Prescribing for refractive errors - presentation at www.eyenirvaan.com

1. PRESCRIBING FOR
REFRACTIVE
ERRORS
Mithali Kamat-Paranjape M. Optom
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3. Myopia

4. Simple Myopia
Usually
increases as age
increases till
adulthood !
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5. Myopia
• Optimal correction
• First time wearer: slight undercorrection may be
necessary
• Duochrome test is important
• If large lag of accommodation is noticed- slight
under correction
• Check comfort for near vision
• Exophoric patients benefit from spectacles than
CL
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6. Myopia
• Some myopes more comfortable reading
without the distance Rx
• Prescribing multifocals/progressives for
myopes:
– Ease of changing from distance to near focus
(depending on accommodation/convergence
relationship)
– Myopia control

7. Pseudomyopia
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8. Pseudomyopia
• Over stimulation of parasympathetic nervous
system
– Ocular fatigue during exams or change in work
schedule
– Active ocular inflammations like uveitis
• Diseased like
– Uncontrolled type 2 diabetes
– Myasthenia gravis
• Medicines that can cause pseudomyopia include:
– Hydralazine hydrochloride.
– Phenothiazines. These are antipsychotics,
tranquillizers, and drugs to reduce nausea.
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9. Myopia
1. Blur distance vision
2. Consistent vision
3. Usually no headache
4. Consistent retinoscopy
5. Mid-dilated pupils
6. Exophoric tendency
7. Similar manifestation on
cycloplegic refraction
Pseudomyopia
1. Blur distance vision
2. Fluctuating vision
3. Headache & asthenopia,
aggravated on near work
4. Fluctuating retinoscopy
5. Miotic pupils
6. Esophoric tendency
7. Very different manifestation
on cycloplegic refraction
8. Psychogenic factors usually
present
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10. Management
• Cycloplegic refraction
• If tendency for accommodative spasm
– Cycloplegic drops
– Plus over refraction
– Bifocal spectacles
• Exercises to increase the
accommodative facility and amplitude.
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11. Exercise to increase the
Accommodative Facility
• Push up exercises
• Brock String
• Flippers
• Hart Charts

12. Hypermetropia
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13. Hypermetropia
• Cycloplegic refraction is
a must
• Deduct for the tone of
the cilliary muscles
• Optimal correction or
slight overcorrection in
case of accommodative
esotropia

14. Hypermetropia
Age: upto 7 yrs
• No correction required if
– Error is small
– VA & binocular vision is normal
– Asymptomatic patient
– No anomalies of muscle imbalance
• If error is more than 1.50D, correct to avoide
strabismus
• Be careful while undercorrecting
• Monitor every 6 months
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15. Hypermetropia
Age: 8 yrs and above
• Full correction advisable, but
slight under correction
acceptable
• After 35, full correction
necessary
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16. Astigmatism
Up to 0.75D Low
1.00 to 1.50D Moderate
Above 1.50D High
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17. Astigmatism
First time Astigmat
• Adult
– Try optimal correction
– Undercorrection is acceptable,
maintaining the spherical
equivalent
– Rotate axis towards 90 and 180
– Check binocular vision
– Adjust one or both of the axis to
be parallel
– In-clinic trials
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18. Astigmatism
First time Astigmat: Child
• Optimal correction
• Yearly monitoring
ATR→WTR→ATR
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19. Astigmatism
Already using astigmatic correction but
change in
• Power
– See patients comfort.
– May require undercorrection
• Axis
– Check binocular vision
– Try maintaing the previous axis
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20. Presbyopia
• Plus Build-up
• Near range determination
– With J.C.C
– Push up method
– RAF ruler
• Near duochrome
• Dynamic near retinoscopy

21. • JCC is placed with its negative axis at 90
• Patient is shown Jacques blur point card
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22. • Hofstetters’ formulas
– Minimum expected
amplitude = 15 – 0.25
(age)
– Average expected
amplitude = 18.5 – 0.30
(age)
– Maximum expected
amplitude = 25 – 0.40
(age)
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23. Donder’s table for age-referenced
amplitude of accommodation
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24. • Minimum plus lens
giving maximum vision
for the required
working distance
Age Add
40 +1.00
45 +1.50
50 +2.00
55 +2.50
60 +3.00

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