Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT06305338 |
| Other study ID # |
KUK-Ophthalmology-009 |
| Secondary ID |
|
| Status |
Completed |
| Phase |
|
| First received |
|
| Last updated |
|
| Start date |
April 12, 2022 |
| Est. completion date |
April 26, 2023 |
Study information
| Verified date |
March 2024 |
| Source |
Johannes Kepler University of Linz |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Observational
|
Clinical Trial Summary
During cataract surgery an artificial intraocular lens (IOL) is implanted in the eye to
replace the lens and to correct the refraction for distance vision. Misalignment of IOLs can
cause severe loss of visual quality. Different types of misalignment are known. Tilt, one
type of IOL misalignment is thought to play a negative role for the optical performance in
eyes with IOL designs, especially, if they have aspheric, toric, or multifocal optics.
Various methods to measure IOL misalignments have been described. Studies assessing the IOL
position have used subjective grading methods at the slit lamp examination or a Scheimpflug
camera to assess IOL decentration and tilt. The subjective grading at the slitlamp may
display considerable variability between examiners. This method is more qualitative than
quantitative and does not allow fine resolution when reporting IOL tilt. The fact that the
patient has no standardized target to focus on makes the method even less reliable. Scanning
methods such as Scheimpflug photos require a very well dilated pupil exceeding 6mm to assess
the IOL position. Additionally, it can be difficult to identify the anatomical structures of
the eye that need to be used as points of reference. Scheimpflug camera images have been used
for assessing IOL tilt previously, but erroneous results, often due to corneal magnification,
have diminished their widespread use. Another possibility to assess tilt is the use of
Purkinje reflexes. The light reflections of Purkinje images at ocular surfaces to evaluate
ocular alignment have recently been utilized. Since light is reflected at all interfaces of
media with a difference in refractive index, these reflections, called Purkinje images, can
be used to assess tilt and decentration of IOLs. Two different clinically applicable
Purkinjemeter system provide the measurement of IOL decentration and tilt. The main problem
with Purkinje meters is accessibility, as there are only a few prototypes available
worldwide.
The most recently developed method for tilt quantification is the use of optical coherence
tomography. This method has several advantages compared to the previous methods: OCT based
devices are available in most clinics, the resolution of modern OCT devices is high, and the
measurements are reproducible.
Aim of this study is to measure tilt with two modern OCT based devices and one Scheimpflug
camera and to predict the post-operative tilt using partial least squares regression. This
method was developed by Wold and introduced to ophthalmology previously.
Description:
During cataract surgery an artificial intraocular lens (IOL) is implanted in the eye to
replace the lens and to correct the refraction for distance vision. Misalignment of IOLs can
cause severe loss of visual quality. Different types of misalignment are known. Tilt, one
type of IOL misalignment is thought to play a negative role for the optical performance in
eyes with IOL designs, especially, if they have aspheric, toric, or multifocal optics. For
example, in the case of aspheric IOLs, it appears that even slight amount of tilt may result
not only in the loss of the effect of reducing spherical aberrations but in more severe cases
even a worsening of the optical quality compared to spherical IOLs. In the case of toric
IOLs, tilt introduces higher order aberrations potentially mimicking astigmatism. In the case
of multifocal IOLs, tilt increases higher order aberrations, which leads to decreased visual
quality.
Various methods to measure IOL misalignments have been described. Studies assessing the IOL
position have used subjective grading methods at the slit lamp examination or a Scheimpflug
camera to assess IOL decentration and tilt. The subjective grading at the slitlamp may
display considerable variability between examiners. This method is more qualitative than
quantitative and does not allow fine resolution when reporting IOL tilt. The fact that the
patient has no standardized target to focus on makes the method even less reliable. Scanning
methods such as Scheimpflug photos require a very well dilated pupil exceeding 6mm to assess
the IOL position. Additionally, it can be difficult to identify the anatomical structures of
the eye that need to be used as points of reference. Scheimpflug camera images have been used
for assessing IOL tilt previously, but erroneous results, often due to corneal magnification,
have diminished their widespread use. Another possibility to assess tilt is the use of
Purkinje reflexes. The light reflections of Purkinje images at ocular surfaces to evaluate
ocular alignment have recently been utilized. Since light is reflected at all interfaces of
media with a difference in refractive index, these reflections, called Purkinje images, can
be used to assess tilt and decentration of IOLs. Two different clinically applicable
Purkinjemeter system provide the measurement of IOL decentration and tilt. The main problem
with Purkinje meters is accessibility, as there are only a few prototypes available
worldwide.
The most recently developed method for tilt quantification is the use of optical coherence
tomography. This method has several advantages compared to the previous methods: OCT based
devices are available in most clinics, the resolution of modern OCT devices is high, and the
measurements are reproducible.
Due to the fact that tilt has an influence on visual quality, the prediction of the
post-operative tilt could improve IOL power calculation significantly, especially for toric
IOLs. In the literature, the prediction of tilt was shown to be acceptable for the
orientation of tilt, but not for the amount of tilt. Furthermore, there is disagreement
concerning the fact, if the amount of tilt increases or decreases after cataract surgery.
Aim of this study is to measure tilt with two modern OCT based devices and one Scheimpflug
camera and to predict the post-operative tilt using partial least squares regression. This
method was developed by Wold and introduced to ophthalmology previously.
