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At least 19 recordsLinked to original sources
PubMed1979

Axial length of the emmetropic eye and its relation to the head size.

The results of the ultrasonographic measurements of the ocular components in 40 emmetropic eyes from men of nearly the same age are presented and the possible relation between the axial eye length and the head size is discussed. A significant correlation was found between the axial eye length and the head circumference (P less than 0.001), between the axial eye length and the head length (P less than 0.01) and between the axial eye length and the head breadth (P less than 0.02). A significant correlation was also found between the axial eye length and the height of the subjects (P less than 0.01). It is suggested that such a correlation can explain not only the wide individual range of axial eye lengths in emmetropic eyes, but also the existing difference in axial eye length between the sexes. The mean eye length was 23.82 mm in 40 men and 23.02 mm in 10 women; both sexes were of the same age (20-30 years).

Adult↗
PubMed1977

Comparison of ultrasonic and photographic methods of axial length measurements of the eye.

The axial length of 25 eyes was measured by the photographic method and by ultrasonography. The photographic measurements were consistently larger than the ultrasonic, but analysis gave a correlation coefficient of r = 0-8483. The results suggest that the centre of rotation of the eye lies posterior to the anatomical centre of the globe. Using an empirical method of calculation and allowing for an error of +/-0-3 mm in the ultrasonic measurement, the photographic results were within +/-0-5 mm in 13 eyes and +/-1-0 mm in 7 eyes. The photographic method may be helpful as a guide to the power of intraocular lens implants and for comparing axial lengths in population studies.

Anthropometry↗
PubMed1977

Ultrasonographic study of 100 emmetropic eyes.

The results of the ultrasonographic measurements of the ocular components in 100 emmetropic eyes of nearly the same age, are presented and the possible relations between the various ocular parameters are discussed. A definite correlation was found (1) between the eye length and the curvature radius of the anterior corneal surface; (2) between the eye length and the anterior chamber depth, and (3) between the eye length and the vitreous length. No correlation could be demonstrated between the lens thickness and the eye length. This fact shows that in the wide range of axial eye lengths in emmetropic eyes, the emmetropization effect of the lens can only be provided by a change in the curvature radius of the lens surfaces. The mean eye length of 100 emmetropic eyes was 23.37 mm.

Adult↗
PubMed1979

Ultrasonographic study on changes in axial eye dimensions after encircling procedure in retinal detachment surgery.

The pre- and postoperative results of ultrasonographic measurements on the axial ocular components in 10 phakic eyes with retinal detachment treated with encircling silicone rubber band are presented. A significant increase (P less than 0.001) in axial eye length from 0.62 to 1.24 mm (average: 0.98 mm) was found. The elongation of the eye was caused by a corresponding increase in the length of the vitreous cavity. No significant changes were found in the anterior segment of the eyes. These data demonstrate that the postoperative refractive change in a myopic direction, which an encircling procedure with moderate indentation often produces, is caused by an axial elongation of the eye.

Adolescent↗
PubMed1978

Optic disc cupping and prematurity. Large cups as a possible low birth weight sequel.

In a previous ophthalmic study of ex-prematures around the age of 10 years it was accidentally found that cupping of the optic disc was significantly more pronounced in children of a low birth weight (less than 2000 g) than in full-term controls (Fledelius 1976). This was true for cup size (cup/disc diameter ratio) as well as depth (as indicated by a visible cribriform plate). The present analyses make up an extension of the above study, with additional calculations based on some of its data. Within the ex-prematures (n = 268) the cup size did not seem to be related to birth weight, sex, or visual acuity. Eyes with myopia of prematurity were not especially 'loaded' with large cups. For the whole sample (including the 187 full-term control there was a weak association between cup size and refraction (and axial eye length). Larger cups occurred relatively more often in myopic eyes. Possible mechanisms behind early changes in disc are discussed (astroglial hypothesis--distension of disc--loss of retinal nerve fibers). It is felt that this new observation--large disc cupping as a possible low birth weight sequel--has to be substantiated by further clinical evidence, as statistical type 1 error (mass significance) cannot be ruled out.

Child↗
PubMed1979

Increase in axial length of the macaque monkey eye after corneal opacification.

The cornea of one eye was opacified in two young macaque monkeys by multiple stromal injections of a suspension of polystyrene particles (latex). Ultrasound measurements showed that the eye with opaque cornea grew at a faster rate, so that after 1 year it was more than 1 mm longer than the normal eye. This difference in axial length was due to elongation of the posterior segment, since lens thickness, depth of anterior chamber, and corneal curvature were identical in both eyes. At histological examination, no pathological changes were observed in the anterior segment of the latex-injected eye except for a scant vascularization of the corneal opacity. The result of this experiment demonstrates that opacification of the corneal has effects on axial length similar to, although less marked than, those on lid fusion and therefore supports our previous conclusion that the myopia caused by lid fusion is triggered by the abnormal visual impact and involves central visual pathways.

