Low-tension glaucoma can sometimes be difficult to diagnose, particularly if patients do not have a classic presentation. This case series shows the value of Humphrey visual field (HVF) 10-2 tests to identify deficits in central vision. Case 1 describes a female in her mid-60s who presented complaining of a “blind spot” in her right eye. While a HVF 24-2 suggested her test was “within normal limits,” an HVF 10-2 showed an unusually shaped scotoma in her right eye that matched her visual complaint. Case 2 describes a male in his mid-60s who was referred to the glaucoma service by a retina specialist. He complained of a “blind spot” in his left eye and was revealed to have a focal central scotoma on his HVF 10-2 test. Both patients presented with normal intraocular pressures, and both had been cleared by retina specialists and neuro-ophthalmologists. Both patients were then diagnosed with low-tension glaucoma, and treatment to date has been successful in slowing vision loss.
Low-tension glaucoma can be a difficult disease to diagnose given the relatively normal intraocular pressures (IOPs) that patients present with and the diverse visual complaints that patients have. Misdiagnoses for low-tension glaucoma range from cataracts tofloaters, all of which can easily mask the irreversible damage that low-tension glaucoma can cause. We report 2 cases with unusual presentations of low-tension glaucoma and the process of diagnosing these patients with this elusive disease.
An Asian female in her mid-60s was referred to the clinic’s glaucoma service as a low-tension glaucoma suspect due to her asymmetric optic nerves. She had a history of hypotension, perivascular claudication, and migraines. She was not on medication for these conditions. At her initial encounter, her visual acuity was 20/20 with an IOP of 14 mm Hg in both eyes. Initial refractive error was −2.75 + 2.00 × 090 in her right eye and −2.00 + 1.25 × 080 in her left eye with +2.50 add. Gonioscopy showed open angles with a wide ciliary body band and 2+ pigment in both eyes.
Her primary complaint was of a “blind spot” in the center of her right eye. Although a Humphrey visual field (HVF) 24-2 yielded nearly normal results (including a visual field index of 99%) in her right eye, an HVF 10-2 showed a prominent scotoma in the paracentral region that corresponded to the appearance of the “blind spot” (shown in Fig. 1). Marked superior retinal nerve fiber layer loss seen on the nerve optical coherence tomography (OCT) for her right eye and superotemporal loss ganglion cell loss corresponded to the inferior location of her scotoma (shown in Fig. 2a, b). The patient’s cup-to-disc ratios were 0.75 in her right eye and 0.65–0.7 in her left eye, and no disc hemorrhages were noted.
The patient was then referred to the clinic’s retina service and neuro-ophthalmology service to rule out other nonglaucomatous causes of this visual field defect. Both services cleared the patient and recommended treatment for low-tension glaucoma.
Selective laser trabeculectomy was performed in both eyes. She was prescribed latanoprost, but this was discontinued as she was intolerant to drops. One and a half years later, the scotoma in her right eye became more pronounced. Although IOP was 11 mm Hg in the right eye and 8 mm Hg in the left eye, deepening of the scotoma indicated glaucomatous progression. Selective laser trabeculectomy was then performed again in the right eye to stabilize her vision.
An African-American male in his mid-60s with a past medical history of hypercholesterolemia was referred to the clinic’s glaucoma service complaining of a “blind spot” in his left eye. He had already been cleared by the clinic’s retina and neuro-ophthalmology services and was sent to the glaucoma service to be considered for low-tension glaucoma. Both his mother and sister had glaucoma and were taking medicated drops to lower their IOP.
Upon initial exam, the patient’s visual acuities were 20/20 in his right eye and 20/100 in his left eye. IOPs measured 13 mm Hg in both eyes. His glasses prescription was plano sphere in his right eye and −0.50 + 0.50 × 108 in his left eye. Gonioscopy showed open angles with 3+ pigment and no peripheral anterior synechiae in both eyes. His cup-to-disc ratio was 0.7 in both eyes, and no disc hemorrhages were noted. Patient stated that when he looked at the Snellen vision chart, there were “letters missing” in his left eye but the rest of the chart appeared clear which reflects in his HVF 30-2 testing (Fig. 3a, b). An HVF 10-2 showed a focal central scotoma in the left eye within one degree of central vision (shown in Fig. 3c, d).
The patient’s nerve OCT showed asymmetric optic nerves with a larger cup within a small disc in the left eye and thinner neuroretinal rims (shown in Fig. 3e). There was marked ganglion cell loss, more in the left eye than in the right (shown in Fig. 3f).
The patient was treated for presumptive low-tension glaucoma and was started on brimonidine and latanoprost. His IOPs were lowered into the single digits. His visual acuity improved in his left eye to 20/20 after his IOPs were lowered, possibly due to improved ocular perfusion pressure.
Low-tension glaucoma is an elusive disease, and patients who suffer from it can be easily misdiagnosed, especially if they do not meet the classic criteria. Studies have found that women, patients with migraines, and patients with disc hemorrhages are more susceptible to low-tension glaucoma . Patients of Asian descent and patients with low systemic blood pressure are also more susceptible to having low-tension glaucoma .
The 2 cases discussed in this series are notable because both patients presented with unique complaints. Although patients with low-tension glaucoma are more likely to experience visual field deficits closer to the central axis of their vision, the patients in this case series described very specific, very focal defects in their vision. Case 1 in particular appeared to have normal HVF 24-2 test results until an HVF 10-2 showed a scotoma that corresponded with the patient’s visual complaints (shown in Fig. 1).
In both of these cases, low-tension glaucoma was almost a diagnosis of exclusion. Both patients were seen by retina specialists and neuro-ophthalmologists to rule out other etiologies of focal vision loss. OCTs, particularly ganglion cell analyses, were helpful in supporting the low-tension glaucoma diagnosis. The glaucomatous appearance of both patients’ optic nerves was also helpful in indicating the correct diagnosis. Both patients were treated to lower IOP and effectively lower risk of glaucomatous progression .
This case series should serve to demonstrate that patients with suspicion for low-tension glaucoma should be fully worked up. Patients with complaints of deficits in the center of their visual axis should have an HVF 10-2 to be evaluated for possible scotomas. If patients are then cleared by retina specialists and neuro-ophthalmologists, it may be appropriate to evaluate and possibly treat them for low-tension glaucoma. The CARE Checklist has been completed by the authors for this case report, attached as online supplementary material at www.karger.com/doi/10.1159/000529666.
Statement of Ethics
Ethical approval is not required for this study in accordance with local or national guidelines as this case series contains fewer than 3 patients. Written informed consent was obtained from participants for publication of the details of their medical case and any accompanying images.
Conflict of Interest Statement
The authors have no conflicts of interest to declare.
There was no funding of research relative to this study.
Dr. Jody He collected data and images for these cases and contributed substantially to the writing and editing of this case study. Dr. Vikas Chopra originated the idea for this case study and contributed substantially to the writing and editing of this case study.
Data Availability Statement
All data generated or analyzed during this study are included in this article. Further inquiries can be directed to the corresponding author.