- Email: [email protected]
Conjunctival rotation autograft for pterygium
Conjunctival Rotation Autograft for Pterygium An Alternative to Conjunctival Autografting Aliza Jap, FRCS(G), Cordelia Chan, FRCS(Ed), Li Lim, FRCS(Ed), Donald T. H. Tan, FRCS(G) Objective: To determine the safety and efficacy of conjunctival rotation autografting (CRA) as an alternative to conventional conjunctival autograft after pterygium excision. Design: Prospective noncomparative case series. Participants: Consecutive patients seen at the Pterygium Clinic of the Singapore National Eye Centre who were thought to be unsuitable for conventional conjunctival autografting underwent a modified surgical procedure, which the authors describe as CRA. There were 51 rotation autografts performed on 45 eyes of 43 patients. Intervention: In this procedure, the underlying fibrovascular pterygium tissue was removed and the original epithelium (with minimal subepithelial tissue included) replaced over the bare sclera with a 180° rotation. Surgeries were performed by one surgeon (DT) from April 1995 to May 1996. Main Outcome Measure: Pterygium recurrence and complications of CRA were measured. Results: The mean follow-up time was 12 months (range, 2–22 months). There were 46 primary and 5 recurrent pterygia. The indications for CRA were combined cataract and pterygium surgery (39.2%), double pterygia (31.4%), the need to preserve the superior conjunctiva (21.6%), and superior conjunctival scarring (7.8%). There were two recurrences (4% recurrence rate), one occurring at 4 months and the other occurring at 7 months after surgery. No significant complications were encountered. However, 50% of the grafts remained mildly injected for more than 3 months, and some remained injected for up to 13 months after surgery (average of 4 months). Pigmentary changes were also noted in six grafts (12%). Conclusion: Conjunctival rotation autografting is a useful technique of conjunctival grafting in cases in which it is not possible or desirable to use the superior conjunctiva as a donor source. Ophthalmology 1999;106:67–71 Primary pterygium is believed to be a consequence of ultraviolet-induced damage with subsequent elastoid degeneration of the subepithelial connective tissue.1– 4 In Singapore, which lies just north of the equator within the “pterygium belt,” there is a high prevalence of pterygium, and within the Singapore National Eye Centre, pterygium excision is the most common surgical procedure after cataract extraction. Because the complications associated with mitomycin C and beta-irradiation are thought to be unacceptable by most surgeons at our center, bare sclera (BS) excision and conjunctival autografts (CGs) are the main procedures performed. The technique of conjunctival autografting has been shown to be an effective method of preventing recurrences after excision of advanced and recurrent pterygium,5,6 and we recently concluded a prospective, randomized, controlled pterygium surgery
Originally received: March 10, 1998. Revision accepted: July 9, 1998. Manuscript no. 98125. From Singapore National Eye Centre, Singapore. Presented as a poster at the Association for Research in Vision and Ophthalmology annual meeting, Fort Lauderdale, Florida, May 1997. Reprint requests to Donald T. H. Tan, FRCS(G), Singapore National Eye Centre, 11 Third Hospital Avenue, Singapore 168751.
trial comparing this with bare sclera excision.7 In this study, conjunctival autografting was found to be extremely effective in reducing pterygium recurrence, with a 1-year recurrence rate of 1.6% in primary pterygium as opposed to BS excision, which achieved a 63% recurrence rate. Although our results showed that conjunctival autografting is safe and effective, there are occasions when it is not possible to use the superior bulbar conjunctiva as a donor source. The inferior bulbar conjunctiva is not a good donor site because it is technically more difficult to obtain a large, thin graft from this area, and we have anecdotal evidence of several cases of symblepharon formation occurring at the inferior donor site. In such cases, and if obtaining conjunctiva from the opposite eye is contraindicated or undesirable, we suggest that the conjunctival epithelium overlying the pterygium may be used instead in a modification of the conventional autograft, which we describe as a conjunctival rotation autografting (CRA) procedure. CRA involves dissection and preservation of the conjunctival epithelium overlying the pterygium, removal of underlying fibrovascular pterygium tissue, and replacement of the original epithelial sheet over the BS defect, but with a 180° rotation, so that the abnormal epithelial head of the pterygium is now away from the limbus.
