GLAUCOMA GRAND ROUNDS

When Field Loss Hints at Malignant Disease

by J. James Thimons, O.D.

A 57-year-old white male presented with bilateral elevated IOP and visual field loss in the left eye. Other than the need for corrective lenses for distance and near, the patient was asymptomatic. His medical and ocular histories were unremarkable, as were his family's.

Exam findings.
The patient appeared healthy and with no physical abnormality. Extraocular motilities were full and smooth. Confron-tation visual fields were full to finger-counting. Pupil testing showed 4/4/2+3/-MG. Except for the acuity correction, bilateral external and internal ocular examinations were unremarkable.

Applanation tensions were 32mm Hg O.D., 31mm Hg O.S. at 9 a.m. Gonioscopy revealed ciliary body 360 degrees bilaterally with minimal pigmentation of the trabecular meshwork. Cup-to-disc ratio was 0.2 in each eye, with healthy neuroretinal rim tissue and posterior pole. Both mid and far periphery were within normal limits and evidenced a normal vascular pattern with no anatomic abnormalities.

Visual field 24-2-SITA testing showed a loss in the inferonasal quadrant of the left eye, which was consistent with the screening performed by the primary-care practitioner. Right eye was within limits.

Discussion.
This patient is atypical of the traditional glaucoma patient. He is relatively younger, white and has no family ocular history or medical history to support this diagnosis. More importantly, the cup-to-disc ratio is normal, which is inconsistent with the patient's visual field presentation.

While glaucoma can present with a wide variety of clinical manifestations, one of the fundamental principles of glaucoma diagnosis is that each of the clinical elements—ophthalmoscopy, visual fields, intraocular pressure, etc.—must be consistent with the others to produce a reasonable explanation for the disease.

While the non-ophthalmic risk factors are all relatively low in this patient, it's still possible that a younger white male could develop the disease in the absence of family history or secondary contributing issues. What is puzzling, however, is his normal cup-to-disc ratio.

The patient's bilaterally elevated IOP further compounds this clinical picture. A high IOP by itself typically wouldn't be sufficient to produce the degree of visual field change this patient has experienced without also contributing to optic nerve head pathology. That's why our discussion centered on the reason for the field loss, and the fact that there might very well be two separate diseases present: the first being an elevated IOP with initial diagnosis of ocular hypertension, and the second being some form of optic neuropathy unrelated to the IOP.

Treatment.
The goal pressure is in the low 20s in the non-involved eye, and slightly less in the eye with the field abnormality. I placed the patient on Alphagan (brimonidine) twice a day in the left eye. I chose this drug not only for its pressure-lowering component, but also because of its optic nerve protection.

I referred the patient to his primary-care physician for a complete physical exam, chest X-ray and CBC with differential, sedimentation rate and cholesterol/triglyceride levels.

When the patient returned two weeks later, his IOPs were still high, 30mm Hg O.D., 29mm Hg O.S. at 10 a.m. He admitted he had not been using the Alphagan as directed. I then reinstituted him on topical Alphagan in a monocular trial. When he returned for his follow-up exam, his pressure had dropped to the low 20s, and I instituted the Alphagan therapy in both eyes.

The patient further advised me that the chest X-ray showed multiple lung lesions, and that an oncologist was evaluating him. His clinical presentation indicated that it was quite possible the underlying systemic disease was causing the field loss, and that simultaneous dual disease presentation was indeed probable.

I advised the oncologist of the patient's visual field results relative to his IOP, and he concurred that the pa-tient's MRI should include serial sections of the optic nerve and chiasm.

One week later, the MRI results showed an undefined abnormality near the optic nerve, which is being further evaluated. I am following this patient monthly until a final diagnosis has been completed, and am providing his oncologist with any information relative to visual changes or a long-term management plan.

Glaucoma patients often have a higher incidence of other ophthalmic problems and underlying systemic disease. During the course of disease management, be aware that other diseases might arise that can trigger visual symptoms.