|Year : 1998 | Volume
| Issue : 4 | Page : 203-209
Conjunctival-Limbal autografts for primary and recurrent Pterygia: Technique and results
Srinivas K Rao, T Lekha, Bickol N Mukesh, G Sitalakshmi, Prema Padmanabhan
Medical Research Foundation, Chennai, India
Srinivas K Rao
Medical Research Foundation, 18 College Road, Chennai - 600 006
Source of Support: None, Conflict of Interest: None
Our technique of pterygium excision with conjunctival-limbal autografting is described and the safety and efficacy of the procedure in India is analysed. Case records of 51 consecutive patients (53 eyes) who underwent surgery at our institute between November 1992 and September 1994 were retrospectively analysed. Recurrence was defined as fibrovascular tissue crossing the corneoscleral limbus onto clear cornea in the area of previous pterygium excision. 2 (3.8%) of the 53 pterygia (primary 36; recurrent 17) recurred, after a mean follow up of 18.9±12.1 months (range: 1.5-43 months). Both recurrences occurred within a year of follow up, in patients who were ≤40 years of age. No major operative or postoperative complications were encountered. The inclusion of limbal tissue in conjunctival autografts following pterygium excision appears to be essential to ensure low recurrence rates. The technique is safe, simple and inexpensive and is recommended for the management of both primary and recurrent pterygia in Indian eyes.
Keywords: Conjunctival autograft, limbal transplantation, pterygium recurrence
|How to cite this article:|
Rao SK, Lekha T, Mukesh BN, Sitalakshmi G, Padmanabhan P. Conjunctival-Limbal autografts for primary and recurrent Pterygia: Technique and results. Indian J Ophthalmol 1998;46:203-9
|How to cite this URL:|
Rao SK, Lekha T, Mukesh BN, Sitalakshmi G, Padmanabhan P. Conjunctival-Limbal autografts for primary and recurrent Pterygia: Technique and results. Indian J Ophthalmol [serial online] 1998 [cited 2019 Jun 20];46:203-9. Available from: http://www.ijo.in/text.asp?1998/46/4/203/24166
A pterygium is a fibrovascular, wing-shaped encroachment of the conjunctiva onto the cornea. Ultraviolet light-induced damage to the limbal stem cell barrier with subsequent conjunctivalisation of the cornea is the currently accepted etiology of this condition., Indications for surgery include visual impairment, cosmetic disfigurement, motility restriction, recurrent inflammation, interference with contact lens wear and rarely, changes suggestive of neoplasia. The main histopathologic change in primary pterygium is elastotic degeneration of the conjunctival collagen. Recommended surgical management includes simple excision, with or without adjunctive measures like postoperative beta-irradiation, thiotepa drops, intraoperative and postoperative mitomycin-C and various techniques of conjunctival grafting. The reported success rates of these techniques vary widely, from 5% for pterygium excision with conjunctival autografting to 89% for simple excision. Initial experience with postoperative use of topical mitomycin-C indicated possible severe, sight-threatening complications. Although more recent studies,  have reported encouraging results and fewer side effects using low-dose intraoperative application of mitomycin-C, the optimal concentration and duration of application are still being refined. We report our technique and results of pterygium excision with conjunctival-limbal autografting in the management of advanced primary and recurrent pterygia occurring in India-a part of the "pterygium belt" described by Cameron.
| Materials and Methods|| |
Case records of 54 consecutive patients who underwent pterygium excision with conjunctival-limbal autografting between November 1992 and September 1994 were analysed retrospectively. Surgeries were performed by 3 surgeons. 3 patients were lost to follow up after surgery and were excluded from further analysis.
Patient data collected included age at surgery, sex, domicile in India, past ocular, medical and surgical history, indication for surgery, visual acuity and refraction before and after surgery, surgical technique and complications, postoperative medications, postoperative complications, recurrence and final cosmesis. Characteristics of the pterygia including location, size and extent across the cornea, indicators of inflammation, documented growth, and previous treatments were recorded.
For cases with less than 6 months' follow up, repeated attempts were made to reach the patients by mail or telephone. 3 successive letters were sent to patients residing outside Chennai at 1-2 month intervals along with a questionnaire. The patient was requested to have the questionnaire filled by his/her local ophthalmologist and mail it to us. In spite of our best efforts we could not obtain additional information on 14 eyes with less than 6 months follow up.
