Straylight measurements in pseudophakic patients

Especially in older patients cataract is a common cause of intraocular
opacities causing a decrease in visual functioning. The outcomes of a cataract
extraction can be hard to predict for individual patients, as unknown factors
play a role. The effect of straylight caused by the cataractous lens and the
implanted lens is possibly one of these factors.
Straylight is caused by a reduction in contrast of the retinal image due to a
veiling luminance caused by forward light scatter within the eye. This causes
halo's around bright light sources and difficulty with against the light object
recognition. These complaints can be very distressing and invalidating to the
patient, while standard examinations are relatively normal. Until now, loss of
function was qualified only by visual acuity measurements. However, straylight
measurements may offer a significant contribution. Patients with many
subjective complaints may still have a good visual acuity. Their complaints may
be explained by an increased straylight value.
Also in pseudophakic patients straylight plays a role. The subjective
complaints of straylight in these patients seem to show significant variation.
The measured amount of straylight can also vary very much among pseudophakic
patients. It is still unknown which contribution to these complaints is made by
the intraocular structures (e.g. pupil size, anterior and posterior lens
capsule, capsulorhexis and IOL edge).
A new version of the straylightmeter, the Oculus C-Quant, is available since
June 2005. This straylight meter is able to objectively measure the amount of
straylight and to express this as a number. In the present study we are
planning to use the Oculus C-Quant to measure the amount of straylight in
pseudophakic patients. We are planning to relate the amount of straylight to
subjective complaints and intraocular factors (e.g. the presence of corneal and
capsular opacities and the size of the capsulorhexis).

To determine straylight values in pseudophakic patients. This study will lead
to objective documentation of loss of visual function among pseudophakic
patients and will lead to more insight in the etiology of straylight among this
group of patients. In this way we can contribute to better preoperative
information to patients with cataract who are considering a cataract
extraction. It will also be possible to better treat intraocular straylight
causing factors in pseudophakic patients with complaints of visual functioning,
especially straylight complaints.

This study is an observational cohort study.
The examination of the pseudophakic patients will consist of:
- notation of their subjective complaints of straylight
- best corrected visual acuity measurement
- measurement of straylight and (undilated) pupil size
- standard slitlampexamination
- cornea pachymetry
- corneal endothelial cell counts
- photographic documentation of the anterior segment of the eye and the
intraocular lens

The patient will make one study visit to the Department of Ophthalmology,
lasting between 1,5 and 2 hours. The measurements will pose no extra risk for
the patients.