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?