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Friday, September 26, 2008

Mcqs opthalmology

Try these challenging set of Mcqs in Opthalmology.(detailed explanation present)


Question.

1. A one-year-old child having leucokoria was detected to be having a unilateral, large retinoblastoma filling half the globe. Current therapy would involve:

1. Enucleation.

2. Chemotherapy followed by local dyes.

3. Direct Laser ablation using photo dynamic cryotherapy.

4. Scleral radiotherapy followed by chemotherapy.

Answer

1. Enucleation.

Discussion

Enucleation is indicated in unilateral and bilateral Retinoblastomas involving more than half of the globe

Explanation

1. Enucleation is done as the Retinoblastoma is filling half the globe.

2. Chemotherapy followed by local dyes will not be effective.

3. Direct Laser ablation using photodynamic cryotherapy will not be effective.

4. Scleral radiotherapy followed by chemotherapy will not be effective.

Tips

Management of Tumors of Eye with regard to the size

  • Small Tumors
    • Laser Photocoagulation or transpupillary thermotherapy
    • Cryotherapy
  • Medium Tumours
    • Brachytherapy : Tumor less than 12 mm in diameter and less than 6 mm in thickness
    • Chemotherapy with Carboplastin, Vincristine, Etoposide
    • External Beam Irradiation
  • Large Tumors
    • Enucleation
    • Chemotherapy
Try more of these Mcqs ,please continue.


Question.

2. A 20-year-old man complains of difficulty in reading the newspaper with his right eye. Three weeks after sustaining a gunshot injury to his left eye. The most likely diagnosis is:

1. Macular edema.

2. Sympathetic ophthalmia.

3. Optic nerve avulsion.

4. Delayed vitreous hemorrhage.

Answer

2. Sympathetic ophthalmia.

Discussion

Sympathetic ophthalmia refers to the development of panuveitis in the opposite “sympathizing” eye following penetrating trauma to the primary or exciting eye, thus resulting in Granulamatous uveitis. Dalen Fuch’s Granules are seen.

Explanation

1. Macular edema doesn’t will not cause difficulty in the opposite eye..

2. Sympathetic ophthalmia is the correct diagnosis.

3. Optic nerve avulsion will not cause difficulty in the opposite eye.

4. Delayed vitreous hemorrhage will not cause difficulty in the opposite eye.

Comments

  • Predisposing Factors
    • Injury
    • Incarceration of Iris : Wound in the region of Ciliary body(Dangerous Zone)
    • Infection Absent
  • Treatment is
    • Steroids
    • Cycloplegics
    • Immunosuppression

Tips

  • First Symptom is Loss of Accommodation
  • First Sign is Presence of Keratin Precipitates

Question.

3. A recurrent bilateral conjunctivitis occurring with the onset of hot weather in young boys with symptoms of burning, itching, and lacrimation with polygonal raised areas in the palpebral conjunctiva is:

1. Trachoma.

2. Phlyctenular conjunctivitis.

3. Mucopurulent conjunctivitis.

4. Vernal kerato conjunctivitis.

Answer

4. Vernal kerato conjunctivitis.

Discussion

Vernal Conjunctivitis

  • Called as Spring Catarrh
  • Bilateral
  • Exogenous Allergen
  • Itching
  • Ropy Discharge
  • Maxwell Lyon Sign
  • Palpebral Conjunctiva has Cobble Stone Appearance (polygonal)
  • Bulbar Conjunctiva has Horner Trantas Spots
  • Cornea has Pseudogerantoxon with Cupid Bow outline

Explanation

1. Trachoma has follicles.

2. Phlyctenular conjunctivitis is unilateral and itching is not marked.

3. Mucopurulent conjunctivitis may not be recurrent.

4. Vernal kerato conjunctivitis is the correct choice.

Comments

The history and signs point classically to Vernal Conjunctivitis

Question.

4. A child has got a congenital cataract involving the visual axis, which was detected by the parents right at birth. This child should be operated.

1. Immediately.

2. At 2 months of age.

3. At 1 year of age when the globe becomes normal sized.

4. After 4 year when entire ocular and orbital growth become normal.

Answer

1. Immediately.

Discussion

Treatment is not required in Cataract until the vision is considerably impaired. Visually significant cataract should be operated immediately

Comments

2 to 4 months of age is the critical period for developing fixation reflex.

Lamellar cataracts are operated After 4 years when entire ocular and orbital growth become normal.

Question.