A standard surgical technique, essentially similar to that described by Kenyon et al, was followed in all patients, with a few minor modifications. All surgeries were performed using an operating microscope and peribulbar anaesthesia, except in a 9-year-old patient in whom the surgery was performed under general anaesthesia.
| Surgical Technique|| |
A wire speculum was used to separate the lids. A superior rectus bridle suture was inserted using 4-0 black silk. The suture was used to abduct the eye maximally (assume nasal pterygium. [Figure - 1], by clipping it to the drapes adjacent to the lateral canthus, after passing it under the arm of the wire speculum. A small incision was made in the conjunctiva just medial to the head of the pterygium, avoiding the obviously altered conjunctiva on the head of the pterygium. Beginning here, the conjunctiva was progressively dissected from the body of the pterygium, towards the caruncle, using Westcott scissors. Care was taken to release only the conjunctiva, and this was achieved by tenting up the dissected conjunctiva and snipping the taut adhesions to the subconjunctival tissue. The process was completed towards the upper fornix, caruncle and lower fornix in the shape of a triangle with its apex at the limbus, avoiding any conjunctival button-holing. The head of the pterygium was left attached to the cornea and served as a third hand for the surgeon, enabling easier dissection of the conjunctiva [Figure - 2].
The corneal epithelium 2 mm ahead of the head of the pterygium was scraped off with a hockey-stick knife (Grieshaber, Switzerland). This exposed the altered epithelium just adjacent to the head of the pterygium which was thickened and more firmly attached to the underlying cornea. The hockey-stick knife was used to elevate this thickened epithelium off the underlying cornea. Once this plane was defined, the pterygium head was easily avulsed using a combination of blunt dissection and traction. Residual fibrous tissue on the cornea was removed by sharp dissection with a No. 15 Bard-Parker blade. In primary pterygia, a cotton bud was used to elevate the body of the pterygium off the sclera. In recurrent pterygia, a combination of blunt and sharp dissection was used to remove the adherent fibrovascular tissue from the scleral surface. Especially in recurrent pterygia, extreme care was taken to avoid damage to the medial rectus muscle. In these lesions extreme medial dissection was avoided as the vascular caruncule is often dragged towards the cornea by the cicatricial process and damage to this tissue results in extensive bleeding. The body of the pterygium with the involved Tenon's capsule and cicatrix was then excised, taking care to ensure the safety of the underlying medial rectus muscle and the overlying conjunctiva. The abnormal tissue at the limbal end of the pterygium was aggressively resected, often extending about 2-3 mm beyond the visible extent of the pterygium to avoid leaving behind any scaffold for a later recurrence and to have a good bed for placement of the graft.
The size of the conjunctival graft required to resurface the exposed scleral surface was determined using Castroviejo calipers in 3 directions - extent across the limbus, maximum circumferential extent of the bed, and maximum distance from the limbus. This enabled the harvested graft to fit precisely in the bed. Careful hemostasis of the exposed scleral surface was done using wet-field cautery. Extensive blanching of the scleral surface was avoided. The limbus was smoothened using a stroking motion with the edge of the hockey-stick knife held perpendicular to the limbal. The bridle suture was used to rotate the globe downwards exposing the superior limbus and conjunctival surface. The measured dimensions were marked onto the superotemporal conjunctiva using several cautery spots [Figure - 3]. Using a Pierse-Hoskins forceps and Westcott scissors, the graft was excised starting at the forniceal end. Care was taken to obtain as thin a graft as possible without button-holing. Once the limbus was reached, the graft was flipped over onto the cornea and the tenon's attachments at the limbus were meticulously dissected. The flap was then excised using a Vannas scissors, taking care to include the limbal tissue.
