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At least 127 records · Page 7Linked to original sources
PubMedDate not supplied

Implantation of a new accommodative posterior chamber intraocular lens.

PURPOSE: A new, potentially accommodative posterior chamber lens (PCIOL) was designed based on principles elaborated by Hanna using finite element computer simulation methods. We report 3-month postoperative results in patients. METHODS: In a prospective study, 12 eyes of 12 patients (age 45 to 87 yr) underwent phacoemulsification for cataracts and PCIOL implantation. The PCIOL, 1 CU, has haptics designed for anterior optic movement following ciliary muscle contraction. Patients were examined postoperatively after 1 and 2 days, 1, 2 and 6 weeks, and 3 months, and results were compared with a control group of 12 eyes that received standard PMMA or acrylic PCIOLs. RESULTS: Surgery was uncomplicated and all PCIOLs were well-tolerated and stable with good centration in the capsular bag. The results were (mean +/- SD [range] and median; 1 CU versus control PCIOL): near visual acuity (Birkhäuser reading chart at 35 cm) with best distance correction 0.34 +/- 0.17 (0.2 to 0.6), 0.3 (J10-J1, median J7) versus 0.15 +/- 0.07 (0.1 to 0.3), 0.15 (J16-J7, median J13), P=.001; subjective near point 59 +/- 10 cm (40 to 100 cm), 53.5 cm versus 93 +/- 20 cm (64 to 128 cm), 86 cm, P=.004; retinoscopic accommodative range 1.2 +/- 0.4 D (0.63 to 1.5 D), 1.2 D versus 0.2 +/- 0.19 D (-0.25 to 0.5 D), 0.25 D, P < .001; decrease of anterior chamber depth after 2% pilocarpine 0.63 +/- 0.16 mm (0.40 to 0.91 mm), 0.63 mm versus 0.15 +/- 0.05 mm (0.08 to 0.20 mm), 0.17 mm, P < .001. CONCLUSIONS: The new PCIOL appears to be safe at short to medium term. Our results indicate pseudophakic accommodation secondary to focus shift with this PCIOL. Additional larger and long-term studies are necessary for exact evaluation of safety and accommodative power of this new PCIOL.

Accommodation, Ocular↗
PubMed1976

Recent developments in automatic refraction.

A detailed description of the Ophthalmetron is given. This is an automatic refractometer using the principle of infra-red retinoscopy and having a sensitivity range from -18.00 D to +17.00 D with a resolution of 0.25 D. By means of a rapid light scan across the patient's pupil the instrument determines the direction of motion of the retinal reflex in all meridians and a movement null-point is determined electronically. Results are then plotted automatically on a chart drum. Some early validation studies have shown the Ophthalmetron to provide a refraction end-point in good agreement with conventional retinoscopic findings. The paper concludes with an appendix in which the features of three commercially available automatic refractometers are compared.

Humans↗
PubMed2000

Normal emmetropization in infants with spectacle correction for hyperopia.

PURPOSE: The development of emmetropic refraction is known to be under visual control. Does partial spectacle correction of infants' refractive errors, which has been shown to have beneficial effects in reducing strabismus and amblyopia, impede emmetropization? The purpose of the present study was to perform the first longitudinal controlled trial to investigate this question in human subjects. METHODS: Children identified as having significant hyperopia in a population screening program at age 8 to 9 months were assigned to treated (partial spectacle correction) or untreated groups. A control group of infants with no significant refractive errors at screening was also recruited. Measurements of retinoscopic refraction under cycloplegia were taken at 4- to 6-month intervals up to the age of 36 months, and changes in refraction of 148 subjects were analyzed longitudinally. RESULTS: Refractive error decreased toward low hyperopic values between 9 and 36 months in both hyperopic groups. By 36 months, this reduction of hyperopia showed no overall difference between children who were treated with partial spectacle correction and those who were not. Despite the improvement, both hyperopic groups' mean refractive error at 36 months remained higher than that of the control group. When infants in all three groups were considered together, the rate of reduction of refractive error was, on average, a linear function of the initial level of hyperopia. CONCLUSIONS: The benefits of spectacle correction for infants with hyperopia can be achieved without impairing the normal developmental regulation of refraction.

Accommodation, Ocular↗
PubMed2004

[The image futures of optical coherence tomography in pathologic myopia].

