LASIK

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0 height="100%"><tr> <td valign="top" width=210 BGCOLOR="#FFFFFF" TEXT="#080000" bgproperties="fixed" background="112f2f02egerdp.jpg"> <div> <A HREF="index.htm" TARGET="_top" TITLE="_"><U><B><U>HOME</U></B></U></A></div> <div> <TABLE BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="172" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP BGCOLOR=#66FFFF HEIGHT= 23 WIDTH="172"><div> <A HREF="id91.htm" TARGET="_top" TITLE="BRUCE ROSEMAN, M.D. 140 WEST 86th Stree"><U>CONTACT ME</U></A></div> </tD> </tR> <tR> <tD VALIGN=TOP BGCOLOR=#FFCC99 HEIGHT= 23 WIDTH="172"><div> <A HREF="id17.htm" TARGET="_top" TITLE="office info"><U>OFFICE INFO</U></A></div> </tD> </tR> <tR> <tD VALIGN=TOP BGCOLOR=#FFFF99 HEIGHT= 24 WIDTH="172"><div> <A HREF="id116.htm" TARGET="_top" TITLE="MEDICATION INFORMATION"><U>DRUG INFO</U></A></div> </tD> </tR> <tR> <tD VALIGN=TOP BGCOLOR=#66FF99 HEIGHT= 23 WIDTH="172"><div> <A HREF="id77.htm" TARGET="_top" TITLE="kids"><U>KIDS</U></A></div> </tD> </tR> <tR> <tD VALIGN=TOP BGCOLOR=#66FFCC HEIGHT= 23 WIDTH="172"><div> <A HREF="id24.htm" TARGET="_top" TITLE="SPECIALISTS"><U>SPECIALISTS</U></A></div> </tD> </tR> <tR> <tD VALIGN=TOP BGCOLOR=#FFFF99 HEIGHT= 23 WIDTH="172"><div> <A HREF="id75.htm" TARGET="_top" TITLE="research"><U>LOOK IT UP</U></A></div> </tD> </tR> <tR> <tD VALIGN=TOP BGCOLOR=#33CCFF HEIGHT= 44 WIDTH="172"><div>  <A HREF="id89.htm" TARGET="_top" TITLE="TEST YOURSELF"><U>TEST YOURSELF</U></A></div> </tD> </tR> <tR> <tD VALIGN=TOP BGCOLOR=#FFFFCC HEIGHT= 23 WIDTH="172"><div> <A HREF="id23.htm" TARGET="_top" TITLE=" RADIOLOGY AND IMAGING"><U>RADIOLOGY</U></A></div> </tD> </tR> <tR> <tD VALIGN=TOP BGCOLOR=#FF99FF HEIGHT= 23 WIDTH="172"><div> <A HREF="id47.htm" TARGET="_top" TITLE="HANDOUTS "><U>HANDOUTS </U></A></div> </tD> </tR> <tR> <tD VALIGN=TOP BGCOLOR=#FFCC99 HEIGHT= 23 ><NOBR><div>  I<A HREF="id53.htm" TARGET="_top" TITLE=" ANATOMY"><U>LLUSTRATIONS</U></A></div> </NOBR></tD> </tR> <tR> <tD VALIGN=TOP BGCOLOR=#33FFFF HEIGHT= 23 WIDTH="172"><div> <A HREF="id22.htm" TARGET="_top" TITLE="PHARMACIES"><U>PHARMACIES</U></A></div> </tD> </tR> </TABLE></div> <bR> <bR> <bR> </td> <td valign="top" BGCOLOR="#FFFFFF" TEXT="#080000" bgproperties="fixed" background="115f0f03.jpg"> <div> <I>LASIK</I></div> <div> <B><U>LASIK AND ITS ALTERNATIVES: AN UPDATE</U></B></div> <div> Since the last Medical Letter article on surgical correction of refractive errors <FONT SIZE="3" COLOR="#0000FF" FACE="Univers" >(Volume 41,</FONT></div> <div> page 122, 1999)<FONT SIZE="3" COLOR="#000000" FACE="Univers" >, some new techniques have been tried and new results have been reported.</FONT></div> <bR> <div> <B><U>LASIK</U></B><B> </B></div> <div> <B> </B><FONT SIZE="3" COLOR="#000000" FACE="Univers" >In laser in-situ keratomileusis (LASIK), the most frequently performed refractive</FONT></div> <div> surgery procedure for low to moderate myopia, a microkeratome is used to make a thin lamellar</div> <div> flap on the corneal surface. The flap is retracted and an excimer laser programmed to correct the</div> <div> patient's myopia, hyperopia and/or astigmatism is used to remove a specific pattern of corneal tissue</div> <div> from the stromal bed. The flap is then repositioned without need for suturing. Following the</div> <div> procedure, most patients recover full vision within 48 hours, although full stabilization may take 3</div> <div> months. To achieve the desired correction, 5% to 28% of patients require a second lifting of the flap</div> <div> and reshaping of the corneal tissue, known as an "enhancement," usually 3-6 months after the first</div> <div> procedure <FONT SIZE="3" COLOR="#0000FF" FACE="Univers" >(PS Hersh et al, Ophthalmology 2003; 110:748)</FONT>.</div> <div> The largest series reported to date included 2100 consecutive LASIK procedures and found</div> <div> that about 60% of eyes with low myopia (<7 diopters) and 45% of eyes with high myopia (>7</div> <div> diopters) achieved 20/20 or better uncorrected vision. More than 90% of eyes with low myopia and</div> <div> 84% with high myopia achieved 20/40 or better uncorrected vision, which is legally acceptable for</div> <div> driving (GO Waring III et al, Invest Ophthalmol Vis Sci 1999; 40:S588, abstract 3088).