GP Lens Case Grand Rounds Troubleshooting Guide – 09

Poor Acquired Vision: Manuel Conde, OD

Background

JB was a 25-year-old male who had been wearing silicone/acrylate (S/A) gas-permeable (GP) lenses for the past eight years. He came to the office complaining of reduction of vision for several weeks with his current GP lenses. His lenses were approximately 1 ½ years old.

Test Procedures, Fitting/Refitting, Design and Ordering

Visual Acuities (with Contact Lenses):

OD: 20/30+ Over-refraction: -0.50 DS 20/25
OS: 20/30 Over-refraction: -0.25 DS 20/25

Slit Lamp Examination:

Both lenses exhibited mucoprotein deposits on the anterior lens surface. In addition, both lenses had scratches on anterior lens surface. Both lenses decentered superior decentration on the eye.

With verification of the lenses there was no evidence of base curve toricity or power change.

Patient Consultation and Education

Patient was re-instructed about lens care and possibility of re-fitting with new lens material. Several procedures were made to solve JB’s complaints. First the lens was cleaned with a laboratory cleaner.

Second, in-office polishing of the anterior lens surface was made to reduce some scratches. Third a re-fitting with a fluoro-silicone/acrylate lens material was performed. It is also important in these cases for patients to be educated to clean the lenses in an up and down/back and forth manner in the palm of the hand immediately upon removal in the evening.

Follow-Up Care/Final Outcome

With the combination of patient education and in-office polishing, the surface problems noticeably improved. Visual acuity was improved to 20/20 OD and OS. He was able to wear these lenses comfortably until his new lenses arrived. With long-term wear of the F-S/A lenses, this problem did not recur.

Discussion, Alternative Management Options

Acquired reduced visual acuity is most commonly caused by mucoprotein film or haze on the anterior lens surface. Temporary relief can often be provided via the use of in-office laboratory cleaning such as that provided with the Boston Laboratory Cleaner (Bausch & Lomb) or Fluoro-Solve (Paragon Vision Sciences). In-office polishing is often not necessary although is often beneficial when a laboratory cleaning is unable to remove the entire muco-protein film. Fluorine-containing GP lens materials often exhibit superior surface wettability via the ability to maintain the tear film mucin on the lens surface for a longer time period than with their S/A counterparts.

Another common cause of acquired reduction in vision in GP wearing patients is lens warpage. Although the materials in common use today exhibit better memory than the previous generation of lens materials, lens warpage always needs to be ruled out. It can be problematic with patients accustomed to cleaning their lenses digitally (i.e., between the fingers) as opposed to in the palm of the hand. More flexible GP lenses such as high and hyper Dk lens materials exhibit more potential for this problem than low Dk lens materials.

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