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Journal of the Anatomical Society of India

Morphometric And Histological Study Of Human Cataract Lens

Author(s): Dorairaj, S.J; Vatsala, V; Vijaya Kumar, J; Kesavai R; Sucheethra, D.S; Vidyasree, S.

Vol. 51, No. 1 (2002-01 - 2002-06)

Department of Anatomy, SRMC & RI, Chennai - INDIA

Abstract

Cataract seems to be an ageing process. There are many precipitating factors such as diabetes, hypertension, prolonged exposure to sunlight etc. The enucleated cataract lens nucleus was studied in 100 patients. Detailed history, statistical data, morphometric study and histological picture of the selected cases were carried out. Of the cases observed, 53 were males and 47 were females. The age group ranged from 35 to 90 years. The etiology of cataract in 79 was due to senility; in 8 it was due to diabetes; in 7 it was due to hypertension; in 1 it was due to diabetes and hypertension and in 5 of them it was due to prolonged exposure to sunlight. The size of the nucleated cataract lens ranged from 0.7 to 0.9 cms. in diameter and 0.35 to 0.55 cms. In thickness and the colour ranged from cream, yellow, honey to brown. These lenses of differnt etiology were processed for H & E stain and they showed different histological pictures.

Key words: Human cataract lens, Morphometry, Microscopic appearance in Diabetes, Senility, Hypertension, Exposure to Sunlight.

Introduction:

The beauty of colour vision with a delight in true colour and form is an important part of human life with the eyes as the sole and unique window for its enjoyment. Yet ophthalmologists are faced everyday by limitation and fading powers of the sight organ. Cataract remains the leading cause of visual disability and blindness all over the globe. The problem is more acute in the developing countries. It is estimated that there are about 12 million blind people due to cataract in India alone. Cataract already a major cause of visual impairment and blindness is likely to become an increasing problem as the world population ages (Hales, et al 1997.)

For clinial ophthalmologists it would be interesting to learn, what histological changes correspond to the clinical features of cataract they find in various cataractous eyes in daily practice (Blumenthal et al 1991). It would also be useful for clinicians to exchange information and views on the clinical findings and corresponding histopathological features of cataracts, for it would lead to a better insight into cataracts and help them to make use of most of the latest knowledge in clinical practice. With this in mind, a detailed case history, statistical data, morphometric study and histological picture of the enucleated cataract lens were carried out.

Cataract is defined as visual impairment as a result of disturbances of lens transparency. The progressive sclerosing process within the lens is manifested at the end of fifth decade (Bertner, et al 1996).

The human lens changes in density and thickness correlating with aging (Kashima et al 1993). The degenerative process of lens fibres in a cataractous lens, is described as the biochemical changes of a part of the lens protein (Kalicharan, et al 1993).

When diabetes is not well-controlled, changes in blood glucose levels cause changes in sugar alcohols of the lens that in turn results in blurred vision (Vaughan, et al 1994).

Material And Methods:

One thousand free cataract operations with free intraocular lens implantation were organized and carried out by the Department of ophthalmology and visual sciences of Sri Ramachandra Medical College and Research Institute Porur, Chennai - and at that time the enuleated cataract lenses of 100 patients were collected along with a detailed case history.

  1. The statistical data of incidence of age, sex distribution and etiology were analysed.
  2. The enucleated lenses were collected from the operation theatre in small biopsy containers with 10% formal saline. The colour of the specimens was observed.
  3. The diameter of the lenses was measured in two differet directions with the help of dividers and the values were read from a scale and the average was taken. In the same way the thickness of the lens was also measured.
  4. The lenses of different etiology were selected and were processed for histological study by paraffin method and stained with haematoxylin and eosin.

Observations:

  1. Total number of patients operated for cataract - 100
    Male 53
    Female 47
  2. The age ranged from 35 to 90 years
  3. The probable etiology of cataract in these 100 patients is shown in Table 1.

TABLE 1 ETIOLOGY OF CATARACT

  Etiology No. of Cases
1. Senility 79
2. Diabetes 8
3. Hypertension 7
4. Diabetes & Hypertension 1
5 Prolonged exposure to Sunlight 5
  Total 100
  1. In the formal saline fixed lenses the colour ranged from cream, yellow, honey to brown.
  2. The lens of diabetic etiology always showed cream colour; hypertensive etiology showed yellow colour; and those of prolonged exposure to sunlight showed honey colour and due to senility showed different colours from cream, yellow, honey to brown, as age advances.
  3. The diameter ranged from 0.7 to 0.9 cms. with a mean value of 0.85 ± 0.15 cms.
  4. The thickness ranged from 0.35 to 0.55 cms with the mean value of 0.45 ± 0.1 cms
  5. The minimum and maximum values of diameter and thickness in different age groups showed a definite increase in diameter and thickness as age advanced.

Histological findings:

Lens of diabetic etiology showed lamellated bands of lens fibres of different density.

Lens of hypertensive etiology showed homogenous areas and certain areas of fine lamellations scattered with fine spaces.

