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Why Do Maculae Have Disturbances?

Why Do Maculae Have Disturbances?

And, what will it take to restore vision to the patient’s left eye?

Mark T. Dunbar, O.D.

A 69-year-old Haitian female presented complaining of decreased vision in the right eye for approximately four months. The vision in her fellow eye had been severely diminished since 1996. She had no prior history of ocular surgery or trauma.

The patient was diagnosed with hypertension and hyperlipidemia in 1994, and diabetes in 1996. Her medicines included hydrochlorothiozide, Accupril (quinapril, Parke-Davis) and Glucophage (metformin, Bristol-Myers Squibb).

Best-corrected visual acuity was 20/30 O.D. and 20/400 O.S. Confrontation visual fields were full to careful finger counting O.U. Pupils were equally round and reactive with a 2+ afferent pupillary defect O.S. Ocular motility testing was normal.
The anterior segment was unremarkable O.U. IOP measured 24mm Hg O.U.
A dilated fundus exam revealed large cup-to-disc ratios in both eyes that appeared glaucomatous in nature; the left eye was worse than the right. Macular changes are shown below.

The dilated fundus exam (O.D. left, O.S. right) revealed large cup-to-disc ratios in both eyes, and the patient’s eyes exhibited these macular changes.

We also performed optical coherence tomography (OCT) of the macula O.U., as shown on the next page.

Take the Retina Quiz
1. What does the OCT of the right eye demonstrate?
a. Lamellar hole.
b. Intraretinal cysts.
c. Foveal detachment of the neurosensory retina.
d. Vitreomacular traction with a foveal pseudocyst.
 
2. What is the correct diagnosis in the right eye?
a. Epiretinal membrane.
b. Stage I macular hole.
c. Cystoid macular edema.
d. Pigment epithelial detachment.

3. Which of these statements best describes the vitreous in the patient’s right eye?
a. Complete posterior vitreous detachment (PVD).
b. Shrinkage and tangential traction of the posterior vitreous.
c. Detachment of the posterior hyaloid with anterior-posterior traction.
d. Perifoveal vitreous detachment.

4. What is the diagnosis of the macular lesion in the left eye?
a. Stage II macular hole.
b. Stage III macular hole with complete PVD.
c. Stage III macular hole with incomplete PVD.
d. Cystoid macular edema with a ruptured cyst.

5. What is the best treatment for the macular lesions?
a. Observation O.U.
b. Vitrectomy O.D., observation O.S.
c. Observation O.D., vitrectomy O.S.
d. Vitrectomy O.U.

For answers, click here.

Discussion
The unusual presentation in the right eye represents the early stages of a full-thickness macular hole. This patient has a stage I macular hole, according to the progressive stages of macular hole formation J. Donald M. Gass, M.D., had described.1

However, this patient’s macular hole is atypical in presentation. The typical stage I macular hole has a yellow spot or ring in the center of the fovea. This patient’s eye does not. Instead, we see more of a radial spoke-like appearance at the fovea.
So how do you know that this is a stage I macular hole? The images from optical coherence tomography offer some clues.
Optical coherence tomography scans (O.D. top, O.S. bottom) show these vitreoretinal interface changes.

OCT can image retinal structures in vivo with a resolution of 10µ-17µ, then produce cross-sectional images of the retina. This helps us differentiate the anatomic layers within the retina and measure retinal thickness.

In this case, OCT demonstrates an incomplete detachment of the posterior vitreous around the macula. There is no separation of the posterior hyaloid interface at the fovea.

This “perifoveal” vitreous detachment results in traction at the fovea, where the vitreous is still adherent. This traction, in turn, leads to the development of a full-thickness macular hole if the vitreous does not completely and spontaneously detach on its own. This occurs in about 50% of patients.1

OCT also led to the discovery of a foveal “pseudocyst,” in the early stages of macular hole formation. This pseudocyst is a large, optically empty space within the retina. The photoreceptors, which remain attached to the retinal pigment epithelium, are relatively unaffected in the early stages of macular hole formation. This explains why our patient had such good acuity despite a foveal thickness of 520µ.

This macular pseudocyst presumably results from intraretinal splitting at the fovea, where the oblique course of Henle’s fiber layer and Mueller’s cells provide a weaker infrastructure against the vitreous traction. The pseudocyst likely results from the vitreomacular traction, which itself results from a perifoveal posterior hyaloid detachment, as the OCT scans demonstrate.2,3

With progression, foveolar thickening may lead to subsequent hole formation. The macular hole may gradually enlarge, often in a can-opener fashion, within weeks or months. The operculum of the hole may remain attached to one edge of the hole, or it may separate and become suspended on the surface of the posterior hyaloid membrane immediately in front of the hole.

The OCT of our patient’s left eye shows a full-thickness macular hole. However, there is still a tuft of virteomacular traction involving the attached operculum, resulting in disruption of the foveal architecture. Small intraretinal cysts also appear on both sides of the hole. Based on the clinical presentation and OCT image, this patient’s left eye has a stage II macular hole.

We referred this patient to a retinal specialist to determine whether vitrectomy in the left eye was necessary. We elected to observe the right eye for now, to see if she will spontaneously develop a complete PVD on her own. If this eye also progresses to a stage II hole, we can refer her for vitrectomy; there would still be an excellent visual prognosis. We also started her on Lumigan (bimatoprost, Allergan) O.U. for IOP control.

This case was written by Christa McCleary, O.D., an optometric resident at Bascom Palmer Eye Institute in Miami.
 
1. Gass JDM. Stereoscopic Atlas of Macular Diseases: Diagnosis and Treatment. Vol. 2. St. Louis: C.V. Mosby Company, 1987:671-94.
2. Haouchine B, Massin P, Gaudric A. Foveal pseudocyst as the first step in macular hole formation. Ophthalmology 2001 Jan;108(1):15-22.
3. Azzolini C, Fatelli F, Brancato R. Correlation between optical coherence tomography data and biomicroscopic interpretation of idiopathic macular hole. Am J Ophthalmol 2001 Sep;132(3):348-55.

Vol. No: 139:12Issue: 12/15/2002

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