Abstract:  Objective To observe the short-term intraocular pressure (IOP) fluctuation curve and its regularity in Chinese patients with pigment dispersion syndrome (PDS) after mydriasis. Design Prospective cases series. Participants Twenty-one eyes of 21 Chinese patients with PDS presenting for care at the glaucoma specialty clinic in Beijing Tongren Hospital, from August 2021 to January 2022, including 10 eyes with simple PDS and 11 eyes with PDS complicated with pigment glaucoma (PG). Methods Medical history, essential ophthalmological examination, and initial IOP was collected. One eye of each patient was randomly selected as the research object, in which compound tropicamide eye drops were instilled twice with an interval of 15 minutes. The IOP was measured 5 minutes after the second instillation and repeated hourly for eight consecutive measurements until the pupil diameter recovered to the level at enrollment. Main Outcome Measures IOP values pro- and post-mydriasis, IOP fluctuation curve. Results The initial IOP of these PDS eyes (n=21) was (18.0±3.1) mmHg, which rose to the highest level of (19.4±4.2) mmHg at the second post-mydriasis hour, with a mean increase of (1.4±2.6) mmHg (t=-2.425, P=0.025). The magnitude of IOP fluctuation was (5.4±2.8) mmHg among all enrolled eyes after pupil dilation. The initial IOP of those simple PDS eyes was (18.0±3.2) mmHg, and the average IOP of PG eyes was (18.0±3.1) mmHg. They reached the highest IOP level at the third and fourth hour after the mydriasis, at (19.4±5.2) mmHg and (19.8±5.6) mmHg, with an increase of (1.4±3.3) mmHg and (1.7±4.3) mmHg, respectively. Thirteen PDS eyes with laser peripheral iridotomy (LPI) before admission had an average IOP of (18.6±2.6) mmHg, and the remaining 8 PDS eyes without LPI had an initial IOP of (17.1±3.8) mmHg, which peaked at the third and fourth post-mydriasis hour at (19.7±4.1) mmHg and (19.2±7.3) mmHg respectively, with an increase of (1.2±2.6) mmHg and (2.0±5.1) mmHg. On admission, three (14.3%) of these enrolled PDS eyes had initial IOP of above 21 mmHg. After pupil dilation, ten of the enrolled eyes (47.6%) had at least one measurement of over 21 mmHg. IOP fluctuation of 8 mmHg or more was discerned in 3 of these PDS eyes, all of which were PG eyes, and the highest IOP was 32 mmHg. Conclusion Mydriasis has a mild effect on IOP fluctuation in Chinese patients with PDS. Pupil dilation is unlikely to causes intensive IOP spike in these patients. (Ophthalmol CHN, 2024, 33: 87-92)

Key words: pigment dispersion syndrome, pigmentary glaucoma, mydriasis, intraocular pressure