recent developments in corneal surgery

Dr Laurie Sullivan FRANZCOCorneal Clinic, RVEEH

Bayside Eye Specialists, Brighton 100 Victoria Parade, East Melbourne

Lasersight

Background of Corneal Transplantation

The first cornea transplant was performed in 1905, by Eduard Zirm – sutures over the graft

– 1 of 2 eyes survived!Operating microscopes have enabled us to get a

better view of the surgical fieldAdvances in materials enabled us to use nylon

sutures finer than a human hairThe development of synthetic corticosteroids

has enabled inhibition of rejection In Australia, approximately 1,500 grafts are

performed each year (20% are for keratoconus)

Dr Laurie Sullivan 2008 www.baysideeyes.com.au

Why was Lamellar Corneal Transplantation out of favour for decades?

Because the eyes did not see well after surgery.Interface irregularities between the two stromal

surfaces produce light scatter causing poor acuity.Full thickness transplants were much better optically

(although the problems of regular and irregular astigmatism still remained).


Previous model of lamellar keratoplasty


Why has lamellar grafting made such a huge comeback?

Because they see better than they did previously

A lamellar graft is structurally stronger than a PK.

Rejection is less


Evidence?


Trans Am Ophthalmol Soc. 2007 December; 105: 530–563.


ENDOTHELIAL KERATOPLASTY: CLINICAL OUTCOMES IN THE TWO YEARS FOLLOWING DEEP LAMELLAR ENDOTHELIAL KERATOPLASTY. (AN AMERICAN OPHTHALMOLOGICAL

SOCIETY THESIS) Mark A. Terry, MD Trans Am Ophthalmol Soc. 2007 December; 105

Purpose: To evaluate the clinical outcomes of deep lamellar endothelial keratoplasty (DLEK) for the treatment of endothelial dysfunction.Methods: A prospective series of 79 eyes that underwent DLEK was evaluated. BSCVA, astigmatism, and central endothelial cell density (ECD) were measured preoperatively and at 6, 12, and 24 months.Results: Data was available on 78 eyes (99%) at 6 months, 77 eyes (97%) at 1 year, and 79 eyes (100%) at 2 years. Mean BSCVA preoperatively of 20/71 improved to 20/42 by 6 months and remained stable. BSCVA of 20/40 or better was present in 60% of eyes at 6 months, 74% of eyes at 1 year, and 79% of eyes at 2 years. Astigmatism preoperatively was .91 ±.78 diopters and was unchanged by surgery over time .The mean donor ECD preoperatively was 2819 ± 225 cells/mm2, and this decreased by 26% at 6 months (2095 ± 380), 3% fewer at 1 year (2009 ± 393), and 17% fewer at 2 years (1536 ± 547). Complications included one primary graft failure and 4 graft dislocations.

ConclusionsDLEK provides improved vision and minimal refractive astigmatic change, but progressive ECD decrease over time is of concern.


Am J Ophthalmol. 2007 Feb;143(2):228-235.

Quality of vision and graft thickness in deep anterior lamellar and penetrating corneal allografts.

Ardjomand N, Hau S, McAlister JC, Bunce C, Galaretta D, Tuft SJ, Larkin DF.

Cornea and External Diseases Service, Moorfields Eye Hospital

PURPOSE: To compare visual function after deep anterior lamellar keratoplasty (DALK) with visual function after penetrating keratoplasty (PK) for keratoconus. DESIGN: Retrospective case series. METHODS: 32 eyes with DALK or PK for keratoconus were analyzed for visual quality after suture removal. Total and residual stromal thickness after DALK was measured using OCT and correlated to visual quality. RESULTS: Eyes after PK had better visual acuity than eyes after DALK (P = .018). Subgroup analysis revealed that DALK Eyes with a recipient corneal bed thickness of <20 microm had visual acuities similar to eyes with a PK, whereas those with a recipient thickness of >80 microm had a significantly reduced visual acuity (P = .0009). Contrast sensitivity was similar in DALK and PK eyes. There was no significant difference in HOAs between eyes with DALK or PK. CONCLUSIONS: These data suggest that the main parameter for good visual function after DALK for keratoconus is the thickness of residual recipient stromal bed. An eye with a DALK with a residual bed of <20 microm can achieve a similar visual result as a PK.

http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=Search&Term=%22Ardjomand%20N%22%5BAuthor%5D&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVAbstract

http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=Search&Term=%22Ardjomand%20N%22%5BAuthor%5D&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVAbstract

http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=Search&Term=%22Hau%20S%22%5BAuthor%5D&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVAbstract

http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=Search&Term=%22Hau%20S%22%5BAuthor%5D&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVAbstract

“Endothelial Keratoplasty” (DSAEK, DMEK)

Why remove the full thickness of the cornea if you only need to replace the endothelium?


Indications

Endothelial diseaseFuch’s dystrophy, PPD Pseudophakic bullous keratopathy (PBK)Other endothelial failure (AACG, PXF)

The eye should be pseudophakic (AC manipulation during surgery would cause cataract). Surgery can be combined with cataract and IOL.


