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The probability of having glaucoma at different IOP levels
Author(s) -
Davanger Martin,
Ringvold Amund,
Blika Sigmund
Publication year - 1991
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.1991.tb04840.x
Subject(s) - glaucoma , ophthalmology , normal tension glaucoma , mathematics , medicine , probability distribution , population , intraocular pressure , normal distribution , distribution (mathematics) , statistics , open angle glaucoma , mathematical analysis , environmental health
Abstract The probability of having glaucoma is indicated by the quotient (number of eyes with glaucoma)/(number of eyes in the total population). This quotient was calculated for each value of IOP. The number of eyes at each IOP value was taken from IOP frequency distribution curves for glaucomatous and normal eyes, calculated from values obtained by a population survey. By plotting the probability of having glaucoma vs IOP, a sigmoid curve was obtained. The curve indicates that while the glaucoma probability is near zero at IOP = 18 mmHg, it is 0.5 at 27–28 mmHg, and the probability approaches 1, i.e. certainty, at an IOP around 35 mmHg. The frequency distribution of the tolerance limit of IOP was calculated by derivation of this curve. The distribution of IOP tolerance limit was close to a normal distribution with average = 27.9 mmHg and standard deviation = 3.2 mmHg.