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Experience with Pterygium Surgery and the Feasibility of Cultivated Limbal Stem Cell Harvesting for Recurrent Pterygium

By Dr.Prabhakar

Dr.Prabhakar is an Associate Professor in Ophthalmology department at JSS Medical College and Hospital, Mysore. Dr. Prabhakar has 25 years of professional experience and one of the leading corneal experts and a skilled corneal surgeon.

Our experience with pterygium surgery

Progressive pterygium is observed frequently in young and middle aged individuals who have more potential for recurrence after the excision than atrophic pterygium. It is clinically constituted by the proliferation of fibrovascular components apparently emanating from the medial canthus invading towards the cornea. The disease is multifactorial, mostly prevalent in field workers and travelers exposed to various atmospheric exogenous irritants. Ultra violet disruption of the limbal stem cells and angiogenesis probably play a role in pterygium development. Hence, there is failure of anatomical and physiological barrier function at the limbal girdle. Therefore, the importance of pterygium management lies in avoiding the recurrence, loss of vision, frequent inflammations and infections, more so in preserving the anatomical limbal ring integrity for cosmetical purposes.

A total of 101 eyes were investigated in a retrospective comparative study conducted in our Hospital that was followed-up for 18 months. 66 eyes received intra operative application of 0.04% Mitomycin-C and 35 eyes underwent conjunctival autografting. Scleral thinning in one patient noted with Mitomycin-C group and graft retraction occurred in another patient in the conjunctival autograft group. There were four recurrences (6.1%) in the first group and one recurrence (1.9%) in the second group.

In another prospective study of safety profile and complications following Limbal conjunctival autograft for primary pterygium included a total of 71 eyes of 68 patients. There were 35 (51%) male and 33 (49%) female patients with a mean age of 36.9 (range 19 to 75 years) recruited in the study. 39 (55%) left eyes had pterygium compared to 32 (45%) in the right eye. No recurrences encountered during 18 months of follow-up. The study demonstrated limbal conjunctival graft efficacy in terms of complete success rates with no recurrences.

The factors implicated in recurrence are younger age, presence of residual pterygial fibrablasts, inadvertent tissue manipulation, persistent post-operative inflammation and sutures. Pre and post operative use of topical steroids reduced the inflammation and bleeding tendencies during surgery. Careful smooth dissection and gentle handling of tissues with no cauterization, dissection of thin superficial conjunctiva up to its insertion that included the Limbal girdle of Volks (Tenons capsule excluded) that contains stem cells is utmost important in preventing the recurrences. Other factors that might contribute to the lower recurrence rates might be use of fibrin glue in place of the sutures.1 Despite the adoption of all controlled measures, recurrences do occur in some young patients. Therefore it may be prudent to evaluate the limbal stem cell density population pre-operatively in all patients to rule out pre-existing limbal stem cell deficiency (LSCD).

Need for cultivated limbal stem cell transplantation

Autologus limbal conjunctival transplantation showed better acceptable success rates than intraoperative use of Mitomycin-C.2 Unfortunately, scleral necrosis and dry eye cases reported with Mitomycin-C alerted the surgeon regarding the ocular safety of the anti-mitotic drugs. Cultivated conjunctival sheet transplantation for pterygium yielded 22.7% recurrence rate, which is still higher.3 The drawback of autologus limbal conjunctival transplantation may lead to iatrogenic LSCD in the donor's eye, especially when dealing with recurrent pterygium and chemical burns, where the need for larger grafts arise.4 Another disadvantage is the loss of superior limbal anatomy for construction of filtering bleb, in case the patient develops glaucoma in future.

The advantages of cultivated limbal epithelial stem cell transplantation is very minimal excision of the limbal conjunctiva from the donor's eye, thus preventing iatrogenic LSCD and simultaneously preserving the native limbal stem cell population. The limitations of dissecting larger limbal conjunctiva can undoubtedly overcome by cultivated transplant sheet for transplantation. Hence, the feasibility for harvesting autologus limbal epithelial stem cells in recurrent pterygium and unilateral or bilateral ocular surface disorders is justified.

References

  1. Miranda-Rollón MD, Pérez-González LE, Sentieri-Omarrementería A, Martínez-Rodríguez R, Parente-Hernández B, Junceda-Moreno J. [Pterygium surgery: comparative study of conjunctival autograft with suture versus fibrin adhesive]. Arch Soc Esp Oftalmol2009;84:179-84.
  2. Young AL, Leung GY, Wong AK, Cheng LL, Lam DS. A randomised trial comparing 0.02% mitomycin C and limbal conjunctival autograft after excision of primary pterygium. Br J Ophthalmol2004;88:995-7.
  3. Ang LP, Tan DT, Cajucom-Uy H, Beuerman RW. Autologous cultivated conjunctival transplantation for pterygium surgery. Am J Ophthalmol2005;139:611-9.
  4. Sanghamitra Burman, Virender Sangwan. Cultivated limbal stem cell transplantation for ocular surface reconstruction. Clin Ophthalmol2008;2:489–502.

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