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Year : 1985  |  Volume : 33  |  Issue : 2  |  Page : 91-94

Correlation between central corneal thickness and curvature


Dr Rajendra Prasad Centre for Ophthalmic Sciences, A.I.I.M.S., Ansari Nagar, New Delhi, India

Correspondence Address:
A Panda
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, A I.I.M.S., New Delhi-110029
India
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Source of Support: None, Conflict of Interest: None


PMID: 3833742

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How to cite this article:
Panda A, Venkateswarlu K, Angra S K, Kalra V K, Mohan M. Correlation between central corneal thickness and curvature. Indian J Ophthalmol 1985;33:91-4

How to cite this URL:
Panda A, Venkateswarlu K, Angra S K, Kalra V K, Mohan M. Correlation between central corneal thickness and curvature. Indian J Ophthalmol [serial online] 1985 [cited 2021 Jun 21];33:91-4. Available from: https://www.ijo.in/text.asp?1985/33/2/91/30828

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Table 4

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Table 3

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Table 2

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Table 2

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Table 1

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Table 1

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A significant correlation between corneal thickness and curvature are reported in the literature[1],[2],[3]. Most of the workers have failed to demonstrate significant correlation between central corneal thickness and curvature. How­ever, Hovding[4] has reported a weak correla­tion in these parameters, In this communica­tion we endeavoured to find out any existing correlation in our population.


  Materials and methods Top


200 eyes of 100 normal subjects, in the age group of 13-35 years were taken into the study. All the cases were randomly drawn from the out patient department with no refractive error. All the cases were subjected to the measurement of central corneal thick­ness and curvature Corneal thickness was measured with Goldman's pachometer No. I mounted on a Haag Streit 900 silt lamp. The correct corneal pachometer position was ensured by a method described by Stone[5]. The mean value of 3 measurements was recor­ded as the central corneal thickness.

The radius of curvature of the anterior central 3mm corneal surface was measured in two principal meridia using Javal-Schiotz keratometer. The mean values of 2 readings in each of the two meridians were recorded. Both the measurements (at the same sitting) were taken using the same instruments.


  Observations Top


The findings are as highlighted in [Table - 1][Table - 2] for right and left eye respectively. These parameters bear no significant difference bet­ween the two eyes. The values were compared with these in the literature [Table - 3]. The coefficient of correlation both for right and left eye are evident from [Table - 4]. No corre­lation exist between corneal thickness and curvature. [Table - 4], but a definite correlation exists between horizontal curvature and vertical and mean curvature [Table - 4],[Figure - 1].


  Discussion Top


The normal values of corneal thickness in healthy subjects as given in literature varies from 0.507 to 0.565[3],[6],[11]. As the same place was not assured in thickness measurement by pachometer, it was suggested by Mishima[6],[7],[12] that within this central 3 to 3.6 mm cornea the thickness is usually regarded as constant.

Several authors quoted varying values between these two figures. Our values of cor­neal thickness are slightly higher than the reported values from Western literature[2],[3],[6],[10]. The factors which contribute to the variation in measurement is individual end point varia­tion and different instruments and the techni­ques adopted. In this survey, the anterior surface of the epithelium of the lower section was aligned with the posterior surface of the endothelium of the upper section. This technique was adopted as it was felt that this represented the full thickness[1]. But this differs from the technique adopted by others who tried to align the whole of the epithelium with the whole of endothelium[7]. So when we of talk corneal thickness, it is always necessary to mention the instrument and the technique used for measurement. This might explain higher values in our study.

Our results show that there is no signifi­cant difference between the value in right and left eyes, 0.545 & 0.546 respectively, although earlier studies[2],[3] indicated that the left cornea is slightly thicker than the right cornea. The slight difference is said to be due to the angle Kappa [12],[13], causing a slight decentering of the measurement of corneal thickness. Almost all the studies conducted earlier on this subject have involved only the right eye[3],[7],[8],[9],[10],[11], except Kruse who found the thickness 0.004mm more in right eye than left[2]. How­ever, we have conducted the study in both eyes and did not find any significant difference in either eye.

In the earlier reports it has been reported that no correlation exists between central corneal thickness and central corneal curva­ture[3]. Our findings are in conformity with these reports. We found that there is definite correlation between horizontal and vertical curvatures of cornea.


  Summary Top


The study was conducted on both eyes of 100 healthy subjects. Central thickness and central curvature of all the eyes were measu­red. No correlation could be found between these parameters. The values were similar in both the eyes but definite correlation exists between various (horizontal & vertical) curvatures of cornea.

 
  References Top

1.
Tomlinson A., 1972, Acto Ophthalmol, 50: 78-82  Back to cited text no. 1
    
2.
Krause Hansen F,1971, Acta Ophthalmol 49 : 82-89   Back to cited text no. 2
    
3.
Lowe R., F., 1969, Brit J. Ophthalmol 53: 73-82,  Back to cited text no. 3
    
4.
Gunner Hovding, 1983, Acta Ophthalmol 61: 461-466  Back to cited text no. 4
    
5.
Stone J, 1974, Contact Lens Jour, 5 : 14-19  Back to cited text no. 5
    
6.
Mishima, S, and Hedbys, B, 0, 1968, Arch, Oph­thalmol (Chicago) 80 : 710-713  Back to cited text no. 6
    
7.
Maurice D, M, and Giardinic, A., A., 1951, Brit J. Ophthalmol 35 : 169.  Back to cited text no. 7
    
8.
Lavergne, G, and Kelcom, J., 1962, Bull. Soc. Balge. Ophthalmol 131 : 323-333.  Back to cited text no. 8
    
9.
Donaldson, D. D., 1966, Arch. Ophthalmol 76:25-31   Back to cited text no. 9
    
10.
Martola, E. L. and Baum, J. L., 1968, Arch. Of Ophthalmol 79 : 28-30.  Back to cited text no. 10
    
11.
Von Bahr, G., 1948, Acta. Ophthalmol 26 : 247-265   Back to cited text no. 11
    
12.
Mishima, S., 1968, Survey Ophthalmol 13: 57-96   Back to cited text no. 12
    
13.
Ehlers, N. and Krnsee Hansen. F., 1971, Acta.Ophthalmol 49 :65-81.  Back to cited text no. 13
    


    Figures

  [Figure - 1]
 
 
    Tables

  [Table - 1], [Table - 2], [Table - 3], [Table - 4]



 

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