Clinical Trial Details
— Status: Not yet recruiting
Administrative data
| NCT number |
NCT04816266 |
| Other study ID # |
Anterior chamber depth |
| Secondary ID |
|
| Status |
Not yet recruiting |
| Phase |
|
| First received |
|
| Last updated |
|
| Start date |
April 1, 2021 |
| Est. completion date |
April 1, 2023 |
Study information
| Verified date |
March 2021 |
| Source |
Assiut University |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Observational
|
Clinical Trial Summary
Measuring parameters of anterior segment of the eye accurately is important for diagnosing
variety of diseases and for cataract surgeries, glaucoma, refractive surgeries and
post-operative follow-up. One of the anterior segment parameters is the anterior chamber
depth.
The anterior chamber depth (ACD) measurement provides valuable information in different
fields in ophthalmology. Firstly, it is important for the new theoretical biometric formulas
used to calculate the power of intraocular lenses (IOLs) .Secondly, phakic IOL implantation
requires precise ACD measurement for both surgical planning and IOL power calculation.
Thirdly, the ACD is also implicated as a screening risk factor for glaucoma. Additionally,
precise ACD measurement is thought to be important to the accurate determination of the optic
zone ablation diameter for keratorefractive surgery, as well as for the analysis of
postoperative ACD changes.
Different technologies are used in measurement of the anterior chamber depth Such as pentacam
and iol maste
Description:
IOL master :
Optical biometry by the IOL Master was introduced in the United Kingdom in 1999.Its
technology is based on laser interfer-ometry with partial coherent light, termed as Partial
Coherence Interferometry (PCI).The device uses the principle of PCI to measure the axial
length of the eye.While uses a slit-beam photo-graphic technique for ACD measurements For
keratometry measurement, six light spots are projected hexagonally on the cornea .The device
records the reflection of these images measuring the separation of the opposite pairs of
light spots and calculating the corneal radii and toroidal surface curvature. The mean of the
taken measurements is considered the corneal power . The displayed K1 and K2 represent the
average keratometry values at two major perpendicular meridians .For ACD measurement, the IOL
Master directs a slit beam of light 0.7mm wide through the anterior segment at an angle of
38ยบ to the visual axis.The internal software measures the distance between anterior pole of
the cornea and the anterior surface of the lens to calculate the ACD . The device takes five
ACD measurements in rapid succession; the mean of these readings are taken as the ACD value .
For WTW measurement, a digital grey-scale photograph of the anterior surface of the eye is
taken after focusing on the iris. The limbus is then detected automatically and the WTW
distance is measured
Pentacam :
The Pentacam obtains images of the anterior segment by a rotating Scheimpflug blue Light
Emitting Diode (LED) with a wavelength of 475nm. It acquires 50 images in a duration of
approximately two seconds. It extracts about 2,760 true elevation points from the obtained
images which in turn generates 1 38,000 true elevation points for the both front and back
corneal surfacesand from limbus to limbus, including the central part of the cornea . There
for, it calculates k-readings of the cornea. The Pentacam HR calculates ACD from the corneal
endothelial layer along a line from the apex of the cornea to the anterior surface of the
lens . Horizontal WTW was measured by manual placement of callipers on the Scheimpflug image
of the horizontal plane of the examined eye; callipers are placed on the corneo-scleral
junction then a line is automat-ically drawn between the two points . The length of this line
represents the WTW value
