Ocular hypertension refers to a condition in which intraocular pressure (IOP) exceeds the statistically normal upper limit, while no detectable optic disc or visual field damage is observed, and the anterior chamber angle remains open. Clinically, this condition is referred to as ocular hypertension or suspected glaucoma. In individuals over 40 years old, approximately 7% have an IOP exceeding 21 mmHg. However, the majority of individuals with ocular hypertension do not develop optic disc or visual field damage over long-term follow-up, with only about 10% progressing to glaucoma.
The diagnosis of ocular hypertension is based solely on IOP measurements, and attention needs to be directed toward potential errors during measurement. IOP values are influenced by various factors, with central corneal thickness (CCT) being a primary source of measurement error. Optical methods typically show an average CCT of 515 μm, while ultrasound pachymetry indicates an average thickness of 541–544 μm. There is a significant correlation between CCT and applanation tonometry readings; thicker corneas are associated with higher IOP readings. For example, if the CCT exceeds normal by 70 μm, the measured IOP may overestimate the true value by 5 mmHg, whereas a thinner cornea by the same margin may lead to an underestimation of 5 mmHg. Since normal CCT varies among individuals, this variation may cause some individuals with thicker corneas to be misdiagnosed with ocular hypertension. For this reason, it is considered necessary to correct IOP values based on individual CCT measurements to obtain a more accurate assessment of true IOP.
There is currently no consensus on whether treatment should be initiated for ocular hypertension. It is generally suggested that selective treatment can be considered for individuals with risk factors, such as those with IOP exceeding 30 mmHg, a family history of glaucoma, high myopia, cardiovascular disease, or diabetes. Although most individuals with ocular hypertension do not progress to glaucoma, elevated IOP is recognized as a risk factor for the development of glaucoma. Therefore, regular follow-up is recommended for individuals with ocular hypertension, whether or not they undergo treatment.