5. A lady wants LASIK surgery for her daughter. She asks for your opinion. All the following things are suitable for performing LASIK except:

1. Myopia of 4 Diopters.

2. Age of 15 years.

3. Stable refraction for 1 year.

4. Corneal thickness of 600 microns.

Answer

2. Age of 15 years.

Discussion

Laser Assisted in-situ keratomileusis (LASIK)

INDICATIONS

  1. Approved range for myopic correction is – 0.5 to –14.00 diopters (-2 to –12 D; Parsons’), with up to 5 diopters of astigmatism
  2. Residual stromal bed thickness should be at least 250 mm (i.e. total corneal thickness of 550-600mm)
  3. Hyperopic corrections have been approved for +4.00

CONTRAINDICATIONS

  1. Unstable refractive error.
  2. Age less than 21 years.
  3. Active collagen vascular disease (especially in the presence of iritis or scleritis).
  4. Pregnancy.
  5. Presence of a pacemaker.
  6. Any ongoing active inflammation of the external eye (eg, conjunctivitis, severe dry eye).
  7. Refractive error outside the range of laser correction.
  8. Keratoconus

PATIENT SELECTION FOR LASIK (preoperative workup)

  1. Contact lens wear should be discontinued prior to the examination
    • 3 days for soft contact lens wear
    • 2 weeks for rigid gas permeable lenses.
  2. A complete eye examination
    • Manifest and cycloplegic refraction
    • Slit lamp examination
    • Dilated fundus examination –Indirect Ophthalmoscopy
    • Corneal topography
    • An estimate of scotopic pupil size is helpful in screening candidates that may be at risk for postoperative glare

PROCEDURE

  1. Paint, drape, place speculum.
  2. A suction ring placed on the eyeball elevates IOP to about 60 mmHg (temporary blackout of vision occurs).
  3. The microkeratome advances and creates an epithelial flap, which is hinged usually nasally.
  4. The flap is lifted and laser ablation of stroma done.

EXCIMER LASER is used.

  • Leave behind residual corneal thickness of at least 250 microns.
  • Irrigate bed with saline and close the flap. No sutures. It sticks by itself.
  • Use antibiotics and steroid drops for about 1 week.

ENHANCEMENTS

  • Enhancement LASIK (i.e. repeat procedure) can be performed but usually after 3 months of table refraction.

SUPER VISION

  • Wavefront technology in LASIK aims to correct all aberrations of the eye to give vision beyond 6/6 – super vision.

Explanation

1. Myopia of 4 Diopters is an indication.

2. Age of 15 years is a contraindication. In fact Age less than 21 is contraindication.

3. Stable refraction for 1 year is needed.

4. Corneal thickness of 600 microns is needed.

Question.

6. The operation of plication of inferior lid retractors is indicated in:

1. Senile ectropion.

2. Senile entropion.

3. Cicatricial entropion.

4. Paralytic entropion.

Answer

2. Senile entropion.

Discussion

Entropion is Inward rotation of turning of the lid margin towards the globe. It can be Congenital, Spastic, Cicatrical or Senile Entropion

  1. Congenital Entropion
    • Rare
    • Present since birth
    • Management
      • Plastic Reconstruction
  2. Spastic Entropion
    • Due to spasm of Orbicularis Oculi
    • Management
      • Treatment of Cause of Spasm
      • Botulinum Toxin
  3. Cicatrical Entropion
    • Most common in Upper Lid
    • Due to
      • Trachoma,
      • Burns,
      • Pemphigus
      • Steven Johnson Syndrome
    • Management
      • Modified Burrows
      • Joesche Arlt’s
      • Modified Ketessey
      • Resection of Skin, Muscle and Tarsus
  4. Senile Entropion
    • Most common in Lower Lid
    • Seen in elderly
    • Management
      • Jones, Reeh and Wobig Operation - Tucking or Plication of Inferior Lid retractors
      • Modified Wheelers
      • Weiss
      • Blick

Explanation

  1. Plastic operations are done for Senile ectropion. For spastic ectropion the cause is treated
  2. Senile entropion is managed with Jones, Reeh and Wobig Operation - Tucking or Plication of Inferior Lid retractors, Modified Wheelers, Weiss, Blick operations.
  3. Cicatricial entropion is managed with Modified Burrows, Joesche Arlt's, Modified Ketessey, Resection of Skin, Muscle and Tarsus
  4. Paralytic entropion is managed with plastic surgeris.

Question.

7. A patient is on follow-up with you after enucleation of a painful blind eye. After enucleation of the eyball, a proper sized artifical prosthetic eye is advised after a postoperative period of:

1. About 10 days

2. About 20 days.

3. 6-8 weeks.

4. 12-24 weeks.

Answer

3. 6-8 weeks.

