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ARTICLE
Year : 1968  |  Volume : 16  |  Issue : 4  |  Page : 202-206

Radiation hazards to eyes in industry


Bombay, India

Date of Web Publication24-Dec-2007

Correspondence Address:
Y.K.C Pandit
Bombay
India
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Source of Support: None, Conflict of Interest: None


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How to cite this article:
Pandit Y. Radiation hazards to eyes in industry. Indian J Ophthalmol 1968;16:202-6

How to cite this URL:
Pandit Y. Radiation hazards to eyes in industry. Indian J Ophthalmol [serial online] 1968 [cited 2020 Aug 9];16:202-6. Available from: http://www.ijo.in/text.asp?1968/16/4/202/37555

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The post World War II era has made the public conscious about radiation hazards. The atomic bomb­ed areas of Hiroshima and Nagasaki have given material for thought, and the scientist today is trying to peep into the mysteries of radiation from different angles. Heister, 1739, was first to observe the effects of infrared radiation in glass blowers, whilst the radiation effect with X-Rays and Gamma rays upon the eyes was ob­served in the early roentgen era by Birch Hirschfeld in 1904. He also mentions the radiosensitivity of the eye of the fetus and the new born animals. Prior to this in 1897 Chalupechi first described the effect of ir­radiation on the eyes of rabbits. In 1907 Tribondean and Lafrague pro­duced irradiation cataracts. "Ioniz­ing radiation, tell nobody of their presence" says Professor Mayneord "and that rise of great industries de­pendent on the production of radio­active materials as their basic pro­cess necessarily introduces new ha­zards on a large scale, both to the individual worker and the general po­pulation." For the past two decades reports are published from all count­ries on the subject of radiation inju­ries. The study has been carried out from different angles like clinical study, histology and histobiology, mechanical changes, E.R.G., biochemical changes, study of the distance from the centre of radiation, animal ex­perimentation etc. In these particu­lar studies the eye has an important bearing in as much as (i) studies can be carried out on an isolated retina and (ii) the lens is an avascular cap­sulated stricture where repair to da­mage is hardly possible, and no out­side agency can take away the dam­aged tissue; (iii) it is more easily ac­cessible to study in more ways than one.

Our own clinical study has been carried out on glass blowers but for the rest of the material in absence of any specific studies in this direction it is purely 'Library research'. Be­fore we give the details of some ob­servations in experimental work we should like to place before you some clinical facts about the atomic radia­tion cataract.

Work, by Dodo suggests that inci­dence to cataract diminished sharply in radiations beyond 1600 metres from the hypocentre. He classifies these cataracts in four grades.

Cataract cases from irradiation seen at a radiation distance 900 metres from the hypocentre in 1957 and 1966 show no appreciable change, Masuda, 1966, has given some detailed records of his findings in 1101 suf­ferers. He feels that 96 or 8.7% have atomic cataract; 121 or 11% have sus­picious atomic cataracts. According to age the percentage is greater n people under 25 years 10.2% than over 26 yrs. 8.8%.

He gives the exposure distance as follows: with percentage;

Within 2 Km 79 cases (10.9%)

Within 2-3 Km 11 cases (4%)

Within 3-4 Km 3 cases (5%)

Within 4-5 Km 3 cases (7.5%)

Cataracts with signs and symptoms were seen in 68 cases or 11.3% and cataract without signs and symptoms was seen in 28 or 5.6%

He described the changes as fol­lows:

Granular atypical opacities 54%;

Disciform changes 27%;

vacuoles; plate like opacities, star figure opacities, in the rest.

Dosage of Radiation: There is some difference of opinion. Cogan for a distance of 1.97 Km places r-ray from atom bomb as 600r and neutron 3-15rep. Shone gives the neutron value as 280rep. This is the momen­tary dosage. A residual dose also occurs 100r during 100 hours. Hirose, gives the relation between incidence of the atom bomb cataract and doses of r-ray and neutrons. Between 0-49 radius 11.9% increases between 200 to 499 rad 55.3% and over 500 rad to 90%.

Tokunaga is of the opinion that the severity of the cataract is dependent on the dosage of the radiation. He and Hirose place visual disturbances in 5% of the cases.

Hirose, Tokunaga, and Inoda et al undertook slit lamp studies and described the following four groups:

(i) limit opacities;

(ii) Polychromatic posterior plaque opacities;

(iii) Roughness of posterior plaque opacities

(iv) thick opacities.

