A Case of Asymmetrical Open-Angle Glaucoma
BY LEO SEMES, OD, FAAO
We had diagnosed a 56-year-old male patient with asymmetrical open-angle glaucoma (OS worse than OD) a year earlier. The initial treatment plan included using Lumigan (0.04% bimatoprost ophthalmic solution, Allergan) qPM OU as monotherapy to achieve a target pressure of 10-to-12 mmHg in each eye. During the course of several follow-up visits over 12 months, IOP was symmetrical in each eye and ranged from 12-to-15 mmHg.
Not So Simple
The left eye demonstrated progression, based on structural assessment (optic disc and digital imaging), over the course of 12 months. Because the optic disc and visual field damage was much greater in the left eye than it was in the right eye and was progressing, we decided to attempt additional IOP reduction in the left eye only. For this we chose to add Combigan (0.2% brimonidine tartrate/0.5% timolol maleate ophthalmic solution, Allegan) qAM OS.
Additional circumstances surrounding this case are as follows:
• VA was correctable to 20/20 in each eye with mild hyperopic astigmatism.
• At baseline (07/03/07) the NFI value on GD× (Carl Zeiss Meditec, Inc.) was 23 in the right eye and 67 in the left. In addition, the GD× showed significant (p<0.2%–0.1%) retinal nerve fiber layer thinning superiorly and inferiorly in the left eye and minimal (p<0.5%) thinning isolated to the 7 o'clock-to-9 o'clock position in the right eye.
• Gonioscopy showed visibility of ciliary body over 360 degrees in each eye. There was no pigment, synechia or angle recession in either eye.
• Pachymetry was 575μm OD and 551μm OS.
• Visual field (30-2 SITA Standard) with demonstrated repeatable minimal VF depression pattern nasally OD but double arcuate depressions OS. Mean deviation was –2.34dB OD and –12.68dB OS.
• Systemic medications included a diuretic for hypertension and Nexium (Esomeprazole magnesium 40mg delayed release capsules q.d., AstraZeneca) for gastroesophageal reflux disease.
• The patient is currently in a rehabilitation program, smokes approximately one pack of cigarettes per day and uses no alcohol-containing products.
This case presents some interesting challenges. There is no history of trauma or inflammation confined to the left eye. The glaucomatous damage is distinctly asymmetrical, nonetheless. The reason for this remains obscure. The damage to the left eye revealed by the GD× NFI index (now 81) suggests progression.
In asymmetrical cases, it's a worthy objective to reduce the IOP in the more involved eye to a level lower than its fellow. We chose Combigan for this situation because its components have complementary mechanisms of IOP-lowering action (aqueous suppression and outflow enhancement) to that of the prostaglandin (specific uveoscleral outflow enhancement). In addition, there was no contraindication to using either the beta-blocker (timolol) or the alpha-agonist (brimonidine) components in this case. We expect the additional combination agent to offer an additional 2-to-4 mmHg IOP reduction.
Follow up at one week showed reduced IOP in the left eye (10 mmHg). Pressure in the right eye remained at 14 mmHg. The plan is to keep the current regimen in place and to follow the patient closely. If the IOP reduction is not sustained and visual field testing or digital imaging indicates progression, then we plan to consult with a glaucoma specialist as the left eye is now approaching maximum topical treatment. CLS
Dr. Semes is an associate professor at the University of Alabama at Birmingham School of Optometry.