REFRACTIVE SURGERY

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REFRACTIVE SURGERY STRABISMUS

• PREDICTING AVOIDING COMPLICATIONS
• Lionel Kowal, Ravindra Battu, Burton Kushner

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Lionel KowalStraight ening guy for the queer
eye

• Ocular motility clinic RVEEH
• Senior Clinical Fellow, U of Melbourne
• 1st Vice President ISA
• Private Eye Clinic

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Lionel Kowal interest

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MODERN REFRACTIVE SURGERY

• gt 12 yrs old n millions
• Huge refereed literature
• Patient satisfaction visual symptoms after
  LASIK Ophthalmology (2003) 110
  1371-1378
• 97 would recommend LASIK
• Halos 30 Glare 27 Starbursts 25 !!

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GUIDELINES FOR REF SURGEON / STRABISMOLOGIST

• PROTECT PTS REF SURGEONS FROM COMPLICATIONS
  THAT CAN BE ANTICIPATED
• NOT DENY PTS Q-O-L ENHANCING PROCEDURE

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GUIDELINES FOR REF SURGEON / STRABISMOLOGIST

• SCREENING TECHNIQUES FOR ALL PTS
• See Kowal 2000 and Kowal Kushner 2003
• 2. THIS TALK
• MODERATE / HIGH RISK GROUPS ONLY

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REFRACTIVE SURGERY STRABISMUS

• AT RISK GROUPS
• 1.HYPEROPIA
• 2.MONOVISION
• 3. ANISOMETROPIA
• 4. KNOWN / PAST STRAB.

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IMPORTANT MESSAGE

• HYPEROPIA IS NOT THE MIRROR IMAGE OF MYOPIA

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Population of hyperopes ? Population of myopes

• ? mild amblyopia
• Predisposed to esodeviation
• Mild hyperopes good UCV most of their lives

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CONSIDER IN EVERY HYPEROPE

• Habitual hyperopic spectacle correction is being
  worn for good vision
• and
• possibly for control of esodeviation

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PREDSIPOSITION TO STRAB IN HYPEROPES

• If recognised before RS
• patients problem
• Not recognised before RS
• your problem

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Success of RS in myopia

• Primary factor
• change in corneal curvature
• 2 factors
• 2 aberrations, pupil, late ectasia

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Factors for Success in hyperopiaALL OF

• Change in corneal curvature
• Amount symmetry of residual hyperopia
• Pre-existing predisposition to esodeviation
• Effect of RS on fusional reserve
• Decay of accom amp in future
• Amount of latent hyperopia
• 2 factors Acquired astigmatism, ? flap
  problems, 2 aberrations, loss of prismatic
  effects of spectacles,

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Treatment target in Myopia

• Cyclo refraction
• Cyclo Ref should Manifest Ref
• within 0.5 DS
• MR gt CR rule out underlying eXodeviation

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Treatment target in hyperopia? No easy answer

• VISUAL PHYSIOLOGY LESSON 1
• TYPES OF HYPEROPIA

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Treatment target in hyperopia? Need to know
ALL the H subtypes

• Absolute min for D T-hold
• Will allow good UCV
• Manifest max for D T-hold
• Max effect of H on D N vision and on alignment
• Total H Cyclo Ref
• Latent TOTAL MANIFEST will become manifest

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TYPES OF HYPEROPIA
TOTAL Cyclo Ref PROBABLY STAYS STABLE FOREVER
DS
Years
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TYPES OF HYPEROPIA
DS
TOTAL
ACCOM AMP
Years
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TYPES OF HYPEROPIA
DS
TOTAL
MANIFEST
ABSOLUTE
Years
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TYPES OF HYPEROPIA
DS
TOTAL
MANIFEST
LATENT ONLY REVEALED BY CYCLO
Years
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TYPES OF HYPEROPIA
DS
TOTAL
Latent
M
FACULTATIVE
A
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FACULTATIVE HYPEROPIA

• Easily handled by patients normal accommodation
• ANY result in this range ? good UCV
• If symmetric, good comfortable UCV

