KeratoconusPAVAN

DEFINITION

• Progressive,• Non inflammatory,• Bilateral (usually asymmetrical)• Cone like anterior protrusion of the cornea

involving the central and the inferior paracentral areas that results in corneal ectasia, astigmatism, & decreased vision.

• Incidence of 1 in 2000 of general population.

DOS Times - Vol. 15, No. 10, April 2010

• Usually seen after puberty• No gender predominance• No race predominance• The patient becomes myopic but the error

of refraction cannot be satisfactorily corrected with ordinary glasses owing to parabolic nature of the curvature which leads to irregular astigmatism.

• sub clinical keratoconus is seen in family members or the fellow eye.

• No frank clinical sign• The cornea is at risk of developing

keratoconus at a later stage and can be diagnosed only by videokeratography.

DOS Times - Vol.10, No. 7 January 2005

• Classifaication BY krumeich based on astigmatism, & thichness..• Stage 1: Eccentric corneal steapening • induced myopia or astigmatism -5D• corneal radii 48D• Vogts sriae, no scar• Stage 2: • induced myopia or astigmatism -5D to -8D• corneal radii 48D• Vogts sriae, no scar• Corneal thickness 400 ums• stage 3: induced myopia or astigmatism -8D to-10D• corneal radii 53D• Vogts sriae, no scar• Corneal thickness 200 to 400 ums• Stage 4: reraction not measurable• corneal radii 55D• corneal scars+, perforations+• Corneal thickness 200 ums•

• B: Based on keratometry• mild <48D• moderate 48 -54D• severe: >54D• C: Based on morphology• nipple cones(central <5mm)• oval/sagging cones(5-6mm)• globus cones(>6mm)

Etiology• Various theories:- • Thinning may be due to• Defective formation/destruction of extracellular

matrix• Abnormal collagenase activity.• Increased levels of proteases &catabolic

enzymes in the basal epithelial cells• Decreased levels of proteinase inhibitors: alpha 1 proteinase inhibitor , alpha 2 macroglobulin.

• Excessive eye rubbing or atopic disease-• induces keratoconus by inducing • epithelial damage-----• epithelial stress----• increased keratocyte apoptosis through

interluekin 1 causing changes in stomal matrix

• Hard contact lens wear • 6-15 % positive family history.

• The role of heredity not been clearly established. .

• In some cases, however, • a sex-linked • autosomal dominant mode of inheritance,

particularly because of the predominance of familial females with keratoconus.

Systemic associations• Atopy • Down syndrome• Turner syndrome• Ehlers –danlos syndrome• Marfans syndrome• Osteogenesis imperfecta• Floppy eyelid syndrome• Oculodentodigital syndrome• Rieger's syndrome • Focal dermal hypoplasia• Nail -patella syndrome• Apert's syndrome• craniofacial dysostosis (Crouzon's syndrome)

Crouzon syndromeMarfan syndrome Osteogenesis imperfecta

Atopic dermatitis Down syndrome Ehlers-Danlos syndrome

Ocular association• Vernal keratoconjunctivitis• RP• Leber’s congenital amaurosis• Retinopathy of prematurity• Progressive cone dystrophy• Aniridia • Iridoschisis • Iris atrophy• Fuchs' dystrophy• Posterior polymorphous dystrophy• Granular and lattice dystrophies

Histopathology• Triad of classical histopathologic features

– Thinning of the corneal stroma– Breaks in Bowman’slayer – Deposition of iron in the basal layersof the

corneal epithelium

Depending on the stage of the disease, every layer and tissue of the cornea can become involved

• The epithelium may show degeneration of its basal cells, breaks accompanied by down growth of epithelium into Bowman’s layer

• Accumulation of ferritin particles within and between epithelial cells most prominently in the basal layer of the epithelium.

.

• Bowman’s layer may include breaks

• filled by eruptions of underlying stromal collagen, periodic acid Schiff–positive nodules.

• Z-shaped interruptions, possibly due to separation of collagen bundles and reticular scarring.

• In stroma changes seen are compaction and loss of arrangement of fibrils in the anterior stroma

• decrease in the number of collagen lamellae

• normal and degenerating fibroblasts in addition to keratocytes,

• fine granular and microfibrillar material associated with the keratocytes.

• Descemet’s membrane is rarely affected except for breaks seen in acute hydrops.

