Assalamualaikum and Very Afternoon to all readers,

For 2nd year students, do you still remember the rule how to determine Prismatic Effect (base up, down, in out) that I've been taught in class last week. InsyaAllah, I'll share it the rule using video post with all of the readers in next time.

How to calculate the prismatic effect amount induced by decentration??? The formula is very simple.

P (prism power)=c (decentration, in cm,

**not in mm)**x F (focal power, D)Simple, right...most of us have difficulty to determine which base will be induced by the decentration (c- in, out, up, down) and focal power (F- plus, minus)...by using my rule, InsyaAllah it will be easier to determine it. As I said before, the video is under construction but I've explain it in 2nd year class..Thus, in this post I would to give a tutorial to all 2nd year regarding this topic.

Question: Calculate prismatic effect if the decentration and focal power as follow;

- c=2mm in F=-3.00D
- c=2mm in F=+3.00D
- c=2cm out F=-13.00D
- c=4mm up F=-3.00D
- c=7mm out F=-12.00D
- c=2mm in F=+12.50D

- c=3cm in F=-0.250D
- c=2mm down F=-2.00D
- c=2mm down F=-31.00D
- c=8mm up F=+3.75D

- c=4mm downF=-3.00D /-2.00x 180
- c=6mm in F=-3.00D/-1.00x 90
- c=21mm out F=+3.00D/+2.00X180
- c=8mm up F=-3.00D /+4.00@90

- c=8mm out F=-3.00D/+4.00X90
- c=9mm in F=-3.00D/-9.00@90
- c=1mm down F=-13.00D/+2.000X90
- c=1.5mm in F=+23.00D/-2.75X180

- c=9mm up F=-7.00D
- c=8mm up F=-8.00D
- c=3mm out F=-9.00D
- c=1.2mm up F=+5.00D/+5.00x90

Deadline is this Sunday 13/ February/2011

no 3

ReplyDeletec: 2cm out

F: -13D

P=cF

P=2cm x -13D

P= 26 Prism Diopter Base In

no 1

ReplyDeletec=2mm in F=-3.00D

P = cF

P = (0.2cm) x (-3D)

= 0.6 Prism Diopter Base out

no 2

ReplyDeletec=2mm in F=+3.00D

P=cF

P= (0.2cm) x (+3.00D)

= 0.6 Prism Diopter Base In

19)

ReplyDeletec:9mm (0.9cm)

base-up

F:-7.00D

P=cF

=(0.9cm)(-7.00D)

=6.3 Prism Diopter Base-Down

no.6

ReplyDeletec= 2mm in

F= +12.50D

P=cF

= 0.2cm X +12.50D

= 2.5D base in

@raja nor shahila raja mohamad

ReplyDeletecorrection:

P= cF

= 0.2cm X +12.50D

=2.5 Prism Diopter Base In

salam..

ReplyDeletequestion 21:

P = cF

P = (0.3cm)x (-9D)

P = 2.7 prism diopter base in

no. 9

ReplyDeletec=2mm down F=-31.00D

P = cF

P = (0.2cm)x (-31.00D)

P = 6.2 Prism Diopter base up

q20

ReplyDeletec= 8 mm (0.8cm)

F= -8.00 DS

P=cF

= (0.8) (-8.00)

= 6.4 base down

Question #7

ReplyDeletec= 3cm

F= -0.25DS

Answer;

P = cF

P = 3cm x -0.25DS

P = 0.75 base out

P=cF

ReplyDeleteP= (4mm/10) x 3

P= 1.2pd base down

@nur amalina zulkefli

ReplyDeletequestion numb 4

no 5

ReplyDeletec= 7mm out (0.7cm)

F= -12.00 D

P=cF

P= (0.7 cm)(-12.00 D)

= 8.4 prism diopter base in

Question #8

ReplyDeletec= 2mm

F= -2.00DS

Answer;

P = cF

P = 0.2cm x -2.00DS

P = 0.40 base up

@Kisah Seorang Penchenta

ReplyDeleteQuestion #8

c= 2mm

F= -2.00DS

Answer;

P = cF

P = 0.2cm x -2.00DS

P = 0.40 prism diopter base up

@Mimie Halil

ReplyDeleteQuestion #7

c= 3cm

F= -0.25DS

Answer;

P = cF

P = 3cm x -0.25DS

P = 0.75 prism diopter base out

Q10.