</div> <bR> <div> <B><U>Wavefront Technology</U></B></div> <div> <B> </B><FONT SIZE="3" COLOR="#000000" FACE="Univers" >In recent years, development of more precise corneal scanning systems</FONT></div> <div> (aberrometers) that create a better map of the patient?s refractive irregularities has improved</div> <div> assessment of corneal aberration. This "wavefront-guided technology," along with improved microkeratomes,</div> <div> better eye-tracking with the laser and more precise registration from the aberrometer to</div> <div> the laser, is claimed to have improved outcomes and decreased the need for enhancements <FONT SIZE="3" COLOR="#0000FF" FACE="Univers" >(S</FONT></div> <div> Waheed and RR Krueger, Curr Opin Ophthalmol 2003; 14:198)<FONT SIZE="3" COLOR="#000000" FACE="Univers" >, but supporting data from patients</FONT></div> <div> with comparable degrees of myopia and astigmatism are limited. One small study of 31 eyes using</div> <div> the CustomCornea aberrometer (Alcon) found that 84% of eyes (26/31) had 20/20 uncorrected vision</div> <div> 3 months after treatment <FONT SIZE="3" COLOR="#0000FF" FACE="Univers" >(MA Lawless et al, J Refract Surg 2003; 19:S691)</FONT>. A small comparative</div> <div> study in 12 patients who had standard LASIK in one eye and LASIK using the Zyoptixwavefront</div> <div> aberrometer (Bausch and Lomb) in the contralateral eye found that 6 months after the procedure</div> <div> 100% of eyes in both groups had at least 20/40 uncorrected vision; 8 eyes (67%) treated with Zyoptix</div> <div> and 10 (83%) with standard LASIK had 20/20 uncorrected vision <FONT SIZE="3" COLOR="#0000FF" FACE="Univers" >(RM Nuijts et al, J Cataract Refract</FONT></div> <div> Surg 2002; 28:1907)<FONT SIZE="3" COLOR="#000000" FACE="Univers" >. According to The Wall Street Journal (January 6, 2004), wavefront technology</FONT></div> <div> can add $100 to $400 to the cost ($500 to $2500 per eye) of conventional LASIK.</div> <bR> <div> <B><U>Adverse Effects </U></B></div> <div> Glare, halos and starbursts around lights at night are frequent after</div> <div> LASIK. They tend to disappear after a few months, but some patients may continue to have vision</div> <div> problems at night or in dim lighting <FONT SIZE="3" COLOR="#0000FF" FACE="Univers" >(MD Bailey et al, Ophthalmology 2003; 110:1371; M Pop and Y</FONT></div> <div> Payette, Ophthalmology 2004; 111:3; SC Schallhorn et al, Ophthalmology 2003; 110:1606)<FONT SIZE="3" COLOR="#000000" FACE="Univers" >.</FONT></div> <div> Theoretically wavefront technology could diminish the risk of developing these effects, but evidence</div> <div> is lacking. Dry eye symptoms including pain and the sensation of eyelids sticking to the eyeball are</div> <div> common and may persist for months.</div> <div> Overcorrections and undercorrections occur, but they can often be repaired. Induced astigmatism</div> <div> can also occur. Complications related to the corneal flap, such as displacement or folds, occur in</div> <div> 0.5% of cases; they usually develop immediately after surgery, can be repaired and generally are not</div> <div> vision-threatening. A tear in the flap (?buttonhole?) may prevent correction, and scarring can lead to</div> <div> decreased vision. The risk of a vision-threatening infection after LASIK is 1 to 5 per 10,000 procedures.</div> <div> About 3% of patients who have had LASIK have lost two or more lines (eg, from 20/20 to</div> <div> 20/40) of best spectacle-corrected visual acuity; patients who need high levels of visual acuity, such</div> <div> as pilots or surgeons, may find even such small reductions debilitating. Fewer than 0.5% of patients</div> <div> have been left with best spectacle-corrected vision of less than 20/40. Whether wavefront technology</div> <div> will improve these numbers remains to be established.</div> <bR> <div> <B><U>PRK</U></B><B> </B></div> <div> Photorefractive keratectomy (PRK) also uses a laser to reshape the stromal surface</div> <div> of the cornea, but unlike LASIK does so without a corneal flap. The epithelium is removed with a</div> <div> spatula, brush or 20% alcohol solution before the laser corrects the refractive error. Re-epithelialization</div> <div> is required to cover the defect after surgery and for this reason PRK can cause considerable</div> <div> postoperative discomfort. In addition to discomfort, relative disadvantages are prolonged recovery</div> <div> of vision and, in some patients, central haziness caused by subepithelial healing <FONT SIZE="3" COLOR="#0000FF" FACE="Univers" >(MR Chalita et al,</FONT></div> <div> J Refract Surg 2003; 19:412)<FONT SIZE="3" COLOR="#000000" FACE="Univers" >. Advantages of PRK include greater safety in thin corneas and corneas</FONT></div> <div> with epithelial adhesion problems.