• The endothelium is usually normal. However, some abnormalities like

• intracellular “dark structures,”• pleomorphism, and elongation of cells with

their long axis toward the cone.

Symptoms

• Progressive visual blurring and/or distortion• Rapidly changing spectacle prescription • Eye rubbing• Photophobia• Glare• Monocular diplopia• Sudden onset of pain, redness, loss of

vision, and photophobia suggests hydrops

• The onset of keratoconus occurs predominantly in the late teens.

• Symptoms usually appear bilaterally, but asymmetric presentation.

• During the first 5-7 years of onset, the condition generally worsens with intermittent periods of remissions

SIGNS KKKKKK

• Munson’s sign is a V-shaped conformation of the lower lid produced by the ectatic cornea in downgaze.

• Rizzuti’s sign is a sharply focused beam of light near the nasal limbus, produced by lateral illumination ofthe cornea in patients with advanced keratoconus.

• Charleux”s sign: Dark reflex in the centre of cornea with DDO in dilated pupils..

• Pulsations of mires on applanation tonometry• Pulsations of reflected images in keratometry.

Slit lamp examination

• Prominent corneal nerves

Slit lamp examination• Fleischer's Ring

– The Fleischer ring is a yellow-brown to olive-green ring of pigment which may or may not completely surround the base of the cone

– Formed when hemosiderin (iron) pigment is deposited deep in the epithelium

– Fleischer's ring often becomes thinner and more discrete with progression

• seen approximately 50% of all cases.• Locating this ring initially may be made

easier by using a cobalt filter and carefully focusing on the superior half of the cornea's epithelium.

• Imp : gives information about extent of ectasia, which helps during surgery & prognosis after P.K..

Lines of Vogt

• small and brushlike lines, generally vertical but they can be oblique.

• Found in the deep layers of the stroma and form along the meridian of greatest curvature.

• Disappear when gentle pressure is exerted on the globe through the lid.

Corneal Thinning:

• Significant thinning (up to 1/5th cornea thickness) in the advanced stages of the disease and

• A diagnostic criterion based on comparison of central and peripheral corneal thickness has been proposed.

• Additionally, as the disease progresses, the cone is often displaced inferiorly.

• The steepest part of the cornea (apex) is generally the thinnest.

Corneal Scarring

• Sub-epithelial corneal scarring, not generally seen early, may occur as keratoconus progresses because of ruptures in Bowman's membrane which is then filled with connective tissue

• Deep opacity of the cornea are also common in keratoconus.

Corneal Hydrops:

• Corneal hydrops occurs in advanced cases,

• when Descemet's membrane ruptures, aqueous flows into the cornea and reseals

• Keratoconus patients who are having an acute episode of corneal hydrops report a sudden loss of vision and a visible white spot on the cornea.

• Corneal hydrops causes edema and opacification.

• As Descemet's regenerates, edema and opacification diminish.

• Occasionally, hydrops can benefit keratoconus patients who have extremely steep corneas.

• If the cornea scars, a flatter cornea often results, making it easier to fit with a contact lens.

• An increased incidence of hydrops has also been reported in keratoconus patients with Down's syndrome.

Diagnosis• Early keratoconus usually manifests as a small

island of irregular astigmatism in the inferior paracentral cornea.

• As the cornea bulges outward, the amount of astigmatism increases due to the progressive distortion of the corneal surface.

• These changes can easily be seen as irregular mires on keratometry readings and on corneal topography, a test used to map the topographical surface area of the cornea

• Many objective signs are present in keratoconus.

• Retinoscopy shows a scissoring reflex.• Direct ophthalmoscopy may show a

shadow If the pupil is dilated and a +6.00 D lens is in the ophthalmoscopic system, the cone may appear as an oil or honey droplet when the red reflex is observed-Charleux” oil droplet sign

• The photokeratoscope or topographer placido disc can provide an overview of the cornea and can show the relative steepness of any corneal area.

• The even separation of the rings in the spherical cornea ".

Placido disc

• In astigmatic cornea uneven spacing of the rings--especially inferiorly--in the keratoconic cornea should be noted

• . The central rings may show a tear-drop configuration termed "keratokyphosis".

DOS Times - Vol.10, No. 7 January 2005

• The keratometer also aids diagnosis. • The initial keratometric sign of

keratoconus is absence of parallelism and inclination of the mires. These can easily be missed in mild or early cases.

