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ARTICLE
Year : 1969  |  Volume : 17  |  Issue : 1  |  Page : 33-36

Effect of sutures on corneal curvatures after cataract extraction


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

Date of Web Publication4-Jan-2008

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 V K. Effect of sutures on corneal curvatures after cataract extraction. Indian J Ophthalmol 1969;17:33-6

How to cite this URL:
Singh Y P, Goel V K. Effect of sutures on corneal curvatures after cataract extraction. Indian J Ophthalmol [serial online] 1969 [cited 2020 Aug 9];17:33-6. Available from: http://www.ijo.in/text.asp?1969/17/1/33/37579

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 incision for cataract extraction is followed by changes in corneal curvature that result in astigmatism, with the meridian of greatest curvature perpendicular to the incision. After extraction a variable amount of astigmatism against the rule is produced during healing of the wound owing to the flattening of the cornea in the vertical meridian. The amount of astigmatism tends to diminish rapidly in the weeks following the operation when the healing of the section is completed. This astigmatism is variable and varies with different procedures of cataract extraction. If the resultant post operative astigmatism could be minimized better visual results may be obtained.

This study is an endeavour to establish the procedures of cataract extraction which result in the minimum amount of corneal astigmatism. With this aim in view we studied the effect of pre and post placed corneoscleral sutures and a conjunctival flap on post operative astigmatism following cataract extraction.


  Material And Method Top


The present study is based upon keratometric data of patients on whom the extraction of senile cataract was performed at the department of Ophthalmology, Sarojini Naidu Medical College, Agra by the members of the attending staff.

On admission, the corneal curvature and the refractive power of the cornea, together with the meridians of greatest and least corneal curvatures were measured by the help of a keratometer.

At the time of operation, the method of cataract extraction together with the type of incision and sutures used were recorded. Any operative complication that occurred during the operation was also noted. Four methods of suturing were evaluated [Table - 2]

On the 10th post-operative day, the corneal curvature and its refractive power were recorded.

On discharge, the patient was instructed to report for his final examination and aphakic correction at the end of two months, when the radii of corneal curvatures together with their refractive powers in the meridians of greatest and least curvature were again recorded.

Keratometric examination

By this we found the total refractive power of the eye in the various meridians, and the directions of the greatest and the least refractive meridian together with their radii of curvature.


  Observations Top


In this series, 100 cases were studied by the help of a keratometer and the readings recorded on three occasions: (1) pre-operatively, (2) on the 10th post-operative day and (3) in the eighth post operative week.

Out of 100 cases operated upon, intra capsular extraction was done in 73 cases and extra capsular in 27 cases. The incision in all cases was a limbal one. The technique of applying limbal sutures and the complications which occurred during operation are tabulated below, along with the resultant astigmatism. Whenever a conjunctival flap was raised, it was stitched back in position at the end of the operation.

On discharge of the patient from the hospital, generally on the tenth day the classical post operative against the rule" astigmatism was seen in all the cases both at the time of discharge from the hospital and in the eighth week post-operatively, which are tabulated in [Table - 2].

In [Table - 2] the average amount of change in astigmatism for each interval after operation is charted. In the event that the astigmatic error changed from with to against the rule, the arithmetical total of the two was used as the amount of change.

In this series of 100 cases studied 69 cases were found to have spherical corneal curvature pre-operatively, while 21 cases had a small amount of "with the rule" astigmatism and 10 cases had a small amount of "against the rule" astigmatism. This is in essential agreement with Stromberg's finding who states that at 50-80 years of age no astigmatism, or very weak corneal astigmatism with or against the rule is physiologically present.

The average preoperative radius of curvature of the anterior corneal surface was 7.54 mm and the average refractive power of cornea was 45.2 D. In 83 per cent of cases the directions of the axis of the primary and secondary meridians were 180 and 90 degrees respectively. These findings again are in full agreement with those of DONDER'S[4] BOURGEOS' AND TSCHERNINGS.[1].

