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ORIGINAL ARTICLE
Year : 2003  |  Volume : 51  |  Issue : 1  |  Page : 53-57

Keratometric astigmatism after ECCE in eastern Nepal. Continuous versus interrupted sutures.


Department of Ophthalmology, B P Koirala Institute of Health Sciences, Dharan, Nepal

Correspondence Address:
A Sood
Department of Ophthalmology, B P Koirala Institute of Health Sciences, Dharan
Nepal
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Source of Support: None, Conflict of Interest: None


PMID: 12701863

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  Abstract 

Purpose: The study aimed to compute and compare the keratometric astigmatism induced by wound closure with continuous and interrupted sutures in conventional extracapsular cataract extraction with intraocular lens implantation at a single centre in eastern Nepal.
Methods: Sixty eyes of 60 patients were included in the study. All patients received conventional extracapsular cataract extraction and single piece modified C-loop posterior chamber intraocular lens. Thirty eyes were sutured with continuous (Group 1) and 30 eyes with interrupted sutures (Group 2). The results were analysed by the unpaired student's t-test.
Results: At the end of 6 weeks, Group 1 patients had significantly higher astigmatism (3.53 2.19D) compared to Group 2 patients (1.7 1.35). A majority of patients in both groups had with-the-rule astigmatism throughout the postoperative period.
Conclusion: Interrupted sutures cause less astigmatism than continuous suture. The factors responsible for high astigmatism in continuous sutures call for further analysis.

Keywords: Cataract, keratometry, astigmatism, continuous sutures, interrupted sutures, Nepal


How to cite this article:
Sood A, Thakur SK, Kumar S, Badhu B. Keratometric astigmatism after ECCE in eastern Nepal. Continuous versus interrupted sutures. Indian J Ophthalmol 2003;51:53-7

How to cite this URL:
Sood A, Thakur SK, Kumar S, Badhu B. Keratometric astigmatism after ECCE in eastern Nepal. Continuous versus interrupted sutures. Indian J Ophthalmol [serial online] 2003 [cited 2020 Apr 10];51:53-7. Available from: http://www.ijo.in/text.asp?2003/51/1/53/14737



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Despite the trend towards small incision cataract surgery, a bulk of cataracts in developing countries like Nepal are operated by the age-old, time-tested conventional extracapsular cataract extraction (ECCE). The majority of surgeons are well versed in the technique and therefore prefer it to newer methods. This technique ensures optimal visual recovery for the patient, but high degrees of surgically induced astigmatism may limit the visual rehabilitation. The induced astigmatism is a reflection of the cataract incision and its closure.[1] The suturing technique is a major determinant of postoperative astigmatism.

The present study aimed to compute and compare the surgically induced corneal astigmatism in wound closure with continuous versus interrupted suturing in conventional ECCE performed in eastern Nepal.


  Materials and Methods Top


The study was undertaken in the Department of Ophthalmology, B.P. Koirala Institute of Health Sciences, Dharan, Nepal. Patients were selected based on the presence of uncomplicated age-related cataract. Patients with subluxated lens, traumatic cataract, co-existing glaucoma and uveitis were excluded.

Sixty eyes of 60 patients were included in this study. Patients were allocated alternatively to the two surgical procedures under study. Proper informed consent from patient/guardians was obtained. All the surgeries were performed by experienced consultants beyond the learning curve. Two of the authors performed continuous suturing (AS, BB) and two performed interrupted suturing (SK, SKDT).

All patients underwent conventional ECCE under peribulbar anaesthesia, A fornix-based conjunctival flap was raised. Bleeding points on the sclera were cauterised by bipolar thermal cautery. The size of incision at superior limbus was 8.5 mm in all the patients as measured by straight Castraviejo callipers. No clear corneal incisions were made. Anterior chamber depth was maintained with 2% methylcellulose. Envelope capsulotomy and in-the-bag posterior chamber intraocular lens (IOL) implant was done. In Group 1 (n=30 eyes) the incision was closed with 10-0 monofilament (nylon) continuous suture (single continuous, four cross) whereas in Group 2 (n=30 eyes) the incision was closed with five 10-0 monofilament (nylon) interrupted sutures. The depth of the suture bites was two-thirds the thickness of the cornea and sclera. The length of the bites was 2mm on either side in both groups.

Preoperative evaluation and follow-up was done by performing keratometry (Inami Ophthalmometer BL-1L-1050, Japan) and A-scan biometry (Nidek Echoscan) in all cases, apart from the routine investigations for intraocular surgery. All the patients had preoperative astigmatism of 2D or less.

Postoperative follow-up

This was done on the first day, first week, fourth week and sixth week. At each follow-up, the findings of keratometry, refraction, uncorrected and best corrected visual acuity were recorded. The results were statistically analysed by the unpaired students' t-test (two-tailed), Type 3. The amount of induced corneal astigmatism was calculated by the simple subtraction method, from the preoperative and postoperative keratometric readings.


