Purpose: To assess the repeatability of individual and combined macula and optic disc volumetric analysis, and the agreement between both scan modes with optical coherence tomography (OCT) in ...glaucoma and healthy control eyes.
Methods: 27 subjects with a previous diagnosis of glaucoma were included. The control group included 34 healthy subjects older than 50 years. Volumetric measurements of the macula and optic disc were performed with a spectral domain OCT. Two different scan protocols (individual and combined) were performed in each participant, and each scan mode was repeated three times. The retinal and ganglion cell complex thickness were analysed in nine and eight sectors respectively. The peripapillary retinal nerve fibre layer (pRNFL) thickness was analysed in 12 clock sectors from the optic disc area. The repeatability limit (Rlim) and agreement analysis were performed for each sector analysis.
Results: For the retinal thickness, the differences in the Rlim between both scan modes was lower than 5 μm. The differences in the Rlim between the control and glaucoma groups were lower than 3 μm. The limits of agreement interval were lower than 20 μm for each population group. The ganglion cell complex measurements showed larger repeatability values for the combined scans for each group, and the limits of agreement intervals were lower than 13 μm. The differences in the Rlim between the control and glaucoma groups were lower than 3 μm. For the pRNFL thickness, the differences in the Rlim between both scan modes were lower than 10 μm. The control group showed lower repeatability values than the glaucoma group except on sectors 2 and 3. For both population groups, the horizontal sectors showed shorter limit of agreement intervals than the vertical sectors.
Conclusions: Similar repeatability values were obtained between both scan modes in each population group. Both scan modes cannot be used interchangeable due to the wide limits of agreement.
To study changes in the anterior chamber depth (ACD), anterior chamber angle, and pupil diameter with accommodation.
University of Valencia, Valencia, Spain.
Evaluation of diagnostic technology.
A ...rotating Scheimpflug camera (Pentacam HR) was used to measure changes in the ACD, anterior chamber angle, and pupil diameter with accommodation. Peripheral ACD was measured at the corneal center and 2.0 mm away from it in the nasal, superior, temporal, and inferior directions. The anterior chamber angle was computed as the mean anterior chamber angle of the entire eye. All measurements were obtained with accommodation stimuli ranging from +1.0 to -4.0 diopters (D) in 1.0 D steps.
Eighty subjects (80 eyes) aged 22 to 30 years were evaluated. The ACD did not vary significantly with accommodation in any location. The relative change was 3.67%, 3.65%, 3.67%, 5.66%, and 6.22% in the central, nasal, temporal, superior, and inferior locations, respectively. The central ACD values were significantly higher than the nasal, temporal, superior, and inferior values. The nasal ACD was significantly less than the central, temporal, and inferior ACD. Temporal versus inferior ACD and nasal versus superior ACD yielded similar values. No significant accommodation-related changes occurred in the anterior chamber angle or pupil diameter.
Although the ACD and anterior chamber angle remained stable with accommodation, the pupil diameter varied. Regarding location-dependent ACD variability, the nasal-superior areas were significantly shallower than the temporal-inferior areas.
No author has a financial or proprietary interest in any material or method mentioned.
To evaluate the precision of individual and combined macula and optic disc volumetric analysis, and the agreement between these two scan modes with spectral domain optical coherence tomography (OCT).
...Macular and optic disc volumetric measurements were performed with individual and combined scan protocols in one eye of 75 healthy subjects. Three repeated measurements were performed with each protocol. From the macular area, retinal thickness in nine different sectors and ganglion cell complex thickness in eight different sectors were analyzed from both scan modes. From the optic disc area, the peripapillary retinal nerve fiber layer (pRNFL) thickness in 12 clock sectors and the optic disc parameters were evaluated. For all the parameters, repeatability limit and agreement analysis were performed.
For the retinal thickness measurements in macula, the combined scan had two to three times larger repeatability limit than the individual scan for all the sectors except the central sector, where the repeatability limit was five times larger. The limits of agreement intervals were lower than 20 μm for all sectors, except the central. The ganglion cell complex measurements also had larger repeatability limits for the combined scans, and the limits of agreement intervals were <10 μm for all sectors. For the pRNFL thickness, the repeatability values were distributed like a vertically elongated ellipse for both scans, but still the repeatability was better for individual scan compared to the combined scan. The shortest and widest interval are obtained for sectors 9 (9 μm) and 12 (40 μm), respectively. The repeatability limit was <0.15 units for all disc parameters with both scan modes.
The individual macula and optic disc scans had better repeatability than the combined scan mode, and the two scan modes cannot be used interchangeability due to the wide limits of agreement.
