To investigate the relationship between glaucoma severity and intraocular pressure (IOP) reduction after cataract surgery in patients with medically controlled primary open-angle glaucoma (POAG). Retrospective case series. This study included glaucoma suspects (GS) and POAG patients who underwent cataract surgery and continued to use the same glaucoma medications during the postoperative period of 4 months. The main outcomes were percent and absolute IOP changes calculated using the preoperative IOP and the postoperative IOP at 3 months. Preoperative glaucoma medications, preoperative IOP, demographic information, biometric parameters and variables for glaucoma severity were evaluated as potential predictors of IOP change. The average IOP reduction was 3.3 ± 2.4 mmHg (20.0%) and 2.2 ± 2.5 mmHg (13.1%) from the preoperative mean of 16.0 ± 2.9 mmHg and 15.2 ± 3.3 mmHg in the GS and POAG groups, respectively. Preoperative IOP, preoperative IOP/anterior chamber depth (preoperative IOP/ACD [PD ratio]) and preoperative IOP/retinal nerve fiber layer (RNFL) thickness (preoperative IOP/RNFL [PNFL ratio]) and preoperative IOP score x MD score x number of glaucoma medications (glaucoma index) predicted absolute IOP change in the POAG group, whereas preoperative IOP, PD ratio, PNFL ratio, and axial length (AL) did in the GS group. Preoperative IOP, PD ratio, and PNFL ratio predicted %IOP change in the POAG group, whereas only AL did in the GS group. In medically controlled POAG eyes, structural or functional parameters for glaucoma severity did not independently predict IOP change following phacoemulsification. However, novel severity indices obtained by addition of preoperative IOP and/or glaucoma medications to the structural or functional parameter predicted IOP changes.
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Unlike MD, VFI or PSD, the PNFL ratio was found to predict absolute and percent IOP change after phacoemulsification in this study. Given the fact that the POAG group of this study sample included predominantly early to moderate POAG, RNFL thickness may better serve as an indicator of glaucoma severity at this zone of the disease spectrum. Our finding of PNFL ratio as a positive predictor of IOP change after cataract surgery suggests that greater IOP reduction may be obtained in eyes with higher preoperative IOP and/or thinner RNFL, which reflects relatively greater resistance to medical treatment or greater structural damage, such as to the outflow tract. This assumption is supported by a positive association between a higher GI and IOP reduction after phacoemulsification. However, this issue warrants further studies with larger sample sizes including more severe glaucomatous damage.
Copyright © 2018 the Author(s).
- Cataract surgery
- Intraocular pressure
ASJC Scopus subject areas