Lens of persons with prolonged period of exposure to sunlight showed homogenous area. Senile cataract lens of

  • cream colour showed fine lamellations
  • yellow colour showed well defined lamellations
  • honey colour showed very well defined lamellations
  • brown colour showed - dense & homogenous areas and because of the difficulty in cutting showed lot of serrations.

Discussion:

There was a strong positive correlation between increasing age and the density of the lens (Kashima, et al 1993) According to the present study, as seen in the Table 2, there is a strong positive correlation between increasing age and diameter and thickness of enuleated lens.

Table 2: Correlation of Age with Diameter and Thickness of lens

  Diameter Thickness
Age Group
In Years
Minimum
in Cms.
Maximum
in Cms.
Minimum
in Cms.
Maximum
in Cms.
35 - 39 0.45 0.8 0.3 0.4
40 - 49 0.5 0.9 0.35 0.35
50 - 59 0.7 0.9 0.3 0.5
60 - 69 0.7 0.9 0.35 0.5
70 - 79 0.8 0.9 0.4 0.5
80 - 89 0.8 0.9 0.45 0.5
³ 90 0.8 0.9 0.45 0.5

Statistical analysis revealed positive correlation between central thickness and age (p < 0.05). There was a weak positive correlation between central thickness and hardness of the lens (Ayaki, et al 1993). Post mortem study of human eye with the lens in situ showed a measurement approximately 4.5 mm. thickness and 9.5 mm diameter (Assia & Apple 1992). The present morphometric study of the enucleated cataract lens showed a mean value of 0.85 ± 0.15 cms. for diameter and a mean value of 0.45 ± 0.1 cms. for thickness, which were almost, close to that of the observations made by Assia & Apple (1992).

The dimensions of the lens are optically and clinically important, but they change with age as a consequence of continuous growth. Its equatorial diameter at birth is 6.5 mm, Increasing rapidly at first and then more slowly to 9.0 mm at 15, and even more gradually to reach 9.5 mm in the ninth decade. Its axial dimension increases from 3.5 - 4.0, in the ninth decade.

On measuring of the extracted central nucleus diameter and thickness of 88 eyes (average age of patiant 72 years) undergoing extracapsular cataract extraction, the average diameter was found to be

6.51 ± 0.75 mm. & the average thickness was 2.96 ± 0.33 mm. Since the average lens diameter is approximately 10 mm. A corneoscleral incision of 7 to 8 mm. in chord length should be sufficient for most extracapsular cataract extraction (ECCE) cases. Accumulation of these data & further analysis correlating them with age and degree and type of cataract in larger series will be useful in determining the smallest possible incision size required for individual patients (Ayaki et al 1993).

Diabetic cataract is the rapidly progressive one that is found in younger persons (under 40 years of age). There is no relationship between the duration and severity of diabetes and the onset and progress of the cataractous changes. However, as suggested by Vogt (1967) it could be provoked prematurely by diabetes. It is usually bilateral. When the diabetes is not well controlled, changes in blood glucose levels cause changes in refractive power by as much as 3 to 4 diopters. This results in blurred vision. Such changes do not occur when the disease is well controlled (Vaughan et al, 1994).

The well-defined lamellations of different density in diabetic cataract lens may be associated with varied glucose level. In general, the glucose concenteration In the aqueous, parallels the concenteration in the plasma (Kinoshita et al, 1961 and Kinoshita 1965).

The effect of hypertension on lens has not been reported. But in the present study, section of lenses of hypertensive etiology showed homogenous areas and fine lamellated areas dispersed with fine space.

Cataracts as a result of prolonged exposure to sunlight:

The cornea absorbs about 45% of light with wave lengths below 280 nm. Betwen 320 and 400 nm the cornea absorbs only 12%. Thus the unprotected lens is exposed to a considerable amount of long wave ultra violet light mainly from sunlight. Related to the sclerosis and nuclear opacification is the increased yellow discolouration of the deeper parts of the lens (this causes the yellow or honey colour). In at least one case Lerman, 1979 found a direct relationship between exposure to ultraviolet light and posterior subcapsular or cotrical lens opacities.

Senile Cataract:

As age advances there is a decrease in water content and more and more soluble protein becomes insoluble and the concentration of calcium increases. There is a progressive hardening of the lens, which is manifested after the age of 40. Some loss of transparency with age is inevitable. At least some degree of opacification in seen in 95% of persons over 65 years of age. Increased free amino acid levels in senile cataract indicate accelerated proteolysis (Barber 1968).

In Senile cataracts, the lens colour changes to dark yellow, then to yellow - brown and brown. Hardening of the lens nucleus parallels decreased transparency.

Vrensen et al, 1990 have observed three age related changes.

  1. ruptured membrane
  2. water vacuoles and
  3. multilamellar bodies

The frequency of these alterations increased with age. TEM studies show that the cytoplasm of some cataractous lenses appeared more granular in texture (Ghoul & Costello 1996). As per the present study it was observed that deepening of the colour took place with increased age as shown in the Table 3 and the lamellations became prominent as age advances.

