Visually significant lens opacity
Rarely, a cataract causing intraocular inflammation and/or glaucoma
Anesthesia: topical or local
Extracapsular method: An incision is made near the limbus, an anterior capsulotomy is performed, the lens nucleus is prolapsed out of the eye, the residual cortical material is removed, an IOL is placed, and the wound is usually sutured.
Phacoemulsification method: A small limbal or clear corneal incision is made, an anterior capsulotomy is performed, the lens nucleus is fragmented and removed with an ultrasound probe, the residual cortical material is removed, and an IOL is placed. Often, no sutures are required.
Postoperative management: topical corticosteroid and antibiotics, often a NSAID
Lens material falls into posterior segment
Phacoemulsification wound burn (Fig. 10-1A)
Wound leak, wound infection
Cystoid macular edema
Traumatic wound rupture
Temporary or permanent corneal edema
Excellent. PCO may require a laser capsulotomy.
FULL-THICKNESS CORNEAL TRANSPLANTATION (PENETRATING KERATOPLASTY)
Penetrating keratoplasty involves removal of diseased host tissue and replacing it with full-thickness normal donor cornea. It is one of the most successful transplant operations today, depending on the primary corneal disease.
Optical: to improve vision
Tectonic: to restore the structural integrity of the eye
Therapeutic: usually performed to remove infected and/or perforated corneal tissue that is not responsive to medical treatment
Pain: to improve pain from chronic bullous keratopathy
Cosmetic: to restore a more normal appearance to the eye
Most common indications for penetrating keratoplasty are regrafts, keratoconus, aphakic or pseudophakic bullous keratopathy, Fuchs dystrophy and other corneal dystrophies, and infectious and traumatic corneal scarring.
Donor Tissue Contraindications
Death of unknown cause
Death from central nervous system diseases of unknown etiology
Central nervous system infections (e.g., Creutzfeldt-Jakob disease, subacute sclerosing panencephalitis, progressive multifocal leukoencephalopathy)
Systemic infections (e.g., AIDS, viral hepatitis, rabies, septicemia, cytomegalovirus infection)
Lymphoma and leukemia
Unfavorable Prognostic Factors
Severe stromal vascularization
Previous graft rejection
Decreased corneal sensation (e.g., herpes keratitis)
Significant anterior synechiae
Active corneal or intraocular infection
Severe dry eyes
Ocular surface inflammation, cicatrization, and keratinization
Significant limbal stem cell deficiency
Extreme thinning or irregularity at the intended graft–host junction
Eyelid disorders: ectropion, entropion, exposure
Anesthesia: local or general anesthesia
Preparation of operative eye: often, placement of a Flieringa ring helps to stabilize the globe.
Determination of graft size: Routine graft sizes vary from 7.25 to 8.5 mm.
Trephination of donor cornea: typically performed using a posterior endothelial punch method, but can also be performed with a femtosecond laser. The trephine is usually 0.25 to 0.5 mm larger than that for host cornea trephination.
Excision of host cornea: Trephination of host cornea can be done by using a manual trephine (e.g., Weck trephine), a vacuum trephine (e.g., Barron-Hessburg or Hanna trephine), or a femtosecond laser. A partial-thickness trephination is first carried out, the anterior chamber is then entered using a blade, and finally excision is completed using corneal scissors.
Postoperative management: topical corticosteroid and antibiotics.
Where indicated, penetrating keratoplasty can be combined with any of the following procedures:
Cataract extraction with intraocular lens implantation (triple procedure)
Anterior vitrectomy with intraocular lens implantation
Intraocular lens exchange, either anterior chamber lens or scleral or iris fixated posterior chamber lens
Glaucoma drainage devices or trabeculectomy
Pars plana vitrectomy, often with a temporary keratoprosthesis
Eccentric, tilted, or irregular trephination of host or donor cornea
Damage to iris or lens
► Endophthalmitis (Fig. 10-2D)
► Retinal detachment
► Cystoid macular edema
► Primary failure: endothelial damage during surgery, poor-quality donor tissue (Fig. 10-2E)
► Wound leak (Fig. 10-2F)
► Persistent epithelial defect (Fig. 10-2G)
► Flat anterior chamber (typically from a wound leak or angle-closure glaucoma)
► Infectious keratitis, suture abscess (Fig. 10-2H)
► Recurrence of disease: dystrophies, infection
► Epithelial downgrowth and retrocorneal fibrous membrane (Fig. 10-2I)
► Vitreous touch
► Iris prolapse
► Wound dehiscence
► Traumatic wound rupture (Fig. 10-2L)
► Irregular astigmatism
Poor to excellent, depending on the indication for surgery.
