Iris lens distance to predict the risk of intraocular pressure elevation after dark room provocative test
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To investigate if a new ultrasound biomicroscopy (UBM) parameter, iris lens distance (ILD), and its model could predict clinically significant intraocular pressure (IOP) elevation after darkroom provocative test (DRPT).
Cases with a peripheral anterior chamber depth less than one-fourth corneal thickness were enrolled. All subjects underwent UBM examination and DRPT if possible. Anterior chamber depth (ACD) and ILD were measured in the central axis at different positions in dark (ACDD, ILDD) and bright (ACDB, ILDB). An IOP elevation over 5 mmHg and 8 mmHg was set as cutoffs for a positive DRPT result (positive-5 and positive-8). SAS 9.3 statistical software was used to manage and analyze data and calculate the linear probability model (LPM). Another 17 patients (34 eyes) were included to validate the model.
Two hundred and ten (210) UBM images qualified for analysis. ILD was significantly less in the dark than in the bright and in patients with a positive DRPT result (p < 0.001). The LPM for positive-5 and positive-8 were P = 1.14 + (− 0.49*ILDD) + (− 0.41*ACDD) (n = 210, R2 = 0.1079, AUC = 0.715), and P = 0.87 + (− 0.44*ILDD) + (− 0.35*ACDD) (n = 210, R2 = 0.1358, AUC = 0.807), respectively.
LPMs based on ILD could predict the risk of an IOP elevation over 5 mmHg or 8 mmHg. The LPM for positive-8 reached a good level of diagnostic accuracy.
KeywordsIris lens distance Intraocular pressure elevation Dark room provocative test
We would like to thank the patients for taking part in this research.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the (Institutional Review Board of Peking Union Medical College Hospital) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.