Rabinovitz criteria for diagnosis of keratoconus

1. Central corneal power >47.2D2. Inferior superior dioptric assymetry over

1.23. Sim K astimatism >1.5D4. Skewed radial axes more than 21

degrees

Corneal topography

• Provides a color coded map of the corneal surface.

• The power in diopters of the steepest and flattest meridians and their axes are calculated and displayed

• Steep curvatures are marked orange or red

• Flat curvature in blue or violet• Normal curvatures in green or yellow

Classification scheme of normal videokeratographsin the absolute scale devised as a baseline to monitortopographic progression to keratoconus A, round:B, oval: C, superior steepening; D, inferior steepening; E,irregular; F, symmetric bow tie; G, symmetric bow tie withskewed radial axes; H, asymmetric bow tie with inferiorsteepening (AB/IS); I, asymmetric bow tie with superiorsteepening; J, asymmetric bow tie with skewed radial axes(AB/SRAX

• Two figures are a schematic illustration of how to determine whether a pattern is AB/IS or AB/ SRAX.

• A line is drawn to bisect the upper and lower lobes of the asymmetric bow tie,

• If there is no significant deviation from the vertical meridian (i.e., no skewing), the pattern is designated as AB/IS (as in A);

• if the lines bisecting the two lobes appear skewed by more than 21 degree from the vertical meridian (i.e., 150 deg from one another), it is labeled as AB/SRAX (as in Bottom B).

Corneal topography

asymmetric bow tie with a skewed radial axis.

Corneal topography• Rabinowitz developed algorithms for detection of

keratoconus based on 3 observations• Diopteric power difference between the sup and inf

paracentral cornea I/S >1.9• Central corneal power >48.7 D • Difference in progression of corneal steepening

between two eyes• Method yeilds positive result In case of keratoconus

suspect- • if I/S value is >1.4 and central corneal power

>47.2D.

INDICES

• SIM-K (MAX &MIN)• APICAL POWER• ASTIGMATIC INDEX• IRREGULARITY INDEX• ANTERIOR ELEVATION• POSTERIOR ELEVATION• INF –SUP ASYMETRY

• SIMULATED K READINGS:• Corneal curvature In the central 3 mm area• Steep sim-k reading in 3 mm indicates steepest

meridian, & flattest will be 90* apart to this.• SURFACE ASSYMETRY INDEX:• Indicates changes in curvature of cornea from

centre to peryphery,• Normally cornea is prolate, with ashperycity-

0.26, but in K.C it becomes oblate with positive aspherycity value

• IRREGULARITY MAP: it displays the distortions of cornea using previous elevation map, & represents with hot colours…

• ANTERIOR ELEVATION:• with BFS: to locate the cone• WITH BFTE(best fit torric ellipsoid): to

check the real height of the cone• Red indicates raised, & blue flat.

normal K.C suspect K.C

Central k reading

44.17 45.13 48.97

I-S assyemtry 0.57 1.20 4.4

KISA INDEX

• INCLUDES FOUR COMPONENTS• K READINGS• I-S ASSYMETRY• ASTIGMATISM INDEX• SRAX• KISA=K x I-S x AST x SRAX x 1/3• 100% =KERATOKONUS• 60-100% =SUSPECT• <60% = NORMAL

D’DS

• PELLUCID MARGINAL DEGENERATION• TERRIENS DEGENERATION• POSTERIOR KERATOCONUS• KERATOGLOBUS

TREATMENT OPTIONS• Spectacles & soft contact lenses

– RGPs – 3 point touch technique– Soper lenses, Mc Guire lenses, Rose K lenses– Softperm lenses – hybrid lenses– Piggy back lenses

• INTACS, CXR

• TPRK / TORIC IOL / PHAKIC IOL

• Keratoplasty – PK, DALKKeratoplasty – PK, DALK

Spectacles

• Mild keratoconus can be corrected with spectacles.

• Retinoscopy is difficult;

• a normal subjective refraction is required.

• Monocular keratoconus is usually best dealt with using spectacle correction.

TREATMENT PROTOCOL

• Stage i– Stop progression– C3R

• Stage ii– Visual rehabilitation– INTACS (Centralise the cone)– ICL– CL (RGP / SOFT /

COSTOMISED)- TPRK (Topo guided PRK)

Contact lenses

• Contact lenses are considered when vision is not correctible to 6/9 by spectacles and patients become symptomatic.

• Rigid gas permeable (RGP) corneal lenses are the lenses of first choice.