Endothelial keratoplasty involves removal of diseased Descemet’s membrane and endothelium (most commonly) and replacement with healthy Descemet’s and endothelium (Descemet’s membrane endothelial keratoplasty [DMEK]), usually with some posterior stroma (Descemet’s stripping endothelial keratoplasty [DSEK]).
No corneal sutures
Less change in corneal curvature
Not an open-sky procedure
Technically more challenging; more difficult to perform other intraocular surgeries
Potentially more traumatic to the donor endothelium
Most Common Indications
Pseudophakic bullous keratopathy
Anesthesia: topical, local, or general anesthesia
Determination of graft size: Routine graft sizes vary from 7.5 to 8.5 mm.
Preparation of donor cornea: DSEK graft is typically fashioned with a microkeratome but can be fashioned with a femtosecond laser using an artificial anterior chamber or manually using a whole globe. DMEK tissue is generated manually.
Removal of host Descemet’s and endothelium: Through a small scleral, limbal, or clear corneal incision, Descemet’s membrane is scored, stripped, and removed from the eye.
Insertion of the donor cornea: Numerous insertion methods, including folding and using a variety of inserters, are used to place the donor cornea in the eye. An air bubble is used to push and hold the donor cornea up against the posterior stroma. The wound may be sutured closed; 10-0 nylon is usually used.
Postoperative management: topical corticosteroid and antibiotics
As in penetrating keratoplasty, endothelial keratoplasty can be combined with other intraocular surgeries.
Donor graft folds or decentration (Fig. 10-3F)
Others similar to penetrating keratoplasty, although there is less chance of expulsive hemorrhage, wound leaks, wound dehiscence, persistent epithelial defects, suture-related problems and irregular astigmatism
Good to excellent, depending on the indication for surgery
ANTERIOR LAMELLAR KERATOPLASTY
Anterior lamellar keratoplasty involves removal of the anterior cornea and replacing it with partial-thickness normal donor cornea.
Donor endothelial cell density is not important.
The anterior chamber is not entered, so complications such as expulsive hemorrhage and endophthalmitis are avoided.
There is no risk of endothelial rejection.
Technical complexity of the procedure
Opacification of the lamellar interface, which may reduce visual acuity
Anterior corneal scars and dystrophies
Peripheral ulcerative keratitis
Terrien’s marginal degeneration
Rarely, infectious keratitis, superficial corneal tumors
Local or general anesthesia
Partial-thickness corneal trephination (encompassing the pathology) is performed on the recipient cornea with a blade or a femtosecond laser.
Lamellar dissection is then carried out on the recipient cornea using a blunt dissecting blade or a femtosecond laser. Alternatively, Descemet’s membrane can be separated from the posterior stroma (e.g., with air as in the Anwar big bubble technique or with viscoelastic), which is termed deep anterior lamellar keratoplasty (DALK).
Donor lamellar cornea is dissected and trephined with a blade or femtosecond laser. It is usually 0.25 to 0.5 mm larger than the recipient bed. Either a whole eye or a corneoscleral button fixated in an artificial chamber can be used. In DALK, a full-thickness corneal button, usually denuded of its Descemet’s membrane, is used.
Alternatively, an automated microkeratome can be used to dissect both the donor and recipient cornea.
The recipient bed is irrigated to remove epithelium, debris, and blood, and the donor cornea is sutured with 10-0 nylon using either interrupted or running sutures (Fig. 10-4A and B) or, occasionally, fibrin glue.
Postoperative management: topical corticosteroid and antibiotics
Perforation of recipient or donor cornea during dissection, with possible need to convert to a penetrating keratoplasty
Double anterior chamber (Fig. 10-4C)
Opacification of lamellar interface
Recurrence of disease: dystrophies, infection
Persistent epithelial defect
Fibrovascular ingrowth into lamellar interface
Stromal rejection (rare)
Poor to excellent, depending on the indication for surgery