暂无摘要。

BACKGROUND: Quantitative analysis of retinal nerve fibers is important for the diagnosis and treatment of optic nerve diseases. Peripapillary retinal nerve fiber layer (RNFL) cross-sectional area may give a more accurate quantitative assessment of retinal nerve fibers than RNFL thickness but there have been no previous reports of the peripapillary RNFL cross-sectional area or other parameters. The purpose of the current study was to determine peripapillary RNFL cross-sectional area and its association with other factors in an adult Chinese population.
METHODS: RNFL cross-sectional area was measured during peripapillary circular optical coherence tomography (OCT) scan with a diameter of 12° centered on the optic disc. Correlation between RNFL cross-sectional area and other parameters was evaluated by linear regression analysis in a cross-sectional study of an adult Chinese population.
RESULTS: A total of 2404 eyes from 2404 subjects were examined. Multivariate linear regression analysis showed that larger RNFL cross-sectional area correlated with younger age (p < 0.001), female gender (p = 0.001), no history of diabetes (p = 0.012) and larger optic disc area (p < 0.001).
CONCLUSIONS: Peripapillary RNFL cross-sectional area is correlated positively with optic disc area, suggesting that eyes with larger optic discs have thicker RNFL. Further studies are needed to confirm whether this correlation is due to differences in the numbers of retinal nerve fibers or other factors.

暂无摘要。

BACKGROUND: Phakic lenses (PIOLs, the most common and only disclosed type being the implantable collamer lens, ICL) are used in patients with large or excessive ametropia in cases where laser refractive surgery is contraindicated. The purpose of this study was to present a strategy based on anterior segment OCT data for calculating the refraction correction (REF) and the change in lateral magnification (ΔM) with ICL implantation.
METHODS: Based on a dataset (N = 3659) containing Casia 2 measurements, we developed a vergence-based calculation scheme to derive the REF and gain or loss in ΔM on implantation of a PIOL having power PIOLP. The calculation concept is based on either a thick or thin lens model for the cornea and the PIOL. In a Monte-Carlo simulation considering, all PIOL steps listed in the US patent 5,913,898, nonlinear regression models for REF and ΔM were defined for each PIOL datapoint.
RESULTS: The calculation shows that simplifying the PIOL to a thin lens could cause some inaccuracies in REF (up to ½ dpt) and ΔM for PIOLs with high positive power. The full range of listed ICL powers (- 17 to 17 dpt) could correct REF in a range from - 17 to 12 dpt with a change in ΔM from 17 to - 25%. The linear regression considering anterior segment biometric data and the PIOLP was not capable of properly characterizing REF and ΔM, whereas the nonlinear model with a quadratic term for the PIOLP showed a good performance for both REF and ΔM prediction.
CONCLUSIONS: Where PIOL design data are available, the calculation concept should consider the PIOL as thick lens model. For daily use, a nonlinear regression model can properly predict REF and ΔM for the entire range of PIOL steps if a vergence calculation is unavailable.

BACKGROUND: The purpose of this Monte-Carlo study is to investigate the effect of using a thick lens model instead of a thin lens model for the intraocular lens (IOL) on the resulting refraction at the spectacle plane and on the ocular magnification based on a large clinical data set.
METHODS: A pseudophakic model eye with a thin spectacle correction, a thick cornea (curvatures for both surfaces and central thickness) and a thick IOL (equivalent power PL derived from a thin lens IOL, Coddington factor CL (uniformly distributed from -1.0 to 1.0), either preset central thickness LT = 0.9 mm (A) or optic edge thickness ET = 0.2 mm, (B)) was set up. Calculations were performed on a clinical data set containing 21 108 biometric measurements of a cataractous population based on linear Gaussian optics to derive spectacle refraction and ocular magnification using the thin and thick lens IOL models.
RESULTS: A prediction model (restricted to linear terms without interactions) was derived based on the relevant parameters identified with a stepwise linear regression approach to provide a simple method for estimating the change in spectacle refraction and ocular magnification where a thick lens IOL is used instead of a thin lens IOL. The change in spectacle refraction using a thick lens IOL with (A) or (B) instead of a thin lens IOL with identical power was within limits of around ±1.5 dpt when the thick lens IOL was placed with its haptic plane at the plane of the thin lens IOL. In contrast, the change in ocular magnification from considering the IOL as a thick lens instead of a thin lens was small and not clinically significant.
CONCLUSIONS: This Monte-Carlo simulation shows the impact of using a thick lens model IOL with preset LT or ET on the resulting spherical equivalent refraction and ocular magnification. If IOL manufacturers would provide all relevant data on IOL design data and refractive index for all power steps, this would make it possible to perform direct calculations of refraction and ocular magnification.

