Corneal Conundrums

Educational Objectives

The goal of this program is to improve the management of corneal complications associated with cataract surgery. Af­ter hearing and assimilating this program, the participant will be better able to:

1.   Select appropriate treatment of zonular weakness, based on the type and severity of the condition.

2.   Choose the best intraocular lens and suturing approach for patients with poor capsular support.

3.   Recognize the risk factors for and treat corneal complications of cataract surgery.

4.   Prevent and treat thermal burns associated with phacoemulsification.

5.   Summarize the advantages and disadvantages of combined vs staged surgical procedures for corneal transplan­tation and cataract surgery.

Faculty Disclosure

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the planning committee to disclose relevant financial relationships within the past 12 months that might create any personal conflicts of in­terest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, Dr. Kim reported serving as a consultant for Alcon, Allergan, Becton, Dickinson, and Company, Inspire, ISTA, Pfizer, and Powervision. Dr. Trocme and the planning committee reported nothing to disclose. In his lecture, Dr. Kim presents information related to off-label or investigational use of a therapy, product, or device

Acknowledgements

Lectures by Dr. Kim were recorded at 8th Annual Downeast Ophthalmology Symposium, held October 2-4, 2009, in Bar Harbor, ME, and presented by the Maine Society of Eye Physicians and Surgeons. Dr. Trocme presented at Update for the Comprehensive Ophthalmologist 2009, held April 24, 2009, in Cleveland, OH, and presented by the University Hospitals, Case Medical Center, Case Western Reserve University School of Medicine. The Audio-Digest Foundation thanks the speakers and the sponsors for their cooperation in the production of this program.

IOL Selection and Fixation Without Zonular and Capsular Support

Terry Kim, MD, Associate Professor, Department of Ophthalmology, Duke University Eye Center, Durham, NC

Zonular weakness: stationary form (caused by trauma or iatrogenic process); progressive form (congenital or with pseudoexfoliation [PXF]; grading scale  —  minimal (no overt dialysis and minimal phacodonesis); mild (<4 clock hours dialysis with mild phacodonesis; possible ovalization of capsulorrhexis); moderate and severe (extensive phacodonesis, overt decentration, and capsular collapse); testing  —  look for residual shaking after patient gazes right or left then focuses straight; treatment  —  capsular tension ring (CTR) for mild cases; sutured capsular tension segment (CTS), modified Cionni ring, or anterior chamber (AC) intraocular lens (IOL) for more severe cases

Types of capsular tension rings: Cionni modified CTR (M-CTR) has eyelet to suture to sclera for severe phacodo­nesis; CTS placed around equator of zonule and sutured for more support; CTRs available in different sizes de­termined by axial length

Implantation: with injector (eg, OPHTEC), move cortex, load ring, and dial it toward area of zonular weakness; can use second instrument (eg, Sinskey hook) to support CTR and avoid exerting stress; fish-tail technique  —  bend Morcher ring so loop goes in first, hold eyelets, then insert distal part of ring under capsule and into bag one ring at a time; minimizes stress on capsule without focusing on location of zonular dehiscence; spring constants for CTRs differ, and some rings may break; requires 4-mm incision; timing  —speaker prefers to implant later; all CTRs contraindicated in presence of anterior or posterior capsular tear

Limitations: intact capsular bag and capsulorrhexis required, except with CTS; standard CTRs do not recenter se­verely subluxed capsular bags (do not use if zonular dehiscence ³6-12 hr); do not prevent progressive zonule loss; if implanted in patient with PXF, lens may subluxate 5 to 10 yr later

IOL options after CTR: speaker prefers single-piece acrylic lenses (unfold slowly and have ability to center)

Sulcus IOL: consider if anterior capsular support ³9 clock hours; good capsulorrhexis critical; if capsular bag bro­ken, possible to place lens in sulcus and capture optic within bag; necessary to size and center capsulorrhexis ap­propriately to fixate premium IOLs, even if bag intact; sulcus IOL appropriate for cases with capsular tear if support ³9 clock hours; speaker reduces IOL power by 0.5 diopter unless capturing optic in capsular bag; prefers 3-piece acrylic IOL; speaker cautions against use of single-piece IOLs in sulcus to avoid chafing of iris, disper­sion of pigment, chronic uveitis, and cystoid macular edema (CME); rotate lens so haptics 90° from AC defect

AC lenses: appropriate for patients with no capsular or zonular support (eg, ³60 yr of age); flexible open-loop types with 4-point fixation work well; 6-mm incision and peripheral iridectomy needed to prevent pupillary block, un­less eye vitrectomized; speaker measures horizontally (white-to-white) and adds 1 mm

