Multiple procedures have been advocated in the treatment of pterygium ranging from simple excision with bare sclera to the use of grafts to cover the sclera. Simple excision carries a high recurrence rate ranging from 24%-89%. The addition of mitomycin C (MMC) or the use of grafts has been reported to be effective in preventing recurrence. While the use of conjunctival autografts has resulted in better success rates, it is time consuming, technically difficult and inapplicable in cases with limbal disturbances.
Cryopreserved amniotic membrane with fibrin glue and intraoperative application of MMC also provides good success rates and can reduce patient pain and improve the surgical aesthetic outcome with a lower rate of recurrence. Therefore, this modality has been used as the preferred treatment for pterygium.
Pterygium Key Pre-Operative Points
Determine pterygium aggressiveness by passing a slit beam across the pterygium body to estimate the amount of fibrovascular growth sandwiched between the conjunctiva and the Tenon. The more aggressive the pterygium is, the more the semilunar fold is dragged, the more the caruncle is flattened, and the less likely the episcleral vessels are visible.
Pay attention and manage other ocular surface diseases that may cause “inflammation,” such as dry eye, allergy/atopy, or demodex blepharitis prior to surgery.
Cryopreserved Amniotic Membrane Allograft:
AMNIOGRAFT® from Bio-Tissue (1-888-296-8858). For primary pterygium use the 2.0 x 1.5 cm size (Catalog # AG-2015). For double headed pterygium use the 2.5 x 2.0 cm size (Catalog # AG-2520) or 3.5 x 3.5 cm size (Catalog # AG-3535)
Miomycin C (MMC)
Prepared by diluting lyophilized powder with Balanced Salt Solution (BSS). Make sure the concentration is correct. 0.02% – 0.04% MMC is equal to 0.2 – 0.4 mg/ml.
Use 7-0 Vicryl sutures
For sutureless surgery, use fibrin glue: TISSEEL from Baxter Biologics (1-877-TISSEEL) 2.0 mL (Catalog # 1501236) or Evicel from Ethicon from Johnson & Johnson (1-800-255-2500) 1 mL (NDC # 63713-390-11).
For surgery with sutures, 10-0 nylon and 8-0 Vicryl sutures are recommended.
Estimated surgery time: 20 minutes.
nsert a 15 mm solid blades Speculum (K1-5014 Katena), apply Epinephrine (1:1000) for hemostasis and 2% lidocaine gel (Astra Zeneca) for Topical Anesthesia P.S. Avoid peribulbar anesthesia which may distort the tissue plane
Place 7-0 Vicryl Traction Suture at the superior and inferior limbal sclera for adequate exposure and fixation of the globe
Excise pterygium head and body:
Use 0.12 forceps to pick up the conjunctiva in front of the semilunar fold (Fig. 1), and use scissors to make a conjunctival peritomy vertically. Then pick up the fibrovascular pterygium tissue toward the surgeon while using scissors to truncate it from the fornix. Without damaging the muscle, excise the Tenon from the sclera that is superior and inferior to the muscle. Remove the head and body of the pterygium from the cornea surface (Fig. 2).
Apply MMC (0.02% to 0.04%):
Cut thin strips from a Weckcel’s slant edges, soak them in the MMC solution, and apply approximately 2-3 sponges to subconjunctival fibrovascular tissue close to the fornix and above the tenon (Fig. 3). Before application, use a Q-tip to dry the bare sclera (Fig. 4). Then apply MMC strips for 2 min for mild, for 3 min for moderate, and 4 min for severe pterygium. Irrigate the contact surface with half a bottle of BSS after the incubation.
Identify & Seal the gap between the Conjunctiva and Tenon:
Use two 0.12 forceps: one to grab the conjunctival edge and the other for the underlying Tenon, to evaluate the extent of the gap, especially at the caruncle (Fig. 5A). This gap allows reinvasion (hemiation) of the residual fibrovascular tissue, giving rise to recurrence if left open.
Use 8-0 Vicryl running sutures for primary pterygium and 9-0 Nylon for recurrent pterygium when “sealing the gap” from the superior to the inferior fornix. The natural traction of the Tenon posteriorly facilitates the conjinctiva bending away from the sclera, which will reform the shape of the caruncle (Fig 5B).
Transplant Cryopreserved Amnion Graft with Fibrin Glue:
nitrocellulose paper. Lay it on the bare sclera with the sticky/stromal surface facing down. Flip one half of the graft up to cover the other half revealing the bare sclera.
Apply the fibrinogen oily/cloudy solution to the bare sclera and/or the stromal side of the graft. Next, apply the thrombin/watery/clear solution to the same area.
Using two 0.12 forceps to flip back the graft to re-cover the bare sclera. Stretch and flatten the graft with two forceps at different areas for a total of 45 sec before final smoothening by a muscle hook. Repeat the above steps to the other half of the membrane. Trim any excess membrane and fibrin glue from around the defect and then tuck the graft underneath the conjunctival edge and seal the conjunctiva over the graft with fibrin glue placed in between (Fig. 6).
Always check the adhesion strength at the edge of the graft by 0.12 forceps. If the graft detaches, do “touch up” by applying fibrin glue to the unsecured areas.
Excise pterygium head and body:
For recurrent pterygium, wait at least 6 months before re-operation. Use the surgical technique described for primary pterygium with the modification that the pterygium body removal should start at the limbal region. Carefully detach the head and body of the pterygium from the cornea and perilimbal bulbar sclera (to create bare sclera).
