Timoptic

CLINICAL CHALLENGES

Tailoring glaucoma therapy for a patient with one sighted eye.

We all know the importance of tailoring open angle glaucoma treatment to the individual. Some patients require more aggressive therapy because of age, the optic nerve head condition and other risk factors. But does a person with just one usable eye need more aggressive therapy because of this condition? This case will help answer that question.

Reviewing the case

An O.D. friend of mine in New Jersey had been treating Mrs. Meyer for glaucoma for 2 years and felt that her condition was fairly stable. My friend told me that Mrs. Meyer was moving to my area, and she hoped that I would assume her care. I jumped at the opportunity. My friend sent me a summary of Mrs. Meyer's case and copies of her visual fields (VFs).

Two months later, I met Mrs. Jo Meyer. She was 70 years old and besides glaucoma, she had hypertension, for which she took labetalol hydrochloride (Normodyne) and terazosin Hcl (Hytrin). She'd had diabetes for 6 years and controlled her condition with 30 units of insulin in the morning and 20 units in the evening. Her insulin levels were normally 110 mg/dl to 130 mg/dl.

Examining Mrs. Meyer

Mrs. Meyer's ocular status troubled me. She was blind OD from a traumatic injury suffered at the age of 5, which left her with no light perception in that eye. Her visual acuity (VA) OS was 20/30 with a moderate compound myopic astigmatism.

Mrs. Meyer used timolol maleate 0.5% (Timoptic) b.i.d. OS and dipivefin hydrochloride (Propine) 0.1 % b.i.d. OS. I first met her in 1995, when treatment options were limited. The VFs showed a minimal loss of sensitivity with no focal defects OS. During her history, Mrs. Meyer informed me that her brother was being treated for glaucoma.

Mrs. Meyer's pupil OD was barely visible but non-reactive. The OS pupil was 5 mm and reactive. I measured a 50 prism diopter constant right exotropia. Slit lamp exam revealed a scar on the inferior third of the cornea OD. I saw a small area of band keratopathy temporally in that eye. Uveal pigment from the injury almost occluded the pupil, obscuring my view of the dense 4+ nuclear sclerotic cataract.

The OS showed a better picture, with grade 3 anterior chamber angles as measured by the Von Herrick method. The OS had mild 1+ nuclear sclerosis and a 1+ posterior subcapsular cataract. I dilated Mrs. Meyer's pupils but couldn't view the right optic nerve because of the lens and corneal opacities.

The optic nerve OS showed a large cup-to-disk (C/D) ratio that I estimated to be .8/.8. I saw laminar dots in the base of the cup, and nasalization of the vessels. A moderate ring of peripapillary atrophy circled the optic nerve head 360 degrees. Also, I saw two small micro-aneurysms inferior to the foveal avascular zone OS. Her pre-dilated intraocular pressure (IOP) was 10 mm Hg OD, 25 mm Hg OS. It rose to 27 mm Hg OS after dilation.

Mounting concerns

Mrs. Meyer was at risk for progression of her disease, despite the seemingly good VFs. Rather than starting pilocarpine Hcl (Pilocar) or an oral carbonic anhydrase inhibitor (CAI), the only remaining available agents then, I recommended an argon laser trabeculoplasty (ALT).

Three weeks later, after gonioscopy revealed a grade 4 angle 360 degrees OS, an ALT was delivered to the temporal 180 degrees. The eye responded; IOP dropped to and stabilized at 21 mm Hg. But despite this 20% decrease in IOP, I felt the pressure was still too high. My target of 17 mm Hg hadn't yet been reached. I tried apraclonidine Hcl (Iopidine) t.i.d. OS and oral methazolamide (Neptazene) 50 mg b.i.d., without effect on the IOP.

