Conjunctiva 6

  • View
    1.718

  • Download
    0

Embed Size (px)

Text of Conjunctiva 6

  • 1.Pinguecula
    • Common, innocuous, bilateral, asymptomatic condition
  • Usually seen in elderly people, especially those exposed to strong sunlight, dust & wind.
  • Though yellow in color and looks like fat (hence the name, penguis meaning fat), it is due to hyaline infiltration and elastotic degeneration of the submucous connective tissue.
  • Signs :
  • Yellowish triangular patch of bulbar conjunctiva, near the limbus in the palpebral aperture, the apex of the traingle being away from the cornea.
  • Usually nasal side affected first, then temporal
  • Treatment :usually unnecessary because growth is very slow or absent. If acutely inflammed (pingueculitis) short course of weak steroids (flourometholone)

2. Pinguecula 3. Pterygium

  • A pterygium is a triangular, wing shaped, fibrovascular subepithelial ingrowth of degenerative bulbar conjunctival tissue over the limbus onto the cornea ( pterygos -wing)
  • It is a degenerative condition of subconjunctival tissues which proliferate as a vascularized granulation tissue to invade the cornea, destroying the superficial layers of the stroma and Bowmans membrane, the whole being covered by conjunctival epithelium
  • It is loosely adherent in its whole length to the underlying sclera, the area of adherence being always smaller than its breadth, so that there are folds at the upper and lower borders .

4. 5. Pterygium

  • Etiology :
  • 1. Usually develop in patients who live in hot dry climates, high winds and abundance of dust.
  • 2. Exposure to ultraviolet light (UV type B)in solar radiation is most significant environmental factor.
  • - Involuntary partial closure of the interpalpebral fissure, mostly confined to the temporal side, to avoid glare from bright sunlight, may explain the predominance of pterygia on the nasal side.
  • 3. Genetic predisposition
  • 4. Pinguecula as a precursor of pterygium

6. Pterygium

  • Histopathologically :
  • - it is a fibrovascular proliferation of conj tissue onto cornea
  • - it is hyperplasia, not dysplasia
  • - stains with elastic tissue stains, but unlike elastic tissue, it is not digested by elastase, hence termed elastotic degeneration.
  • - body of pterygium incorporates the underlying Tenons capsule, but not the episclera, hence it can be easily mobilized over the sclera
  • - at the limbus no Tenons hence adherent to episclera
  • - Head of the pterygium grows in a plane between Bowmans layer and the basement membrane of corneal epithelium Bowmans membrane initially pushed posteriorly later gets destroyed and pterygium tissue grows into stroma pterygium becomes firmly adherent.
  • - primary pterygium are histopathologically different from recurrent pterygium : Recurrent pterygium is composed of only fibrovascular tissue, no elastotic degeneration, involves underlying episclera, sclera, rectus muscle sheath and corneal stroma and is firmly adherent to underlying structures throughout its extent, is highly vascularized.

7. Pterygium

  • Clinical Features :
  • A small, grey, corneal opacity develops, near the nasal limbus.
  • The conjunctiva overgrows the opacity and progressively encroaches onto the cornea in a triangular fashion.
  • Anatomically divided into : head, neck and tail.
  • Head part on the cornea
  • Neck at the limbus
  • Tail part on the sclera
  • A deposit of iron (Stocker line) may be seen in the corneal epithelium anterior to the advancing head of the pterygium in slow growing pterygiums, due to pooling of tears at the leading edge of pterygium
  • A probe can be slipped under the upper and lower folded borders of the body of the pterygium for a short extent and not across the entire breadth.

