OSCE-1 CASES for the Exam

1- Unilateral facial cutaneous angioma, hemiplegia, and glaucoma

A 1-year-old boy has a unilateral facial cutaneous angioma, hemiplegia, and glaucoma. What is the most likely diagnosis?
nevus of Ota

tuberous sclerosis

neurofibromatosis

Sturge-Weber syndrome 

Discussion:

Glaucoma is associated with several of the conditions that comprise the phakomatoses. The phakomatoses are a group of disorders characterized by inheritability with variable penetrance and the formation of hamartias and hamartomas in multiple organs including the eye.

In tuberous sclerosis, common manifestations include adenoma sebaceum, shagreen patch, “ash leaf” spot on the skin, epilepsy, and mental deficiency due to intracranial calcified hamartomas. Ocular features include peripapillary astrocytic hamartomas and sebaceous adenomas of the eyelid. Glaucoma very rarely occurs and typically arises secondary to retinal complications such as vitreous hemorrhage or retinal detachment.

Neurofibromatosis is an autosomal dominant neurocutaneous disorder characterized by abnormal proliferations of peripheral nerve elements. Typical clinical features include neurofibromas, cafe-au-lait spots, intracranial calcifications, and central nervous system tumors. Ocular findings include plexiform neuromas of the eyelids, optic nerve glioma, and retinal hamartomas. Glaucoma is an occasional problem in neurofibromatosis.

Individuals with oculodermal melanocytosis (nevus of Ota) typically show unilateral deep dermal pigmentation involving the first and second division of the trigeminal nerve. Usually, the ipsilateral eye shows hyperpigmentation of the sclera, conjunctiva, iris, or fundus. Unilateral glaucoma in the involved eye is common and can be either open-angle or acute angle-closure glaucoma.

The cutaneous angioma of Sturge-Weber (encephalotrigeminal angiomatosis) syndrome also occurs unilaterally along the first and second divisions of the trigeminal nerve. However, in contrast to the hyperpigmentation of the nevus of Ota, the cutaneous angioma consists of loosely arranged, dilated capillaries in the dermis and subcutaneous tissue and typically appears burgundy colored (port-wine stain). The meningeal hemangioma usually occurs on the same side as the facial angioma and frequently causes mental deficiency and seizures, which can lead to hemiparesis, hemiplegia, and homonymous hemianopsia. Common ocular findings include diffuse choroidal hemangioma and glaucoma, both congenital and adult-onset. The etiology of the glaucoma is not well understood, but might be due to a combination of developmental angle anomalies and elevated episcleral venous pressure.

2- Pediatrician treating 10-year-old girl for conjunctivitis

A pediatrician has been treating a previously healthy 10-year-old girl for conjunctivitis with sulfacetamide drops for 2 weeks, but the redness has worsened and is now associated with photophobia. Most of the redness is localized in the perilimbal area, there are small keratic precipitates, the anterior chamber has 2+ cell with 1+ flare, the pupil shows 3 clock hours of posterior synechiae, best-corrected VA is 20/50, and the review of systems is negative. What is the best initial treatment?
rheumatologic consultation to begin cytotoxic immunosuppressive agents

topical prednisolone 1% every 2 hours and homatropine 2% twice a day

subconjunctival injection of triamcinolone

high-dose oral prednisone

Discussion:

This patient has acute anterior uveitis. A uveitis of recent onset is most likely to reduce vision because of associated cystoid macular edema. Treatment should begin with frequent topical corticosteroids and cycloplegia. The topical corticosteroids are very effective in reducing anterior chamber inflammation and should be tapered only when the reaction is nearly completely resolved. The cycloplegic agent reduces the photophobia and the risk of progressive posterior synechiae formation. Sub-Tenon’s injections of triamcinolone are sometimes given for cystoid macular edema or severe uveitis refractory to topical medication, but subconjunctival injections are not. It is wise to first start a course of topical corticosteroids to see whether the cystoid macular edema resolves or she is among those patients who could have a rise in intraocular pressure with periocular corticosteroids. Oral prednisone and cytotoxic agents are reserved for patients with recalcitrant, vision-threatening uveitis.

3- 15-month-old child with bilateral retinoblastoma

The pregnant mother of a 15-month-old child with bilateral retinoblastoma asks about the chances of her unborn baby also developing the condition. What is the most appropriate answer to her question?
less than 1%

6%

Further information is required to answer.

40%

Retinoblastoma is caused by a mutation of the RB1 gene, located on chromosome 13. Calculating the risk of recurrence of the disease in any individual family is complicated by many special features of its genetic transmission. Although it is a genetically recessive trait (both copies of the RB1 gene must be mutated to cause retinoblastoma), it is phenotypically dominant because of a relatively high spontaneous mutation rate of the remaining normal allele in retinal tissue of patients who have inherited only one copy of the mutant gene. The penetrance (chance of developing retinoblastoma when a mutant RB1 gene is inherited) is only about 80%. In addition, 94% of cases represent new mutations, 75% of which are somatic and not inheritable, presenting as unilateral, solitary tumors, and 25% of which are germline and potentially transmissible, presenting as bilateral, multifocal tumors. Furthermore, a small percentage of patients with unilateral, solitary tumors has germline mutations and is likely to pass the mutation on to offspring.

