OPT 329 Corneal Transplants

recalcitrant corneal edema due to...

Fuchs’ endothelial dystrophy

Pseudophakic Bullous Keratopathy (PBK)

Aphakic Bullous Keratopathy (ABK)

Iridocorneal Endothelial (ICE) Syndromes

congenital corneal disorders/dystrophies

What indication for corneal transplant is seen here?

dense stromal corneal opacification due to...

acquired scarring (trauma, chemical injury, burn, SJS, OCP, trachoma, HSV, ulcers)

stromal dystrophies (granular, lattice, macular)

What indication for corneal transplant is seen here?

decreased vision from irregular astigmatism such as...

KCN

post-LASIK ectasia

post-RK

What indication for corneal transplant is seen here?

chronic eye pain from corneal disease

What indication for corneal transplant is seen here?

pupils - APD?

Maddox rod orientation

dilated PH acuity similar to CAT Sx

B scan to assess retina, vitreous, ONH

electrodiagnostics ERG, VEP

How can we determine expected visual outcome during pre-op evaluation?

confirm pain is due to corneal pathology

What do we want to consider with pain during pre-op evaluation?

abnormalities need to be treated surgically first = trichiasis, entropion, ectropion, lagophthalmos, symblepharon

What do we want to consider with eyelid health during pre-op evaluation?

significant neo, cicatrization, loss of limbal stem cells will increase risk of graft rejection = may benefit from keratoprosthetics device

What do we want to consider with ocular surface health during pre-op evaluation?

HSV Hx = start antivirals

inflam disease or graft failure Hx = start oral prednisone

corneal neo = start topical steroid

What do we want to consider with prophylactic medications during pre-op evaluation?

is pt able to comply with maintaining head position, using medications, follow-up visits for life

What do we want to consider with post-op compliance during pre-op evaluation?

full thickness keratoplasty of all layers with "open sky" = eye is completely open while circular button is removed

What is a penetrating keratoplasty (PKP)?

monitored anesthesia care with sedation, topical anesthetics, retro or peribulbar block - rarely general anesthesia

What type of anesthesia is used for PKP?

corneal trephine = basically like a donut hole maker

corneal scissors finish off

What is mostly commonly used to make the full thickness cut in PKP?

femtosecond laser

What is alternatively used to make the full thickness cut in PKP?

7.75 to 8.50mm diameter = graft is typically 0.25-0.50mm larger than recipient's opening

How large are the grafts typically in PKP?

promote more astigmatism bc sutures closer to visual axis

What is the downside of smaller grafts used in PKP?

higher risk for rejection bc closer to limbal vessels

What is the downside of larger grafts used in PKP?

quicker

less astigmatism early in healing

What are the 2 pros of a continuous suture used in PKP?

suture can break or abscess = difficult to fix bc need to replace entire line = not common anymore today

What is the con of a continuous suture used in PKP?

best for corneal neo

good for peds, mentally impaired, obese pt's bc easier to fix any ruptures from eye rubbing, etc.

What are the 2 pros of 16-30 interrupted sutures used in PKP?

induces more astigmatism initially

What is the con of 16-30 interrupted sutures used in PKP?

VA typically poor

assess graft for edema, abrasions/defects

sutures should have junctional integrity (-)Seidel

AC depth and rxn

IOP with iCare or NCT = NO Goldmann for several weeks

What exam components should be performed at the 1 day post-op for a PKP?

high IOP if retained viscoelastic

low IOP if hypotony/wound leak

Why might we see high vs low IOP post-op with PKP?

abx broad spectrum x 2 weeks

steroid QID like Pred forte, Durezol x 1 month, then slow monthly taper to qday for life

topical and/or oral immunosuppressive

What are the 3 post-op medications dictated by the surgeon for PKP?

NO rubbing

NO bending or Valsalva movements

shield while sleeping x2 weeks

eye protection at all times

NO water in eye

clean environments (avoid dust, dirt, smoke)

What some important post-op pt limitations we need to educate on?

VA still may be poor

ASeg - assess graft, sutures, AC

IOP with iCare or NCT

fundoscopy may be difficult

What exam components should be performed at the 1 week post-op for a PKP?

S/S of graft rejection and to RTC asap to avoid graft failure = pain, decreased vision, redness, photophobia

In addition to the post-op limitations, what is 1 other thing we should educate our pt on at the 1 week post-op for a PKP?

VA

refraction and topography

ASeg - assess graft, sutures, AC - esp concerned with edema, surface integrity

IOP with iCare or NCT

fundoscopy

What exam components should be performed at the 1 month post-op for a PKP?

1 month post-op

When can a pt begin activity and light exercise after PKP?

