RGP contact lens fitting

This ppt is based in the topic of contact lens fitting of the RGP type contact lens. this is one of my university assignment. i am currently the student of centurion university of technology and management located in odisha.

1. RGP contact lens fitting Name :-Satyam Goit Branch :-BSc optometry(4 th sem ) Red.no :- 211704150018 Subject :- Contact lens 1

2.   What is RGP lens ?? RGP lenses are those lenses made up of materials which are permeable to oxygen Due to their oxygen permeability they have become popular by the name semisoft lenses

3. Are RGP lenses better than soft lens?? Good vision Durability Able to correct astigmatism completely most of the cases Excellent eye health Less tendency of deposit formation Ease of care & maintenance Cost factor

4. Choice for RGP/ Indications Keratoconus High refractive error & high astigmatism Trauma or irregular astigmatism Post graft Slow down myopia progression Corneal degenerations & dystrophies Applied in orthokeratology

5. RGP FITTING PATIENT SCREENING PRELIMINARY EXAMINATION & MEASUREMENTS TRIAL LENS FITTING LENS DISPENSING AFTER CARE RGP FITTING PATIENT SCREENING PRELIMINARY EXAMINATION & MEASUREMENTS TRIAL LENS FITTING LENS DISPENSING AFTER CARE

6. Patient Screening   Establish why the patient wants CLs Is the patient suitable for RGP Obtaining baseline information Advise patient of their options

7. Preliminary measures Corneal radius of curvature Corneal topography is essential for selecting the BOZR Measurement is usually made with keratometry Average k or flat k reading is taken as trial lens BOZR

8. Corneal Diameter  Guide to the total lens diameter Measuring Horizontal Visible Iris Diameter (HVID) by using millimeter ruler Total lens diameter will be 2.3 to 2.5 mm less than HVID Pupil Size For the selection of BOZD ( Back Optic Zone Diameter) BOZD is about 1mm larger than the pupil diameter in dim illumination

9. TRIAL LENS SELECTION & FITTING Range Of Designs Required For low & high minus: the recommended BVP (back vertex power) is -3.00 D for low minus & -6.00 D for high minus For low & high plus: +2.00 D for low & +5.00 D for high plus Diameter: for each BVP, it is valuable to have two diameter, a small dia of 9.20mm & large dia of 9.60mm BOZR: range of base curve is required from 7.00 mm to 8.40 mm (0.05 mm step)

10. Lens Application Patient Instructions Counsel the patient on the sensation they will notice when the lens is placed on the cornea Advise to keep eyes closed for few seconds after the lens placed on the cornea Setting time An adequate amount of time must be given Excessive tearing results in an inaccurate fitting assessment

11. Dynamic Fitting Assessment Centration Examine the lens location on the cornea High riding or low riding Excessive decentration may cause visual problems, lens instability LOW RIDING HIGH RIDING CENTERED Stability Does the lens have consistent movement & position of rest or decentration Assessed after adequate degree of adaptation has been achieved

12. Movement Amount of movement Assessed by post blink recentration of the lens The post blink movement may be as much as 1 to 1.5 mm Type of movement Smooth vertical movement Apical rotation Rocky movement Two part movement lid attachment Speed of movement Rate as slow , average or fast

13. Static Fitting Assessment Determine the relationship b/w the lens back surface & the anterior surface of cornea Assessed with the patient instructed to looking in the primary gaze position, lens should be centered on the cornea or its natural resting position With the lens centered, the fluorescein pattern is assessed & recorded Static Fitting Techniques Central zone Central Pooling – steep fit Alignment- ideal fit Central touch- flat fit