Pupil Dilation Before Fundus Exam in a Suspected Angle-Closure Patient
A 58-year-old woman presents for a routine diabetic eye exam. She mentions that 3 years ago she had a sudden painful red eye with blurred vision and halos, treated at an emergency department and now resolved. She does not recall the diagnosis. Slit-lamp shows a shallow anterior chamber in both eyes and a narrow estimated angle. Intraocular pressure is 16 mmHg in each eye today. The physician has asked you to dilate her for a fundus examination. The clinic has tropicamide 1%, phenylephrine 2.5%, and cyclopentolate 1% available.
1. Should you proceed with dilation as requested? Justify your decision using the history and findings.
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Do not dilate without checking with the physician first. The history of a painful red eye with halos and blurred vision plus a shallow chamber and narrow angle is highly suggestive of a prior angle-closure event or intermittent angle closure. Mydriatic agents (tropicamide, phenylephrine, cyclopentolate) can precipitate acute angle closure in a susceptible eye by pulling the iris root into the angle.
The safe path is to relay the history and the slit-lamp findings (shallow chamber, narrow angle) to the physician before instilling anything. The physician may defer dilation, use a shorter-acting agent with monitoring, or arrange a gonioscopy/angle assessment first. The assistant's role is to surface the risk, not to make the dilation decision unilaterally.
2. If the physician decides dilation is still necessary, what precautions and instructions would you put in place?
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Precautions: use the shortest-acting mydriatic that achieves the view (tropicamide 1% alone rather than adding phenylephrine, which also has cardiovascular considerations); instill one drop, check the angle and IOP before and after; keep the patient in the office until the effect wanes; have pilocarpine and access to the physician available.
Instructions to the patient: report immediately any eye pain, redness, halos, nausea, or decreased vision; do not rub the eye; know the clinic phone number; arrange a driver because of blur and light sensitivity. Document the consent discussion, the drops used, times, and post-dilation IOP. If the angle is judged too narrow, the physician may prefer an undilated or alternative approach.