Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Hyperopia”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,315 records · Page 73Linked to original sources
PubMed1978

Clinical evaluation of the 6600 Autorefractor.

The 6600 Autorefractor was evaluated on 200 patients undergoing refraction. The automatic refractor showed a high degree of accuracy in determining the needed refractive correction, but the errors are sufficient that the automatic refractor alone without subjective refinement cannot be substituted for conventional complete refracting methods with subjective refinement. However, for aphakic patients and for patients with clear media and cylindric corrections over 0.50 diopters, the automatic refractor can be used as a substitute for retinoscopy in determining the starting point for a subjective refraction.

Adolescent↗
PubMed1980

Vortex vein decompression for nanophthalmic uveal effusion.

Uveal effusion in nanophthalmic eyes probably is the result of choroidal congestion secondary to imparied vortex venous drainage through the thick sclera that is characteristic of nanophthalmos. Ten eyes with nonrhegmatogenous retinal detachment, occurring in nanophthalmic eyes, were treated by vortex vein decompression and, in some cases, drainage of choroidal and/or subretinal fluid with air injection into the vitreous cavity. Eight of the ten eyes showed reattachment of the retina after this procedure. There results support the hypothesis that choroidal congestion is the basic mechanism of nanophthalmic uveal effusion.

Aged↗
PubMed1985

Changes of refraction in schoolchildren.

The refractions of 1,118 children, aged 7 to 15 years, were followed for one to eight years; 260 children were hyperopic and 828 were myopic throughout the observation time. Thirty additional hyperopic children became myopic during follow-up. In the cross-sectional study, the mean annual change of refraction in hyperopic children varied from -0.03 to -0.11 diopters in different age groups. In myopic children, the variation was from -0.46 to -0.93 D. In the longitudinal follow-up study (from five to eight years), the mean annual change of refraction in hyperopic children was -0.12 D compared with -0.55 D in myopic children. The mean annual change in the 30 hyperopic children who became myopic was -0.21 D while hyperopic and -0.60 D while myopic. The difference is highly significant. It clearly shows that the changes of refraction in hyperopic schoolchildren occur much more slowly than in myopic children of the same age.

Adolescent↗
PubMed1987

Intraocular pressure by noncontact tonometry with and without soft contact lenses.

We compared the intraocular pressure of 43 eyes (23 patients) with and without soft contact lenses. Two measurements were taken on each eye while the patients were wearing their soft contact lenses, and then immediately after the lenses were removed. Intraocular pressure measurements were taken by noncontact tonometry. The results showed that the power of the contact lens was a significant predictor of the change in intraocular pressure. In addition, when the 43 eyes were broken down into two groups, those with hyperopic lenses and those with myopic lenses, the difference in intraocular pressure was significantly larger for the group with hyperopic lenses than for the group with myopic lenses.

Contact Lenses, Hydrophilic↗
PubMed1987

Intraocular lens style and refraction in eyes treated with silicone oil.

The comparatively high refractive index of silicone oil significantly alters the refractive power of the human eye when it is placed into the vitreous cavity during retinal reattachment surgery. If cataract extraction and intraocular lens (IOL) implantation are subsequently performed, significant refractive errors result with most IOL styles if standard formulas are used to determine lens power. Thick-lens optical analysis of four IOL styles showed that the meniscus style yields the smallest difference between predicted (Binkhorst, Sanders-Retzlaff-Kraff formulas) and actual postoperative refraction. This IOL style also minimizes the change in refractive error that accompanies subsequent alterations in the contents of the vitreous cavity, including removal of silicone oil and replacement with balanced salt solution.

Eye↗
PubMed1997

Natural and imposed astigmatism and their relation to emmetropization in the chick.

