Squint Club 2006Squint Club 2006

ACTIVE TREATMENT OFCONGENITAL NYSTAGMUS:RATIONALE & RESULTS

ACTIVE TREATMENT OFCONGENITAL NYSTAGMUS:RATIONALE & RESULTS

LIONEL KOWALLOTS of assistance from Drs Elaine Wong, Steven Bush, Joanne Dondey & Larry Abel

SQUINT CLUB 2006

LIONEL KOWALLOTS of assistance from Drs Elaine Wong, Steven Bush, Joanne Dondey & Larry Abel

SQUINT CLUB 2006

Squint Club 2006Squint Club 2006

OVERVIEW OF THIS TALKOVERVIEW OF THIS TALK

1. Overview of cong N2. Treatments3. Audit of recordings4. Audit of surgeries

1. Overview of cong N2. Treatments3. Audit of recordings4. Audit of surgeries

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APOGOLIES FOR DIFFICLUT TERNIMOLOGY

Congenital Aperiodic Periodic Alternating Nystagmus PAN

Latent Manifest Latent Nystagmus LMLN, aka Fusion Maldevelopment Syndrome or FMS

Dual Jerk nystagmus : Not a personal insult - combination pendular plus jerk nystagmus

Nystagmus usu referred to as N

IN OFFICE ASSESSMENT OF CONGENITAL

NYSTAGMUS

IN OFFICE ASSESSMENT OF CONGENITAL

NYSTAGMUS

Types of congenital nystagmus - how to differentiate them in

the office

Types of congenital nystagmus - how to differentiate them in

the office

2 Main types of congenital N:

Lower case ‘cN’ = congenital N = any sort of very early onset N

1.Congenital N

Upper case ‘CN’ - a specific type of cN

Synonyms: Congenital Motor N

Idiopathic Infantile NIIN

2 Main types of congenital N:

2. LMLNLatent Manifest Latent N

Synonyms: Manifest Latent N

Fusion Maldevelopment N FMNS

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Congenital N

Result of abnormal bilateral symmetric acuity development @ a CRITICAL PERIOD in very early visual devpt.

Hence frequent association with : OCA [foveal ± disc dys- / hypo-plasia], high refractive errors, bilateral optic n hypoplasia, PVL, bilateral cong cataracts, …..

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LMLN

Result of Asymmetric acuity development and/or abnormal development of binocularity @ a CRITICAL PERIOD in very early visual devpt hence associated with CET, early monocular visual loss, PVL, …

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CN

Involuntary, bilateral, conjugate [RE = LE] oscillation beginning ≤ 6 mo

Usually horizontal ± torsional Decreased at certain angle[s] =

null zone NZ Blocked with convergence [also NZ]

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CN

Commonly gaze evoked:– R beating in R gaze

actually to R of NZ– L beating in L gaze

actually to L of NZ

Usual CN waveform [decreasing velocity slow phase] is UNIQUE

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Acuity in CN : FOVEATION

When eye changes direction, speed of oscillation slows down in order to reverse direction = foveation period

[velocity < 5 º/sec; flat part of the EMR]

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Acuity in CN : FOVEATION

BCVA depends on:1. Duration of foveation period2. Persistence and effect of

factors that initiated the CN [foveal hypoplasia, optic n hypoplasia, high cyls, …]

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CN: 2 NZs LITTLE / NO N

ECCENTRIC NZ : drives AHP Usu stable / ‘hard wired’ but can vary time / age Can be turn, tip, tilt [T3] or combo. Same with either eye fixing

CONVERGENCE NZ near acuity better than distance medial recti ‘brake’ the CN

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CN Natural history: 3 phases over the first 12mo

Phase I : first 2-3 mo of life– Purposeless eye mvmts - as if blind – No jerk N– large amp, low frequency ‘triangular’ – No voluntary horizontal pursuit / saccades

–Normal vertical OKN, pursuit and saccades - excludes apparent blindness & avoids MRI

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Natural history : Phase II pendular

Age 6-12 moSymmetrical, low-amplitude, pendular N

May remain phase II without proceeding to phase III

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Natural history: Phase III adult waveform

– Age 12+ mo–‘Adult’ jerk waveform –development of eccentric null

zone with AHP–± compensatory head nodding

– Phases are per Reinecke– Hertle does not show same evolution – Difference: ?sampling ?selection bias

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CN variant : P A N

Relatively common VERY under diagnosed

Melbourne: ?30% of albinos

FAT SCAN IMPORTANT - are there ANY photos that shows a face turn the other way?

