all about your cornea: corneal & refractive diseases & treatments

All About Your Cornea: Corneal & Refractive Diseases & TreatmentsJennifer Nottage, MD

www.SpringfieldClinic.comwww.SpringfieldClinic.com

Anatomy of the Eye

Anatomy of the Cornea

Epithelium

Bowman’s

Stroma

Descemet’s

Endothelium

Nearsighted Farsighted

Astigmatism

Types of Corneal Surgeries

• Refractive procedures:– LASIK– PRK– RK– Intacs– Implantable CL– Clear lens exchange

• Medical procedures:– PK– DSEK– DALK– Keratoprosthesis

Refractive Procedures

Am I a candidate for Refractive Surgery?

To be a candidate for Refractive Surgery, you must:

• Be at least 18 years old. This age requirement is necessary to ensure the eyes have finished growing.

• Have mild to moderate nearsightedness (myopia), farsightedness, or astigmatism.

• Be free of eye disease including problems with the retina or scarring of the cornea.

• Have the financial ability to pay for the cost of surgery since insurance may not cover the procedure.

• Be aware of all the side effects, risks, benefits, and alternatives of the surgery.

Refractive Surgery

• LASIK (laser in-situ keratomileusis)• PRK (photorefractive keratectomy)• RK (radial keratotomy)• Intacs• Clear lens exchange• Implantable contact lens

RK

• Radial keratotomy• Correct nearsightedness• Procedure involves making radial incisions

in the cornea to alter the curvature.• Outcomes are variable.• The procedure can weaken the structural

integrity of the cornea.• Rarely preformed at this time.

LASIK

LASIK

• Used to correct nearsightedness, farsightedness, and astigmatism.

• Reshaping the cornea using an excimer laser.– A flap of tissue if formed using either a blade or a laser.– The laser is then preformed to remove tissue and the flap

is repositioned. • Wavefront guided LASIK

– Also called custom LASIK– Allows for the LASIK procedure to be tailored to each

patient which can increase the quality of vision.• “All laser LASIK”

LASIK

• Recovery:– Fast with minimal discomfort– Limited time off of work

• The vision usually stabilizes between 3-6 months after LASIK surgery.

• Post-operative care is usually limited to using eye drops for a few weeks after surgery.

• The eye is not weakened because only one flap is cut into the cornea (compared to RK).

• LASIK usually causes little or no scarring of the cornea.• LASIK can be repeated if needed to correct the vision

further.

LASIK- Possible Side Effects

• Eye discomfort (mostly during the first 24 hours following surgery)

• Dry eyes (during the healing process)• Overcorrected or undercorrected vision• Blurry vision or vision loss• Irregular astigmatism, which can decrease the corrected

vision• Corneal haze, glare, or sensitivity to light• Corneal scarring• Inflammation or infection• Inability to wear contact lenses in the future• Loss of the corneal flap, requiring a corneal graft

PRK

PRK

• Used to correct nearsightedness, farsightedness, and astigmatism.

• Reshaping the cornea using an excimer laser.– The epithelium (outer layer of the cornea) is

removed.– The laser is then preformed to remove tissue– A contact lens is placed over the cornea– The epithelium will heal slowly

PRK

• Recovery– 2-4 weeks for the cornea to heal – Mild corneal haze– Glare/halos– The eye is not weakened because a flap is

not created in the cornea(compared to RK).• Side effects

– Similar to LASIK

Clear lens exchange

• Same procedure as cataract surgery but the lens is not opaque

• Same risks of cataract surgery• Loss of accommodation

– But may have a bifocal lens placed (ReSTOR, ReZoom)

• No glare/halos

Implantable Contact Lens

• Also called Phakic IOL (intraocular lens)• Two options in the US

– Visian ICL• Placed behind the iris

– Verisyse• Attaches to the iris

• Can be used in cases when patients are not LASIK or PRK candidates, such as:– High amounts of nearsightedness or farsightedness– Thin cornea, corneal scarring

• Reversible• Requires a laser procedure before surgery• May develop a cataract or elevated pressure in the eye

Intacs

• Intracorneal ring segments• Plastic rings that are placed into

the cornea to reshape the curvature of the cornea.

