Frequency Doubling Technology Perimetry and Central Corneal Thickness in people with high intraocular pressures and normal discs

Abstract

Aim: To study the correlation between central corneal thickness (CCT) measured by ultrasound pachymetry and Frequency Doubling Technology Perimetry (FDT) in patients aged more than or equal to 40 years with high IOP and normal discs. Materials and Methods: This research work has two arms, the rural arm is an eye care centre in Hooghly District of West Bengal (Village: Kuliapara, P.O. Dhobapara, P.S. Balagarh)and the urban arm is a tertiary eye hospital in Kolkata, West Bengal. People aged 40 years and above or those turning 40 in the calendar year with high IOP and normal discs and not on any topical or systemic medications underwent complete ophthalmological examination including CCT assessment by ultrasound pachymetry (Ocuscan RxP) and FDT (Humphrey, Carl Zeiss) . Patients with history of intraocular surgery, ocular trauma, corneal opacities preventing accurate applanation tonometry and media haze dense enough to preclude adequate fundal view were not enumerated. Results: One hundred and eighty subjects fulfilled the laid down study inclusion criteria. Average CCT for the right eye(RE) is 530.74 µ and that for the left eye(LE) is 531.32µ(p=0.61, not statistically significant). IOP in the RE varied from 18 to 32 mm Hg with an average value of 23 mm Hg and that in the LE varied from 14 to 32 mm Hg with an average value of 22 mm Hg. Abnormal FDT in either eye was present in eighteen subjects of whom nine subjects had bilateral abnormal FDT and eight subjects had only RE affection and one subject had only LE affection. Conclusion: Our study concludes that the included subjects with abnormal FDT had thinner CCTs as compared to those with a normal FDT. Extending this relation further, we conclude that among subjects with a higher IOP and normal discs or patients grouped as ocular hypertensives, thicker corneas lower the risk for development of early glaucomatous functional damage as picked up by FDT, as compared to patients with thinner corneas.