These cases were all operated for cataract. On the tenth post operative day, the against the rule astigmatism found in all cases was in full agreement with findings of BUSSACA AND KAWAHARA[2], and GROENHOLM.This post operative against the vile" astigmatism is due to flattening in its vertical meridian due to weak apposition of the wound edges. The amount of this against the rule astigmatism on discharge of the patient from the hospital in different groups of cases as well as the average decrease in the refractive power in the vertical corneal meridian and the increase in refractive power in the horizontal meridian approximates the values of GROENHOLM.

The final post operative astigmatism following cataract extraction with the use of a conjunctival flap only and no sutures was not great (2.99 D), since accurately coapted wounds seal themselves promptly and the conjunctival flap aids in healing and securing the wound. The average values with the use of a limbal incision with a conjunctival flap and one preplaced corneoscleral suture was 1.80 D. HUGHES and OWENS (1.7 D), HILDING (1.50 D) and LEACH AND SUGAR (1.82 D) who used various types of sutures.

The average values of astigmatism in. the eighth post operative week with the use of two preplaced corneoscleral sutures was 1.28 D. This figure is less than the values of HUGHES AND OWENS' (1.4 D) HILDING' (1.50 D) who used two corneoscleral sutures in their series. When one post placed suture was used the average post-operative astigmatism was 2.30 D which is comparable to the findings of KIRBY.

The lesser amount of astigmatism and the relatively small changes in the axis of the primary and secondary meridians in the 8th week post operatively, with the use of preplaced corneoscleral sutures can be explained.

1. Preplaced sutures placed in a preformed groove, result in the correct coaptation of directly appositional points on the limbus.

2. Preplaced sutures go through exact and equal depths in the level of the edges of the wound.

This assures better approximation of radial appositional points of the section surfaces with the resultant lesser amount of astigmatism and change in axis.

With post placed sutures these points are ensured less and hence result in a comparatively greater amount of post operative astigmatism; and change in the axis of the primary and secondary meridians. This is so because of the corneal distortion produced during the process of healing, in which non-appositional points are made appositional and also because of over-riding -of the wound edges.

The manner of insertion of corneoscleral sutures has some significance. If the preplaced sutures are drawn too tight it may cause inversion of the edges of the wound. If the vertical limbs are not in radial direction they produce a lateral displacement which prevents accurate closure of the lips of the incision, and leads to a leaky wound and delayed healing. This in turn results in greater post operative astigmatism.

Thus we see the minimum amount of corneal astigmatism and corneal distortion, is produced by two preplaced corneoscleral sutures. Cases operated upon by this procedure will have better visual acuity since in aphakic patients the cornea is the chief refracting medium.


  Summary and Conclusions Top


This study was undertaken with a view to evaluate the changes in corneal meridians and the amount of astigmatism which follows suturing of the wound by various methods after cataract extraction.

1. A fairly uniform type of post operative recovery curve was seen to be present in 83 per cent of cases studied in each group. Those which showed marked variations from the normal, could, in most cases be explained by operative or post operative complications associated with poor healing of the incision.

2. All cases of operative or post operative complications result in a greater amount of final astigmatism, and greater change in the axis of the primary and secondary corneal meridians.

3. The use of sutures reduces the amount of post operative astigmatism.

Post placed corneoscleral sutures can easily be angulated or placed in non-corresponding points in the wound margins, thus accounting for a greater amount of post-operative astigmatism and even irregular astigmatism.

 
  References Top

1.
BOURCEO'S AND TSCHERNINGS: Extract Am. J. Oph. May, 1965.  Back to cited text no. 1
    
2.
BUSSACA, A. AND KAWAHARA: Cited by Flyod 12.  Back to cited text no. 2
    
3.
DONDERS: Accommodation and refraction of the Eye.  Back to cited text no. 3
    
4.
FI,YOD G.: Changes in corneas.  Back to cited text no. 4
    



 
 
    Tables

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