Cataract and Refractive Surgery

From the Cataract and Refractive Surgery Congress, presented by the Bascom Palmer Eye Institute, University of Miami Miller School of Medicine

Educational Objectives

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

1.   Control inflammation and uveitis before performing cataract surgery.

2.   Communicate realistic expected outcomes and potential complications to patients planning to undergo cataract surgery.

3.   Describe the design, mechanism of action, and utility of light adjustable lenses.

4.   Evaluate the risks and benefits of using femtosecond lasers for laser in situ keratomileusis (LASIK) surgery.

5.   Discuss the features of the current models of presbyopic intraocular lenses.

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. Goldman reported a consulting agreement with Alcon and is on the Speakers’ Bureaus of Alcon and Ad­vanced Medical Optics. Drs. Galor, Krueger, and Forster, and the planning committee reported nothing to disclose.

Acknowledgements

Lectures by Drs. Galor, Forster, Krueger, and Goldman were recorded at the Cataract and Refractive Surgery Congress, held February 6-7, 2000, in Miami, FL, and presented by the Bascom Palmer Eye Institute, University of Miami Miller School of Medicine. The Audio-Digest Foundation thanks the speakers and the Bascom Palmer Eye Institute for their cooperation in the production of this program.

The Uveitic Cataract: Medical and Surgical Recommendations

Anat Galor, MD, Assistant Professor of Clinical Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL

Recommendation: cataract surgery contraindicated in patients with active uveitis; exceptions include phacoantigenic uveitis (surgery mandatory and curative), cases in which posterior segment pathology requires surgery and cataract impairs visualization of posterior pole, and cases in which inflammation controlled for ³3 mo

Diagnosis and evaluation: diagnosis determines surgical plan (eg, patients with Fuchs’ heterochromic cyclitis vs ju­venile rheumatoid arthritis); identify ocular complications associated with uveitis that determine outcome (eg, glau­coma, macular edema, retinopathy); discuss prognosis after surgery with patients

Inflammation: normal eyes  —  have tolerance, ie, if antigen presented by antigen-presenting cell (APC), T cells sup­pressed; if more antigen presented, T cells undergo cell death; system protects eye from inflammation; surgical inflammation  —causes release of cytokines and survival signals that reduce protection; patients with uveitis  —  protective mechanisms compromised, and surgery causes more inflammation than expected

Controlling inflammation: results in absence of active anterior chamber or vitreous cells; flare indicates chronicity, not active inflammation

Corticosteroids: first-line therapy; critical to suppress all inflammation, then taper and discontinue; dosing every 1 to 2 hr provides control of inflammation and allows more rapid subsequent reduction in dose

Systemic immunosuppressive therapy: needed immediately for disorders including Behçet’s syndrome, necrotizing scleritis and vasculitis, serpiginous choroidopathy, and mucous membrane pemphigoid; consider using for birdshot retinochoroidopathy, multifocal choroiditis and panuveitis, and sympathetic ophthalmia; patient compliance and monitoring of laboratory values essential; antimetabolites  —  eg, methotrexate, azathioprine, mycophenolate; T cell inhibitors  —  eg, cyclosporine, tacrolimus; alkylating agents  —  eg, cyclophosphamide, chlorambucil; used for more severe inflammation

Biologic response modifiers: block different parts of inflammatory pathway; eg, etanercept and infliximab (antibod­ies against tumor necrosis factor [TNF]) block induction of inflammation by TNF; daclizumab blocks interleukin-2 (IL-2) and prevents activation of more T cells

Plan: begin topical steroids 3 days before and oral steroids (1 mg/kg) 2 days before surgery; continue systemic immunosup­pression; during surgery, consider giving pulse of intravenous steroids; after surgery, give topical steroid every 1 to 2 hr, taper oral steroids over 3 wk, and adjust chemotherapy as needed

Surgical techniques: most patients with uveitis have posterior synechiae and small pupils; good exposure necessary; place intraocular lens (IOL) in capsular bag; placing lens in ciliary sockets in anterior chamber irritating to iris

