Untitled Document

ORIGINAL ARTICLE

Year : 2021 |  Volume : 3 |  Issue : 2|  Page : 6-11

1
 Comparitive study of astigmatic changes following pterygium excision with conjunctivallimbalautograft with sutures versus sutureless
P Rachana1, Jayashree S Shah2*
1* Postgraduate Student, 2 Professor and  Head, Department of Ophthalmology. Sri Siddhartha Medical College, SSAHE, Tumkur Karnataka India
* Address for Correspondence:
Jayashree S Shah, Professor and HOD, Department of Ophthalmology, SSMC, SSAHE, Tumkur
E-mail;drjss33@gmail.com
Abstract
Background: A comparative study to assesss the amount of changes in corneal astigmatism after pterygium excision by using two surgical techniques.  Materials and methods: Total of 60 cases diagnosed with primary pterygiumwere included in the present study and the patients are randomly allotted into two groups which has 30 in each group. Surgical technique include one group with ConjunctivalLimbalautograft with suture and the other group with ConjunctivalLimbalAutograftsutureless. All selected patients pre operatively  underwent detailed ocular examination which include visual acuity using Snellen's chart, anterior and posterior segment examination, grading of pterygium. Refraction recorded using auto refractometer .post operatively patients are assessed for visual acuity, refractometry on 1st week, 1month, 3month respectively and  results were analysed. Results: In the study 34 patients (56.6%) were male, 26 patients (43.3%) are female and age ranging from 15-55 years. The preoperative mean refractive astigmatism in suture group 2.55±1.23 and statistically decreased to 0.80±0.89D which was statistically significant (p<0.001), the preoperative mean refractive astigmatism in sutureless 2.03±1.17D decreased to 0.68±0.82D which was statistically significant (p<0.001). pre operatively mean visual acuity in suture group 0.59± 0.25 which improved to 0.87 ±0.17 which was stastistically significant(p=0.002). The preoperative mean visual acuity in sutureless group 0.63±0.24 which improved to 0.96±0.12 which was statistically significant (p=0.002). Conclusion:cpterygium excision results in significant reduction in astigmatism and improvement in visual acuity. Both surgical techniques are equally effective in reducing astigmatism and improvement of visual acuity.
Key words:  pterygium,conjunctivallimbalautograft, astigmatism,visual acuity

Introduction
Pterygium is a wing shaped fibrovascular growth of the conjunctival connective tissue which grows over the cornea which results in cosmetic problem,reduced vision due to astigmatism and optical axis blockage.[1]Pterygium is derived from Greek word “pteryx” meaning wing.[2]
Risk factors include immune mechanism, genetic predisposition, and chronic environmental irritation, like UV (ultraviolet) rays, hot and dry weather, wind, dusty atmosphere, and exposure period to such conditions. The prevalence rates are highest in “pterygium belt”as  described by Cameron, which lies between 37° north and south of the equator.
The prevalence rate varies widely from 0.3 to 29 percent in the world. In India, it ranges from 9.5 to 13%.[3]
Most common seen in elderly, new cases per annum seen higher in the younger age group. Males are more common , in Aruba it is equally in both sexes.[4] Induced astigmatism occurs due to the tractional force of contractile elements which  leads mechanical distortion which results in  flattening  the cornea on  horizontal meridian which results in  hypermetropic with the rule  astigmatism.[1]
Tear film pooling and Pterygium size also results in astigmatism [6]
Grading of pterygium Grade I - crossing limbus, Grade II - midway between limbus and pupil, Grade III - reaching up to pupillary margin, Grade IV - crossing pupillary margin.[7] Several surgical techniques have been  proposed for the management of pterygium. Commonly used surgical procedure is conjunctivallimbalautograft. Limbalautograft is usually fixed by using sutures, suturelessconjunctivalautograft a newer technique.[8]
In our study our aim was to study the amount of astigmatic changes after pterygiumexcision surgery and to investigate effect of surgery type on pterygium induced astigmatism.
Methods and materials
This was a prospective study and includes 60 patients and the sample for the present study were taken from those attending ophthalmology OPD with primary pterygium  at Sri Siddhartha Medical College. Inclusion criteria-the study population includes primary pterygium cases. Exclusion criteria – cases of reccurentpterygium, occular surface disease, Sjogren syndrome, dry eye disease, Pseudopterygium are excluded from the study.

After obtaining the informed consent from the patient, the detailed history of the patient was taken and detailed ocular examination was done which include visual acuity examination using snellen chart, slit

