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

Parag A. Majmudar, MD, Associate Professor of Ophthalmology, Rush University Medical Center, Chicago Cornea Consultants, Chicago, IL

Educational Objectives

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

1.   Describe the risk factors for cystoid macular edema and the appropriate use of prophylactic therapy to avoid it.

2.   Prescribe appropriate thermal, mechanical and pharmaceutical treatment of Meibomian gland dysfunction.

3.   Implement measures to improve outcomes and levels of patient satisfaction with presbyopia-correcting intra­ocular lenses.

4.   Choose the appropriate patients and optimal dosing regimens for the prophylactic use of mitomycin-C during refractive surgery.

5.   Avoid and/or manage serious complications associated with LASIK and Epi-LASIK.

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. Majmudar reported serving on the Speakers’ Bureau for Al­lergan, Alcon, AMO/VISX, Inspire, IOP, Ista, and Bausch and Lomb. The planning committee reported nothing to disclose. Dr. Majmudar presented information related to off-label or investigational use of a therapy, product, or device.

Acknowledgements

Lectures by Dr. Majmudar were recorded at the Cataract and Refractive Surgery Congress, held February 6-7, 2009, in Miami, FL, and presented by the Bascom Palmer Eye Institute, University of Miami Miller School of Medicine. The Audio-Digest Foundation thanks Dr. Majmudar and the Bascom Palmer Eye Institute for their cooperation in the production of this program.

Optimizing Outcomes in Cataract andRefractive Surgery

Background: patients generally dissatisfied with outcome if ³0.75 to 1.0 diopter (D) of residual astigmatism remains after cataract surgery; important to consider preoperative and surgically induced astigmatism; corneal topographic analysis essential for patients receiving toric lenses and premium intraocular lenses (IOLs); patients who have forme fruste keratoconus or other types of asymmetric astigmatism need preoperative and postoperative counseling about possible need for intraoperative limbal relaxing incisions (LRI) or refractive procedures after surgery; pearls for optimizing outcome  —  use nonsteroidal anti-inflammatory drops (NSAIDs) before and after surgery; normalize ocular surface

Cystoid Macular Edema (CME)

Risk factors: include preexisting ocular inflammation, loss of vitreous during surgery, diabetes, and stretching of iris; patients with no apparent risk factors can also develop CME

Study results: among patients at low risk for CME, 98% had leakage detected by optical coherence tomography (OCT) at 3 wk, and 22% showed retinal thickening at 30 wk after surgery; improved diagnostic techniques and higher surgical standards have lowered tolerance for retinal thickening; small changes in macula affect subjective quality of vision (eg, contrast sensitivity)

Prophylaxis: study results  —  significant difference found in incidence of CME between patients who received ste­roids only vs steroids plus NSAIDs; no patients who received ketorolac and steroids had definite CME, com­pared to 2.4% of patients with steroids only; patients with definite CME had £42 µ  of retinal thickening; minimizing retinal thickening improved contrast sensitivity at various frequencies; speaker prescribes NSAIDs to nearly all patients; pharmacoeconomics  —  Medicare claims amount to $3,000 per case per year, with reimburse­ments of $1,000 per year for each case of CME within 1 yr of surgery

Timing: study of NSAIDs administered 1 hr, 1 day, or 3 days before surgery; only pretreatment for 3 days produced no significant change in pupil size and better patient comfort during and after surgery; pretreatment for 1 or 3 days gave better visual outcomes immediately after surgery and reduced incidence of CME; speaker routinely prescribes NSAIDs for 3 days before surgery, longer if patients have vasculopathy, diabetes, or other preexisting conditions

Normalizing Ocular Surface

Background: tear film most important refracting surface of eye; even minimal disruption of ocular surface causes se­vere degradation of visual acuity (VA); lipid, aqueous, and mucin components balanced in normal tear film

Meibomian gland dysfunction (MGD): (ie, posterior blepharitis); treatment  —  warm eyelid; apply pressure (eg,  massage) to express glands; nutritional supplements may also improve ocular surface

