Department of optometry
College of applied medical sciences
King saud university
Opto 354
Name: …………… ID#………………..
Q.1 How to correct the following fitting to obtain the optimum one (if needed) ?
A) (Dia=14.00 \ mm BC=8.5 mm) Steep Fitting :
Decrease diameter (by 0.50 mm) OR Increase Base Curve (by 0.3 mm)
Dia=13.5 mm OR BC=8.8 mm
B) (Dia=14.00 mm \ mm BC= 9 mm) Flat fitting :
Increase diameter (by 0.50 mm) OR Decrease Base Curve (by 0.3 mm)
Dia=14.5 mm OR BC=8.6 mm
Q.2
A 21 year old girl wishes to wear contact lenses. Her prefitting clinical data are:
|
OS |
OD |
Parameter |
|
43.00\44.00@180 |
40.50\42.00@180 |
K`s |
|
12.50 mm |
12.50 mm |
HVID |
|
12 mm |
12 mm |
VVID |
|
4 mm |
4 mm |
Pupil D. |
|
- 2.50-1.00X180 |
- 4.50-0.25X180 |
Ref. |
Find the initial lenses OU for this girl .
OD
Dia= HVID+2mm= 12.50+2= 14.50 mm
BC=flatest K-reading-3D=40.50-3=37.5D= 9.00 mm
Power= -4.50 > -4.00 = Fs\Fs-1*(d*Fs) = -4.25 D
OS
Dia= HVID+2mm= 12.50+2= 14.50 mm
BC=43.00-3.00=40.00D= 8.4 mm
Power= Sph + 1\2 Cylinder = -2.50 + (- 0.50) = -3.00
initial lenses OU
OD 14.50mm \ 9.00mm \ - 4.25D
OS 14.50mm \ 8.4mm \ - 3.00D