67
Ophthalmology Volume 106, Number 1, January 1999
A
B Figure 1. A, the area of conjunctival epithelium to be harvested is outlined by the black dotted line. “A” represents the edge of the graft nearest the pterygium head, and “B” the edge nearest the canthus. B, the epithelial layer (with minimal subepithelial tissue) is dissected free, taking care not to include the underlying fibrovascular pterygium tissue. C, this epithelial layer is replaced with a 180° reorientation onto the bared sclera bed (epithelial surface up).
A
B
Figure 2. A, patient with pterygia of the nasal and temporal aspect— before surgery. B, same patient 2 months after conjunctival rotation autografting.
68
Jap et al 䡠 Conjunctival Rotation Autograft for Pterygium We report on a consecutive series of 51 CRAs performed by one surgeon for cases of pterygia in which a conventional CG was contraindicated or not possible.
vessels and the presence of fibrovascular tissue originating from the conjunctiva. The graft was arbitrarily considered to be injected if it was noticeably red on general naked eye inspection. Pigmentary changes were similarly evaluated subjectively.
Methods All consecutive cases of pterygia seen at the Pterygium Clinic of the Singapore National Eye Centre requiring excision and that were not suitable for conventional CG were offered CRA. The clinical trial protocol was approved by the Singapore National Eye Centre ethics committee, and informed patient consent was obtained before surgery. Before surgery, the best-corrected Snellen visual acuity, intraocular pressure (by Goldmann applanation tonometry), and details of slit-lamp and fundus examinations were recorded. A system of grading pterygia according to their morphology has been developed for use in pterygium studies in this center.7 This classification is based on the relative translucency of pterygium tissue overlying the sclera as seen at the slit lamp, with the premise that loss of transparency is related to increased thickness of the fibrovascular component of the pterygium: ●
●
●
Grade T1 (atrophic)—a pterygium in which episcleral vessels underlying the body of the pterygium are clearly distinguished and unobscured. Grade T3 (fleshy)—a thick, fleshy pterygium in which episcleral vessels underlying the body of the pterygium are totally obscured. All other pterygia that do not fall into these two categories (i.e., episcleral vessel details seen indistinctly or partially obscured) fall into grade T2 (intermediate).
All the operations were performed by one surgeon (DT) during the period from April 1995 to May 1996.
Surgical Procedure of Conjunctival Rotation Autografting Under retrobulbar or peribulbar block, epithelium overlying the pterygium was carefully dissected free using a superficial dissection technique to avoid obtaining underlying fibrovascular pterygium tissue (Figs 1A, B). It was, however, not possible to dissect the epithelium without inclusion of some subepithelial tissue, as substantia propria is densely adherent to epithelial basement membrane. This epithelial sheet was laid aside, and the fibrovascular pterygium tissue was then dissected off from the sclera and cornea, with care being taken to achieve a smooth avascular bed. The original epithelial sheet was then replaced with a 180° reorientation (Fig 1C). The graft was sutured in place with 8 – 0 virgin silk. This procedure was combined with additional ocular surgery in 31 eyes. At the end of surgery, all patients received a subconjunctival injection of 20 mg gentamicin and 2 mg dexamethasone in the inferior fornix. After surgery, all the patients received a standard regimen of a combination chloramphenicol and 0.1% dexamethasone eyedrop starting with every 3 hours for 1 week and decreasing to four times a day for the next 3 weeks. It was then discontinued. Patients were reviewed at 1 day, 1 week, 1 month, 3 months, 6 months, and 1 year after surgery. At each visit, in addition to best-corrected Snellen visual acuity and intraocular pressure, the presence or absence of recurrence, injection, pigmentary changes, as well as other complications, was noted. Recurrence was defined as the presence of fibrovascular reencroachment extending beyond the surgical limbus at any time during the study period. This was distinguished from graft slippage across the limbus by the definite radial orientation of pterygium
