QuickSee Free: Frequently Asked Questions

QuickSee Free is an open-view autorefractor. The open-view optical system allows the patient to look through the device at a distant target, which helps reduce their accommodation and ensure more accurate measurements.

It is highly recommended  that the visual target be illuminated or brightly colored, so that the patient can easily focus on it instead of the internal red dot (the red dot is illumination for the wavefront aberrometry measurement). It is highly recommended to avoid the distant visual target being a white wall or a large monochromatic object. The best distant visual targets are textured, brightly colored, multicolored, and/or illuminated and draw the attention of the patient.

During the measurement, it is highly recommended to ask the patient to describe the distant visual target so that you can ensure they are not accommodating (accommodation would over minus the autorefraction results). Avoid asking simple “yes / no” questions such as “do you see the distant visual target?”, as the patient may say “yes” while actually looking at the internal red dot. It is best to ask questions that you can verify such as “what color is the distant visual target?” or “how many books are there on the bookshelf?”

If the patient is myopic, then they may not be able to view a distant target, in which case it is  likely they will accommodate on the internal red dot, which would result in an over minused autorefraction results. For such patients, ask them to describe what colors they see when looking at the distant visual target.

Use of the fogging lenses is optional and at the discretion of the operator (or health professional). The fogging lenses can be added to ensure the patient is fogged (to reduce their accommodation) during the measurement. This may be particularly useful for children (who have strong accommodation) and hyperopes (for whom the open-view system may not fully relax their accommodation). 

Please refer to the following scientific paper, Principles and Technique of Fogging During Subjective Refraction; Mutali J. Musa; Marco Zeppieri.

Some clinicians and researchers have advised to use the standard 2D fogging lens to relax the patient’s accommodation to obtain a result similar to that achieved by cycloplegia* and use the 4D fogging lens to check if additional tonic accommodation (in high hyperopes and children) is present.

Fogging is a standard feature in closed-view desktop autorefractors, and is used because desktop autorefractors tend to over-minus the patient’s autorefraction results (due to instrument-induced myopia).

Fogging of a patient can also be achieved through the use of cycloplegia, however, it is associated with patient discomfort, additional cost and time, and risk of increased intraocular pressure or other potential side effects. 

In most countries in Europe, optometrists are forbidden from using cycloplegic agents, as they can only be administered by an ophthalmologist.

*citation: Keiros et al, Effect of fogging lenses and Cycloplegia on open-field automatic refraction , “Ophthalmic and Physiol Optics”. 2008,28(4):387-92

It is highly recommended to use the occluder while performing a QuickSee Free measurement in order to ensure that ambient light does not cause both pupils (including the measured eye) to constrict. The passive dilation effect will also help ensure the pupils are large. 

Ensure that the patient keeps both eyes open (including the occluded eye) during the measurement to avoid a squint reflex which will partially cover the measured eye and make alignment and measurements more difficult.

Without the occluder, the patient’s pupils may constrict due to ambient light, making measurement more difficult.

The eyecup does not need to be used all the time although we highly recommend its use for every measurement so that stray light does not cause the measured eye’s pupil to constrict (which would make the measurement alignment more difficult). 

If multiple people operate the device and do not standardize on the use of the eyecup and occluder, there is potential that they will obtain different autorefraction measurements for the same patient because the patient may squint due to stray light.

It is important that the operator instruct the patient to blink 2-3 times during the 10 second measurement. Ideally, the patient will blink at the beginning, middle, and end of the 10 second measurement. 

Blinking helps the patient relax, reduce their accommodation, and refresh their tear film. The tear film is an important contributor to the eye’s refractive power.

Yes, both devices, QuickSee and QuickSee Free, can be used with dilated pupils. QuickSee was evaluated in a clinical study on children with and without cycloplegia, which also dilates the pupils. In fact, the bigger the pupil the better the measurements, since more data is collected from the eye. This is why we occlude  the contralateral eye but require it to remain open during measurements with QuickSee Free. When dilated, the operator may want to pay attention to ensuring the device is aligned to the center of the pupil.

