The Ophthalmology Examinations Review - part 10 pot

304 The Ophthalmology Examinations Review Correct amblyopia Surgery Type of surgery Correct 10 overaction If ET is not corrected with spectacles Bilateral MR recession if deviation is greater for near Either bilateral MR recession or recess-resect if deviation is same for near and distance Recess-resect if amblyopia in one eye Other considerations Correct V or A pattern TOPIC 5 EXOTROPIA Whatare causes of exotroDias? “Exotropias are divergent misalignment of eyes.” “The most common cause is intermittent XT.” “Other causes include . . .” Causes of exotropias 1. Congenital Congenital XT Duane’s syndrome Type 2 Comitant XT 2. Acquired Intermittent XT Convergence insufficiency lncomitant XT 111 CN palsy Myasthenia gravis Thyroid eye disease IN0 Consecutive XT (after correction for ET) Sensory XT (disruption of BSV in children e.g. congenital cataract) Tell me about intermittent exotropias “Intermittent XT is a common divergent squint.” “It can be divided into 3 types based on severity of XT for near versus far.” “And into 3 phases ” intermittent XT 1. Classification Convergence insufficiency (worse for near, needs MR resection or recess-resect) Divergence excess (worse for distance, needs LR recession) Simulated excess (accommodative fusion controls deviation at near) True excess (diagnosed by adding “plus” 3D lens at near to control for accommodation) Basic (near and distance same, needs LR recession) 2. Phases 3. Clinical features Goes through 3 phases Phase 1 (intermittent XP at distance) Phase 2 (XT at distance, XP at near) Phase 3 (XT at distance and near) Age of onset 2 years Precipitated by illness, bright light, day-dreaming 385 386 The Ophthalmology Examinations Review Amblyopia not common Correct refractive errors (myopia) Correct amblyopia Orthoptic treatment Temporal retinal hemisuppression when eyes are deviated ARC and eccentric fixation may be present 4. Management Diplopia awareness Indications (4 classic indications) Fusional exercise (pencil pushups, base-out prism) Surgery Increase angle of XT Decreasing stereopsis Abnormal head posture Increase frequency of breakdown (i.e. progressing from Phase 1 to 2) TOPIC 6 VERTICAL SQUINTS AND OTHER MOTILITY SYNDROMES What are the types of vertical squints? Vertical squints 1. SO and 10 muscles SO palsy SO overaction 10 palsy 10 overaction 2. Multiple muscles Congenital fibrosis syndrome Double elevator palsy Dissociated vertical deviation (DVD) A and V patterns 3. Others (111 CN palsy, thyroid eye disease, blowout fracture) Tellme about inferior oblique overaction “10 overaction is a common vertical squint.” “50% of patients with essential or congenital ET have 10 overaction.” Inferior oblique overaction 1. Introduction Clinical scenarios With horizontal squints Primary (uncommon) Significance of 10 overaction Affects comesis Disruption of BSV Bilateral, but may be asymmetrical Paresis of one or both SO Contribute to large angle ET 2. Clinical features . 0 0 3. Surgery 0 V pattern - difference of > 15 prism D is considered significant Upshoot of eye in adduction Associated with SO underaction Grade +1 10 recession 8-10mm “How do you differentiate 10 overaction from DVD?” In 10 overaction Elevation of eye in adduction only (in DVD, in primary position and abduction as well) Hypotropia of fellow eye (in DVD, only hypertropia of affected eye) Base up prism over fellow eye will neutralize hypotropia (in DVD, only base down prism over affected eye will correct hypotropia) 387 388 The Ophthalmology Examinations Review Grade +2 10 myomectomy 10 myotomy at insertion Extirpation of 10 muscle Denervation Anteriorization of 10 tendon Grade+3 Grade+4 Marshall Park's point: 3mm lateral to lateral border of IR insertion + lmm behind Equivalent to 15mm of 10 recession Can correct for DVD as well HOW do you locate the 10 muscle durina surgery? Localization of 10 during surgery Isolate LR and IR Tubular/worm like structure 10 is a pink tendon within white Tenon's Pull 10 and feel tug at point of origin at orbital rim What are the advantaaes of a 10 mvomectomv ComDared to 10 recession? Myomectomy Recession Advantage Disadvantages Easy visualisation and technique Graded Skilled assistant not needed Reversible potentially Consistent result Anteriorization for DVD Lower risk of undercorrection