ReplyDeletec= 0.8cm

F= +3.75 D

P= cF

= (0.8) x (+3.75)

= 3 prism diopter base up

Q 15:

ReplyDeletec =8mm out

F=-3.00D/+4.00X90

@ vertical : -3.00 DS

@ horizontal: + 1.00 DS

c = 0.8 cm

1) @ vertical meridian:

P = cF

P = 0.8 cm x -3.00 DS

= 2.4 prism diopter base in

2) @ horizontal meridian:

P = cF

P = 0.8 cm x +1.00 DS

= 0.8 prism diopter base out

Q 11:

ReplyDeletec =4mm down

F=-3.00DS/-2.00 DCX 180

@ vertical : -5.00 DS

@ horizontal: -3.00 DS

c = 0.4 cm

1) @ vertical meridian:

P = cF

P = 0.4 cm x -5.00 DS

= 2.0 prism diopter base up

2) @ horizontal meridian:

P = cF

P = 0.4 cm x -3.00 DS

= 1.2 prism diopter base up

Soalan 13

ReplyDeletec=21mm out F=+3.00D/+2.00X180

Transpose...F=+5.00D/-2.00X90

+5.00D @90

+3.00D @180

c= 2.1cm

P=cF

At vertical meridian:

P=(2.1)(+5.00)

=10.5prism diopter base out

At Horizontal meridian:

P=(2.1)(+3.00)

=6.3prism diopter base out

Question 17

ReplyDeletec= 1 mm down

F= -13.00DS/ +2.00DC x 90

transpose = -11.00DS/ -2.00DC x 180

c= 0.1 cm

@ vertical= -13.00DS

@horizontal = -11.00 DS

a) @ vertical:

P= cF

=(0.1 cm )(-13.00DS)

= 1.3 prism diopter base up

b) @ horizontal :

P=cF

= (0.1 cm ) ( -11.00DS)

= 1.1 prism diopter base up

salam..

ReplyDeletemy answer for question no.22

C=1.2mm up

F= +5.00D/ +5.00X90

transpose: +10.00D/-5.00X180

c=0.12cm

@vertical=+5.00DS

@horizontal=+10.00DS

a) @vertical

P=cF

P=(0.12cm)(+5.00DS)

P=0.6 prism diopter base UP

b) @horizontal

P=cF

P=(0.12cm)(+10.00DS)

P=1.2 prism diopter base UP

Q 12:

ReplyDeletec =6mm in

F=-3.00DS/-1.00 DC X 90

@ vertical : -3.00 DS

@ horizontal: -4.00 DS

c = 0.6 cm

1) @ vertical meridian:

P = cF

P = 0.6 cm x -3.00 DS

= 1.8 prism diopter base out

2) @ horizontal meridian:

P = cF

P = 0.6 cm x -4.00 DS

= 2.4 prism diopter base out

Q16:

ReplyDeletec = 9mm(0.9cm) in

F = -3.00DS/-9.00DC @ 90

P = cF

@ horizontal meridian

F = -3.00D

c = 0.9cm in

P = cF

P = (0.9) x 3.00

P = 2.70 Prism Diopter BO

@ vertical meridian

F = -12.00D

c= 0.9cm in

P = cF

P = (0.9) x 12.00

P = 10.80 Prism Diopter BO

correction:

ReplyDeleteq20

c= 8 mm (0.8cm)

F= -8.00 DS

P=cF

= (0.8) (-8.00)

= 6.4 prism diopter base down

q14 :c=8mm up F=-3.00D /+4.00@90

ReplyDelete@ horizontal meridian

F = -3.00D

c = 0.8cm

P = cF

P = (0.8) x 3.00

P = 2.40 Prism Diopter BD

@ vertical meridian

F = +1.00D

c= 0.8cm in

P = cF

P = (0.8) x 1.00

P = 0.80 Prism Diopter BU

sbgai salh seorang budk optometri...nampk macm menarik jer blog nie,,,bole join????huhuuu...

ReplyDeletecan some plz help me need some help with dencentaion and PE

ReplyDeleteGUYS PLS HELP, HAVE TO SUBMIT MY COURSWORKBY TOMORROW.

ReplyDeleteBASICALLY MY DECENTRATION VALUE IS 70MM BUT HOW DO YOU DETERMINE ITS DIRECTION?( IN , OUT, UP, DOWN)

PLS REPLY TO junaidk595@gmail.com

Guys plz help me calculate pe of apoint 6mm below and 4mm inwards from optical center of alens +3.00/-3.00x120

ReplyDelete