Updates On Keratoconus

UPDATES ON

KERATOCONUSDR KHALED EL KHALED, MD, MRCOPHTH

SUBJECTS OF DISCUSSION FOR

ROUND TABLE

Introduction (clear definition of the disease)

Pathophysiology and Risk Factors (Genetic,

Environmental, etc.)

Diagnosis: slit lamp, clinical signs, topography, new

technologies (pentacam, ultrasound pachymetry) ..

Etc.

SUBJECTS OF DISCUSSION FOR

ROUND TABLE Clinical Signs; anatomical v-shape (pictures)

Topography in Diagnosis (early; moderate and advanced)

Spectacle correction (duration)

Contact lens (indications; types; duration; Rigid gas-permeable lenses)

Intrastromal corneal ring segments (FDA; indications; technics of surgery incision site; Segment type (mayorings..; number of rings.. Etc)

X-linking (FDA; indications; follow up)

ICRS + CXL {sameday} (then explantation of ICRS)

ICRS then PRK and CXL

Discussion: which to start; ideas

Topography-guided conductive keratoplasty (new procedure; indications.. etc)

Keratoplasty (PKP and DALK; indications; follow up)

PKP vs DALK; ideas

Keratoprosthesis (indications)

Boston 1 Keratoprosthesis vs repeated donor keratoplasty; ideas

Outcome; Conclusion and Message; Guidelines

Case reports and discussion

INTRODUCTION

ROUND HOT SPOT

OVAL HOT SPOT

SUPERIOR HOT SPOT

(SUPERIOR STEEP - SS)

INFERIOR HOT SPOT

(INFERIOR STEEP - IS)

IRREGULAR SHAPE

(STEEP AREAS ARE MIXED WITH FLAT AREAS)

SYMMETRIC BOWTIE

SYMMETRIC BOWTIEITH SKEWED

STEEPEST RADIAL AXIS INDEX

SB/SRAX. There is an angulation between segments’ axes. This angulation is

clinically significant when it is >22º

Asymmetric bowtie inferiorly Asymmetric bowtie superiorly

Asymmetric bowtie with Skewed Steepest Radial Axis Index

Claw pattern or the kissing birds patternButterfly

Junctional pattern Smiling face

Vortex pattern

AMSLER-KRUMEICH CLASSIfiCATIONStage Characteristics1-2-3-4

Stage 1

•Eccentric steepening Induced myopia and/or

astigmatism of ≤ 5.0 D

•K-reading ≤ 48.00 D

•Vogt's lines, typical topography

Stage 2

•Induced myopia and/or astigmatism between 5.00

and 8.00 D

•K-reading ≤ 53.00 D

•Pachymetry ≥ 400 µm

Stage 3

•Induced myopia and/or astigmatism between 8.01

and 10.00 D

•K-reading > 53.00 D

•Pachymetry 200 to 400 µm

Stage 4

•Refraction not measurable

•K-reading > 55.00 D

•Central scars

•Pachymetry ≤ 200 µm

Stage is determined if one of the characteristics applies.

Corneal thickness is the thinnest measured spot of the cornea.

1Krumeich JH, Kezirian GM (April 2009). "Circular keratotomy to reduce astigmatism and improve vision in stage I and II keratoconus". J. Refract. Surg. 25 (4): 357–65.

2Krumeich JH, Daniel J (August 1997). "Lebend-Epikeratophakie und Tiefe Lamelläre Keratoplastik zur Stadiengerechten chirurgischen Behandlung des Keratokonus (KK) I-III" [Live epikeratophakia and deep lamellar keratoplasty for I-III stage-specific surgical treatment of keratoconus]. Klin. Monbl. Augenheilkd. (in German) 211 (2): 94–100.

3Alió JL1, Shabayek MH. Corneal higher order aberrations: a method to grade keratoconus. J Refract Surg. 2006 Jun;22(6):539-45.

4Kératocõne classique et kératocône fruste; arguments unitaires.

Four map composite display (sagittal curvature, anterior and posterior elevation, and corneal thickness). This cornea shows a significant positive island of elevation

(ectasia) on the posterior cornea (right lower map) in spite of a normal anterior surface (upper right and left map)

Four map composite display (sagittal curvature, anterior and posterior elevation, and corneal thickness). This cornea shows a significant positive island of elevation

(ectasia) on the posterior cornea (right lower map) in spite of a normal anterior surface (upper right and left map). In this example, the posterior ectasia is significant

enough to cause a displacement of the corneal thinnest point (lower left)

Belin/Ambrosio enhanced ectasia display. The display shows abnormalities in all

major parameters except those for the anterior corneal surface. Because the

anterior surface is still within normal limits, the patient would have good

spectacle vision in the presence of (subclinical) keratoconus

Belin/Ambrosio enhanced ectasia display. The display depicts a case of moderately

advance keratoconus where all the analyzed parameters (anterior and posterior

elevation, Kmax, and pachymetric parameters) are highly abnormal

Composite map showing anterior curvature upper left, corneal thickness lower left, anterior elevation

upper right, and posterior elevation lower right. The axial curvature map incorrectly locates the "cone"

near the periphery, while both the elevation maps and pachymetric map correctly reveals this as a case of

inferior keratoconus

Corneal thickness map of a true case of pellucid marginal degeneration. The

pachymetric map opened up to a full 12 mm view is the best map to differentiate

true pellucid from inferior keratoconus, as true pellucid will show a clear band of

corneal thinning near the inferior limbus

EPIDEMIOLOGY

There are a wide range of prevalences reported in

the general population, ranging from 50 to 230 per

100,000.