DSAEK


DSAEK

Remove host Descemet’s membraneReplace with lenticle of donor Descemet’s

membrane and posterior stroma (100 to 150 µm) prepared using a microkeratome to dissect anterior stroma

Air bubble to hold in placeNo corneal sutures, minimal astigmatism


Postop DSAEK vs PK


DSAEKMain benefit is relatively rapid rehabilitation

1 to 2 months compared to 3 to 12 months for PK

Better structural integrity than PKNo sutures, less astigmatism, fewer visitsThe issue of the interface remains, with lower

BCVA the PK → DMEK??Ideal patient a little old lady from the country


DSAEK POD1Bubble behind pupil Dilated, postured


DSAEKMain disadvantages: Lower BCVA than PKShorter survival of transplanted tissue (endothelial

trauma during insertion)?1-10% postoperative interventions for detached and

displaced donor lenticles, pupil blockAll improving with new techniques and instruments,

larger incisions, rolling of donor lenticles“Endothelial transplantation” (ET, DMEK)

Transfer endothelium and Descemet’s membrane only – NO stroma – less interface opacity


DSAEK Dislocation Day 2 postop


Femtosecond Laser for Penetrating Keratoplasty

Intralase was introduced initially to produce LASIK flaps

Intralase can produce complex, complementary donor and host wound profiles

“Intralase Enabled Keratoplasty” = IEK


Top Hat Shape

•


Top Hat Shape

• Provides large endothelial surface transplantation• Uniform anterior refractive surface• Also true for other shapesDr Laurie Sullivan 2008 www.baysideeyes.com.au

Valve-Sealing Edge Design

SutureNot Tight

Intraocular Pressure

Prevents Leakage


ZigZag Shape

• Hermetic wound seal

• Angled edge provides smooth transition between host and donor


Anterior Lamellar Keratoplasty

DALK = Deep ALK“Stroma-only” keratoplastyRemove all host corneal stroma, leaving only

endothelium and Descemet’s membrane Less host stroma means less interface hazeCannot be rejected2 main techniques

Melles’ direct dissection (difficult)Anwar’s Big Bubble (easier)


DALK IndicationsEyes with healthy endotheliumKeratoconus, anterior scars, dystrophiesSevere atopyEyes at high risk for endothelial rejection inc

large diameter grafts (Pellucid, Keratoglobus)Unreliable patients, trauma risk (young males)Down’s syndromeNow my preferred option for KCN


DALK results

Slightly longer, more difficult surgery (learning)VA equivalent to PK if stroma < 20 micronsNo better for astigmatism resultsSlightly earlier suture removalCan still have wound and suture problems,

infectionMay need to reinject air bubble into AC in the 1st

week


DALK Postop Day 1 & 2


Suture related keratitis – no rejection


Keratoconus and Corneal Collagen Crosslinking

Q. Why does keratoconus stabilise?

Q. Why do corneas become “stiffer” with age?

A. Increased collagen crosslinking - ?related to lifelong UV exposure.


“Corneal Collagen Crosslinking With Riboflavin” = C3R = CXL

Keratoconic corneas show less crosslinking of collagen fibrils than normals

This may cause decreased resistance to stretchTreatment with UVA light can promote collagen

crosslinking (as seen in the ageing cornea)

Riboflavin is a very good photosensitiser to UVA


C3R/CXL - the treatment

Like PRK 8mm epithelial debridement (similar to PRK)

Sore eyeBlurry(er) vision for a weekRisk of infection2- 4 weeks out of RGP CL

Stroma is soaked with riboflavin drops every 5 minutes

30 minutes of UVA light exposure (3.5 Mw/mm2) under an operating microscope

Padded (or bandage SCL), ointment, antibiotics, steroids, lubricants


ICOR UVA diode system


Results of C3R Treatment

Slows or stops progression of KCNSome reversal (flattening) in 25%Maybe better spectacle corrected vision

Consequences:? Longer duration of tolerability, fittability of rigid

contact lenses? ? Fewer transplants?


C3R long term

Duration of effect? – may need repeat treatment at 5 or 10 years – not so far (6years follow up for the initial Dresden cohort)

??Long term adverse effects (later OSSN / CIN, endothelial failure?)


Intracorneal ring segments (ICRS)IntacsFerrara rings

Originally designed to treat low myopia, but less accurate than excimer laser

Now having a second life in milder KCN


Intacs


ICRS: how they workThe ring segments

flatten the cornea similarly to the way you can flatten the top of a tent by pushing on the sides.


Intacs for KCN – who can benefit?Mild to moderate keratoconusDecreased SCVAA single segment inserted below the cone may

give better results than 2 segments?May be combined with C3R to “set” the cornea

in the new shape


Keratoconus management - Then

Glasses → RGP contact lenses → Corneal Transplant (penetrating)

Then: glasses 70%, RGP 20%, nothing 5 -10%LASIK/PRK, 12 months after suture removal – if

BSCVA is reasonable. Not good for irregular astigmatism.


Keratoconus management - Now

Consider C3R/CXL at diagnosis or if progressingIntacs segments may keep patients in glasses

longer (but results are not dazzling in my experience)

DALK is becoming a more popular corneal transplant option (“Big Bubble” technique)

Gls, RGP, laser as before


Summary

The field of corneal transplantation is evolving rapidlyTechniques and technology seem to be leading the wayStand by for updates even in the next few monthsDALK Video 2:29 If time permits

DALK Video 2:29

If time permits


recent developments in corneal surgery

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