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   Table of Contents      
ARTICLE
Year : 1970  |  Volume : 18  |  Issue : 4  |  Page : 167-169

Scleral rigidity in emmetropes


Department of Ophthalmology, Sarojini Naidu Medical College, Agra, India

Correspondence Address:
Y P Singh
Department of Ophthalmology, Sarojini Naidu Medical College, Agra
India
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Source of Support: None, Conflict of Interest: None


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How to cite this article:
Singh Y P, Goel S K, Misra R N. Scleral rigidity in emmetropes. Indian J Ophthalmol 1970;18:167-9

How to cite this URL:
Singh Y P, Goel S K, Misra R N. Scleral rigidity in emmetropes. Indian J Ophthalmol [serial online] 1970 [cited 2019 Oct 18];18:167-9. Available from: http://www.ijo.in/text.asp?1970/18/4/167/35634

Table 2

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Table 2

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Table 1

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Table 1

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The problem of estimating intraocu­lar pressure in an undisturbed eye has been engaging the attention of the ophthalmological world. Many a tono­meter was devised but all of them suffer from one defect, i.e. they disturb the equilibrium of the eye, when applied. This problem be-comes more accentuated when indentation tonometers are applied as they distort the eye-ball, strech their coats and expel the fluid out of the eye. Goldman's applanation tonometer can be said to be near per­fect as it is little affected by the rigidity of ocular coats. But when tonography is done the electronic tonometer pro­duces the changes comparable to in­dentation ronometer and hence the rigidity of ocular coats. But when tono­graphy is done the electronic tonometer produces the changes comparable to in­dentation tonometer and hence the rigi­dity of ocular coats play a significant part. This is a variable entity and is affected by the contents of the eye-ball, the stress and strain of the varying ten­sion and the structure of the sclera.


  Material and Methods Top


The study was conducted on normal patients who attended the out-patient department of S. N. Hospital, Agra, for various eye diseases like immature cataract, dacryocystitis, chalazion, stye and pteiygeum, etc. They had no in­traocular pathology. There was no history of glaucoma. The manifest error was not more than o.5 D.

The patient was asked to lie in a supine position and to fix the eye at a point on the ceiling. The eye was anaesthetised kith 1 % anaethaine drops. A certified Schiotz tonometer was brought in front of the visual axis and kept there for 3-4 seconds, to avoid oculocardiac reflex. The tonometer was then lowered on the cornea and rested for 2-3 seconds. Oscillation of the in­dicator on the scale were carefully observed and the whole or half scale unit close to the average position of pointer during the application was re­garded as the reading. The reading was repeated with a 10 gm. weight. The right eye was always examined first and the lighter weight preceded the heavier. The scleral rigidity was calculated by using the table of Becker and Schaffer. The case was again examined the next day and if any discrepancy was found the case was excluded.


  Observation Top


A total number of 395 eyes of 216 normal individuals of which 211 male and 184 eyes of 104 females were examined. Both the eyes were examined except in one-eyed patients. The cases were divided into four age groups be­tween 20-30 years, 30-40 years, 40-50 years and above 50 years [Table - 1]

[Table - 2] shows the distribution of scleral rigidity in each of the four groups.

[Figure - 1]. Graph : Showing average scleral rigidity in different age groups.

[Figure - 2]. Scatterogram : Showing dis­tribution of scleral rigidity in various age groups.


  Discussion Top


More than a century ago, Von Gaefe designed the first indentation tono­meter, to be followed by the applana­tion tonometer developed by Weber[6] (1888), the pendulum has been going back and forth. Schiotz[5] deve­loped the tonometer which bears his name and realising its shortcomings calibrated it thrice in a span of 10 years.

Friedenwald[2] postulated coefficient of scleral rigidity to be a constant characteristic of the eye of an in­dividual. This has been questioned by Perkins and Glocter[4], Grant and Trotter[3].

The Schiotz tonometer is calibrated for a rigidity of .0215 and any varia­tion in the value of scleral rigidity will give erroneous readings.

In our cases the average rigidity was found to be .0227 in the patients between 20-40 years of age but statisti­cally insignificant. There was no dif­ference statistically between the two sexes and the two eyes of an individual. However, there was a definite increase of rigidity in patients over 5o years of age where the average rigidity was .0267, and this is statistically significant. This increase in rigidity can be attri­buted to the decrease in the elasticity of sclera as compared to that of the cornea after the age of 40 years. This could also be due to the loss of water and in increase of calcium in the tissue with age. This study brings out the necessity of estimating the scleral rigi­dity after 5o years of age as higher than normal rigidity will give higher values of intraocular pressure and the patient subjected to unnecessary medication and psychological trauma for the rest of his life.


  Summary and Conclusion Top


1. The normal scleral rigidity was found to be .0227.

2. There was an increase in scleral rigidity after the age of 40 years, but it was not statistically significant.

3. There was statistically significant increase in scleral rigidity after the age of 50 years.

 
  References Top

1.
Von Graefe: Tonometry & Tonography, Jhon. Gloster Page 2.  Back to cited text no. 1
    
2.
Friedenwald (1937): Am. J. Ophth. 30, 985.  Back to cited text no. 2
    
3.
Marc, F. J. (1957): Outflow pattern of Cat's eye. Amer. J. Ophth. 47: 547.  Back to cited text no. 3
    
4.
Perkins, E. S., Gloster, J. (1957): Further studies on the distensibility of the eye Brit J. Ophth..41: 475.  Back to cited text no. 4
    
5.
Schiotz, H. (1905): Arch Augnheilk 10: 1.  Back to cited text no. 5
    
6.
Weber, A. (1877): V. Graefes Arch. Ophth. 23: 1.  Back to cited text no. 6
    


    Figures

  [Figure - 1], [Figure - 2]
 
 
    Tables

  [Table - 1], [Table - 2]



 

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