Histologically Dodo feels that the nests of granular fragments or broken down lens fibres are seen in the sub­capsular region. Tokunaga mentions the fibril dilatation of the posterior lens, ectopic cells in the posterior cap­sule and abnormal swelling of fibres. On electron microscopy he finds a dissociation parallel to lens fragments and an ectropion of the lens epithe­ioid cells leading to fibroblast cells and degeneration.

Having placed before you this brief clinical and histological outline, let us see what further interpretation and knowledge we can gain by experi­ment and research at the present day.

Most of the studies are with ioniz­ing radiation on animals, mammals, nocturnal moths, hen, frog, rabbit, brown moths etc. It comprises of a detailed study of the radiation strength, and the morphological, histological, chemical, biochemical, his­tobiological and ERG changes pro­duced by it. The modes of radiation employed are the X-Rays, beta Rays, and Neutrons.

Let us first consider the changes produced by irradiation on the lens. It is now common knowledge that microwaves, heat waves, ultraviolet light, and ionising irradiation can all produce cataracts. The radiogenic cataracts are symmetrical with a situa­tion at the posterior pole and appear as small radial opacities. The animals used for experiments are mostly rab­bits and rats. Von Sallmann et al 1955, Cogan et al 1953 Kandori 1956, Krause and Bond 1951 opine that there is no difference between the different types of ionising radiations used or the response to them in dif­ferent species of animals. Clinically the lens changes appear after a long latent period depending on the magni­tude of the dose, distance from the hypocentre, age of the animal and se­veral other factors. It also makes a difference if the whole or part of lens is irradiated. The younger the ani­mal the shorter is the period during which a change occurs and the chan­ges are most extensive. Histologically the lens epithelium shows changes in hours, days, months following radia­tion. Poppe 1942, Cogan and Do­naldson 1951; Von Sallmann 1955 found (i) a fall in the rate of mitosis in half an hour followed by cessation of mitosis for 2-6 hours; followed by excess of mitosis, fragmentation and later breakdown of the epithelium. If the lens is shielded in part and ir­radiated, results show that axial ir­radiation does not lead to opacity; ir­radiation of the whole lens leads to cataract; while irradiation of half of the lens gives rise to vacuole forma­tion in the area irradiated. A fairly common view exists that the cataract is the product, an indirect one, from the radiation effects of the ciliary body. Devik 1957, Pirie and Drance 1959 have shown that irradiation of the ciliary body leads to cataract for­mation. Kandori 1956, Pirie 1959 were unable to produce cataracts in pigeons and chickens.

Dosage: Experimental work by Rados; Schiz and Roberschneider sug­gests that the lens is the most radio­sensitive tissue. A single dose of 500 to 800 r. can cause cataract in man. X-Rays up to 100 to 1200 Kv are less penetrating and affect mostly the an­terior segment. More penetrating ra­diations affect the lens. Fractionation of X-Ray doses does show a cumula­tive effect. Beta radiation can produce cataract but a dose ten times as much is required through the centre of the cornea. Neutron radiations as shown in mice, rabbits and dogs are more effective than X-Rays, in producing cataracts. The threshold dose ac­cording to Upton et al is 150 rep for neutrons. Ham 1953 gives it as 45 rep for man. It varies with the ani­mal. Shiglo and Masuda 1955 have shown that in atomic radiations, in high dose exposures the cataract may appear several years after irradiation. Cyclotrons emit radiations of neutrons and r-rays. All cataracts in industrial workers are amongst the cyclotron operators. Hans-1953 gave a figure of 21. It should be remembered that fast neutrons from cyclotrons or from Po-B and thermal neutrons are 2-4 times as effective as 250KV X-Ray or 3-4 times as effective as 1-2 MeV r-rays.


  Biochemical changes Top


Histological: damage to nuclei occurs within half an hour of irradiation and staining is possible with desoxyribo­nucleic acid after a period of two weeks. Chemically there is decrease in the glutathione and this glutathione decrease continues as the lens be­comes opaque and then it is complet­ely destroyed.

Administration of cysteine, thiou­rea, glutathione, cystamine, before ir­radiation reduces the harmful effects of radiation. Cysteine is very effective in this condition and may act in one of the two possible ways. (a) by itself accepting the radiation thus reducing the amount of radiation to the lens and (b) it ability to prevent mitosis. (Sallmann, Swanson, Francois). The chemical changes observed are the re­duction in glutathione of the lens; a fall in the ascorbic acid in the aqu­eous; fall in enzyme glycoxalate, and acetaldehyde oxidase and reduction of desoxynucleic acid in the lens epi­thelium.