The measurements can be taken with pupils in the range of 2-8 mm, but can also likely be used on pupils as small as 1.5 mm with a smaller measurement range. QuickSee Free uses a pupil camera to make the alignment process much easier. Our algorithms ensure that we collect sufficient quality data before providing an autorefraction result. If an autorefraction result is given by the device, then it means our algorithms have determined that the pupil size was big enough and enough wavefront data was collected from the eye to provide an accurate result. If the pupil size is too small, we recommend that you take the measurement using the eyecup and/or in a darkened environment, and also to use the occluder to also assist in creating passive dilation (see occluder FAQ).

If the cataract is small, QuickSee Free should be able to measure the refractive errors accurately. The presence of mature cataracts may affect the results, so the refractive error estimate is contraindicated in this case. If the cataract blocks too much of the signal (see the spot diagram as this will show the effect of opacity) then it is likely QuickSee Free will not be able to measure the refractive errors.

For instance, if <50% of the spots are blocked, then it is likely QuickSee Free will be able to take a measurement. We have not completed a clinical study specifically measuring patients with various grades of cataract (mild to advanced), so we cannot provide information about QuickSee Free measurement performance for different grades of cataracts. A trained professional can view the spot diagram and may be able to determine if an opacity is present and that the patient should undergo further evaluation. The device will not output any message or diagnosis regarding this. It is the responsibility of the user of the device to determine if further evaluation is required.

QuickSee Free and QuickSee Free Pro use sophisticated algorithms to perform the wavefront aberrometry and keratometry measurements, and are set to a certain vertex distance (12 mm). It is recommended that measurements be performed when the device is properly aligned and at the proper vertex distance. Typically, you are at the proper vertex distance when the device is properly positioned on the patient’s face so that the eyecup is depressed and the two posts of the device are touching the patient’s face.

QuickSee Free and QuickSee Free Pro provide objective measurements (without the patient’s feedback) of the refractive power of their eyes. The objective measurements can be affected by factors including poor positioning and alignment of the device, incorrect vertex distance, patient accommodating because he/she is not looking at the distant target, etc.

Subjective refraction, the clinical gold standard for eyeglass and contact lens prescriptions, is a process carried out by an eye care professional wherein different combinations of lenses are placed in front of the patient’s eyes in order to improve visual acuity while taking into account the patient’s preference for the different combinations of lenses. For instance, a certain combination of lenses may optimize the patient’s visual acuity, but may cause strain on their eyes or make them feel uncomfortable,which is related to how their visual cortex in their brain processes visual information. During subjective refraction, the eye care professional may take into account the difference in refractive power between the two eyes to modify the prescription (balancing), or may take into account the patient’s eyeglass (or contact lens) prescription history to under or over-correct a refractive error—e.g., astigmatism correction is often under-corrected for patients’ who have never had vision correction.

Objective and subjective refraction are performed differently and take into account different parameters.

Published, peer-reviewed, scientific and clinical articles demonstrating QuickSee and QuickSee Free’s strong agreement with subjective refraction are available in the Publications section of our website. It is not expected that QuickSee Free or QuickSee Free Pro will match the subjective refraction of all patients due to the examples mentioned above.

To obtain measurements in children we recommend the following:

• Measurements may be performed on children that are at least 3 years old. They need to be able to follow instructions and keep their focus on the distant target (and to not look at the red dot) during the measurement.
• We recommend using a colorful, bright and/or illuminated visual target (for example, something that is engaging or maybe has animals or hidden figures in it) for the child to look at through the device.
• During the measurement ask the child to describe the visual target (or to count the animals, or find the hidden figures, etc.) during the measurement, which will help them keep their focus on the fixed distant point and will thus reduce accommodation.
• At the preference of the operator, the fogging lenses can be used on hyperopic children, such as latent hyperopes (see section on Fogging Lenses).
• We also recommend that the operator use his/her free hand to hold the child’s head steady as children may tend to move more than adults during the measurement.

QuickSee Free can be used during mydriasis (pupil dilation). When the pupil is fully dilated, it is important to ensure that the device is aligned to the center of the patient’s pupil.

To avoid using mydriasis, also see the section on the Occluder and Eyecup.

Please refer to the scientific paper, Principles and Technique of Fogging During Subjective Refraction; Mutali J. Musa; Marco Zeppieri.