Pharmaceutical treatment: tetracyclines  —  doxycycline at low dose (20-40 mg/day) preferable to 100 mg bid to minimize side effects; tetracyclines inhibit lipases and possibly matrix metalloproteinases to create anti-inflam­matory effects; corticosteroids  —  effective and show rapid onset; monitor intraocular pressure (IOP) and use pulsed doses; cyclosporine (Restasis)  —  study showed significant reduction of injection, tarsal telangiectasia, corneal staining, and Meibomian gland inclusions; other antibiotics  —  erythromycin ointment penetrates eyelid poorly; azalides, eg, azithromycin (Azasite), effective in penetrating eyelid and reducing inflammation (inhibits matrix metalloproteinases and bacterial lipases); speaker prescribes 4-wk course of treatment

Incorporating Presbyopia-correcting IOLs Into Your Practice

Background: Centers for Medicare and Medicaid Services (CMS) changed ruling for shared billing; new multifocal and accommodating IOLs available; growing market; cataract practices becoming more like refractive surgery practices

Quality: patients seek good outcome plus overall surgical experience; educate staff to communicate with patients about cataracts, IOL options, and financing; create realistic expectations about postoperative refractive enhance­ments, eg, laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) and possible need for glasses

Surgeon requirements: perfect biometry (ie, IOL master or immersion); regularly calibrate units for keratometry and topography; reduce preexisting and prevent surgically induced astigmatism

Patient selection: patients with extraordinary expectations and intolerance for minor problems or patients with com­promised visual system (eg, keratoconus or macular pathology) not good candidates

Lenses: types include multifocal, accommodative, and monovision; stratify benefits of lens types for different pa­tients on basis of age (eg, ReZoom for younger patients, ReSTOR 4.0 for patients who can tolerate closer focal point), pupil size, and need for functional intermediate vision; avoid multifocal lenses for patients with nighttime occupations; speaker uses questionnaire to determine type of vision patient expects and needs

Refractive lens exchange (RLE): patients undergoing RLE typically younger, more active, use computers more, and pay out of pocket; likely to compare results to good preoperative best corrected VA (BCVA); ReSTOR 3.0, Crystal­ens, or ReZoom useful for younger patients because of improved intermediate vision

Mitomycin-C in Refractive Surgery

Background: use of mitomycin-C (MMC) to promote healing and for surface ablation not approved; haze after PRK not prevalent, but surface ablations performed more often and used in complicated cases, eg, LASIK buttonholes and after radial keratotomy (RK) or penetrating keratoplasty; 83% of refractive surgeons use MMC; acts as antibi­otic and alkylating agent that inhibits DNA synthesis; previously used in glaucoma filtration surgeries

Case series: treated 21 patients (24 eyes) with subepithelial fibrosis after PRK or RK by removing epithelium and fi­brosis manually with blade or pterygium burr, and using corneal light shield soaked in MMC for 2 min to promote healing; prescribed steroid and fluoroquinolone after surgery; some patients in series had trace haze remaining; most improved 7 to 10 lines of Snellen acuity; no complications

Prophylactic MMC: speaker initially applied MMC for 2 min at concentration of 0.02% in patients at high risk of developing haze after PRK; study of decreased exposure time  —  among 269 eyes, treated one group with MMC for 120 sec before PRK, one group for 60 sec, and one group for 12 sec; enrollment criteria included planned ablation depth of ³75 m (depth of ablation indicates amount of energy delivered to cornea); outcomes good for haze and VA; only 1 patient had 1+ haze after 1 yr of follow-up; concluded 12 sec as effective as 120 sec; reduced concentration  —  in patients with lower myopia, 0.002% MMC appeared to work better than no MMC; but 0.02% appeared to work slightly better, especially in patients with high myopia (>-6.00 D)