OBJECTIVE: To study the characteristics of optical coherence tomography (OCT) pictures in pathologic myopia. METHODS: 100 cases (195 eyes) of pathologic myopia were examined with OCT. The Age ranges of all the cases was 16-76 years and refraction error was -6.00 - -36.00 diopters. RESULTS: OCT image was normal in 7 eyes (4.3%), the reflectivity band of RPE and chorio-capillaries were uneven and thinning in 147 eyes (90.2%). Full-thickness macular hole was found in 21 eyes (10.8%), of which 10 (5.1%) eyes were associated with retinal detachment; local shallow retinal detachment was found in 24 eyes (12.3%), of which 7 eyes (3.6%) were associated with retinal schisis, 19 eyes (9.7%) with macular choroidal neovascularization (CNV). retinal swelling was often associated with the following diseases: Fuchs spot 9 eyes (4.6%), thick macular hemorrhage 3 eyes, epiretinal macular membrane 18 eyes (9.2%); macular sensory retina thinning in 5 eyes (2.6%). CONCLUSION: Compared with fundus examination including slit lamp with pan-retinoscope, OCT showed unique preference for observation of the changes of retinal pigment epithelium (RPE), chorio-capillary layer, diagnosis macular hole and epiretinal macular membrane, discovery of small sensory retinal detachment, schisis and thinning of sensory retina layer etc. OCT can not either discover a piece of thin macular hemorrhage or differentiation between thick macular hemorrhage and pigment spot.

Adolescent↗
PubMed2003

[Effects of nitric oxide on form-deprivation myopia in chicks].

OBJECTIVE: To construct a chick model of form-deprivation myopia (FDM) to investigate the effect of nitric oxide (NO) on FDM. METHODS: FDM was induced in 60 one-day white leghorn chicks. They were divided into group A and B. One eye was covered randomly, and the other served as control. In each week of the experimental period, the retinoscopic refraction was performed, and the axial length was measured with A-mode ultrasound. The NO concentration of retina and choroid from the control and the experimental eyes was measured using NO detection kit. Change in the expression of iNOS mRNA was measured by RT-PCR. The activity of iNOS was analyzed with immunohistochemistry. RESULTS: Form-deprivation eyes were significantly more myopic than the controls, and the axial length of occluded eyes was significantly longer than that of the controls. Unocclusion attenuated the development of myopia and inhibited the axial elongation. Form-deprivation reduced the NO concentration ,the immunoreactivity of iNOS, and the expression of iNOS mRNA. The gradual restoration of normal vision was found after uncovering the eyes. But the expression of iNOS mRNA was significantly higher than that of the controls at the first week after the unocclusion. CONCLUSION: Form-deprivation can construct an animal model of myopia. FDM is reversible before the chicks were mature. NO may be involved in the form of FDM.

Animals↗
PubMed2005

[Dynamic expression of VIPR2 in form deprivation myopia].

OBJECTIVE: To investigate the dynamic expression and significance of vasoactive intestinal peptide receptor 2 (VIPR2) on retina-choroid-clera in high myopia. METHODS: Twenty-one yellow chicks of 1 day old were used in the research. The right eyes were the experimental group, covered continuously for 1 week, 2 weeks and 4 weeks respectively. The left eyes were not covered as the normal control group. Both groups were detected diopter degrees using retinoscopic refraction, determinated eyeball axis using ophthalmology ultra-A, and investigated VIPR2 expression on retina-choroid-sclera in both groups at three stages by SP immunohistochemical staining. RESULTS: The experimental eyes changed from hypermetropia at pre-experiment to high myopia during the experiment stages, and the diopter degrees were deeper and eyeball axis was longer along with the period of being covered. Both groups had strong expression of VIPR2 on photoreceptor-outer segment of the retina and choroids. The expression was down-regulated with the time in both groups. Compared with the control group, VIPR2 expression of the experimental group was significantly up-regulated (P < 0.05). CONCLUSION: Form deprivation could induce high myopia. The expression of VIPR2 existed on photoreceptor-outer segment of the retina and choroids. VIPR2 may play an important role on the formation and development of myopia.

Animals↗
PubMed2005

[Comparison on morphology and ultrastructure of two kinds of myopic models].

OBJECTIVE: To study the possibility of inducing refractive errors by opening the mouse (C57BL/6J) eye artificially after birth and explore the difference in pathogenic mechanism in form-deprivation myopia by analyzing the histological changes of the animal eyes. METHODS: 4-day-old mice (n = 13) was undergone 10-day monocular artificially opened period till the opposite eye was natural open. Another group 12-day-old mice (n = 13) were raised with monocular suture of eyelid for 7 days. Age-matched untreated mice were used as control. Retinoscopic refraction was performed subsequently. Animals were sacrificed and the eyes enucleated at the end of the experiment. The axial length and weight of the eyes were measured and the sections of the eyes were also observed by light and electron microscope. RESULTS: All eyes treated with two methods showed significant development of myopia compared with the contralateral eye. The axial length was elongated in form deprived eyes, but it was shortened in artificially opened eyes; no change in the weight of eyeball was found in form deprived eyes, but it was reduced in artificially opened eyes when compared with corresponding fellow eyes. Under light microscope, there is no significant histological difference observed in the eyes treated with two methods. Under electron microscope, rod outer segment in form deprived eyes was inordinate and the phagosomes containing fractions of the membrane disc of outer segment were remarkably decreased. No significant changes of photoreceptor were demonstrated in artificially opened eyes. CONCLUSION: The means of artificially opening eyelid can induce myopia in the mouse and the method may be useful to establish myopia animal model.

