Cataracts:The Case for Earlier Surgery

December 31, 2006

Cataracts areone of themost importantcauses ofreversibleblindness in elderly persons.1 A recent report thatpredicts a surge in cataractincidence has heightenedawareness of the importanceof proper timing andtechniques for cataract extraction.The study, authoredby the Eye DiseasesPrevalence ResearchGroup, estimated that thenumber of Americans withcataracts will increase byapproximately 50% in thenext 20 years as the populationages.2 Cataracts werethe leading cause of low vision(less than 20/40 bestcorrected visual acuity inthe better-seeing eye)among whites, blacks, andHispanics.

Cataracts areone of themost importantcauses ofreversibleblindness in elderly persons.1 A recent report thatpredicts a surge in cataractincidence has heightenedawareness of the importanceof proper timing andtechniques for cataract extraction.The study, authoredby the Eye DiseasesPrevalence ResearchGroup, estimated that thenumber of Americans withcataracts will increase byapproximately 50% in thenext 20 years as the populationages.2 Cataracts werethe leading cause of low vision(less than 20/40 bestcorrected visual acuity inthe better-seeing eye)among whites, blacks, andHispanics.The group based itsfindings on the 2000 UScensus data and projecteddemographic figures for2020. According to thesedata, about 937,000 Americans(0.78%) 40 years orolder are blind (less than20/200 best corrected visualacuity in the better-seeing eye) and an additional2.4 million (1.98%)have low vision. About 20.5million Americans olderthan 40 years have a cataract;that number is expectedto rise to 30.1 millionby 2020.BLACKSPREFERENTIALLYAFFECTEDCataracts appear todisproportionately affectpersons of African origin.3,4The recent Barbados EyeStudies, a 9-year population-based cohort report,assessed the long-term patternsand incidence of lensopacities in a predominantlyblack population.5 Of the2793 Barbados-born participants,93% were black, 4% were of mixed race, and 3%were white or "other." Themean age was 56 years.The authors foundthat overall lens changeswere twice as likely--andcortical cataracts 3 timesas likely--to develop inblacks as in whites. Mostearlier large populationbasedstudies did not haveenough black participantsto allow meaningful conclusionsto be drawn.6,7 Otherstudies found that nuclearsclerotic cataracts weremore common in whites.8-10Cortical cataracts, whichare usually bilateral, are associatedwith increasedhydration of the lens fibers,which leads to corticalopacification (Figure).11These cataracts form spokes or wedge-shapedopacities that progressfrom the periphery to thecenter. Vision is most dramaticallyaffected with theinvolvement of the visualaxis. Cortical cataracts canprogress rapidly and causeglare.11,12In patients with nuclearsclerotic cataract--the other common cataractin elderly persons--nuclearsclerosis produces hardeningand discoloration of thewhole lens, which oftencauses lenticular myopia;this condition can be correctedwith glasses. Nuclearsclerotic cataractsgrow more slowly than corticalcataracts; moreover,because any new refractiveerror (myopic shift) can usually be corrected, nuclearsclerotic cataractsmay not affect vision untillater in life.The authors of theBarbados Eye Studies attributethe higher risk ofcortical cataract developmentin black persons tothe higher prevalence ofdiabetes, hypertension, andtruncal obesity in this population.Control of theseconditions might attenuatethe risk of cortical cataractsin this group. (Nuclearsclerotic cataracts arethought to be more stronglyassociated with aging.)The authors suggest thatuntil specific cataract preventionstrategies can beidentified and implemented,cataract surgery shouldbe used more widely in patientswho have cataractinducedvision loss.BENEFITS ANDRISKS OF SURGERYCataract surgery cansignificantly improve patients'quality of life, as wellas their safety, satisfaction,and ability to function.13,14With current techniques and instrumentation, thesuccess rate for cataractsurgery may be as highas 80% to 90%, dependingon the outcome measureused.13,14In the recent past,cataract surgery was a laboriousprocedure thatcaused significant emotionaland physical stress. Patientshad to wait until theircataract was "ripe"--that is,at a mature stage that resultedin significant visualdisability--before theycould have it removed. Today,many ophthalmologistsfeel that the timing ofcataract surgery should bebased primarily on the patient'sneeds, preferences,and functional limitations,in conjunction with thephysical findings (Box).15Elderly patients havebeen shown to benefit fromearlier cataract surgery. Ina prospective study of 277patients aged 55 to 84 yearswho had cataracts, thosewho underwent surgeryand intraocular lens implantationreduced by at least50% their risk of being in anautomobile accident comparedwith those who didnot have the procedure.16During the 4- to 6-year follow-up period, the accidentrate in the surgery groupwas 4.74 per million milesof travel compared with8.95 per million miles oftravel in the group that didnot have surgery.Several studies havefound an association betweencataracts and mortality.17-19 However, whenother systemic variablesand comorbid conditions(including age, race, sex,smoking status, atherosclerosis,diabetes, and hypertension)were takeninto account, only 1 studyconfirmed such an association.19 When specific causesof morbidity and mortality--such as falling inelderly persons--are evaluated,correction of visionloss, such as with cataractsurgery, shows directbenefit.20A recent study foundthat in patients who havecataracts and age-relatedmacular degeneration(AMD), cataract surgerymay be associated with a2 to 5 times greater risk oflate-stage AMD, particularlyneovascular or "wet"AMD.21 Almost all the patientsin whom wet AMDdeveloped after cataractsurgery during the 5-yearstudy period had some early-stage AMD lesionsat baseline. The authorssuggested that either thecataract surgery itself orchanged ocular conditions(eg, increased light exposure)hastened the progressionof AMD. Patientswith cataracts and AMDwho are contemplatingcataract surgery should beadvised of this risk.Other potential complicationsof cataract surgeryinclude posteriorcapsular opacification (althoughthis is readily correctedwith an in-officeyttrium-argon-garnet laserprocedure), endophthalmitis,cystoid macular edema,lost lens fragments, intraocularlens dislocation,retinal detachment, andpseudophakic bullouskeratopathy.

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