09.0013 keratoconus leaflet v2 - accuvision laser eye clinics keratoconus leaflet.pdf · what is...

L A S E R E Y E C L I N I C S

KERATOCONUS

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• Diagnosis• Treatment options• Aftercare

Your complete treatment solution

focusonACCUVISION

09.0013 Keratoconus leaflet v2 3/7/09 12:11 pm

WHAT IS KERATOCONUS?�

Keratoconus is a congenital disease ofthe cornea (autosomal dominant orautosomal recessive) and it belongs tothe large group of hereditary cornealdystrophies.

The disease is characterised by thinningand conus-like protrusion of the cornea.This is due to alterations that causeweakening of the corneal structure.

At first, the protrusion occurs in the inferiorparts (lower half) but later on it also affectsthe central part of the cornea. Keratoconusmostly happens to be bilateral but oftenthe progression is asymmetrical.

Symptoms of KeratoconusKeratoconus symptoms usually start duringpuberty or early adolescence. As thekeratoconus progresses it leads to myopia(short sight) and, if the steepening of thecornea is uneven, also astigmatism(distortion of vision). In most cases patientsrealise a decrease or blurring in vision, or anincreasing myopia with a significantprogression of astigmatism. Patients usuallyseek corrective lenses at first for driving orreading. Keratoconus at this stage isdifficult to differentiate from other morecommon vision defects. The incidence ofkeratoconus in the general population isreported to be about 1 in 2000.

Keratoconus is commonly associated withother health disorders. Eye conditionsinclude; allergic eye disease, retinitis

pigmentosa, ocular rosacea, cone/roddystrophy and corneal granulardystrophy. Other bodily conditions wouldinclude eczema or hayfever, Down’sSyndrome, and connective tissuedisorders. Keratoconus has also beenlinked to forms of eye trauma includingcontact lens wear and eye rubbing.Diabetes has been shown to increase theseverity of the condition.

Normal cornealcurvature

Normalcross-linkingstructure

Reducedcross-linkingcausing weakness

Corneal bulging dueto Keratoconus

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“Having completed Topography Guided Ablation and Corneal CollagenCross-linking on both eyes, I am now 20:20 in the left eye after 7 weeksand my right eye is on course for a similar outcome.” Nick Pryce Jones


There is no cure for keratoconus andtreatment is therefore aimed at opticalimprovement. Depending on thedegree of corneal bulging, (ectasia)thinning of the cornea and resultantastigmatism a number of options canbe considered:

Contact LensesIn advancing cases of keratoconus, rigid(hard) contact lenses help to improvevisual acuity, yet they cannot stop theprogression of the condition.

Corneal Ring Segment Insert(Intacs)Clear plastic segments are placed into thecornea (pictured left). Intacs typically onlypartially correct the optical defect present,so additional optical aids or surgicalintervention may be required to obtain fullvisual correction.

Corneal TransplantationUp until a few years ago, the onlytherapeutic option for vision restorationin advanced cases of keratoconus wascorneal transplantation (penetratingkeratoplasty) to achieve better vision.

Corneal Collagen Cross-Linking A new minimally invasive procedure calledCorneal Collagen Cross-linking withRiboflavin (C3-R®) has now beendeveloped. This treatment uses acombination of Riboflavin drops and ultraviolet light that react with the tissues in thecornea, strengthening them by creatingmore 'cross-linking' among them. Theresulting increased stiffness and rigidity of

the cornea stabilises ectasia. Patients whopreviously had progressive ectasia havenow been treated and followed for up tofive years without evidence of any furtherchange in their condition.

POSSIBLE TREATMENT OPTIONS FOR KERATOCONUS�

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“The quality of vision thathas been achieved has farexceeded my expectation,and the less developed eyealready has remarkablygood vision only 2 weeksafter surgery.”Peter De’Ath


The aim of this treatment is tostabilise the cornea and prevent theprogression of keratoconus.

The main structure of the corneal tissue(stroma) consists of single collagen fibreswhich are linked. The treatment ofkeratoconus with collagen cross-linking isbased on a significant stiffening of thecorneal stroma due to photochemicalcross-linking of the single collagen fibres.Therefore the single fibres form a "densernetwork" which leads to an increase inthe overall stability of the cornea. Thisprocedure is performed under topicalanaesthesia.

After an epithelium abrasion (cornealscraping), Riboflavin (vitamin B) dropsare applied to the corneal surface over aperiod of 30 minutes and the cornea isthen exposed to 365nm UV for a 30minute period thereafter.

After the treatment a bandage contactlens is applied and a combination of asteroid and antibiotic drop is prescribed.During the follow up assessments of eyestreated with collagen cross-linking, veryfew patients showed further progression.

In approximately 80% of the patients aregression of the maximal K-values(regression of the keratoconus) has beenobserved. Post surgical corrected visualacuity improvement of 1 to 2 Snellen linescan be expected. No unwanted side effectssuch as opacification of the lens or loss ofendothelial cells has been reported.

Only during the first 2 to 3 months afterthe cross-linking has a minor superficialcorneal haze been observed. Generallythis minor haze disappears without anytreatment, but a supportive therapy withsoothing ointment or with local steroiddrops (i.e. FML or Prednisone) can beprescribed under supervision.

CORNEAL COLLAGEN CROSS-LINKING (C3R®) AT ACCUVISION�

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Post-op (C3R® with T-CAT) – improved cornealprofile with reduced irregular astigmatism

Pre-op topography – classic keratoconic features


In addition to ‘simple’ cross-linking,Accuvision can offer selected patientscombined corneal collagen cross-linking with corneal laser re-shaping.

This advanced treatment is designed toimprove central corneal symmetry, withoutattempting to correct other spherical, orregular astigmatic, optical defects.

