guide to prescribing glasses

1. GLASS PRESCRIPTION
AMONG YOUNGS AND
EDUCATE ELDERLY ABOUT
PROGRESSIVE LENSES
DR. AMARENDRA KUMAR
M.S

2. WHY WE PRESCRIBE GLASSES
 Majority of patients in our opd comes with complaints of
VISUAL SYMPTOMS
OCULAR SYMPTOMS
REFFERED
SYMPTOMS
• BLURRED VISSION
• DIPLOPIA
• CONFUSION
• HEADACHE
• ASTHENOPIA
• EYE STRAIN
• OCULAR
IRRITATION
• PAIN
• In child
intractable
blepharitis and
conjunctivitis

3. GLASS PRESCRIPTION
HYPEROPIA Age
Fogging
Refinement methods
1. Less than 3yrs ------- Full Correction
2. 3 to 8yrs -------------- depends on tropia or phoria
3. Adults to follow rule of strongest+
 MYOPIA
1. Thumb rules
Full Gross Value
subjective to
AC/A
Full net---
optimal,
undercorrecti
on
Normal Patients
• -1to -6 full correction
• >-6 undercorrect
Esotropia
• -6 DS or Above
under correct to
optimal
Exotropia
• Over correct
in intmittent
Exotropia

4. GLASS PRESCRIPTION
 ASTIGMATISM
Normal Patients
: In child less than 3 yrs of age = 1.25DS regular
: Older than 3 yrs. = all astigmatism should be corrected
 Child and young : followed up 6 monthly
 Adults : 6 month to yearly
 Frequent changes : over correct (0.25D)
 Every patients suspected of refractive error should be checkeked Dry and Wet AR
 For >5yrs Tropicacyl Plus every 10 min upto 30 min AR rechecked after 40 to 60 min
 For 3-5 yrs Atropine sulphate ointment tds for 3days AR rechecked after 3days
 Cyclopentolate may be other option in little childs

5. RELATIONSHIP BETWEEN VISUAL
ACUITY AND REFRACTIVE ERROR
Snellens Visual Acuity Uncorrected Spherical
Errors(DS)
Uncorrected Cylindrical
Error(DC)
6/6 <=0.25 <=0.25
6/9 0.50 1.0
6/12 0.75 1.5
6/18 1.0 2.0
6/24 1.5 3.0
6/36 2.0 4.0
6/60 2.0-3.0 >=5.0

6. SOME COMMON DIFFERENCES
BETWEEN ADULTS AND CHILDREN
CHILDREN < 5YRS ADULTS
* Give refraction on axis as refracted * Give cyl close to 90 or 180 degree
* Full hyperopic cycloplegic refraction
tolerated well if less than age 5yrs
* Maximum tolerated plus even in
refractive accommodative esotropia
* Subjective manifest refraction less
important
* Subjective manifest refraction important

7. SOME COMMON DIFFERENCES
BETWEEN ADULTS AND CHILDREN
CHILDREN < 5YRS ADULTS
* Tolerate anisometropia; give full
regardless of age, strabismus, amblyopia
* Tolerate anisometropia poorly
* < 12yrs non wearing or wearing wrong
prescription will affect eye health
* Non wearing or wearing wrong
prescription have only minor temporary
consequences
# amblyopia, deviation, loss binocularity # asthenopia, red eye, dry eye

8. SOME COMMON DIFFERENCES
BETWEEN ADULTS AND CHILDREN
CHILDREN < 5YRS ADULTS
* Tolerate aneisokonia better but also
considered an implement to fusion and has
amblyopia potential
* Tolerate aneisokonia poorly
* Anisometric Rx, Aneisokonic spectacle Rx
has a role especially in patients requiring
occlusion
* Will not wear Rx that has a large
difference in refraction between the 2
eyes(threshold ? Different from patient to
patient)

9. SOME EXAMPLES
 We prescribe Spherical power on the basis of Wet AR
 Cylindrical power on the basis of dry AR
 For AR under TP we reduce 0.75
3yrs old boy with dry AR
RE +5.0 DS +1.0 DC@142
LE +6.0 DS+ 0.75 DC@71
wet AR RE +4.75 DS + 0.75 DC@152
LE +6.25 DS + 0.50 DC@69
Patient with phoria
Prescribed glass
RE +4.0 DS +0.5 DC@140
LE +5.0DS +0.25DC @ 70
5Yrs Boy with Amblyopia Dry AR
RE +0.25 DS + 0.50DC @137 v 6/6
LE +5.25DS + 0.75DC @54 v 6/36
Prescribed Glass
RE Plane v 6/6
LE +3.50DS v 6/18 with proper occlusion and
followup

