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Measurement of corneal shape and optical distortion in keratoconus and its effect on vision




Optometric Technology Group is conducting a study to measure the optical quality of the eye and of the cornea in a population with keratoconus. The purpose of the study is to quantify the optical distortions (aberrations) of the eye and the cornea and to measure their effects on vision. The aim of the project is ultimately to design contact lenses and in particularly soft contact lenses that would correct the aberrations (distortions) of the cornea created by the keratoconus and give improved vision in this group of patients traditionally only suitable for rigid contact lenses fitting. The potential benefit will be of similar vision to rigid contact lenses but improved comfort.

The participants in this study will be selected on the basis of having been diagnosed or suspected as having keratoconus in one eye or both eyes. It also includes subjects who have had a corneal graft following keratoconus. The investigation will be carried out on at least 50 subjects.

If you participate in the study, you will attend for one visit of approximately 1½ hours. There is no financial compensation for participation in this study, although you may receive compensation for travel expenses. However, you may benefit indirectly through the advancement in understanding of the corneal aberrations of the human eye and their implications for management and treatment of conditions such as keratoconus. Your vision will be evaluated during the study, however new optical corrections (spectacles or contact lenses) will not be prescribed during this time.

The study will involve the testing of vision using conventional clinical instruments. The following tests will then be undertaken with spectacle correction and contact lens correction (if applicable):

Spectacle Refraction:
Initially an automated method will be used to determine your spectacle prescription. The refraction will then be checked by the clinician using a series of spectacle lenses and your responses to the vision with these lenses.
Your vision will be measured using a standard letter chart. In addition a specific letter chart with grey letters will be used in combination with different lighting conditions. Dimmer lighting will be simulated by using goggles, which reduce the amount of light entering the eye. Your daylight vision and night vision will be evaluated.
Corneal shape:
The shape of the front of the eye (cornea) will be measured using a specialised instrument, which examines the reflection of an image on the cornea. The aberrations of the cornea will be calculated from the corneal shape.
Video Aberroscopy:
The distortions of the rays of light entering your eye will be measured and calculated using a specialised instrument.
Pupil size:
The size of the pupil will be measured using photographs. These will be taken using an infrared camera to allow the measurement in dim illumination. Ocular photographs may also be taken using conventional lighting.


The results of this study may be used for medical and scientific publications, but your identity will not be disclosed. All information, which is collected about you during the course of the research, will be kept strictly confidential. Any information about you which leaves the research clinic will have your name and address removed so that you cannot be recognised from it. It is requested that you do not disclose information concerning this investigation to anyone other than Optometric Technology Group investigators without prior permission.

This study is funded by Optometric Technology Group Limited which is an independent research facility. The plan for this study has been reviewed and approved by an independent local research Ethics Committee.


It is up to you to decide whether or not to take part. If you do decide to take part you will be given this information sheet to keep and be asked the sign a consent form. If you decide to take part you are still free to withdraw at any time and without giving a reason. A decision to withdraw at any time, or a decision not to take part, will not affect the standard of care you receive.

There is no provision for on going eye care and care by your private eye practitioner should be resumed at the conclusion of the study or if you are discontinued or withdrawn from this study.

You will be given a copy of this information sheet to keep and a copy of the signed consent form.

Marine Gobbe.
Optometric Technology Group
42 Vauxhall Bridge Road
SW1V 2RX London.
tel: 020-7932 9494

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Page last updated: 19 February, 2015