Ten months after I first saw her, Mrs. Meyer's VFs were still normal. I still thought that given her large C/D ratio, peripapillary atrophy, multiple risk factors and monocular condition, the IOP needed to be lower. A surgeon performed a second ALT on the nasal 180 degrees in my office. It had no effect on the IOP

Serial VFs showed a mild worsening in Bjerrum's zone superiorly (see image, page 62 ), but was it enough to warrant surgical intervention? The IOP remained at around 21 mm Hg without surgery until October of 1996, when latanoprost (Xalatan) and brimonidine tartrate (Alphagan) became available on the market.

During the next 2 years I successfully adjusted Mrs. Meyer's drops. While she was taking timolol maleate 0.5% OS b.i.d., brimonidine tartrate OS b.i.d. and latanoprost OS qhs, Mrs. Meyer's TOP reduced to 16 mm Hg OS. It remained there into 1999. Her visual field remained relatively normal too, and her optic nerve head topography was unchanged. But her VA had steadily decreased to 20/70 because of a worsening nuclear sclerotic and posterior subcapsular cataract OS. The cataract needed to be removed.

It was a "20/70" cataract, dense enough to cause the 20/70 VA. Extracting it would probably improve her vision to 20/30. But would she benefit from a trabeculectomy and, if so, should it be performed with the cataract extraction or separately at a later date? The answer lay partly in the scientific literature and partly in clinical experience.

And the answer is.

The Advanced Glaucoma Intervention Study (AGIS) offers a guidepost for cases like this. AGIS sought to determine whether ALT or trabeculectomy was as effective as maximum medical therapy in preserving a glaucoma patient's VF

It showed that a trabeculectomy provides better pressure reduction and reduction of the number of topical medications. Further, African-Americans benefit from ALT followed by trabeculectomy; white Americans benefit from a trabeculectomy first and ALT after. This study also recommended considering both ALT and trabeculectomy as initial therapy for some patients.

Mrs. Meyer and Me

In this case, I thought "the less surgery, the better." If one procedure could lower the IOP, reduce Mrs. Meyer's need for drops and improve her vision, it would be my first choice. A combined cataract extraction/trabeculectomy provides this option. I also felt that with a clear cornea cataract extraction, the trabeculectomy would be more successful.

After I explained the options to Mrs. Meyer and detailed the greater risk given her one usable eye, she opted for the combined procedure.

I referred her to a fellowship-- trained glaucoma specialist who also performed clear cornea cataract extractions. In the summer of 1999, she had the triple procedure. Three months later, she saw 20/30 uncorrected and 20/25- with a prescription of -0.50-1.00 x 85. Her IOP was 10 to 12 mm Hg using only brimonidine tartrate OS b.i.d.

Soon after, Mrs. Meyer moved back to New Jersey. I arranged for her former O.D. to continue the care she'd started 7 years earlier. I believe Mrs. Meyer will do well.

CLINICAL PEARLS

This case presented in 1995 when therapeutic options were much more limited. If this case presented now, what would I do differently?

Initial therapy would probably be a prostaglandin, brimonidine or a beta-blocker qd. An oral carbonic anhydrase inhibitor would probably be unnecessary today. Also, an argon laser trabeculoplasty (ALT) in lieu of drops may not be needed.

How many medications should you prescribe before prescribing an ALT or trabeculectomy? With the success of today's procedures, I consider two drops to be the maximum. But some patients will need the procedure after three medications and others will need it after one. Judge each case independently.

I'd recommend that a glaucoma specialist perform the trabeculectomy.

Follow the surgical recommendations in the Advanced Glaucoma Intervention Study. For African-Americans, have the ALT performed 360 degrees first, followed by a trabeculectomy if needed. A trabeculectomy is recommended initially for white Americans.

By Eric Schmidt, O.D.

Contibuting Editor Eric Schmidt, O.D., is diretor of the Bladen Eye Center in Elizabethtown, N.C. E-mail him at Kenziekate@aol.com

Copyright Boucher Communications, Inc. Jan 2002
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