1. Update on Pterygium Therapy
Jay C. Bradley, MD
David L. McCartney, MD
January Grand Rounds

2. From the BCSC: Basics Often bilateral
Almost always situated at the nasal or temporal limbus within palpebral fissure
Associated with prolonged UV exposure
UV-B  limbal stem cell p53 mutation   apoptosis /  TGF-   growth
May be associated with dryness, inflammation, and exposure to wind and dust or other irritants
Prevalence increases with proximity to equator
Difficult to determine if race is independent risk factor due to confounding variables

3. Albedo Hypothesis Researcher: MT Coroneo (Australia)
Pterygia occur secondary to albedo concentration in the anterior eye
Light entering the temporal limbus at 90 degrees is concentrated onto the medial limbus
Related to corneal curvature
Explains predominance of medial pterygia
Ophthalmic surg Jan;21(1):60-6.

4. From BCSC: Basics Encroaches on cornea in wing-like fashion
Overlying epithelium often thinned, but can be hyperplastic or dysplastic
Nearly always preceded by pingueculae
Induces astigmatism (usually “with-the-rule”) proportional to size
Excision indicated if persistent irritation, vision distortion, significant (> 3-4 mm) and progressive growth toward visual axis, restricted ocular motility, and atypical appearance

5. From the BCSC: Basics
Elastotic degeneration – fragmentation and breakdown of stromal collagen
Destruction of Bowman’s layer by advancing fibrovascular tissue resulting in corneal scarring

6. From BCSC: Basics
Recurrent pterygia – lack elastotic degeneration and are more accurately classified as an exuberant granulation tissue response
Stocker’s line – a pigmented iron line in advance of pterygium

7. Pterygium Excision
Goal: Achieve a normal, topographically smooth ocular surface
Dissect a smooth plane toward the limbus
Some surgeons prefer specialized blunt pterygium blades (Tooke or Gills) while others prefer sharp blades
Preferable to dissect down to bare sclera at limbus
Bare sclera = remove loose Tenon’s layer and leave episcleral vessels intact

8. Some surgeons avoid medial dissection to avoid bleeding from trauma to adjacent muscle tissue while other remove excessive fibrovascular tissue medially
Light thermal cautery is applied for hemostasis

9. Pterygium Recurrence
Growth of fibrovascular tissue across the limbus onto cornea after initial removal
Excludes persistence of deeper corneal vessels and scarring which may remain even after adequate removal
Bunching of conjunctiva and formation of parallel loops of vessels, which aim almost like an arrowhead at the limbus, usually denotes a conjunctival recurrence

10. Proposed Recurrence Grading System
Grade 1 – normal appearing operative site
Grade 2 – fine episcleral vessels in the site extending to the limbus
Grade 3 – additional fibrous tissues in site
Grade 4 – actual corneal recurrence

11. Wound Closure Options:
Bare sclera
Simple closure
Sliding flap
Rotational flap
Conjunctival graft

12. Bare Sclera Closure
No sutures or fine, absorbable sutures used to appose conjunctiva to superficial sclera in front of rectus tendon insertion
Leaves area of “bare sclera”
Relatively high recurrence rate with variable techniques of 5 – 68 % with primary / 35 – 82 % with recurrent)

13. Simple Closure Free edges of conjunctiva secured together
Effective only if defect is very small
Can be used for pingueculae removal
Reported recurrence rates from 45 – 69 % (one report of “barest” sclera, N=800 of 2 %)
Few complications (dellen)

14. Sliding Flap Closure
An L-shaped incision is made adjacent to the wound to allow conjunctival flap to slide into place
Reported recurrence rates from 0.75 – 5.6 % (poorly designed, retrospective)
Few complications (flap retraction / cyst formation)

15. Rotational Flap Closure
A U-shaped incision is made adjacent to the wound to form tongue of conjunctiva that is rotated into place
Reported recurrence of 4 %
Few complications

