ARTICLES
Year : 1983 | Volume
: 31 | Issue : 7 | Page : 816--822
"Role of zinc (Yashad Bhasma) in arrest of myopia"
RN Puri, V Thakur, HV Nema
Department of Ophthalmology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
Correspondence Address:
H V Nema
Department of Ophthalmology, Institute of Medical Sciences, B.H.U. Varanasi-221 005
India
How to cite this article:
Puri R N, Thakur V, Nema H V. "Role of zinc (Yashad Bhasma) in arrest of myopia".Indian J Ophthalmol 1983;31:816-822
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Puri R N, Thakur V, Nema H V. "Role of zinc (Yashad Bhasma) in arrest of myopia". Indian J Ophthalmol [serial online] 1983 [cited 2023 Jun 10 ];31:816-822
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Full Text
INTRODUCTION
The importance of trace elements in the body was realised only recently. Zinc is one of the most extensively investigated and best understood of the metabolically important trace mineral micronutrients.
Although zinc had been known to be essential to the growth of micro-organisms for over hundred years, it was not until 1934 that zinc was shown to be necessary for growth and well being of the rat[1],[2]. sub In 1961 it was first suspected that zinc deficiency may occur in man-, which was confirmed in 1968.[4],[5],[6] In studies from Iran[7], it was clearly demon�strated that zinc is a principal limiting factor in the nutrition of children and adolescents and this probably accounted for growth retar�dation so commonly seen there.
Investigations by a large number of authors[8],[9],[10],[11] showed that there is disturbances in mineral, albuminous and fat metabolism in people suffering from myopia.
Recently it has been claimed that an indegenous medicine "YASHAD BI-IASMA" (which contains zinc compound) can arrest the progress of myopia[12]. Considering the high prevalence of myopia specially in child�hood and adolescence it was thought worthwhile to asses the efficacy of the drug on controlled myopic patients.
MATERIAL AND METHODS
A double blind control study was conduc�ted in the Department of Ophthalmology, Institute of Medical Sciences, Banaras Hindu University, Varanasi. Ninty (90) myopic individuals were selected. They were divided into two groups consisting of 60 test and 30 control. Each case was subjected for detailed ocular examination including keratometery, retinoscopy (under cycloplegic), slit lamp examination and funduscopy.
Initial serum zinc level was estimated by atomic absorption spectrophotometer. All the 60 myopic cases (test group) received the zinc compound capsul (containing 250 mg of Yashad Bhisma) twice daily for 2 months before meal, while the control group received placebo (calcium lactate) with same drug schedule of administration. All the cases were followed up at 2 months interval. A repeat retinoscopy and serum zinc level estimation were done after completion of the drug schedule (2 months). Only those cases were considered who received a total of 30 gms of the compound. 20 cases from the test group and 10 cases of the control group were excluded from the study, since they could not complete the drug schedule properly. The retinoscopic findings and serum zinc concen�tration before and after the drug were evaluated.
OBSERVATIONS
A double blind control study was carried out to asses the role of YASHAD BHASMA (Zn) on myopia.
The cases included in this study consist of 60 (sixty) test and 30 (thirty) control. On follow-up examination it was observed that only 40 of the former and 20 of the latter group had taken the treatment according to the drug schedule and reported for the recheck-up examination. The age of the cases ranged from 6 years to 35 years. The test group com�prised of 26 males and 14 females, while the control had I 1 males and 9 females. The age and sex distribution of the cases has been summarised in [Table 1].
The keratometric readings ranged from 7.20 mm to 8.35 mm in both test and control group. The keratometric readings of both test and control group are given in [Table 2].
Retractive status of the cases varied from -.25 D to -14.25 D. Distribution of the cases is shown in [Table 3].
Despite a wide range of progressive myopia included in our studies only 21 (35%) cases showed degenerative changes both in test and control group. Degenerative changes were present in 1 1 (27.5%) cases of the test and 10 (50%) cases of the control group respective�ly. In test group 2 (5%) cases showed wide�spread degenerative changes in the retina and vitreous and in 9 (22.5%) cases only temporal myopic cresent was present. In control group 2 (10%) cases revealed widespread degenera�tive changes in retina and vitreous and in 8 (40%) cases only temporal myopic cresent was present. No degenerative changes were found in 29 (62.5%) cases inn the test and 10 (50%) cases in the control group [Table 4]. Initial serum zinc concentration ranged from 0.59 ug/cc to 1.12 ug/cc with a mean value of 0.835 ug/cc.
