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KENJI OZAWA, Akira Sawada, Tetsuya Yamamoto; Legal blindness in normal tension glaucoma: a subgroup analysis. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1977.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the probability of going blindness between low and high maximum intraocular pressure (IOP) groups in eyes with normal tension glaucoma (NTG).
We retrospectively investigated 380 patients diagnosed as bilateral NTG between 1985 and 2007, and followed for at least 5 years. We reviewed the patients’ data of best-corrected visual acuity and visual field from our records. A cut-off value of maximum IOP was tentatively set as 18 mmHg. The blindness was defined according to the World Health Organization (WHO) criteria. The probabilities of blindness were calculated using Kaplan Meier life-table analyses.
The mean age at diagnosis was 55.8 ± 11.8 years. Men were 158, and women were 222. The mean follow-up period was 14.0 ± 5.7 years. The low IOP group included 205 patients (53.9%). Nineteen patients (5.0%) had already had unilateral blindness due to glaucoma at diagnosis. Twenty-two cases (12.6%) in the high IOP group and 16 cases (7.8%) in the low IOP group finally had blindness in at least one eye at the last visit (P=0.123; Chi-square test). In the high IOP group, the probability of blindness in at least one eye was estimated to be 9.3 ± 2.0% at 10 years, 14.4 ± 3.2% at 20 years and 22.8 ± 6.5% at 25 years. On the other hand, in the low IOP group it was estimated to be 3.8 ± 1.4% at 10 years, 11.2 ± 3.1% at 20 years and 17.9 ± 5.4% at 25 years. There was no significant difference in probability of blindness in at least one eye between the two groups (P=0.090; log-rank test).
In the present study, we failed to detect the difference in probability of blindness between high and low maximum IOP groups in NTG patients.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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