Table 3 Senile Cataract

Colour of the lens No. of Cases Age Incidence (in years)
Cream 19 35 - 68
Yellow 28 49 - 72
Honey 25 50 - 78
Brown 7 55 - 90

The lens epithelium of the human eye plays a crucial role in the pathogenesis of primary and secondary cataract (Kohlmann & Lommatysch, 1995).

The lens damage and cataract formation appears to be due to in-situ generation of active radicals and other active species of oxygen. These oxygen derivatives may also contribute to the multifactorial process of senile cataract formation in human beings. This hypothesis is based on in vitro experiments with rat lenses (Varma & Richard 1988). The lens like other tissues possesses a number of mechanisms to protect itself against oxidation. The glutathione system, superoxide dismutase, catalase and glutathione peroxidase all play important roles.

An additional source of protection is ascorbic acid. Pyruvate is another agent useful in this regard.

Summary & Conclusion :

The enucleated cataract lenses of one hundred patients were studied. Detailed case history in the prescribed proforma, age incidence, sex distribution, morphometric study and histological study were carried out.

  • Cataract does not have predilection for sex.
  • Age ranged from 35 to 90 years.
  • The diameter of the lens was 0.85 ± 0.15 cms.
  • The thickness of the lens was 0.45 ± 0.1 cms.
  • The cataract lens of diabetic origin mostly had cream colour.
  • The cataract lens due to exposure to sunlight had yellow to honey colour.
  • In senile cataract the colour deepens as age increases and the brown cataract lenses are the most dense ones.
  • Lenses of different etiology showed different histological appearances.

References:

  1. Assia, E.I. & Apple, D.J. (1992) : Side - View analysis of the lens I the cystalline lens and the evacuated bag. Archives of Ophthalmology Jan 110 (1) : 89 - 93.
  2. Ayaki, M., Ohde, H. & Yokoyama, N; (1993): Size of the lens nucleus separated by hydrodissection. Ophthalmic Surgery; 24(7) : 492 - 3.
  3. Barber, G.W. (1968) : Free amino acids in senile cataractous lenses - possible osmotic etiology. Investive Ophthalmology 7 : 564.
  4. Berliner, M.D., Paul, B., & Hoeber, Inc. : Biomicroscopy of the Eye - In: Slit lamp microscopy of the living eye. 4th Edn. Volume II Medical book department of Harper and Brothers, Newyork, pp 1092-1093 (1997).
  5. Biumenthal, M., Assia, E., Neuman, D. (1991) : Lens anatomical principles and their technical implication in cataracts surgery Part II the lens nucleus. Journal of Cataract, Refractive Surgery Mar: 17(2) : 21-7.
  6. Ghoul, K.L. Costellow, M.J. (1996) : Fiber cell morphology and cytoplasmic texture in cataractous and normal human lens nuclei Current Eye Research ; 15(5) : 533 - 42.15(7) : 805.
  7. Hales, A.M., Chamberlain, C.G., Murphy, C.R. Mc Avoy, J.W. (1997) : Estrogen protects lenses against cataract induced by transforming growth factor - beta (TGF beta) Journal of Experimental Medicine. Jan 20; 185(2) : 273-80.
  8. Kalicharan. D., Jongebloed, E.L. : & Worst, J.G. (1993) : Lens fibre degeneration at Cataract lenses. ALM, SEM and TEM investigation Doc Ophthalmology, 85(1): 77 - 85.
  9. Kashima, K., Trus, B.L., Unser, M., Edwards, P.A., & Datiles, M.B. (1993) : Aging studies on normal lens using the Schermipflug Slit - lamp camera. Investive Ophthalmology Visual Sciences Jan : 34(1) : 262 - 99.
  10. Kinoshita, T.H., (1965): Cataracts in Galactosemia. Investive Opthalmology 4: 786.
  11. Kinoshita, J.A., Merola, L.A. Kern, H. (1961) : Factors affecting the cation transport of calf lens. Biochemistry Biophysics Acta 47: 458.
  12. Kohlman, H., Lommatysch, P.K. (1995) : Morphologic changes in the lens epithelium in patients with age- induced cataract, radiation and steroid cataract and cataract following eye contusion. Ophthalmologe Oct: 92(5). 741-4.
  13. Lerman, S. (1979): Ultraviolet radiation and human cataractogenesis. Investive Ophthalmology (Arvo, Suppl). p 128.
  14. Varma, S.D.: & Richard, R.D. (1988): Ascorbic acid and the eye lens. Ophthalmic Research. 20(3) : 164-73.
  15. Vaughan, D & Asbury, T. General Ophthalmology 10th End. : Lamage Medical publication, Los Atlas, California, p 247 (1994).
  16. Vogt (1967): Ocular pathology of diabetes mellitus. American Journal of Ophthalmology. 65: 21.
  17. Vrensen, G., Kappelholf, J. & Willekens, B. (1990) I Morphology of ageing human lens II Ultrastructure of clear lenses. Lebs Eye Toxic Research 7(1) : 1-30.
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