• The aim is to provide the best vision possible with the maximum comfort so that the lenses can be worn for a long period of time.

• Based on shape of cone• Nipple cone : small diameter (5 mm.); round

shape; easiest to fit with contact lenses

• Oval large diameter(>5 mm.); often displaced inferiorly; more difficult to fit with lenses

• Globus largest diameter (>6 mm.); 75% of cornea affected; most difficult to fit with lens

• Nipple cone oval cone globus

Fitting methods • 1) Three-point-touch design• Contact at the central apical area & two

horizontal mid periphery area at 3 & 9’ -0 clock position.

• The three-point-touch design is the most popular and the most widely fitted design

• The aim is to distribute the weight of the contact lens as evenly as possible, between the cone and the peripheral cornea.

• The ideal fit should show an apical contact area of 2-3mm with mid-peripheral contact.

• Adequate edge clearance is required to ensure tear exchange.

2) Apical clearance • In this type of fitting technique:• the lens vaults the cone and clears the central

cornea, resting on the paracentral cornea.

• These lenses tend to be small in diameter and have small optic zones

• The potential advantages of reducing central corneal scarring are outweighed by the disadvantages like poor tear film, corneal oedema, and poor visual acuity as a result of bubbles becoming trapped under the lens.

• 3) Flat fitting• The flat fitting method places almost the entire weight of

the lens on the cone. • The lens tends to be held in position by the top lid. • Good visual acuity is obtained as a result of apical touch.• Alignment can be obtained in early keratoconus; • however, flat fitting lenses can lead to: - progression/ acceleration of apical changes and

corneal abrasions. • This type of fitting is useful where the apex of the cone is

displaced.

• Piggy back lenses can be used in pts who are uncomfortable with RGP wear.

• And in pts who are more prone to epithelial erosion at apex of cone.

ROSE-K• Introduved by Paul rose, & k means keratoconus .• specially designed for kearatoconic eyes with a diagnostic

set of 26 lenses with base curves ranging from 5.1 to 7.6 mm in 0.1 increments,

• A std lens diameter is 8.7mm.• Features .• Customized complex geometry suitable in correcting high

myopia & astigmatism.• Easy to insert & remove.• Provide excellent health to eye.• Good oxygen permeability.

• Rose –k lenses have more curves on back surface of lens, in such a way that adjacent curves are very different from each other,

• Causes different focal points for each curve

• Leads to more aberrations

• To overcome this problem he introduced rose –k2 lenses in 1998, which are having small changes in curves in both front & back surface of the lens

Soper lens

Custom made lens Two zones in the posterior curvature. Central zone : to vault steep central

cornea .It is of varying steepness depending of the patients cornea.

Peripheral zone is with a 45D curvature designed to vault the mid periphery and limbal cornea

MAC-GUIRE LENSES

• Modified sooper lenses

Scleral lenses

• Scleral lenses play a very significant role in cases of advanced keratoconus where corneal lenses do not work and corneal surgery is contra-indicated.

• Scleral lenses completely neutralise any corneal irregularity and can help patients maintain a normal quality of life

Boston scleral lens prosthetic device (BSLPD)

• Fluid ventilated scleral lens• Designed to enclose a bubble free

reservoir of fluid over the corneal surface• Series of breaches are created between

haptic bearing surface of the lens and underlying sclera.

• This will facilitate the aspiration of surface tears into the reservoir so that intrusion of air bubble during a blink is prevented.

• Shape of haptic confirms exactly to that of underlying sclera to maintain functionality and prevents intrusion of air bubbles.

• Very expensive

Collagen cross linking by riboflavin and UVA

• Photopolymerisation of collagen fibers by photosensitizing substance like(riboflavin or vit b2)+uv type a rays from a solid state UV source

• Indications– Progressive keratoconus – Eyes with mild to moderate keratoconus – Corneal thickness > 400 µm – No slit-lamp evidence of corneal scarring– Preferably age < 35 yrs since complication rate

increases after 35yrs

Combining UV radiation and riboflavin is the most effective method to induce collagen cross linking.

STEPS• Using topical anaesthesia,

• 7mm circle is marked on the cornea using a marker.

• Epithelium of the marked area is scraped off using a blunt spatula.

• A corneal abrasion is created to facilitate riboflavin diffusion into the cornea.

• One drop of riboflavin 0.1% and 20% dextran ophthalmic solution is instilled topically in the eye every 2 minutes for 30 minutes.

