Abstract
Purpose:
To evaluate the therapeutic trend of normal tension glaucoma (NTG) patients in common Japanese clinics over a 7-year period.
Methods:
Three respective cross-sectional observational studies were conducted. A total of 3872, 4119, and 8359 eyes of 2176, 2044, and 4491 glaucoma cases who visited 33, 29, and 69 clinics/44, 50, and 97 doctors in the Kyoto and Shiga districts of Japan from January 1 to February 28, in 2006, 2009, and 2013, respectively, were enrolled. In each patient, intraocular pressure (IOP) while under therapy, severity of visual field defect (VF), glaucoma type (NTG with pre-therapeutic high teen IOP number (NTG_hi), NTG with low teen IOP number (NTG_lo), or other), patient age, and therapeutic drug usage were recorded. Of these cases, NTG cases were chosen for the further analysis. Glaucoma severity was divided into 3 stages; i.e., early, intermediate, and end-stage, based on physician evaluation of the patient’s visual field. All doctors were asked to self-declare their subspecialty and were then divided into 2 groups: 1) glaucoma specialists (G group) and 2) general ophthalmologists or specialists other than glaucoma specialists (non-G group). The therapeutic trends of NTG cases were investigated using logistic regression analysis under the parameters of study period, patient age, glaucoma type and stage, IOP, drug usage, and physician subspecialty. Statistical significance was determined as a p-value of >0.05.
Results:
The distribution of NTG among all glaucoma types increased from 27.6%, to 36.5%, to 51.4% in the 2006, 2009, and 2013 studies, respectively. Distribution of end-stage NTG also increased from 7.9%, to 9.6%, to 13.0% of all NTG cases. Mean therapeutic IOP of NTG cases decreased from 13.8±2.8, to 13.1±2.6, to 12.9±2.9 mmHg in 2006, 2009, and 2013, respectively. Logistic regression analysis showed that parameters which significantly determined end-stage NTG were study period (odds ratio: 1.156, p<0.05), patient age (1.021, p<0.001), physician subspecialty (odds ratio: 0.957, p<0.001), and the number of drugs used (odds ratio: 1.814, p<0.001), while NTG subtypes or IOP while under therapy showed no significance.
Conclusions:
During the 7-year study period, the distribution of the NTG cases, especially the end-stage NTG cases, increased gradually, even though patient IOP was more strictly controlled.