Animals↗
PubMedDate not supplied

Refractive error profile--a clinical study.

AIM: To study the distribution of refractive error in different ethnic groups of Nepal. METHODS: A total of 1276 new eye patients between 5-35 years of age were included in this study after a thorough eye examination consisting of vision test, anterior and posterior segment eye examination including the investigative procedures whenever needed to rule out any systemic and ocular diseases. Thereafter, the patients were subjected to rigorous streak retinoscopic refraction. RESULTS: Out of 1276 eye patients examined 51.33 % patients are males and 48.66 % are females. The ethnic distribution of refractive error shows that there are 32.44% Newars; 27.50% Brahmins; 21.63% Chhetriyas; 12.14% Gurungs, Magars, Rais, Limbus, Tamangs, Sunuwars; and 6.26% Madhesias. Out of 414 Newar patients, 14.00% patients are myopic; 29.71% hyperopic; and 56.28% astigmatic. In 351 Brahmin patients, 14.81% patients are myopic; 49.85% hyperopic; and 35.32% astigmatic. In 276 Chhetry patients, 13.40% patients are myopic; 48.18% hyperopic; and 38.40% astigmatic. Out of 155 Gurungs, Magars, Rais patients, 11.61% are myopic; 52.90% hyperopic; and 35.48% astigmatism. Out of 80 Madhesias patients, 11.25% are myopic; 37.50% hyperopic; and 51.25 % astigmatic. CONCLUSION: Thus, a refractive error profile is drawn up in Nepalese population.

Adolescent↗
PubMed2006

[Risk factors for cardiovascular autonomic neuropathy and their prognostic implications in type 2 diabetes mellitus].

OBJECTIVE: Risk factors for diabetic cardiovascular autonomic neuropathy (CAN) in patients with type 2 diabetes were analyzed to establish a regression model for evaluating the diagnosis of CAN. METHODS: 325 patients with type 2 diabetes were divided into four groups according to the results of four standard function tests. Every patient was required to offer detailed disease history and accept physical examination, serum and urine tests and examinations including ECG, nerve conduction velocity, retinoscope and Doppler of carotid and lower limb arteries. RESULTS: 64.0% of the patients had abnormal autonomic function and 30.2% definite CAN. There was significant difference among groups about age, average glycosylated forms of hemoglobin (HbA1c), systolic blood pressure, corrected 24 h albumin excretion and heart rate at rest (P < 0.001). The incidence of diabetic complications and accompanying diseases increased with deterioration of CAN (P < 0.05). The regression model showed that age, average HbA1c, hypertension, peripheral neuropathy, retinopathy, tachycardia at rest and duration of peripheral neuropathy were significant related factors for CAN. With these factors, a mathematic formula was established which could be used for evaluating the diagnosis of CAN. CONCLUSION: Except for age and hypertension, risk factors were all induced by hyperglycemia. It is suggested that control of hyperglycemia is of primary importance in preventing diabetic complications.

Adult↗
PubMed1991

Ophthalmologic screening of adults with mental retardation.

Ophthalmological screening was conducted on 113 clients in a work activity center for adults with mental retardation. Thirty-two percent had abnormalities that were neither refractive nor strabismic. We encountered no instance of neglect of current organic ocular disease. However, 37% of clients had at least one eye that either was not within one diopter of emmetropia or that was not corrected to within one diopter of their retinoscopic findings. Ophthalmologists should consider providing screenings in settings familiar to such clients, where they are more likely to be cooperative.

Adult↗
PubMed1987

Detection of congenital cataracts and other ocular media opacities.

Congenital cataracts and other ocular media opacities are a leading cause of preventable childhood blindness. Because of the importance of early recognition and treatment of congenital media opacities in newborn infants, we designed a study to determine the ability of relatively inexperienced examiners to detect such ocular abnormalities with either of two instruments. Eight third-year medical students examined eight children and young adults with ocular media opacities and eight age-matched normal subjects with an ophthalmoscope or a retinoscope. With respect to detection of abnormalities requiring referral to an ophthalmologist, there was an underreferral rate of 7% and overreferral rate of 5%. There was no significant difference between instruments. Based on an estimated incidence of congenital cataracts of 0.4%, the positive predictive value of this screening in the population of newborn infants is 18.7% and the negative predictive value is 99.96%. Therefore, overreferral is unavoidable in the effort to detect infants with congenital media opacities. We conclude that this examination can be easily taught and accurately performed with the readily available ophthalmoscope. The importance and technique of examining the red reflex should be stressed in the training of those caring for newborns.