Safety: delayed healing, corneal or scleral necrosis, and melting observed at high concentrations and exposure times or when MMC applied to limbus or sclera rather than cornea (eg, in pterygium or filtration surgeries); if MMC applied to central cornea at low concentration for short times, less delay in reepithelization occurs because MMC does not contact stem cells; speaker has used MMC for >12 yr with no complications; important not to exceed 0.02% (0.2 mg/mL) dose

Study of effect on corneal endothelium: morphometric analysis by specular microscopy before and »18 mo after PRK (with MMC applied for 12 sec) showed no significant difference between coefficients of variation of cells or percentage of hexagonal cells; other studies have shown no significant differences in endothelial cell counts; number of keratocytes decreased in stroma, although not significantly more than after PRK alone; unresolved whether keratocyte loss could lead to potential for ectasia

Other uses: MMC useful for treating patients with complications from LASIK (eg, buttonhole flaps or incomplete flaps) or after RK

Lasik Nightmares

Safety: United States Food and Drug Administration hearings on LASIK in 2008 confirmed safety of LASIK; never­theless, important to avoid complications

Case report 1: patient underwent LASIK for refractive error of 3.00 D, -1.00 D; operative notes stated that patient had tight fissures and keratome pass appeared to create no flap; surgeon adjusted diameter, added larger ring, and created nasally hinged flap; noted epithelial defect paracentrally after excimer laser ablation, so added bandage contact; also noted visible stroma instead of smooth Bowman’s membrane; actually, initial keratome pass created small free flap; several months later, slit lamp examination revealed large area of flattening; refractive error of +5.00 D, +4.50 D with BCVA of 20/80

Treatment options: rigid contact lens optimal until refraction stabilizes; wavefront-guided excimer ablation possi­ble, but refractive error exceeds custom approval; topographically-guided excimer ablation potentially helpful in future

Epi-LASIK: microkeratome used to separate epithelium and basement membrane from Bowman’s membrane with­out alcohol; hypothesis that retained basement membrane may result in better healing and less haze; theoretically as safe as PRK or laser epithelial keratomileusis (LASEK); if complications occur, replace epithelial and stromal tissue carefully and do not ablate cornea

Case report 2: Epi-LASIK for +1.00 D correction caused 3 x 5 mm central elliptical divot; surgeon performed abla­tion but did not replace flap or stromal divot; 3 mo after surgery, patient had poor vision; important to retain stroma if problem occurs

Stromal incursions: do not perform Epi-LASIK on patients with epithelial basement membrane dystrophy, recur­rent erosions, previous corneal surgery, or anterior stromal scars; management  —  recognize incursion, replace stroma and epithelium; place bandage contact lens; consider transepithelial PRK later

Case report 3: on first day after LASIK, patient had VA of 20/100 with corneal haze; differential diagnosis included pressure-induced stromal keratitis (PISK)  —  increased IOP may cause transudation of fluid through stroma, with epithelial and microcystic edema; if flap present, fluid transudated into flap may mimic diffuse lamellar keratitis (DLK); in this case, patient had normal IOP and problem developed rapidly after surgery; infection  —  patient had no true infiltrate and dry appearance; atypical inflammation usually shows less rapid onset; DLK  —  immune-me­diated response usually seen at 3 to 4 days

Central toxic keratopathy (CTK): shows well-demarcated white focal lesion with no inflammatory cells; opacity occurs either above or below interface (possibly full thickness), unlike DLK where opacity occurs late (stage IV) and confined to interface; loss of volume may result in central thinning and hyperopic shift; etiology  —  unknown (possibly caused by laser photoactivation of povidone-iodine); treatment  —  irrigation has no effect; steroids not indicated; observation preferred, but hyperopia and striae may remain after opacity clears; patient improved after 3 mo, with slight residual astigmatism

Case report 4: during ablation, surgeon noticed laser programmed for +6.00 D instead of planned -6.00 D; surgeon replaced flap, reprogrammed laser for correct parameters, then performed ablation of -6.00 D; patient had VA of counting fingers on first day after surgery, but vision improved after 1 wk; patient underwent enhancement later