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HYPEROPIA
TOTAL
DS
Z
Latent
Manifest
Y
Facultative
X
Absolute
X D? age 20 N? 40 N?
Y D?
20 N? 40 N?
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HYPEROPIA
TOTAL
DS
Z
Latent
Manifest
Y
Facultative
X
Absolute
Z RISK OF VISUAL DISCOMFORT, I/MITT BLUR RE ?
LE RISK OF ABNORMAL BINOCULAR VISION. ACCOM
SPASM ? INCREASING ESODEVIATION.
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HYPEROPIA

• Any uncorrected H short of full manifest H ?
  accommodation ? accom conv ? eso tendency if
  motor fusion is inadequate
• With time, any Latent H ? Manifest Recurrent
  H ? accommodation ? accom conv ? eso tendency
  ..
• Asymmetric accommodation? accom spasm / varying
  accom convergence ? eso tendency ..

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Short term patient satisfaction after RS

• Abs H ? good UCV.
• Show that with this minimum vision - improving
  correction in place there is still adequate
  control of any latent E

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MEASURING FUSIONAL RESERVES
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Medium term patient satisfaction

• Correction gt Abs H is required Manifest
  Hyperopia
• Max effect on D N vision and E

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REFRACTIVE SURGERY STRABISMUS

• Assessing results
• VISUAL PHYSIOLOGY LESSON 2

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Assessing resultsUse GOOD vision charts

• Test monocularly for D to T-hold ETDRS / NVRI
  / Bailey Lovie
• Snellen not enough crowding 6/6 6/12
• Test monocularly for N to T-hold
• Rosenbaum J cards / usual cards ? N5
• OK to assess strength of near add
• NOT OK to test to T-hold

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Psychophysically valid near tests

• NVRI near ETDRS 25cm N 2.5
• Can be used _at_ 40 cm
• Lea 40 cm 20/20
• Can be used _at_ 25 cm
• M cards
• American MA Evaluation of Impairment 5th Edn
• T-hold 0.3

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NVRI NEAR TEST BAILEY LOVIE / ETDRS
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LEA NEAR TEST
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Case 1 32 yo WCF

• Wearing 4.75, 5 DS OU no h/o strab
• Lasik ? residual 2.25, 2 DS lt AH
• UCV 6/7.5 very happy
• BUT develops ET!
• No gls worn accom amp fine for 2 DS
• BUT accomm conv ? ET not happy

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Case 2 24 yo WCFWearing PALs to control near
ET

• PALs NOT RECOGNISED
• Successful RS ET returns
• LESSON look _at_ the glasses!
• Mark Optical Centers
• Use automated vertometer that will
  automatically detect PALs and ?s

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REFRACTIVE SURGERY AND STRABISMUS
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Case 50 yo WCF

• Wearing 5 DS OU CR 7 DS OU
• Uncorrected H 2DS
• Ref lensectomy / Array ? plano
• UCV 6/6 OU very happy
• 2 DS accomm ? accomm conv to control XT
• 20? XT very unhappy

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The safe hyperope for RS

• With AH correction in place
• phoria 5 ?
• BIFR gt 5 ?
• LH 1 DS
• MANY ?most low hyperopes

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REFRACTIVE SURGERY STRABISMUS

• AT RISK GROUPS
• 1.HYPEROPIA
• 2.MONOVISION
• 3. ANISOMETROPIA
• 4. KNOWN / PAST STRAB.

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MONOVISION

• Fawcett n 118 48
  PLANNED MV
• 11/48 ABNORMAL BINOCULAR VISION ABV
  ? 23
• intermittent or persistent diplopia
  visual confusion
• binocular blur requiring occlusion to focus
  comfortably
• NON - MV PTS 2/70 3 HAD ABV
• p significant
  ?13 pts with ABV

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HOW MUCH ANISOMETROPIA TO PRODUCE ABV ?

