rgp_lenses_flashcards
What are some reasons for fitting RGP lenses?
RGP lenses are fitted for reasons such as aphakia, corneas with high DC, keratoconus, post-graft surgery, and for better vision with high prescriptions.
Why are RGP lenses beneficial for patients with high prescriptions?
RGP lenses provide better vision with high prescriptions and are more durable, with wear times of up to 1 year.
What are the advantages of RGP lenses in terms of eye health?
RGP lenses offer high oxygen permeability, don’t dry out the tear film due to their 0% water content, and are resistant to protein deposits.
How is the total diameter (TD) of an RGP lens determined?
The total diameter (TD) is related to the horizontal visible iris diameter (HVID), typically HVID - 2mm.
What is BOZR in relation to RGP lenses, and how is it fitted?
BOZR refers to the base curve radius of the RGP lens and is usually fitted based on K-readings, with most lenses fitted to the flattest K.
What does BOZD refer to in RGP lenses?
BOZD is the diameter of the optic zone in RGP lenses and is related to the maximum pupil size.
What is an acceptable level of movement on blink (MOB) for RGP lenses?
An acceptable MOB for RGP lenses is 1-2mm with no limbal excursion.
What are the characteristics of Fluoro-Silicone Acrylates in RGP materials?
Fluoro-Silicone Acrylates have a Dk of 40-100, offer better wetting and less deposits, but are susceptible to lipids, mucus, scratching, and lens flexure.
What does HDS stand for, and how does it improve RGP lens performance?
HDS stands for Hyper-purified Delivery System. It removes inefficient silicone molecules, leading to higher oxygen permeability and improved surface wettability.
What is the Dk value of ML210 material for RGP lenses, and what are its benefits?
ML210 has a Dk value of 210. It offers high oxygen delivery and good resistance to protein deposits.
What are the characteristics of Boston EO material for RGP lenses?
Boston EO has a Dk of 58, offers excellent wetting and deposit resistance, and is made from Fluorosilicone Acrylate.
How does the design of RGP lenses relate to the aspheric nature of the cornea?
The cornea is aspheric, with central steeping and flattening towards the periphery, and RGP lenses are designed to fit this shape.
What happens if an RGP lens is fitted too steep?
If an RGP lens is fitted too steep, it leads to central pooling, minimal movement on blink, good centration, but potential air bubbles.
What happens if an RGP lens is fitted too flat?
If an RGP lens is fitted too flat, it results in central touch, excessive movement, discomfort, and unstable vision.
What is the main function of Poloxamine in Boston Simplus Multi-Action Solution?
Poloxamine removes lipids and environmental debris from the lens surface.
