I N D U C E D P R I S M AT I C E F F E C T S D U E TO P O O R LY F I T T E D S P E C TA C L E Optom. ANJALI AHUJA¹, Optom. USMAN MEMON²
NAGAR SCHOOL OF OPTOMETRY¹²
0 1 I N T R O D U C T I O N
L o o k i n g a t t h e c u r r e n t s c e n a r i o o f m a r ke t t h e n o r m s
f o r m i n i m u m s t a n d a r d s f o r o p t i c a l d i s p e n s i n g p ra c -
t i c e a r e n o t b e i n g f o l l o w e d , t h e r e f o r e c u r r e n t s t u d y
w a s u n d e r t a ke n , t o u n d e r s t a n d t h e i m p o r t a n c e o f
f i t t i n g a s p e c t s o f s p e c t a c l e s w i t h r e s p e c t t o t h e i n -
t e r p u p i l l a r y d i s t a n c e , i n s p e c t a c l e w e a r e r s w i t h n o
c o m p l a i n t s .
0 2 A I M S A N D O B J E C T I V E S
To s t u d y t h e p r e v a l e n c e a n d u n d e r s t a n d t h e a s s o c i a t e d p r i s m a t i c e f f e c t s o f
p o o r l y f i t t e d s p e c t a c l e i n a s y m p t o m a t i c w e a r e r s .
To d e t e r m i n e t h e p e r c e n t a g e o f i n d u c e d h o r i z o n t a l a n d v e r t i c a l p r i s m a t i c e f f e c t s
a c c o r d i n g t o A N S I t o l e ra n c e Z 8 0 . 1 - 2 0 1 0 i n s i n g l e v i s i o n s p e c t a c l e w e a r e r s , w h o
w e r e u s i n g d e c e n t e r e d l e n s e s .
0 3 M E T H O D O LO G Y
Fo l l o w i n g s t e p w i s e p r o c e d u r e wa s f o l l o w e d f o r e a c h a n d e v e r y i n d i v i d ua l : - T h e I n t e r p u p i l l a r y d i s t a n c e w a s m e a s u r e d w i t h t h e h e l p o f P u p i l l o m e t e r
O p t i c a l c e n t e r s w e r e m a r k e d w i t h b l a c k m a r k e r a n d p o w e r w a s m e a s u r e d u s i n g L e n s o m e t e r
T h e c o - r e l a t i o n b e t w e e n f r a m e c e n t r a t i o n w i t h r e s p e c t t o P D w a s t a k e n i n t o c o n s i d e r a t i o n
T h e d i s t a n c e b e t w e e n f r a m e m a r k i n g s w e r e m e a s u r e d t o d e t e r m i n e t h e c e n t r a t i o n d i s t a n c e & w e r e
c o m p a r e d t o d i s t a n c e P D
O b l i q u e c y l i n d e r s w e r e r e s o l v e d i n t o h o r i z o n t a l a n d v e r t i c a l c o m p o n e n t s
A n y p r i s m a t i c e f f e c t p r e s e n t w e r e t h e r e a f t e r c a l c u l a t e d u s i n g P r e n t i c e ’ s r u l e & r e c o r d e d
1 . A t e x t b o o k o f O p t i c s S . C H A N D , N . S U B R A M A N Y A M B R I J L A L , M . N . A V A B H A N U L U . C h a p t e r 4 ( P a g e N o . 7 2 ) . w w w . p r e n t i c e i m a g e . c o m
2 . C l i n i c a l O p t i c s , S e c o n d E d i t i o n , T r o y E F e n n i n , O . D . T h e o d o r e G r o s v e n o r , O . D . C h a p t e r 4 ( P a g e N o . 8 5 , 8 6 , 9 5 , 9 6 , 9 7 , 9 8 ) .
3 . S y s t e m f o r O p h t h a l m i c d i s p e n s i n g , S e c o n d E d i t i o n , C l i f f o r d W . B r o o k , O . D . I r v i n M . B o r i s h , C h a p t e r 3 , 5 , 1 5 , 1 6 , 1 8 ( P a g e N o 2 6 , 2 7 , 4 2 5 , 4 2 7 , 4 3 4 ) .
4 . T e a c h e r s E y e C a r e . P r o p e r C a r e o f Y o u r S p e c t a c l e s .
5 . A v a i l a b l e f r o m : h t t p s : / / w w w . t e a c h e r s e y e c a r e . c o m . a u / n b s p n b s p p r o d u c t / P r o p e r C a r e o f y o u r s p e c t a c l e / t a b i d / 6 2 / D e f a u l t . a s p x ( A c c e s s e d o n t h e 0 2 / 0 9 / 2 0 1 0 ) .
6 . B r o o k s C W , B o r i s h I M . S y s t e m f o r O p h t h a l m i c d i s p e n s i n g . N e w Y o r k : P r o f e s s i o n a l P r e s s , 1 9 7 9 p p 2 7 - 6 5 .
7 . V R M o o d l e y , F K a d w a , B N x u m a l o , S P e n c e l i a h , B R a m k a l a m , A Z a m a . I n d u c e d p r i s m a t i c e f f e c t d u e t o p o o r l y f i t t i n g s p e c t a c l e f r a m e s .
8 . S A i r O p t o m 2 0 1 1 7 0 ( 4 ) 1 6 8 - 1 7 4 . I S S N 0 3 7 8 - 9 4 1 1 .
