STEP BY STEP SOFT CONTACT LENS FITTING
Ariesanti Tri Handayani
Dept of Ophthalmology, School of Medicine
Udayana University / Sanglah Hospital
Denpasar - Bali
IOA Bali - Alcon Seminars and Workshop, Prime Plaza Hotel, 30 March 2019
INDICATION
Refractive errors: Myopia; Hyperopia; Small amount of astigmatism (<1.00 D)
Therapeutic / Bandage: corneal erosion; bullous keratopathy;
chemical trauma, etc
Cosmetic / Prosthetic
SOFTLENS PARAMETERS
Base curve Diameter Power
Courtesy of AAO BSCS 2017, Clinical Optic
BASE CURVE (BC) OR BACK OPTIC ZONE RADIUS (BOZR)
The curvature of central posterior surface of the lens, which is adjacent to the cornea
Measured by its radius of curvature (mm) or may be converted to Diopters (D) by taking reciprocal of the radius
AAO: BC : 0.2 – 0.6 mm greater (flatter) than the radius of the flattest K reading
BC = Flattest K + 0,6 mm
BASE CURVE (BC) OR BACK OPTIC ZONE RADIUS (BOZR)
Keratometri:
K1 7.90 @ 180 K2 7.60 @ 90 Flattest K: 7.90
BC: 7.90 + 0,6 = 8.50 BC 8.50
DIAMETER (TD)
The width of the contact lens, which typically varies with the lens material
SCL diameter usually ranges from 13 to 15 mm
HVID = Horizontal Visible Iris Diameter = horizontal corneal diameter
Total Diameter (TD) = HVID + 2 mm
eg. HVID 12 mm TD = 12 + 2 mm = 14 mm
POWER (P) OR BACK VERTEX POWER (BVP)
As close as possible to patients refraction corrected by vertex distance
BVL CL = F spectacles/ 1- (Vertex Distance in meter x F spectacles)
eg. F Spectacles = -8.00 D; Vertex Distance (VD) = 12 mm BVP = -8.00 / 1-(0.012 m X– 8.00) = 7.33 D
Vertex Distance need to be adjust if the refraction more than 4.00 D use VD conversion table
EVALUATION OF SOFTLENS FIT
Adequate fit:
Centration
Movement
Patient’s vision & comfort
CENTRATION
Courtesy of IACLE
MOVEMENT
Good Fit: lens will move approximately 0.5 – 1 mm with upward gaze or blink or gentle pressure on lower eyelid to move the lens (push up test)
Tight fit lens do not move at all Loose fit lens move too much
PATIENT’S VISION AND COMFORT
Over refraction
Comfort: no tearing after several minutes, no foreign body sensation, no limbal injection
ADJUSTING SOFTLENS FIT
Courtesy of AAO BSCS 2017, Clinical Optic
Courtesy of AAO BSCS 2017, Clinical Optic
DISPENSING
Recommendation :
Patient education: signs of infections, dry eye, hypoxia, deposits
Types of lens wear: Daily Disposable; Daily Wear; Extended Wear
Replacement: 1 day/ 2 week/ monthly/ yearly
Lens care: solution; wetting; cleansing
Follow up: 24-48 hours after fitting ( for EW);1 week after fitting; 1- 6 months after use CL
PRESCRIPTION
Air Optix Aqua
8.
8.66 14.2
Courtesy of AAO BSCS 2017, Clinical Optic