Animals↗
PubMed2025

Intraocular pressure is a promising target for myopia control.

BACKGROUND: Myopia presents a noteworthy global health concern, urging exploration of innovative treatments. The role of intraocular pressure (IOP) in regulating the progression of myopia has been controversial. METHODS: To investigate the impact of reducing IOP to varying extents on myopia progression, three groups receiving distinct IOP-lowering medications (Brinzolamide, Latanoprost, and a combination of Brinzolamide and Latanoprost) were designed in a form-deprived myopic guinea pig model. Additionally, proteomics analyses were conducted to identify differentially expressed proteins in the sclera. RESULTS: Based on 24-h and 4-week IOP monitoring, the group receiving both Brinzolamide and Latanoprost exhibited the greatest magnitude of IOP reduction and the most significant inhibition of axial length (AL) growth. Moreover, the administration of IOP-lowering medications increased choroidal thickness and induced alterations in the structure of scleral collagen fibrils. Notably, scleral proteomics revealed remodeling processes associated with key mechanisms, including proteolysis, fibrinolysis, and metal ion binding. CONCLUSIONS: Our findings highlight that pressure-dependent scleral remodeling contributes to the deceleration of AL elongation. These results underscore the efficacy of IOP reduction in mitigating the progression of myopia, providing a promising alternative strategy for myopia management.

Myopia↗
PubMed1979

Ultrasonic measurements of the eye in the newborn infant.

The right eyes of 28 newborn infants have been examined retinoscopically, and the anterior chamber depth, the lens thickness and the length of the virteous were measured by ultrasound. In 15 of the infants keratometry was performed using the Javal-Schiötz keratometer. The total axial length of the eye was found to be longer the heavier the weight of the baby, whereas the lens thickness showed no correlation to the total axial length or to the weight of the baby. In only 1/3 of the babies was the corneal astigmatism less than 0.5 D. A significant correlation (P less than 0.01) was found between the total axial length of the eye and the length of the corneal radius.

Anterior Chamber↗
PubMed2026

Risk Factors and Predictive Model for Postoperative High Myopia in Children Undergoing Congenital Cataract Surgery With Intraocular Lens Implantation.

PURPOSE: To identify risk factors associated with the development of high myopia following congenital cataract surgery and to establish a robust predictive model. DESIGN: Retrospective clinical cohort study. SUBJECTS: This retrospective study included 106 pediatric patients who underwent congenital cataract surgery with primary IOL implantation (mean follow-up 8.19 years). The model was externally validated in an independent cohort of 72 patients with a mean follow-up of 7.83 years. METHODS: Preoperative and postoperative ocular biometric parameters were collected. Risk factors for postoperative high myopia were analyzed using Cox proportional hazards regression, which served as the basis for model construction. The predictive performance of the model was rigorously evaluated for discrimination and calibration. Discriminative ability was quantified using Harrell's C-index and the area under the receiver operating characteristic curve (AUC). Model calibration was assessed via calibration plots by comparing predicted probabilities with actual observed outcomes. Internal validation was performed using a bootstrapping method (500 iterations) to ensure model stability and adjust for potential overfitting. RESULTS: An initial postoperative refraction of <+0.75D, and a higher IOL Power to Axial length Ratio (IOL/AL ratio) were identified as significant risk factors for the development of postoperative high myopia. Shorter preoperative axial length was associated with a greater magnitude of postoperative myopic shift. The predictive model demonstrated robust performance, achieving a C-index of 0.711 (internal validation C-index: 0.713). The area under the receiver operating characteristic curve (AUC) values for predicting high myopia at 5 and 10 years were 0.858 and 0.745, respectively. Furthermore, calibration curves demonstrated excellent agreement between the predicted and observed outcomes throughout the follow-up period. In external validation, the model achieved a C-index of 0.825, 5-year AUC of 0.833, and 10-year AUC of 0.713. CONCLUSIONS: Our analysis established that initial postoperative refraction <+0.75D, and an elevated IOL/AL ratio are key determinants of high myopia risk following surgery. Shorter preoperative axial length was associated with a greater magnitude of postoperative myopic shift. This predictive framework provides clinicians with a practical tool to optimize preoperative IOL selection and identify high-risk infants who require vigilant myopia prevention and balanced amblyopia management.

Humans↗
PubMed1977

Axial length changes after retinal detachment surgery.