10. CONTD.
 High refractive errors
12 Yrs old girl with dry AR
RE -5.25 DS -0.25 DC@37 v 3/60
LE -4.75DS -1.50 DC@157 v 3/60
Wet AR RE -5.0DS -0.50DC@38
LE -4.25DS -1.50DC@151
Prescribed glass
RE -4.75 DS v 6/6
LE -4.50DS -0.50DC @160 v 6/9
18yrs old boy with dry AR
RE -0.25DS -4.75 DC@6 v 3/60
LE -0.50DS -4.0DC@177 v3/60
Wet AR RE +0.25DS -4.75DC@4
LE +0.25DS-4.0DC@177
Prescribed glass
RE -3.75 DC@5 v 6/9
LE -3.25DC@180v 6/9

11. CONTD.
 Small errors with eye strain
15 yrs boy with Dry AR
RE +1.0 DS +0.25 DC@88 v 6/6p
LE +1.25 DS +0.50 DC@104 v 6/6 p
Wet AR RE +3.5DS +0.75DC@70
LE +3.25DS +0.50DC@100
Prescribed glass
RE +2.0DS V 6/6
+1.75DS v 6/6p
(Full +latent Hyper )
19yrs girl with Dry AR
RE -0.75 DC@87 v 6/6 p
LE -0.75DC@92 v 6/6p
Wet AR RE +0.75 DC@177
LE +0.75 DC@184
Prescribed glass
RE -0.50DC@90 v 6/6
LE -0.50 DC@90 v 6/6
(transposition)
20 yrs boy with Dry AR
RE +0.50DS +0.50DC@93 v 6/9
LE +0.5 DS+0.75DC@95 v6/9p
Wet AR RE +1.5DS +0.50 DC@88 LE
+1.50DS +0.75DC@93
Prescribed glass
RE +0.75DS +0.50DC@90 v 6/6
LE +0.75 DS +0.75DC@90 v 6/6

12. PROGRESSIVE ADDITION LENSES
 When the near point has receded beyond the distance at which the individual is accustomed to read or
to work is known as presbyopia in Latin old man’s eyes.
 Decrease in amplitude of accommodation with age
 Increase in near point of accommodation with age
 Progressive spectacle lenses, also called progressive addition lenses (PAL),progressive power
lenses, graduated prescription lenses, and varifocal or multifocal lenses, are corrective lenses used
in eyeglasses to correct presbyopia and other disorders of accommodation.
 Progressive lenses more closely mimic the natural vision that you enjoyed before the onset
of presbyopia. Instead of providing just two lens powers like bifocals (or three, like trifocals), progressive
lenses are true "multifocal" lenses that provide a smooth, seamless progression of many lens powers for
clear vision across the room, up close and at all distances in between.
Age in yrs Distance in cm Amplitude of accommodation(D)
10 7 14
20 10 10
30 14 7
40 20 3
50 40 2

13. PROGRESSIVE LENS (NO-LINE BIFOCAL)
VS.
LINE BIFOCAL
 Advantages
 No sudden “image jump” from distance to near.
 An infinite number of focal points to view objects at different distances.
 No visible line where the bifocal power begins.
 More natural vision for near viewing.
 A variety of lens designs to fit virtually any application.
 Disadvantages
 Requires a short period of adaptation to progressive lens for first-time wearers.
 Peripheral Distortion: Progressive lenses suffer the disadvantage of the power progression
creating regions of astigmatic aberration away from the optic axis, yielding poor
visual resolution.
 Costs more than a regular bifocal.

14. CONTD.
 Useful for long Computer user also protect from computer vision syndrome
 Can be prescribe comfortably to myopic with presbiopia
 Better lens materials. Today's progressive lenses are available in all the latest
lens materials, making them thinner, lighter and more comfortable than ever
before. Progressives made of high-index plastic lens materials can be up to 50
percent thinner than standard plastic bifocals.
 Today, many progressive lenses have compact designs specially made for
smaller eyeglass frames. With these new designs, wearers with small faces or
anyone who wants a smaller, fashionable frame can enjoy all the benefits of
progressive lenses.