UNASSIGNED: To investigate the effects of adjusting the ocular magnification during OCT-based angiography imaging on structure-function relationships and glaucoma detection.
UNASSIGNED: Cross-sectional study.
UNASSIGNED: A total of 96 healthy control participants and 90 patients with open-angle glaucoma were included.
UNASSIGNED: One eye of each patient in the control group and the patient group was evaluated. The layers comprising the macula vascular density (VD) and circumpapillary VD were derived from swept-source OCT angiography imaging. The mean sensitivity (MS) of the standard automated perimetry was measured using the Humphrey 24-2 test. Structure-function relationships were evaluated with simple and partial correlation coefficients. A receiver operating characteristic analysis was performed to evaluate the diagnostic accuracy for glaucoma using the area under the receiver operating characteristic curve (AUC). Ocular magnification was adjusted using Littmann\'s formula modified by Bennett.
UNASSIGNED: The association between the axial length and VD, structure-function relationships, and glaucoma detection with and without magnification correction.
UNASSIGNED: The superficial layer of the macular region was not significantly correlated to the axial length without magnification correction (r = 0.0011; P = 0.99); however, it was negatively correlated to the axial length with magnification correction (r = -0.22; P = 0.028). Regarding the nerve head layer in the circumpapillary region, a negative correlation to the axial length without magnification correction was observed (r = -0.22; P = 0.031); however, this significant correlation disappeared with magnification correction. The superficial layer of the macula and the nerve head layer of the circumpapillary region were significantly correlated to Humphrey 24-2 MS values without magnification correction (r = 0.22 and r = 0.32, respectively); however, these correlations did not improve after magnification correction (r = 0.20 and r = 0.33, respectively). Glaucoma diagnostic accuracy in the superficial layer (AUC, 0.63) and nerve head layer (AUC, 0.70) without magnification correction did not improve after magnification correction (AUC, 0.62 and 0.69, respectively).
UNASSIGNED: Adjustment of the ocular magnification is important for accurate VD measurements; however, it may not significantly impact structure-function relationships and glaucoma detection.

To evaluate the relationship between ocular magnification correction and macular choroidal thickness (ChT) measurements in children, and to demonstrate when ocular magnification correction is necessary.
Chinese children aged 6-9 years with various refractive statuses were included. Swept-source optical coherence tomography was used to measure macular ChT. A self-designed program was adopted to simulate ChT changes in each sector of the ETDRS grid in the macula under various simulated axial lengths (ALs).
ChT measurements were not affected for all simulated ALs in over 95% of the individuals in the central fovea. In the inferior, superior, and temporal parafoveal sectors, the extent of AL that may include 95% of the individuals narrowed from approximately 22.0 mm to 27.2 mm. In the nasal parafoveal sector and inferior, superior, and temporal perifoveal sectors, the extent of AL that may include 95% of the individuals became even narrower, from approximately 22.8 mm to 26.0 mm. The narrowest extent was observed in the perifoveal nasal sector, ranging from 23.3 mm to 25.5 mm. The effect of ocular magnification was more significant in hyperopes than in myopes in the inferior parafoveal sector and temporal, superior, and nasal perifoveal sectors.
During macular ChT measurements, ocular magnification correction is not necessary in the central fovea. However, ocular magnification should be corrected normally in the nasal perifoveal region and in individuals with ALs shorter than 22.8 mm or longer than 26.0 mm in the remaining macular regions.