The first aim is to recess (but not resect) the entire fibrovascular tissue to the fornix (in a tension-free state). The second aim is to seal the gap between the conjunctiva and the Tenon using 9-0 Nylon running sutures. Intraoperative application of MMC is not mandatory. AMT can be performed as well.
Excise pterygium head and body:
For multi-recurrent pterygium with Motility Restriction, use same surgical technique as described for recurrent pterygium. However, if there is motility restriction, it is advisable to cover the muscle surface with a sheet of cryopreserved AM using fibrin glue. In cases with significant shortage of the conjunctiva in the caruncle area, attach either a conjunctival autograft or oral mucosal graft to the caruncle with 8-0 Vicryl and then cover the entire bare sclera with cryopreserved AM as described for primary Pterygium.
Begin topical Prednisolone every 2 waking hours and Ocuflox three times a day for 4 weeks and see the patient at that time (mandatory). If the surrounding conjunctiva is not inflamed (Fig. 8), stop Ocuflox and taper off PF at a weekly schedule from four times a day. If however the surrounding conjunctiva is inflamed (Fig. 9 or 10), give subconjunctival injection of 0.1 cc Kenalog (40 mg/ml) per site in the office at to abort any progression into recurrence and watch for IOP elevation. At time points later than one month, if early recurrence is suspected, you may like to consider subconjunctival injection of 5-FU (5 mg/0.1cc) twice, 2 weeks apart, or holding a sponge soaked with MMC 0.02% at the area of concern for 5 minutes before rinse.
The following studies used cryopreserved amnion graft transplantation for conjunctival surface reconstruction following removal of primary pterygium. For primary pterygium, Prabhasawat et al1 first compared a prospective study using amnion grafts (n=54) to a retrospective study using conjunctival grafts (n=122) in both primary and recurrent pterygium. This study conducted in 1997 noted that the recurrence rate is 10.9% using amnion grafts, which is higher than 2.6% of conjunctival grafts. Nevertheless, both results of amnion grafts and conjunctival grafts are significantly better than the primary closure (n=20), which resulted in 45% high recurrence rate for primary pterygium. Kim et al2 reported a recurrence rate of 18% in 11 primary pterygium (using amnion grafts alone).
In 2001, Solomon et al3 reported that by incorporating a larger removal of subconjunctival fibrous tissue and injection of long-acting steroid (Kenalog), amnion grafts achieved a lower recurrence rate of 3.0%, compatible with 2.6% of conjunctival autografts published by Prabhasawat et al1. Ma et al4 reported 3.7% recurrence rate in 80 eyes using amnion grafts alone, which is compatible with 5.4% of 56 eyes with conjunctival grafts alone, and 3.7% of 54 eyes with topical mitomycin C alone for primary pterygium.
It should be noted that the surgical method proposed here differs from the above in combining both amnion grafts and intraoperative application of MMC (to fornix) and in using fibrin glue (without sutures) measures collectively furthering the success and the ease of care. This new strategy is based on the following literature:
Intraoperative application of mitomycin C (0.04% for 5 min) to the fornix (not the bare sclera) is used as an adjunctive treatment to reduce chronic conjunctival inflammation and augment the efficacy of AMT in restoring a deep fornix after symblepharon lysis5, 6 and together with AMT and conjunctival autograft to restore ocular motility in multi-recurrent pterygia7, 8.
What should I do if I see a separation in the graft edge at nasal fornix in the early post-operative days?
This happens because of poor fibrin glue adhesion or excessive fibrin glue trapped in between. To avoid this, stretch the membrane with the muscle hook toward the cornea to squeeze excess glue out. If the area of graft shows hyperemia or inflammation, give an injection of Kenalog to avoid granuloma formation in one month.
Why would pyogenic granuloma develop and how do you treat it?
Pyogenic granuloma (Fig. 10) may develop for several reasons including exposed sclera or subconjunctival tissue, suture induced trauma, residual fibrovascular tissue, large mass of fibrin glue left, and/or lack of good contact with the MMC soaked sponge during incubation. One can avoid this complication by fully covering the bare sclera with amniotic membrane using fibrin glue without sutures, by making sure there is full contact between the caruncle tissue and the MMC sponge by pushing caruncle down during MMC incubation time via 0.12 forceps, and by carefully monitoring inflammation of the host conjunctival tissue at one month postop visit. If pyogenic granuloma develops, one can increase PF to q2h for one or two weeks. Once the stalk is not congested, it can simply be excised in the office.
What are the advantages of amniotic membrane transplantation over conjunctival limbal autograft in pterygium surgery?
Although the use of free grafts of conjunctiva and limbal tissue is reported to have better success rates, cryopreserved amniotic membrane has the following advantages:
Amniotic membrane can provide consistently better results than conjunctival autograft. However, to achieve this goal, we recommend the use of intraoperative MMC and sealing the gap between the conjunctiva and Tenon’s capsule.
Can we use MMC in patients who have had previous radiation treatment?
It is advisable to avoid using Mitomycin C in such cases as there is increased risk of scleral melting due to pre-existing ischemia.
How far should the pterygium head and body be removed?
If the semilunar fold can be identified, the truncation is made in front of the fold. Excise the subconjunctival fibrovascular tissue/Tenon so that its edge is about 2-3 mm posterior to the conjunctival edge.
How is the corneal epithelial defect handled during pterygium surgery?
For primary pterygium, the cryopreserved amnion graft does not need to go beyond the limbus to cover the corneal defect because corneal healing occurs. For large corneal epithelial defects, a bandage CL can be applied.
After pterygium excision, we have observed that a gap invariably remains between the conjunctiva and Tenon’s capsule, allowing reinvasion (herniation) by the residual fibrovascular tissue and giving rise to recurrence.