Optimizing Outcomes in Cataract Surgery

From A Look at Eye Care: the 727th Meeting of the New England Ophthalmological Society

Educational Objectives

The goal of this program is to improve the outcomes of cataract surgery. After hearing and assimilating this program, the clinician will be better able to:

1.   Summarize the risk factors for the development of endophthalmitis after cataract surgery.

2.   Describe and implement strategies to prevent colonization of the ocular surface and entry of bacteria into the eye.

3.   Evaluate the roles of topical and intraocular antibiotics for the prevention of endophthalmitis and choose ap­propriate agents.

4.   Communicate realistic expectations for patients undergoing implantation of refractive intraocular lenses (IOLs) and manage postoperative problems.

5.   Compare and contrast the use of limbal relaxing incisions vs toric IOLs for managing astigmatism during 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, the following has been disclosed: Dr. O’Brien has served as an ad hoc nonsalaried advisor/consultant for Alcon, Allergan, Bausch and Lomb, Inspire, ISTA, and VISTA­KON. Dr. Pineda has served on the Speakers’ Bureaus of Alcon and Allergan and as a consultant for Alcon. Dr. Kieval and the planning committee reported nothing to disclose. In their lectures, Drs. Kieval and O’Brien present information related to the off-label or investigational use of a therapy, product, or device.

Acknowledgements

Lectures by Drs. O’Brien, Kieval, and Pineda were recorded at A Look at Eye Care: 727th Meeting of the New England Ophthalmological Society, held November 20, 2009, in Boston, MA, and presented by the New England Ophthalmological Society. The Audio-Digest Foundation thanks the speakers and the New England Ophthalmological Society for their coop­eration in the production of this program.

Antimicrobial Prophylaxis in Cataract Surgery: Mission Impossible?

Terrence P. O’Brien, MD, Professor of Ophthalmology, University of Miami, Miller School of Medicine, and Director of Refractive Surgery Service, Bascom Palmer Eye Institute, Miami, FL

Background: rates of endophthalmitis increasing, according to study of United States Medicare database; data from Bascom Palmer Institute show rate stationary over past 10 yr; more complicated procedures (eg, penetrating kerato­plasty) with potential for donor-to-host contamination have higher rates of infection; use of antimetabolites in glau­coma surgery also increases rate; pars plana vitrectomy has relatively low rate of infection; implantation of secondary intraocular lenses (IOLs) has higher risk

Risk factors for endophthalmitis: application of anesthetic gel preparations may block antiseptic and antibiotic; more complicated surgeries and vitreous findings during cataract surgery lead to higher rates; location of incisions, comorbid conditions, silicon IOLs, and nonuse of eye patch suggested as risk factors

Sources: transient hypotony during cataract surgery can cause inflow of extraocular fluid and introduce periocular flora; Endophthalmitis Vitrectomy Study (EVS) showed 94% of cases involved gram-positive organisms, espe­cially coagulase-negative staphylococci, and 6% involved gram-negative organisms; study found staphylococci ac­counted for »50% of cases; 7% had negative culture results; 2 cases caused by streptococci, and remainder by Enterococcus species and polymicrobial infections

Prevention Strategies

Ocular surface: antiseptics best approach to reducing colonization; apply 10% solution of povidone-iodine to skin and 5% solution to ocular surface (reduces rate of endophthalmitis by 75%-80%); antibiotics synergistic when combined with antiseptic (eg, 3-day course of advanced-generation fluoroquinolone plus povidone-iodine reduces culture positivity by 95%); drape to sequester cilia and meibomian glands from operative field

Intraocular introduction of pathogens: studies of uncomplicated advanced phacoemulsification with implantation of IOLs showed 5% to 40% recovery of organisms from aqueous humor; application of topical antibiotics effective before and after cataract surgery; newer agents provide greater activity against gram-positive organisms and remain longer within eye (eg, modified with 8-methoxy group, cyclopropyl group, and bulkier side chains)