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CN variant : P A N

Oscillates between 2 NZs approx 90° apart

O/wise identical to CN NZ changes : cycle of 1 to 10 minAcquired PAN : cycle usu 2 min

Usu Aperiodic e.g. 8 min to L & 1 min to R

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Latent Manifest Latent Nystagmus LMLN

Main EMR feature: Decreasing velocity slow

phase [not unique - also gaze paretic N]

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Latent Manifest Latent NLMLN

Main clinical feature:

Fast phase to fixing eye - UNIQUE

LMLN : is a conjugate bilateral monocularly ‘driven’ N - waveform depends on which eye is fixing, and whether that eye is in the AD- or AB- ducted position

Slit lamp: T component common

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LMLN can resemble CN

Null in adduction for each eye [less N, vision better] - can look like CN conv null

Nystagmus on lateral gaze: LE in LG: BE have N L RE in RG: BE have N R SUPERFICIALLY SIMILAR TO GAZE EVOKED N OF CN

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LMLN Face turn to fixing eye

2 NZs improve VA:H & Thence 2 types of AHP

NZs in LMLN are monocular NZ for blocking the H component of

LMLN: fixation in adduction Medial rectus acts as a ‘brake’

– Face turn to fixing eye - can superficially resemble PAN

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LMLN Head tilt to fixing eye

NZ for blocking T component of LMLN : in intorsion

sup oblique acts as a ‘brake’Head tilt to fixing eyeSame mechanism causes DVD of other eye

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CN / PAN & LMLN

RECAP ….

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Congenital N

Result of abnormal bilateral symmetric acuity development

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WHY LMLN?

Result of Asymmetric acuity development &/or abnormal development of binocularity

BOTH LMLN & CN seen together in very early onset Cong ET

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Both CN & LMLN may have:

N greater in lateral gazeLatent componentN worse with monocular cf binocular fixationdifferent mechanisms in CN / LMLN

Strabismus CN: some. LN: nearly all

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Both CN/PAN & LMLN may have:

Conv nulldifferent mechanisms

Alternating face turnsdifferent mechanisms

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CN vs. LMLNIN OFFICE GUIDELINES

T: prob LMLNOCA : bilateral VA CNN fixing eye: LMLN

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CN vs. LMLNIN OFFICE GUIDELINES 2

Pref for fixation in ABduction : CN

Smooth pursuit asymmetry: LMLN

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P A N

Prolonged in- office exam - check AHP while talking to parents for PAN [show age appropriate DVD]

FAT scan to determine consistency

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SLIT LAMP EXAM

Look for TIDs of iris with decentred beam in a darkened room

Makes OCA likely

Hermansky Pudlak looks just like OCA : ask re: any possible bleeding diathesis

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SLIT LAMP EXAM

The ‘Designs for Vision’ examination paddle with reduced Snellen chart is a good way to – determine conv null– any T component [usu LMLN]– fast phase to fixing eye– Smooth pursuit asymmetry [usu

accompanies LMLN]

When to record and why record eye movements for

nystagmus diagnosis?

When to record and why record eye movements for

nystagmus diagnosis?

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Does everyone with wiggly eyes need to be recorded?

Usually - not if you’re absolutely certain about the diagnosis and have all the information you need for management

EMR is to cN today what ECG was to arrhythmia 50 y ago - would you dream of managing an arrhythmia without ECG?

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What if you’re not sure?

