REFRACTIVE SURGERY & STRABISMUS: PREDICTING & AVOIDING COMPLICATIONS Lionel Kowal, Ravindra Battu, Burton Kushner

Lionel Kowal ‘Straight [ening] guy for the queer eye’ Ocular motility clinic RVEEH Senior Clinical Fellow, U of Melbourne 1 st Vice President ISA Private Eye Clinic

Lionel Kowal $ interest

MODERN REFRACTIVE SURGERY > 12 yrs old n = millions Huge refereed literature Patient satisfaction & visual symptoms after LASIK Ophthalmology (2003) 110: % would recommend LASIK Halos 30% Glare 27% Starbursts 25% !!

GUIDELINES FOR REF SURGEON / STRABISMOLOGIST PROTECT PTS & REF SURGEONS FROM COMPLICATIONS THAT CAN BE ANTICIPATED NOT DENY PTS Q-O-L ENHANCING PROCEDURE

GUIDELINES FOR REF SURGEON / STRABISMOLOGIST 1.SCREENING TECHNIQUES – FOR ALL PTS See Kowal [2000] and Kowal & Kushner [2003] 2. THIS TALK: MODERATE / HIGH RISK GROUPS ONLY

REFRACTIVE SURGERY & STRABISMUS AT RISK GROUPS 1.HYPEROPIA 2.MONOVISION 3. ANISOMETROPIA 4. KNOWN / PAST STRAB.

IMPORTANT MESSAGE HYPEROPIA IS NOT THE MIRROR IMAGE OF MYOPIA

Population of hyperopes ≠ Population of myopes  mild amblyopia Predisposed to esodeviation Mild hyperopes: good UCV most of their lives

CONSIDER IN EVERY HYPEROPE Habitual hyperopic spectacle correction is being worn for good vision and possibly for control of esodeviation

PREDSIPOSITION TO STRAB IN HYPEROPES If recognised before RS: patient’s problem Not recognised before RS: your problem

Success of RS in myopia Primary factor : change in corneal curvature 2° factors : 2° aberrations, pupil, late ectasia

Factors for Success in hyperopia ALL 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, …

Treatment target in Myopia = Cyclo refraction Cyclo Ref should = Manifest Ref [within 0.5 DS] MR > CR : rule out underlying eXodeviation

Treatment target in hyperopia? No easy answer VISUAL PHYSIOLOGY LESSON #1 TYPES OF HYPEROPIA

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

TYPES OF HYPEROPIA DS Years TOTAL = Cyclo Ref PROBABLY STAYS STABLE FOREVER

TYPES OF HYPEROPIA DS Years TOTAL ACCOM AMP

TYPES OF HYPEROPIA DS Years TOTAL MANIFEST ABSOLUTE

TYPES OF HYPEROPIA DS Years TOTAL MANIFEST LATENT: ONLY REVEALED BY CYCLO

TYPES OF HYPEROPIA DSTOTAL M A FACULTATIVE Latent

FACULTATIVE HYPEROPIA Easily handled by patient’s normal accommodation ANY result in this range → good UCV If symmetric, good & comfortable UCV

HYPEROPIA DS TOTAL Manifest Absolute Facultative Latent Z Y X X : D age 20 : N 40 : N  Y : D 20 : N 40 : N

HYPEROPIA DS TOTAL Manifest Absolute Facultative Latent Z Y X Z : RISK OF VISUAL DISCOMFORT, I/MITT BLUR RE ≠ LE : RISK OF ABNORMAL BINOCULAR VISION. ACCOM SPASM  INCREASING ESODEVIATION.

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..

