corneal scarring

[baldilocks]

Thanks to eye medications containing benzalconium chloride to which I appear to be allergic, I have a deterioration of vision due to scarring.  The visual effect is similar to that caused by keratoconus (see Wikipedia http://en.wikipedia.org/wiki/File:Kc_simulation.jpg) and for point of light, I see about 5 degraded images (again see Wikipedia http://upload.wikimedia.org/wikipedia/en/thumb/d/d7/Kc_simulation2.png/220px-Kc_simulation2.png).  When travelling in the car, I have difficulty identifying speed limit signs showing anything from 30, 50, 60, 80,90 since they all look like a blurred 80 until I am about 5 yards from them which is not satisfactory for driving purposes.  When I saw the ophthalmologist last I complained about my visual deterioration and he said it was due to the scarring and nothing could be done.  Looking at keratoconus and other corneal defects and the treatments for them, I wonder of either a corneal implant or a contact lens could counter the effects of the scarring.  Your advice would be most welcome.

[Houman Vosoghi, MD]

BAK drops shouldn't have lead to corneal scarring.  You need to see a corneal specialist. There is a chance that a RGP contact lens or corneal procedure can help.

HV

[baldilocks]

Re: the ill effects of Benzalconium chloride this is from an American Safety Data sheet for the substance concerned:

"SECTION VII - HEALTH HAZARDS AND FIRST AID
Effects of Overexposure:
Skin: Skin irritant. Prolonged or repeated contact may cause dermatitis.
Eyes: Severe eye irritant. Liquid and mists may injure the eyes causing corneal damage.
Inhalation: Mists are irritating to throat, nose and lungs.
Ingestion: Irritating to the mouth, throat, and gastrointestinal system. Burning, pain, and diarrhea expected with large doses."

and the stuff is in medication prescribed for actually putting in my eyes twice a day, that is four doses per day of something which "may cause corneal damage"

[baldilocks]

The drops I was prescribed were Brinzolamide and Brimonidine bothe of which contain Benzalconium chloride as a preservative.  I know from my work on dangerous substances that BAK is nasty stuff.  I'm now prescribed Travatan and Timogel which are both BAK free and I now have no pain but, of course, the damage has been done.  I have an appointment on Monday for corneal topographical mapping to assess whether a contact lens is likely to help.