There is no difference in incidence and prevalence

between genders1-3.

1. Krachmer JH, Feder RS, Belin MW. Keratoconus and related noninflammatory corneal thinning disorders. Surv Ophthalmol 1984; 28:293.

2. Kennedy RH, Bourne WM, Dyer JA. A 48-year clinical and epidemiologic study of keratoconus. Am J Ophthalmol 1986; 101:267.

3. Rabinowitz YS. Keratoconus. Surv Ophthalmol 1998; 42:297.

RISK FACTORS

Systemic disorders

Environment

Eye-rubbing1

Contact lens use

Family history: This disorder has weak penetrance

and significant variability of expression.

1. Sugar J, Macsai MS. What causes keratoconus? Cornea 2012; 31:716.

GENETIC FACTOR

PATHOPHYSIOLOGY

Keratoconus is a noninflammatory disorder of the

cornea of unknown etiology.

Keratoconic corneas have a decrease in the content

of collagen compared with normal corneas.

PATHOPHYSIOLOGY

CLINICAL FEATURES

Asymmetric visual complaints

Difficulty with visual correction

Munson's sign

Corneal hydrops

MUNSON'S SIGN

CORNEAL HYDROPS

DIAGNOSIS

Difficulty correcting a patient’s vision to 20/20

visual acuity

Fleisher ring

Vogt striae

Central and inferior paracentral corneal thinning

Corneal scarring

FLEISHER RING

VOGT STRIAE

CORNEAL SCARRING

OPHTHALMIC TECHNIQUES

Retinoscopy: Scissoring reflex: early sign

Keratometry

Corneal topography

RETINOSCOPY: SCISSORING

REFLEX: EARLY SIGN

KERATOMETRY

CORNEAL TOPOGRAPHY

DIAGNOSIS

MANAGEMENT

Spectacle correction

Contact lens: Rigid gas-permeable lenses

Surgical treatments

Intrastromal corneal ring segments

Corneal collagen cross-linking

Keratoplasty

SPECTACLE CORRECTION

CONTACT LENS

INTRASTROMAL CORNEAL RING

SEGMENTS

Approved by the US Food and Drug Administration

(FDA) in 2004 for the management of Keratoconus.

Thin, semi-circular plastic inserts are implanted into

the mid-corneal layers to flatten the cornea.


SEGMENTS

CORNEAL COLLAGEN CROSS-

LINKING


LINKING

Corneal collagen cross-linking using riboflavin and

UV received FDA approval on April 18, 2016.


LINKING


SEGMENTS


LINKING

TOPOGRAPHY-GUIDED

CONDUCTIVE KERATOPLASTY

KERATOPLASTY (CORNEAL

TRANSPLANTATION)

The procedure of choice when contact lenses are no longer helpful

Approximately 10 to 15 percent of patients with keratoconus will require Keratoplasty

Penetrating keratoplasty (full thickness corneal transplant) is the most commonly used procedure1-2.

Deep anterior lamellar keratoplasty (partial thickness corneal transplant) is another option

This procedure has a success rate of greater than 90 percent in patients with keratoconus3.

1. Gordon MO, Steger-May K, Szczotka-Flynn L, et al. Baseline factors predictive of incident penetrating keratoplasty in keratoconus. Am J Ophthalmol 2006; 142:923.

2. Keane M, Coster D, Ziaei M, Williams K. Deep anterior lamellar keratoplasty versus penetrating keratoplasty for treating keratoconus. Cochrane Database Syst Rev

2014; 7:CD009700.

3. Sharif KW, Casey TA. Penetrating keratoplasty for keratoconus: complications and long-term success. Br J Ophthalmol 1991; 75:142.

PENETRATING KERATOPLASTY

PKP

DEEP ANTERIOR LAMELLAR

KERATOPLASTY DALK

KERATOPLASTY (CORNEAL

TRANSPLANTATION)

KERATOPROSTHESIS

OUTCOME

CONCLUSION During early stages, vision can be corrected with eyeglasses.

As the condition progresses, rigid contacts may need to be worn so that light entering the eye is refracted evenly and vision is not distorted.

You should also refrain from rubbing your eyes, as this can aggravate the thin corneal tissue and make symptoms worse.

Keratoconus can also be treated with Intacs, Intacs are FDA approved.

Another treatment option for keratoconus that is not FDA approved is collagen cross-linking.

When good vision is no longer possible with other treatments, a corneal transplant may be recommended.

Another type of cornea transplant that is becoming more popular as a treatment for keratoconus is called DALK, or Deep Anterior Lamellar Keratoplasty.

Artificial cornea can be a solution after many rejections.

NICE GUIDELINE

THANK YOU

Updates On Keratoconus

Health & Medicine

Transcript of Updates On Keratoconus