Clouding is one of the most common troubleshoot problems associated with scleral contact lens fitting.
First, determine if the clouding is due to poor wettability of the lens surface or clouding of the biofilm trapped between the lens bowl and ocular surface.
Poor wettability is seen as an inability of the tear film to bind to the front surface of the lens with associated deposits forming on the lens surface as the day progresses.
Poor wettability can have a number of causes:
- The most common cause of lens non-wettability is poor or damaged lens edges which can cause irritation to the bulbar conjunctiva leading to excessive mucous discharge and resultant lens coating to occur. Feel the lens edge with your fingers for any rough areas and examine the edge under the slit lamp for any cracks or chips. In many cases, hand rolling the lens edge will resolve the issue.
- Unmanaged GPC will result in excessive lid interaction with the edge of the lens causing mucous discharge and lens coating to occur. Try to determine the cause of the allergy, which can be related to either seasonal allergy or chemical allergy, for example, the cleaning solution. If the allergy source cannot be eliminated, treat the allergy with combination antihistamine/mast cell stabilisers, NSAID’s or anti-inflammatories.
- Advanced Meibomian Gland Disease (MGD) will ultimately lead to a not wetting lens surface due to the absence of the lipid layer. MGD require aggressive and long term treatment of the Meibomian glands to restore the lipid layer.
- Polish residue remaining on the lens after lens manufacture or lens modifications. To clean the lens surface follow the cleaning instructions as they are provided by the lens manufacturer.
Clouding of the biofilm
AKA Mid-day fogging
Clouding of the fluid captured between the scleral lens and the surface of the eye can also have multiple causes:
1.The most common reason is a lens fit with an excessive sagittal height clearance over the entire surface of the eye. Using the slit lamp or OCT determine the current PLTT value and reduce the overall lens SAG to allow for a final PLTT of 150 microns.
- Sensitivity to the insertion solution. Always use a non-preserved saline solution to insert the scleral lens into the eye. Partially or fully replacing the insertion saline with lubricating drops like Thera Tears or Xailin HA have been reported to be beneficial to some patients in reducing late afternoon clouding.
- SLZ is bearing down on the limbus. Choose the correct sized diameter scleral lens to avoid any lens bearing and mechanical insult to the limbal zone.