Results There were 51 CRAs performed on 45 eyes of 43 patients. Of the 43 patients, 31 (72%) were males. The mean age of the patients was 65 years, with a range of 35 to 87 years. Most of the patients were Chinese (86%), with 9% Malays, 2.5% Indians, and 2.5% of other races. Mean follow-up was 12 months with a range of 2 to 22 months. The majority (90%) were primary pterygia with most (70%) occurring at the nasal aspect. Among the primary pterygia, there were 27% grade T1, 42% grade T2, and 31% grade T3 pterygia. All of the recurrent pterygia were grade T3. The inclusion criterion for CRA in this series was the relative contraindication or inability to harvest conjunctiva from the superior bulbar conjunctiva in patients undergoing pterygium excision. The main indication for CRA was combined pterygium excision and cataract extraction with IOL implantation (20 cases, 39.2%), in which conventional superior conjunctival harvesting would have resulted in excessive conjunctival exposure adjacent to the limbal cataract wound. Simultaneous excision of nasal and temporal pterygium was the next most common indication (16 cases, 31.4%) (Figs 2A, B). In these cases, the extensive baring of superior bulbar conjunctiva required to obtain grafts large enough to cover both nasal and temporal BS areas was deemed unacceptable. In 11 cases (21.6%), surgical dissection of superior conjunctiva was contraindicated because of pre-existing glaucoma (two cases) (Figs 3A–C), glaucoma suspect cases (eight cases), and one one-eyed patient. Finally, in four cases (7.8%), pre-existing superior conjunctival scarring (three due to previous ocular surgery and one due to trachomatous scarring) was a contraindication for superior conjunctival harvesting (Table 1). Two recurrences (4%) were noted within the study period, one occurring at 4 months and the other occurring at 7 months after surgery. Both of these were grade T3 primary pterygia. There was one case of dellen and one case of epithelial inclusion cyst, both of which resolved spontaneously. No other significant complications were encountered, with the exception of persistent graft injection or pigmentation. Of the 50 grafts for which a detailed description of graft appearance was available, 25 (50%) of the grafts remained mildly injected at 3 months (Fig 4). In some of these eyes, this injection was noted up to 13 months after surgery, with an average duration of 4 months. Pigmentary changes were also seen in six grafts (12%).
Discussion The concept of a rotational autograft to reduce pterygium recurrence is not new. A “rotated island graft” was described by Spaeth8 in the 1920s. This technique avoided the loss of conjunctiva, but the fibrovascular subconjunctival tissue was not removed; therefore, cosmesis was poor with slow wound healing, and the procedure never became popular. A better result could be obtained, however, when the underlying subconjunctival tissue was excised before the pterygium epithelium was rotated. Our primary aim of rotating the graft 180° in a CRA was to displace the epithelium at the pterygium head away from
69
Ophthalmology Volume 106, Number 1, January 1999
A Figure 4. Conjunctival rotation autografting (CRA) in a patient who underwent simultaneous cataract extraction with intraocular lens implant. At 5 months after surgery, the CRA site remains injected.
B
C Figure 3. A, a pterygium in a patient with coexisting glaucoma. B, 9 days after conjunctival rotation autografting surgery. C, 17 months after surgery.
the limbus and replace it with relatively normal conjunctiva from the canthal area. This is based on the unsubstantiated, but not entirely unreasonable, assumption that pterygium recurrence may be higher if the abnormal epithelium at the head of the pterygium is replaced at the limbus. However, we are not certain what role graft rotation plays in the prevention of pterygium recurrence. A randomized trial
70
comparing graft rotation with no rotation would be required to address this issue. This study shows the safety and efficacy of our technique of CRA, as performed by one surgeon with considerable experience with conventional CG. Certainly, the recurrence rate of 4% in this series is comparable to recurrence rates in other studies on CG, which range from 2% to 39%, and to our previous clinical trial.5–7,9,10 Both of our recurrences occurred with primary fleshy pterygia of grade T3. Pterygium morphology, as described by this grading system was shown in our previous study to be useful in predicting recurrence after BS excision.7 In that study, the poorest 12-month cumulative survival rate was for grade T3 pterygia (0.15) compared to 0.64 and 0.38 for grades T1 and T2, respectively. Although the CG study was conducted before this CRA series and therefore may not be directly comparable, it should be noted that patients in both studies were recruited from the same pterygium clinic and that the same surgeon graded and performed all surgeries. Performing a CRA procedure is more technically demanding for several reasons. First, it may be difficult in some instances to cleanly separate the epithelium from underlying pterygium fibrovascular tissue, especially as overlapping conjunctival folds are present in some pterygia. Second, in conventional CG, a useful technique to reduce the effect of graft retraction is to oversize the graft in Table 1. Indications for CRA Indication
% of Cases (n ⴝ 51)
Combined with cataract extraction with IOL implantation Double pterygia excision (nasal and temporal) Preserve superior conjunctiva Superior conjunctival scarring
39.2 31.4 21.6 7.8
IOL ⫽ intraocular lens.
