What Are The Differences Between Screenings At London Vision Clinic And At Other Laser Eye Surgery Clinics In The UK?

Mr Glenn Carp – “We like to think at the London Vision Clinic we offer pretty much the most extensive pre-screening that one can offer.  We do not rely on one or two scans to gather data from the patients.  In fact we use multiple scans of similar technology because each will have its own advantage in small specific areas.  Coupled to that a full dilated fundus examination is performed for all patients and in turn we are looking not only at the suitability from a refractive point of view but also from the medical point of view in terms of the eye.”

Differences Between Screening At Clinics Explained Further…

We perform one of the most thorough screenings for Laser Eye Surgery in the UK. The following are some factors we have deemed important to include in our screenings (many of which are rare or unique in the UK)

Discovering your uniquely personal needs – The Patient Care Coordinator is responsible for gathering the necessary information that makes you unique, in terms of your most important priorities, and your life and work style as they relate to Laser Eye Surgery.

Measuring your pupil size with certainty – We use Colvard infrared pupillometry in total darkness (with the best chance of detecting maximum natural pupil size). The best methods for determining this are either using infrared cameras or a low-level green slit light at the microscope (slit-lamp). Both have been shown to be effective methods.

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Analysing every patient’s eyes with a wavefront aberrometer – Our clinical staff analyse everyone’s eyes with the wavefront aberrometer. This differs significantly from other clinics where some patients pay more to have a wavefront analysis that will influence their treatment plan.

Imaging your corneal topography and thickness using the most up to date methods – This is one of the most important safety factors in Laser Refractive Surgery (along with front and back surface topography). We obtain two parameters to optimise the safety of surgery: The thickness at the thinnest point in the cornea and the shape of the 3D thickness profile of the cornea. Hand-held ultrasound devices used should preferably be of the 50MHz variety (many on the market are only 20-30MHz). We obtain multiple measurements of the central corneal zone, and record the thinnest measurement.

Orbscan provides a 3D thickness map of the cornea, which is essential for determining that the thickness profile of the cornea is normal, although the actual values for thickness provided are less accurate than the values we obtain by ultrasound. There is a new device now available called Artemis VHF digital ultrasound, which measures corneal thickness more accurately than either Orbscan or hand-held ultrasound devices and does so in 3D to ensure detection of the thinnest point and display the thickness profile of the cornea.

We use the Sonogage II (50MHz) hand-held probe and Orbscan II as well as Artemis VHF digital ultrasound scanning (the latter is usually used only if there is any question of suitability).

Scanning your eye with the ultrasound – During a pre-operative assessment for suitability, most laser refractive surgery practitioners will use an ultrasound probe called a pachymeter. This is a hand-held ultrasound probe that is the mainstay for accurate single point measurements of the corneal thickness. While pachymeter measurements are more accurate than those of the Orbscan are, we can only obtain them at single points, and cannot use them to adequately determine the thinnest point in the cornea. The accuracy of pachymetry is approximately 10-microns (SD). The most accurate of these devices has a +/- 5% chance of error.

The Artemis is the world’s first very high frequency (VHF) digital ultrasound eye arc-scanner. It takes advantage of the accuracy of ultrasound (and at very high-frequency) together with the 3D mapping capabilities of a scanner. In cases where there is any question regarding candidacy for surgery, we use the Artemis to be certain, and confirm safety or determine unsuitability. The accuracy of the Artemis is approximately 1-micron. It has a +/- 1% chance of error.

There is only one Artemis VHF digital ultrasound scanner in the UK (it was FDA approved in 2002), and it is available only at London Vision Clinic.

Measuring intra-ocular pressure – We measure your eye pressure using two different methods, Ocular Response Analysis and Tonometry (Goldmann). The Ocular Response Analyzer utilizes a rapid air impulse, and an advanced electro-optical system to record two applanation pressure measurements; one while the cornea is moving inward, and the other as the cornea returns. Due to its biomechanical properties, the cornea resists the dynamic air puff causing delays in the inward and outward applanation events.

Testing how you may benefit from Laser Blended Vision – If you are over 40, our optometrist will perform a Laser Blended Vision simulation in order to provide you with this option as a potential treatment plan.

Dilating your eyes to optimise treatment – Manifest, cycloplegic and analyser parameters are used to base calculations for treatment. We obtain both measurements and compare them to the wavefront aberrometer (higher order aberration) of a particular eye for optimal treatment planning.


Mr Glenn Carp explains the differences between screening at London Vision Clinic and at other Laser Eye Surgery clinics.

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I didn’t think it was possible due to my high prescription. I have worn glasses from the age of 2- wow, what a difference. I’d recommend this clinic above all others.– Anthony Avon
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What Are The Differences Between Screenings At London Vision Clinic And At Other Laser Eye Surgery Clinics In The UK? [Video]