• After 30-minute, the eye is examined with blue light for the presence of a yellow flare in the anterior chamber, indicating adequate riboflavin saturation of the corneal tissue.

• When the yellow flare in the anterior chamber is confirmed,

• the eye is aligned under the UV-A light .

• Focussed on the apex of cornea at a distance of 10-12m to obtain a radiant energy of 5.4J/cm2 for 5 min.

• The correct aperture setting is selected for the size of the eye;

• the eye is irradiated for 30 minutes, during which time instillation of riboflavin is continued (one drop every 5 minutes).

Issue: February 2009Collagen Cross-linkingWhat you should know about this potential newtreatment for keratoconus and ectasia.BY YARON S. RABINOWITZ, M.D.

• After completion of the procedure,eye is washed with BSS , an antibiotic drop is instilled and a bandage contact lens is applied.

• The contact lens is removed once the abrasion has healed.

• Postoperative medications include an antibiotic and a steroid for 2 weeks postoperatively.

• There are reports of the procedure being performed without removing the epithelium.

• This is attractive to patients since they would forgo the pain caused by the abrasion, as well as decrease their risk for infection due to an open wound.

• Bottos et al. demonstrated that the epithelium is a barrier to crosslinking and very little cross-linking occurs in the presence of epithelium showed by immunofluorescent confocal microscopy studies.

• These findings suggest that for the treatment to be effective, the epithelium should always be removed

Results • The procedure appears to be relatively safe. • The only adverse event reported to date after cross-

linking has been corneal edema in an eye with a pretreatment corneal thickness of less than 400 microns, presumably caused by UV damage to the corneal endothelium

• Subsequent experiments led to the conservative recommendation that corneas not be treated with UVA/riboflavin unless they are thicker than 400 microns after epithelial debridement. Thus preop pachy is very imp.

• Other complications reported in the literature are a case of HSV keratitis and DLK in a case of post-LASIK ectasia. Both resolved without any long term-effects on the patients

Ophthalmology Management Issue: February 2009Collagen Cross-linking - potential new treatment for keratoconus and ectasia.BY YARON S. RABINOWITZ, M.D.

Complications of C3R

• Corneal haze• Diffuse lamellar keratitis• Reactivation of viral keratitis and iritis• Infective keratitis• Corneal scarring• Persistent corneal edema• Corneal melt

Intracorneal stromal rings

• Act as passive spacing agents which flatten the cornea

• Made of PMMA• Amount of correction depends on the ring

thickness,more thicker the ring more correction.• On insertion they shorten the arc of ant corneal

surface,iron out gross irregularities and in effect create a second limbus.

• Various corneal ring- Ferarings, intacs.

• An important potential benefit of treating keratoconus with INTACS inserts is to delay or eliminate the need for a corneal graft.

• Patients with mild to moderate keratoconus appear to be the best candidates.

• Thickeness varies from 0.21mm to 0.45mm -Selection of intacs depends on :: -Pre op manifest refraction -Location of cone -Amount of astigmatism -Spherical eqvivalent

INDICATIONS

• This procedure is good for patients:– contact lens intolerant – Whose central cornea is clear– K readings are not in excess of 58 Diopters– > 400 microns– To Patient where only corneal transplantation is

the remaining option.

• under topical anesthesia,• a small corneal incision (1.8 mm in length)

was made temporally at the edge of the 7-mm optical zone

• Two intrastromal tunnels (clockwise and counterclockwise) were created.

• Special care was taken when making the Inferior tunnel, where the cornea is relatively thinner.

• a 0.45-mm INTACS insert was placed inferiorly to lift the conus, and

• a 0.25-mm INTACS insert was placed superiorly to flatten the cornea and decrease baseline keratoconic asymmetric astigmatism.

• The selection of segments is based on std normograms

• In globus or central cone-2 rings of equal thickness

• Assymetrical cone-thin in flatter and thick in steeper-usually inferior.

• The corneal wound was gently hydrated during INTACS inserts placement, and edges of the stroma were approximated to prevent epithelial ingrowth.

• The incision was closed with one 10–0 nylon suture.

• A topical antibiotic/steroid combination was applied postoperatively and a clear shield put on the eye for recovery.