Jap et al 䡠 Conjunctival Rotation Autograft for Pterygium relation to the BS area. This is obviously not possible in the CRA procedure in which the defect is invariably larger than the original epithelial sheet because of graft shrinkage and retraction of the edges of the recipient bed. A CRA is also cosmetically less satisfactory than a CG. However, it allows for the preservation of conjunctiva elsewhere and is a viable alternative to CG in patients for whom a good cosmetic result is not a primary consideration. It has been proposed that pterygia arise as a result of a local limbal deficiency,11 possibly resulting from chronic ultraviolet-related damage to interpalpebral limbal stem cells. The success of CG has been attributed to the transfer of superior limbal stem cells to replace this limbal deficiency, suggesting that this procedure may in fact be a form of limbal graft, and it has therefore been advocated that proper limbal orientation of the donor graft to the host bed be maintained.6 Others also have described the use of limbal autografts for pterygium surgery as an alternative to CG.12,13 The success of CRA, however, questions the validity of this theory, as limbal orientation is not respected in this technique with apparently minimal effect on pterygium recurrence. This suggests that CG, be it a conventional autograft, a CRA, or a limbal autograft, prevents pterygium recurrence by an alternative mode of action. Under normal circumstances, it is assumed that healthy limbal tissue acts as a barrier to prevent subconjunctival tissue from invading the cornea. We hypothesize that in pterygium, this barrier is breached and that placement of unaffected conjunctiva (in the case of CRA, relatively normal conjunctiva from the canthal area) may perhaps result in the restoration of this barrier, be it physical or physiologic, preventing fibrovascular pterygium regrowth beneath the graft. Certainly, in cases of recurrence after a CG, pterygium tissue often recurs either around or at the edges of the graft where BS was exposed as a result of graft retraction. This barrier theory has previously been proposed by Youngson,14 who first noted the translimbal migration of corneal epithelium onto BS after simple pterygium excision. He suggested that this migration was the reason for pterygium recurrence. One may further hypothesize that graft conjunctiva may contain specific cytokine growth factors that are responsible for preventing fibroblastic pterygium regrowth, which histologically represents a hyperplastic fibrovascular scar as opposed to the histologic appearance of a primary pterygium.4 In summary, CRA appears to be a successful and safe alternative to CG, with a relatively low rate of pterygium
recurrence in this uncontrolled series. We advocate the use of CRA for cases of pterygium in which a conventional autograft is contraindicated or difficult. The apparent success of this procedure suggests that the transfer of limbal stem cells is not a primary reason for the success of conjunctival grafting in pterygium surgery.
