Elevated IOP, thin corneas, and a family history of glaucoma
A 58-year-old woman presents for a routine eye examination. Her mother became blind from glaucoma, and she is anxious about her own risk. Goldmann applanation tonometry is 24 mmHg OD and 23 mmHg OS, with central corneal thickness of 498 µm OD and 502 µm OS. The anterior chamber angles are open to the ciliary body on gonioscopy, with no peripheral anterior synechiae. Optic discs show cup-to-disc ratios of 0.65 OD and 0.55 OS, with mild inferior rim thinning in the right eye but no disc hemorrhage. A 24-2 visual field is reliable and shows no definite defect. She uses loteprednol etabonate 0.5% twice daily for allergic conjunctivitis, started 2 months ago. She is otherwise healthy, takes no systemic medications, and has no known diabetes or hypertension. She asks whether she has glaucoma and whether she needs drops.
1. How do you interpret the IOP in light of the corneal thickness and steroid use?
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A Goldmann reading of 23–24 mmHg is above the usual statistical range, but corneal thickness affects applanation. Thin central corneas tend to produce an artificially low Goldmann reading, so her true IOP may be somewhat higher than measured. I would not apply a single correction factor as if it were exact; nomograms vary and do not replace clinical judgment. Thin CCT is also an independent risk factor for glaucoma. The loteprednol is important: topical steroids, even “soft” ones, can raise IOP in steroid responders, and she has been using it twice daily for 2 months. I would ask who prescribed it and whether it can be stopped. I would repeat tonometry at different times of day, confirm the reading with a second technique if needed, and interpret the numbers alongside the disc appearance, family history, and visual field rather than in isolation.
2. What additional testing and follow-up would you arrange?
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I would obtain baseline optic nerve photographs and OCT retinal nerve fiber layer thickness, recognizing that the right disc already shows mild inferior thinning. I would repeat the 24-2 visual field and consider a 10-2 field if the disc appearance suggests early paracentral loss. I would perform gonioscopy again and document the angle anatomy. I would coordinate with the prescribing clinician to stop loteprednol if possible and recheck IOP in 4–6 weeks; if IOP remains elevated after stopping the steroid, that strengthens the case for intrinsic ocular hypertension or early glaucoma. I would also check blood pressure, review medications and symptoms of sleep apnea, and ask about any vasospastic disease. Follow-up should be closer than routine-perhaps 3–4 months initially-so that progression can be detected. I would explain that one normal field does not exclude glaucoma.
3. Would you start treatment now or monitor? Explain your reasoning.
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She does not meet a simple “treat everyone above 21” rule, and she does not yet have a definite visual field defect. However, she has several risk factors: thin corneas, a family history of severe glaucoma, borderline-to-elevated IOP, and mild inferior rim thinning in the right eye. The steroid use is a modifiable confounder. My first step would be to stop the loteprednol if medically appropriate and reassess IOP, because treating a steroid response with lifelong glaucoma drops without removing the cause would be poor judgment. If IOP remains elevated off steroids, or if OCT or fields show progression, I would initiate treatment or refer to a glaucoma specialist. If everything is stable after steroid cessation, close monitoring is reasonable. I would document the risk discussion and make sure she understands that “glaucoma suspect” means watching, not ignoring.