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EXAM opto354

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