To compare the optical quality under large apertures among three multifocal intraocular lenses (IOLs): the TECNIS Symfony ZXR00 (Abbott Laboratories, Abbott Park, IL), the AT LISA tri 839MP (Carl ...Zeiss Meditec, Jena, Germany), and the Finevision (PhysIOL, Liège, Belgium).
The in vitro optical quality of each lens was assessed with an instrument that measured the modulation transfer function (MTF). The optical quality of each lens was described in terms of MTF and through focus average MTF. The Strehl ratio, cut-off frequency, area of visibility, and percentage energy were calculated to objectively describe the optical quality of each lens. These metrics were assessed for the best lens distance focus and at four vergences (from -1.50 to -3.00 D in 0.50-D steps) at a 4.5-mm aperture.
The through focus average MTF of the AT LISA and Finevision IOLs showed three mean areas corresponding to distance, intermediate, and near vision. The TECNIS Symfony IOL showed two main areas corresponding to distance and intermediate vision. All metrics revealed that the Finevision IOL showed the best optical quality at distance vision, the TECNIS Symfony IOL at intermediate vision, and the AT LISA IOL at near vision. The TECNIS Symfony IOL showed the most homogeneous light distribution between its best vision foci.
The TECNIS Symfony IOL is less vergence dependent than the AT LISA and Finevision IOLs under dim conditions. These results may help clinicians to choose the proper lens depending on the patient's visual requirements.
Purpose
The purpose of the study was to assess non-invasively the changes in the anterior chamber eye, crystalline lens morphology, and ciliary muscle during accommodation by means of an anterior ...chamber optical coherence tomographer (OCT), and correlate them with vergence.
Methods
Twenty-five eyes of twenty-five healthy subjects, whose mean age was 29.9±7.1 years, were included and measured with an anterior chamber OCT. The central corneal thickness (CCT), anterior chamber depth (ACD), anterior crystalline lens radius of curvature (ALRC), crystalline lens thickness (CLT), and ciliary muscle area (CMA) were measured for each participant at 0, –1, –2, and –3 D of target vergence. A linear model was used to assess the correlation of each eye parameter with the vergence demand.
Results
The mean CCT showed no change for all the accommodative stimuli. The mean ACD and ALRC decreased with the vergence, about 4.5 and 30 % at –3 D, respectively. On the contrary, the CLT and CMA showed an opposite tendency, where the mean CLT was increased by 4.0 % and the mean CMA was done by 26% at –3 D. Statistical significant differences (
p
< 0.001) were obtained among all vergences for each eye metric, except for the CCT (
p
= 0.76).
Conclusion
The ACD and ALRC decreased about 2 and 10 % per dioptre of accommodation, respectively; whereas the CLT and CMA increased about 2 and 9 %, respectively. These results add knowledge regarding the understanding of accommodation and give new perspectives for biomechanics and biometry.
To analyze the effect of decentration on the optical quality of two diffractive-refractive intraocular lenses, a bifocal and a trifocal, when displaced laterally (horizontal direction) from the ...center.
The AT LISA 809M IOL (+3.75 D add) with two main foci and the AT LISA tri 839MP intraocular lens with three main foci (Carl Zeiss Meditec AG, Jena, Germany) were analyzed. The optical quality of the intraocular lenses was measured with the PMTF (power and modulation transfer function MTF measurement for refractive and diffractive intraocular lenses) optical bench (Lambda-X, Nivelles, Belgium). The optical quality of the lenses was evaluated by the MTF at different object vergences, the average modulation in the range of frequencies from 0 to 100 cycles/mm, and the through-focus MTF curves. All measures were recorded when the intraocular lenses were centered and decentered for 3.0- and 4.5-mm apertures. The Strehl ratio and the percentage of energy allocated at each focus at the centered position were also obtained.
Our results showed a lower optical quality with increasing decentration. The MTFs for the diffractive-refractive intraocular lenses decreased when the intraocular lenses were decentered. Also, the relative percentages of light energy allocated at each object vergence, for both intraocular lenses, agreed well with theoretical specifications and were consistent with the overall design of each lens.
The optical quality of these diffractive-refractive multifocal intraocular lenses was slightly reduced when the induced decentration was less than 0.4 mm. For a decentration of 0.4 mm, the maximum difference in average modulation values was about 18% compared to the centered position.
The power profile of multifocal contact lenses has been demonstrated to report important information that could be used during the fitting process. The aim of this work is to describe the power ...profile of a recent set of gas permeable multifocal contact lenses as a function of the pupil radius.