CN waveforms are unique - can confirm diagnosis

Can save patient expensive imaging studies (esp. small children)

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What if you’re not sure?

What distinctions can you make?–Acquired vs. cong types N–CN vs. cong PAN–CN vs. LMLN–N vs. saccadic oscillations

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CN waveforms

Pathognomonic for CN

Approx 15 waveforms described ‘Jerk’ or ‘pendular’ on basis of slow

componentJerk waveforms may appear pendular clinically

Analysis of waveform may prognostic information about potential VA

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Latent nystagmus

EMR often required to determine whether LN is due to CN or LMLN

“The eye is quicker than the eye”

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Assessing effects of treating CN

CN’s variability makes clinical assessment of change difficult

Recording can objectively document– Changes in foveation

Can facilitate better VA– Shift in null position

Will reduce or eliminate AHP– Broadening of null

having best possible vision over a wider range of gaze angles improves patients’ functional field of vision

…all best demonstrated with EMR

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Summary

EMR can provide clinicians with two major forms of assistance:

1) establishing / confirming a diagnosis when the clinical presentation is atypical or ambiguous

2) Document outcome of treatment

Modern Treatment

Options In congenital

Nystagmus

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Treatment goals in CN 1Directly Improve VA Treat refractive error Treat amblyopia

Stabilize/ reduce intensity N (increase “foveation”) to improve VA

Prisms CLs Surgery

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Treatment goals in CN 2Normalize head posture Prisms Surgery

Broaden NZ to expand effective visual field

Prisms CLs Surgery

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Medical treatments

Drugs - barely explored

New epilepsy

drugs Lyrica,

Memantine,

Neurontin

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Prisms - for convergence null

– Induce fusional convergence – 7 ∆ base out prisms with -1 DS OU to

compensate for convergence induced accommodation [CA/C ratio]

– Can be used long term – Useful preop test for

suitability for artificial divergence surgery

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Contact lenses

VA ≥ optical effect alone – CL sometimes expands NZ & improves

foveation time

– ? Stimulates conjunctival proprioceptors

Dell’Osso 1988. Contact lenses and congenital nystagmus. Clin. Vision. Sci. 3:229-232

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Surgical treatments

#1: ARTIFICIAL DIVERGENCE #2: KESTENBAUM / ANDERSON

#3: HERTLE TENOTOMY#3A: 4 MUSCLE RECESSION

#4: LMLN SURGERY

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#1: ARTIFICIAL DIVERGENCE SURGERY

Cuppers,1970’s. Popularised by Spielman 1990’s. >100 cases to AAPOS 10y ago

If there is a conv null for distance with ∆, BMR creates an exophoria that ‘drives’ a conv null

INDICATIONS–CN / PAN–Convergence null for distance–Some sensory and motor fusion or

BMR constant XT

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ARTIFICIAL DIVERGENCE SURGERY

COMPLICATIONS AND EXPECTATIONS

– 10% consec XT– Improved VA & field– Decreased AHP & nystagmus

BEST OPERATION FOR NYSTAGMUS

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#2: HORIZONTAL NULL POSITION SURGERY

KESTENBAUM / ANDERSON50y history!Rc/Rs OU for face turn13mm OU for 15º - 25º face turnAnderson* : only the Rc component

1. INDICATIONSCN with consistent Eccentric NZR/O APANINADEQUATE CONVERGENCE DAMPING >12 mo old (Child is walking)

* Hugh Taylor’s grandfather

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COMPLICATIONS AND EXPECTATIONS OF KESTENBAUM / ANDERSON SURGERY

Improves AHP Improves VA in many Expands NZ & effective field of vision Small Under- > Over- Corrections frequent Consecutive Strabismus infrequent but difficult Limitation of Gaze - pseudo Gaze Palsy - may

never fully recover

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Non- specific +ve effect of CN surgery

K’baum operation usu:– Expanded null zone * – Improved acuity **IRRESPECTIVE of whether the K’Baum achieved the desired goal

*Dell'Osso,L,Flynn, J.T.: Congenital Nystagmus

Surgery: A Quantitative Evaluation of the Effects.Arch. Ophthalmol.97:462-469, 1979

** John Norton Taylor, RVEEH in Aust NZ J Ophthal, and many others

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Intriguing Question

Does K’baum surgery have a non-specific +ve effect that we can exploit ?