Discussion

An artificial eye of plastic should not be worn less than 2 weeks after excision. A small eye may be worn for an hour or two a day till the conjunctiva becomes used to the foreign body. Eight or nine weeks after the operation a full sized eye may be worn; a plastic eye need only be taken and washed once a week

Explanation

1. Anything Should not worn About 10 days

2. A small eye is worn for an hour or two from about 20 days.

3. A PROPER SIZED ARTIFICIAL PROSTHETIC EYE is advised after 6-8 weeks.

4. 12-24 weeks is too long a time.

Comments

Even though most of the books recommend initiation of the prosthesis after 3 weeks, According to Parson, small prosthesis are worn after 3 weeks following surgery……. And a proper sized prosthesis is worn after 8 weeks…..Since our question also has the word proper, we go for choice 3

Tips

Be careful to the words, “full”, “proper”, “definite” etc in the question paper

Question.

8. In a patient with AIDS chorioretinitis is typically caused by:

1. Cytomegalvirus.

2. Toxoplasma gondii.

3. Cryptococcus neoformans.

4. Histoplasma capsulatum.

Answer

1. Cytomegalvirus.

Discussion

  • CMV retinitis is an important cause of blindness in immunocompromised patients, particularly patients with advanced AIDS.
  • One of the most devastating consequences of HIV infection is CMV retinitis.
  • Patients at high risk of CMV retinitis (CD4+ T cell count <100/uL) should undergo an ophthalmologic examination every 3 to 6 months.
  • The majority of cases of CMV retinitis occur in patients with a CD4+ T cell count <50/uL.
  • Prior to the availability of HAART, this CMV reactivation syndrome was seen in 25 to 30% of patients with AIDS.
  • CMV retinitis usually presents as a painless, progressive loss of vision. Patients may also complain of blurred vision, "floaters," and scintillations.
  • The disease is usually bilateral, affecting one eye more than the other.
  • CMV infection of the retina results in a necrotic inflammatory process, and the visual loss that develops is irreversible.
  • Intravitreal injections of cidofovir are generally avoided due to the increased risk of uveitis and hypotony.

Explanation

1. Cytomegalvirus causes chorioretinitis in 30 % of HIV Cases. (Harrison)

2. Chorioretinitis due to toxoplasmosis can be seen alone or, more commonly, in association with CNS toxoplasmosis, but is less common than CMV Chorioretinitis.

3. Cryptococcus neoformans causes meningitis.

4. Histoplasma capsulatum affects the lungs.

Comments

  • CMV retinitis may be complicated by rhegmatogenous retinal detachment.
  • Therapy for CMV retinitis consists of intravenous ganciclovir or foscarnet, with cidofovir as an alternative. Combination therapy with ganciclovir and foscarnet has been shown to be slightly more effective than either ganciclovir or foscarnet alone in the patient with relapsed CMV retinitis.

Tips

  • P. carinii can cause a lesion of the choroid that may be detected as an incidental finding on ophthalmologic examination. These lesions are typically bilateral, are from half to twice the disc diameter in size, and appear as slightly elevated yellow-white plaques.

Question.

9. Fasanella Servat operation is specifically indicated in:

1 Congenital ptosis.

2. Steroid induced ptosis.

3. Myasthenia gravis.

4. Horner’s syndrome.

Answer

4. Horner’s syndrome.

Discussion

  • Fasanella Servan Operation is a Surgical Procedure for management of Ptosis.
  • The upper border of Tarsus is excised with the lower border of Muller’s Muscle and Overlying conjunctiva
  • It is done is cases where the levator function is adequate and atleast 10 mm and ptosis is not more than 2 mm
  • Indicated in
    • Horner’s Syndrome
    • Cases of Mild Congenital Ptosis

Explanation

1. Congenital ptosis, if mild can be managed by Fasanella Serva operation.

2. Steroid induced ptosis.

3. Myasthenia gravis needs medical management or Thymectomy.

4. Fasanella Servan Operation is best suited for Horner’s syndrome.

Comments

Though Fasanella Servan Operation is also done for few cases of Congenital, the fact that it can be done for MOST cases of Horners syndrome make that a preferred choice as the question says SPECIFICALLY

Question.