9 . F o w l e r C , L a t h a m P e t r e K . S p e c t a c l e l e n s e s : T h e o r y a n d p r a c t i c e . B u t t e r w o r t h - H e i n e m a n n O x f o r d 2 0 0 1 p p 3 7 - 5 1 .
1 0 . O s u o b e n i E P , A l - F a h d i M . D i f f e r e n c e s b e t w e e n a n a t o m i c a l a n d p h y s i o l o g i c a l i n t e r p u p i l l a r y d i s t a n c e . J A m O p t o m A s - s o c 1 9 9 4 6 5 2 6 5 - 7 1 .
1 1 . G r i f f i n J R , G r i s h a m J D , B i n o c u l a r a n o m a l i e s d i a g n o s i s a n d v i s i o n t h e r a p y , 4 t h e d . B u t t e r w o r t h H e i n e m a n n 2 0 0 2 ( P a g e n o 9 2 . ) .
1 2 . F e r n a n d e z - R u i z J . , D i a z R . P r i s m a d a p t a t i o n a n d a f t e r e f f e c t : s p e c i f y i n g t h e p r o p e r t i e s o f a p r o c e d u r a l m e m o r y s y s t e m . L e a r n M e m 1 9 9 9 6 ( 1 ) ( p g s . 4 7 - 5 3 ) .
1 3 . H e n s o n D B , N o r t h R . A d a p t a t i o n t o p r i s m i n d u c e d h e t e r o p h o r i a . A m J O p t o m P h y s i o l O p t 1 9 8 0 5 7 1 2 7 - 1 3 7 .
1 4 . D u T o i t R , R a m k e J , B r i a n G . T o l e r a n c e t o p r i s m i n d u c e d b y r e a d y m a d e s p e c t a c l e s : s e t t i n g a n d u s i n g s t a n d a r d . A m J O p t o m 2 0 0 7 8 4 ( 1 1 ) 1 0 5 3 - 9 .
1 5 . T o p l i s s W S . O p t i c a l d i s p e n s i n g a n d w o r k s h o p p r a c t i c e . B u t t e r w o r t h L o n d o n , 1 9 7 5 p p 4 2 - 5 9 . 1 6 . J a l i e M . T h e p r i n c i p l e s o f o p h t h a l m i c l e n s e s . 4 t h e d . T h e A s s o c i a t i o n o f B r i t i s h D i s p e n s i n g O p t i c i a n s L o n d o n 1 9 9 2 .
T h o u g h a l l t h e a s y m p t o m a t i c s u b j e c t s w e r e n o t l o o k i n g t h r o u g h t h e o p t i c a l c e n t e r o f t h e i r s p e c t a c l e s a r e
b e n e f i t t e d d u e t o p r o b a b l e p r i s m a d a p t a t i o n i n l o w e r p r e s c r i p t i o n s .
A s c u r r e n t s c e n a r i o d e m a n d s m o r e o f n e a r a n d i n t e r m e d i a t e w o r k p r o f i l e f o r l o n g e r d u ra t i o n , i t i s o f u t -
m o s t i m p o r t a n c e t h a t p u p i l l a r y d i s t a n c e s h o u l d c o i n c i d e w i t h o p t i c a l c e n t e r s o f t h e s p e c t a c l e i n c a s e o f
e v e r y i n d i v i d u a l s f o r z e r o o r l e a s t p r i s m a t i c e f f e c t . But if some prismatic effect still persist, it can be adapted.
INCLUSION CRITERIA
EXCLUSION CRITERIA
Asymptomatic single vision spectacle wearers
Bifocal wearers
Multifocal wearers
Strabismic Individuals
•As per ANSI tolerance, study subjects were divided in 2 groups :-
For power ≤ ±2.75D in
horizontal meridian
For power ≥ ±2.75 D In
horizontal meridian
Unwanted horizontal prism for both
eyes combined shall not be greater
than 0.67 ∆.
Horizontal difference from ordered
PD and Actual PD measured, dis-
tance between the PRP shall not be
greater than 2.5mm.
For power ≤±3.375D in
vertical meridian
For power ≥ ±3.375 D in
vertical meridian
Unwanted vertical imbalance shall not exceed 0.33 ∆.
Vertical difference between the PRP shall not be greater than 1mm.
S T U DY F I N D I N G S : -
Out of 100, there were 58 female subjects.
Horizontal Prismatic effect for lenses of power ≤ ±2.75D was effec-
tive in right eye of 47% subjects with effect of 1.31 ±0.91∆D left
eye of 43% subjects were with effect of 1.27 ±0.90∆D.
Horizontal Prismatic effect for lenses of power ≥ ±2.75D was effec-
tive in 17% with effect of 3.28 ±1.78∆D in right eye and 25% with
effect of 3.52 ±1.44∆D in left eye in the horizontal meridian .
Vertical Prismatic effect was effective in right eye of 30% subjects
with effect of 0.20 ±0.47∆D and in left eye of 34% subjects noticed
the prismatic effect of 0.24 ±0.51∆D for lenses of power ≤ ±3.375∆D.
And for lenses of power ≥ ±3.375∆D, in right eye 13% noticed
vertical differences between PRP was greater than 1 mm with
1.72 ±1.47∆D in vertical meridian and in left eye, 14% subjects
noticed vertical differences between PRP was greater than 1 mm
with 1.85 ±1.69∆D in vertical meridian.
0 6 R E F E R E N C E S
0 4 R E S U LT S
0 5 D I S C U S S I O N
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