This study investigated the ocular response of young chicks to astigmatic errors imposed by spectacle lenses and as a related issue, we examined the nature and prevalence of astigmatism in young chicks, and its relation to corneal development and natural emmetropization. Normal hatchling chicks exhibited significant against-the-rule refractive astigmatism (approx. 8 D) of which 60-90% was corneal. Both types of astigmatism decreased in magnitude with normal corneal development as part of emmetropization. The apparent association with corneal growth is consistent with two further observations: (1) that smaller corneas, induced by constant light rearing, had higher than normal astigmatism (1.5 D greater at 15 days), (ii) that enlarged corneas, due to form deprivation, had reduced astigmatism (2.4 D less). When astigmatism was artificially imposed with (+/-10 DC spectacle lenses), altered ocular growth patterns were observed, although the changes were not consistent with the chicks having emmetropized to the imposed astigmatism. Irrespective of the axis setting used in positioning the lenses (45 degrees, 90 degrees, 180 degrees), eyes became hyperopic with +10 DC lenses (+8.8 +/- 1.3 D), and became slightly myopic with 10 DC lenses (-1.8 +/- 1.9 D). These refractive changes are consistent with the chicks having emmetropized to the more myopic meridian rather than the equivalent mean spherical error imposed (responses of control groups to +5 D and -5 D spherical lenses were +5.2 +/- 1.0 D and -5.1 +/- 0.8 D resp.). The same was true for chicks first prevented from accommodating by prior ciliary nerve section, except for one group wearing the 10 DC lens at 45 degrees axis where astigmatic changes consistent with partial compensation were seen, although this may represent an artefact of the surgery. These results argue against 'astigmatic emmetropization' as a normal phenomenon. Also consistent with this finding was the lack of significant astigmatic changes with accommodation-stimulating and inhibiting drugs (nicotine and vercuronium resp.), for normal chicks. These results imply that accommodation, while the most likely mechanism for astigmatic emmetropization, has little capacity to compensate for imposed astigmatic focussing errors.

Accommodation, Ocular↗
PubMed2000

Choroidal retinoic acid synthesis: a possible mediator between refractive error and compensatory eye growth.

Research over the past two decades has shown that the growth of young eyes is guided by vision. If near- or far-sightedness is artificially imposed by spectacle lenses, eyes of primates and chicks compensate by changing their rate of elongation, thereby growing back to the pre-lens optical condition. Little is known about what chemical signals might mediate between visual effects on the retina and alterations of eye growth. We present five findings that point to choroidal retinoic acid possibly being such a mediator. First, the chick choroid can convert retinol into all-trans-retinoic acid at the rate of 11 +/- 3 pmoles mg protein(-1) hr(-1), compared to 1.3 +/- 0.3 for retina/RPE and no conversion for sclera. Second, those visual conditions that cause increased rates of ocular elongation (diffusers or negative lens wear) produce a sharp decrease in all-trans-retinoic acid synthesis to levels barely detectable with our assay. In contrast, visual conditions which result in decreased rates of ocular elongation (recovery from diffusers or positive lens wear) produce a four- to five-fold increase in the formation of all-trans-retinoic acid. Third, the choroidal retinoic acid is found bound to a 28-32 kD protein. Fourth, a large fraction of the choroidal retinoic acid synthesized in culture is found in a nucleus-enriched fraction of sclera. Finally, application of retinoic acid to cultured sclera at physiological concentrations produced an inhibition of proteoglycan production (as assessed by measuring sulfate incorporation) with a EC50 of 8 x 10(-7) M. These results show that the synthesis of choroidal retinoic acid is modulated by those visual manipulations that influence ocular elongation and that this retinoic acid may reach the sclera in concentrations adequate to modulate scleral proteoglycan formation.

Animals↗
PubMed1979

Pathologico-optic approach to cataract and lens.

From the weight of the lenses of patients with senile cataract, ultrasonic measurements of the eyes of patients with acute diabetic refractive changes, and calculations on the basis of Legrand's theoretical eye, it appears that the conclusion can be drawn that these refractive changes are due to alterations in the refractive indices of the lens.

Acute Disease↗
PubMed1982

Intraocular pressure in myopic anisometropia.

The authors studied the intraocular pressure, scleral rigidity and outflow facility of 137 anisometropic subjects with unilateral high myopia. The contralateral eyes were emmetropic, hyperopic or slightly myopic (less than 5 diopters). No difference was found between the intraocular pressure on the two sides. The scleral rigidity was lower and the outflow facility higher on the myopic side. It is concluded that high myopia is not, in itself, a cause of ocular hypertension, nor is caused by it.

Adolescent↗