Accuracy of pattern deviation in estimating the glaucomatous damage in the central 10 visual field in eyes with glaucoma and cataract

Background/aims The accuracy of pattern deviation (PD) in estimating the damage to the glaucomatous visual field (VF) in the central 10 degrees in eyes with glaucoma and cataract is unclear. Methods This retrospective study includes 63 eyes of 52 glaucoma patients who successfully underwent cataract surgery or cataract surgery plus iStent implantation. Using the Humphrey Field Analyser 10-2 test, VF was measured within 6 months preoperatively and postoperatively (VFpre and VFpost, respectively). The mean total deviation values in VFpost (mTD(post)) indicates glaucomatous damage without cataract and the difference between this value and mean PD values in VFpre (mPD(pre)) was evaluated (epsilon mPD). The effect of cataract was then evaluated as the difference between mTD(post) and mTD(pre) (Delta mTD), while the effects of mTD(post) and Delta mTD on epsilon mPD were also assessed. In addition, based on preoperative visual acuity (VA(pre)) and VFpre, the optimal model for predicting mTD(post) was identified. The error of this method (epsilon OptimalModel) was estimated as the difference against mTD(post), which was compared with epsilon mPD. Results Compared with mTD(pre), there was a significant improvement in mTD(post) (p=0.028). A significant difference was observed between mPD(pre) and mTD(post) (p<0.001). Further, epsilon mPD significantly increased with the increase of mTD(post) or Delta mTD (p<0.001 and p=0.0444, respectively). The absolute epsilon OptimalModel was significantly smaller than the absolute epsilon mPD (p<0.001). Conclusions This study warns clinicians that PD of the central 10 degrees VF might underestimate the glaucomatous VF damage with the progression of glaucoma and overestimate it as a cataract progresses.