Advanced Topography Guided (T-CAT) lasertreatment is kept to a small degree of tissueablation, with the maximum depth of tissueloss typically less than 50 microns. CornealCollagen Cross-linking with Riboflavin (C3-R®) treatment is applied immediately afterthe laser treatment. Any spherical or regularastigmatic, optical defect remaining afterthe combined AccuwaveTM T-CAT treatmentwith Corneal Collagen Cross-linking can becorrected subsequently by contact lens wearor by phakic intra-ocular lens implantation.

Potential risks of C3-R Treatmentfor KeratoconusUV light is known to be damaging to cells,and the keratoconus treatment causes thestromal cells (keratocytes) in the outerlayers of the treated parts of the cornea todie. However, these cells are replaced bynew keratocytes which migrate fromuntreated parts of the cornea into thecentral area over a period of some monthsafter the keratoconus C3-R® treatment. In theory the UV light could be damagingto the inner endothelial cell layer of thecornea, and this is why the cornealthickness needs to be at least 350 micronsif a standard keratoconus C3-R®treatment is to be undertaken. In clinicalstudies carried out so far, no evidence ofdamage to the endothelial cell layer hasbeen documented. Although UV ispotentially damaging to the lens andretina, it is believed that the riboflavinblocks the UV transmission to an extentthat no measurable damage will occur. Atpresent the long term effects of thekeratoconus treatment are unknown.

ACCUWAVETM TOPOGRAPHY GUIDED ADVANCEDCUSTOM ABLATION TREATMENT FOR KERATOCONUS (T-CAT)

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Pre-op (3D topography)

Post-op (3D topography) – demonstrating flatter,more regular profile

“I achieved 20:20 vision without lenses, which is a fantastic resulthaving had a -3.00 dioptre of astigmatism. The NHS told me therewas nothing they could do but prescribe glasses.” Christopher Jackson


RESULTS:

• All patients exhibited a reduction inirregular astigmatism

• Mean improvement in topographicalasymmetry was 7.8D

• Two thirds of patients had improvedBest Corrected Visual Acuity

• No patients lost Best CorrectedVisual Acuity

ACCUWAVETM TOPOGRAPHY GUIDED ADVANCEDCUSTOM ABLATION TREATMENT FOR KERATOCONUS (T-CAT)

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Patient

SMRSMLMGRGCRGCLSBRSBLPBRPBLIORIOLPJRPJLJORJOL

MWRLSRPPRPPL

Pre-Op

8D13D15D3D

8.5D5D8D7D

13D18D21D18D10D17D

14.5D11D6D9D7D

Post-Op

2.5D3D2D

1.5D0.5D3D

3.5D5D7D4D11D4D2D6D

2.5D6D2D0D3D

Improvement

5.5D10D13D1.5D8D2D

4.5D2D6D

14D10D14D8D

11D12D5D4D9D4D

Difference along steepest meridian: Gain / LossBCVA

(Snellen Lines)

+1=+3

+1/2+1=+1=+2+1

+1/2+4+1==+1=+1=

Using C3-R® and Topography Guided Custom Ablation our results show significant reduction inpre-op irregular astigmatism. D = Dioptre.


Due to the progressive nature ofkeratoconus, lifetime monitoring andcare is essential.

The corneal surface and biomechanicalproperties are first surgically stabilisedusing a combination of advancedTopography Guided Laser treatmentcombined with Riboflavin CornealCollagen Cross-linking. The resultanttopography (profile) is relatively normalisedand more symmetric. Hence post operativecontact lens fitting with improved tolerancebecomes a viable option. The focus whenfitting a keratoconic eye with a contact lensis on stable visual acuity with minimumlong term corneal stress and influence.

Often, there are many questions that areconsidered when a contact lens fit ismentioned post operatively. Some of themost common questions are addressedbelow:

Why can’t I wear glasses instead ofcontact lenses?It is possible to wear glasses, however thevisual acuity can be limited. Though thecorneal surface has been stabilised asmuch as possible, it is still relativelyirregular when compared to a ‘normal’eye. This means that a contact lens offersa much better quality of vision.

Why can’t I wear soft contact lenses?Soft lenses mould to the shape of the eyeand therefore mirror rather than mask anyirregularities in the corneal surface. A rigidlens creates a smooth surface that allowstears to flow more freely and thereforeimproves oxygen accessibility to thecornea. This offers the additional benefit ofa healthier eye even with long term orextended wear.

I have tried hard (Rigid Gas Permeable or RGP) lenses in the past and they were uncomfortable or gave poor vision or were difficult to handle. Why would this be different now?After treatment, the corneal surface is much more regular and therefore more responsive to a lens. This means that since the lens fit is enhanced, vision is improved and therefore patient satisfaction is much more likely. Additionally, the Accuvision Team is highly experienced and specialised in complex contact lens fits and this will ensure that patients are taught how to handle, care for and manage lenses on a personalised basis.

Please get in contact with the Accuvision team to discuss anything to do with keratoconus treatment on 0330 123 2020

C3-R® is a registered trademark of Boxer Wachler Vision Institute.

ACCUVISION LIFETIME AFTERCARE�

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LONDONAccuvision Laser Eye Clinics42-48 New Kings RoadFulhamLondonSW6 4LS

BIRMINGHAMAccuvision Laser Eye Clinics3 The Courtyard707 Warwick RoadSolihullBirminghamB91 3DA

LEEDSAccuvision Laser Eye Clinics1 Cromwell ParkYork RoadWetherbyLeedsLS22 7SU

ACCUVISION

Telephone: 0330 123 2020 www.accuvision.co.uk

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09.0013 keratoconus leaflet v2 - accuvision laser eye clinics keratoconus leaflet.pdf · what is...

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