a comparative study of surgically induced astigmatism in superior, supero-temporal and temporal...

A COMPARATIVE STUDY OF SURGICALLY INDUCED ASTIGMATISM IN SUPERIOR, SUPERO-TEMPORAL AND TEMPORAL INCISION IN SMALL INCISION CATARACT SURGERY IN A RURAL HOSPITAL

Presented by: Co-author:Dr Madhumita Prasad Dr Sachin Daigavane

INTRODUCTION• Cataract is the main and biggest cause of curable blindness in

India and worldwide. The annual incidence of cataract in India has been estimated to be 3.8 million[1] and 1.8 million sight-restoring operations are performed every year.[2]

• Cataract surgery has become one of the most common and successful procedures in ophthalmology.

• Small incision manual extracapsular techniques (SICS) - the first choice alternative to phacoemulsification as it retains most of the advantages of "phaco" giving visual results equivalent to phacoemulsification at lower cost.

• Minimal postoperative astigmatism, rapid visual rehabilitation and the best corrected visual acuity possible are the aims of modern cataract surgery. The axiom today in rehabilitation of a patient of cataract is “Small is beautiful”[3].

AIMS AND OBJECTIVES:• To compare between the surgically induced astigmatism(SIA) in

small incision cataract surgery(SICS) by superior incision , temporal incision and supero-temporal incision.

• To evaluate change in preoperative and postoperative astigmatism.• To study the effect of three different incision sites on post-

operative best corrected visual acquity.

MATERIAL AND METHODS• This was a randomized prospective comparative study. • A total of 150 eyes of patients attending the Ophthalmology OPD were

studied. • The patients were randomly assigned to any of three groups. Each group

had 50 patients. The patient in group A underwent SICS with superior tunnel incisions. Patients in group B underwent SICS with supero-temporal tunnel incisions and patients in group C underwent SICS with temporal tunnel incisions.

• INCLUSION CRITERIA: The patients with nuclear and cortical cataracts ranging from grade 1 to hypermature cataracts and posterior Sub-capsular cataracts and giving consent.

• EXCLUSION CRITERIA:The patients with any intraocular pathologies of anterior segment and posterior segment and not giving consent.

• The patients were examined on the 1st , 7th and 45th post-operative days for best corrected visual acuity, under slit lamp and also auto-refractometer and keratometry were done.

• The mean SIA were calculated at the 45th post-operative day. All the surgically induced astigmatism (SIA) were calculated by Vector Analysis method.

OBSERVATIONS:TABLE 1: DISTRIBUTION OF PRE-OPERATIVE CORNEAL ASTIGMATISM IN 3 GROUPS

KERATOMETRIC ASTIGMATISM IN

DIOPTERS(D)

GROUP An(%)

SUPERIOR INCISION

GROUP Bn(%)

SUPERO-TEMPORALINCISION

GROUP Cn(%)

TEMPORAL INCISION

0-0.5D 22 20 26

0.75-1.00 D 13 17 15

>1.00 D 15 13 9

Total 50 50 50

In group A ,mean preoperative astigmatism was 1.52±1.02. In group B, mean preoperative astigmatism was 1.38±1.03. In group C, mean preoperative astigmatism was 1.26±1.01. 2א -value – 2.87, P value- 0.57,

non-significant.

TABLE 2: DISTRIBUTION OF POST-OPERATIVE CORNEAL ASTIGMATISM IN 3 GROUPS AT DAY 1


DIOPTERS(D)

GROUP An(%)

SUPERIOR INCISION

GROUP Bn(%)


GROUP Cn(%)

TEMPORAL INCISION

0-0.5D 10(20) 23(46) 15(30)

0.75-1.00 D 19(38) 18(36) 24(48)

>1.00 D 21(42) 9(18) 11(22)

Total 50 50 50

2א -value – 12.44, p value- 0.014, significant.