• 13 pts with ABV 1.8 DS
• 105 pts with no ABV 0.5 DS
• P lt 0.001

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MONOVISION

• Fawcett JAAPOS 2001
• SURGICAL MV ? UNCORRECTABLE DEFICIENCY OF HIGH
  QUALITY STEREO
• Also seen in k/conus

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MONOVISION 1

• 55 yo PRE - REF SX
• R -2.75/-1x85 6/9 L -2.25/-0.25x180 6/9
• D Ortho. N 8 ? Esophoria. 60
  stereo
• POST LASIK diplopia / visual confusion
• R P 6/6 L sc 6/15 Rx -1.75 DS
• intermittent near ET 6 ?
• MV ? motor fusion phoria ? tropia
• Glasses to correct MV symptoms fixed

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MONOVISION 2

• 52 yo PRE-REF SX
• R -4.00/-0.75x180 L-3.00/-1.5x160
• 6 ? exophoria 60 stereo
• POST LASIK blur, i/mitt diplopia
• R 0.25/-0.75x50 L -0.75/-0.25x130
• XT D 2 ?, N 10 ?
• MV reduces motor fusion phoria ? tropia
• Lasik reversal of MV now asymptomatic

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MONOVISION? FIXATION SWITCH DIPLOPIA

• Amblyopic eye with scotoma becomes fixing eye
  in some situations.
• Habitually fixing eye is now the deviating eye in
  those situations no scotoma ? diplopia
• no definite cases in this series

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UNPLANNED MONOVISION

• 50 PRK PTS White ESA,1997
• 3 MO. DELAY B/W EYES
• 1/50 FUSIONAL CONV ? FROM 35 TO 5?
• 0/50 HAD SYMPTOMS
• TEMPORARY MV ? PERMANENT MV

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MONOVISIONPROBLEMS

• ? 20
• LONG STANDING SURGICAL MV
• DEGRADES SENSORY / MOTOR FUSION MORE THAN CL MV
  AND TEMPORARY SURGICAL MV

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REFRACTIVE SURGERY STRABISMUS

• AT RISK GROUPS
• 1.HYPEROPIA
• 2.MONOVISION
• 3. ANISOMETROPIA
• 4. KNOWN / PAST STRAB.

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Knapps Law

• Axial ametropia not / less aniseikonogenic
• c.f.
• corneal ametropia
• OTHER FACTORS RETINAL STRETCHING
• SENSORY ADAPTATIONS

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CORNEAL REFRACTIVE SURGERY

• CONVERTS AXIAL AMETROPIA
• SAFE ACCORDING TO KNAPP
• ?
• CORNEAL AMETROPIA
• AT RISK ACCORDING TO KNAPP

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EXAMPLE

• RE -2 Kav 44
• LE -4.5 Kav 44.5
• To end up with Plano OU, must produce corneal
  ametropia

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LENSECTOMY ANISEIKONIA

• REFRACTIVE LENSECTOMY IN HIGH MAY NOT BE
  ANISEIKONOGENIC
• EG R 7 L 0.25 DS/ -1.5 DC
• AFTER L LENSECTOMY Dissociated with 10 ?
  vertical
• ZERO subjective aniseikonia with gls!
• 1 with Awaya test
• Ametropia _at_ nodal point ? cornea

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REFRACTIVE SURGERY STRABISMUS

• AT RISK GROUPS
• 1.HYPEROPIA
• 2.MONOVISION
• 3. ANISOMETROPIA
• 4. CURRENT / PAST STRAB.

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4. KNOWN / PAST STRABISMUS

• 1. STRAIGHTENED STRAB
• 2. CURRENT STRAB
• 3. WEARING ?
• 4. ASTIGMATISM STRAB

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RS IN STRABISMICMISALIGNED OR STRAIGHTENED

• NEED TO ANSWER
• Q1. RISK OF DETERIORATION OF ALIGNMENT
• Q2. RISK OF DIPLOPIA
• - SPONTANEOUSLY NO REF SX
• - SUCCESSFUL REF SX
• - IMPERFECT REF SX

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RISK OF SPONTANEOUS DETERIORATION

• SPONTANEOUS DETERIORATION WILL BE ATTRIBUTED BY
  PT TO RS
• ? RISK IF
• VERSION / DUCTION DEFICIT ALREADY PRESENT
• CVD / ALPHABET PATTERN

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RISK OF SPONTANEOUS DIPLOPIA

• 2 SITUATIONS
• STRAB ANGLE STAYS SAME
• DEPTH OF SCOTOMA IMPORTANT
• STRAB ANGLE INCREASES / CHANGES
• SIZE OF SCOTOMA IMPORTANT

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RISK OF SPONTANEOUS DIPLOPIA