8. Pterygium

  • Classification of pterygium :
  • Progressive Pterygium : actively growing, fleshy, vascular and inflamed looking pterygium with no Stockers line
  • Stationary Pterygium : pterygium still looks vascular, but the head of the pterygium looks pale and sparsely vascularized and stops growing, develops a Stockers line
  • Regressive pterygium : pale, thin, papery, gray, anemic and membranous pterygium appears to be regressing, has a gray apex resembling corneal opacity
  • Nasal
  • Temporal
  • Double pterygia (both nasal and temporal)
  • Bilateral pterygia (both eyes)
  • Primary / Recurrent pterygium (regowth after excision)

9. Pterygium

  • Treatment : surgical treatment is the only effective treatment for pterygium. However, none of the surgical procedures is perfect and universally accepted because of high recurrence rates.
  • Indications for surgery:
  • - primary indication is decreased visual acuity because of encroachment of the pterygium into visual axis or the irregular astigmatism induced by the growth.
  • - restricted ocular motility
  • - binocular diplopia
  • - ocular irritation and discomfortunresponsive to lubrication
  • - where pterygium restricts wearingof contact lenses
  • - difficulty in performing corneal refractive surgery
  • - cosmetic reasons

10. Pterygium 11. Pterygium

  • Current surgical procedures for pterygium treatment
  • Bare Sclera excision
  • Adjunctive use of Beta irradiation
  • Adjunctive use of Thiotepa
  • Adjunctive use of Mitomycin C
  • Conjunctival transplantation / autograft
  • Limbal stem cell transplantation
  • Amniotic membrane allograft transplantation

12. Pterygium

  • Bare sclera excision :
  • - surgical dissection of the pterygium starting from the head of the pterygium with lamellar keratectomy and extending to remove the body of the pterygium. The head, neck and body of pterygium are removed in one piece, leaving behind bare scleral area slightly more than the body of the removed pterygium. Hemostasis achieved using thermal cautery
  • - high rate of recurrence (23 75%)

13. Pterygium

  • Beta irradiation :
  • - Standard Sr-90 applicator (dose : 1500 2500 reps) with shield
  • - expend most of their energy within superficial 2 mm of tissue
  • - irradiation induces obliterative endarteritis and arrest of fibroblast proliferation due to ionization changes in nucleus and cytoplasm of cells
  • - applied immediately after surgical excision of pterygium
  • - reduces recurrence rates to 0.5 16%
  • - limitations : requires trained radiologists / radiotherapists
  • - complications : cataract formation (dose related), dry eyes, corneal/ scleral thinning and ulceration
  • -

14. Pterygium

  • Thiotepa :
  • - rarely used now
  • - nitrogen mustard family
  • - inhibits capillary endothelial proliferation, thereby inhibiting pterygium recurrence
  • - applied as topical drops
  • - poliosis, periorbital skin depigmentation, chronic conjunctivitis, scleral ulceration

15. Pterygium

  • Mitomycin C
  • - antimetabolite agent
  • - selectively inhibits DNA replication, non-cell specific, action during late G1 and S phases of cell division
  • - intraoperative use of 0.02 0.05% (0.2 0.5 mg/dl) Mitomycin C for 30 sec 3 min to bare sclera after pterygium excision
  • - reduces recurrence rate to 4 23 %
  • - postoperative use of mitomycin C topical drops (0.02%)
  • - complications : scleral thinning and perforation, corneal perforation, iritis, secondary glaucoma, cataract

16. Pterygium

  • Conjunctival transplantation (conj autograft):
  • - conjunctival tissue taken from another site of same eye or other eye and grafted to pterygium excision site and sutured using vicryl/ nylon
  • - reduces recurrence rate to 5 7 %
  • - can be combined with intraoperative Mitomycin C application

17. Pterygium

  • Limbal stem cell transplantation (autologous):
  • - healthy limbal epithelium acts as a junctional barrier to conjunctival cells migrating onto corneal surface.
  • - 0.5 mm of limbal/ peripheral corneal tissue is taken along with conjunctival autograft (Limbal conjunctival graft)
  • - graft placed with correct orientation on scleral recipient bed (corneal side towards cornea) and sutured using vicryl/nylon.
  • - recurrence rate 0 15%
  • - limitations : technically demanding, time consuming.

18. 19. Pterygium

  • Amniotic membrane transplantation :
  • - amnion innermost layer of the placenta
  • - amniotic membrane separated from chorion, washed with antibiotics, and cut into small pieces and stored in Eagle medium at 80 oC
  • -stroma of amniotic membrane