GLAUCOMA GRAND ROUNDS

Childhood Trauma and the Recalcitrant IOP

J. James Thimons, O.D.

A 38-year-old black female presented for a consult regarding elevated IOP in the left eye following cataract surgery. Her history revealed that the cataract resulted from a blunt trauma sustained during an athletic event when she was a child. She said her vision before the injury was normal. She had mild hypertension, treated with exercise and diet. Her family’s medical and ocular histories were negative. For the past seven months, this patient has been treated with Timoptic (timolol maleate) and Diamox (acetazolamide).

Physical Examination
Uncorrected visual acuities were 20/20 in the right eye, 20/400 in the left. Pinhole showed improvement in the left eye to 20/200. External examination demonstrated a normal pupil shape and response in the right eye, but the left eye was irregular and responded poorly. I noted a 2+ afferent pupillary defect in the left eye. Extraocular movements were full without diplopia, and confrontation fields were normal.

Applanation tensions were 16mm Hg in the right eye, 42mm Hg in the left at 10 a.m. A slit lamp exam revealed clear corneas with an irregular vitreous face and mild clouding of the optical pathway. Gonioscopy of the right eye showed ciliary body 360º with no abnormalities. The left eye demonstrated several areas of peripheral anterior synechiae with some zones of normal angle structure.

A dilated fundus exam showed a cup-to-disc ratio of 0.4 O.D. and 0.9 O.S., with generalized loss of nerve fiber layer in the left eye. Additionally, there was a chorioretinal scar in the left posterior pole with fibrotic formation.

It was difficult to administer a visual field test because of the patient’s poor acuity, but she showed a normal 24-2 SITA standard automated perimetry in the right eye and significant loss of visual function in the left, with both arcuate bundle and nasal step involvement.

Discussion
This patient demonstrates a somewhat typical cataract presentation following a trauma. In patients who have the lens removed—especially in childhood—it’s not atypical to have residual secondary capsular formation or haziness of the anterior vitreous face.

These patients frequently have pressure elevations that occur any time following cataract removal. Their IOPs typically don’t respond as well to topical therapy as open angle glaucoma, and the progression of nerve damage can be significant in a relatively short time frame.

Even though she has been on significant therapy, this patient shows extremely high IOPs. I decided to discontinue the Diamox for several reasons: her young age, the potential for toxicity with chronic use, and the poor control of her IOP.

To allow adequate time for clearance, I had her return in three days, at which time the pressure was unchanged.

Normally, a pressure greater than 40mm Hg demands immediate steps to lower it. However, given the patient’s age,the chronic nature of the disease and questions about drug efficacy, we needed to determine what—if any—effect each of the therapies is having on controlling her IOP.

The lack of a change in this patient’s IOP is evidence that Diamox, the oral carbonic anhydrase inhibitor (CAI), is not effective and should be discontinued. Further, with the introduction of topical agents, CAIs are no longer a viable long-term therapy.

The next step was to determine the efficacy of Timoptic, the beta-blocker. Because beta-blockers have prolonged effects and take up to several months to wash out, the easiest way to assess their function is to have the patient stop the beta-blocking drops for one day and then return to the office.

At that visit, measure the patient’s pressure and then instill a drop of the beta blocker. Once the drug takes effect—in two to three hours—measure the patient’s pressure again. A lower IOP typically tells you if the agent is working.

While this is not a perfect system, it’s very useful in confirming the efficacy of this drug therapy. Ob-viously, the lack of a significant response is not necessarily an indication of the drug being ineffective.

After being off the beta-blocker for 24 hours, this patient had IOPs of 19mm Hg in the right eye and 48mm Hg in the left. In-office treatment lowered the pressure to 16mm Hg in the right eye and 41mm Hg in the left within two hours, dem-onstrating that the beta blocker was effective.

Considering her history of cataract surgery and trauma, I started her on Alphagan (brimonidine) twice a day in the left eye and scheduled her to return in two weeks. At that time, her IOP had decreased to 35mm in the left eye. But there were other complicating factors: The patient said the medication made her light-headed. Also, she had no health insurance and said the drops were expensive.

Aphakic and pseudophakic patients are occasionally good candidates for a cholinergic agent. Typically, phospholine iodide 0.0625 percent twice a day is a good starting dosage. While this drug is rarely used in typical chronic open angle glaucoma patients, it’s an effective and inexpensive alternative in patients who have had cataract extraction.

I started her on this dosage, and asked her to return in two days. At that visit, her pressures at 10 a.m. were 15mm Hg in the right eye, 22mm Hg in the left. I gave her instructions on punctal occlusion and asked her to return in two months.

The goal in this patient is a 50-60 percent initial pressure reduction. With a two-drug regimen, this patient’s IOP dropped from 48mm Hg to 22mm Hg. While a pressure in the teens would be preferable, this is a good starting point for long-term management.

Followup
This patient has been under treatment for more than two years and has had relatively good success, even considering her occasional episodes of non-compliance. Her visual fields are stable, and the optic nerve is unchanged from the stereophotos taken at her initial visit. I am following her every three months, with visual fields twice a year.

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