Clinical Challenges
The "Hole" Truth
Diagnosing and treating a macular hole.
Clinical Challenges with Eric Schmidt, O.D.

One of our primary tasks is recognizing early signs of ocular morbidity and prescribing the best therapy to preserve our patients' visual acuities. It's incumbent upon us to remain current with new medications and surgical interventions from which our patients may benefit. In many cases, early surgical or therapeutic intervention greatly decreases the chance of serious vision loss. Here's an example from which you may benefit.

THE CASE: Mr. Lewis is a 72-year-old retired logger whom I've been treating for the past 7 years. When I "inherited" him in 1994 from a doctor who retired, he was using pilocarpine nitrate 2% (Pilagan) OU, q.i.d.; dipivefrin HCl 0.1% (Propine) OU, b.i.d.; and timolol maleate 0.5% (Timoptic) OU, b.i.d. for primary open-angle glaucoma (POAG). Therapy for his POAG was initiated in 1987.

In 1994, when I first saw Mr. Lewis, his visual acuity (VA) was 20/50 OD and 20/60 OS. His optic disks revealed a cup-to-disk ratio of .6/.7 OU. Initial intraocular pressure (IOP) was 15 mm Hg OD, 16 mm Hg OS on the three medications, and his visual fields showed superior arcuate scotomas denser OS than OD.

Mr. Lewis had miotic 3-mm pupils from the pilocarpine nitrate, which somewhat limited his VA. He also had 2+ nuclear sclerotic cataracts, which also contributed to his decreased VA.

When Mr. Lewis had both cataracts removed in 1995, his vision improved to 20/25 in each eye. Almost as importantly, after the cataracts were removed, his anterior chambers deepened, allowing for better aqueous outflow. This enabled me to discon-
tinue the dipivefrin and the pilocarpine and to maintain his IOP at less than 14 mm Hg using only timolol hemihydrate 0.5% (Betimol) OU, b.i.d.

Mr. Lewis's IOP remained at our target of 15 mm Hg until 1999, when it rose to 19 mm Hg and 20 mm Hg on three occasions. Close inspection of his optic disks showed further inferior regression of the neuroretinal rim in both eyes and a corresponding worsening of the visual field. His POAG was progressing. He probably had developed tachyphylaxis to the beta-blocker. I told him to stop the timolol hemihydrate; in its place I prescribed latanoprost 0.005% (Xalatan) OU, q.h.s. The latanoprost reduced his IOP to the low teens.

Dodging a bullet

Things seemed stable until Mr. Lewis came in for a routine POAG follow-up visit 5 months after I put him on latanoprost. He had no complaints and specifically said that he hadn't noticed any change in his vision.

However, upon checking his vision, the VA had decreased to 20/60 OS. It remained at 20/25 OD. I saw no posterior capsular opacification of either eye. But when I examined his retina, I noticed a very subtle elevation to the macula OS, which I described as a stage 1 macular hole.

The examination revealed no evidence of vitreoretinal or epiretinal traction. I had Mr. Lewis stop the latanoprost immediately for fear that it may have been precipitating cystoid macular edema or retinal thickening. I also placed him on brimonidine tartrate 0.2% (Alphagan) OU, b.i.d., and asked him to return in 3 weeks. At that time, his VA had improved to 20/30 OS and his IOP measured 12 mm Hg OD, 14 mm Hg OS. His macula appeared flat without a visible cyst or hole OS.

I felt that the hole had resolved itself, so I asked Mr. Lewis to continue the brimonidine tartrate OU b.i.d. and scheduled him for a 2-month visual field exam and follow-up.

At that visit, Mr. Lewis once again had no visual complaints and claimed to be using the brimonidine tartrate as prescribed. His VA, however, was severely reduced to 20/200 OS (it re-
mained at 20/25 OD). IOP remained good at 12 mm Hg OD, 11 mm Hg OS.

My exam revealed a well-circumscribed but small, full-thickness macular hole OS (see photo on page 98). Red-free photography and fluorescein angiography further accentuated its full thickness and revealed a surrounding subretinal cuff of fluid (see photo at right).

The "hole" story

A macular hole is a full-thickness opening of the retina in the foveal area resulting in loss of central vision. Idiopathic macular holes aren't uncommon, typically affecting women older than 70 years and 0.33% of all people 

older than age 55. Though the pathogenesis is still not completely clear, macular holes result when the relationship between the vitreous and the inner retinal surface is disrupted.

J. Donald Gass, M.D., has postulated that macular holes develop not from antero-posterior traction, as commonly thought, but rather from tangential traction that occurs when the posterior vitreous contracts.

Clinically, a full-thickness hole is best seen using a condensing lens and a biomicroscope. It classically appears as a darker red spot in the fovea with complete loss of overlying retinal tissue in that circumscribed area. A fluid cuff commonly encircles the hole. This cuff is whitish and represents a shallow serous retinal detach-ment along the margin of the macular hole.

A slit lamp finding classic of a macular hole is the positive Watzke-Allen sign. When you focus a narrow slit beam on the retina and then pass it over the hole, you'll see a discontinuity of the slit beam. The portion of the beam coincident with the hole will bend posteriorly, away from you. Occasionally, you'll also see yellow drusen-like deposits in the floor of the hole.

The vitreous overlying the hole is key to understanding this disease. Typically, you'll see an operculum adherent to the posterior vitreous. Usually, the vitreous base is completely detached from the macula. However, occasionally the vitreous remains attached. This is called a vitreofoveal separation. It's crucial to examine the other "normal" eye for a posterior vitreous detachment (PVD). If a PVD doesn't exist in the normal eye, the chances of a macular hole forming there rise to as high as 20%.

The VA is severely decreased with macular holes because the foveal area is devoid of photoreceptors. Thus, you'll find a negative central scotoma, as well as VA of 20/200 or worse.

Staging the holes

Dr. Gass described the following four stages of macular hole formation:

• Stage 1 is a foveal detachment clinically marked by the appearance of a yellow spot and loss of foveal depression. Stage 1 macular holes spontaneously resolve up to 33% of the time, especially if a PVD is present. They can progress to Stage 2 over a period of weeks to months.
• A Stage 2 hole is a small, early, full-thickness hole. Vision decreases to the 20/70 range. As the vitreous shrinks further, the hole widens.
• At Stage 3, the widened hole produces severe loss of VA.
• Stage 4 holes develop when the vitreous finally separates completely from the fovea.

Treating the holes

Stage 2 and Stage 3 holes are especially responsive to retinal surgery. In a macular hole repair, the retinal surgeon first peels the epiretinal membrane to eliminate further traction. He then removes the vitreous and replaces it with a gas that remains in the eye for at least 1 month until it dissipates. These surgeries are quite successful and the improvement in VA can be astounding.

The end of the story

Because Mr. Lewis had a Stage 3 macular hole, I arranged for him to have a prompt macular hole repair. This surgery went well. Now, 1 year later, his VA has stabilized at 20/40 OS. Mr. Lewis does have a complete PVD, OD, which minimizes his chance of developing a hole in that macula. I'll continue to watch for that as I treat his glaucoma in the future.

It's key for us to recognize the onset of macular holes quickly, and to understand the likelihood of fellow eye involvement. Prompt surgical referral is a must. 

Contributing Editor Eric Schmidt, O.D., is director of the Bladen Eye Center in Elizabethtown, N.C. You can reach him by e-mail at KENZIEKATE@aol.com.