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

MEASURING FUSIONAL RESERVES

Medium term patient satisfaction Correction > Abs H is required : Manifest Hyperopia Max effect on D & N vision and E

REFRACTIVE SURGERY & STRABISMUS Assessing results : VISUAL PHYSIOLOGY LESSON #2

Assessing results Use 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

Psychophysically valid near tests * NVRI near [ETDRS]: 25cm : N 2.5 Can be 40 cm * Lea : 40 cm : 20/20 Can be 25 cm * M cards : American MA Evaluation of Impairment 5 th Edn T-hold : 0.3

NVRI NEAR TEST BAILEY LOVIE / ETDRS

LEA NEAR TEST

Case 1 : 32 yo WCF Wearing +4.75, + 5 DS OU no h/o strab Lasik → residual +2.25, +2 DS < 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

Case 2 : 24 yo WCF Wearing PALs to control near ET PALs NOT RECOGNISED ‘Successful’ RS: ET’ returns LESSON: the glasses! Mark Optical Centers Use automated vertometer that will automatically detect PALs and Δs

REFRACTIVE SURGERY AND STRABISMUS

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

The safe hyperope for RS With AH correction in place: phoria ≤ 5 ∆ BIFR > 5 ∆ LH ≤ 1 DS MANY [?most] low hyperopes

REFRACTIVE SURGERY & STRABISMUS AT RISK GROUPS 1.HYPEROPIA 2.MONOVISION 3. ANISOMETROPIA 4. KNOWN / PAST STRAB.

MONOVISION Fawcett n = : 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

HOW MUCH ANISOMETROPIA TO PRODUCE ABV ? 13 pts with ABV : 1.8 DS 105 pts with no ABV : 0.5 DS P < 0.001

MONOVISION Fawcett JAAPOS 2001: SURGICAL MV  UNCORRECTABLE DEFICIENCY OF HIGH QUALITY STEREO Also seen in k/conus

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

MONOVISION #2 52 yo PRE-REF SX R -4.00/-0.75x180 L-3.00/-1.5x160 6 Δ exophoria 60” stereo POST LASIK : blur, i/mitt diplopia R +0.25/-0.75x50; L -0.75/-0.25x130 [XT] D: 2 Δ, N: 10 Δ MV reduces motor fusion; phoria → tropia Lasik reversal of MV : now asymptomatic

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

UNPLANNED MONOVISION 50 PRK PTS [White; ESA,1997] 3 MO. DELAY B/W EYES 1/50: FUSIONAL CONV ↓ FROM 35 TO 5Δ 0/50 HAD SYMPTOMS TEMPORARY MV ≠ PERMANENT MV

MONOVISION:PROBLEMS ? 20+% LONG STANDING SURGICAL MV DEGRADES SENSORY / MOTOR FUSION MORE THAN CL MV AND TEMPORARY SURGICAL MV

REFRACTIVE SURGERY & STRABISMUS AT RISK GROUPS 1.HYPEROPIA 2.MONOVISION 3. ANISOMETROPIA 4. KNOWN / PAST STRAB.

Knapp’s Law Axial a’metropia not / less aniseikonogenic c.f. corneal a’metropia OTHER FACTORS: RETINAL STRETCHING SENSORY ADAPTATIONS

CORNEAL REFRACTIVE SURGERY CONVERTS AXIAL A’METROPIA SAFE ACCORDING TO KNAPP → CORNEAL A’METROPIA AT RISK ACCORDING TO KNAPP

EXAMPLE RE -2 Kav 44 LE -4.5 Kav 44.5 To end up with Plano OU, must produce corneal a’metropia

LENSECTOMY & ANISEIKONIA REFRACTIVE LENSECTOMY IN HIGH + MAY NOT BE ANISEIKONOGENIC EG: R +7 L DS/ -1.5 DC AFTER L LENSECTOMY Dissociated with 10 ∆ vertical ZERO subjective aniseikonia with gls! 1% with Awaya test nodal point ≠ cornea

REFRACTIVE SURGERY & STRABISMUS AT RISK GROUPS 1.HYPEROPIA 2.MONOVISION 3. ANISOMETROPIA 4. CURRENT / PAST STRAB.

