5.3.3. Understands the techniques used in the fitting of complex contact lenses and advises patients requiring complex correctio Flashcards
What are the types of contact lenses available for aphakia and their fitting characteristics?
Conventional RGPs: Quasar SV (power range of +/-25.00D), Quasar Toric. Custom Made Soft Contact Lenses: Ultravision Aphakic & Myopic (+/-45.00D, base curvature of 7-9.8mm, TD of 12.5-16mm).
What options exist for astigmatic aphakia patients?
Ultravision Avanti for Astigmatism: Sph +/-20.00D, Cyl up to 8.00D, Axis in 1-degree steps, Add +4.00, Base Curvature: 8-9.2mm, Total Diameter: 14-15mm.
How do therapeutic contact lenses benefit post-surgery patients?
Therapeutic lenses provide comfort and protection by acting as bandage lenses to reduce mechanical trauma. Used post-LASEK, post-lamellar graft, corneal erosions.
What are hybrid contact lenses, and why are they useful for patients with astigmatism or irregular corneas?
Hybrid lenses have an RGP center and soft lens skirt. Useful for patients who can’t tolerate RGPs but need better vision, or have irregular corneas due to grafts or keratoconus.
What are the characteristics of the UltraHealth SynergEyes lens?
UltraHealth SynergEyes combines RGP center with soft SiHy skirt. TD 14.5mm, Dk 130 for rigid portion, 84 for soft portion. High stability for astigmatic patients.
What are the signs and symptoms of keratoconus, and how is it diagnosed?
Symptoms: Frequent Rx changes, myopia, astigmatism, blurred vision, glare. Diagnosis: Scissor Reflex, Oil Droplet Reflex, Steep K readings, Vogt Striae, Fleischer Ring.
What are Vogt Striae and Fleischer Ring in keratoconus?
Vogt Striae: Vertical stromal stress lines, disappear with globe pressure. Fleischer Ring: Epithelial iron deposits around the cone base, best seen under cobalt blue.
How are custom-made soft contact lenses used to treat keratoconus?
Ultravision Keratosoft, designed for mild keratoconus, SiHy material, available in disposable or 3/6/9 monthly, TD: 14-15mm.
What are the fitting principles for RGPs in keratoconus?
RGPs (e.g., Menicon Rose K, Quasar K) are fitted for minimal apical touch and clearance, achieving three-point touch with mid-peripheral support.
What is the purpose and limitation of using a piggyback system in keratoconus management?
Piggyback system: RGP worn over a soft lens for comfort and stability. Limitation: Two lenses reduce oxygen transmission to the cornea.
How does a scleral lens work, and what conditions is it used for?
Scleral lenses are large diameter RGPs (up to 25mm) that vault over the cornea with a tear-filled reservoir. Used for advanced keratoconus, post-surgical corneas, dry eye.
How does a mini-scleral lens differ from a scleral lens, and what is it used for?
Mini-scleral lenses are smaller than full sclerals but larger than RGPs. Used for post-surgery, corneal scarring, irregularity, dry eyes. Commonly used: B&L Zen lenses.
What are the fitting considerations for mini-scleral lenses, and what should be assessed?
Fit should vault the cornea. Assess central clearance (300-400 microns), limbal clearance, and scleral landing to avoid vessel impingement.
How are mini-scleral lenses inserted and removed?
Inserted by filling lens with non-preserved saline, placed directly on the eye. Removed using scissor technique or by inducing an air bubble.
What care regime should be followed for scleral lenses?
Care regime includes soft lens solutions (not GP), non-preserved saline, alcohol-based cleaner. Avoid air-drying the lens case.