  Results Top


The male:female ratio was 2:1 in both groups. Of the 30 patients in each group 20 were males and 10 were females. Most patients were in the 50-60 years age group [Figure - 1]. There was no statistically significant difference between the baseline variables in the two groups [Table - 1]. The mean preoperative astigmatism in Group 1 and Group 2 was 0.5 D and 0.6D respectively.

Immature senile cataract was seen in 19 (63.3%) patients in Group 1 and in 18 (60%) patients in Group 2. Mature senile cataract was seen in 7 (23.3%) patients in Group 1 and in 8 (26.6%) patients in Group 2. Four (13.3%) patients in each group had hypermature senile cataract.

The postoperative astigmatism on day 1 was 6.8 0.61D and 5.7 0.18 D respectively in Group 1 and Group 2 respectively. At one week postop, the astigmatism was 6.4 0.73D and 4.6 0.64 D respectively. The astigmatism reduced further to 4.3 0.52 D in the continuous group and 2.7 0.12 D in the interrupted group at 4 weeks. At the end of 6 weeks interrupted sutures induced astigmatism at 1.7 1.35, D, was significantly less (unpaired t test p < 0.01) than the continuous sutures induced astigmatism at 3.53 2.19 D [Figure - 2].

The pattern of astigmatism was with-the-rule (WTR) in 20 (66.7%) cases in Group 2 (interrupted) and 18 (60%) cases in Group 1 (continuous). Against-the-rule (ATR) astigmatism was seen in 6 (20%) patients in Group 2 and 10 (33.3%) patients in Group1. Four (13.3%) patients were astigmatically neutral in the interrupted group and 2 (6.7%) in the continuous group [Figure - 3].

The uncorrected visual acuity (UCVA) at the end of 6 weeks was 6/6 in 6 (20%) patients in Group 1 and 8 (26.6%) in Group 2. Nineteen (63.3%) patients had a UCVA of 6/9 in the first group and 21 (70%) in the second group. No patient in Group 2 had UCVA <6/12 whereas two patients in Group 1 had a UCVA of 6/18 [Table - 2].

One patient in Group 1 had a BCVA of 6/18 and one patient in Group 2 had a BCVA of 6/12 due to age-related macular degeneration. Two patients in Group 1 had BCVA of 6/12 due to posterior capsular opacification. Two other patients in Group 1 with BCVA of 6/12 had macular hole and age-related macular degeneration respectively [Table - 2].


  Discussion Top


The incidence of cataract blindness in Nepal is 66.8%; 5.3% is due to sequelae of cataract.[2] An estimated 78,605 individuals are bilaterally blind from cataract and one- fourth of these people live in the eastern region.[2] As estimated in 1997, the backlog of unoperated cataract in the world is 20 million, and a majority of these patients live in the developing countries.[3] In a recent survey[4] in 1998, 5.3% of the examined individuals were blind, and cataract was the principal cause in 78% of the cases. Considering both cataract operated and unoperated cataract-blind cases, the surgical coverage was approximately only 42%.

In spite of the recent trend towards manual small incision cataract surgery and phacoemulsification, conventional cataract surgery continues to be seen as a satisfactory and comfortable technique by the majority of surgeons. Therefore this method is routinely used here, in hospital-based camps. Despite intraocular implants, a majority of patients require spectacles after surgery. This is due to a large amount of astigmatism secondary to corneal distortion, which is distressing to the patient as well as to the surgeon.[5] Disappointing visual results ensue even in a well-performed surgery. Major determinants of postoperative astigmatism are the size and site of incision, type of suture and suturing technique. In the present study, the last variable was used for comparison. The first three factors were constant in both study groups. Only corneal (keratometric) astigmatism was computed in our study, as induced astigmatism is most frequently due to corneal scleral suturing and not tilting of the pseudophakos.[6]

Our study showed that continuous sutures induced astigmatism of 3.53 2.19 D, is comparable with the previous two studies.[7],[8] A few earlier studies reported marginally less astigmatism in continuous sutures as compared to our study, i.e., 0.68 D and 1.00 D.[9],[10] Interrupted sutures induced astigmatism of 1.7 1.35 D in our study. Astigmatism ranging from 0.78 D to 1.44 D has been shown in past studies.[11],[12],[13],[14] Very few studies have compared the astigmatism induced by interrupted and continuous sutures [Table - 3]. All these studies used 10-0 monofilament nylon for suturing and keratometry for measuring astigmatism. Our comparative study emphasised that interrupted sutures induced significantly less astigmatism than continuous sutures. Some studies showed no significant difference between both types of suturing.[15],[16],[17] It was further suggested that the type of suture was a more important factor determining astigmatism than the type of suturing.[16]

The type of astigmatism at the end of 6 weeks was with-the-rule (WTR) in a majority of patients in both groups [Table - 4]. An initial WTR followed by ATR astigmatism finally, has been reported by some authors. [18],[19],[20] It has also been reported that continuous suturing commonly induces WTR while interrupted suturing commonly induces ATR.[21] A high incidence of WTR has been reported in all cases using 10-0 continuous monofilament and 8-0 silk interrupted sutures in the first two postoperative weeks. An early and pronounced shift to ATR astigmatism was seen in the interrupted group after two weeks, whereas in the 10-0 monofilament group there was no further change unless the suture was removed.[17]

We conclude that interrupted suturing induced significantly less astigmatism as compared to continuous sutures in our set up. Thus the reduction of astigmatism with the use of interrupted sutures ensures improved vision.