Because of this complexity, further information, especially additional family history and a thorough retinal exam of both parents for regressed retinoblastoma or retinoma, is required to establish the likelihood that these parents are carrying a genetically transmittable mutant RBI gene. Based on this information, the risk of recurrence can be calculated by studying published tables in consultation with a geneticist or genetic counselor. In the situation presented, assuming the retinal exam of the parents is normal, the chance of the unborn child being affected by retinoblastoma is 40% if there is a positive family history in addition to the sibling, and only 6% if no other family members are affected.

4- Severe pain and loss of vision in the right eye

نتيجة بحث الصور عن ‪closed angle glaucoma‬‏

A 62-year-old woman presents with severe pain and loss of vision in the right eye that has lasted for 3 hours. The IOP is 65 mm Hg OD and 13 mm Hg OS. There is corneal epithelial edema OD and the cornea is normal OS. Both anterior chambers appear rather shallow. There is no evidence of iris neovascularization. You have treated her with one drop each of a topical beta-adrenergic antagonist, dorzolamide (Trusopt), apraclonidine (Iopidine), and pilocarpine. One hour later the patient is substantially more comfortable, and the IOP is 16 mm Hg OD. What is the appropriate treatment of the right eye at this point?
glaucoma filtering surgery

laser peripheral iridotomy

observation to see if angle closure recurs

topical pilocarpine therapy to prevent angle closure

Discussion:

In a patient presenting with acute angle-closure glaucoma, antiglaucoma medical therapy can rapidly reduce IOP, relieve patient discomfort, clear the cornea, and possibly break the attack of acute angle closure glaucoma. Although pilocarpine might be of short-term benefit in this setting, chronic pilocarpine therapy should not be used in lieu of performing a laser peripheral iridotomy. A laser peripheral iridotomy is necessary to prevent the recurrence of angle-closure glaucoma.10 Pilocarpine would not prevent its recurrence. Performed in this acute setting, glaucoma filtering surgery would be prone to have a high complication rate and a low chance of success. If successful in this eye, filtering surgery might not be necessary and could cause chronic hypotony. If an attack of acute angle-closure glaucoma is quickly and successfully broken, the trabecular meshwork might function normally and not require either glaucoma medication or filtering surgery to maintain a normal IOP.

5- Topical anesthetic agents

In what ocular structures do topical anesthetic agents produce analgesia?
conjunctiva and cornea

conjunctiva and ciliary muscle

cornea and iris

conjunctiva and dilator muscle

Discussion:

As the name implies, topical anesthesia is just that: topical. The ocular surfaces (conjunctiva and cornea) are rendered analgesic by topically applied ocular anesthetic agents. The sensitive intraocular structures (the iris and ciliary muscle) are innervated by the long ciliary nerves, and when these structures are manipulated at surgery, pain can be induced. Pain can be caused either by direct manipulation of instrumentation (e.g., on the iris) or by simply deepening the anterior chamber with the inflow of irrigation fluid, which causes the ciliary muscle to stretch. Excellent analgesia of intraocular structures can be obtained by the instillation of intracameral anesthetic agents such as preservative-free lidocaine.

6- Two months after a car accident…

Two months after a car accident, a 65-year-old woman complains that she has had double vision ever since regaining consciousness the day after the accident. She is diagnosed with a traumatic sixth nerve palsy. If botulinum toxin is injected into the ipsilateral antagonist medial rectus, what is the most common complication that might arise?
ptosisCorrect

paradoxical contracture

induced vertical deviation

globe perforation

Discussion:

Transient ptosis is the most common complication following injection of botulinum toxin into an extraocular muscle, such as into the ipsilateral medial rectus muscle to treat acute sixth nerve palsy. This complication occurs in 10% to 15% of cases, and it is therefore important to warn the patient about the possibility prior to injection. The ptosis typically lasts 6 to 8 weeks. Some believe that having the patient sit up immediately following injection reduces the spread of the toxin to the levator complex and can reduce the incidence of this complication. Less commonly, spread of the toxin to neighboring vertical muscles might result in a vertical deviation and diplopia. In most cases this vertical deviation resolves in 6 to 8 weeks, but if it persists, surgical intervention is rarely required. Globe perforation occurs in less than 0.2% of injections. Paradoxical contracture is not a recognized complication.
How should a case of membranous, congenital nasolacrimal duct obstruction, and stenosis of both upper and lower canaliculi be managed?
bicanalicular intubation of the nasolacrimal ductCorrect

bicanalicular intubation with dacrocystorhinostomy

bicanalicular ring intubation with pigtail probe

monocanalicular intubation

Discussion:

Congenital nasolacrimal obstruction is most commonly caused by membranous obstruction of the distal nasolacrimal duct at the level of the valve of Hasner. Less common are membranous obstructions that occur within the more proximal nasolacrimal duct and less commonly still the canalicular system. While obstructions of the nasolacrimal duct are effectively treated in 97% of cases by probing alone at between 6 and 18 months of age, canalicular membranes are less likely to remain patent after probing. Consequently, probing with silastic intubation of the involved canaliculi is more likely to result in long-term patency.

