WHAT’S LIVING ON YOUR CONTACT LENSES?

1. WHAT’S  LIVING  ON  YOUR  CONTACT  LENSES?   We’re  constantly  surrounded  by  microbes  that  can  eat  our  eyeballs,  but   that  doesn’t  usually  happen  unless  you  wear  contact  lenses.       Contacts  are  awesome,  but  anyone  who’s  worn  them,  knows  that  they  can   cause  problems,  like  redness  and  eye  pain.  But  the  most  serious  problem  is   something  called  “Microbial  Keratitis,”  which  is  an  infection  of  the  cornea.   The  cornea  is  the  clear  layer  that  is  considered  the  transparent  window  of   the  eyeball.    And  if  it  gets  infected  it  can  sometimes  lead  to  blindness.  Lots   of  different  germs  can  cause  keratitis:  bacteria,  fungi,  viruses  like  herpes,   and  even  amoeba.  The  interesting  thing  is  that  the  species  of  fungi,   amoeba,  and  bacteria  that  cause  the  disease  are  actually  found  all  over  the   place.  Literally.  For  example,  Pseudomonas  aeruginosa,  which  is  the  most   common  keratitis-­‐causing  bacteria,  is  actually  found  in  tap  water  and  on   the  lettuce  in  your  fridge!  But  if  these  bugs  are  so  prevalent,  why  aren’t  we   constantly  getting  infections?         Great  question.  Well,  because  our  eyes  are  really  important  for  our   survival,  we’ve  developed  lightning  quick  defenses  to  kill  most  germs  that   land  there.  In  fact,  these  defenses  are  so  good  that  by  studying  the  eye,   scientists  are  starting  to  learn  some  secrets  for  keeping  other  parts  of  our   body  pathogen-­‐free.  The  problem  is  that  these  super  prevalent  microbes   are  super  prevalent  because  they’re  awesome  at  adapting  to  new   situations.  

2.   So  when  you  trap  them  against  your  eye  with  a  contact  lens  for  hours  on   end,  you  could  essentially  be  selecting  for  bugs  that  can  survive  this  really   harsh  environment.  The  few  that  make  it  actually  like  it  there  and  keep  on   replicating.  To  make  matters  worse,  when  you  remove  your  lenses  and   leave  them  to  soak,  you  may  be  selecting  for  bugs  that  can  survive   antimicrobial  solutions,  as  well!  Eventually,  these  superbugs  might  start   eating  their  way  through  your  cornea.       If  you  feel  any  discomfort  in  your  eye,  like  if  it  feels  like  there’s  something   stuck  in  there  even  after  you  take  out  your  lenses  and  that  feeling  just   seems  to  get  worse,  keep  those  lenses  out  of  your  eyes  and  let  your  doctor   know.  If  you  wait  too  long,  your  body’s  inflammatory  response  can  kick  in,   which  can  cause  its  own  damage.  In  fact,  it’s  sometimes  the  inflammation,   and  not  the  amoeba  or  bacteria,  that  finally  causes  blindness.     Keratitis  only  affects  about  0.2%  of  people  who  wear  contact  lenses  on  an   extended  basis.  But  for  those  who  get  it,  it  can  be  extremely  serious,  so   scientists  are  studying  how  to  prevent  it  altogether.  But  in  the  meantime,  if   you’re  a  contact  lens  wearer,  what  can  you  do  to  prevent  keratitis?     Well,  it's  not  foolproof,  but  wearing  the  type  of  lenses  you  throw  out  at  the   end  of  each  day  could  help.  And  of  course  follow  your  doctor’s  instructions.