Topical antibiotics: in vitro data show newer-generation fluoroquinolones have greater potency, compared to ofloxa­cin, ciprofloxacin, and levofloxacin; problems  —  resistance to fluoroquinolones increasing among organisms that cause endophthalmitis, keratitis, and external infections; vancomycin preferred agent for coagulase-negative staph­ylococci resistant to fluoroquinolones; Ocular Trust data show increased rate of recovery of methicillin-resistant staphylococci from ocular isolates; consider using alternative to fluoroquinolone; bioavailability  —agents must penetrate aqueous and vitreous humors for efficacy; therapeutic index or inhibitory quotient derived from concen­tration of drug in tissue and potency (minimal inhibitory concentration); study of advanced-generation fluoroquino­lones showed differences among agents in penetration into aqueous humor; topical application of antibiotics may prevent endophthalmitis, however retina literature shows concentrations achieved with topical dosing not likely to be high enough to protect against organisms in vitreous

Intraocular antibiotics: European study  —  found reduced rate of endophthalmitis with intracameral cefuroxime, but rate in control group 3-fold higher than typical, and cefuroxime-resistant gram-positive organisms caused endo­phthalmitis; cefuroxime not approved by Food and Drug Administration (FDA) for this use and not effective against organisms of concern; unlike fluoroquinolones (activity depends on concentration), cephalosporins have time-dependent bactericidal activity and take longer to kill; other issues include potential for cystoid macular edema (shown in study of vancomycin) and potential for toxic anterior segment syndrome (TASS)

Agents: available agents include glycopeptides (eg, vancomycin); cephalosporins, first- (eg, cefazolin) or advanced-generation (cefuroxime); and advanced-generation fluoroquinolones; all show comparable results, but have differ­ent mechanisms of action and gaps in spectrum (eg, vancomycin has narrow spectrum, cephalosporins miss many potential pathogens, fluoroquinolones effective against most organisms except severe strains of pseudomonas); anaphylaxis reported with subconjunctival use of cefazolin and intracameral cefuroxime; speaker prefers fluoroqui­nolones

Other recommendations: consider placing 10-0 suture in wound; avoid transient hypotony that occurs in 24% of cases; speaker considers use of intracameral antibiotic unproven

Management of Patient Dissatisfaction with
Refractive Intraocular Lenses

Dr. O’Brien

Before surgery: establish realistic expectations; assess patient’s goals for visual function and frequency and impor­tance of activities in various levels of illumination; astigmatism often causes dissatisfaction; establish rapport with patient; patients made aware of potential problem before surgery better able to handle problem when it occurs

After surgery: spend extra time with patients who have major postsurgical problem; nonverbal as well as verbal communication important; alert staff that this patient needs special treatment; after patient issues addressed, con­tact risk management group and document everything thoroughly; follow process of notification, evaluation and investigation, documentation, and resolution

Corrective measures: improve distance visual acuity; eliminate astigmatism; enhance near vision; address common patient concerns

Factors affecting satisfaction with presbyopic lenses: cylinder and refractive error, capsular opacities, corneal and ocular surface disease, cystoid macular edema, centration of IOL in pupil, supratentorial suitability of patient

Capsular opacification: even minimal opacities degrade quality of vision; capsulotomy makes exchange of IOL more difficult

Crystalens: patients may not understand that migration and proliferation of epithelial cells may lead to changed func­tion; complications include vault syndrome, Z syndrome, and rupture of capsular bag

Corneal and ocular surface disease: cornea responsible for 66% of power of any lens; examine ocular surface, espe­cially for tear dysfunctional states, and treat disorders before surgery (eg, tear film break-up time and epithelial basement membrane dystrophy); possible to treat early capsular opacity by ocular surface optimization using mul­tifaceted approach that helps restore stability of tear film, allows cellular repair, and provides greater protection during interblink interval

Optical coherence tomography (OCT): use to identify abnormalities of vitreomacular interface before surgery

Centration of IOL on pupil: ensure optic centered during surgery; after surgery, use of argon laser iridoplasty to add 4 spots on mid periphery can center pupil in selected patients

Cylinder and refractive error: important to correct residual error; speaker prefers laser correction over relaxing in­cisions, piggybacking lenses, or exchanging IOL; use of advanced surface ablation vs femtosecond laser under de­bate; design of lenses may increase difficulty obtaining WaveScan analysis; lens introduces negative spherical aberration which should not be eliminated (would remove multifocality); WaveScan should agree with manifest re­fraction; treat astigmatism maximally