The measured multifocal contact lenses have a centre-distance design, and are available with five distance-vision diameters (XS, S, M, L and XL) and two different additions: Type A (up to +2.00 D) and Type B (up to +2.50 D). The optical device NIMO TR1504 (Lambda-X, Nivelles, Belgium) was used to obtain the power profile measurements. The optical lens power distribution as a function of the aperture radius was described in terms of radial computed colour maps, radial averaged power profiles, addition, and lens portion used for near vision.
The amount of total addition achieved depends on the diameter of the distance-vision area. That is, the bigger the distance vision area, the bigger the radius of the lens in order to get the same level of addition. In other words, the XS lens provides higher addition values compared to the XL lens design for a given aperture.
The XS and S designs seem to be aimed to favour near vision, whereas the L and XL designs seem to favour distance vision. For this reason, patients who demand good distance vision might benefit from the L or XL designs, and those with high demand on near-vision tasks might benefit from the XS or S designs. The M design could be the best option for those patients who have the same needs for distance and near vision.
This study aims to describe how in-vivo confocal microscopy (ICVM) results improved diagnosis and treatment in three patients with complex corneal disorders at a single institution. Case one was a ...36-year-old woman contact lens wearer referred to the hospital eye service (HES) by her community optician for a suspected corneal ulcer in her left eye. The case demonstrated that where laboratory cell culture was inconclusive, IVCM imaging improved diagnosis and more importantly adjusted the initial treatment till the complete resolution of the case. Case two was a shared-care 66-year-old keratoconus patient under a complex immunosuppression regime who had developed a recent series of post-surgical complications of fungal origin and was experiencing eye pain. IVCM was able to differentiate between an immune-mediated response and fungal keratitis and guide the clinicians towards an optimized treatment. Case three was a long-standing dry eye disease in a 64-year-old woman diagnosed with primary Sjögren's syndrome where previous treatments failed to improve her symptomatology. IVCM was crucial for prescribing allogeneic serum eyedrops by anticipating early immune changes in the sub-basal corneal nerve plexus. In-vivo confocal microscopy can be an essential non-invasive imaging technique for improving clinicians' diagnostic precision by adding a layer of certainty that other techniques may lack. Additionally, IVCM allows adjustment of the treatment accordingly, by instantly following any pathologic changes at the cellular level.
To determine the intrasubject repeatability of a recently introduced dual-camera rotating Scheimpflug-Placido imaging system (Galilei G4) in determining corneal thickness, power, and wavefront ...aberrations in young healthy subjects.
University of Valencia, Valencia, Spain.
Prospective evaluation of diagnostic technology.
The study comprised right eyes of 25 subjects aged 20 to 40 years with a spherical equivalent ranging from -4.25 to +1.00 diopters. The central corneal thickness, thinnest point value and location, anterior and posterior surface curvatures, total corneal power, and corneal wavefront aberrations were measured for distance vision using the dual Scheimpflug-Placido system. Three consecutive measurements were taken in each eye.
Twenty-five eyes were evaluated. Repeated-measures analysis of variance showed the only statistically significant difference between the 3 repeated measures to be in trefoil aberration. Intraclass correlation coefficients (ICCs) were higher than 0.950 for all the parameters except the thinnest point chord distance to geometric corneal center (0.528) and chord angle (0.742), corneal astigmatism (0.811) and its vector components J0 (0.891) and J45 (0.724), and all wavefront aberrations.
The new dual Scheimpflug-Placido system had high intraobserver repeatability for corneal power and thickness and moderate repeatability for corneal astigmatism and corneal wavefront aberrations in healthy corneas with low astigmatism. This iteration of the device performed better in young healthy corneas than preceding versions.
No author has a financial or proprietary interest in any material or method mentioned.
We have reviewed a set of recently published studies that compared the anterior chamber depth（ACD） and/or white-to-white（WTW） distance obtained by means of different measuring devices.Since some of ...those studies reached contradictory conclusions regarding device interchangeability,this review was carried out in attempting to clarify which clinical devices can or cannot be considered as interchangeable in clinical practice to measure ACD and/or WTW distance,among these devices：A-scan,ultrasound biomicroscopy,Orbscan and Orbscan Ⅱ（Bausch＆Lomb Surgical Inc.,San Dimas,California,USA）,Pentacam and Pentacam HR（Oculus,Wetzlar,Germany）,Galilei（Ziemer,Switzerland）,Visante optical coherence tomography（Visante OCT,Carl Zeiss Meditec Inc.,Dublin,California,USA）,lOLMaster（Carl Zeiss Meditec,Jena,Germany）,and Lenstar LS 900/Biograph（Haag-Streit AG,Koeniz,Switzerland/Alcon Laboratories Inc.,Ft Worth,Texas,USA）.
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