lamp examination was done for anterior segment evaluation to look for tear film abnormality, to look for extent and nature of pterygium and corneal scaring. Pre and post refraction was recorded using auto refractometer which is Unique – RK (URK800). Posterior segment evaluation was done to look for posterior segment pathology. The patients will be then  divided into two groups, patients are randomly allotted into the groups, which contains 15 in one group.Intraoperative time was noted into each group, single surgeon conducted the surgeries.
Sutureless Group –Operated with conjunctivallimbalautograftwith out suture.
Wire speculum is inserted, sub pterygium injection given with 2% lignocaine. Head of the pterygium is cut, rest of the pterygium is separated from subtenon's  leaving bare sclera. Size of the bare sclera is measured with capillers, the superior temporal quadrant of the bulbar conjunctiva is injected with 1cc of local anaesthesia to separate conjunctiva from tenon's capsule. Careful blunt dissection with wetcott scissors is performed until the graft is free from tenon's reaching the limbus. Forceps is used to slide the graft on to the bare sclera keeping the limbal edge towards the limbus. The graft is position in place. Stability of graft was tested using bud. Pad and bandage is applied.
Operated with conjunctivallimbalautograft with suture wire speculum is inserted, sub pterygium injection given with 2% lignocaine. Head of the pterygium is cut, rest of the pterygium is separated from subtenon's  leaving bare sclera . Size of the bare sclera is measured with capillers, the superior temporal quadrant of the bulbar conjunctiva is injected with 1cc of local anaesthesia to separate conjunctiva from tenon's capsule. careful blunt dissection with wet cott scissors is performed until the graft is free from tenon's reaching the limbus. Forceps is used to slide the graft on to the bare sclera keeping the limbal edge towards the limbus. The graft is position in place and sutured with 10-0 vicryl. Pad and bandage applied.
Patients were followed at POD-1,one week, one month, 3 months and 6 months. All cases were given steroids postoperatively 6 times a day for 1 week which is tapered and stopped in the sixth week of follow up.
Statistical analysis
Quantitative variables were expressed as mean and standard deviation and qualitative variables were expressed as frequencies and percentages. Association between categorical variable were tested using Chi-square test. Continuous variables were tested for normality. Non-parametric test like Mann-Whitney U test was applied to compare between two groups. Pre and post comparison was done using Wilcoxon Signed Rank test. P-values less than 0.05 was considered statistically significant. All the statistical analysis was carried out using SPSS software (Version-20).
Results
The study contains total of 60 cases of which includes  34 male patients of 56.6% and 26 female patients of 43.3% which is shown in the Table 1, Figure 1 shows more of male patients in the study. This study includes 28  patients with grade 1 pterygium, 20 patients with grade II and 12  patients with gradeIII which is shown in Table 2 and Figure 2.

Table 1: Age and sex distribution of patients


Sex

N

%

Age

Mean

Median

Std. Deviation

Minimum

Maximum

Male

34

56.6%

34.41

32.00

10.00

19

54

Female

26

43.3%

28.85

28.00

10.38

15

50

Total

60

100%

32.00

30.50

10.38

15

54

Figure 1
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Table 2: Distribution by grade and type of procedure


Grade

Suture

Sutureless

Total

Chi-Square, P-value*

Grade 1

12 (40.0%)

16 (53.3%)

28 (46.7%)

0.952,
0.621

Grade 2

10(33.3%)

10(33.3%)

20 (33.3%)

Grade 3

8(26.7%)

4(13.3%)

12 (20.0%)

Total

30 (100.0%)

30 (100.0%)

60 (100.0%)

*Chi-Square test


Figure 2
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Table 3: Comparison of Astigmatism between surgery types


Astigmatism

Surgery type

N

Mean

Std. Deviation

Median

Z

P-value*

Pre-Operative

Suture

30

2.55

1.23

3.25

-1.715

0.087

Sutureless

30

2.03

1.17

1.50

Post-Operative

Suture

30

0.80

0.89

0.50

-0.38

0.704

Sutureless

30

0.68

0.82

0.50

* Mann-Whitney U test
Table 4: Pre and post-operative comparison with and without suture


Type

Surgery type

N

Mean

Std. Deviation

Median

Z-value

P-value*

Suture

Astigmatism Pre

30

2.55

1.23

3.25

-3.306

<0.001

Astigmatism Post

30

0.80

0.89

0.50

Sutureless

Astigmatism Pre

30

2.03

1.17

1.50

-3.312

<0.001

Astigmatism Post

30

0.68

0.82

0.50

*Wilcoxon Signed Rank test

30 patients were incuded in the suture group which shows mean pre operative astigmatism of 2.55 ± 1.23 before the surgery and there are 30 patients included in the sutureless group which has mean pre operative astigmatism showing 2.03 ± 1.17 showed before the surgery. The mean post  astigmatism in suture group is 0.80 ± 0.89 and the mean astigmatism in sutureless group is 0.82 ± 0.50 which is shown in Table 3. Table 4 shows the amount of astigmatism changes in suture group before and after pterygium excision

surgery in suture group 2.55 ± 1.23 which decreased to 0.80 ± 0.89 and the mean astigmatic changes in the sutureless group before and after surgery shows from 2.03 ± 1.17 reduced to 0.82 ± 0.50 with p < 0.001 in both the groups which is statistically significant.
The mean UCVA in suture group is 0.59 ± 0.25 and the mean UCVA in sutureless group is 0.63 ± 0.24 , there is an increase in the visual acuity after the surgery the BCVA after the surgery in suture group is 0.87 ±0.17 and the mean BCVA in sutureless group is 0.96 ± 0.12 and both the group shows pvalue 0.002 which is statistically significant and is shown in Table 5.Table 6 shows BCVA according to pterygium  grade.
Table 7 & 8 shows astigmatic changes according to pterygium grade which shows mean preoperative  astigmatism in grade I was 1.18 ± 0.27, in grade II was 2.85 ± 0.69 , in grade III was 3.96 ± 0.25 and the mean post operative astigmatism showed in grade I 0.34 ± 0.25 ,grade II showed 1.13 ± 0.88 and in grade III was 1.04 ± 0.63 which shows grade III showed more reduction of astigmatism.
Table 5: Comparison of Uncorrected and corrected Visual Acuty with and without suture


