Aditya S Parmar^1*, M B Dongre², E B Shelke³, H N Yerkade⁴

¹Junior Resident, ²Professor & HOD, ³Associate Professor, ⁴Assistant Professor, Department of Ophthalmology, S.R.T.R.G.M.C., Ambajogai, Beed, Maharashtra, INDIA.

Email: : adi8392@gmail.com , dr.mbd@rediffmail.com , ebshelke35@gmail.com, harshalyerkade@gmail.com

Out of the 100 patients that were operated, 8 patients (8%) had no change in manifest astigmatism, 2 (2%) patients had increase, and the remaining 90 patients (90%) had improvement in manifest astigmatism. 8 patients out of these 90 patients had been rendered free of spectacle/contact lens usage, i.e. their manifest refraction was nil. In our study, the pre-operative mean astigmatism by manifest refraction in Grade 1 pterygium was 0.66 D, which increased to 1.25 D in Grade 2 pterygium and further to 1.46 D in Grade 3 pterygium. The P value by ANOVA test was <0.008, which showed there was a highly significant increase in astigmatism with increasing grade/size of pterygium. The post-operative mean astigmatism by manifest refraction in Grade 1 pterygium was 0.31 D, 0.61 D in Grade 2 pterygium and 0.61 D in Grade 3 pterygium. The P value which was <0.001 proved there was a highly significant difference in residual astigmatism with increasing grade/size of pterygium. Comparing the pre and post-operative astigmatism according to manifest refraction, P values for Grade 1, Grade 2 and Grade 3 were 0.007, 0.001 and 0.001 respectively. Therefore, there was a highly significant difference between pre and post-operative astigmatism in pterygium patients.

Figure 3: Post-operative complications

In our study out of 100 patients, only 16 patients had complications over the 3 month follow up period. The most frequently observed complication was subconjunctival hemorrhage (6 patients), followed by graft displacement (3 patients). 2 patients had chemosis and 2 had lid edema on post-operative day 1. 1 patient developed sclera thinning which presented at 6 week follow-up. One patient developed conjunctival cyst at 3 months and one patient developed Dellen ulcer at 3 months. Subconjunctival hemorrhage was seen on post-operative day 1 and was managed by oral Vitamin C supplementation and it subsided in all patients by post-operative day 14. Chemosis and Lid edema seen in immediate post-operative period was treated with topical Flurbiprofen 0.003% eyedrops and increasing the dose frequency of topical steroid+antibiotic combination and was cured by post-operative day 3. Scleral thinning was seen in one patient which was probably due to use bipolar cautery and was managed by multi-layered amniotic membrane grafting and suturing with 10-0 Ethilon. Graft displacement was seen in 3 patients on post operative day 1 and the patients were subjected to graft re-suturing. 1 patient developed Dellen ulcer on post-operative day 7. 1 patient developed conjunctival cyst on post-operative 3 months which was treated with excision followed with the same topical treatment. Notably, none of the patients developed recurrence, proving that pterygium excision with amniotic membrane grafting reduces recurrence of pterygium. However, a longer follow-up is required for a better documentation of recurrence. Majority of the complications were seen in the patients with Grade 2 pterygium, followed by Grade 3 pterygium patients. No complications were seen in Grade 1 pterygium patients. By using Chi-square test, P value was <0.277 which suggests no significant difference in post-operative complications with increasing size of pterygium. Such a distribution might be because a large majority (78%) of the patients had Grade 2 pterygium. However, the more serious complications like sclera thinning and Dellen ulcer were seen in patients with Grade 3 pterygium.