References 1. Jaros PA, De Luise VP. Pingueculae and pterygia. Surv Ophthalmol 1988;33:41–9. 2. King JH Jr. The pterygium: brief review and evaluation of certain methods of treatment. Arch Ophthalmol 1950;44:854 – 69. 3. Guillermo P. Pterygium—Current concept of etiology and management. In: King JH Jr, McTigue JW, eds. The Cornea World Congress: Papers. Washington, DC: Butterworths, 1965:280 –91. 4. Abbott RL, ed. Surgical Intervention in Corneal and External Diseases. Orlando: Grune & Stratton, 1987;141–53. 5. Kenyon KR, Wagoner MD, Hettinger ME. Conjunctival autograft transplantation for advanced and recurrent pterygium. Ophthalmology 1985;92:1461–70. 6. Riordan–Eva P, Kielhorn I, Ficker LA, et al. Conjunctival autografting in the surgical management of pterygium. Eye 1993;7:634 – 8. 7. Tan DT, Chee SP, Dear KB, Lim AS. Effect of pterygium morphology on pterygium recurrence in a controlled trial comparing conjunctival autografting with bare sclera excision. Arch Ophthalmol 1997;115:1235– 40. 8. Spaeth ED. Rotated island graft operation for pterygium. Am J Ophthalmol 1926;9:649 –55. 9. Lewallen S. A randomized trial of conjunctival autografting for pterygium in the tropics. Ophthalmology 1989;96:1612– 4. 10. Chen PP, Ariyasu RG, Kaza V, et al. A randomized trial comparing mitomycin C and conjunctival autograft after excision of primary pterygium. Am J Ophthalmol 1995;120: 151– 60. 11. Tseng SCG. Concept and application of limbal stem cells. Eye 1989;3:141–57. 12. Kenyon KR, Tseng SCG. Limbal autograft transplantation for ocular surface disorders. Ophthalmology 1989;96:709 –22. 13. Shimazaki J, Yang HY, Tsubota K. Limbal autograft transplantation for recurrent and advanced pterygia. Ophthalmic Surg Lasers 1996;27:917–23. 14. Youngson RM. Recurrence of pterygium after excision. Br J Ophthalmol 1972;56:120 –5.
71
Originally received: March 10, 1998. Revision accepted: July 9, 1998. Manuscript no. 98125. From Singapore National Eye Centre, Singapore. Presented as a poster at the Association for Research in Vision and Ophthalmology annual meeting, Fort Lauderdale, Florida, May 1997. Reprint requests to Donald T. H. Tan, FRCS(G), Singapore National Eye Centre, 11 Third Hospital Avenue, Singapore 168751.
trial comparing this with bare sclera excision.7 In this study, conjunctival autografting was found to be extremely effective in reducing pterygium recurrence, with a 1-year recurrence rate of 1.6% in primary pterygium as opposed to BS excision, which achieved a 63% recurrence rate. Although our results showed that conjunctival autografting is safe and effective, there are occasions when it is not possible to use the superior bulbar conjunctiva as a donor source. The inferior bulbar conjunctiva is not a good donor site because it is technically more difficult to obtain a large, thin graft from this area, and we have anecdotal evidence of several cases of symblepharon formation occurring at the inferior donor site. In such cases, and if obtaining conjunctiva from the opposite eye is contraindicated or undesirable, we suggest that the conjunctival epithelium overlying the pterygium may be used instead in a modification of the conventional autograft, which we describe as a conjunctival rotation autografting (CRA) procedure. CRA involves dissection and preservation of the conjunctival epithelium overlying the pterygium, removal of underlying fibrovascular pterygium tissue, and replacement of the original epithelial sheet over the BS defect, but with a 180° rotation, so that the abnormal epithelial head of the pterygium is now away from the limbus.
67
Ophthalmology Volume 106, Number 1, January 1999
A
B Figure 1. A, the area of conjunctival epithelium to be harvested is outlined by the black dotted line. “A” represents the edge of the graft nearest the pterygium head, and “B” the edge nearest the canthus. B, the epithelial layer (with minimal subepithelial tissue) is dissected free, taking care not to include the underlying fibrovascular pterygium tissue. C, this epithelial layer is replaced with a 180° reorientation onto the bared sclera bed (epithelial surface up).
A
B
Figure 2. A, patient with pterygia of the nasal and temporal aspect— before surgery. B, same patient 2 months after conjunctival rotation autografting.
68
Jap et al 䡠 Conjunctival Rotation Autograft for Pterygium We report on a consecutive series of 51 CRAs performed by one surgeon for cases of pterygia in which a conventional CG was contraindicated or not possible.
vessels and the presence of fibrovascular tissue originating from the conjunctiva. The graft was arbitrarily considered to be injected if it was noticeably red on general naked eye inspection. Pigmentary changes were similarly evaluated subjectively.
