lamellar keratoplasty ophthalmology ophthalmology

ppt

1. DALK ( DEEP ANTERIOR LAMELLAR KERATOPLASTY ) Moderator- Dr.John Sarkar Presenter- Dr.Sirisha Rampilla

2. Classification

3. Why lamellar keratoplasty ??

4. ANATOMY LAYERS THICKNESS(µm) COMPOSITION Epithelium 50 Stratified squamous Bowman’s membrane 8-14 Compact layer of unorganized collagen fiber Stroma 500 Orderly arranged collagen lamellae with keratocyte Dua’s layer 10-15 Consists of typ 1 collagen Descemet’s membrane 8-10 Consist of basement membrane Endothelium 5 Single layer of simple squamous epithelium

5. surgical anatomy of stroma Collagen fibrils in Ant. 1/3 Post 2/3 Orientation to corneal surface oblique parallel arrangement Branching present lamella interweave Less loosely placed Thickness of stroma- 478-500 microns The deeper in the stroma the surgeon is, the easier it is to dissect between the lamellae i.e Easier to do LK, The deeper we go

6. ADVANTAGE Non-penetrating surgery Reduced risk of endothelial graft rejection Does not require good endothelial quality donor tissue Technically achieves a stronger corneal wound Suture related astigmatism is lesser DISADVANTAGE Technically more demanding and time consuming Suboptimal visual acuity compared to PK due to Interface problems Lamellar dissection regularity Residual scarring

7. Optical ALK- for visual rehabilitation

8. Tectonic ALK- for re-establishing structural integrity of the cornea

9. Therapeutic – to eliminate corneal infection optical + tectonic ALK MICROBIAL KERATITIS

10. ANTERIOR LAMELLAR KERATOPLASTY Superficial Anterior Lamellar Keratoplasty (SALK) anterior 30 to 50% of cornea stroma-to-stroma interfaces can degrade visual acuity over time Deep Anterior Lamellar Keratoplasty (DALK ) corneal stroma is completely excised up to DM stroma-to-DM interface provides higher quality vision

11. Surgical technique Globe exposure Host cornea marking : optical axis is marked using gentian violet marking pen. Stained 8 or 12 prong radial marker used to aid in suture placement Sizing & trephination : size of opacity measured with measuring caliper Trephine is preset to requisite depth in accordance with depth of stromal involvement Partial thickness trephination of host cornea is done Stromal dissection types: 1.Manual 2. automated

12. 1.MANUAL DISSECTION CLOSED DISSECTION- After desired depth trephination, stromal pocket is made with paufique knife at incision site Introduce lamellar dissector through the pocket while lifting up the anterior lip of the flap Dissection continued by gentle side to side movement and parallel to posterior stroma Smoother preparation but no direct visualisation possible

13. Open dissection Here the edge of the separated anterior lamellar tissue is held retracted with the help of forceps during the dissection enabling direct visualization of the area of separation. 2.AUTOMATED LAMELLAR KERATOPLASTY- Microkeratome used Allows for superior smooth surface Not suitable for thin & irregular corneas as in advanced keratoconus Indications: Stromal lesions limited to anterior stromal layers Moderate keratoconus Post PRK haze

14. In DALK Entire corneal stroma is removed baring the Descemet’s membrane . Adv – elimination of the graft host stromal interface, scarring, irregularity Various methods used to seperate DM from stroma- Air dissection- ANWAR BIG BUBBLE TECHNIQUE most commonly used Viscodissection – Hydrodelamination –saline solution is used

15. Careful manual peeling using tryphan blue for better visualization of DM in donor cornea clevage plane should be between banded and non banded part of DM in recipient preparation Hydrodelamination has 39% chance of perforation Air dissection has 9% chance of perforation

16. ANWAR BIG BUBBLE TECHNIQUE

17. DONOR CORNEA The donor tissue is prepared by punching an appropriate sized CS button with a trephine. Trypan blue can be used to stain the endothelium to improve visualization in order to facilitate the removal to DM and endothelium from donor tissue. Donor tissue is then sutured with host tissue using 10-0 nylon sutures in a contineuos or interrupted fashion.

18. INTRAOP COMPLICATION Descemet membrane perforation- Microperforation –self sealing or inject air to AC Large perforation from rim to rim- suture (10-0 nylon)it with donor stroma. If not possible convert it to PK Pseudoanterior chamber- Due to occult break Due to retained visco Treatment- Shallow double chamber-self limiting, resolve in few week, long standing one required surgical intervention by injecting air to AC Irregular lamellar bed- Causes astigmatism, significant interface haze Can be avoided by big bubble technique or automated microkeratome assisted anterior lamellar keratoplasty

19. Graft-host malapposition /edge irregularity- due to improper sizing of tissue Adopt hemi-automated anterior lamellar procedure in which the trephine is used to cut grafts of appropriate size after the donor automated cuts on the donor cornea and the host corneal lamellar dissection is performed manually. Interface debris- due to fibers , bleeding Wash thoroughly after procedure

20. POST OP COMPLICATION Persistent epithelial defect Infection : Graft infection due to various causes such as suture related, lid adnexal abnormalities, poor ocular surface, prolonged topical steroid, poor hygiene Recurrence of the primary pathology- ex HSV, corneal dystrophy Graft Rejection- less common Graft vascularization -can be seen in ocular surface pathologies such as trachomatous keratopathy, chemical burns and Stevens-Johnson syndrome.

21. RECENT ADVANCES FEMTOSECOND LASER DSAEK • This laser is used to create flaps in LASIK and can be used to perform keratoplasty with different shapes of stromal cut. The laser uses an infrared wavelength (1053nm) to deliver closely spaced, 3 microns spots that can be focused to a preset depth to photodisrupt the tissue within the corneal stroma. Femtosecond laser is used to create a dissection plane on the donor cornea mounted on artificial anterior chamber. Offers a potential advantage over microkeratome with regards to better sizing of the posterior lenticule. Obtains a smooth surface and precise stromal cuts

22. Sutureless corneal adhesion Bioadhesive (Fibrin glue)- Kaufman et al successfully used fibrin glue in small series of lamellar keratoplasty Photochemical keratodesmos is method of producing sutureless adhesion by applying a photosensitizer to wound surfaces followed by low energy laser irradiation. Laser promotes cross linkage between collagen molecules to produce tight seal without thermal damage

23. Thank you