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Update on Pterygium TherapyUpdate on Pterygium Therapy
Jay C. Bradley, MD
David L. McCartney, MD
January Grand Rounds
From the BCSC: BasicsFrom 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
Albedo HypothesisAlbedo 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. 1990 Jan;21(1):60-6.
From BCSC: BasicsFrom 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
From the BCSC: BasicsFrom the BCSC: Basics Elastotic degeneration – fragmentation and
breakdown of stromal collagen
Destruction of Bowman’s layer by advancing fibrovascular tissue resulting in corneal scarring
From BCSC: BasicsFrom 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
Pterygium ExcisionPterygium 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
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
Pterygium RecurrencePterygium 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
Proposed Recurrence Grading Proposed Recurrence Grading SystemSystem
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
Wound Closure Options:Wound Closure Options:
Bare scleraSimple closureSliding flapRotational flapConjunctival graft
Bare Sclera ClosureBare 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)
Simple ClosureSimple 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)
Sliding Flap ClosureSliding 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)
Rotational Flap ClosureRotational 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
Conjunctival Graft ClosureConjunctival 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
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
Conjunctival Graft ClosureConjunctival Graft Closure
Conjunctival Graft ClosureConjunctival 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
Limbal Conjunctival AutograftLimbal Conjunctival Autograft
Reported recurrence rates are variable (between 0 – 40 %)
Few complications Further prospective studies in primary and
recurrent pterygia are needed
Lamellar Corneal TransplantLamellar 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
Adjunctive Beta IrradiationAdjunctive 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
Adjunctive ThiotepaAdjunctive Thiotepa
Most common dose is 1:2000 thiotepa given up to every 3 hours for approx. 6 weeks
Usually used with bare sclera methodLow reported recurrence rates of 0 – 16 %
(poor study quality)Minimal complications (2 cases of scleral
thinning)
Adjunctive Mitomycin CAdjunctive 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
Amniotic Membrane Graft Amniotic Membrane Graft ClosureClosure
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
Other Methods: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
Primary Pterygium Primary Pterygium MetanalysisMetanalysis
Includes 5 studies with N=290 (BS+Mito=257/CAG=33)
Comparison Odds Ratio 95 % CI
Bare sclera: mito C 25:1 9.0 – 66.7
Bare sclera: CAG 6:1 1.8 – 18.8
Sanchez-Thorin JC et al. Br J Ophthalmol 82:661-5, 1998.
Conclusions: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
Any Questions?