3 months

For how long should we monitor astigmatism before making adjustments after PKP?

donor/host tissue

underlying disorder = KCN, PMD

placement of trephination

graft size

donor and host corneal thickness disparity

suturing technique

post-op wound healing, inflammation, medications, vascularization

What can affect the astigmatism changes after PKP?

5D or more

15-31% of post-PK patients will develop at least how much astigmatism?

use refraction and topography to determine steep axis = remove 1-2 sutures at a time along the steep axis = relaxes/flattens that axis

How can we manage/tweak astigmatism after PKP with interrupted sutures (more common)?

use refraction and topography to determine steep axis = loosen suture tension along the steep axis = relaxes/flattens that axis

NOTE: be careful not to cut or else entire suture must be removed

How can we manage/tweak astigmatism after PKP with continuous sutures (less common)?

opposite

When we remove sutures after PKP, the pt needs to look in the ________________ direction of the suture being removed.

proparacaine OU +/- povidine-iodine 5%

26 gauge needle or beaver blade inserted under suture, bevel up

cut suture away from knot with a bold, steady motion

forceps to grab long end of suture and tug gently

instill and Rx abx

Explain the process for removing sutures after a PKP.

limit how far the knot travels in the cornea

AND

limit how much of the exposed suture enters cornea

When removing a suture after PKP, we want to limit which 2 things?

relaxing incision in the steep meridian if < 6D

relaxing incision with compression suture(s) in the flat meridian if > 6D

toric ICL

RLE with toric IOL

femtosecond incisions

PRK with mitomycin-C (better than LASIK)

wedge resection = remove tissue from certain quadrants

regraft

If adjusting sutures does not adequately adjust astigmatism after PKP, what other techniques can we use?

80-90%

According to Lam and Reza (2009), PKP is the most successful solid tissue transplant procedure with a success rate of up to ______%.

KCN

Fuch's

central scar

granular dystrophy

According to Lam and Reza (2009), which 4 pre-op conditions have an excellent prognosis >90% for PKP?

advanced Fuch's

PBK or aphakic BK

latent HSK

macular dystrophy

According to Lam and Reza (2009), which 4 pre-op conditions have an good prognosis 80-90% for PKP?

active bacterial keratitis

active HSK

active fungal infection

lattice dystrophy

mild chemical injury

According to Lam and Reza (2009), which 5 pre-op conditions have an fair prognosis 50-80% for PKP?

severe chemical injury

OCP

SJS

multiple graft failures

According to Lam and Reza (2009), which 4 pre-op conditions have an poor prognosis 0-50% for PKP?

immunologic response of host to the donor tissue = graft is clear for 2 weeks after surgery, then becomes edematous with KP's on graft only, neo, infiltrates, Khadadoust endo rejection line, epi rejection line, SEIs

What is graft rejection, a complication of PKP?

stromal infiltrates

What sign of graft rejection, a complication of PKP, is seen here?

Koudadoust endothelial rejection line = line of WBC on endo that will migrate = literally separates immunologically damaged endo from healthy

What sign of graft rejection, a complication of PKP, is seen here?

epithelial rejection line = destruction of donor epithelium, defect is covered by host epithelium

What sign of graft rejection, a complication of PKP, is seen here?

pre-op or Hx of inflam

corneal neo

young host

iris synechiae to the margin of the graft

large graft

prior ocular surgery

loose sutures

prior graft rejection

prior use of glaucoma meds

What are some risk factors for graft rejection in PKP?

topical steroids or ung, sub-tenon's if necessary

epi and subepi rejection = Pred forte or Durezol q1hr = easily reversed

endo rejection = topical q1hr and oral = more difficult

What is the mainstay tx for graft rejection, a complication of PKP?

CATs

glaucoma

impaired healing

immunosuppression = risk of infectious keratitis (bacterial, viral, fungal)

crystalline keratopathy

While topical steroids are the mainstay tx for graft rejection in PKP, what are some S/E of their chronic use?

gray-white branching stromal opacities due to Viridans streptococci biofilm

What is crystalline keratopathy that occurs from chronic topical steroid use?

calcineurin inhibitors = Immunosuppressants that inhibiting the enzyme that activates T-cells of the immune system (e.g. 1-2% cyclosporine gtts, oral tacrolimus)

anti-VEGF pretreatment in high immune risk and corneal neovascularization patients (e.g. Avastin (bevacizumab)

While topical steroids are the mainstay tx for graft rejection in PKP, what are 2 other options for tx?

non-immune mediated failure of donor tissue/graft itself (improper storage, surgical trauma, etc) = corneal edema immediate post-op that never clears

What is graft failure, a complication of PKP?

replaces diseased stroma while preserving Descemet's and endo = good for advanced keratoconus, dense stromal scarring, stromal dystrophies

What is a deep anterior lamellar keratoplasty (DALK) and what conditions is it indicated for?