Dilate pupils More difficult Not reversible Need skilled assistant Cannot be graded (all or none) Results less consistent No benefit for DVD What is the Duane's syndrome? "Duane's syndrome is an ocular motility disorder" "The main clinical feature is retraction of the globe on attempted adduction " "It can be classified into 3 types " Duane's syndrome 1. Classification Type 1 60% Limitation in abduction Can present as an ET 15% Limitation in adduction Can present as an XT 25% Type 2 Type 3 Systemic associations can Section 9: Squints and Pediatric Eye Diseases 389 Usually orthophoric limitation in both adduction and abduction 2. Clinical features Females more common Left eye in 60%, bilateral in 20% Retraction of globe on adduction (sine qua non) Co-contraction of MR and LR Associated with narrowing of palpebral fissure “What is the underlying pathogenesis?” Pontine dysgenesis with 111 CN innervating both MR and LR Ocular associations (8%) Ptosis Anisocoria Persistent hyaloid artery Myelinated nerve fibers Nystagmus Agenesis of genitourinary system Bone (vertebral column abnormalities) CNS (epilepsy) Upshoot or downshoot (lease phenomenon, do not mistake for 10 overaction!) 3. Ocular and systemic associations Epibulbar dermoids (associated Goldenhar syndrome) Systemic associations Deafness (sensory neural deafness is the most common association, 16% of all Duane’s) Dermatological (cafe au lait spot) Correct amblyopia Indications for surgery Wildervank’s syndrome (Duanes’s, deafness and Klippel-Fie1 anomaly of spine) 4. Management Abnormal head posture Unacceptable upshoot or downshoot Squint in primary position Liberal MR recession (may add LR recession) What is Brown’s syndrome? “Brown’s syndrome IS an ocular motility disorder.” “The main problem is pathology of the SO tendon.” “It can be either congenital or acquired ” I: Brown’s syndrome 1. Classification Congenital Bilateral in 10% Trauma Tenosynovitis (rheumatoid arthritis) Marfan’s syndrome Acromegaly Extraocular surgery (RD surgery) Pathology: short SO tendon, tight trochlea, nodule on SO tendon Acquired 2. Clinical features Classical triad of Normal elevation in abduction Defective elevation in adduction (most important) Less severe defective elevation in midline 390 The Ophthalmology Examinations Review Vertical gaze triad V pattern Hypotropia in primary position Positive forced duction test Downshoot in adduction No SO overaction (i.e. not 10 palsy!) Additional triad Widening of palpebral fissure on adduction 3. Management Correct amblyopia Spontaneous recovery common Indications for surgery Steroids (oral or injection into trochlear area) Abnormal head posture Diplopia in downgaze SO tenotomy or silicon expander Squint (hypotropia) in primary position Brown’s syndrome 10 palsy Deviation in primary position Slight Significant hypotropia Muscle sequalae Contraiateral SR overaction lpsilateral SO overaction A or V pattern *v *A Compensatory head posture Slight Marked chin elevation Forced duction test Positive Negative TOPIC 7 STRABISMUS SURGERY I MCQ: What are the indications of sauint suraeries? “In general, the indications of squint surgeries are ” Indications of squint surgeries 1. 2. Functional Anatomical (largely a “cosmetic” indication) Correct abnormal head posture Treat diplopia and confusion Correct misalignment (large angle, increase frequency of breakdown if intermittent) Restore BSV (if child is young enough) What are the principles of squint surgeries? “The principles of squint surgeries are .__” Principles of squint surgeries 1. 2. 3. Recess or resect? Recession is more forgiving MR or LR? If deviation at near > at distance, consider operation on MR. If distance > near, consider LR What are the indications of recess - resect operation on 1 eye? Amblyopia in 1 eye Constant squint in 1 eye Previous surgery in 1 eye Recess lmm = 2 prism D Vertical muscle surgery lmm = 3 prism D Resect lmm = 4 prism D Recession of MR more effective than LR 4. How much to correct? HO Wdo vou Derform a recession (resection) oeeration? “In a simple case of a XT with deviation worse at distance, I would perform a bilateral LR recession.” Recession operation 1. GA 2. U-shaped fornix-based conjunctival peritomy 3. Isolate LR Dissect Tenon’s on either side of LR muscle with Weskott scissors Isolate LR muscle with squint hook Clear off fascia1 sheath and ligaments with sponge Spread muscle using Stevens hook 391 392 The Ophthalmology Examinations Review 4. Stitch 2 ends of muscle with 610 vicryl 1 partial and 2 full thickness bites dividing muscle into 3 parts Clamp suture ends with bulldog For resection, measured distance to resect from insertion 5. 