After excision, the conjunctival-limbal graft was slid onto the cornea. Without lifting the tissue off the cornea, it was rotated and moved onto its scleral bed with fine non-toothed forceps. A limbus-limbus orientation was maintained. This helped to avoid inadvertent scrolling of the graft with resultant inversion of the surfaces. The graft was smoothened out in its bed taking care to avoid any folding of the edges. The eye was again abducted and the position of the graft was secured using interrupted 10-0 nylon sutures [Figure - 4]. The four corners of the graft were anchored with episcleral bites to maintain position. The medial edge of the graft was sutured with 2-4 additional sutures, preferably including episclera. No sutures were placed on the limbal side of the graft. The superior rectus bridle suture was removed and the donor area was covered by pulling the forniceal conjunctiva forward and anchoring
it to the limbal episcleral tissue with 2 interrupted 10-0 nylon sutures. No undermining of the superior conjunctiva was performed. 0.5cc dexamethasone was injected subconjunctivally at the conclusion of the procedure and the eye was patched firmly with antibiotic eye ointment.
Postoperatively, topical betamethasone eye drops were used every 2 hours for the first operative week and then tapered over the next 5-6 weeks. Antibiotic ointment was used 3 times daily for the first 2 weeks. Any retained sutures were removed at 6 weeks. A recurrence was defined as fibrovascular tissue crossing the corneoscleral limbus onto clear cornea in the area of previous pterygium excision. As both asymptomatic recurrences in this series were detected on routine examinations, the time to recurrence was calculated as the average of the last two follow-up visits. Statistical analyses were carried out using the SPSS statistical package. Continuous data were analysed using the Student's t-test and chi-square test and categorical data by Fisher's exact test.
| Results|| |
Of the 51 patients analysed, 38 (74.5%) were men and 13 (25.4%) were women. The mean age of the study population was 42.7±14.5 years (9,74 years). 29 (56.9%) of the patients were ≤ 40 years of age. The postoperative follow up of the 53 eyes ranged from 1.5 to 43 months (18.9±12.1 months). 37 (69.8%) eyes had a follow up of greater than 1 year, while 2 (3.8%) eyes had follow up between 6 months and 1 year. 14 (26.4%) eyes had a follow up of less than 6 months; the average follow up in this group was 2.9 ± 1.6 months (range 1.5 to 5.5 months). When this group of patients was compared with those having a follow up greater than 6 months, no statistically significant difference was found in the preoperative, intraoperative, and postoperative parameters [Table - 1].
The pterygium was present in 32 (60.4%) right eyes and 21 (39.6%) left eyes. 2 patients had bilateral pterygia. 36 (67.9%) eyes had primary pterygia, while 17 (32.1%) had recurrent pterygia. The average number of excisions per eye in the latter group was 1.4 ± 0.6, ranging from 1-3 procedures. In one patient with a recurrent pterygium, argon laser photocoagulation and mitomycin-C drops were used as adjunctive therapy in the postoperative period. 46 (86.8%) eyes had pterygia that extended at least midway between the limbus and the pupillary center. The pterygium was nasal in 46 (86.8%) eyes, temporal in 4 (7.5%) eyes and both nasal and temporal in 3 (5.7%) eyes. In all 53 eyes, the pterygium was pink and fleshy with a corneal haze at the head of the pterygium suggesting a progressive lesion. The extent of vascularisation was mild in 13 (24.5%) eyes, moderate in 38 (71.7%) eyes, and severe in 2 (3.8%) eyes, based on a subjective assessment by the operating surgeon. The presence of a Stocker's line at the head of the pterygium was observed in only 7 (13.2%) eyes.
One patient with a recurrent temporal pterygium had restriction of elevation with involvement of the
lateral and inferior recti and associated symblepharon. Adduction was restricted in another patient with a temporal pterygium. No movement restriction was seen in the remaining eyes.
Indications for surgery were visual impairment in 22 (41.5%) patients, and poor cosmesis in 31 (58.5%) patients. The conjunctival-limbal graft was obtained from the superotemporal quadrant in 49 (92.5%) eyes and from the superonasal quadrant in 4 (7.5%) eyes with temporal pterygia. In 2 eyes with both nasal and temporal pterygia, the obtained graft was appropriately divided between the two recipient sites. The smallest graft used was 5x4 mm while the largest graft measured 12x10 mm.