BACKGROUND: Overall ocular magnification (OOM) and meridional ocular magnification (MOM) with consequent image distortions have been widely ignored in modern cataract surgery. The purpose of this study was to investigate OOM and MOM in a general situation with an astigmatic refracting surface.
METHODS: From a large dataset containing biometric measurements (IOLMaster 700) of both eyes of 9734 patients prior to cataract surgery, the equivalent (PIOLeq) and cylindric power (PIOLcyl) were derived for the HofferQ, Haigis, and Castrop formulae for emmetropia. Based on the pseudophakic eye model, OOM and MOM were extracted using 4 × 4 matrix algebra for the corrected eye (with PIOLeq/PIOLcyl (scenario 1) or with PIOLeq and spectacle correction of the residual refractive cylinder (scenario 2) or with PIOLeq remaining the residual uncorrected refractive cylinder (blurry image) (scenario 3)). In each case, the relative image distortion of MOM/OOM was calculated in %.
RESULTS: On average, PIOLeq/PIOLcyl was 20.73 ± 4.50 dpt/1.39 ± 1.09 dpt for HofferQ, 20.75 ± 4.23 dpt/1.29 ± 1.01 dpt for Haigis, and 20.63 ± 4.31 dpt/1.26 ± 0.98 dpt for Castrop formulae. Cylindric refraction for scenario 2 was 0.91 ± 0.70 dpt, 0.89 ± 0.69 dpt, and 0.89 ± 0.69 dpt, respectively. OOM/MOM (× 1000) was 16.56 ± 1.20/0.08 ± 0.07, 16.56 ± 1.20/0.18 ± 0.14, and 16.56 ± 1.20/0.08 ± 0.07 mm/mrad with HofferQ; 16.64 ± 1.16/0.07 ± 0.06, 16.64 ± 1.16/0.18 ± 0.14, and 16.64 ± 1.16/0.07 ± 0.06 mm/mrad with Haigis; and 16.72 ± 1.18/0.07 ± 0.05, 16.72 ± 1.18/0.18 ± 0.14, and 16.72 ± 1.18/0.07 ± 0.05 mm/mrad with Castrop formulae. Mean/95% quantile relative image distortion was 0.49/1.23%, 0.41/1.05%, and 0.40/0.98% for scenarios 1 and 3 and 1.09/2.71%, 1.07/2.66%, and 1.06/2.64% for scenario 2 with HofferQ, Haigis, and Castrop formulae.
CONCLUSIONS: Matrix representation of the pseudophakic eye allows for a simple and straightforward prediction of OOM and MOM of the pseudophakic eye after cataract surgery. OOM and MOM could be used for estimating monocular image distortions, or differences in overall or meridional magnifications between eyes.

BACKGROUND: Ocular magnification and aniseikonia after cataract surgery has been widely ignored in modern cataract surgery. The purpose of this study was to analyse ocular magnification and inter-individual differences in a normal cataract population with a focus on monovision.
METHODS: From a large dataset containing biometric measurements (IOLMaster 700) of both eyes of 9734 patients prior to cataract surgery, eyes were indexed randomly as primary (P) and secondary (S). Intraocular lens power (IOLP) was derived for the HofferQ, Haigis and Castrop formulae for emmetropia for P and emmetropia or myopia (-0.5 to -2 dpt) for S to simulate monovision. Based on the pseudophakic eye model in addition to these formulae, ocular magnification was extracted using matrix algebra (refraction and translation matrices and a system matrix describing the optical property of the entire spectacle corrected or uncorrected eye).
RESULTS: With emmetropia for P and S the IOLP differences (S-P) showed a standard deviation of 0.162/0.156/0.157 dpt and ocular magnification differences yielded a standard deviation of 0.0414/0.0405/0.0408 mm/mrad for the HofferQ/Haigis/Castrop setting. Simulating monovision, the myopic eye (S) showed a systematically smaller mean absolute spectacle corrected ocular magnification than the emmetropic eye (-0.0351/-0.0340/-0.0336, respectively, relative magnification around 2%). If myopia in the S eye remains uncorrected, the reduction of ocular magnification is much smaller (around 0.2-0.3%).
CONCLUSIONS: Vergence formulae for IOLP calculation sometimes implicitly define a pseudophakic eye model which can be directly used to predict ocular magnification after cataract surgery. Despite a strong similarity of both eyes, ocular magnification does not fully match between eyes and the prediction of ocular magnification and aniseikonia might be relevant to avoid eikonic problems in the pseudophakic eye.