6. Measure distance of recession 7. Resuturing of LR Cut muscle just anterior to stitches (for resection, cut muscle at the desired site) Diathermise point of insertion to create ridge Stitch each end of the muscle to sclera OR stitch to insertion stump using a hangback technique For resection, stitch end to insertion stump 8. Close conjunctiva with 8/0 vicryl What are the indications for adjustable squint surgeries? "In general, it is indicated in adult squints when a precise outcome is needed " Adjustable squint surgeries 1. Indications Adult squints Best for rectus muscles Best with recession (principle: recess more than necessary and adjust postoperatively) Vertical squints Thyroid eye disease Blow out fractures VI CN palsy Reoperations 2. Contraindications Childhood squints Oblique dysfunctions and DVD Concomitant nystagmus Patient unwilling to cooperate after operation What are the complications of sauint suraeries? "The complications can be divided into intraoperative, early and late postoperative complications I' "The most dangerous intraoperative complications are scleral perforation and malignant hyperthermia." Complications of squint surgeries 1. lntraoperative ("M") Malignant hyperthermia (see below) Lost muscle MR most common muscle lost Muscle retracts into Tenon's capsule and usually ends up at the apex Slipped muscle Slip within muscle capsule Prevented by adequate suture Management similar to lost placement muscle NOES "How do you manage a lost muscle?" Stop operation (do not frantically dig around) Microscopic exploration (look for suture ends within Tenon's) Irrigate with saline and adrenaline (Tenon's usually appears more white) Watch for oculocardiac reflex when struc- tures are pulled If muscle cannot be found, abandon search Postoperatively, can try CT scan localization May consider reoperationlrnuscle transposi- tion surgery Section 9: Squints and Pediatric Eye Diseases 393 Scleral perforation Management Thinnest part of sclera (< 0.3mm just posterior to insertion) Potential sequalae: RD, endopthalmitis, vitreous hemorrhage Usually end up with chorioretinal scar Refer to retinal surgeon Stop operation and examine fundus Consider cryotherapy at site of scar 2. Early postoperative (“A) Alignment Most common complication Under- or over-correction Late misalignment caused by scarring, poor fusion, poor vision, altered accommodation Operate on 3 or more recti Tenon’s capsule is violated Anterior segment ischemia Adherance syndrome Allergic reaction Infection Mild conjunctivitis Preseptal cellulites/orbital cellulites Endophthalmitis (missed perforation) 3. Late postoperative (“D) Diplopia Scenarios Can be early or late Prisms Diplopia awareness Reoperation (adjustable surgery) In children, diplopia resolves because of new suppression scotoma or of fusion In adults, diplopia usually persists if squint is acquired after 10 years of age Management Droopy lids (ptosis) Dellen and conjunctival cysts HO Wdo YOU manaqe malignant hvperthermia? “Malignant hyperthermia is a medical emergency and requires immediate recognition and management.” Malignant hyperthermia 1. Mechanism of action Acute metabolic condition characterized by extreme heat production Inhalation anesthetics (e.g. halothane) and muscle relaxants (succinlycholine) trigger following chain of events Increase free intracellular calcium Excess calcium binding to skeletal muscles initiates and maintains contraction Muscle contraction leads to anerobic metabolism, metabolic acidosis, lactate accumulation, heat production and cell breakdown 2. Clinical features More common in children Early signs Isolated case or family history (AD inheritance) Tachycardia is earliest sign Unstable BP Tachypnea Cyanosis [...]