CLINICAL CHALLENGES
An Ounce of Prevention
Incorporate new technology into your regular diagnostic regimen and you'll help patients.

As diligent eye doctors, we preach and practice preventive care to our patients. We espouse annual eye exams and stress proper compliance with contact lens wear. In patients who have age-related macular degeneration (ARMD), we recommend anti-oxidant therapy and hopefully teach our patients to use the Amsler grid regularly. None of us really knows how much of this talk falls on deaf ears and how much of it patients actually implement. We do know, however, that when patients follow through with these prescribed regimens, they can help to avert potentially devastating ocular consequences.

Meet Ms. D

Ms. D was the classic ARMD patient. She had light hair, blue eyes and was in her 80s. She also had a family history of ARMD (or so we think). Her mother had lost significant vision from "something other than cataracts" when she was in her 70s. Ms. D first came to my practice in 2000 because of decreased vision from cataracts. At that exam, her visual acuity (VA) was 20/40 OD and 20/50 OS.

I diagnosed her with cataracts, and also noted that she had a mild amount of soft drusen in the foveal region of each eye. There was no apparent thickening of the macula OU and no intra- or subretinal hemorrhages. There was no metamorphopsia noted on Amsler grid testing. Ms. D underwent cataract extraction OS and did well. Her VA improved to 20/25 OS and she was reading happily again. I released her from our care and instructed her on how to use an Amsler grid. (I suggested that she use the grid at least four times each week and scheduled her for a six-month follow-up visit.)

3D papillary thickness map of foveal region showing focal area of elevation.

Ms. D returns

Five months later, Ms. D returned to my office concerned about the vision in her left eye. She said that for the past few weeks, her vision had become progressively more blurred until her central vision had become completely black. I asked her whether she had noticed any earlier changes on the Amsler grid and she responded that she hadn't been looking at it as I instructed.

Upon examination, I noticed a large area of active subretinal bleeding and significant macular edema. Unfortunately, the fluorescein angiogram showed a minimally classic subretinal membrane and even though a retinal specialist performed laser therapy with verteporfin, the patient's vision was reduced to 10/800 because of a macular scar. The VA in her OD however was still 20/40.

I once again had a serious discussion with Ms. D about ARMD and the need for continued diligence on both of our parts. We re-instructed her on the importance of now daily Amsler grid screenings for her good eye and told her that if she noticed any change whatsoever in her vision or on the grid to come to the office immediately. I also put her on an "AREDS (Age-Related Eye Disease Study) formula" vitamin and talked to her about some dietary considerations. In addition, I set her up for regular six-month evaluations.

Cause for alarm

Ms. D's ARMD remained stable for two years. Her cataract OD increased in size and was removed without incident. Her vision improved to 20/25-2 OD and remained at 10/800 OS. Then, one day last winter, Ms. D came in ahead of her scheduled appointment time. She said she was concerned because her vision didn't seem quite as good as it had been. She said that she wasn't seeing a black spot and and that she hadn't noticed any distortion on the Amsler grid, which she looked at every day. As she said, rather sheepishly, "I may just be paranoid, but I'd rather be safe than sorry." Ms. D assured me that she was taking her ocular vitamin daily as prescribed. She was also taking a prescribed baby aspirin but no other medications.

	Cross-section of retina showing focal accumulation of subretinal fluid.

Searching for an answer

Her VA measured 20/30+2 OD and 10/800 OS. There was no afferent pupil defect and both pupils were round, equal and reactive. My slit lamp exam showed that nothing had changed on Ms. D's anterior segments. Her corneas, conjunctivae and lids were free of pathology and the posterior chamber intraocular lenses (IOL) were centered with no posterior capsule opacification OU.

Before I dilated her, I had Ms. D look at the Amsler grid with her right eye which, indeed, was normal. She reported seeing no metamorphopsia or scotomas OD. I used a 78D lens to carefully examine her right retina. There was a mild accumulation of soft drusen as I had seen before, but in addition I noticed a change from the previous exams. Immediately inferior to the fovea, I observed a small area of focal thickening. There were no retinal hemorrhages associated with this and there didn't appear to be any associated subretinal hemorrhages. Nonetheless, this area of thickening was in a position that could cause the visual disturbance that Ms. D described.

To get a better idea of the magnitude of this thickening, I ordered a retinal thickness analysis, which confirmed that the area I saw was indeed thickened compared to the rest of Ms. D's retina (see figure on page 26). The deviation probability plot showed that focal thickening was statistically and significantly abnormal (see figure above). A cross-section analysis showed that there was fluid associated with this area, making it likely that a subretinal neovascular membrane (SRNVM) was causing the elevation. This being the case, prompt intervention was necessary to preserve her good vision in the OD in light of her previous bleeding episode OS.

PDT to the rescue

A retinal specialist saw Ms. D that afternoon and a fluorescein angiogram (IVFA) confirmed a small area of subretinal bleeding secondary to a choroidal neovascular membrane. Fortunately, the lesion wasn't subfoveal and was rather well demarcated, so the retinal specialist was able to initiate treatment.

The retinal specialist performed photodynamic therapy (PDT) using verteporfin dye and a dye laser to seal the leak and eradicate the membrane. The treatment was successful. The edema and bleeding completely resolved and because of the small area of treatment, there was no scotoma left to interfere with Ms. D's vision.

Managing Ms. D

It has now been one year since Ms. D had PDT. She still retains a VA of 20/30-2 OD and 10/800 OS and has shown no regrowth of the SRNVM; the retinal thickness analysis shows almost complete flattening of the previously elevated area. I see Ms. D every four months and she rigorously observes her Amsler grid. I've also discussed with her the importance of eating leafy green vegetables and a lot of tuna. She's keenly aware of the need to return to my office immediately if she notices any subjective change in her vision.

Know what's important

This case illustrates many things for optometrists. First, that it's essential to properly educate all of our ARMD patients. In Ms. D's case, if I hadn't continually educated her on how to manage her condition, she probably wouldn't have come to the office until her SRNVM had spread to a much larger area.

Second, all eyecare practitioners must understand the new treatment opportunities for ARMD and when patients are candidates for such treatment, as well as when they aren't. Also, as this case illustrates, technology is helpful for early detecting and mapping of macular diseases such as ARMD. Technologies such as retinal thickness analysis aren't just for glaucoma. They're also useful for detecting macular disease and you should incorporate them into your regular diagnostic regimen for these conditions.

Contributing Editor Eric Schmidt, O.D., is director of the Bladen Eye Center in Elizabethtown, N.C. E-mail him at schmidtyvision@bellsouth.net.