Case example: 72-year-old woman underwent uncomplicated cataract surgery; achieved visual acuity (VA) of 20/20 at 1 wk after surgery; 2 mo later, patient had pain, fluctuating vision, and mild anterior chamber reaction; patient restarted topical steroids and became cycloplegic; inflammation resolved; 3 mo later, patient had pain and VA of 20/25 with trace cells; no history of uveitis

Differential diagnosis: includes infections (eg, Propionibacterium acnes), sarcoidosis, HLA-B27, collagen vascular disease, and surgical causes

Laboratory results: positive fluorescent treponemal antibody (FTA) and reactive rapid plasma reagin (RPR) indi­cated syphilitic anterior uveitis

Challenging Cataract Cases

Richard K. Forster, MD, Professor of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine

Introduction: All cases follow-ups to cataract surgery; although surgeon recognized no intraoperative complications or problems, procedure resulted in patient unhappy with visual results (more likely related to perception of patient preoperatively than to results of surgery)

Case 1: 32-year-old woman with bilateral congenital cataracts; before surgery, patient’s VA 20/40 (20/70 with contact lenses); posterior subcapsular cataracts; patient expected not to need glasses after surgery, but postsurgical uncor­rected VA of 20/50(-2 at distance) in right eye and 20/40 in left; near VA (NVA) 20/70 and 20/50; refracted to 20/15 but postoperative astigmatism seen

Case 2: 81-year-old woman had excellent result from surgery in left but not right eye; bilateral toric IOLs implanted to correct astigmatism; after surgery, patient’s VA 20/80 in right eye and 20/25 in left eye; with correction, 20/25 +2 and 20/20; patient had residual refractive error with off-axis IOL

Case 3: 70-year-old woman; unhappy with surgical result because she was told right eye would be corrected for near and intermediate vision and the left eye for distance vision; expected to be corrected without need for spectacles; underwent IOL exchange 2 mo after surgery; patient’s vision improved with glasses, but patient remained dissatis­fied; patient’s uncorrected VA 20/20 -1 and 20/60 (after IOL exchange); with refraction, patient’s VA 20/15 and 20/20; patient also had spherical equivalent of 1/2 and -1/4

Case 4: 69-year-old woman; complained of monocular diplopia 6 mo after surgery; patient described ring above and below vision in right eye and half circle and ghosting in left eye; history  —  patient underwent upper and lower bilat­eral plugs but upper plugs removed because of foreign body sensation; patient given cyclosporine (Restasis), 1% azithromycin in DuraSite (AzaSite), and artificial tears without success; received diagnosis of bilateral epiretinal membranes; at presentation  —  patient had uncorrected VA of 20/50 +1 and 20/40 and corrected VA of 20/20 in both eyes; prisms did not affect monocular diplopia; problems specific to left eye  —abnormal eyelid and tear function and reduced tear break-up time; mild changes seen on corneal topography; optical coherence tomography (OCT) showed mild epiretinal membrane; diagnosis  —  nasally decentered multifocal IOL in right eye

Common features: all patients had expectations of seeing well without glasses or contact lenses after surgery; realis­tically, however, some patients require correction after surgery, regardless of technique used

Recommendations: advise patients before surgery of potential complications and set realistic expectations; surgeon should personally administer informed consent before surgery

The Light Adjustable Lens for Postoperative Refinement of Refractive Cataract Outcomes

Ronald R. Krueger, MD, MSE, Medical Director, Department of Refractive Surgery, Cole Eye Institute, Cleve­land Clinic, Cleveland, OH

Lens design: allows adjustment of postoperative vision without use of laser on cornea; made of photosensitive sili­cone, 6-mm optic, polymethyl methacrylate (PMMA) haptics; enables correction of myopia (£2 diopters [D]), hy­peropia, astigmatism, and aberrations; lens has UV-blocking layer to protect retina from UV light

Procedure: adjust 1 to 2 wk after surgery; determine patient’s satisfaction after 2 days to 1 wk, then lock in value

Mechanism: polymer matrix has macromers with polymerizable end groups that can move within lens; UV irradia­tion causes macromers to link onto matrix; remaining macromers then diffuse and cause lens to swell; process takes »24 hr