No significant intraoperative complications were noted in this series except for a button-holing of the conjunctival graft in one patient. After placement in the bed, the button-hole was repaired with one 10-0 nylon suture which included the underlying episclera. Most grafts demonstrated moderate edema in the first 2 weeks with accumulation of a serous yellow-tinged fluid, which resolved spontaneously. A corneal dellen was noted in one eye in the first postoperative week secondary to the graft edema which resolved on treatment with antibiotic ointment and pressure patching. In 2 eyes, sutures cut through with retraction of the conjunctiva at the graft-host junction. No active treatment was instituted and the exposed area epithelialized adequately on follow up without compromising surgical or cosmetic results. The upper lid developed giant papillary conjunctivitis due to exposed sutures in one eye which resolved with suture removal. At last follow up 23 (43.4%) eyes had an improvement in the best-corrected visual acuity ranging from 1 to 5 Snellen lines. In 28 (52.8%) eyes the best-corrected visual acuity was maintained, while it was reduced in 2 (3.8%) eyes. This was attributed to progression of cataract in a 52-year-old patient over 2 years of follow up and anterior ischemic optic neuropathy in a 63-year-old diabetic patient who developed sudden painless drastic decrease in vision, 1 month after pterygium surgery.
In the 2 eyes with motility restriction, surgery was successful in restoring extraocular movements. None of the eyes developed scarring or loss of mobility of the conjunctiva or corneal vascularization at the donor site. No sight-threatening complications were encountered.
Recurrence was noted in 2 (3.8%) eyes at 3.5 months and 9.2 months. Both recurrences were across-the-graft, asymptomatic and were detected on routine follow-up examinations. Both patients were 40 years or younger in age and had primary pterygium.
Satisfactory postoperative cosmesis [Figure - 5] was achieved in all eyes and this was subjectively graded by the patient as excellent in 27 (75%) eyes, good in 4 (11.1%) eyes, and fair in 5 (13.9%) eyes (this information was not available for 17 eyes).
| Discussion|| |
While the definitive management of a pterygium is surgical, the ideal adjunctive procedure is still to be determined. Mitomycin-C appears to be tolerated better in low doses and studies using this approach have reported a lower incidence of serious side effects. [12, 15, 16] However, an optimal dosage which decreases toxidty without reducing efficacy is still to be determined. A recently reported prospective study using low-dose mitomycin-C (0.2 mg/ml twice daily for 5 days), had a recurrence rate of 38% (9 of 24 eyes), with a mean follow up of 12.3 months, in patients with primary pterygia. The study did not report any scleral complications over the follow-up period, although one patient discontinued therapy after 3 days due to disabling pain, blepharospasm and photophobia. The symptoms persisted for 3 weeks, and the pterygium ultimately recurred. With a view to decreasing complications, the intraoperative use of mitomycin-C (0.02% for 5 minutes) has also been reported. Complications possibly due to mitomycin-C usage have been reported up to 3 years after treatment.
After the initial report by Kenyon et al (1985) describing the success of conjunctival autografting following pterygium excision, other authors have largely failed to achieve the same success rate [7, 9, 17, 19- 25] [Table - 2]. Simona et al reported a recurrence rate of 35% after such surgery in 14 eyes (13 primary; 1 recurrent) and advocated that the procedure should not be used as a standard primary surgical procedure for pterygium.
The wide range of recurrence rates reported has been attributed to various study differences including methodology (prospective/retrospective), patient characteristics (race, age), nature of pterygium (advanced/ inflamed /recurrent /progressive/ atrophic), geographic area of domicile, number of patients studied, definition of recurrence, duration of follow up and loss to follow up, surgical technique and surgeon's experience. On reviewing the published literature we feel that the surgical technique could probably be the single most important factor influencing recurrence. The meticulousness with which the limbal tissue is included in the autograft, in our opinion, determines the success of the procedure.
As seen in [Table - 2], three authors (Kenyon, Koch and Guler) have specifically described the inclusion of limbal tissue in the graft and have low recurrence rates.,, Among the other authors who have used free conjunctival grafts the only large series with comparable recurrence rates is that of Allan. The importance of limbal transplantation in ensuring low recurrence rates has also been stressed by Figueiredo et al.