Iris claw lenses: eg, Artisan-Verisys lens; approved in United States for treatment of myopia, but use for aphakic patients available only in Europe; technique requires enclavating iris into lens by clipping into eyelets

Iris-fixated lens: if iris viable, implant posterior chamber (PC) IOL and fixate to iris using McCannell technique ; fold 3-piece foldable lens through 4-mm or 4.1-mm incision; unfold with optic captured by iris and haptics pos­terior to iris; can suture to iris through 2 paracentesis incisions as peripherally and involving as little of the iris as possible; technique allows use of small incisions

Scleral fixated lens: appropriate for abnormal iris (eg, traumatic mydriasis or aniridia); mark 180° apart on sclera (whether performing scleral flap or cutdown) to avoid decentering lens; use 2-point fixation; speaker prefers Al­con CZ 70 BD lens (has eyelets for sutures); requires larger incision (eg, 7-mm incision for CZ 70 BD; speaker makes incision through scleral tunnel); often requires additional mechanical vitrectomy; correct suture placement necessary to avoid lens tilt (especially in aniridic patients); associated risks for prolene suture exposure and vitre­ous hemorrhage

Ab interno technique: use CIF-4 needle on 9-0 or 10-0 prolene through scleral stab incision;

Ab externo technique: push STC-6 needle with 9-0 or 10-0 prolene into eye; use 30-gauge needle on opposite side and feed needle into syringe handle; perform twice, then pull both prolene sutures out and fixate to lens under scleral flap or scleral cutdown (speaker prefers latter)

Advantages: allows fixation of lens in absence of capsular or zonular support; appropriate for patients with lower endothelial cell count or angle abnormality

Literature review: open-loop AC IOLs, scleral-sutured, and iris-sutured PC IOLs found to have comparable safety and efficacy in correcting aphakia in eyes without capsular support  

Zonular instability guidelines: if patient has 0 to 2 clock hours instability (0 defined as movement of capsular bag during cortical removal and aspiration of viscoelastic without frank dehiscence), use 3-piece lens and place haptics in quadrant of dialysis; alternatively, use CTR after cautious phacoemulsification (PE); place CTR in eyes with <4 clock hours zonular dehiscence, mild phacodonesis, and ovalization of capsulorrhexis (may need iris or anterior capsule retractor); in eyes with 4 to 8 clock hours of dehiscence (speaker limits to £6 clock hours), fixate modified CTR or CTS to sclera (iris or capsule retractor required); if >8 clock hours dehiscence, retina specialist should per­form pars plana vitrectomy and lensectomy; AC IOL or iris-fixated PC IOL can then be implanted

Corneal Complications of Cataract Surgery

Dr. Kim

Epithelial defects: prescreen for anterior basement membrane dystrophy (more common in elderly patients); con­sider bandage contact lens or collagen shield; risk for infectious keratitis relatively low; avascularity may increase risk; obtain culture and possibly biopsy; treat with topical and systemic fortified antibiotics; severe cases may need corneal transplant, conjunctival flap, or lamellar keratoplasty

Corneal melt: risk factors  —  severe dry eye, persistent epithelial defects, neurotrophic keratopathy, severe ocular surface disease (eg, ocular cicatricial pemphigoid, Stevens-Johnson syndrome, graft vs host disease, chemical burns), collagen vascular disease, and inappropriately dosed topical nonsteroidal anti-inflammatory drugs (NSAIDs); treatment  —  lubricants, collagenase inhibitors (eg, topical 2% medroxyprogesterone [Provera], oral doxycycline), cycloplegia, punctual occlusion; systemic steroids or immunosuppressants for underlying collagen vascular disease; graft procedure required for severe cases

Wound healing: strength of wound 10% after 1 wk, 40% after 2 mo, and 80% after 2 yr; treatment of leakage  —  continue topical antibiotics, discontinue steroids, start cycloplegia and aqueous suppressants, use bandage contact lens or collagen shield for clear corneal incisions, and resuture for severe cases; treatment of wound dehiscence with iris prolapse  —reposition iris if prolapse <24 hr; if necrotic or other debris present, scrape or excise and repo­sition rest of iris to avoid infection or epithelial ingrowth; inadvertent filtering bleb may occur; decide on reposi­tioning, exchanging, or removing IOL, and whether vitrectomy required

Thermal burns: due to inadequate irrigation or excessive aspiration of fluid during PE; caused by kinking of irriga­tion tubing or loose connections, tight incisions, or heavy use of viscoelastic