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HERTLE RESEARCH

1. In beagles with cong SSN tenotomy & resuture improves the features of the EMR that correlate with improved VA

2. Proprioceptors in ‘Enthesis’ [where tendon inserts into sclera] are abnormal in human CN pts [?cause ?effect]

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Lakota Copper

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#3: HERTLE TENOTOMY OPERATION

If K’baum and artificial divergence surgery not appropriate “Tenotomy & resuture back to insertion” improves foveation on EMR in nearly all CN pts and improves VA in about 50%

Hertle RW. Horizontal Rectus Tenotomy in Patients with

Congenital Nystagmus. Ophthalmology. 2003;110:2097-2105

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#3: TENOTOMY ONLY INDICATIONS

CN No alternative surgery appropriate No Convergence or Eccentric Null ≥12 mo old ≤10% of CN Patients appropriate

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#3A: Large Rc all horizontal recti

Bietti / Bagolini 50y history Recess all muscles +++ : to suppress the

CN improve vision, cosmesis, face turns

Largely abandoned in Europe - resurrected in USA / Mexico in 80’s

Reinecke improves VA only in PAN

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4. Surgery for LMLN

ReineckeCorrrect ET or XT perfectly

and convert LMLN to LNImproved face turns Improved VA

Audit of EMR:How EMR can help

diagnosis and treatment of patients

with nystagmus

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Audit methods

Files of 79 LK private patients with presumed cN reviewed

55 patients had EMR Recordings and clinical diagnosis

were compared

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The population studied

59%20%

6%

15%

CN LMLN CN and LMLN Other (including APAN)

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EMR versus clinical assessment

n=55

40%

18%

9%

33%

EMR confirms clinical diagnosis Indeterminate clinical assessment, EMR diagnosisEMR shows clinical diagnosis incorrectEMR indeterminate

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EMR diagnosis, Indeterminate clinical diagnosis – 33%

PG, 18 presented requesting treatment of N.

Vision was R 6/24 L6/30, bin 6/10.

ET, Direction of fast phase unclear, convergence null

Oscillopsia Uncertain office diagnosis EMR : CN

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Office diagnosis incorrect -16%

CS, age 5, presents with a L FT and tilt. Had undergone surgery previous year for XT.

R6/18 L 6/15. Fast beat in direction of fixation, no

convergence null, no eccentric null. Office diagnosis LMLN EMR demonstrates CN

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EMR indeterminate – 11%

4 patients with APAN, all correctly diagnosed as having a CN waveform. Unable to demonstrate EMR features of APAN

1 patient with very asymmetric pendular nystagmus – CN confidently excluded but no definite diagnosis made

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Limitations of EMR

Not readily available Equipment limitations limit

assessment of vertical nystagmus and positions of extreme gaze

Cooperation of patients - v. difficult under 12 mo, difficult under 2y

Melbourne: LUCKY to have Larry Abel

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Limitations of EMR

THANK YOU LARRY!

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Accuracy of clinical signs

Clinical signs evaluated:– Direction of N ? in direction of gaze or ?

to fixing eye– Convergence null– Eccentric null

Final diagnosis after serial clinical assessment, FAT, EMR, and clinical conferences

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Accuracy of clinical signs

0102030405060708090

100

1. Conv. Null inCN

2. Jerk to gazedir.

1. & 2. combinedEcc. Null in CN Jerk to fixn

Sensitivity Specificity

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Conclusions 1

3 tests with >95% specificity– Eccentric null in CN– Conv. null and jerk to gaze direction in