Methods All consecutive cases of pterygia seen at the Pterygium Clinic of the Singapore National Eye Centre requiring excision and that were not suitable for conventional CG were offered CRA. The clinical trial protocol was approved by the Singapore National Eye Centre ethics committee, and informed patient consent was obtained before surgery. Before surgery, the best-corrected Snellen visual acuity, intraocular pressure (by Goldmann applanation tonometry), and details of slit-lamp and fundus examinations were recorded. A system of grading pterygia according to their morphology has been developed for use in pterygium studies in this center.7 This classification is based on the relative translucency of pterygium tissue overlying the sclera as seen at the slit lamp, with the premise that loss of transparency is related to increased thickness of the fibrovascular component of the pterygium: ●
●
●
Grade T1 (atrophic)—a pterygium in which episcleral vessels underlying the body of the pterygium are clearly distinguished and unobscured. Grade T3 (fleshy)—a thick, fleshy pterygium in which episcleral vessels underlying the body of the pterygium are totally obscured. All other pterygia that do not fall into these two categories (i.e., episcleral vessel details seen indistinctly or partially obscured) fall into grade T2 (intermediate).
All the operations were performed by one surgeon (DT) during the period from April 1995 to May 1996.
Surgical Procedure of Conjunctival Rotation Autografting Under retrobulbar or peribulbar block, epithelium overlying the pterygium was carefully dissected free using a superficial dissection technique to avoid obtaining underlying fibrovascular pterygium tissue (Figs 1A, B). It was, however, not possible to dissect the epithelium without inclusion of some subepithelial tissue, as substantia propria is densely adherent to epithelial basement membrane. This epithelial sheet was laid aside, and the fibrovascular pterygium tissue was then dissected off from the sclera and cornea, with care being taken to achieve a smooth avascular bed. The original epithelial sheet was then replaced with a 180° reorientation (Fig 1C). The graft was sutured in place with 8 – 0 virgin silk. This procedure was combined with additional ocular surgery in 31 eyes. At the end of surgery, all patients received a subconjunctival injection of 20 mg gentamicin and 2 mg dexamethasone in the inferior fornix. After surgery, all the patients received a standard regimen of a combination chloramphenicol and 0.1% dexamethasone eyedrop starting with every 3 hours for 1 week and decreasing to four times a day for the next 3 weeks. It was then discontinued. Patients were reviewed at 1 day, 1 week, 1 month, 3 months, 6 months, and 1 year after surgery. At each visit, in addition to best-corrected Snellen visual acuity and intraocular pressure, the presence or absence of recurrence, injection, pigmentary changes, as well as other complications, was noted. Recurrence was defined as the presence of fibrovascular reencroachment extending beyond the surgical limbus at any time during the study period. This was distinguished from graft slippage across the limbus by the definite radial orientation of pterygium
Results There were 51 CRAs performed on 45 eyes of 43 patients. Of the 43 patients, 31 (72%) were males. The mean age of the patients was 65 years, with a range of 35 to 87 years. Most of the patients were Chinese (86%), with 9% Malays, 2.5% Indians, and 2.5% of other races. Mean follow-up was 12 months with a range of 2 to 22 months. The majority (90%) were primary pterygia with most (70%) occurring at the nasal aspect. Among the primary pterygia, there were 27% grade T1, 42% grade T2, and 31% grade T3 pterygia. All of the recurrent pterygia were grade T3. The inclusion criterion for CRA in this series was the relative contraindication or inability to harvest conjunctiva from the superior bulbar conjunctiva in patients undergoing pterygium excision. The main indication for CRA was combined pterygium excision and cataract extraction with IOL implantation (20 cases, 39.2%), in which conventional superior conjunctival harvesting would have resulted in excessive conjunctival exposure adjacent to the limbal cataract wound. Simultaneous excision of nasal and temporal pterygium was the next most common indication (16 cases, 31.4%) (Figs 2A, B). In these cases, the extensive baring of superior bulbar conjunctiva required to obtain grafts large enough to cover both nasal and temporal BS areas was deemed unacceptable. In 11 cases (21.6%), surgical dissection of superior conjunctiva was contraindicated because of pre-existing glaucoma (two cases) (Figs 3A–C), glaucoma suspect cases (eight cases), and one one-eyed patient. Finally, in four cases (7.8%), pre-existing superior conjunctival scarring (three due to previous ocular surgery and one due to trachomatous scarring) was a contraindication for superior conjunctival harvesting (Table 1). Two recurrences (4%) were noted within the study period, one occurring at 4 months and the other occurring at 7 months after surgery. Both of these were grade T3 primary pterygia. There was one case of dellen and one case of epithelial inclusion cyst, both of which resolved spontaneously. No other significant complications were encountered, with the exception of persistent graft injection or pigmentation. Of the 50 grafts for which a detailed description of graft appearance was available, 25 (50%) of the grafts remained mildly injected at 3 months (Fig 4). In some of these eyes, this injection was noted up to 13 months after surgery, with an average duration of 4 months. Pigmentary changes were also seen in six grafts (12%).