Case example: speaker used trypan blue under viscoelastic and added air bubble under iris; during horizontal chop, noticed leathery posterior plate; reapplied viscoelastic »6 times and noticed irrigation tubing had fallen off PE handpiece; resulted in wound burn with corneal striae; wound continued to leak after suturing (similar to stellate corneal laceration); successfully closed with cyanoacrylate glue

Prevention: occurs within seconds; use pulsed ultrasound, cooled balanced salt solution (BSS), and aspiration bypass system; aspirate all viscoelastics, and check handpiece connections

Treatment: close wound and minimize astigmatism with suturing; may require lamellar or full-thickness patch graft

Corneal edema: if moderate to severe, inspect anterior segment for fragments of lens, cortex, or capsule, dislocated IOL, or detachment of Descemet; treat aggressively with 1% prednisolone every hour or 0.5% difluprednate (Du­rezol); may need corneal transplant; prevention  —  stain interior capsule under air bubble and under iris if pupil small; use chopper to minimize exposure to ultrasound; good rotation of nucleus important; needling mature cataracts  —  puncture bag with 25-gauge needle, aspirate liquefied cortex to prevent milky cortical flow and decom­press capsule to prevent “Argentinian flag sign”; or do slight PE of capsule before capsulorrhexis

Descemet membrane detachment: prognosis depends on extent of detachment (better with planar £1 mm than with nonplanar), not on duration (can reattach after 1-2 mo)

Diagnosis: examine posterior cornea with slit lamp for wavy line; ocular coherence tomography (OCT) and topical glycerin helpful

Treatment: speaker prefers intracameral gas injection performed with topical anesthesia and slit lamp; use 2 25-gauge needles, one on 3-mL syringe filled with 20% sulfur hexafluoride gas; enter AC simultaneously with 2 nee­dles parallel to plane of iris; as gas injected, aqueous egresses out other eye; pull out after AC filled »60% to 70%; use cycloplegia and place patient in supine position

Epithelial ingrowth: cystic or sheetlike; possible to aspirate cysts out of AC; sheets appear as grayish-white retrocor­neal membrane, clumped epithelial cells, or abnormal iris color or contour, and more difficult to treat; anecdotal re­ports of successful treatment with intracameral 5-fluoruracil

Fibrous ingrowth: higher incidence but less aggressive; observe or excise surgically; slow growing and self-limiting

Toxic anterior segment syndrome (TASS): sterile postoperative inflammatory reaction caused by noninfectious substance; starts 12 to 48 hr after cataract or anterior segment surgery; Gram stain and culture results negative; treat with steroids

Clinical presentation: decreased vision, pain, redness, diffuse corneal edema, hypopyon, and fixed dilated pupil; ini­tial shutdown of ciliary body, then increased pressure (glaucoma)

Differentiating from infectious endophthalmitis (IE): TASS occurs 12 to 48 hr after surgery, while IE develops af­ter 4 to 7 days; inflammation usually limited to anterior segment with TASS, but IE involves posterior segment; TASS shows severe edema, but less severe in IE; TASS responds to topical steroids, while IE requires intravitreal or systemic antibiotics; IE can be negative on culture or Gram stain; causes include irrigation fluid, contaminated ge­neric trypan blue, and errors during formulation of antibiotics for intracameral injection

Treatment: prednisolone or difluprednate; watch for glaucoma and cystoid macular edema (CME)

Outbreaks: cases occur in clusters or outbreaks (environmental and toxic control issue); requires analysis of all med­ications and fluids, operating room, and sterilizing protocols

Corneal Tranplantation and Cataract Surgery

Stefan D. Trocme, MD, Professor, Department of Ophthalmology and Visual Sciences, Case Western Reserve University; Director of Refractive Surgery Service and Director, Division of Ocular Surface Diseases and Sur­gery, University Hospitals Case Medical Center, Cleveland, OH

Combined Cataract Surgery and Penetrating
Keratoplasty (PKP)

Advantages: cataracts progress after PKP because of surgical trauma, corticosteroid use, and inflammation; studies show good results for combined PKP, extracapsular cataract extraction (ECCE), and implantation of IOL; survival of graft less certain when cataract surgery performed after PKP; especially useful in cases of opacified cornea with poor visualization of cataract, dense cataracts requiring extensive PE, presence of posterior synechiae (as open-sky extraction with triple procedure allows goniosynechiae lysis), or with patients in poor health

Disadvantages: difficulty calculating power of IOL; eye more vulnerable to vitreous loss or expulsive hemorrhage during open-sky approach

Surgical options: simultaneous ECCE and PKP (triple procedure); PE followed later by PKP; keratoprosthesis to perform PE followed by PKP (rarely used); keratoprosthesis requires extra time and limits size of graft