In this case, both upper and lower canaliculi are involved. Consequently, a bicanalicular stent of both the canaliculi and duct are indicated. A monocanalicular stent would not address one of the two canalicular obstructions, and a pigtail probe would not stent the duct obstruction. Dacrocystorhinostomy is required only for a nasolacrimal obstruction that fails to respond to silastic intubation or is found to be bony in nature at the time of the initial probing.

7- Diagnose This: Blurred vision OU after bilateral cataract surgery

For the last 4 months, a 68-year-old man has had blurred vision OU. He has had bilateral cataract surgery. His visual acuity was 20/20 OU. His pupillary reactions were sluggish OU with no relative afferent pupillary defect. Given his fundus appearance OU shown, what additional feature of his disorder is likely to be noted on exam?
reduced color vision

metamorphopsia on Amsler grid testing

arcuate defects on visual field testing

normal IOP

Discussion:

This patient has cupping out of proportion to his optic pallor from glaucomatous optic neuropathy. Although the IOP might be within the normal range (normal tension glaucoma) the most likely finding would be an elevated IOP. Measures of central visual function including visual acuity and color vision would be expected to be normal until very late in glaucomatous optic neuropathy. Metamorphopsia is suggestive of a retinopathy and would be unexpected in glaucoma.

 8- Eye fatigue and intermittently blurred vision at near

A 44-year-old man complains of eye fatigue and intermittently blurred vision with near activities. In addition to testing distance and near visual acuities, what other parameters should be assessed?

 1-  presence of cataract

2- contrast sensitivity

3- pupil function
4- accommodative amplitude

Discussion:

The patient’s complaints are consistent with a deficiency of accommodative amplitude. With presbyopia, the accommodative response decreases due to a loss of lens elasticity, and patients often complain of eye fatigue and blurred vision at near.

Presence of a cataract would not give intermittent blurred vision and is not typically associated with eye fatigue or isolated problems with near vision.

Examining pupil function would provide information on the status of the optic nerve by checking for an afferent pupillary defect (APD). A compromised optic nerve would not usually be associated with this patient’s symptoms. Assessing pupil function might also provide an explanation for photophobia in someone with mydriasis.

Testing contrast sensitivity, for example with the Pelli-Robson chart, is usually done by spatial frequency and looks at a patient’s ability to distinguish between light and dark bands of varying size and contrast. A decrease in contrast sensitivity can be seen with numerous disorders such as

  • Corneal pathology
  • Cataracts
  • Glaucoma
  • Retinal disorders

Measuring the patient’s contrast sensitivity in the case presented here would not add any useful information that might explain his complaints.

9- Transient bilateral visual loss after position changes

For the last 9 days, a 67-year-old man noted transient bilateral visual loss that was precipitated by changes in position and worsened when arising. Three weeks ago, he also began to experience right-sided headaches. He has cirrhosis related to chronic hepatitis B infection. When initially evaluated he was found to have bilateral optic disc edema with multiple cotton-wool spots and an abnormal head CT scan as shown. What would you recommend?

  1- neurosurgical consultationCorrect

2- lumbar puncture

3- optic nerve sheath fenestration

4- Westergren erythrocyte sedimentation rate

Discussion:

The axial CT of the head shows a hypodense lesion over the right hemisphere from a right subdural hematoma, perhaps aggravated by a coagulopathy related to his cirrhosis. There is also a right-to-left shift of intracranial contents. Prompt neurosurgical consultation should be recommended to determine whether surgical evacuation of the hematoma is warranted. His optic-disc edema is probably from papilledema due to raised intracranial pressure rather than from ischemia related to giant-cell arteritis. A Westergren erythrocyte sedimentation rate might be elevated from his other diseases, but would not be helpful. Because there is a mass effect from the subdural hematoma, a lumbar puncture might precipitate brain herniation. Optic nerve sheath fenestration might reduce optic-disc edema, but does not address the primary life-threatening problem.

10- Consenting a patient for panretinal photocoagulation

Image courtesy of Harry W. Flynn, Jr, MD.

When consenting a patient for panretinal photocoagulation, what common potential complications should be discussed?
transient myopiaCorrect

chronic glaucoma

improved dark adaptation

resolution of macular edema

Discussion:

Transient myopia is commonly expected after panretinal photocoagulation, which results from swelling of the ciliary body and forward shift of the lens–iris diaphragm. Photocoagulation of the peripheral retina worsens dark adaptation, sometimes permanently. Macular edema often worsens following panretinal photocoagulation. For this reason, concomitant or antecedent focal macular laser is done. The data from the Diabetic Retinopathy Study showed that untreated eyes with proliferative diabetic retinopathy were twice as likely to have elevated IOP than that of treated eyes (2.1% versus 1.1%). Untreated high-risk proliferative retinopathy can proceed into development of neovascular glaucoma.

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