</div> <bR> <div> <B><U>CK </U></B></div> <div> Conductive keratoplasty (CK) has been approved by the FDA for correction of hyperopia</div> <div> of +0.75 to +3.25 diopters in patients 40 years of age or older <FONT SIZE="3" COLOR="#0000FF" FACE="Univers" >(MB McDonald et al, Ophthalmology</FONT></div> <div> 2002; 109:1978)<FONT SIZE="3" COLOR="#000000" FACE="Univers" >. Under topical anesthesia, CK probes deliver radiowaves to spots along the circumference</FONT></div> <div> of the cornea. Consequent collagen shrinkage at the treatment sites leads to a biomechanical</div> <div> purse string effect, causing steepening of the central cornea to correct farsightedness. Applications of</div> <div> CK to correct reading vision are currently being investigated. One advantage of CK over LASIK or PRK</div> <div> is that the central cornea is left intact. Disadvantages include inability to correct higher degrees of</div> <div> hyperopia, induction of astigmatism, and regression of the corrective effect.</div> <bR> <div> <B><U>INTRACORNEAL RINGS </U></B></div> <div> The implantation of polymethylmethacrylate (PMMA) ring segments</div> <div> into the peripheral cornea to flatten the anterior curvature of the central cornea can correct</div> <div> low degrees of myopia (up to 3 diopters). An advantage of intracorneal rings is that they can be</div> <div> removed if the patient is unhappy with the results or experiences night vision problems. Removal</div> <div> usually restores the eye to its pre-operative refractive error, although glare and halos may persist.</div> <div> Since the rings are in the peripheral cornea, the risk of injury or scarring of the central cornea that</div> <div> can occur after laser refractive procedures is generally eliminated. Common complications include</div> <div> mild postoperative pain and occasional glare at night. Infection, astigmatism (which may be transient),</div> <div> and perforation of the anterior chamber requiring removal of the implants have been reported.</div> <div> Intracorneal rings account for only a small percentage of refractive surgery procedures today.</div> <bR> <div> <B>PHAKIC INTRAOCULAR LENSES ? </B></div> <div> Recent improvements in intraocular lens technology now</div> <div> permit implantation of plastic intraocular lenses without removing the natural lens. Plastic lenses are</div> <div> under investigation for correction of high myopia and hyperopia. The advantage of the phakic procedure</div> <div> is that it does not change the shape of the cornea. Some patients who did not achieve a satisfactory</div> <div> result from intraocular lenses have had LASIK as well, with good results <FONT SIZE="3" COLOR="#0000FF" FACE="Univers" >(GO Waring III,</FONT></div> <div> Ophthalmologica 2003; 217 suppl 1:32)<FONT SIZE="3" COLOR="#000000" FACE="Univers" >. Potential problems with phakic intraocular lenses include</FONT></div> <div> damage to the corneal endothelium, glaucoma, retinal detachment and cataract formation.</div> <bR> <div> <B><U>CONCLUSION </U></B><B> </B></div> <div> LASIK, the most common surgical procedure used for correction of vision</div> <div> in the US, is generally effective in patients with mild to moderate myopia; more than 90% of patients</div> <div> do not need full-time glasses or contact lenses postoperatively. About 3% of all patients treated with</div> <div> LASIK have lost two or more lines of best spectacle-corrected vision. Wavefront technology and</div> <div> other technical advances may be improving these outcomes, but published data are limited. PRK is</div> <div> similar in efficacy to LASIK, but causes more discomfort. CK, a newer procedure, is effective for</div> <div> lower degrees of hyperopia and is relatively noninvasive. Implantation of phakic intraocular lenses</div> <div> can correct high myopia or hyperopia; this procedure does not change the shape of the cornea and</div> <div> is reversible. The long-term risks of all of these procedures are unknown. None of them corrects loss</div> <div> of accommodation with aging, so most patients will still need reading glasses.</div> <bR> </td> </tr></table></body>