Cataract↗
PubMed1985

Environmental influence on shape of the crystalline lens: the amphibian example.

Amphibians are faced with the problem of adapting to aerial vision when undergoing metamorphosis. The rate and extent of ocular change has been examined in five species with widely varying life histories. Ocular effects and in particular lens shape changes were determined from measurements of gross anatomy at various metamorphic stages using a freeze-sectioning technique. In addition, refractive states were measured retinoscopically in air and water where possible. All larval animals have the ocular structure and optics typical of teleost fish. Adults show varying levels of adaptation to aerial vision, depending on the degree of departure from an aquatic style of behavior. In certain cases the spherical aquatic shape of the lens is maintained while in others, lens shape is altered markedly to a flattened elliptical form. Histological study indicates that change in lens shape is brought about by a rapid increase of mitotic activity of equatorial epithelial cells at critical periods during metamorphosis.

Adaptation, Physiological↗
PubMed1986

Keratoconus: the clinical spectrum.

This paper reports observations made on 57 keratoconus patients, 32 women and 25 men. Particular attention is paid to the retinoscopic reflex, intraocular pressure, and the patient's bodyweight. Diagnostic criteria are proposed.

Adult↗
PubMed1985

Optics of photoretinoscopy: results from ray tracing.

Recent photographic studies have generated renewed interest in the optics of the retinoscopic (skiascopic) image. In photoretinoscopy the subject's eye is illuminated by a point source of light and the fundal image of this light at the plane of the subject's pupil is observed or photographed from a position near the source. The image so obtained is a function of the dioptric defocus of the eye relative to the camera, D, the distance of the source and camera from the eye, A, the radius of the subject's pupil, R, and the distance of the point source from the edge of the camera aperture, E. The fraction of the subject's pupil which is not filled with light is termed the "Dark Fraction" (DF) and may be computed from a simple ray tracing model of the eye. It is given in terms of the above parameters by the equation DF = E/(2ARD). The validity of this equation was tested with a photoretinoscope and artificial eye. The photoretinoscope, which is a novel modification of an isotropic photorefractor, is also described.

Humans↗
PubMed1984

Automated objective refractometers.

We have shown how the modern-day analysis of the aerial image produced by an indirect ophthalmoscope forms the basis for automated objective refraction. Objective automated optometers present with the advantages that they: record rapidly, thereby minimizing the effects of accommodative fluctuation and/or fixation instability, demand only low-level technical skill on the part of the operator, demand little of the patient beyond passive cooperation. Refractive findings obtained using objective automated refractors are counterparts of retinoscopic prescriptions and correlate about as well with subjective findings as do those obtained by the proficient retinoscopist.

Ophthalmoscopy↗
PubMed1983

Development of a contact lens for refracting aquatic animals.

Development of a new technique for refracting the eye of unwieldy and large aquatic organisms in air is presented. The technique employs a contact lens to simulate underwater conditions. Refraction is performed through a flat front surface with an ophthalmoscope or a streak retinoscope. Data from 11 carcharhinid sharks (four species) indicate that the smaller eyes of inshore species are defocused relative to the eyes of offshore species.

Animals↗
PubMed1978

Optical characteristics of the eye of the spiny dogfish (Squalus acanthias).

On the basis of the failure of attempts to induce refractive accommodation changes electrically and with drugs, it appears that the eye of the spiny dogfish (Squalus acanthias) lacks the capacity to accommodate. Retinoscopic measurements indicate moderate hyperopia (+6D). However, measurements made with light restricted to the short end of the visible spectrum indicate only one or two dioptres of hyperopia and it is possible that the latter measurements are more coincident with natural conditions. In contrast to the somewhat flattened lens of other elasmobranchs the lens of the spiny dogfish is nearly spherical. The fact that its refractive index is high (1.66) suggests that the static optical system of this eye is very similar to that of the teleosts.

Accommodation, Ocular↗
PubMed1982

Measurement of accommodative amplitude in amblyopia.

Monocular accommodative amplitudes were measured in amblyopic individuals by the subjective minus lens and push-up techniques and by objective dynamic retinoscopy. Accommodative amplitudes were always reduced in amblyopic eyes using the minus lens and retinoscopy techniques, but not with the push-up technique which inflated this measure. Owing to difficulty in detecting defocused stimuli with the amblyopic eye, it is suggested that the objective retinoscopic technique be used by clinicians for accurate assessment of accommodative amplitude in these patients.

Accommodation, Ocular↗