Young patient's age determines pterygium recurrence after surgery.

BACKGROUND
It is not clear whether demographic or pterygium characteristics or limbal stem cell deficiency determine pterygium recurrence after surgery.


PURPOSE
To determine whether the demographic, pterygium characteristics, or limbal stem cell deficiency determine pterygium recurrence after excision.


METHODS
Of 190 patients operated and followed-up for 6 months, 101 and 89 underwent free conjunctival autotransplant (CAT) or limbal conjunctival autotransplant (LCAT) respectively. The age, gender, occupation, grade of pterygium extent and degree of fleshiness, and laterality were compared between recurrent and no recurrent pterygia. Multivariate analysis was performed to determine the predictors of pterygium recurrence. Recurrence rates after surgery were compared between CAT and LCAT.


RESULTS
The age range of the 190 patients was 22-65 years, mean ±SD 46.4 ±10.8 years. Pterygium recurred in 52 (27.4%). Thirty-nine (75%) of 52 patients with pterygia that recurred were aged <50 years (young) vs. 72 (52%) of 138 young patients with no recurrence; odds ratio (OR) = 1.54; 95% confidence interval (95% CI) = 0.70-3.36; p = 0.28. Thirty-one (60%) of 52 participants with post-surgical recurrent pterygia had large pre-operative pterygium (grade ≥3) vs. 130 (94%) of 138 patients with large pterygia that did not recur; OR = 0.11; 95% CI = 0.04-0.28; p <0.001. Of 101 patients undergoing CAT, 29 (28.7%) experienced recurrence vs. 23 (25.8%) of 89 undergoing LCAT; p = 0.66.


CONCLUSIONS
Young age seems to be associated with pterygium recurrence after excision followed by conjunctival graft. Large pterygia were protective.


Methods
A prospective randomised study was designed.Clearance was obtained from the 2 institutional research ethics committees and the clinical trials register number NCT 00713180 at nih.gov was obtained before starting the study.The tenets of the Declaration of Helsinki (2000)  were followed in obtaining consent.One hundred seventy six patients (88 per group) were needed to detect a 15% difference in recurrence rates between CAT and LCAT at an alpha value of 5% and a power of 80%, assuming a base recurrence rate of 20% in CAT.This assumption was based on a reported recurrence rate of 21% following CAT in a similar population. 6Because the present study factored a default rate of 12%, 200 patients were operated-on.The 200 patients comprised 120 who had participated in an earlier epidemiological study and 80 others who were interviewed and examined in the same way those in the epidemiological study. 12The indications for surgery were corneal astigmatism, obstruction or threatened obstruction of vision, disfigurement, or frequent inflammation. 13No patient had received topical antiinflammatory treatment before surgery.Participants were recruited and randomised to CAT or LCAT as adjunctive treatment to pterygium excision.Age, sex, occupation, pterygium extent and degree of fleshiness, 5 and laterality were recorded.Pterygium extent was assessed as previously described by Youngson. 14Grade 1 was a growth that had just crossed the limbus; grade 2 was approaching half of the corneal radius; grade 3 crossed half of the radius; grade 4 extended up to the corneal centre; and according to Carmichael (personal communication August 2007), grade 5 crossed the corneal centre.Between 2008 September and 2011 July, the patients underwent pterygium excision and treated as reported earlier. 11Only one eye per patient was enrolled in the study.The pterygia were excised at 4mm from the limbus and at the superior and inferior borders of the growth.The head was dissected off using a crescent knife.The grafts, which were harvested 1mm larger than the host pterygium were sutured-in using 10/0 nylon.Postoperative treatment consisted of topical ciprofloxacin 3mg/ml four times daily for one week, and prednisolone acetate 10mg/ml four times daily for 4 weeks.Sutures were removed at 1 month following surgery. 8The patients were followed-up for possible recurrence for a minimum duration of 6 months because a prospective study has reported that 94% of recurrences occurred within 6 months. 1 Recurrence was defined as a wing-shaped re-growth of fibrovascular tissue at the site of previous pterygium, 5 which was confirmed by a masked ophthalmologist.

Data analysis
Demographic and pterygium factors were compared in the patients whose pterygia recurred and those in whom pterygia did not recur after excision.The odds ratios (ORs) for recurrence and their 95% confidence intervals (CI) and significances were calculated using Chi-square test.Multivariate analysis was performed that only included factors that significantly determined pterygium recurrence in univariate analyses.Recurrence rates were compared between CAT and LCAT using Chi-square test.Statistical significance was tested by Student t test in continuous variables and Chi-square test in categorical variables.P ≤0.05 was considered to be significant.STATA 9 for widows software (STATA Corporation, College Station, USA) was used for statistical calculations.