Data entry errors: include transpositions (converting from plus cylinder to minus cylinder), omissions (dropping last zero in value), and use of wrong sign; preventing errors  —  have protocol in place for ensuring correct patient, cor­rect eye, correct parameters; have several staff members check and double check; in case of error  —  never hide mis­take from patient; be humble and apologetic; reassure patient that everything needed to change outcome will be done; follow patient frequently

Intraoperative pachymetry: speaker has used on all patients since 2000; helps to avoid ectasia; with modern micro­keratomes and femtosecond lasers, flap thickness more uniform and reproducible

Case report 5: patient with steep cornea underwent cataract surgery with ReSTOR and LASIK; because of hypero­pia, speaker used larger (9.5) ring, which has higher risk of creating buttonholes in steep corneas; buttonhole formed; PRK with MMC not possible because central buttonhole would not benefit from peripheral ablation; at 1 mo after buttonhole, speaker performed phototherapeutic keratectomy (PTK) centrally, then PRK for hyperopic correction; patient did well anatomically (no corneal scarring); buttonhole resolved; refractive error of +3.00 D; wears contact lens; considering piggyback IOL in future

Femtosecond lasers: generally good results; gas breakthrough can occur; DLK and epithelial ingrowth can occur with any keratome; rainbow glare and transient light sensitivity occur; lower incidence of flap complications with femtosecond lasers; study of 3009 eyes showed no major complications

Suggested Reading

Al-Mezaine HS et al: Incidence, management and visual outcomes of buttonholed laser in situ keratomileusis flaps. J Cata­ract Refract Surg 35:800, 2009; Ang EK et al: Outcomes of laser refractive surgery for myopia. J Cataract Refract Surg 35:921, 2009; Bollinger KE, Langston RH: What can patients expect from cataract surgery? Cleve Clin J Med 75:193, 2008; DeCroos FC, Afshari NA: Perioperative antibiotics and anti-inflammatory agents in cataract surgery. Curr Opin Ophthalmol 19:22, 2008; Donnenfeld E, Pflugfelder SC: Topical ophthalmic cyclosporine: pharmacology and clinical uses. Surv Oph­thalmol 54:321, 2009; Geggel HS: Treatment of lost flaps and slipped flaps. Int Ophthalmol Clin 48:17, 2008; Kashani S et al: Refractive lens exchange for presbyopia. Cont Lens Anterior Eye 31:117, 2008; Kim SJ, Bressler NM: Optical coherence tomography and cataract surgery. Curr Opin Ophthalmol 20:464, 2009; Lee JK et al: Microkeratome complications. Curr Opin Ophthalmol 20:260, 2009; Lemp MA, Nichols KK: Blepharitis in the United States 2009: a survey-based perspective on prevalence and treatment. Ocul Surg 4 (Suppl 2):S1, 2009; Leysen I et al: Surgical outcomes of intraocular lens exchange: five-year study. J Cataract Refract Surg 35:998, 2009; Neuhann IM et al: Online optical coherence pachymetry as a safety measure for laser in situ keratomileusis treatment in 1859 cases. J Cataract Refract Surg 34:1273, 2008; Salomao MQ, Wil­som SE: Corneal molecular and cellular biology update for the refractive surgeon. J Refract Surg 25:459, 2009; Solomon KD et al: LASIK World literature review: quality of life and patient satisfaction. Ophthalmology 116:691, 2009; Sonmez B, Malo­ney RK: Central toxic keratopathy: description of a syndrome in laser refractive surgery. Am J Ophthalmol 143:420, 2007; Talley-Rostov A: Patient-centered care and refractive cataract surgery. Curr Opin Ophthalmol 19:5, 2008; Teus MA et al: Mi­tomycin C in corneal refractive surgery. Surv Ophthalmol 54:487, 2009; Toda I: LASIK and the ocular surface. Cornea 27 (Suppl 1):S70, 2009; Trattler WB, Barnes SD: Current trends in advanced surface ablation. Curr Opin Ophthalmol 19:330, 2008.