Diagnostic Performance of the PalmScan VF2000 Virtual Reality Visual Field Analyzer for Identification and Classification of Glaucoma

Purpose: To evaluate the diagnostic test properties of the Palm Scan VF2000® Virtual Reality Visual Field Analyzer for diagnosis and classification of the severity of glaucoma. Methods: This study was a prospective cross-sectional analysis of 166 eyes from 97 participants. All of them were examined by the Humphrey® Field Analyzer (used as the gold standard) and the Palm Scan VF 2000® Virtual Reality Visual Field Analyzer on the same day by the same examiner. We estimated the kappa statistic (including 95% confidence interval [CI]) as a measure of agreement between these two methods. The diagnostic test properties were assessed using sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Results: The sensitivity, specificity, PPV, and NPV for the Virtual Reality Visual Field Analyzer for the classification of individuals as glaucoma/non-glaucoma was 100%. The general agreement for the classification of glaucoma between these two instruments was 0.63 (95% CI: 0.56–0.78). The agreement for mild glaucoma was 0.76 (95% CI: 0.61–0.92), for moderate glaucoma was 0.37 (0.14–0.60), and for severe glaucoma was 0.70 (95% CI: 0.55–0.85). About 28% of moderate glaucoma cases were misclassified as mild and 17% were misclassified as severe by the virtual reality visual field analyzer. Furthermore, 20% of severe cases were misclassified as moderate by this instrument. Conclusion: The instrument is 100% sensitive and specific in detection of glaucoma. However, among patients with glaucoma, there is a relatively high proportion of misclassification of severity of glaucoma. Thus, although useful for screening of glaucoma, it cannot replace the Humphrey® Field Analyzer for the clinical management in its current form

Association between anterior corneal astigmatism and posterior corneal astigmatism across age groups: a cross-sectional analysis

AIM: To assess the anterior corneal astigmatism(ACA)and posterior corneal astigmatism(PCA)patterns across various age groups. We also evaluated the association between magnitudes and axes of the ACA and PCA across these age groups. METHODS: The present study was a cross-sectional analysis of clinical data of 381 eyes. We converted the clinical astigmatic notation to vector notation for analysis of ACA and PCA. We estimated the correlation between magnitude and axes of the ACA and PCA in the whole population and in four age groups(5-19, 20-39, 40-59, and ≥ 60y). We used random effects linear regression models for estimating the association between the magnitudes of ACA and PCA.RESULTS: The mean of the magnitude of the ACA(3.59D)and the PCA(0.50D)was highest in children(5 to 9y). Overall, the magnitude of the ACA ranged from 0D to 10.0 Diopters(D)and the magnitude of the PCA ranged from 0 to 3.5 D. There was a significant correlation between the ACA and the PCA in the younger age group(r=0.85, PP=0.03)with each unit increase in the ACA, the increase was the smallest in this age group.CONCLUSION: It will be prudent to measure the both the magnitude and axis of the PCA, particularly in those above 60y rather than rely on rule-of-thumb calculations based on ACA parameters for IOL power calculation

Factors affecting changes in the intraocular pressure after phacoemulsification surgery

AIM: To assess the changes in anterior chamber parameters and examine the factors associated with changes in the intraocular pressure(IOP)in individuals who have undergone phacoemulsification surgery.METHODS: It was a longitudinal analysis of secondary clinical data collected from 105 non-glaucomatous eyes(of 82 patients)undergoing a cataract surgery. We studied the association between anterior chamber parameters, grade of cataract, demographics, and changes in the IOP over a period of 3wk. We also evaluated the association between the pressure-depth(PD)ratio and changes in the IOP during this time.RESULTS: The mean age [standard deviation(SD)] of the 82 patients was 60.1(7.8)years. The mean SD IOP was 15.06(3.36)mmHg pre-operatively; it increased to 15.75(4.21)mmHg on day one(P=0.20). In the multifactorial models, the mean IOP was -1.715 \〖95% confidence intervals(CI): -2.795, -0.636\〗 mmHg on day 21(±5)compared with the pre-operative values. The anterior chamber depth(ACD), axial length, age, sex, and grade of cataract were not significantly associated with changes in the IOP. Each unit increase in the PD ratio was associated with an increase in the mean IOP by 1.289 mmHg(95% CI: 0.906, 1.671). After adjusting for pre-operative PD ratio, none of the other variables(ACD, axial length, temporal angle)were significantly associated with changes in mean IOP.CONCLUSION: The PD ratio was the single most important factor associated with the changes in post-operative IOP over 3wk post surgery

A comparison of visual outcomes in three different types of monofocal intraocular lenses

AIM: To compare the visual outcomes (distance and near) in patients opting for three different types of monofocal intraocular lens (IOL) (Matrix Aurium, AcrySof single piece, and AcrySof IQ lens). METHODS: The present study is a cross-sectional analysis of secondary clinical data collected from 153 eyes (52 eyes in Matrix Aurium, 48 in AcrySof single piece, and 53 in AcrySof IQ group) undergoing cataract surgery (2011-2012). We compared near vision, distance vision, distance corrected near vision in these three types of lenses on day 15 (±3) post-surgery. RESULTS: About 69% of the eyes in the Matrix Aurium group had good uncorrected distance vision post-surgery; the proportion was 48% and 57% in the AcrySof single piece and AcrySof IQ group (P=0.09). The proportion of eyes with good distance corrected near vision were 38%, 33%, and 15% in the Matrix Aurium, AcrySof single piece, and AcrySof IQ groups respectively (P=0.02). Similarly, The proportion with good “both near and distance vision” were 38%, 33%, and 15% in the Matrix Aurium, AcrySof single piece, and AcrySof IQ groups respectively (P=0.02). It was only the Matrix Aurium group which had significantly better both “distance and near vision” compared with the AcrySof IQ group (odds ratio: 5.87, 95% confidence intervals: 1.68 to 20.56). CONCLUSION: Matrix Aurium monofocal lenses may be a good option for those patients who desire to have a good near as well as distance vision post-surgery