The fourth in our new series- taking you through a detailed case history and describing the key principles of care before offering a take home message.
For more than a week, a 74-year-old man has had diminished vision in his left eye. He reports that the problem started acutely with a sensation of flashing lights in the affected eye, followed by the presence of dark floaters for several days. He initially had minimal vision loss in the lateral (temporal) field, but with each day the loss has become more profound and central; it now significantly impedes his ability to read and perform activities of daily living. He denies headaches or other neurological symptoms either before or during this episode.
The patient was relatively healthy for his age. He had had mild hypertension for about 10 years, well controlled with lisinopril, 10 mg per day. He had no history of coronary disease or diabetes mellitus. He saw an optician regularly and had a complete examination four months earlier, with no change in his eyeglass prescription.
Heart rate was 76 beats per minute, regular and his blood pressure was, 110/68. His eyes appeared normal, without inflammation, and cranial nerves are intact. Fundoscopy was deferred until consultation with an ophthalmologist. The rest of the physical findings were normal.
A complete full blood count and biochemistry screen were normal. Total cholesterol level was 4.5mmol/L, with a high-density lipoprotein cholesterol level of 1.6mmol/L. Triglyceride level was 2.5mmol/L.
What is the most likely cause of this patient's visual symptoms?
A. Scintillating scotoma
B. Amaurosis fugax
C. Retinal detachment
D. Age-related macular degeneration
Correct answer: C.
This patient experienced an acute unilateral ocular syndrome followed by subacute deterioration in vision. On the basis of the clinical findings, primary retinal detachment choice C) is the most likely diagnosis.
Epidemiology and symptoms of primary retinal detachment
Primary retinal detachment is extremely common and age-dependent event. Roughly 10% of cases are in persons younger than 60 years; 27% are in persons between the ages of 60 and 70 years; and 63% are in persons older than 70 years.1 This patient's symptoms are classic: flashing lights and floaters followed by a progressive loss of visual field.
Pathophysiology of primary retinal detachment
Lifelong liquefaction of the vitreous is responsible for floaters, which result from debris being able to move in the more liquid vitreous. This more liquid vitreous may also dissect into atrophic holes or tears in the retina; the herniated fluid can then force the retina into the subretinal space, thereby detaching the neural retina from the posterior structures of the eye (the pigmented epithelium and the choroid). This separation distorts the visual anatomy and can cause further retinal tears in areas of strong vitreoretinal adhesion. If detachment progresses to include the macula, profound loss in visual acuity occurs. (Nonmacular detachments produce lesser degrees of vision loss.)
Treatment of primary retinal detachment
Retinal detachment is an ocular emergency. Most studies have shown that post-treatment visual acuity is inversely proportional to the time between onset of symptoms and repair. The most cited studies indicate that one week is the critical time window for repair; results are inferior when surgical repair is not performed within seven days.1,2
A variety of surgical techniques are available, including pneumatic retinopexy, scleral buckling, and vitrectomy.1 Repair can usually be performed in the ophthalmologist's office. Determining the most appropriate technique depends on the particular findings in a given case and is beyond the scope of this discussion.
Age-related macular degeneration
This potentially blinding disease affects, at least to some degree, as many as one-third of persons older than 75 years. Unlike the syndrome in this patient, age-related macular degeneration (choice D) has an insidious rather than an abrupt onset; it develops gradually and painlessly.3
This condition is characterized by an acute partial loss of vision often described as "a shade covering one eye." However, the vision loss is transient, usually lasting only seconds to minutes before reversing. Amaurosis fugax (choice B) is caused by ischaemia in the ophthalmic artery, typically resulting from carotid atherosclerosis. Episodes are often premonitions of more serious cerebrovascular events.4 This patient's history of progressive loss of vision over a period of days does not fit this diagnosis.
This is another acute-onset ocular syndrome. Scintillating scotoma (choice A) is characterized by the presence of a flickering spot, followed by a spreading arc of flashing lights that prevents vision within the scotoma. Its pathophysiology puts it within the spectrum of migraine syndromes (it is a type of acephalgic migraine). As with amaurosis fugax—but again, unlike the syndrome in this man—the symptoms of scintillating scotoma are transient; they almost always pass within 60 minutes, and usually within 5 to 20 minutes.
Outcome of this case
An ophthalmologist was consulted, and fundoscopy with pupil dilation confirmed a retinal detachment involving the macula, with tears at superior fundus positions. Pneumatic retinopexy was performed in the office, with good results. The patient was advised that subsequent procedures may be required and that careful monitoring is mandatory.
This piece was written by Ronald N Rubin, MD and first appeared in our US sister publication Consultant Live http://www.consultantlive.com/home but has been reviewed for UK relevance.
Primary retinal detachment – characterised by perception of flashing lights and floaters followed by progressive visual field loss – is an ocular emergency. For optimal results, repair must be performed within one week of symptom onset.