... Geneticist Ocular prosthetist Medical social worker and RB support group Treatment methods Enucleation External beam radiotherapy Chemotherapy (eg chemoreduction, systemic chemotherapy, subconjunctival chemoreduction, intrathecal cytosine arabinoside) Focal therapy (eg laser, cryotherapy, radioactive plaque, thermotherapy) Orbital exenteration Trends In the past, enucleation was the standard treatment... (both sensitive and specific) Farnsworth - Munsell 100 hue test Based on matching hueskolor Consists of 84 colored discs Discs arranged in sequence (increasing levels of hue) Test is then scored Difference in hues between adjacent tablets is 1-4 nm Accurate in classifying color deficiency Very sensitive Time consuming and tiring The Ophthalmology Examinations Review 410 2 Nagel’s anomaloscope Based on matching... properties to emit photons Chamber Stores the active medium Mirrors at opposite ends to reflect energy back and forth (optical feedback) One of the mirror partially transmits the energy What are the lasers available in oehthalmoloav? “Lasers can be classified either by their clinical effects or by the active medium ” Laser classification 1 Clinical effects Photocoagulation (thermal effect) Temperature raised... worked or not worked?) If it does not work, then what? How long do you wait? If it works better than old therapy, how much is the effect? Statistics Sample size and power issues Randomization protocol Statistical significance Other issues Ethics 417 The Ophthalmology Examinations Review 418 What is primary prevention? Prevention strategies 1 2 3 Primary prevention - prevent disease, usually before occurrence... presence or absence of family history and whether tumor is unilateral or bilateral.” is a positive family history, the risk to the next child is 40%.” is no family history, but the tumor is bilateral, the risk to the next child is 6%.” is no family history and the tumor is unilateral, the risk to the next child is only 1%.” Genetic counselling Chance of following people to have a baby with RB: Parent Family... neovascularization Ciliary body involvment Failure of other treatment Tell m e about chemotherapy for retinoblastoma The indications for chemotherapy in RB are ” The current drugs under investigations include ” pic for R 3 y 1997; 104 Chemotherapy f o r RB 1 2 3 4 Indications Curative Chemoreduction for small and medium size tumors Vitreous/subretinal seeds (isolated local therapy is not good enough) Palliative... in retinoblastoma “Second cancers are leading causes of death in patients with the hereditary type of RB.” The incidence is The common tumors include , ,” ‘I The Ophthalmology Examinations Review 400 S e c o n d cancers in RB patients 1 2 Incidence Hereditary RB: 6% over lifetime Hereditary RB with external beam radiotherapy: incidence 1% per year in field of radiation (i.e 30% in 30 years, 50%... 2 5-3 0% of nonfamilial cases are still hereditary RB (The rate of new mutation is high) Therefore a negative family history does not rule out hereditary RB Hereditary (inherited RB gene) versus nonhereditary Hereditary (40%) Nonhereditary (60%) HO Wdo you counsel parents with a c h i l d w i t h RB? “Risk of “If there “If there “If there RB depends on presence or absence of family history and whether... tumors within the globe and external beam radiotherapy was the standard for large tumors extending out of globe Trend towards more conservative treatment for small to medium size tumors Increasing use of chemotherapy followed by focal therapy for small tumors and plaque radiotherapy for medium size tumors Factors to consider Tumor size and location Bilateral or unilateral disease Visual potential of... nonhereditarv tvDe of RB No risk of bilateral RB 395 The Ophthalmology Examinations Review 396 No risk of nonocular malignancies elsewhere Age of presentation: 2 years Distinguish between Bilateral versus unilateral Familial (positive family history) versus nonfamilial Bilateral (30%) Unilateral (70%) 1 0-1 5% of unilateral cases are still hereditary RB Therefore absence of bilateral RB does not rule out . neutralize hypotropia (in DVD, only base down prism over affected eye will correct hypotropia) 387 388 The Ophthalmology Examinations Review Grade +2 10 myomectomy 10 myotomy at. Stevens hook 391 392 The Ophthalmology Examinations Review 4. Stitch 2 ends of muscle with 610 vicryl 1 partial and 2 full thickness bites dividing muscle into 3 parts Clamp suture. and whether tumor is unilateral or bilateral.” “If there is a positive family history, the risk to the next child is 40%.” “If there is no family history, but the tumor is bilateral, the