• Only approved for patients with a low degree of nearsightedness and in patients with keratoconus.

• Reversible• Side effects: cornea scarring,

glare/halos, inflammation, infection

Options for refractive correction

• Correction for distance vision• Correction for near vision• Monovision

Medical Corneal Procedures

Penetrating Keratoplasty

Penetrating Keratoplasty

• Full thickness corneal transplant• Treatment for patients that have disease in

multiple or all layers of the cornea• Sutures are needed to hold the graft in

position

Penetrating Keratoplasty• Requires post-op steroid drops for life to

prevent graft rejection• Postoperative astigmatism (irregular

shape of the cornea)• Suture problems

Pre op Post op

Deep Anterior Lamellar Keratoplasty

Deep Anterior Lamellar Keratoplasty

• Abbreviated DALK• Partial thickness corneal transplant of the

upper layers of the cornea (epithelium, bowman’s, and stroma)

• This surgery is used for patients with keratoconus or a corneal scar

• This surgery requires normal endothelium

DALK• Because only the top part of the cornea is transplanted, the risk

of rejection is lower. • Better structural integrity• Risk of haze in between the graft and the host cornea• Similar suture issues/complications as with a full thickness

corneal transplant.• Risk of intra-operative break of the remaining corneal tissue that

would require a conversion to a full thickness corneal transplant.Pre op Post op

Descemet’s Stripping Endothelial Keratoplasty

Descemet’s Stripping Endothelial Keratoplasty

• Abbreviated DSEK, DSAEK (automated)• Partial thickness corneal transplant of the inner

layers of the cornea (descemet’s and endo).• This surgery is used for patients with Fuchs’

corneal dystrophy or Pseudophakic bullous keratopathy.

• No sutures used on the graft• An air bubble is used to hold the tissue in place for

the first few days.• Maintains the structural integrity of the eye.

DSEK• Required constant face up positioning for 2-3

days after surgery (except meals and bathroom). The head up positioning allows the bubble to hold the graft in position until the graft attaches.

• Risk of graft dislocation, haze/scar formation between the graft and the host cornea.

DSEK• Faster visual recovery than PK• Less astigmatism (irregular shape of the cornea)• Long term post-op steroid drops are needed prevent

rejection

Pre op Post op

DSEK can be used if a patient has a failed PK

• The new DSEK graft can be placed under the old PK (full thickness graft). – Offers a faster visual recovery– No sutures

Pre-op Post-op

Descemet’s Membrane Endothelial Keratoplasty

Descemet’s Membrane Endothelial Keratoplasty

• Abbreviated DMEK• Partial thickness corneal transplant of the inner

layers of the cornea (descemet’s and endo, no stroma tissue)

• This surgery is used for patients with Fuchs’ corneal dystrophy or Pseudophakic bullous keratopathy

• No sutures used on the graft• An air bubble is used to hold the tissue in place for

the first few days• Maintains the structural integrity of the eye.

Descemet’s Membrane Endothelial Keratoplasty

• Limitations-– Difficult to obtain the tissue– Difficult to insert tissue because it is so thin

• May decrease the number of endothelial cells

– Higher rebubble rate

• Potential Benefits-– Smaller incision– Better visual result– Less graft rejection

Boston Keratoprosthesis (artificial cornea)

• Type 1 • Type 2

Boston Keratoprosthesis type 1

Boston Keratoprosthesis type 1• Abbreviated- K- Pro, Boston K-Pro• Artificial cornea made of plastic and titanium• Requires sutures around the graft

Boston Keratoprosthesis type 1• This surgery is reserved for patients with

extensive scarring or multiple failed grafts with a potential to have good vision.

• Because of the prosthesis, patients will need to wear a contact lens and use drops to prevent an infection.

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