10. Type IV hypersensitivity to Mycobacterium tuberculosis antigen may manifest as:

1. Iridocylitis.

2. Polyarteritis nodosa.

3. Phlyctenular conjunctivitis.

4. Giant cell arteritis.

Answer

3. Phlyctenular conjunctivitis.

Discussion

Phlyctenular conjunctivitis

  • Delayed hypersensitivity
  • To endogenous microbial protein
    • Tubercular
    • Staphylococcal
  • Unilateral
  • Irritation, Discomfort and Reflex Lacrimation
  • Phlycten at Limbus is characteristic
  • Mononuclear infiltration in a triangular area
  • Corneal Ulcers are
    • Fascicular Ulcer
    • Ring Ulcer
    • Scrofulous Ulcer
  • Treated with Steroids

Explanation

Self explanatory

Comments

Though iridocyclitis also can be produced by hypersensitivity, since this is a Classical description for Phylcten, we go for this answer

Tips

Phylcten is commonly due to TB, but TB commonly causes Iridocyclitis

Question.

11. Vortex vein invasion is commonly seen in:

1. Retinoblastoma.

2. Malignant melanoma.

3. Optic nerve gliomas.

4. Medullo-epitheliomas.

Answer

2. Malignant melanoma.

1. Retinoblastoma.

Discussion

Malignant Melanoma of choroids invades the Vortex Veins leading to Glaucoma

Explanation

1. Retinoblastoma also invades Vortex vaein, but less commonly than Malignant Melanoma.

2. Vortex vein invasion is commonly seen in Malignant melanoma.

3. Vortex vein invasion is not commonly seen in Optic nerve gliomas.

4. Vortex vein invasion is not commonly seen in Medullo-epitheliomas.

Question.

12. A patient using contact lens develops corneal infection. Laboratory diagnosis of acanthamoeba keratitis was established. The following is the best drug for treatment:

1. Propamidine.

2. Neosporine.

3. Ketoconazole

4. Polyhexamethylene biguanide.

Answer

1. Propamidine.

4. Polyhexamethylene biguanide.

Reference

  • Basak 2nd Edition Page 121
    • Propamidine.
  • Kanski 4th Edition Page 108
    • Polyhexamethylene biguanide.
  • Nema 4th Edition Page 147
    • Propamidine.
  • Harrison 15th Edition Chapter 213
    • Propamidine.
  • Many Premier Ophthal Institutes use
    • Polyhexamethylene biguanide.
  • Nelson -
    • Amphotericin B in combination with
    • rifampin,
    • sulphadiazine,
    • chloramphenicol, or
    • ketoconazole were the components of the successful regimens.
  • Oxford Textbook of Medicine
    • Amphotericin B or
    • flucytosine will be the initial choice for systemic use.
    • Eye lesions have sometimes responded to local
    • propamidine and
    • neomycin, but the latter is not cysticidal;
    • combinations of topical propamidine
      • with chlorhexidine or
      • polyhexamethylene have recently been successful.

Discussion

Acanthameoba

  • Acanthamoeba has only a cyst and trophozoite form, of which only the trophozoite form is invasive.
  • Free living
  • Oppurtunistic
  • Cases of Acanthamoeba keratitis have usually followed
    • incidents of corneal trauma involving
    • flushing with contaminated water, or
    • in contact lens wearers whose lenses have been contaminated with Acanthamoeba.
  • Diagnosis by Calcoflour white

Explanation

1. Propamidine can be used.

2. Neomycin is used. No idea regarding Neosporine.

3. Ketocanazole also is used

4. Polyhexamethylene biguanide can be used.

Comments

PHB is superior to Propamidine as it is cationic in nature and penetrates the cornea better.

Any how …………..You decide !!!

But one thing is confirmed. The best antiseptics are Chlorhexidine and Hydrogen Peroxide

Tips

Naegleria, Acanthamoeba, and Balamuthia are small, free-living amebas that cause human meningoencephalitis. Amebic meningoencephalitis has two distinct clinical presentations. The more common presentation is that of an acute, usually fatal infection of the central nervous system (CNS) occurring in previously healthy children and young adults; granulomatous amebic meningoencephalitis usually occurs in immunocompromised individuals.The other related organism are Naeg

Question.

13. A vitreous aspirate has been collected in an emergency at 9 pm what advice you like to give to the staff on duty regarding the overnight storage of the sample.

1. The sample should be kept at 4° C.

2. The sample should be incubated at 37°C.

3. The sample should be refrigerated deep freezer.

4. The sample should be refrigerated for the initial 3 hours and then incubated at 37°C.

Answer

2. The sample should be incubated at 37°C.

Discussion

Vitreous Sample collected in Emergency is best stored at 37°C - the body temperature where as the cornea is best stored/ transported in 4°C

Explanation

1. 4°C is needed when Cornea is stored.

2. The sample should be incubated at 37°C.

3. The sample should not be refrigerated in deep freezer, because the cells would lyse.

4. The sample should not be refrigerated for the initial 3 hours because the cells would lyse .


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