Discussion The concept of a rotational autograft to reduce pterygium recurrence is not new. A “rotated island graft” was described by Spaeth8 in the 1920s. This technique avoided the loss of conjunctiva, but the fibrovascular subconjunctival tissue was not removed; therefore, cosmesis was poor with slow wound healing, and the procedure never became popular. A better result could be obtained, however, when the underlying subconjunctival tissue was excised before the pterygium epithelium was rotated. Our primary aim of rotating the graft 180° in a CRA was to displace the epithelium at the pterygium head away from
69
Ophthalmology Volume 106, Number 1, January 1999
A Figure 4. Conjunctival rotation autografting (CRA) in a patient who underwent simultaneous cataract extraction with intraocular lens implant. At 5 months after surgery, the CRA site remains injected.
B
C Figure 3. A, a pterygium in a patient with coexisting glaucoma. B, 9 days after conjunctival rotation autografting surgery. C, 17 months after surgery.
the limbus and replace it with relatively normal conjunctiva from the canthal area. This is based on the unsubstantiated, but not entirely unreasonable, assumption that pterygium recurrence may be higher if the abnormal epithelium at the head of the pterygium is replaced at the limbus. However, we are not certain what role graft rotation plays in the prevention of pterygium recurrence. A randomized trial
70
comparing graft rotation with no rotation would be required to address this issue. This study shows the safety and efficacy of our technique of CRA, as performed by one surgeon with considerable experience with conventional CG. Certainly, the recurrence rate of 4% in this series is comparable to recurrence rates in other studies on CG, which range from 2% to 39%, and to our previous clinical trial.5–7,9,10 Both of our recurrences occurred with primary fleshy pterygia of grade T3. Pterygium morphology, as described by this grading system was shown in our previous study to be useful in predicting recurrence after BS excision.7 In that study, the poorest 12-month cumulative survival rate was for grade T3 pterygia (0.15) compared to 0.64 and 0.38 for grades T1 and T2, respectively. Although the CG study was conducted before this CRA series and therefore may not be directly comparable, it should be noted that patients in both studies were recruited from the same pterygium clinic and that the same surgeon graded and performed all surgeries. Performing a CRA procedure is more technically demanding for several reasons. First, it may be difficult in some instances to cleanly separate the epithelium from underlying pterygium fibrovascular tissue, especially as overlapping conjunctival folds are present in some pterygia. Second, in conventional CG, a useful technique to reduce the effect of graft retraction is to oversize the graft in Table 1. Indications for CRA Indication
% of Cases (n ⴝ 51)
Combined with cataract extraction with IOL implantation Double pterygia excision (nasal and temporal) Preserve superior conjunctiva Superior conjunctival scarring
39.2 31.4 21.6 7.8
IOL ⫽ intraocular lens.