TABLE 3: DISTRIBUTION OF POST-OPERATIVE CORNEAL ASTIGMATISM IN 3 GROUPS AT 7TH DAY


DIOPTERS(D)

GROUP An(%)

SUPERIOR INCISION

GROUP Bn(%)


GROUP Cn(%)

TEMPORAL INCISION

0-0.5D 9(18) 24(48) 14(28)

0.75-1.00 D 17(34) 19(38) 24(48)

>1.00 D 24(48) 7(14) 12(24)

Total 50 50 50


TABLE 4: DISTRIBUTION OF POST-OPERATIVE CORNEAL ASTIGMATISM IN 3 GROUPS AT 45TH DAY


DIOPTERS(D)

GROUP An(%)

SUPERIOR INCISION

GROUP Bn(%)


GROUP Cn(%)

TEMPORAL INCISION

0-0.5D 8(16) 25(50) 16(32)

0.75-1.00 D 18(36) 17(34) 23(46)

>1.00 D 24(48) 8(16) 11(22)

Total 50 50 50

The mean post operative astigmatism was – 0.41±1.15 in group A.In group B, the mean post operative astigmatism was 1.56±1.23.In group C, the mean post operative astigmatism was 1.64±1.30.


TABLE 5: DISTRIBUTION OF POST-OPERATIVE SURGICALLY INDUCED ASTIGMATISM IN 3 GROUPS AT 45TH DAY(VECTOR ANALYSIS METHOD)

SURGICALLY INDUCED ASTIGMATISM IN

DIOPTERS(D)

GROUP An(%)

SUPERIOR INCISION

GROUP Bn(%)


GROUP Cn(%)

TEMPORAL INCISION

-1-0 D 10 27 23

1.00-2.00 D 15 14 15

>2.00 D 25 9 12

Total 50 50 50

2א -value – 17.38, p value- 0.0016 , significant.The mean SIA in group A was, -2.05±1.19.The mean SIA in group Bwas, 0.53±0.51.The mean SIA in group C was, 0.46±0.43.

TABLE 6: POST OPERATIVE BEST CORRECTED VISUAL ACQUITY IN 3 GROUPS AT 45TH DAY

POST-OPERATIVE BCVA AT 45TH DAY

GROUP An(%)

SUPERIOR INCISION

GROUP Bn(%)


GROUP Cn(%)

TEMPORAL INCISION

6/6-6/9 19 20 22

6/12-6/18 17 30 18

6/24-6/60 13 0 9

<6/60 1 0 1

TOTAL 50 50 50

2א -value – 18.15, p value- 0.005 , significant.

TABLE 7: PRE, POST AND SURGICALLY INDUCED ASTIGMATISM IN 3 GROUPS

GROUP An(%)

SUPERIOR INCISION

GROUP Bn(%)


GROUP Cn(%)

TEMPORALINCISION

P VALUE

Mean preoperative

astigmatism(D)

1.52±1.02 1.38±1.03 1.26±1.01 P>0.57

Mean postoperative

astigmatism(D)

– 0.41±1.15 1.56±1.23 1.64±1.30 P<0.0005

Mean SIA astigmatism(D)

-2.05±1.19 0.53±0.51

0.46±0.43 P<0.0016

SICS which is done with a temporal and a supero-temporal approach provides a better quality of vision due to a significantly less SIA than the superior approach.

REFERENCES

1. Minassian DC, Mehra V. 3.8 million blinded by cataract each year: Projections from the first epidemiological study of incidence of cataract blindness in India. Br J OphthalmoI1990;74:341-3.

2. Jose R, Bachani D. World Bank-assisted Cataract Blindness Control Project. IndianJ Ophthalmoll995 ;43:35-43.

3. Naeser K. Assessment of surgically induced astigmatism; call for an international standard [letter] J Cataract Refract Surg. 1997; 23:1278–1280 8. Naeser K. Assessment of surgically induced astigmatism; call for an international standard [letter] J Cataract Refract Surg. 1997; 23:1278–1280

a comparative study of surgically induced astigmatism in superior, supero-temporal and temporal...

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