RETINA QUIZ

Asymptomatic Patient Exhibits
Unilateral Subretinal Nodules

by Mark T. Dunbar, O.D

A 40-year-old white, myopic female presented for a routine eye exam. She said she'd been myopic her whole life and wanted to try contact lenses. Her ocular and medical history was otherwise unremarkable.  

1a, 1b. Subtle RPE changes were scattered throughout the posterior pole in each eye (O.D. at left, O.S. at right). 

Best-corrected visual acuity was 20/25 O.D. and 20/20 O.S. with approximately an -8.00D myopic-astigmatic correction in each eye. Confrontation fields were full to careful finger counting O.U. The pupils were equally round and reactive, with no afferent pupillary defect. Amsler grid testing showed subtle central metamorphopsia O.D. and was normal OS.  Anterior segment examination was normal in both eyes. 

The dilated fundus exam showed healthy optic nerves with good rim color and perfusion O.U. There were subtle RPE changes in the posterior pole of both eyes. A small, localized area of subretinal fluid was present in the macula of the right eye. There was no subretinal fluid in the macula of the left eye. The peripheral retina was unremarkable in each eye. The fundus photos and fluorescein angiograms are available for your review.

    Quiz
     1. What's causing the subretinal fluid in the right eye?
    a. Choroidal neovascular membrane.
    b. Neurosensory retinal detachment.
    c. Retinal pigment epithelial detachment.   
    d. Cystoid macular edema.

    2. Why does this patient have these peculiar fundus changes throughout the posterior pole?
    a. Age-related macular degeneration.
    b. Basal laminar drusen.     
    c. Pseudoxanthoma elasticum.
    d. Fundus albipunctatus.

    3. How is the fluorescein staining pattern often described in this condition?
    a. Peau d'orange.
    b. Stars-in-the-sky.   
    c. Salt-and-pepper.
    d. White-on-black.

    4. How should this patient be managed?
    a. Observation.   
    b. Laser photocoagulation.
    c. Photodynamic therapy.
    d. Submacular surgery.

Discussion
This patient has basal laminar drusen, sometimes called cuticular drusen. These represent nodular thickenings of the basement membrane of the RPE. These are distinguished from the exudative drusen seen in age-related macular degeneration, which result from focal detachments of a normal-thickness basement membrane.

2a, 2b. Fluorescein staining showed much more extensive pathology than seen on clinical observation (O.D. at left, O.S. at right). Note the focal area of hyperfluorescence in the center of the macula of the right eye.

Basal laminar drusen are typically seen in early adulthood and occur with equal frequency among whites, blacks and Latinos. They appear as discretely round, slightly raised, yellow, subretinal nodules. Initially they may be randomly scattered in the macular area of young adults. They become more numerous as time goes on. Basal laminar drusen are usually grouped in clusters of 15-20, often arranged in a tightly knit pattern, giving the entire macula and posterior pole an orange-peel appearance.  

Basal laminar drusen are seen more easily on fluorescein angiography than on clinical examination. That was the case with this patient. Basal laminar drusen often give the fundus a "stars-in-the-sky" or "milky way" appearance.  The drusen fluoresce discretely during the early arteriovenous phase, fade from view earlier than the exudative drusen seen in AMD, and show less intense staining than the latter. 

Patients beyond age 50 are susceptible to developing superimposed, exudative drusen in the center of the macula.1 These lesions can vary in size and are more likely to occur in whites. Our patient probably developed exudative drusen, which then led to the development of a small pigment epithelial detachment.

Some patients may get a yellow serous exudative detachment that looks identical to the vitelliform lesions seen in Best's vitelliform dystrophy or pattern dystrophy. Many clinicians mistaken the fluorescein stain pattern of these lesions for choroidal neovascularization.

Since there was no obvious choroidal neovascular membrane present in our patient, no treatment was indicated; just observation. We could recommend antioxidants. But there's still no conclusive evidence that antioxidants really help. Current clinical trials may establish a clear benefit with this form of long-term management.

We gave this patient a home Amsler grid with instructions on how to use it, and asked her to return if she notices any changes on the grid.

1. Gass JDM. Stereoscopic Atlas of Macular Disease: Diagnosis and Treatment. 4th edition. St Louis: C.V. Mosby, 1997.

Answers: 1, c; 2, b; 3, b; 4, a.

 
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