• The suture was removed 1 to 4 weeks after the surgery,

Complicationsof INTACS

• Undercorrection-residual myopia-thicker rings in steeper area

• Overcorrection-if pt hyperopic thin ring can be exchanged

• Migration of rings• Extrusion or progressive thinning• New vessel formation• glare /halos

Contraindications

• Collagen vascuar diseases• Autoimmune/immunodeficiency diseases• Pregnant / nursing mother,• Ocular conditions such as recuurent

corneal errosion syndromes/dystrophy• Whose pupillary diameter more than 7mm• Patients on isoretinoin , sumatriptan,

amiodarone

• Combination of INTACS & C3R can be done

Phakic iols• Used to correct high myopia and

associated astigmatism of selected keratoconus patients.

• Anterior chamber phakic intraocular lens have also been combined with intacs with good results.

• The INTACS implantation is followed by toric phakic intraocular lens implantation

to correct the residual myopic and astigmatic refractive error.

PHAKIC IOLS • INCLUSSION CRITERIA:• Stable refractive error for more than one year• Clear central cornea• Central dioptric power should be less than 52D

• EXCLUSSION CRITERIA:• Central ant chamber depth less than 2.8mm• Endothelial cell count less than 2000/mm2• Patient younger than 21years

Penetrating Keratoplasty

• The gold standard surgery• Success rate is more than 90%.• In this procedure, the keratoconic cornea

is prepared by removing the central area of the cornea, and a full-thickness corneal button is sutured in its place.

• Usually trephines between 8.0-8.5 mm are used.

• Fleischer’s ring can be used as the limit of the conical cornea.

• Contact lenses are often required after this procedure for best visual rehabilitation.

Anterior deep lamellar kearatoplasty

• Partial corneal transplant. • The cornea is removed to the depth of posterior stroma,

and the donor button is sutured in place. • This technique is technically difficult, and visual acuity is

inferior to that obtained after penetrating keratoplasty. • As a result, use of lamellar keratoplasty is largely

confined to the treatment of large cones or keratoglobus when tectonic support is needed.

• This technique requires less recovery time, and poses less chance for corneal graft rejection or failure.

• Its disadvantages include vascularization and haziness of the graft

Thermokeratoplasty

• Rare procedure• It involved placing a hot ring (Holmium yag

laser, 2100nm) along the base of the cone to heat and traumatize the cornea, resulting in a corneal scar which reduces the corneal curvature.

• It allows a flatter contact lens to be fitted..

• The disadvantages of the procedure• transitory corneal haze • development of corneal scarring

DOS Times - Vol. 14, No.1, July 2008

• STUDY :Penetrating and Deep Anterior Lamellar Keratoplasty for Keratoconus: A Comparison of Graft Outcomes in the United Kingdom

• PURPOSE. To compare outcomes after penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) for keratoconus in the United Kingdom.

• METHODS. Patient outcome data were collected at the time of transplantation and at 1, 2, and 5 years after surgery.

RESULTS.• The risk of graft failure for DALK was almost twice that

for PK • Nineteen percent of the DALK failures occurred in the

first 30 postoperative days compared with only 2% of PK failures.

• there was little difference between the 3-year graft survivals for DALK and PK Although the mean best corrected visual acuity (BCVA) was similar for the two procedures.

• 33% of patients who underwent PK achieved a BCVA of 6/6 or better at 2 years compared with only 22% of those who underwent DALK )

• Those with DALK were also likely to be more myopic ( 3 D) but there was little difference in scalar cylinder.

• CONCLUSIONS.• DALK had a higher overall failure rate than PK.• The difference was largely accounted for by

early failures, which appeared to be related to the surgeon’s experience.

• DALK recipients were less likely to achieve BCVA of 6/6 than were PK recipients and were more likely to have 3 D or worse myopia.

(Invest Ophthalmol Vis Sci. 2009;50:5625–5629)DOI:10.1167/iovs.09-3994

GENERAL GUIDELINE

>40 Yrs – Toric IOL

Decentered coneCentered cone Advanced KC

KERATOCONUS (KC)

>5MM <5MMDALK / PK

ProgressiveStable

CL / ICL

>40 Yrs

Toric IOL

C3R / INTACS

Toric ICL

C3R

<55D >55D

CL / ICL

GENERAL GUIDELINE

Toric IOL

Decentered coneCentered cone Advanced KC

KERATOCONUS (KC)

>5MM <5MM

Stable Progressive

CL / ICL

INTACS +C3R

< 450 microns ORA good

TPRK + C3R

INTACS

> 450 microns ORA poor

• THANK YOU