Results
All 200 patients had pterygia of fleshiness degree 3 (thick pterygia).After 10 patients were lost to follow-up, data were available for 190 patients who were followed-up for a minimum duration of 6 months.Their age range was 22-65 years with a mean ±SD of 46.4±10.8years.Pterygium recurred after excision in 52 (27.4%) of the 190 participants.Seven pterygia (13.5%) of 52 recurred within 1 month, 31 (59.6%) between 1 and 3 months, and 14 (26.9%), between 3 and 6 months.Of 38 pterygia that recurred within 3 months, 29 (76.3%)occurred in young patients (<50yrs) Similarly, 10 (71.4%) patients who experienced pterygium recurrence more than 3 months after surgery were young individuals.Table 1 shows the results of univariate regression analysis of the demographic and pterygium characteristics in participants whose pterygia recurred and those in whom pterygia did not recur after surgery.Recurrence was more frequent than no recurrence in young participants.Recurrence was less frequent than no recurrence after excision of large pterygia.It also presents the results of multifactorial analysis of factors that were significant predictors of pterygium recurrence in univariate regression analysis.The OR for developing pterygium recurrence in young patients decreased and was no more significant compared to the OR in univariate regression.In contrast, the OR for grade 3 or larger pterygia recurrence increased and remained significant.
One hundred and one (53.2%) of 190 participants underwent CAT whereas 89 (46.8%) underwent LCAT.Each participant was operated in only one eye.Table 2 shows the results of univariate regression analysis

Discussion
Despite recurrence of some large pterygia, large pterygia were protective against recurrence independently of the patients' old ages, which has not been reported before.This result contradicts an earlier study that reported that recurrence after surgery was associated with large pterygium extent. 7The contradiction is most likely to be due to the application of adjunctive treatment in a proportion larger than the bare sclera after pterygium excision in the present study.
Young age was not confirmed to be associated with recurrence independently of pterygium extent, which is consistent with a previous study that failed to confirm an association between young age and recurrence independently of pterygium fleshiness. 5However, the present study failed to confirm that fleshiness was associated with recurrence 5 perhaps because all the pterygia in the present study were fleshy.It looks as if thick pterygia that qualified for surgery were common in this study population.And it seems that fleshiness protected old patients from pterygium recurrence after excision followed by conjunctival graft.Yet fleshiness seems to have failed to protect young individuals from pterygium recurrence.It is unlikely that pterygium fleshiness was important for the growth to recur or not to recur after surgery.The present study did not corroborate previous studies that showed that young age is associated with recurrence independently of other significant factors. 1,2his is probably because this study excluded most small pterygia in old individuals due to a lack of indication for surgery, hence, the study found that large pterygium size was protective.
Pterygium progression is the reason for recurrence after surgery. 13Young age implicates growing pterygium in this study.Pterygium progress may be intrinsically controlled because of two possible explanations in the present study thus.Most of the patients had participated in an earlier study that found heredity to be associated with pterygium occurrence. 12Most of the recurrences occurred within three months after surgery, the majority of which were in young individuals, which is consistent with a previous report that observed that aggressive pterygia recurred within a short period after excision in young members of one family. 4Pterygium progression may explain the varying recurrence times after surgery.It is possible that pterygia with shorter recurrence times grow faster than those with longer recurrence times, the discrepancy being dependent on the difference in concentration of growth factors. 15lthough young age may be implicated in pterygium growth pterygia in nearly 65% of young individuals did not recur.It is possible that those pterygia had stopped growing thus; young age is not tantamount to progress.Since MMPs are underexpressed in fibroblasts and stroma of individuals with chronic solar conjunctivitis, 16 suggesting presence of transforming growth factor-beta, 17 we imagine that a decrease in available growth factors to a level that is insufficient to promote fibrovascular proliferation that causes pterygium, yet enough to suppress MMPs may well explain lack of pterygium progress.Fibroblast mitotic rate has been shown to be proportional to the level of growth factors. 15t is maybe that pterygia that had stopped growing at a young age would be still small and thick later in life and would not recur after surgery. 1 However, it is clear that most pterygia in the present study had grown larger.Since some large pterygia recurred after excision irrespective of the patients' age, this suggests that growth continued in those large pterygia and that pterygium growth is independent of chronological age.Notwithstanding sunlight exposure in all patients whose pterygia recurred, sunlight is unlikely to determine recurrence.However, sunlight irrespective of its duration of exposure might be just a trigger for recurrence after surgery.
CAT and LCAT procedures appeared to have similar recurrence rates, which has been reported before. 2,11ecause the present study had a large sample, and it was prospective, the similar post-surgical outcome suggests that recurrence after excision of primary pterygium is unlikely to be due to limbal stem cell deficiency.This is consistent with our previous report on the follow-up investigation of pterygium samples from the present study's participants, which showed a lack of association between damaged limbal stem cells and pterygium. 18As we are finalizing this paper we are not aware of a study that has reported that LCAT was superior than CAT in the treatment of primary pterygia.

Conclusions
Young patient's age determines pterygium recurrence after surgery, and large pterygium extent appears to be protective.Recurrence after excision of primary pterygium seems unlikely to have a relationship with limbal stem cell deficiency.For the sake of simplicity and to avoid potential damage to normal limbal stem cells at the donor area, free conjunctival grafting is to be preferred over limbal conjunctival grafting for treatment of primary pterygium.

Table 1 :
Univariate and multivariate analysis of demographic and pterygium characteristics in patients with recurrence and those with no recurrence.Crude Adjusted

Table 2 :
Demographic and pterygium characteristics of patients operated, and surgical outcome +Student t-test; *Chi-square test of the demographic and pterygium characteristics, as well as surgical outcome in participants who underwent CAT or LCAT.The proportions of the patients were similar in the two groups with regard to demographic and pterygium characteristics.