Type

Visual Acuty

N

Mean

Std. Deviation

Median

Z

P-value

Suture

UCVA Pre

30

0.59

0.25

0.67

-3.108

0.002

BCVA Post

30

0.87

0.17

1.00

Sutureless

UCVA Pre

30

0.63

0.24

0.67

-3.106

0.002

BCVA Post

30

0.96

0.12

1.00

*Wilcoxon Signed Rank test
Table 6: Comparison of UCVA and BCVA between grades


Visual Acuty

Grade

N

Mean

Std. Deviation

Median

Chi-Square

P-value

UCVA

Grade 1

28

0.75

0.67

0.17

15.978

<0.001

Grade 2

20

0.60

0.59

0.18

Grade 3

12

0.29

0.21

0.16

BCVA

Grade 1

28

1.00

1.00

0.00

10.545

0.005

Grade 2

20

0.87

1.00

0.17

Grade 3

12

0.78

0.67

0.17

*Kruskal-Wallis test
Discussion
Most of the cases pterygium is symptomless, vision is decreased only once it encroaches the pupillary region of cornea[9]. Pterygium induced refraction cause decrease in the vision because of increase in astigmatism or because of visual axis covered due to pterygium.[10] In FarhadRezvan et al study showed men having the prevalence rate of 13% when compared to females.[11] In Fotouhi et al study found that the prevalence rate in male was 1.4% where in females was 1.1% which showed high prevalence in men[12] In our study  majority of the cases are male 34 (56.6%) where females are 26 (43.3%) which shows pterygium is most commonly seen in males when compared to females. In the study conducted by Altan et al showed  the mean preoperative  astigmatism was 3.47 ± 2.50 D. The mean astigmatism decreased to 1.29 ± 1.07 D after surgery.[1] In Faisal et al study include thirty patients who underwent pterygium excision surgery in which the median preoperative astigmatism was 2.25D and the median  post astigmatism reduced to 1.30D after the surgery and  concluded that there is significant decrease in corneal astigmatism after pterygium excision which showed and the post operative astigmatism was statistically significant(pvalue<0.001)[13] in our study the median preoperative astigmatism in suture group is 3.25D and reduced to 0.50D and in sutureless group the median preoperative astigmatism is 1.50D to 0.50D. Our study showed reduction in astigmatism after the surgery in both groups which shows that pterygium causes astigmatism by flattening the cornea and can be decreased after the excision of the pterygium. In suture group mean preoperative astigmatism was 2.55 ± 1.23D and reduced to post operative astigmatism 080 ± 0.89, and sutreless group with mean preoperative astigmatism of 2.03 ± 1.17 and decrease in post operative astigmatism to 0.68 ± 0.82 and both the groups are statistically  significant in reducing the stigmatism  (p <0.001) In our study astigmatism in grade 1 was 1.18 ± 0.27 which reduced to 0.34± 0.25, in grade II 2.85±0.69 reduced to 1.13± 0.88, in grade III it was 3.96 ± 0.19 which decreased to 1.04 ±0.63 reduction of astigmatism  is more in grade III and we also found decrease in astigmatism was also related to the size of the pterygium. Our study showed  increase in the visual acuity in both the groups  afterpterygium excision (p = 0.002)  in both the groups,in suture group UCVA was 0.59 ± 0.25 which increased to 0.87 ± 0.17, in sutureless group UCVA was 0.63 ± 0.24 and increased to BCVA 0.96 ± 0.12. In the  study conducted by Heena et al showed there is improvement in BCVA with reduction in cylindricals after the surgery which was 1 ± 0.75D to 0.75 ± 0.50D after the surgery.[10] In the study conducted by maheshwari et al showed increased in the vision after pterygium excision which showed the BCVA pre operative was 0.53 ± 0.35D and postoperative BCVA increased to 0.68 ± 0.34D.[14]
Conclusion
Pterygium causes corneal astigmatism by flattening the cornea, the present study found that surgical excision of pterygium leads to reduction in astigmatism and improvement in the visual acuity. According to our study CLAG with sutures showed decrease in astigmatism and improvement in the vision  and CLAG  with sutureless also showed reduction in corneal astigmatism and also improvement in the vision, so both the techniques are effective in reducing astigmatism and improving the vision.
Acknowledgement: Nil
Financial support and sponsorship: Nil
Conflict of interest: Nil
References
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2.   Chaudhurizia, M Vanathi. pterygium. In: post graduate  ophthalmology. 2nd ed. Jaypeebrothers diseases of concunctiva. 2020 ; 2(1): 584–88.
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