Cataract in the nuclear physicists: Abelson and Kougar (1949) reported cataracts in nuclear physicists. Ham in 1953 recorded 2 cases from those injured in nuclear explosions. This was caused by fast neutron and hard r-rays.


  Radiation effect on other tissues of the eye Top


a. Retina: Studies have been car­ried out on isolated retina and intact retina. It is observed that an isolated retina is injured more than intact re­tina by radiation.

Demirchoglyan et al 1965 studied the action of ionising radiation on the retina adopting the following, me­thods: i) use of contact lens and pro­longed flashes; ii) determination of ERG adaptation; iii) measurement of intraocular pressure; iv) determina­tion of blood components and v) the weight of the animals. They found in the early stages a radiation sick­ness, with increased fluctuation in the ERG; a tendency to leukopaenia, disturbances of higher nerve reflex activity, and later cataract. Increase in radiation causes minor changes in photo-receptors but the nerve fibres of the ganglion cells are least affect­ed. It is apparent that a phenome­non of radio-phospherence occurs in the retina and the scotopic areas are much more affected, the rods are ge­nerally affected. Marmur and Man­turo 1966 state that the vulnerability of the retina to radiation is disputed in view of two reasons (i) retinal membrane is considerably radio re­sistant, (ii) retinal membrane has high sensitivity. Using six months old chinchilla rabbits weighing 1500 to 1700 kg they gave single X-radiation of 1 KR; 5 KR; 10 KR to different batches and studied the histopatho­logy at different intervals after irra­diation. In the first case of 1 KR they obtained focal damage in the nuclear layer with a partial penetration of the rod layer, a decreased staining of cells and hyperchromatolysis of the gang­lion layer. The whole thing suggest­ed a mosaic pattern. There appear­ed some signs of reversibility. With 5 KR within 1 to 3 hours there was focal damage in the outer molecular layer, reduced staining of the gang­lion cells, and hyperchromatosis of the inner nuclear layer. These chan­ges were more substantial on the 5th day, with fine granular breakdown of the rod and cone laver. With 10 KR, substantial pathological changes are seen on the tenth day. These are a breakdown of the rod and cone la­yer, death of inner and outer mole­cular layer, loss of histological struc­ture of large ganglion cells and exfo­liation of the retinal membrane. Peps has shown that rhodopsin is decolo­rised by heavy doses of roentgen.

The Choroid: M. Perreres; Taylor; D. Brinkley, Tegwedd Reynolds; (1965) discuss choroidoretinal chan­ges as complications of radiotherapy. They have recorded their minute ob­servations on patients undergoing ra­diation treatment near the eye for a period of 14 years. The changes found in 24 persons out of 119 are punctate keratitis, atrophy of the iris, glaucoma, cataract; The changes ob­served in the posterior segment are i. temporary choroidal pallor, with constriction of the retinal vessels, ii. atrophy of the choroid and retina with pigment at the edge, iii. acute choroiditis with fluffy edge iv. retinal changes simulating hypertension retinopathy.

ERG studies have been carried out on the irradiated retina and show a -ve a wave; a positive b wave; a con­tinuous positive c wave; and when stimulus ceases a d wave.

ERG shows an effect on the func­tioning of the eye in low dosage. ERG is suppressed with 3000r.

In mallow moth the ERG may show a weak recording or may be absent. Other effects: Roentgen and gamma radiation affect all parts of the eyes. It leads to necrosis of the lid cartil­age, suppression of lacrymal secre­tion; telengiectasis of the conjunctiva; lack of lustre of the cornea and growth of vessels and ulceration.

The Visual pathway: We have co­vered the receptors, we must now consider the conducting paths. Experi­mentally it is found that receptor out­put to C.N.S. can be altered by ir­radiation. If a-particles are placed on the cats tract, first there is en­hancement and later loss of conduc­tion. 400 to 1200 r radiations to rab­bits' head lead to alterations of ERG records from the lateral geniculate body and the visual cortex in respon­se to flashes of light. In hens, radia­tion of the head leads to "Opticogenic catalapsy".

There is loss of visual sensibility as a descrimination in visual behaviour. This is more of the scotopic type.

In conclusion I may say that the work on irradiation has something interesting and as industrial growth is one of the main aims in the country today, some of the younger generation should take interest in it and the Council for prevention of blindness should make necessary facilities avail­able for this important research.

I wish to convey my sincere Thanks to Atomic Energy Establishment, Trombay, for their kindness in pro­viding and allowing me the use of the literature.



 
 
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