16. Conjunctival Graft Closure
A free graft, usually from superior bulbar conjunctiva, is excised to correspond to wound and is then moved and sutured into place
Can be performed with inferior conjunctiva to preserve superior conjunctiva

17. Conjunctival Graft Closure
Harvested tissue should be approximately 0.5 – 1 mm larger than defect
Most important aspect in harvesting is to procure conjunctival tissue with only minimal or no Tenon’s included
Graft is transferred to recipient bed and secured with or without incorporating episclera
Some surgeons harvest limbal stem cells along with graft and orient graft to place stem cells adjacent to site of corneal lesion excision

18. Conjunctival Graft Closure
Topical antibiotic-corticosteroid ointment used for 4 – 6 weeks post-operatively until inflammation subsides (compliance with this regimen decreases recurrence)
Used when extensive damage or destruction of limbal epithelial stem cells is NOT present
Reduces recurrence to 2 – 5 % (up to 40 % in some reports)
Ameliorates the restriction of extraocular muscle function

19. Limbal Conjunctival Autograft
Reported recurrence rates are variable (between 0 – 40 %)
Few complications
Further prospective studies in primary and recurrent pterygia are needed

20. Lamellar Corneal Transplant
Wound closed with piece of lamellar sclera or cornea
Reported recurrence rates of 6 – 30 %
Not performed often
Can be used in conjunction with AMT for multiply recurrent pterygia with corneal scarring and limited available conjunctiva
Method involves increased surgical complexity, the requirement of donor tissue, and risk of infectious disease transmission

21. Adjunctive Beta Irradiation
Most common dosage is 15 Gy in single or divided doses
Reasonably acceptable recurrence rates (from 0 – 50 % with bare sclera or simple conj closure)
Risk of corneal or scleral necrosis and endophthalmitis

22. Adjunctive Thiotepa
Most common dose is 1:2000 thiotepa given up to every 3 hours for approx. 6 weeks
Usually used with bare sclera method
Low reported recurrence rates of 0 – 16 % (poor study quality)
Minimal complications (2 cases of scleral thinning)

23. Adjunctive Mitomycin C
Used with bare sclera or conj closure
Most common dose is 0.02 % applied for 3 min during surgery
Risk of aseptic scleral necrosis / perforation and infectious sclerokeratitis
Used more often for recurrent cases
Rate of recurrence between 3 – 25 % for intra-op / 5 – 54 % for post-op with most studies showing < 10 % recurrence

24. Amniotic Membrane Graft Closure
Useful for very large conjunctival defects as in primary double-headed pterygium or to preserve superior conjunctiva for future glaucoma surgeries
Requires costly donor tissue
Reported recurrence rate between 3 – 64 % for primary cases and 0 – 37.5 % for recurrent cases

25. Other Methods:
Pterygium head transplantation
Split skin grafts
Ruthenium adjunctive therapy
Laser or thermal cautery
Excimer laser treatment
PDT (one report, N = 10)
Intraoperative doxorubicin / daunorubicin
5-FU
Serum-free derived cultivated conjunctival graft
Recombinant epidermal growth factor
****Few studies with limited numbers of patients, poor follow-up, and variable recurrence rates

26. Primary Pterygium Metanalysis
Includes 5 studies with N=290 (BS+Mito=257/CAG=33)
Comparison Odds Ratio % CI
Bare sclera: mito C : – 66.7
Bare sclera: CAG : – 18.8
Sanchez-Thorin JC et al. Br J Ophthalmol 82:661-5, 1998.

27. Conclusions: There is no clear-cut superior single treatment
Bare scleral and simple conjunctival closure without adjunctive therapy have relatively high but variable recurrence rates
Use of beta irradiation and antimetabolites can be used with appropriate caution
Conjunctival transplants and flaps appear to have overall lower rate of recurrence but require more surgical time and unnecessary conj destruction
Other treatment options need further adequate study prior to widespread implementation

28. Any Questions?