Jap et al 䡠 Conjunctival Rotation Autograft for Pterygium relation to the BS area. This is obviously not possible in the CRA procedure in which the defect is invariably larger than the original epithelial sheet because of graft shrinkage and retraction of the edges of the recipient bed. A CRA is also cosmetically less satisfactory than a CG. However, it allows for the preservation of conjunctiva elsewhere and is a viable alternative to CG in patients for whom a good cosmetic result is not a primary consideration. It has been proposed that pterygia arise as a result of a local limbal deficiency,11 possibly resulting from chronic ultraviolet-related damage to interpalpebral limbal stem cells. The success of CG has been attributed to the transfer of superior limbal stem cells to replace this limbal deficiency, suggesting that this procedure may in fact be a form of limbal graft, and it has therefore been advocated that proper limbal orientation of the donor graft to the host bed be maintained.6 Others also have described the use of limbal autografts for pterygium surgery as an alternative to CG.12,13 The success of CRA, however, questions the validity of this theory, as limbal orientation is not respected in this technique with apparently minimal effect on pterygium recurrence. This suggests that CG, be it a conventional autograft, a CRA, or a limbal autograft, prevents pterygium recurrence by an alternative mode of action. Under normal circumstances, it is assumed that healthy limbal tissue acts as a barrier to prevent subconjunctival tissue from invading the cornea. We hypothesize that in pterygium, this barrier is breached and that placement of unaffected conjunctiva (in the case of CRA, relatively normal conjunctiva from the canthal area) may perhaps result in the restoration of this barrier, be it physical or physiologic, preventing fibrovascular pterygium regrowth beneath the graft. Certainly, in cases of recurrence after a CG, pterygium tissue often recurs either around or at the edges of the graft where BS was exposed as a result of graft retraction. This barrier theory has previously been proposed by Youngson,14 who first noted the translimbal migration of corneal epithelium onto BS after simple pterygium excision. He suggested that this migration was the reason for pterygium recurrence. One may further hypothesize that graft conjunctiva may contain specific cytokine growth factors that are responsible for preventing fibroblastic pterygium regrowth, which histologically represents a hyperplastic fibrovascular scar as opposed to the histologic appearance of a primary pterygium.4 In summary, CRA appears to be a successful and safe alternative to CG, with a relatively low rate of pterygium
recurrence in this uncontrolled series. We advocate the use of CRA for cases of pterygium in which a conventional autograft is contraindicated or difficult. The apparent success of this procedure suggests that the transfer of limbal stem cells is not a primary reason for the success of conjunctival grafting in pterygium surgery.
References 1. Jaros PA, De Luise VP. Pingueculae and pterygia. Surv Ophthalmol 1988;33:41–9. 2. King JH Jr. The pterygium: brief review and evaluation of certain methods of treatment. Arch Ophthalmol 1950;44:854 – 69. 3. Guillermo P. Pterygium—Current concept of etiology and management. In: King JH Jr, McTigue JW, eds. The Cornea World Congress: Papers. Washington, DC: Butterworths, 1965:280 –91. 4. Abbott RL, ed. Surgical Intervention in Corneal and External Diseases. Orlando: Grune & Stratton, 1987;141–53. 5. Kenyon KR, Wagoner MD, Hettinger ME. Conjunctival autograft transplantation for advanced and recurrent pterygium. Ophthalmology 1985;92:1461–70. 6. Riordan–Eva P, Kielhorn I, Ficker LA, et al. Conjunctival autografting in the surgical management of pterygium. Eye 1993;7:634 – 8. 7. Tan DT, Chee SP, Dear KB, Lim AS. Effect of pterygium morphology on pterygium recurrence in a controlled trial comparing conjunctival autografting with bare sclera excision. Arch Ophthalmol 1997;115:1235– 40. 8. Spaeth ED. Rotated island graft operation for pterygium. Am J Ophthalmol 1926;9:649 –55. 9. Lewallen S. A randomized trial of conjunctival autografting for pterygium in the tropics. Ophthalmology 1989;96:1612– 4. 10. Chen PP, Ariyasu RG, Kaza V, et al. A randomized trial comparing mitomycin C and conjunctival autograft after excision of primary pterygium. Am J Ophthalmol 1995;120: 151– 60. 11. Tseng SCG. Concept and application of limbal stem cells. Eye 1989;3:141–57. 12. Kenyon KR, Tseng SCG. Limbal autograft transplantation for ocular surface disorders. Ophthalmology 1989;96:709 –22. 13. Shimazaki J, Yang HY, Tsubota K. Limbal autograft transplantation for recurrent and advanced pterygia. Ophthalmic Surg Lasers 1996;27:917–23. 14. Youngson RM. Recurrence of pterygium after excision. Br J Ophthalmol 1972;56:120 –5.
71