• DEPTH
• BAGOLINI FILTER BAR - RETINAL RIVALRY RR
• HOW MUCH RR TO OVERCOME A SUPP SCOTOMA?
• ESP RELEVANT TO ACQ SUPPRESSION

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BAGOLINI FILTER BAR aka SBISA BAR

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RISK OF SPONTANEOUS DIPLOPIA

• SIZE
• POLARIZED 4 DOT TEST ARTHUR

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POLARISED 4 DOT TEST BRIAN ARTHUR
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• APPROXIMATE SCOTOMA SIZE
• TEST TO PATIENT
  SCOTOMA SIZE
• DISTANCE (feet)
  (degrees)
• 1 5.25
• 2 2.63
• 3 1.75 4 1.32
  5 1.05 6 0.88
• 10 0.53 15 0.3
  5 20 0.26

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SUPPRESSION SCOTOMA SS

• SS NOT ALWAYS SAFE
• SMALL SHALLOW SS MORE AT RISK FOR DIPLOPIA THAN
  LARGE DEEP ONE
• BFB gt 5-6 SAFE 1-2 ? UNSAFE
• P4D ?5? SAFE 0.5? ? UNSAFE

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SUPPRESSION EG 1

• I/MITT 15? VERTICAL PHORIA
• NEVER HAD DIPLOPIA
• BFB 2
• P4D SCOTOMA 1 DEG W4D DIPLOPIA
• RR OVERCOMES SS ? RISK OF SPONT DIPLOPIA

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4. KNOWN / PAST STRABISMUS

• 1. STRAIGHTENED STRAB
• 2. CURRENT STRAB
• 3. WEARING ?
• 4. ASTIGMATISM STRAB

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WEARING PRISM

• ? INTENTIONAL
• ? MAINSTREAM ? QUIRKY
• ? INADVERTENT
• NEUTRALISE THEN MEASURE FUSIONAL RESERVES

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4. KNOWN / PAST STRABISMUS

• 1. STRAIGHTENED STRAB
• 2. CURRENT STRAB
• 3. WEARING ?
• 4. ASTIGMATISM STRAB

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ASTIGMATISM WITH STRAB
BEWARE OF CHANGE IN CYL AXIS WHEN PT CHANGES
FROM BINOCULAR TO MONOCULAR FIXATION 1/6
CHANGES BY 18 DEG SITTING TO SUPINE De Faber
1/4 CHANGES BY 13 DEG Becker No
change EXPECT GREATER CHANGES IN AXIS IF ANY
CYCLOVERTICAL STRAB
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OTHERS 1.

• GLASSES HAVE SUCCESSFULLY CAMOUFLAGED POS / NEG
  KAPPA
• NOW PSEUDO STRAB WITHOUT GLS

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OTHERS 2.

• VERTICALLY DECENTERED TREATMENTS
• HORIZONTAL KAPPA COMMON
• VERTICAL KAPPA 1/5000 IN A STRAB PRACTICE
• HORIZONTAL DECENTRATION
• ? INDUCED H ? ABSORBED BY MOTOR FUSION ?
  LITTLE / NO RISK OF DIPLOPIA
• VERTICAL DECENTRATION
• DIPLOPIA MORE LIKELY

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OTHERS 2.

• VERTICALLY DECENTERED TREATMENT
• -23 DS LASIK !
• ?POOR FIXATION
• ? VERTICAL KAPPA
• 14? VERTICAL DIPLOPIA
• IMAGES SUPERIMPOSED BY ? OR BY HCL

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OTHERS 2.

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OTHERS 3.CEREBRAL DIPLOPIA

• BILATERAL MONOCULAR DIPLOPIA
• NOT REFRACTIVE
• NOT FIXED / EXPLAINED BY HCL / TOPOGRAPHY /
  ABERROMETRY
• WELL MAYBE

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REFERENCES

• KOWAL L
• Clin Exp Ophthal 2000 28, 344-346
• New review submitted ? 2004/ 5
• KUSHNER B KOWAL L
• Archives Ophthal March 2003 28 Patients
• KOWAL L BATTU R
• Refractive Surgery and Diplopia in
• STEP BY STEP LASIK SURGERY
• VAJPAYEE et al 2003. Chapter 13

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REFRACTIVE SURGERY STRABISMUS

• THANK YOU