Opthalmology Pre Test

1.  Answer E

Age related (senile) macular degeneration is a major cause of legal blindness in patients over 65 years of age.  The clinical features include drusen (degenerative changes in the pigment epithelium and in bruch's membrane) and formulation of a subretinal neovascular membrane.  This membrane causes distortion in the central visual field, associated with decreased visual acuity.  The distortion is frequently the first symptom and strongly suggests age-related macular degeneration.  Decreased peripheral vision is not associated with macular degeneration.  Sudden painless loss of vision can be associated with a retinal disease such as occlusion of the central retinal artery.  Severe ocular pain and photophobia strongly suggest iritis.  Severe ocular pain associated with a marked decrease in visual acuity suggests acute angle closure glaucoma.

2. Answer C

Strabismus is misalignment of the eyes.  Normal eye alignment is essential to allow the normal development of binocularity and stereopsis.

Accommodative esotropia is caused by an abnormality of the near reflex.  Convergence of the eyes is controlled reflexively, along with focus for near vision.  This normal integration is necessary to maintain eye alignment and to focus on targets are various distances.  The amount of convergence is increased by refractive errors requiring a greater than normal amount of accommodation and by inherently increased reflexive convergence.  This excessive convergence causes patients to cross their eyes when converging.  Treatment for accommodative esotropia most often consists of lenses to correct refractive errors.

The reversal of amblyopia occurs most quickly and completely in patients treated at the earliest ages.  Therefore, the earlier detection and treatment occur, the better the outcome.

3. Answer E

It is helpful to decide whether patients with visual loss have a disease process involving structure of the globe or of the optic nerve and its central radiations.  If loss of vision is secondary to an optic nerve lesion, there will be an afferent papillary defect on the symptomatic side, demonstrated by the swinging light test.  This failure to sustain papillary constriction is sometimes referred to as the Marcus Gunn pupil sign.  Visual loss of functional cause or that related to ocular disease rarely affects the papillary light reflex.  In elderly patients the cause may often be infarction of the optic nerve due to temporal arteritis, arteriosclerosis, or emboli.  In young adults optic neuritis is often associated with multiple sclerosis.

4. Answer D

The retinal findings shown are consistent with central retinal artery occlusion.  The painless, unilateral, sudden loss of vision over a period of seconds may be caused by thrombosis, embolism, or vasculitis.  Acute narrow-angle glaucoma is an abrupt, painful, monocular loss of vision often associated with a "red eye" which will lead to blindness if not treated.  In persons with optic neuritis, funduscopy reveals a blurred disc and no cherry red spot.  Occlusion of the central retinal vein causes unilateral, painless loss of vision, but the retina will show engorged vessels and hemorrhages. 

5. Answer A

Nonexudative age-related macular degeneration is characterized by variable degrees of atrophy and degeneration of the outer retina, retinal pigment epithelium, Bruch's membrane, and choriocapillaries.  Of the opththalmoscopically visible changes in the retinal pigment epithelium and Bruch's membrane, drusen are the most typical.  Drusen are discrete, round, yellow-white deposits of variable size beneath the pigment epithelium and are scattered throughout the macula and posterior pole.  Age-related macular degeneration is the leading cause of permanent blindness in the elderly.

6. Answer: A

Refractive surgeries have become commonplace, and are used to correct myopia and hyperopia.  The LASIK procedure creates a corneal flap and ablates part of the corneal stroma with no sutures.  RK and PRK involve radial incisions to change the shape of the cornea.  LTK uses a laser to shrink the cornea to change the shape.  With ICR a plastic ring is placed into the cornea to change its shape.

7. Answer A

Phorias are intermittent eye crossings; tropias are fixed crossings; exo refers to lateral, while eso refers to medial; and hyper refers to abnormalities in the vertical plane.  Accommodative esotropia occurs in a child who is significantly farsighted.  Pseudostrabismus refers to an apparent esotropia that occurs in an infant with a wide nasal bridge and prominent epicanthal folds.  The clue that the eyes are normal is they symmetric placement of the corneal light reflex.

8. Answer E

The earliest finding in glaucoma is an asymptomatic elevation of intraocular pressure.  Prevention of insidious and often undetected vision loss requires an active effort to detect the disease in its early, asymptomatic stage.  The vast majority of patients do not have ocular inflammation, pain, or halos, even with the loss of significant peripheral vision.

9. Answer C

Amblyopia is subnormal visual acuity in one or both eyes despite correction of any significant refractive error.  The sooner it is diagnosed, the better the prognosis for a functional and cosmetic cure.  The two most common causes of amblyopia are strabismus (malalignment) and anisometropia, which is due to unequal refractive errors.  Under binocular conditions, a child with strabismic amblyopia will preferentially fixate with the better eye.  The child needs prompt referral to an ophthalmologist for evaluation of refractive error and ophthalmoscopically visible abnormalities and for treatment of amblyopia.

Strabismus (squint) affects about 3% of children.  Transient strabismus may be normal in the first 4 months of life, during the period of macular development.  Any transient deviation after 4 months of age or constant strabismus at any age requires prompt referral to an ophthalmologist.

Some children may give the appearance of crossed eyes because of epicanthal folds (pseudostrabismus), but their vision can be proven to be normal by an equal central corneal light reflex.

20. Answer A

Patients with retinal tears complain of photopsia and floaters.  In retinal artery occlusion the patient relates a history of painless catastrophic visual loss occurring over a period of seconds; antecedent transient  visual  loss (amaurosis fugax) may be reported.  In retinal vein occlusion, the patient presents with sudden painless loss of vision.  Most patients who develop this are over 50 years of age, and more than half have associated cardiovascular disease.

Iritis causes photophobia; intraocular pressure is not elevated, the pupil is constricted, and the cornea is usually not edematous.  Endophthalmitis is a vitreous abscess which may occur following penetrating ocular trauma.

21.  Answer D

Keratoconjunctivitis sicca and xerostomia are most characteristic of Sjogren's syndrome.  However, Sjogren's syndrome may be secondary to other autoimmune rheumatic diseases such as rheumatoid arthritis, systemic lupus erythemtosus, or scleroderma.

22.   Answers: T; F; F; T; T

Diabetic retinopathy is the leading cause of blindness in Americans under the age of 60.  Its prevalence is directly related to the duration of the diabetes mellitus.  Laser photocoagulation can reduce vision loss from proliferative retinopathy. Aspirin does not prevent proliferative retinopathy, nor does it increase the risk of hemorrhage.