OBJECTIVE: Aniseikonia as one of the major risk factors for asthenopic problems is mostly overlooked in modern cataract surgery. The purpose of this study was to develop a simple calculation scheme for clinicians to predict the object to image magnification in a pseudophakic eye with biometric data.
METHODS: The calculation scheme for object to image magnification in the pseudophakic eye is based on a vergence calculation of the lens power with theoretical optical formulae. From the biometric data, which are typically derived from both eyes during lens power calculation, the vergences in front of and behind the 3 or 4 refractive surfaces of the pseudophakic eye model are used to predict the magnification for objects at infinity or objects located at a finite measurement distance (e.g. 5 m).
RESULTS: With a formula-based lens power calculation a pseudophakic eye model is set up with 3 or 4 refractive surfaces (postoperative spectacle refraction; thick cornea described by anterior surface or thick cornea characterized by anterior and posterior surfaces; intraocular lens). The vergence in front of and behind each refractive surface is derived by means of linear Gaussian optics. The quotient of the product of all vergences in front of the surfaces and the product of all vergences behind the respective surfaces describes the object to image magnification of the eye. A comparison of the object to image magnification of both eyes yields the retinal image size disparity or aniseikonia. This calculation strategy is shown in a step-by-step approach exemplarily for the Haigis and Hoffer‑Q formulae (3 surfaces) and the Castrop formula (4 surfaces).
CONCLUSIONS: If during planning and lens power calculation biometry is performed for both eyes, ocular magnification of both eyes can be easily derived with this calculation scheme and aniseikonia can be extracted from a comparison of magnification of both eyes. Such a simple prediction should be established as a standard for precataract biometry and lens power calculation for early detection and avoidance of asthenopic complaints after cataract surgery.
UNASSIGNED: HINTERGRUND UND ZIELSETZUNG: Die Aniseikonie als mögliche Ursache asthenopischer Beschwerden tritt bei der modernen Kataraktchirurgie oft in den Hintergrund. Ziel der vorliegenden Arbeit ist es, dem Kliniker ein einfaches Berechnungsmodell an die Hand zu geben, mit dem der Abbildungsmaßstab des pseudophaken Auges abgeschätzt werden kann.
UNASSIGNED: Das Berechnungsschema für den Abbildungsmaßstab des pseudophaken Auges bezieht sich auf die formelbasierte (vergenzbasierte) Berechnung der Intraokularlinse mit theoretisch-optischen Formeln. Aus den biometrischen Größen, die in der Regel für beide Augen bei der Linsenberechnung vorliegen, kann aus den Vergenzen vor und hinter den 3 oder 4 refraktiven Grenzflächen im pseudophaken Augenmodell der Abbildungsmaßstab für Objekte im Unendlichen oder in einer endlichen Messdistanz ermittelt werden.
UNASSIGNED: Bei der formelbasierten Berechnung wird ein pseudophakes Augenmodell mit 3 bzw. 4 refraktiven Grenzflächen (postoperative Brillenrefraktion; dünne Hornhaut, beschrieben durch die Vorderfläche, bzw. dicke Hornhaut, beschrieben durch die Vorder- und Rückfläche; Intraokularlinse) definiert und mit den Methoden der linearen Optik die Vergenz vor und hinter jeder Grenzfläche bestimmt. Der Quotient aus dem Produkt der Vergenzen vor den Grenzflächen und dem Produkt der Vergenzen unmittelbar hinter den Grenzflächen beschreibt direkt den Abbildungsmaßstab des Auges. Aus dem Vergleich des Abbildungsmaßstabs beider Augen kann unmittelbar der retinale Bildgrößenunterschied ermittelt werden. Exemplarisch wird dies anhand der Haigis- und Hoffer-Q-Formel (3 Flächen) und der Castrop-Formel (4 Flächen) gezeigt.
UNASSIGNED: Wird bei der Planung der Kataraktoperation die Biometrie und Linsenberechnung an beiden Augen durchgeführt, so kann mit einfachen Mitteln der Abbildungsmaßstab bei beiden Augen und aus dem Vergleich beider Augen die Aniseikonie des pseudophaken Patienten ermittelt werden. Eine derartige Abschätzung sollte fester Bestandteil der Linsenberechnung werden, um mögliche asthenopische Beschwerden nach der Kataraktoperation früh zu erkennen.