4. KNOWN / PAST STRABISMUS 1. STRAIGHTENED STRAB 2. CURRENT STRAB 3. WEARING ∆ 4. ASTIGMATISM + STRAB

RS IN STRABISMIC MISALIGNED 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

RISK OF SPONTANEOUS DETERIORATION ‘SPONTANEOUS DETERIORATION’ WILL BE ATTRIBUTED BY PT TO RS  RISK IF: VERSION / DUCTION DEFICIT ALREADY PRESENT CVD / ALPHABET PATTERN

RISK OF SPONTANEOUS DIPLOPIA 2 SITUATIONS: STRAB ANGLE STAYS SAME : DEPTH OF SCOTOMA IMPORTANT STRAB ANGLE INCREASES / CHANGES: SIZE OF SCOTOMA IMPORTANT

RISK OF SPONTANEOUS DIPLOPIA DEPTH: BAGOLINI FILTER BAR - RETINAL RIVALRY [RR] HOW MUCH RR TO OVERCOME A SUPP SCOTOMA? ESP RELEVANT TO ACQ SUPPRESSION

BAGOLINI FILTER BAR aka SBISA BAR

RISK OF SPONTANEOUS DIPLOPIA SIZE : POLARIZED 4 DOT TEST [ARTHUR]

POLARISED 4 DOT TEST BRIAN ARTHUR

APPROXIMATE SCOTOMA SIZE TEST TO PATIENT SCOTOMA SIZE DISTANCE (feet) (degrees) ~~ ~ ~

SUPPRESSION SCOTOMA [SS] SS NOT ALWAYS ‘SAFE’ SMALL SHALLOW SS MORE AT RISK FOR DIPLOPIA THAN LARGE DEEP ONE BFB : > 5-6 SAFE 1-2 ? UNSAFE P4D : ?5  SAFE 0.5  ? UNSAFE

SUPPRESSION EG #1 I/MITT 15+Δ VERTICAL PHORIA NEVER HAD DIPLOPIA BFB #2 P4D SCOTOMA 1 DEG W4D: DIPLOPIA RR OVERCOMES SS → RISK OF SPONT DIPLOPIA

4. KNOWN / PAST STRABISMUS 1. STRAIGHTENED STRAB 2. CURRENT STRAB 3. WEARING ∆ 4. ASTIGMATISM + STRAB

WEARING PRISM ? INTENTIONAL ? MAINSTREAM ? QUIRKY ? INADVERTENT NEUTRALISE & THEN MEASURE FUSIONAL RESERVES

4. KNOWN / PAST STRABISMUS 1. STRAIGHTENED STRAB 2. CURRENT STRAB 3. WEARING ∆ 4. ASTIGMATISM + STRAB

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

OTHERS 1. GLASSES HAVE SUCCESSFULLY CAMOUFLAGED POS / NEG KAPPA NOW : PSEUDO STRAB WITHOUT GLS

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

OTHERS 2. VERTICALLY DECENTERED TREATMENT -23 DS LASIK ! ?POOR FIXATION ? VERTICAL KAPPA 14 Δ VERTICAL DIPLOPIA IMAGES SUPERIMPOSED BY Δ OR BY HCL

OTHERS 2.

OTHERS 3. CEREBRAL DIPLOPIA BILATERAL MONOCULAR DIPLOPIA NOT REFRACTIVE NOT FIXED / EXPLAINED BY HCL / TOPOGRAPHY / ABERROMETRY WELL … MAYBE …

REFERENCES KOWAL L Clin Exp Ophthal 2000: 28, New review submitted ? 2004/ 5 …………………………………………… KUSHNER B & KOWAL L Archives Ophthal March Patients …………………………………………… KOWAL L & BATTU R ‘Refractive Surgery and Diplopia’ in ‘STEP BY STEP LASIK SURGERY’ VAJPAYEE et al Chapter 13

REFRACTIVE SURGERY & STRABISMUS THANK YOU