Spectral analysis of the IOP pulse appears to be a promising technique in the investigation of ocular vascular disease.

Background/aim-It is widely accepted that hypercapnia results in increased retinal, choroidal, and retrobulbar blood flow. Reports of a visual response to hypercapnia appear mixed, with normal subjects exhibiting reduced temporal contrast sensitivity in some studies, while glaucoma patients demonstrate mid-peripheral visual field improvements in others. This suggests that under hypercapnic conditions a balance exists between the beneficial eVects of improved ocular blood flow and some other factor such as induced metabolic stress; the outcome may be influenced by the disease process. The aim of this study was to evaluate the contrast sensitivity response of untreated glaucoma patients and normal subjects during mild hypercapnia. Methods-10 previously untreated glaucoma patients and 10 control subjects were evaluated for contrast sensitivity and intraocular pressure while breathing room air and then again during mild hypercapnia. Results-During room air breathing, compared with normal subjects, glaucoma patients had higher IOP (p = 0.0003) and lower contrast sensitivity at 3 cycles/ degree (cpd) (p = 0.001). Mild hypercapnia caused a significant fall in contrast sensitivity at 6, 12, and 18 cpd (p < 0.05), only in the glaucoma group. Conclusion-Glaucoma patients with early disease exhibit central vision deficits as shown by contrast sensitivity testing at 3 cpd. Hypercapnia induces further contrast loss through a range of spatial frequencies (6-18 cpd) which may be predictive of further neuronal damage due to glaucoma. (Br J Ophthalmol 2001;85:1352-1356

Purpose To investigate intraocular pressure (IOP) and ocular haemodynamics following small incision cataract surgery. Methods Systemic and ocular haemodynamics, and IOP, were measured pre-operatively and 1 month post-operatively, in 25 eyes of 25 patients (mean age 72.677.9 years) scheduled for small incision cataract surgery and intraocular lens implantation; these values were compared to an untreated age-matched healthy group (n ¼ 25, mean age 72.375

Photodiode sensitivity as indicated by the DC value affects measurements of ocular blood flow using the HRF.

No abstract

Background/aim-Blood flow measures acquired using the scanning laser Doppler flowmeter (SLDF) are known to be highly susceptible to spatial and temporal variations of physiological origin. The purpose of this study was to evaluate a local search strategy intended to overcome these intrinsic variations, thereby improving the detection of blood flow defects resulting from glaucoma. Methods-The sample consisted of one eye of each of 15 glaucoma patients (aged 69.1 (SD 6.6) years) and 15 normal subjects (aged 65.2 (13.7) years). Three 10 degree images of the superior temporal retina and three images of the superior temporal rim were acquired using the Heidelberg retina flowmeter (HRF). Standard analysis was performed using a 10 × 10 pixel frame. For the search strategy the same frame was located within a 15 × 15 pixel window and manually repositioned in order to identify the highest and lowest local values of blood flow. Student's paired t test was used to identify diVerences between groups for the two methods (p<0.05). The scanning laser Doppler flowmeter (SLDF) measures blood flow, volume, and velocity in the retina and neuroretinal rim. It combines the optical Doppler eVect with scanning laser flowmetry to give values of capillary blood flow, volume, and velocity measured in arbitrary units. Infrared light with a wavelength of 780 nm is emitted from the instrument and reflected from both stationary and moving objects. Interference occurs between light reflected from the relatively stationary background, such as the blood vessel walls, and that reflected from moving objects, such as the red blood cells. This interference results in a beat frequency, which is proportional to blood corpuscle velocity. Results-The

Capillary blood flow in the retina, neuroretinal rim and lamina cribrosa decreases with advancing age. This may be of consequence in the progression of chronic ocular diseases such as glaucoma, and should be considered in the longitudinal determination of change in disease monitoring.

Ten-degree SWAP is able to effectively detect focal visual field loss in central retinal eye disease which may precede those found using conventional perimetry. SWAP may prove to be an invaluable technique for the investigation of central retinal eye disease.