“Big Bubble” technique = injection of air

How does the surgeon dissect the host stroma and Descemet's membrane in DALK?

lower risk of endophthalmitis

lower risk of expulsive hemorrhage

no risk of endothelial rejection

increased wound integrity

What are some advantages of DALK?

very challenging to learn and master

time consuming

high rate of Descemet’s rupture = convert to PK

What are some disadvantages of DALK?

newer surgery = implant of a mid-stromal Bowman's layer graft = flattens and strengthens an abnormally steep cornea

What is a Bowman's layer transplantation (BLT)?

inlay = graft into mid-stroma for tx of advanced KCN

onlay = tx of persisent sub-epi haze after PRK (almost like a permanent amniotic membrane for a diseased cornea)

What is the difference between an inlay vs onlay graft in a Bowman's layer transplantation (BLT)?

donor corneoscleral button mounted onto artificial AC

epi and BM debrided with sponge, spatula

stroma inflated with air (opaque now) to visualize Bowman's

Tryptan blue stains Bowman's to visualize

Bowman's is scored with a 360deg with 30g needle, then peeled off

Explain the general process of retrieving donor Bowman's in a BLT.

corneoscleral tunnel created

AC filled with air through paracentesis

mid-stromal pocket created limbus-to-limbus

graft inserted into pocket on a surgical glide

AC reformed

wound closed w/ 1 suture = good structure maintained

Explain the general process of inserting Bowman's into host in a BLT.

up to 8 D

BLT can reduce astigmatism in a KCN pt by how much?

minimally invasive

NO surface incisions are made

NO sutures to fixate the graft

Bowman’s layer is acellular, graft rejection unlikely

What are some advantages of BLT?

Bowman's perforation (10%) but easily aborted and allowed to heal

What is the main complication of BLT?

posterior lamellar transplant for endothelial disease, such as Fuch's, Pseudophakic Bullous Keratopathy (PBK) or Pseudophakic Corneal Edema (PCE), Iridocorneal Endothelial Syndromes (ICE)

What is a Descemet's stripping automated endothelial keratoplasty (DSAEK) and when is it used?

Descemet's is stripped from the stroma with microkeratome

posterior lamellar graft of post stroma, Descemet's, endo is inserted

AC air bubble helps adherence

Explain the process of DSAEK.

graft tissue is thicker than tissue removed

creation of a new optical interface in the cornea

induces astigmatism, scatter and aberrations

What are the 3 main optical drawbacks of DSAEK?

transplantation of only Descemet's and endo

What is a Descemet's membrane endothelial keratoplasty (DMEK)?

improved visual outcome

less astigmatism compared to PK or DSAEK

reduced rejection rates

What are the advantages of Descemet's membrane endothelial keratoplasty (DMEK)?

more difficult graft preparation bc easy to tear

more difficult surgical technique bc tendency to "scroll"

increased graft dislocation rates if pt sits up, rubs eye

pt must remain supine for 48hrs until bubble dissolves

What are the disadvantages of Descemet's membrane endothelial keratoplasty (DMEK)?

center of graft is only Descemet’s membrane and endothelium while the periphery of graft has a small portion of stromal tissue

What is a Descemet's membrane automated endothelial keratoplasty (DMAEK)?

good optics along visual axis, while reducing the difficulty of the surgery and dislocation of the graft

Why was the DMAEK created from a hybrid of DSAEK and DMEK?

artificial corneal transplant = surgeries of last resort!

What is prosthokeratoplasty (Kpro)?

may restore vision to otherwise blind individual = life-changing

What are some advantages of prosthokeratoplasty (Kpro)?

very complicated with high rate of complications (endopthalmitis, glaucoma, RD)

greatly decreased VF

multiple surgeries over months to years

life-long follow-up

cosmetically unattractive

What are some disadvantages of prosthokeratoplasty (Kpro)?

true

True or False: the Boston K-Pro uses a donor corneal graft between the front optical stem and the back plate.

optics of visual axis maintained even if the graft fails and becomes opaque

can be implanted in children 1-year and older to prevent amblyopia

What are some advantages of the Boston K-Pro?

unable to check IOP

fortified antibiotic drops must be applied daily to prevent infection

50% complication rate at 5-years

What are some disadvantages of the Boston K-Pro?

one-piece, non-rigid synthetic corneal implant = implanted into stromal pocket and covered with graft/amniotic membrane for 2 mos, then overlying conj and cornea are removed via trephination

What is the AlphaCor Kpro?

uses a single root tooth, some jaw bone, and buccal mucosa to create a new ocular surface and foundation for a PMMA optical cylinder

What is the Osteo-Odonto-Keratoprosthesis (OOKP)?