases of mature cataract were examined by the slit-lamp with dilated pupils to confirm that the lens was totally opaque.


  Methods Top


Under strictly aseptic conditions, aqueous was withdrawn in a dry tuberculin syringe with a No. 26 hypodermic needle. The fluid was measured and immediately transferred into a dry centrifuge tube. Immediately afterwards blood was collected aseptically from the antecubital vein and was transferred to a centrifuge tube and allowed to clot.


  Estimation of ascorbic acid Top


Ascorbic acid was estimated in the aqueous humour and serum by the method of Lowry, Lopez and Bessey (1945). To the total amount of aqueous humour collected and to 0.5 c.c. of serum obtained after centrifuging the clotted blood, 2 c.c. Of 5% trichloroacetic acid was added and mixed separately. The two tubes were then centrifuged for 10 minutes at 3000 r.p.m. and 1.5 c.c. of supernate from each tube was transferred to two other tubes. In a third tube 1.5 c.c. of a standard solution of ascorbic acid was taken, which was prepared by mixing ro c.c. of 1 mg. % solution of ascorbic acid with 40 c.c. of 5% trichloroacetic acid in a 50 c.c. volumetric flask.

Now to each of the three tubes containing the aqueous humour, serum and the standard ascorbic acid solution, 0.5 c.c. of dinitrophenyl hydrazine thiureacoppersulphate reagent was added and mixed thoroughly and then placed in an incubator at 37C for four hours. The tubes were then removed and chilled in iced water. 2.5 c.c. of ice cold 65% sulphuric acid was then added to each of the tubes and the contents mixed thoroughly and allowed to stand for thirty minutes at room temperature. The colour developed was read in a Galen Ramp photoelectric colorimeter with filter 520 mu and compared with the standard solution of ascorbic acid, the colorimeter being set initially at o with a blank prepared in the following way:

1.5 c.c. of 5% trichloroacetic acid and 0.5 c.c. of dinitrophenyl hydrazine thiureacoppersulphate reagent were mixed in a test tube and to it 2.5 c.c. of ice cold 65% sulphuric acid was added and mixed.

In calculating the ascorbic acid concentration in aqueous humour the figures were multiplied by the dilution factor of each case


  Results Top


The results obtained in normal and mature cataractous cases are given in [Table - 1] and [Table - 2] respectively.

They show a fairly uniform concentration of ascorbic acid in aqueous and serum in both normal and mature cataractous cases, there being no wide variations. The average concentration of ascorbic acid in aqueous humour of both the normal and mature cataract patients being practically the same the average ratio of its concentration in aqueous humour to that in serum is also almost equal. There is also a close relationship between the concentration of ascorbic acid in serum to that in aqueous in almost all the cases, the concentration of ascorbic acid in aqueous humour varying generally with the concentration of ascorbic acid in serum. Those cases showing a higher concentration of ascorbic acid in serum also show a high concentration of ascorbic acid generally speaking, in aqueous humour and vice versa.


  Discussion Top


The present work on 10 cases with normal lens and 10 cases with mature cataract confirms the findings of all previous workers that the concentration of ascorbic acid in aqueous humour is appreciably higher than that in serum. In our series the ratio of ascorbic acid concentration in the aqueous humour to that in serum in cases with normal lens is more or less the same as in cases with mature cataract. This finding is in agreement with that of Purcell et al (1954) and Chatterjee and Ghosh (1956). On the basis of these findings it can be stated with a fair degree of certainty that cataract formation does not alter the maintenance of a high concentration of ascorbic acid in the aqueous humour, either by synthesis or any other means. Therefore the explanation that it is the secretion of ascorbic acid by the ciliary epithelium which is responsible for the high concentration of ascorbic acid probably holds good. A further confirmation by a similar assay in eyes in which cataract has been removed intracapsularly should clinch the view.

Our results also confirm the findings of Purcell et al (1954) and Chatterjee and Ghosh (1956) that the ascorbic acid concentration in aqueous humour varies with that in serum. Although the concentration of ascorbic acid in aqueous humour and serum in both normal and mature cataract cases in the present series is fairly uniform, the finding that the concentration of ascorbic acid in aqueous humour varies with the concentration in serum sets a limit to the significance of any absolute value of ascorbic acid concentration in aqueous humour in any individual case, unless the concentration in serum has also been estimated at the same time. Purcell et al (1954) have rightly stated that "it is the knowledge of the ratio of concentration of ascorbic acid in aqueous to that in serum which is important". The findings of earlier workers who have reported a lower concentration of ascorbic acid in aqueous humour in cataractous and aphakic cases without determining the concentration of ascorbic acid in serum at the same time is therefore of less significance as in these patients the serum concentration itself might have been low.

The values obtained in the present series show a uniformly low aqueous/ serum ratio of ascorbic acid corroborates the findings of Chatterjee and Ghosh (1956) that in Indians the ratio of ascorbic acid in aqueous to that in serum is appreciably low. It is just possible that it is the existence of this relatively low ascorbic acid concentration in the aqueous and serum maintained in a chronic form over a long period which may be responsible for the high incidence of senile cataract in Indians and that too occurring at a relatively earlier age. Whether it is the higher pigment content of the ciliary epithelium in Indians exercising a retarding effect on the secretion of ascorbic acid as suggested by Chatterjee and Ghosh (1956), or some factor responsible for this low ratio we are unable to say.


  Summary and Conclusions Top


The finding of almost the same aqueous/serum ratio of ascorbic acid concentration in 10 normal and 10 mature cataract cases reduces the possibility of lens being responsible to any appreciable degree for the maintenance of a higher concentration of ascorbic acid in aqueous humour. A similar result in aphakie eyes would completely rule out such a possibility. The close relationship between the concentration of ascorbic acid in serum and aqueous humour points to the importance of estimating the concentration of ascorbic acid in serum at the time. It is suggested that it may be the existence of a relatively low ascorbic acid content of aqueous and serum maintained in a chronic form over a long period in Indians which may be the cause of the high incidence of senile cataract.[6]

 
  References Top

1.
Bietti, G., (1935), Boll. Ocul. 14, 3.   Back to cited text no. 1
    
2.
Chatterjee, B. M. Ghosh, B. P (1956), A.M.A. Arch. Ophth. 56, 756-760..  Back to cited text no. 2
    
3.
Lowry, O. H. Lopez, J. A., and Bassey, (1945), J. Biol. Chem. 160, 690.  Back to cited text no. 3
    
4.
Muller, H. K., and Buschke, W. (1934) Arch., Augenh. 108, 368.  Back to cited text no. 4
    
5.
Nakamura, B., and Nakamura, O. (1935), von Gracfes Arch. Ophth. 134, 197.  Back to cited text no. 5
    
6.
Purcell, E. F., Lerner, L. H., Kinsey, V.E. (1954), A.M.A. Arch. Ophth. 51, 1-6.  Back to cited text no. 6
    



 
 
    Tables

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