Optical quality: good resolution, based on United States Air Force target; modulation transfer function showed uni­form decay in overall response with small letter sizes; myopia correction  —  accurate correction achieved at changes of 0.5, 0.75, 1, and 1.25 D; hyperopia correction  — high modulation transfer functions achieved; good resolution (Air Force target), good predictability for changes of 0.5 0.75, 1, and 1.25 D; astigmatism  —  possible to remove power in one meridian and add perpendicularly to give neutral nonspherically changing astigmatism correction; aberrations  —  higher order aberrations (eg, trefoil projected and achieved by UV light) and spherical aberrations reduced to low values

Barriers to adoption: difficulty of predictably achieving emmetropia; centration; patient tolerance; explantation vs neuroadaptation; variability in pupil sizes

Adjustability: multifocal adjustments possible with customizable zones and power-adds (eg, bulls-eye design, power adjustments £3.5 D); can adjust to multiple zones or diffraction fringes

Study results: among 25 patients, 92% came within 0.25 D of spherical end point after surgery; 100% came within 0.5 D with no loss of best corrected vision and good cylindrical corrections

Regulatory status: approved in Europe; phase II trials under way in United States

Monovision: also possible; possibly better tolerated than multifocal vision

Femtosecond Laser In Situ Keratomileusis (LASIK) Complications

Dr. Krueger

Flap characteristics: possible to achieve uniform thin planar flap; term sub-Bowman’s keratomileusis (SBK) indi­cates laser hugs Bowman’s layer; flaps between 90 and 110 mm in thickness

Advantages: microkeratomes make meniscus-shaped flap; more reproducible flaps made with femtosecond (FS) la­sers; FS lasers produce low level of biomechanical effects, lower incidence of dry eye, better corneal sensation, and more residual stromal bed, with possibly lower risk for ectasia

Case example: patient in study treated in one eye with microkeratome, and in other eye with blade-free technique (IntraLase Method); 1 mo later, flap lifted and measured; eye treated via blade-free technique had 10-mm difference in thickness of cornea from center to periphery; eye treated with microkeratome had 90-mm difference; more pe­ripheral steepening in corneal topography found with microkeratome; slight shift toward hyperopia occurred, pre­dominantly in microkeratome eye, leading to more spherical aberration; after treatment, both eyes had good result, but greater number of higher order aberrations found in eye treated via microkeratome

Comparative studies: study of »200 eyes showed similar VA at 3 mo, with less spherical aberration created by blade-free technique and improved low-contrast vision; less loss of corneal sensation at 1 mo

Limitations on thickness of flap: retrospective study of patients with 90-mm flaps vs those with 100- to 110-mm  flaps; 90-mm setting led to mean flap thickness of »81 ± 8.9 mm; 32 eyes had interphase haze at 3 mo (trace up to 3+ haze); 91% of these had thinner flaps and slightly higher corrections; concluded that 90 mm slightly too thin

Side effects and complications: include interphase inflammation, opaque bubble layer (OBL), bubble breakthrough, flap tears, tracking problems, rainbow glare, diffuse lamellar keratitis, and transient light sensitivity syndrome; in­flammation decreased with more modern lasers; OBL  —  force of bubbles leads to extension into underlying stroma, periphery and Schlemm’s canal, anterior chamber, and subconjunctival space; may cause some light sensitivity; study  —  among 3000 SBK procedures with thin flaps, overall complication rate 0.63%; flap-tear and bubble escape occurred in only 0.33%; photoablation plane created so light scatter can occur; »7.2% of patients see multiple lights around edge of point light source

Advances in Presbyopic IOLs

David A. Goldman, MD, Assistant Professor of Clinical Ophthalmology, Bascom Palmer Eye Institute, Univer­sity of Miami Miller School of Medicine

Accomodating IOL (Crystalens HD): shape of surface (thickening on central optic) enhances depth of focus; study  —  130 patients received bilateral implants; 100% had ³20/40 VA, 90% had ³20/30, >50% had 20/25, and <50% had 20/20 VA; majority had 20/25 intermediate VA, and 80% had 20/20; for NVA, 100% at J3, 80% at J2, and 55% at J1; new model produced »1-line improvement in near vision