Procedures: advanced variable spot scanning with custom view platform has narrower field than conventional ap­proach; use cosine compensation to achieve more prolate ablation in patients undergoing conventional procedure; surface approach preferred in older patients because of small amount of residual ametropia; creating laser in situ keratomileusis (lasik) flap introduces aberrations; patients prone to dry eye or delayed healing benefit from ad­vanced surface ablation; speaker uses epithelial separator device to peel epithelial layer, carries out surface ablation centering over entrance pupil, removes residual myopia and astigmatism, uses mitomycin C with hydroreflotation method (ie, jet stream of balanced salt solution [BSS] used to replace epithelial sheet), applies drop of prednisolone acetate suspension to highlight epithelial layer, and places therapeutic bandage soft contact lens for 3 to 5 days

Excimer laser enhancements with refractive IOLs: remove any sutures, wait for refractive stability (8-12 wk), per­form neodymium:yttrium aluminum garnet (Nd:YAG) capsulotomy before excimer laser on all patients with ac­commodating lenses; try argon laser iridoplasty for patients with poorly centered multifocal IOLs; custom treatments possible with multifocal and accommodating IOLs, but avoid removing negative spherical aberration; optimize ocular surface before performing any of above procedures

Update on Endophthalmitis after Cataract Surgery

Jeremy Z. Kieval, MD, Lexington Eye Associates, Cornea and Refractive Surgery, Lexington, MA

Background: EVS found hypopyon present in only 25% of patients with endophthalmitis; incidence ranges from 0.02% to 0.36%; studies conflicting as to whether clear corneal incisions (CCIs) increase incidence, compared to scleral tunnel surgery

Risk factors: high bacterial load; blepharitis or conjunctivitis; diabetes or impaired immune function; complicated cataract surgery with vitreous loss or capsular rupture; silicon IOLs and CCIs (or unsutured CCIs)  

Prevention: >80% of causative bacteria genetically identical to patient’s periocular flora; contamination of anterior chamber occurs in >40% of uncomplicated cataract surgeries

Wound construction: CCI more likely to allow gaping of wound when intraocular pressure (IOP) <10 mm Hg; 20% of patients undergoing cataract surgery have IOP <5 mm Hg 30 min after CCI; architecture  —  square incisions more resistant to deformity than rectangular ones; location  —  86% of cases occurred in right eye, with incisions lo­cated inferotemporally; right-handed surgeons should sit in more superotemporal position; integrity  —  leakage of wound on first day after surgery increases risk 44-fold; avoid smaller incisions susceptible to torque during surgery; avoid “corneal tongue”; use stromal hydration to increase corneal thickness and force roof of incision onto floor to facilitate endothelial pumping; place suture if wound not secured

Increasing incidence of endophthalmitis: possibly due to use of CCIs or topical anesthesia; topical anesthesia does not provide akinesia of globe or eyelid and could introduce factors that change IOP and cause ingress of bacteria

Management of Astigmatism During
Cataract Surgery: Limbal Relaxing Incisions vs 
Toric Intraocular Lenses

Roberto Pineda, MD, Assistant Professor of Ophthalmology, Harvard Medical School, and Director of Refrac­tive Surgery, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston, MA

Surgical options

Low levels of astigmatism: perform on-axis or “mini” limbal relaxing incisions (LRIs), especially for presbyopic IOLs

Medium levels (1 to 1.25 D): use toric IOLs or LRIs

Medium-high levels (1.25 to 2.5 D): use toric IOLs

High levels (>2.5 D): use combination of toric IOLs, LRIs, or laser correction

On-axis cataract incisions: placed on steep axis to reduce pre-existing astigmatism; relevant for larger incisions, but easy to perform through LRI; relatively safe, no extra instrumentation required; achieve 0.25 to 0.50 D of correc­tion for 2.5-mm to 3.0-mm incisions