The importance of the limbal stem cell in this condition is highlighted by the work of Dushku et al. They used immunohistochemical techniques to demonstrate altered limbal basal cells invading normal cornea at the advancing edge of the pterygium. A pterygium also exhibits features seen in limbal stem cell deficiency (SCD) states, described by Tseng; stromal inflammation, corneal vascularisation and conjunctivalization. The chronic epithelial defect which is also a hallmark of SCD is probably not seen here as the pterygium represents a state of localized SCD. Based on the above hypothesis, Kwok and Coroneo described a model for pterygium formation. The model predicts the clinically observed 'wing-shape' of the pterygium well, lending further support to localized limbal SCD as the putative cause of pterygium formation. The authors also mention that scattered light incident at the temporal limbus is focussed at the nasal limbus with a peak intensity >20 times, thus damaging the nasal basal limbal stem cells and explaining the observed preponderance of nasal pteiygia.
Our reported recurrence rate of 3.8% (2 of 53 eyes) probably results from our surgical technique of including the limbal tissue in the autograft. The recurrence rate is encouraging considering the strict definition of recurrence used and the high-risk population of Indian eyes with an average patient age of 42.7 years. The study group also included 17 (32.1%) recurrent pterygia and the pterygia were moderately advanced in 46 (86.8%) eyes with features of inflammation and progressive growth in 40 (75.5%) eyes. Other details of the surgical technique that are important are the retention of conjunctiva over the body of the pterygium so that a smaller graft is required, and the aggressive removal of subconjunctival tissue at the limbus to enable a proper placement of the graft. An adequately sized and shaped graft that fits well in the host bed is also important. Shaw describes a technique of using a paper template to achieve this, but by marking the conjunctiva in 3 axes as mentioned earlier, a similar result is obtained. The graft is dissected as thin as possible avoiding button-holing. As the excised stem cells are relocated to another area along the limbal perimeter, with no effective loss of the cells barring possible surgical damage, the procedure is quite safe.
None of the donor sites in this study developed vascularisation of the cornea or conjunctival fibrosis at the donor site, though subconjunctival fibrosis has been reported following conjunctival autografts. In both the patients reported by Vrabec et al the graft bed was allowed to heal primarily following the excision of large grafts. We believe that our technique of resurfacing the donor site with the superior forniceal conjunctiva helps avoid this complication. The use of infiltration anaesthesia is also important as the longer duration of the procedure can be comfortably tackled without compromising the surgical technique.
One of the patients with a recurrence in this series had both nasal and temporal primary pterygia and it is possible that he had more widespread limbal stem cell involvement than was evident clinically. It is also possible that inadequate stem cell transfer was achieved during surgery resulting in the recurrence. The second patient had a primary nasal pterygium and a small graft of 5x5 mm was used at surgery. This was one of the early surgeries in this series and it is possible that enough limbal tissue was not included in the graft.
The other eyes had good postoperative cosmesis and the 2 patients who had movement restriction had good restoration of extraocular movements after the surgery. No significant intraoperative or postoperative complications were encountered and there were no sight-threatening complications. Technically the procedure is straightforward and requires no extra surgical skills or equipment and does not require postoperative or intraoperative use of potentially toxic medications for an essentially benign condition.
Visual acuity improved or was maintained at the preoperative level in 51 (96.2%) eyes. In the 2 patients in whom postoperative visual acuity decreased, the causes were not related to the surgical procedure. 39 (73.6%) eyes in this study have a follow up at least 6 months and 37 (69.8%) eyes have a follow up of 1 year or more. It has been reported that 97% of recurrences develop during the first year after surgery. In spite of concerted efforts by mail, and telephone where possible, we could not improve upon the follow up. This however, is a problem common to all retrospective studies and in a recent study by Figueiredo et al, only 38 (60.3%) of 63 eyes achieved a follow up greater than 6 months. We compared patients who had less than 6 months follow up with those who had greater than 6 months follow up but could find no statistically significant differences in the preoperative, intraoperative or postoperative factors tested. The fact that both recurrences occurred in patients aged 40 years or younger also corroborates earlier reports of increased recurrence rates in younger patients.,
In summary, we review the recurrence rates for pterygium excision and conjunctival autografting reported in the literature. We also report a recurrence rate of 3.8% (2 of 53 eyes) in our series and stress the importance of a surgical technique which includes limbal tissue in the conjunctival graft. The success rate in this series of high-risk Byes is encouraging, in spite of the limitations of a retrospective study design, and we recommend conjunctival-limbal autografting as the procedure of choice for the Surgical management of both primary and recurrent pterygia in Indian eyes.
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[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5]
[Table - 1], [Table - 2]