Relationship between visual field progression and baseline refraction in primary open-angle glaucoma

Tomoko Naito,1 Keiji Yoshikawa,2 Shiro Mizoue,3 Mami Nanno,4 Tairo Kimura,5 Hirotaka Suzumura,6 Yuzo Umeda,7 Fumio Shiraga1 1Department of Ophthalmology, Okayama University Graduate School of Medicine, Okayama, Japan; 2Yoshikawa Eye Clinic, Tokyo, Japan; 3Department of Ophthalmology, Ehime University Graduate School of Medicine, Ehime, Japan; 4Kagurazaka Minamino Eye Clinic, 5Ueno Eye Clinic, 6Suzumura Eye Clinic, Tokyo, Japan; 7Department of Gastroenterological Surgery, Okayama University Graduate School of Medicine, Okayama, Japan Purpose: To analyze the relationship between visual field (VF) progression and baseline refraction in Japanese patients with primary open-angle glaucoma (POAG) including normal-tension glaucoma.Patients and methods: In this retrospective study, the subjects were patients with POAG who had undergone VF tests at least ten times with a Humphrey Field Analyzer (Swedish interactive thresholding algorithm standard, Central 30-2 program). VF progression was defined as a significantly negative value of mean deviation (MD) slope at the final VF test. Multivariate logistic regression models were applied to detect an association between MD slope deterioration and baseline refraction.Results: A total of 156 eyes of 156 patients were included in this analysis. Significant deterioration of MD slope was observed in 70 eyes of 70 patients (44.9%), whereas no significant deterioration was evident in 86 eyes of 86 patients (55.1%). The eyes with VF progression had significantly higher baseline refraction compared to those without apparent VF progression (-1.9±3.8 diopter [D] vs -3.5±3.4 D, P=0.0048) (mean ± standard deviation). When subject eyes were classified into four groups by the level of baseline refraction applying spherical equivalent (SE): no myopia (SE > -1D), mild myopia (-1D ≥ SE > -3D), moderate myopia (-3D ≥ SE > -6D), and severe myopia (-6D ≥ SE), the Cochran-Armitage trend analysis showed a decreasing trend in the proportion of MD slope deterioration with increasing severity of myopia (P=0.0002). The multivariate analysis revealed that baseline refraction (P=0.0108, odds ratio [OR]: 1.13, 95% confidence interval [CI]: 1.03-1.25) and intraocular pressure reduction rate (P=0.0150, OR: 0.97, 95% CI: 0.94-0.99) had a significant association with MD slope deterioration.Conclusion: In the current analysis of Japanese patients with POAG, baseline refraction was a factor significantly associated with MD slope deterioration as well as int