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.

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