There is a need for further studies to analyse factors responsible for high astigmatism in continuous sutures.

 
  References Top

1.
Gelender H. Management of corneal astigmatism after cataract surgery. Refract Corneal Surg 1991;7:99-102.  Back to cited text no. 1
    
2.
Brilliant GE. The Epidemiology of Blindness in Nepal. Report of the 1981 Nepal Blindness Survey. Chelsea: The Seva Foundation, 1980. pp 156-205.  Back to cited text no. 2
    
3.
Thylefors B. A global initiative for elimination of avoidable blindness. Community Eye Health 1998;11:1-2.  Back to cited text no. 3
    
4.
Pokharel GP, Regmi G, Shreshtha SK, Negrel AD, Ellwein LB. Prevalence of blindness and cataract surgery in Nepal. Br J Ophthalmol 1998;82:593-94.  Back to cited text no. 4
    
5.
Moore JG. Incidence of astigmatism after cataract surgery. Comparison of continuous and interrupted sutures. Trans Ophthalmol Soc UK 1977;97:104.  Back to cited text no. 5
    
6.
Barron GJ, Villasenor RA, Weber M. Correction of induced astigmatism after cataract surgery with introduction of intraocular lens. Ophthalmic Surg 1977;8:110-12.  Back to cited text no. 6
    
7.
Luntz MH, Livingstone DG. Astigmatism in cataract surgery. Br J Ophthalmol 1977;61:360-65.  Back to cited text no. 7
    
8.
Thygesen J, Reersted P, Fledelius H, Corydon L. Corneal astigmatism after cataract extraction. A comparison of corneal and corneoscleral incisions. Acta ophthalmol (Copenh) 1979;57:243-51.  Back to cited text no. 8
    
9.
Skubiszewska T, Mrzyglod S, Warczynski A, Krzysztofik R. Corneal astigmatism after tunnel incision for cataract extraction. Klin Oczna 1996;98:429-32.  Back to cited text no. 9
    
10.
Bellucci R, Morselli S, Pucci V, Palamara A. Corneal topography and astigmatism after superior sutured 8 mm scleral tunnel incisions. J Cataract Refract Surg 1996;22:690-95.  Back to cited text no. 10
    
11.
Rowan PJ. Corneal astigmatism following cataract surgery. Ann Ophthalmol 1978;10:231-34.  Back to cited text no. 11
    
12.
Brown NA. Control of astigmatism in Cataract surgery. Br J Ophthalmol 1988;72:487-93.  Back to cited text no. 12
    
13.
Talamo JH, Stark WJ, Gottsch JD, Goodman DF, Pratzer K, Cravy TV, et al. Natural history of corneal astigmatism after cataract surgery. J Cataract Refract Surg 1991;17:313-18.  Back to cited text no. 13
    
14.
Bansal AK, Gutpa A, Grewal SP. Selective suture cutting for control of astigmatism following cataract surgery. Indian J Ophthalmol 1992;40:71-73.  Back to cited text no. 14
    
15.
Stainer GA, Binder PS, Parker WT, Perl T. The natural and modified course of post cataract astigmatism. Ophthalmic Surg 1982;13:822-27.  Back to cited text no. 15
    
16.
Dekkers NW, Buijs J. Corneal astigmatism after cataract surgery. Doc Ophthalmol 1989;72:323-27.  Back to cited text no. 16
    
17.
Wishart MS, Wishart PK, Gregor ZJ. Corneal astigmatism following cataract extraction. Br J Ophthalmol 1986;70:825-30.  Back to cited text no. 17
    
18.
Axt JC. Longitudinal study of post-operative astigmatism. J Cataract Refract Surgery 1987;13:381-88.  Back to cited text no. 18
    
19.
Masket S. Keratorefractive aspects of scleral pocket incision and closure method for cataract surgery. J Cataract Refract Surgery 1989;15:70-77.  Back to cited text no. 19
    
20.
Catalin C, Kreolla A, Carmen R. The evolution of corneal astigmatism after cataract surgery. Oftalmologia 1998;45:57-62.  Back to cited text no. 20
    
21.
Meredith TA, Maumenee AE. A review of one thousand cases of intracapsular cataract extraction. ii. Visual results and astigmatic analysis. Ophthalmic Surg 1979;10:42-45.  Back to cited text no. 21
    


    Figures

  [Figure - 1], [Figure - 2], [Figure - 3]
 
 
    Tables

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


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