Retinal circulation and corneal thickness measurements and in ocular hypertensive patients and healthy controls

Abstract

Abstract: : Purpose: Patients with ocular hypertension (OHT) showed circulatory deficits of the optic nerve head in fluorescein angiography (Loebl et al, 1977). Recently, corneal thickness measurements gained importance with respect to false positive intraocular pressure measurements with increased corneal thickness (OHTS 2002). Therefore, examinations of ocular perfusion in ocular hypertensive patients might be biased due to false IOP readings. In this examination we performed measurements of retinal perfusion and central corneal thickness (CCT) in healthy subjects and patients with OHT. Methods:Twenty six patients with OHT and 26 healthy subjects were included. CCT measurements were performed on ultrasonic basis (20 MHz; Pach–pen XL, Mentor, USA). Fluorescein angiograms (SLO, Rodenstock, Germany) were analyzed with a digital analysis system. From fluorescein density profiles the arteriovenous passage time (AVP) was determined representing the perfusion through a retinal segment. Results: The CCT of the patients with OHT was significantly increased compared to healthy subjects (HS) (p=0.004, OHT: 0.571 ± 0.044 mm; HS: 0.527 ±0.038 mm). Intraocular pressure (IOP) was significantly increased in the OHT population (p<0.0001; OHT: 20 ±3 mmHg; HS: 12 ±2 mmHg). The AVP time showed no significant differences among the study populations (OHT: 1.53 ±0.56 s; HS: 1.57 ±0.39 s). The IOP was correlated with CCT (r=0.4; p=0.002). The correlation of CCT to AVP showed a tendency (p=0.1; r=–0.18), suggesting that in patients with thick corneas AVP rneasurements are even shorter. Conclusions:AVP measurements in glaucoma patients are reported to be prolonged (Arend et al 2000), whereas this study showed unaffected AVP times in OHT patients. This suggests, that in the natural course of OHT an early circulatory insult does not be a primary factor. Larger scaled examinations are required to verify the correlation of retinal circulation to CCT in OHT.

Keywords: cornea: basic science • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina