Case Studies using Silicone Hydrogel Lense

Susan R Bowers BSc(hons), FCOptom, Dip CLP, Dip Tp AS, FBCLA  

Susan graduated from Aston University and has practised in the West Midlands all her career. She passed her Therapeutics in 2006 and received her Fellowship of the British Contact Lens Association in 2008. She has just submitted her MSc thesis to City University.

Susan’s professional interests are varied. She is interested in Amblyopia due to Anisometropia and its treatment. Her recent work is on Intuitive Overlays and she enjoys challenging contact lens fitting, especially children and presbyopes. She is a newly elected member to the BCLA council.

Case Study One: Toric Silicone Hydrogel

Mrs K is a 41 year old microscopist. She can only see with one eye to drive and use the microscope at work. She struggles to play badminton and use the computer.

Contact Lens Fitting:

LE only one Silicone Hydrogel Toric: Power +0.50/-2.25 x 80 V/A 6/5

This patient has slight hayfever currently. She is wearing the lens for six nights a week on an extended wear. Her driving has increased from 6,000 miles per year to 9,000. She uses wetting drops on waking. The lens rotates 15 degrees temporally and is stable. She is able to use her binocular stereopsis on the microscope at work when screening for breast cancer.

Case Study Two: Toric Silicone Hydrogel

Mrs M is a 52 year old nystagmus patient. Her vision in spectacles was below 6/12 and she struggled to read a number plate. She only drove 1,000 mile per year.

Contact Lens Fitting:

Silicone Hydrogel Toric:
Power: RE -8.00 / -2.25 x 20 V/A 6/12+2
Power: LE -8.50/-2.25 x 170 V/A 6/9-1

This patient has much less nystagmoid tremor with the biofeed back effect of the contact lenses. Last year she drove 10,000 miles. She wears reading spectacles over her contact lenses. She has dryness issues and her daily wear is from 7.00am to 6.00pm. The low water content of these lenses 36% helps to stop them shrinking and increases her wearing time.  She uses re-wetting drops frequently.

The right lens locates perfectly. The left lens rotates fifteen degrees temporally and is stable.

She also suffers with slight hay fever but finds it much less severe when wearing the lenses. The photographs show a combined stain of Fluorescein with Lissamine Green. This patient occasionally has punctate epithelial stain due to dryness but none was present at the last aftercare.

Case Study Three: Silicone Hydrogel
Miss A (aged 28 years old) had been keen to try laser treatment but like her mother suffered from dry eyes and had been told by the laser clinic that her dryness was a contraindication.

She had tried all the newer Silicone hydrogel materials with the higher water content and a one size fit. The most that she had managed was one hour of wear. She had also tried daily disposables unsuccessfully, as they dehydrated.

She was very atopic and suffered with asthma, eczema and hay fever. She took a contraceptive pill for acne treatment and asthma inhalants. She had a full dry eye assessment with phenol red thread (RE 18mm, LE 12mm), tearscope, lipid layer imaging and non invasive break up time (RE 11.9 seconds, LE 10.9 seconds). She was asked to take a multi-vitamin and multi-mineral with 15mg of Zinc as she was vegetarian and may have been short of Zinc in her diet. The lipid layer was 50-80nm but the aqueous layer was poor. Lissamine green stain showed no mucous deficiency.

Contact Lens Fitting:

Silicone hydrogel:  Diameter 14.00 Base Curve 8.6

Power RE -2.00 V/A 6/6+3
Power LE -2.00 V/A 6/6+5

This patient now achieves weekly extended wear. She has a low water content lens that does not dehydrate with a flatter fitting than the 8.4’s she tried to wear previously. She uses a cleaner weekly and re-wetting drops four times a day. When asked about her vision she replied that it was “perfect”.