|Year : 1988 | Volume
| Issue : 1 | Page : 4-6
Cation and water transport during maturation of cortical cataract
AK Khurana, Harbans Lal, AS Saini, BS Chauhan, BK Walia
A K Khurana
Source of Support: None, Conflict of Interest: None
Water, electrolyte and free amino acid content of the crystalline lens were estimated in patients with nuclear cataract and in immature, mature and hypermature cortical cataract groups. Wet weight/dry weight and sodium/potassium ratios were calculated. Sodium, potassium ratio was significantly higher in immature cortical cataract when compared with the nuclear cataract. With maturation of the cortical cataract, the lens was found to be more hydrated and there was accumulation of sodium. However, free amino acid content of the lens decreased. A hypothesis has been proposed for alterations in the active transport pump of the crystalline lens during the maturation of the cortical cataract.
|How to cite this article:|
Khurana A K, Lal H, Saini A S, Chauhan B S, Walia B K. Cation and water transport during maturation of cortical cataract. Indian J Ophthalmol 1988;36:4-6
|How to cite this URL:|
Khurana A K, Lal H, Saini A S, Chauhan B S, Walia B K. Cation and water transport during maturation of cortical cataract. Indian J Ophthalmol [serial online] 1988 [cited 2020 Apr 5];36:4-6. Available from: http://www.ijo.in/text.asp?1988/36/1/4/26163
| Introduction|| |
The crystalline lens is the least hydrated organ of the body, the cortex being comparatively more hydrated than the nucleus. The lens maintains this state of hydration by an active cation pump that resides within the membrane of the cell, in the lens epithelium and in each lens fibre . Due to the presence of this active transport system the lens behaves like a single cell extruding sodium It also actively transports amino acids which are primarily used for the synthesis of lens proteins . With maturation of the cortical cataract water content, wet weight and sodium concentration of the crystalline lens have been shown to be significantly increased, while, protein free amino acid and potassium levels were decreased ,, In the present study it was proposed to examine a hypothesis regarding the alterations in active transport system of the lens, during maturation of the cortical cataract
| Materials and Methods|| |
Fortyseven patients (23 males and 24 females), in the age group of 50-80 years, presenting in different stages in the maturation of a cortical cataract were investigated Patients were divided into 3 groups, i.e. immature cortical cataract (16 patients; 8 males and 8 females); mature cortical cataract (16 patients; 9 males and 7 females) and hypermature cortical cataract - Morgagnian type (15 patients; 6 males and 9 females). For this comparative study a group of 14 age matched patients (8 males and 6 females) with nuclear senile cataract were studied and the results were compared with the group of patients having immature cortical cataract Further the results for the various observations during the different stages of maturation have been compared with one another and also with those of a nuclear cataract
The cataract was removed intracapsularly. The lens was weighed and homogenised with 10 volumes of trichloracetic acid (10% W/ V) at 4 o C, using a Potter Elvehjem homogeniser fitted with a teflon pestle. The homogenate was centrifuged at 5000 x g for 15 minutes and the supernatant was used for electrolyte and free amino acid estimation
Electrolytes were estimated using a Flams photometer (Gallen Kemp, U.S.A.). Free amino acid content was estimated according to the principle of Goodwin . To calculate the amount of lens water, the wet weight of the tissue was taken, the tissue was dried to a constant weight and the dry weight of the tissue was noted
| Observations|| |
Water content and wet weight/dry weight ratio of the crystalline lens for the immature cortical cataract group were higher when compared with the nuclear cataract however, the differences were not statistically significant cant (p > 0.05) The values were significantly increased with the maturation of a cortical cataract [Table - 1].
Electrolytes and free amino acid content of the crystalline lens for the immature cortical cataract group were comparable with the group of nuclear cataract on comparing values during maturation of the cortical cataract it was noted that the mean value for electrolytes were significantly higher for the hypermature cortical cataract group (p < 0.05). However, free amino acid content of the lens was found to be significantly reduced with maturation of the cortical cataract [Table - 2].
Sodium/ potassium ratio was calculated to give an idea regarding the cation transport pump of the lens The ratio was found to be significantly higher for the group with immature cortical cataract when compared with the nuclear cataract Further the value was found to be significantly increased with maturation of the cortical cataract (p < 0.05; [Table - 2]).
| Discussion|| |
The observation of the present study suggested that immature cortical cataract differs from nuclear cataract with respect to the cation content of the crystalline lens since sodium/potassium ratio was significantly different in the two groups. However, water, electrolytes and free amino acid content were comparable in the immature cortical cataract and the nuclear cataract groups. The values were comparable with the range given for the normal lens by several workers ,,,
With maturation of the cortical cataract sodium/potassium and wet weight/ dry weight ratios were significantly increased while free amino acid content was decreased For the group with hypermature cortical cataract (Morgagnian type), water and electrolyte contents and wet weight/dry weight and sodium/ potassium ratios were significantly higher as compared with the other 3 groups. Maraini and Mongili  reported that even in the early stages of cortical cataract the mean sodium content of the lens is increased by nearly 3 fold as compared to the normal value. Further amino acid content of the lens was found to be significantly decreased with maturation of the cortical cataract The reduced levels of amino acids in the lens may lead to the decreased synthesis of lens proteins as suggested by several workers ,,
It is proposed that the altered cation levels of the lens during maturation of the cortical cataract maybe due to the changes in the cation transport pump which by active transport regulates the efflux of sodium and the influx of potassium [Figure - 1]. The water content of the lens being regulated by diffusion, allows the lens to act as an osmometer . Reduction of amino acid levels may also be due to alternations in the active transport pump as suggested by Reddy .
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[Figure - 1]
[Table - 1], [Table - 2]