Open-sky ECCE: consider preplacing posterior sclerotomy 4 mm from limbus to provide entry point for possible posterior vitrectomy; choose type of capsulotomy or capsulorrhexis; capsulorrhexis too small for extraction of nu­cleus with triple procedure, requires relaxing incisions, and more prone to radialize (“can opener” capsulotomy therefore preferable); foldable IOLs not rigid enough to hold back vitreous, so polymethylmethacrylate lens recom­mended

Staged Procedures

Penetrating keratoplasty first and cataract extraction later

Advantages: keratotomy readings (Ks) available for determination of IOL power; modern PE approaches and fold­able IOLs used

Disadvantages: poor corneal clarity makes cataract surgery difficult; cornea may become cloudy during surgery

Descemet stripping and automated endothelial keratoplasty (DSAEK) triple procedure

Advantages: good for mild to moderately severe endothelial dystrophy and mild to moderate cataracts; IOL calcu­lations easier, and postoperative Ks change minimally; uses PE with small incision and foldable IOLs

Disadvantages: causes hyperopic shift of »1.5 diopters (1.0 to 3.0 diopter range); speaker recommends myopic end point in choice of IOL; if staged DSAEK performed first and cataract surgery later, thickness of graft may in­crease risk for endothelial injury

Suggested Reading

Alp MN et al: Ultrasound biomicroscopic evaluation of the efficacy of a transillumination technique for ciliary sulcus localiza­tion in transscleral fixation of posterior chamber intraocular lenses. J Cataract Refract Surg 35:291, 2009; Baykara M, Ucan G: Modifying the position of cataract incisions in triple procedure. Euro J Ophthalmol 18:891, 2008; Blecher MH, Kirk MR: Surgical strategies for the management of zonular compromise. Curr Opin Ophthalmol 19:31, 2009; Chang DF et al: Compli­cations of sulcus placement of single-piece acrylic intraocular lenses: recommendations for backup IOL implantation follow­ing posterior capsule rupture. J Cataract Refract Surg 35:1445, 2009; Chen SX et al: Modified cow-hitch suture fixation of transscleral sutured posterior chamber intraocular lenses: long-term safety and efficacy. J Cataract Refract Surg 34:452, 2008; Guell JL et al: A review of suturing techniques for posterior chamber lenses. Curr Opin Ophthalmol 15:44, 2004; Gupta SC, Sony P: Open-loop tip capsule support hooks for zonular dehiscence. J Cataract Refract Surg 33:928, 2007; Higashide T et al: Anterior segment optical coherence tomography findings of reverse pupillary block after scleral-fixated sutured posterior chamber intraocular lens implantation. J Cataract Refract Surg 35:1540, 2009; Holland SP et al: Update on toxic anterior seg­ment syndrome. Curr Opinion Ophthalmol 18:4, 2008; John T, Shah AA: New surgical technique: upside-down phacoemul­sification with posterior chamber intraocular lens and Descemet’s stripping automated endothelial keratoplasty (DSAEK). Ann Ophthalmol (Skokie) 41:16, 2009; Jun B et al: Refractive change after descemet stripping with automated endothelial kerato­plasty surgery and its correlation with graft thickness and diameter. Cornea 28:19, 2009; Koss MJ, Kohnen T: Intraocular ar­chitecture of secondary implanted anterior chamber iris-claw lenses in aphakic eyes evaluated with anterior segment optical coherence tomography. Br J Ophthalmol 93:1301, 2009; Mamalis N et al: Toxic anterior segment syndrome. J Cataract Re­fract Surg 32: 324, 2008; Nguyen DQ et al: The visual and refractive outcomes of combined and sequential penetrating kera­toplasty, cataract extraction, and intraocular lens insertion. Eye 23:1295, 2009; Schaal S, Barr CC: Management of retained lens fragments after cataract surgery with and without pars plana vitrectomy. J Cataract Refract Surg 35:863, 2009; Shih Cy et al: Visually significant and nonsignificant complications arising from Descemet stripping automated endothelial keratoplasty. Am J Ophthalmol Oct 1, 2009 [Epub ahead of print]; Shulman J et al: Failed Descemet-stripping automated endothelial kera­toplasty grafts: a clinicopathologic analysis. Am J Ophthalmol Aug 10, 2009 [Epub ahead of print]; Takimoto M et al: Effect of a capsular tension ring on prevention of intraocular lens decentration and tilt and on anterior capsule contraction after cata­ract surgery. Jpn J Ophthalmol 52:363, 2008.