CN– Jerk to fixing eye in LMLNDiagnosis made with these signs is

likely tobe accurate

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Conclusions 2

Although a good “stand alone” test, jerk to fixing eye will still miss ~25% of LMLN

Convergence null and jerk to gaze direction will miss most CN

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Conclusions 3

EMR valuable in evaluation of cN, and will become more important if / as surgery becomes more popular

Serial clinical assessment helpful esp. F.A.T in APAN – EMR may miss this diagnosis

Be aware of limitations of office exam

SURGERY IN CONGENITAL

NYSTAGMUS

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AUDIT OF LK SURGERIES seen during 2003-5

n=20 16 : EMR confirmation 10 ‘pure’ CN 3 PAN 5 LMLN [EMR 4] 2 CN + LMLN [EMR 1]

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KESTENBAUM n=6

2 with ≥ 1 line improvement – #1: 6/12 OU to 6/6, 6/9– #2: 6/18 OU to 6/12 OU

5/6: AHP fixed 3/6 need 2nd surgery:

1. AHP over corrected2. Consec XT3. Pre-existing strab not fixed

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Strabismus + Hertle n=6

5 for ET & 1 for XT + Hertle on other horizontal recti

1/6 improved VA– From 6/15 OU to 6/9 OU

1/6 VA worse– From 6/30, 6/60 to 6/45, HMComorbidities: midline brain anomalies

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Strabismus + Hertle n=6

1/6: fixation switch : problems1/6 PAN. E + conv null for D

confirmed with ∆ glasses. Sx: NO effect on FT. 2nd surgery to augment BMR - some improvement

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Artificial divergence + Hertle n=2

#1: PAN with alternating FT– Corrected

#2: PAN and albinism– VA 6/36 OU to 6/22 OU– Consec XT* : 2nd op to advance one MR– Alt FTs much improved

* +ve Kappa of OCA makes this look worse

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Large 4 muscle Rc n=1

PAN with no face turns - null zone in primary position– Surgery

MRRc 9 OU, LRRc 10 OU

– VA improved6/30 to 6/19 OU

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Surgery for LMLN n=2

#1: 35∆ XT with oscillopsia– MRsOU previous LR Rc OU

– No oscillopsia VA: from R6/22, L6/25, BE 6/9 to R6/12,

L 6/9, BE 6/9

#2: 45 ∆ ET– BMMRc– Residual 35 ∆ ET– No VA improvement

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Summary : Effect on VA

– 5/20 improved VA ≥ 1 line2/5: .. to 6/12 2/5: 2 line improvement 6/30 to 6/196/12 to 6/6

– 1/20 : VA worse no explanation

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Summary : Effect on AHP

Any sensible surgery usu effective for AHP in CN and PAN

9/12 : improved AHP

5 require 2nd op3 were for residual / induced

strabismus2 required 2nd op to improve residual

AHP

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Summary Effect on oscillopsia

Excellent2/2 with resolution of symptoms

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Becoming an expert

Read the following authors:1. Hertle2. Reinecke 3. Spielman4. Abadi

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A LOT OF WORK!!FOR LITTLE BENEFIT?

Ask the patients! When a snail gets a ride on the back

of a tortoise, the observer isn’t impressed. The snail thinks it’s fantastic!*

* Tychsen

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LAST SLIDE!!

THANK YOU FOR YOUR TIME AND PERSEVERANCE

FOR MORE EFFECTIVE CONFERENCE LECTURESFrom New Scientist, 26 January 2006, page 17

Stuart Brody [Paisley, UK] compared effects of different sexual activities on BP when a person is later stressed. 24 F & 22 M kept diaries of when they had penile-vaginal intercourse (PVI) & non- coital sex. They then underwent a stress test involving public speaking and mental arithmetic out loud.

The PVI group were least stressed; their BP normalised faster than the non-coital group. Abstainers had the highest BP response to stress.

The effects are not attributable to short-term relief from orgasm, but endure for at least a week. Release of oxytocin might account for the effect.