Multifocal IOLs

Acrysof IQ Restor +3.0 D: provides 2.5 D of spectacle plane vs 3.2 D provided by previous +4 model; 3.6-mm apo­dized central diffractive structure with 1.3 to 0.2 mm steps between steps (ie, 9 steps vs 12 in previous model); central zone diameter slightly larger; study  —  300 patients bilaterally implanted with either +3 or +4 model; pa­tients saw improvement in intermediate VA (65% had 20/25); NVA equal, but best focal image moved out 6 to 7 cm with  +3; similar rates of glare and halos; new lens produced »1- to 1.5-line improvement in intermediate vi­sion

Tecnis Multifocal (Advanced Medical Optics [AMO]): full diffractive surface and pupil-independent; wave-front aspheric surface; optical power of »+4; posterior refractive surface to reduce chromatic aberration; study  —  121 patients implanted bilaterally with multifocal lenses and compared to 122 with monofocal lenses; nearly 100% of patients had uncorrected distance VA of ³20/30, 86% had 20/25, and »60% had 20/20; testing showed NVA of 20/30 in 96.5% of patients, 20/25 in 70.2%, and 20/20 in »40%; »85% reported never wearing glasses, 4% wore glasses sometimes, and 1.8% always

Suggested Reading

Abbott RL: Informed consent in cataract surgery. Curr Opin Ophthalmol 20:52, 2009; Buznego C, Trattler WB: Presby­opia-correcting intraocular lenses. Curr Opin Ophthalmol 20:13, 2009; Chang JS: Complications of sub-Bowman’s ker­atomileusis with a femtosecond laser in 3009 eyes. J Refract Surg 24:S97, 2008; Chayet A et al: Correction of residual hyperopia after cataract surgery using the light adjustable intraocular lens technology. Am J Ophthalmol 147:392, 2009; Co­chener B et al: Corrected and uncorrected near and distance vision with ReSTOR compared to monofocal intraocular lens implantation after cataract surgery: a pooled analysis. Ophthalmologica 223:77, 2009; De Croos FC, Afshari NA: Periop­erative antibiotics and anti-inflammatory agents in cataract surgery. Curr Opin Ophthalmol 19:22, 2008; Kaiser I et al: In­cidence, possible risk factors, and potential effects of an opaque bubble layer created by a femtosecond laser. J Cataract Refract Surg 34:417, 2008; Kalyani SD et al: Intraocular lens power calculation after corneal refractive surgery. Curr Opin Ophthalmol 19:357, 2008; Kim SJ, Bressler NM: Optical coherence tomography and cataract surgery. Curr Opin Ophthal­mol 20:46, 2009; Maxwell WA et al: Performance of presbyopia-correcting intraocular senses in distance optical bench tests. J Cataract Refract Surg 35:166, 2009; Montes-Mico R et al: Analysis of the possible benefits of aspheric intraocular lenses: review of the literature. J Cataract Refract Surg 35:172, 2009; Montes-Mico R et al: Intraocular lens centration and stability: efficacy of current techniques and technology. Curr Opin Ophthalmol 20:33, 2009; Soong HK, Malta JB: Femto­second lasers in ophthalmology. Am J Ophthalmol 149:189, 2009; Sutton G, Hodge C: Accuracy and precision of LASIK flap thickness using the IntraLase femtosecond laser in 1000 consecutive cases. J Refract Surg 24:802, 2008; Van Gelder RN, Leveque TK: Cataract surgery in the setting of uveitis. Curr Opin Ophthalmol 20:42, 2009; von Jagow B, Kohnen T: Corneal architecture of femtosecond laser and microkeratome flaps imaged by anterior segment optical coherence tomogra­phy. J Cataract Refract Surg 35:35, 2009; Zaborowski AG et al: Cataract surgery in pediatric uveitis. J Pediatr Ophthal­mol Strabismus 45:270, 2008.