A-scan echography was an accurate method for detecting changes in the depth of the anterior chamber, lens thickness, and length of the vitreous cavity after retinal detachment surgery in 30 eyes. Approximately 60% of the eyes had significant alterations in axial lengths exceeding+/-0.36 mm in aphakic eyes and +/-0.54 mm in phakic eyes. However, the operation of scleral bucklingg with large segments of hard silicone rubber implants or explants supported by an encircling band failed to result in a significant predictable shift of axial change in phakic or aphakic eyes. A-scan echography showed significant shallowing of the anterior chamber, and scleral buckling significantly increases lens thickness for at least six weeks. This induced a minor myopic refractive change that may explain some of the difference in postoperative refracitons between phakic and aphakic eyes.

Astigmatism↗
PubMed2026

Axial Length Adjustment and AL/R Ratio Optimization of IOL Power Calculation in Extremely Long Eyes.

PURPOSE: To evaluate the accuracy of modern intraocular lens (IOL) power calculation formulas and axial length (AL) adjustment methods in eyes with AL &#x2265; 30.0 mm. DESIGN: Retrospective consecutive cross-sectional study. PARTICIPANTS AND CONTROLS: A total of 308 eyes (308 patients) with AL &#x2265; 30.00 mm were included. METHODS: Accuracy of modern online formulas, alone or with established AL adjustments methods, was analyzed. Subgroup analyses were performed based on AL, keratometry (K), anterior chamber depth (ACD), lens thickness (LT), and AL-to-corneal radius (AL/R) ratio. MAIN OUTCOME MEASURES: Predictive accuracy was evaluated using the formula performance index (FPI), root mean square absolute prediction error (RMSAE), standard deviation (SD) of prediction error (PE), and percentage of eyes within &#xb1;0.25 and &#xb1;0.50 diopters (D). RESULTS: Overall, Holladay 1 combined with the nonlinear polynomial Wang-Koch axial length adjustment (H1-PWK) demonstrated the best overall performance, achieving the lowest SD (0.40), RMSAE (0.40), and highest FPI (0.494). A tendency toward hyperopic error was observed in eyes with AL &#x2265; 32.0 mm, K &#x2265; 46.0 D. The AL/R ratio showed a significant positive correlation with PE in the Ladas Super formula, Barrett Universal II, EVO, PEARL-DGS, and Hoffer QST formulas. Spline-based regression analysis indicated that the transition point of AL/R from myopic to hyperopic PE varied across different formulas. CONCLUSIONS: H1-PWK provides robust refractive accuracy in extremely long eyes. The AL/R ratio may provide a useful composite biometric stratification parameter compared to AL alone.

Humans↗
PubMed1978

Visual acuity for single lines as a function of hue and age.

176 students in grades 2-12 were tested for visual acuity as a function of minimally resolvable red, yellow, green, and blue lines. A 3-way mixed analysis of variance revealed significant differences among the colors, with better acuity for longer wavelengths. Significant age effects as well as a sex X condition interaction were also found. Post hoc analysis revealed a significant quartic trend for age. It is argued that the differential acuity thresholds for hue and the curvilinear age trend may depend upon the coordination of the accommodation and refractive power of the eye, which are affected by differential growth rates of the lens and the axial length of the eye.

Accommodation, Ocular↗
PubMed1978

Axial length and the Hirschberg test.

Axial lengths of 30 eyes (15 subjects), measured by ultrasonography, ranged from 20.6--26.3 mm. Using a fixed light source, each eye was photographed as monocular fixation was changed over an 8-deg range in 2-deg steps. Hirschberg ratios obtained from the photographs show a low correlation with axial length (0.07), and the mean value, 24 prism diopters per millimeter (S.D. = 7), further supports recent recommendations that the traditional ratio of 12 or 14/1 be replaced by a more correct ratio of 22/1.

Adult↗
PubMed1978

Extreme myopia produced by modest change in early visual experience.

Chicks whose vision was restricted to the frontal visual field became extremely myopic (mean, -10 diopters; maximum, -24 diopters) and had eyes of increased axial length. Animals restricted to lateral field vision did not differ from normal animals. Monocular deprivation of form vision also produced myopia and eye enlargement and, in addition, produced increased anterior chamber depth.

Animals↗
PubMed1979

Clinical evaluation of an inexpensive ultrasound oculometer for ocular biometry.

We measured anterior chamber depth and axial length in 200 human eyes with the Echo-Oculometer and the Digital Biometric Ruler. There was good agreement between measurements with the two instruments. The echo-Oculometer is much less expensive than any other instrument available for measuring ocular axial length and satisfactorily provides information for calculation of power of intraocular lenses.

Anterior Chamber↗