Glaucoma（青光眼）isamajorcauseofblindnessaroundtheworldespeciallyindevelopingcountries.TheWorldHealthOrganizationsaysglaucomaisagreaterpublichealthchallengethancataracts（白内障）becausetheblindnesscausedbythelattercanbecuredafteroperations.
Glaucomaisadiseasethatmakespeoplearoundtheworldlosetheirsightandtheyusuallydon’tevenknowtheyhavethediseaseuntilithaspermanentlydestroyedatleast40percentoftheirsight.Theprocessisusuallysopainlessandsubtle（不明显的）sopeopledon'tnoticeit.Actuallythesimplestmedicaltestcandiscoverit.
“ItistheleadingcauseofblindnessintheUnitedStates.InHispanicsandinAfrican-Americansit’sthesecondleadingcauseofblindnessandsoisthecaseintheChineseandIndians.”saidDr.AlanRobinaspecialistintreatingglaucoma.“Theglaucomaweseeinsub-SaharanAfricaisamuchmoreaggressiveblindingdiseasethantheglaucomaweseeinAmericansorevenAfrican-Americansin-theUnitedStates.”hesaid． ．
Dr.EricFleischeralsoseesthesedifferencesatMedstarWashingtonHospitalCenter.“PrettymuchanybodywhohasancestorsinAfricahasanincreasedchanceofdevelopingglaucoma.”Ageisanotherthingthatmayleadtoglaucomaalthoughpeopleofallagescangetit.
Glaucomaisagroupofdiseasesthatcommonlyproducepressureintheeye.Aneyeissortoflikeawatch.Andbehindthefaceofthewatchliquidismade.Itgoesthroughyourpupil（瞳孔）andintothefrontofthewatchbetweenthefaceandthecrystal．There'sanareaaroundtheedgeofthewatchthatdrains（使排出）theliquid.Whenthatdrainisblockedtheliquidcan'tleavetheeyeasfastasitisproduced.Therisingpressurewithintheeyedamagesandeventuallykillstheoptic（视觉的）nerve.Theresultisblindness.
Fortunatelyifcaughtearlyglaucomacanbecontrolled.Glaucomaisnotcurable.Butas researchersworldwideleanmoreaboutittheygrowmorehopefulthatglaucomacanonedaybecuredorevenprevented.
【小题1】Inwhichcountryisglaucomathebiggestdangertopeople’ssight?