DISCUSSION

In our study, majority of the patients; i.e. 78 patients (78%) presented with Grade 2 pterygium. 13 patients (13%) had grade 3 pterygium and 9 patients (9%) had grade 1 pterygium. All patients had primary nasal pterygium. A study by Maheshwari S on 36 eyes showed that 16 eyes (44.45%) had Grade 2 pterygium, 12 eyes (33.33%) had grade 3 pterygium, 7 eyes (19.45%) had grade 4 pterygium and 1 eye (2.77%) had a double headed pterygium. None of the patients had Grade 1 pterygium in that study.² Pterygia do not only lead to visual impairment by invading the visual axis or distorting the central topography, but they also induce a focal corneal flattening and severe astigmatism.⁴ In the present study, maximum patients had 6/18(31 patients, 31%) unaided pre-operative vision and maximum patients had 6/9(43 patients, 43%) unaided post-operative vision. Out of the 100 patients, 95 patients (95%) had improvement in unaided visual acuity of one line or more on Snellen’s chart and the remaining 5 patients (5%) had no improvement in unaided visual acuity and none of the patients had deterioration in vision after surgery. Gumus et al. in their study of 40 eyes in 34 patients observed statistically lower uncorrected visual acuity in patients with pterygium in comparison to their uncorrected visual acuity after surgery.⁴ Previous studies have shown pterygium induces with-the-rule astigmatism.^5-7 In our study, all patients had with the rule astigmatism. It was observed on the basis of automated keratometry values, that the pre-operative astigmatism in Grade 1 pterygium was 0.83±0.66D, whereas, it increased to 1.38±0.61D in Grade 2 pterygium and further to 1.50±0.49D in Grade 3 pterygium. The P value<0.02 showed there was a significant increase in astigmatism with increasing grade/size of pterygium.  Avisar et al. conducted a study on 94 eyes with primary pterygium with the help of computerized topography and concluded that significant astigmatism was induced by pterygium larger than 1mm from the limbus and it tends to increase with increasing size of the pterygium. The study also suggested an early surgical intervention when the pterygium size was more than 1mm from the limbus.⁶ The results of pre-operative astigmatism were confirmed by checking manifest refraction in the patients. The pre-operative astigmatism by manifest refraction in Grade 1 pterygium was 0.66±0.72 D, which increased to 1.25±0.61 D in Grade 2 pterygium and further to 1.46±0.57 D in Grade 3 pterygium. The P value by ANOVA test was <0.008, thus, providing more evidence that there was a highly significant increase in astigmatism with increasing grade/size of pterygium. On comparing the pre and post-operative astigmatism by keratometry, Grade 1 pterygium patients had 0.83±0.66D astigmatism which reduced to 0.44±0.62D postoperatively with a highly significant P<0.002 showing a highly significant reduction in astigmatism after surgery. Similarly, Grade 2 pterygium patients had preoperative astigmatism 1.38±0.61D which reduced to 0.66±0.30D with P value<0.001. Grade 3 pterygium patients had preoperative astigmatism 1.50±0.49D which reduced to 1.06±0.65D after surgery, with P value<0.005. Therefore, there was a highly significant decrease in astigmatism after pterygium excision surgery. These findings were similarly seen on manifest refraction wherein all 3 classes showed highly significant reduction in astigmatism post-operatively. Maheshwari S in her study on 140 eyes with pterygium, observed refractive cylinder reduction from 1.94–2.24D to 0.78–1.07D, which is similar to our study.²In another study by her, the preoperative refractive cylinder was 4.60±2D, which improved to 2.20±2.04D with surgery.²Popat etal in his study on 100 eyes with pterygium showed that amount of corneal astigmatism induced by pterygium increases in direct proportion with the size of pterygium. Also, the postoperative decrease in astigmatism is also more in those patients with a larger pterygium. Mean astigmatism on keratometry was found to be 6.20±3.58D preoperatively which subsequently decreased to 1.20±1.27D on post-operative day 45.⁸ Garg P et al. studied the changes in corneal astigmatism before and after pterygium excision as well as with differences between various surgical techniques like bare sclera, conjunctival autograft, amniotic membrane graft. Changes in astigmatism were significantly more with amniotic membrane graft and conjunctival autograft technique as compared to the bare sclera technique, mainly due to better healing and less granulation tissue formation.⁹ Complications are known to occur in every ophthalmic surgery. In our study, out of 100 patients, only 16 patients had complications over the 3 month follow up period. The most frequently observed complication was subconjunctival hemorrhage (6 patients) which was managed by oral Vitamin C supplementation and it subsided in all patients by post-operative day 14. This was followed by graft displacement (3 patients) on post-operative day 1 and the patients underwent graft re-suturing. 2 patients had chemosis and 2 had lid edema on post-operative day 1. These patients were treated with topical Flurbiprofen 0.003% eyedrops and increasing the dose frequency of topical steroid+antibiotic combination and was cured by post-operative day 3. One patient developed conjunctival cyst at 3 months who was subjected to cyst excision at 3 months and one patient developed Dellen ulcer at 3 months. 1 patient developed scleral thinning which presented at 6 weeks follow-up who was managed by multi-layered amniotic membrane grafting and suturing with 10-0 Ethilon. Recurrence after pterygium surgery is a quite common phenomenon. Okoye et al. in their study with 30 eyes pterygium treated with surgery and amniotic membrane grafting had a recurrence rate of 6%.¹⁰ In a study conducted by Katircioglu et al., percentages of recurrence seen in groups of conjunctival autograft, amniotic membrane grafting and conjunctival autograft with adjuvant mitomycin C were 16%, 25% and 0% respectively.¹¹ Luaratanakorn etal in his study observed that the recurrence rate was 12.3%, 21.4% and 13.1% for primary, recurrent and all pterygia, respectively in patients with conjunctival autograft. In the amniotic membrane group, the recurrence rate was 25.0%, 52.6% and 28.1% for primary, recurrent and all pterygia.¹² However in our study, a longer follow-up is required for better evaluation of long term complication and recurrence. Although the recurrence was lower in conjunctival autograft, amniotic membrane grafting serves to be good alternative to it especially in cases with large defects, double pterygium or in cases where bulbar conjunctiva is required for future glaucoma filtration surgery. However, the use of amniotic membrane is limited by its high cost. Moreover, recurrence can be reduced by adjuvants like Mitomycin C. Using amniotic membrane reduces surgical time of harvesting the conjunctival autograft and using fibrin glue along with it, decreases further.

CONCLUSION

Our study suggests that early excision of pterygium with amniotic membrane grafting should be employed in all cases of pterygium as early as possible as it is safe, highly effective modality in the management of primary pterygium as it also reduces recurrence. However, a longer follow up is required for documentation of recurrence.

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