Latanoprost

A young child at risk for glaucoma presents a treatment challenge. See what this O.D. did.

The definition of glaucoma has evolved over the past 20 years and the most widely accepted definition is also the simplest: Glaucoma is an optic neuropathy. Glaucomatous optic neuropathy occurs because of the presence and prevalence of many factors in an individual. It's this multifactorial aspect of the disease that sometimes makes it difficult to diagnose, which is especially true if the patient is young, as in this case.

A pediatric presentation

By all accounts, J.T. was a normal eight-and-a-half-year-old boy. He was a well-spoken and polite third-grader who was in my office "just to be checked" for the possibility of glaucoma. Though it may seem far-fetched that he could have glaucoma, let me explain that I'm treating his mother (43), his aunt (46) and his grandmother (72) for glaucoma. J.T.'s family tells me that he has numerous other cousins who also have glaucoma (thus the concern for J.T.).

J.T. was already wearing glasses, through which he saw 20/25 OD and 20/25 OS. He told me that his eyes were "just fine" and that he was seeing well with and without his eyeglasses. He said his eyes didn't hurt or itch or tear and he didn't have discomfort of any type. He was taking montelukast sodium (Singulair) and used an inhaler as needed for asthma.

Taking a closer look

Up to this point, my exam revealed essentially a normal set of eyes for this essentially normal kid. I found no strabismus or amblyopia and J.T.'s pupils were 7 mm in size and briskly reactive to light OU. A refraction of -0.75-1.00 × 180 OD and -1.00-0.75 × 180 OS improved his VA to 20/20 OU. He had normal color vision and 40 seconds of stereopsis. The slit lamp exam was also entirely normal. Notably, he had wide open anterior chamber angles, Grade 4 OU using the Von Herrick method. His IOP was measured at 24 mmHg OD and 25 mmHg OS with a Tonopen. I also used the Goldmann tonometer and got a reading of 23 mmHg in each eye at 3:15p.m.

I dilated J.T.'s pupils and carefully examined the optic nerve heads with a 78D lens. At this point, the little boy's aura of complete normalcy evaporated. What first caught my attention was that he had a medium-sized optic nerve head with a large cup-to-disc (c/d) ratio. I judged it to be .87.8 OD and OS with a pink neuroretinal rim OU. The rims did appear somewhat thinner temporally in each eye. J.T. also had an anomalous corkscrew-type vessel on the surface of his right optic nerve head (ONH) at about 5:00. The cups were deep and the rims rather sharp in their appearance. I saw no lamina cribrosa in the base of either ONH. The remainder of his retinal and macular grounds were normal.

Reason to keep testing

Under other circumstances, I likely would have had a long talk with J.T.'s parents about glaucoma and discharged him with a one-year recall. But given the strong family history and his elevated IOP, I felt it was prudent to try to gather some more data. I scheduled J.T. to return in one month for a visual field test and for a repeat IOP measurement. His mother brought him back and his IOP was 28 mmHg OD, 29 mmHg OS at 9:30a.m.

We performed a central 24 degree visual field on him, but the results weren't valid. The analysis showed 13 false positive responses OD and 20 false positives OS. Even though the visual fields test didn't reveal any usable data, the IOP measurement did. The IOP was 5 mm and 6 mm higher that morning. As such, J.T. has a diurnal curve of at least 6 mm Hg. I still wasn't convinced that he needed treatment for glaucoma. I once again dismissed him and scheduled an appointment for three months.

At that visit, I used Talia Technology's RTA (retinal thickness analyzer), which provides me with objective data about the integrity of the ONH and retinal nerve fiber layer (RNFL). Before I dilated J.T.'s pupils to run the test, I measured his IOP at 16 mmHg OD and OS. I directed the RTA to scan both the posterior pole thickness and optic disk topography. The right eye showed a mildly depressed overall thickness to the macula.

Though there wasn't any statistically significant attenuation, there clearly wasn't a thick, uniform hill of vision OD. The disk topography OD revealed an unequal temporal-superior-nasal-inferior-temporal (TSNIT) curve with four out of six focal quadrants identified as being outside normal limits (Fig Ia). The RTA result OS showed more dramatic attenuation of the posterior pole thickness (Fig Ib) and a severely depressed TSNIT curve.

A classic conundrum

The objective data from the RTA pointed toward a weak optic nerve classically seen in glaucoma. But I still questioned whether I could justify starting the now nine-year-old J.T. on glaucoma medications, especially given that his most recent IOP was 16 mmHg. I once again had a long discussion with J.T. and his mom. She was familiar with glaucoma and understood the potential for future visual loss, and so I trusted her to bring J.T. back for regular follow up. Therefore, I didn't initiate treatment at that time, but once again asked to see J.T. in three months - again in the morning. I measured his IOP on two separate occasions, the first at ll:15a.m., where the IOP was 22 mmHg and 23 mmHg OD and OS respectively. Two weeks later, at 8:15a.m., the IOP was 26 mmHg OD, 29 mmHg OS. A second attempt at a visual field resulted in another unreliable analysis.

Choosing a course of action

I once again asked myself whether J.T.'s findings warranted treatment. He was a nine-year-old African-American boy who had a strong family history of glaucoma. He had suspicious-looking ONH, much like those of his mother, whom I was already treating for glaucoma. The RTA data showed an elevated suspicion for the RNFL thinning and ONH damage, yet half of his IOP measurements were well within the normal range.

Still, he had a huge diurnal IOP curve 10 mmHg OD and 13 mmHg OS. I took another close look at his ONH and saw neuroretinal rims that were much thinner than 99% of kids his age whom I've examined. I thought of his mother, his aunt and his grandmother and I decided that the reasons to treat outweighed the reasons to not treat. I prescribed latanoprost (Xalatan) OU q.h.s. and I set two target IOPs (12 mmHg as the target for the afternoon pressure and 16 mmHg to 17 mmHg as the target IOP in the a.m. peak pressure time).

Success at last

J.T. is now about one year into his treatment. I've switched him to travoprost (Travatan) OU q.h.s., which has achieved a consistent IOP of 16 mmHg in the a.m. and 14 mmHg in the p.m. In J.T.'s case, travoprost was much more effective at flattening out the diurnal curve than latanoprost. J.T. will hopefully have a long life ahead of him. My goal is to keep his IOP low enough to prevent any further damage to a fragile ONH. Hopefully I can help to keep him seeing for the next 70 years and beyond.

with Eric Schmidt, O.D.

by Eric Schmidt, O.D.

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

Copyright Boucher Communications, Inc. Mar 2005
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