On follow-up the keratometric examina�tion revealed that the drug has no effect over the curvature of the cornea, since the pre and post keratometric readings remained same [Table 2]. However, the drug showed both subjective and objective changes on refractive status of the cases. It is evident from [Table 5] that 17 (42.5%) cases showed improvement in the visual acuity of the test but there was no improvement in control group. The subjective changes were further confirmed in-terms of dioptric power. 8 (20%) males and 6 females showed decrease in dioptric power but no increase was oberved. 26 (65%o) cases (both male and female) the power remained stationary. The subjective change in dioptric power found in control group indicates that the myopia increased in 2 (10%) of the males and 3 (15%) of the female patients but dec�rease in power was observed in none of the cases. However, power in 15 (75%) cases remained unchanged. Objectively these fin�dings were confirmed (Talbe 5). The serum zinc level ranged from 0.760 ug/cc to 1.36 ug/ cc with a mean of 0.997 ug/cc.
DISCUSSION
The biological importance of zinc stems primarily from its role in many vital enzyme systems. Moreover, zinc appears to have a role in nucleic acid metabolism and protein synthesis[13],[14],[15],[16],[17]. Zinc has a fundamental role and importance in early infant development and growth [18] , sub tissue regeneration[19] and in the stabilization of biological membranes. Further evidence of the biological impor�tance of this metal is brought forth by the recent reviews of aspects of zinc meta�bolism[20],[21],[23].
The zinc content of a normal 70 kg male is approximately 1.5 to 2.0 gms. Liver, kidney, bone, retina, prostate and muscle appear tote rich in zinc[24]. It is also known that zinc is pre�sent in high concentration in the choroid[14],[17] and paly a role in pigment formation[14]. Recently it has been shown that prostaglan�din E, not only binds zinc, but also facilitates its transfer across the intestinal mucosa in the rat [24] .
Follis, Day and McCollum[25] (1941) des�cribed corneal vascularisation without kera�tinization in 2 out of 7 rats which were fed on a diet supplying only 2 to 4 micro-grams per rat per day of zinc. Nishimura[26] (1953) reported changes in the eyelids and conjunctiva insuckling mice who were deprived of colostrum. Micro-ophthalmos was among the many deformities produced in chick embryos of hens on a ration deficient in zinc[27] (Blamburg et al., 1960).
Weitzel et al (1954) showed a marked cor�relation between the structure of choroid, tapetum, and retina and zinc concentrations among mammals. Those with low zinc levels in choroid had a fibrous tapetum while those with high zinc concentrations had a cellular tapetum. Budinger[29] (1961) after injecting IN. doses of chelating agent diphenyl thiocar�bazone (dithizone) found gross loss of zinc from the tapetum with secondary retinal detachment and permanent blindness.
Pandey[30] (1979) revealed that zinc has role in vision by activating probably a zinc enzyme retinal reductase which is respons�ible for the conversion of Vit. A to retinene.
Ketola[13] (1979) in his studies on rainbow trouts found that cataract developed in those who were fed on meal without mineral sup�plementation. Cataracts were prevented, however, with supplementation of zinc but not by supplementaion of maganese, copper, iron or various other minerals.
It is not easy to adequately asses zinc status in man. Zinc levels in plasma, RBCS, hair, saliva, amniotic fluid and urine, have been measured in the past[32],[15],33],[34],35],[17].We have assessed the zinc status by measuring the serum zinc level.' At present, the critical test for zinc deficiency in man or animals is a definitive clinical response to zinc sup�plementation under controlled conditions[14].
We have assessed the serum zinc status of our myopic patients and found that serum zinc levels were on the lower side of the nor�mal zinc level. The values ranged from 0.59 micro-gram/cc to 1.12 micro-gram/cc with a mean of 0.835 micro-gram/cc. initially. On contrary Silverstone[36]' (1981) found higher plasma zinc levels in cases of high myopia. His values ranged from 79 micro-gram/100 ml. to 177 micro-gram/100 ml with an average of 121 micro-gram/100 ml. The normal plasma zinc level is quoted to be 121 micro�gram/100 ml (Sandstcad, H.H.. 1973) and serum contains 16% more zinc than in the plasma[37].
The refractive status of 40 myopic cases (test group) before therapy varied from -0.25 D to more than -6.00 D [Table 3]. After therapy, though the zinc level increased significantly the refractive status did not change statistically. Prolonred use (2 months) of the drug in our study produced both subjec-tive and objective improvements in myopes but it was not statistically significant. A few of our cases showed subjective and objective improvement in the vision, this change might have occurred due to improved metabolic activity of the ocular lens owing to stimulated enzyme activities by zinc compound.
However, we do not have any experimental or biochemical evidences to substantiate this observation. The data on our record however do not show the beneficial effect of zinc com�pound in myopia.
SUMMARY
This study was conducted to assess the beneficial role of zinc on 40 cases of myopia. Though there were subjective improvement, but objective improvement was not statis�tically significant.
ACKNOWLEDGEMENT
We are grateful to I.C.M.R., New Delhi, under the auspecies of which this study was undertaken.
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