Abstract
Purpose: :
Corneal collagen cross-linking (CXL) using riboflavin (vitamin B2) and UVA irradiation has recently been introduced as a novel therapeutic option for the treatment of corneal ectasia, such as keratoconus. An increase in overall stiffness and rigidity in human corneas of up to 330% has been reported following this treatment to investigate whether CXL affects the Tonopen measurments of intraocular pressure. (IOP)
Methods: :
CXL with 0.1% riboflavin solution and 30 minutes of UVA radiation was performed on the right eye of 15 New Zealand albino adult rabbits (1.8 to 2.4 kg) (30 eyes). The left eye served as a control. IOP was measured by a pressure transducer system (True IOP) and by the Tonopen hand held device (corneal applanation tonometer) before treatment, at 1 week, 1 months and 3 months following CXL. Reference pressure in the globe was increased by increments of 10 mm Hg from 10 to 40 mm Hg, using an anterior chamber infusion on a stand with variable height, and tonopen IOP measurments were recorded for each reference pressure, in both eyes.
Results: :
Before CXL, tonopen readings were similar between the two eyes.Tonopen underestimated the true IOP in all cases. Following CXL treatment, IOP measurments were significantly higher in treated eye, at all time interval. (0.009<P<0.03) The most significant difference between true and measured IOP was noticed at 20 mmHg.
Conclusions: :
IOP measurments following CXL are overestimated by the Tonopen, probably due to increased stiffness of the treated cornea.
Keywords: cornea: basic science • cornea: clinical science • intraocular pressure