Surgery and Complications
CATARACT EXTRACTION AND INTRAOCULAR LENS IMPLANTATION
Cataract extraction and intraocular lens (IOL) implantation involve removal of a cloudy crystalline lens and replacement with an artificial lens. It is one of the most commonly performed surgical procedures.
• Visually significant lens opacity
• Rarely, a cataract causing intraocular inflammation and/or glaucoma (eFig. 10-1A1)
• 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. More recently, femtosecond laser technology has been used to perform certain aspects of cataract surgery, such as creating the anterior capsulotomy and softening the lens making removal less traumatic to the eye, and performing astigmatic keratotomy (AK) incisions with potential benefits over standard phacoemulsification surgery.
• Postoperative management: topical corticosteroid and antibiotics, often a nonsteroidal anti-inflammatory drug (NSAID)
▪ Expulsive hemorrhage
▪ Vitreous prolapse
▪ Lens material falls into posterior segment
▪ Phacoemulsification wound burn (Fig. 10-1A)
▪ Endophthalmitis (eFig. 10-1A2 and 3)
▪ Wound leak, wound infection
▪ Cystoid macular edema
▪ Retinal detachment
▪ Traumatic wound rupture (eFig. 10-1D4)
▪ Temporary or permanent corneal edema
▪ Posterior capsular opacity (PCO), very common (Fig. 10-1E and F)
• Excellent. PCO may require a laser capsulotomy.
FULL-THICKNESS CORNEAL TRANSPLANTATION (PENETRATING KERATOPLASTY)
Penetrating keratoplasty (PK) 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 PK are regrafts, keratoconus, aphakic or pseudophakic bullous keratopathy with scarring, Fuchs dystrophy with scarring, other corneal dystrophies, infectious and traumatic corneal scarring, and corneal ulceration or perforation.
Donor Tissue Contraindications
• Death from 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)
• Reye syndrome
• Lymphoma and leukemia
Unfavorable Prognostic Factors
• Severe stromal vascularization
• Previous graft rejection
• Decreased corneal sensation (e.g., herpes keratitis)
• Pediatric patients
• Active uveitis
• Significant anterior synechiae
• Uncontrolled glaucoma
• 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.
• Wound closure: Various suture methods, including interrupted, running, double running, or a combination, may be used. 10-0 nylon is usually used (Fig. 10-2A-C).
• Postoperative management: topical corticosteroids and antibiotics
• Where indicated, PK can be combined with any of the following procedures:
▪ Cataract extraction with IOL implantation (PK triple procedure)
▪ Anterior vitrectomy with IOL implantation
▪ IOL 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
▪ Expulsive hemorrhage
▪ Vitreous prolapse
▪ Sight threatening
▶ Endophthalmitis (Fig. 10-2D)
▶ Retinal detachment
▶ Cystoid macular edema
▪ Graft threatening
▶ Primary failure: endothelial damage during surgery, poor-quality donor tissue (Fig. 10-2E)
▶ Wound leak (Fig. 10-2F)
▶ Flat anterior chamber (typically from a wound leak or angle-closure glaucoma)
▶ Recurrence of disease: dystrophies, infection
▶ Vitreous touch
▶ Iris prolapse
▶ Wound dehiscence
▶ Irregular astigmatism
▶ Late wound ectasia (eFig. 10-2M1 and 2)
• Poor to excellent, depending on the indication for surgery
Endothelial keratoplasty (EK) involves removal of diseased Descemet membrane and endothelium (most commonly) and replacement with healthy Descemet and endothelium alone (Descemet membrane endothelial keratoplasty [DMEK]), or with some posterior stroma (Descemet stripping endothelial keratoplasty [DSEK]).
Advantages over a PK
• More rapid visual recovery (Fig. 10-3A-E)
• Stronger wound
• No corneal sutures
• Less change in corneal curvature
• Not an open-sky procedure
• Lower risk of rejection
Disadvantages Compared to a PK
• Technically more challenging; more difficult to perform other intraocular surgeries
• Potentially more traumatic to the donor endothelium
• Possibly higher risk of postoperative infection in the lamellar interface
Most Common Indications
• Fuchs dystrophy
• 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 and endothelium: Through a small scleral, limbal, or clear corneal incision, Descemet 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. A nonexpansile gas (e.g., 18% sulfur hexafluoride) may be used for DMEK. The wound may be sutured closed; 10-0 nylon is usually used.
• Postoperative management: topical corticosteroid and antibiotics. Patients are instructed to lay supine as much as possible for 1 to 5 days, less for DSEK, more for DMEK.
• As in PK, EK can be combined with other intraocular surgeries.
• Donor graft dislocation requiring rebubbling or repeat surgery (Fig. 10-3G and H, eFig. 10-3G and H)
• Reticular interface haze, often from retained viscoelastic, which usually improves over months (Fig. 10-3I, eFig. 10-3I1 and 2)
• Epithelial basement membrane (EBM) abnormalities can become more apparent after the preoperative corneal edema resolves. These irregularities may need to be treated with epithelial debridement with or without diamond burr polishing or excimer laser phototherapeutic keratectomy to achieve the best vision (eFig. 10-3J1 and 2).
• Rarely, IOLs (especially hydrophilic acrylic lenses) can develop opacities after EK, presumably from the air or gas tamponade (eFig. 10-3K).
• There are others similar to PK, although there is less chance of expulsive hemorrhage, wound leaks, wound dehiscence, persistent epithelial defects, suture-related problems, graft rejection, and irregular astigmatism (eFig. 10-3L).
• Good to excellent, depending on the indication for surgery