Limbal relaxing incisions: advantages  —  astigmatism corrected in cornea; inexpensive and easy; incisions do not rotate; performed at time of surgery; repeatable; no impact on healing (evaluate topography first to reduce risk for perforation); disadvantages  —lower precision than laser correction and toric IOLs; irritation; good for correction £1.5 D; combine with toric IOL for greater correction; good for nonorthogonal astigmatism (axis not in same meridian) or if capsular tear or zonular dialysis prevents placement of toric IOL; depth and location  —  aim for 10 to 11 mm; pachymetry not needed; LRIs heal faster than more central corneal incisions; quicker refractive stabilization, and less glare and for­eign body sensation than with astigmatic keratotomy (AK); no need to adjust to IOL power (no change in spherical equivalent; coupling ratio 1 to 1); procedure  —  identify and mark steep axis; blade depth usually »500 to 600 µm; augment effect of on-axis astigmatism by making incision through LRI; use LRI calculator; verify IOL and axis in operating room; complications  —  if incision on wrong axis, suture or place different incision; wound gapes more common with steel blades, if incision not perpendicular, or wound excessively manipulated; undercorrection if in­cision not deep enough; micro or macro perforations (suture if necessary)

Toric IOLs: correct from 1.0 to 2.25 D; more accurate, but correct astigmatism inside eye instead of on cornea; per­form with standard cataract surgery; contraindications include zonular dehiscence, pseudoexfoliation, weakened zonules, disruption of capsule, and previous intraocular surgery

Evaluating patients: before surgical correction of astigmatism, rule out abnormalities and evaluate corneal topogra­phy; after removing contact lenses, wait »1 mo for keratometry; avoid patients with degeneration (eg, keratoconus) and anterior basement membrane dystrophy (8%-12% of population)

New technologies: WaveTec Vision’s ORange machine provides intraoperative aberrometry

Suggested Reading

Amesbury EC, Miller KM: Correction of astigmatism at the time of cataract surgery. Curr Opin Ophthalmol 20:19, 2009; Choi JA, Chung SK: Safety of intracameral injection of gatifloxacin, levofloxacin on corneal endothelial structure and vi­ability. J Ocul Pharmacol Ther 25:425, 2009; Cornut PL et al: Bacterial contamination rate of the anterior chamber during cataract surgery using conventional culture and eubacterial PCR. Eur J Ophthalmol Dec 3, 2009 [Epub ahead of print]; Fine IH et al: Profile of clear corneal cataract incisions demonstrated by ocular coherence tomography. J Cataract Refract Surg 33:197, 2007; Gribomont AC: Post-cataract surgery endophthalmitis: an update. Bull Soc Belge Ophthalmol 311:43, 2009; Gualdi L et al: The use of NIDEK OPD Scan II wave front aberrometry in toric intraocular lens implantation. J Refract Surg 25(1 Suppl):S104, 2009; Keating GM: Levofloxacin 0.5% ophthalmic solution: a review of its use in the treatment of external ocular infections and in intraocular surgery. Drugs 69:1267, 2009; Lane SS et al: Comparison of clinical and pa­tient-reported outcomes with bilateral AcrySof toric or spherical control intraocular lenses. J Refract Surg 25:899, 2009; Macsai MS, Fontes BM: Refractive enhancement following presbyopia-correcting intraocular lens implantation. Curr Opin Ophthalmol 19:18, 2008; Maeda N: Clinical applications of wave front aberrometry – a review. Clin Experiment Ophthalmol 37:118, 2009; Major JC Jr et al: Staphylococcus aureus endophthalmitis: antibiotic susceptibilities, methicil­lin resistance, and clinical outcomes. Am J Ophthalmol Nov 17, 2009 [Epub ahead of print]; Mendicute J et al: Toric intra­ocular lens versus opposite clear corneal incisions to correct astigmatism in eyes having cataract surgery. J Cataract Refract Surg 35:451, 2009; Ouchi M, Kinoshita S: Prospective randomized trial of limbal relaxing incisions combined with micro­incision cataract surgery. J Refract Surg Oct 26, 2009 [Epub ahead of print]; Scoper SV: Review of third- and fourth-gener­ation fluoroquinolones in ophthalmology: in vitro and in vivo efficacy. Adv Ther 25:979, 2009; Velpandian T: Intraocular penetration of antimicrobial agents in ophthalmic infections and drug delivery strategies. Expert Opin Drug Deliv 6:255, 2009.