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PubMedDate not supplied

Neovascular glaucoma. Current management.

Neovascular glaucoma is one the most difficult forms of glaucoma to treat successfully. Recent advances modifying filtration surgery can result in up to 77% success. Utilization of anterior and posterior segment photocoagulation can maintain an open angle in up to 80% of eyes when they are treated prior to angle closure by peripheral anterior synechiae. Destruction of the ciliary body can be performed more selectively utilizing argon and ruby lasers. This paper presents a rational approach to the management of neovascular glaucoma incorporating these recent advances.

Ciliary Body↗
PubMed1983

Behavioral studies on the effect of abnormal early visual experience in monkeys: spatial modulation sensitivity.

Spatial modulation sensitivity functions have been investigated by behavioral methods in two monkeys reared with normal visual experience and 12 monkeys reared with abnormal, early visual experience. Experimental treatments were initiated when the animals were approximately one month of age. Two monkeys were each treated with one of the following procedures: (1) long-term monocular lid suture, (2) short-term monocular lid suture, (3) surgically induced esotropia, (4) surgically induced exotropia, (5) optical dissociation of binocular vision with ophthalmic prisms, or (6) chronic monocular cycloplegia. The results of the studies showed a severe loss of contrast sensitivity of the treated eyes compared to the control eyes for monkeys reared with monocular lid suture or surgically induced esotropia. Surgically induced exotropia resulted in a moderate reduction in sensitivity of the deviated eye while optical dissociation resulted in a mild reduction in sensitivity of one eye compared to the other. One of the two monkeys reared for seven months with chronic monocular cycloplegia had a relative reduction in contrast sensitivity of the treated eye, but the other monkey had equal sensitivities in the two eyes. However, binocular summation experiments showed that even though the relative difference between the monocular sensitivities was small or absent for the monkeys reared with optical dissociation or chronic monocular cycloplegia, none of them demonstrated binocular vision in these experiments.

Amblyopia↗
PubMed1983

Behavioral studies on the effect of abnormal early visual experience in monkeys: temporal modulation sensitivity.

Temporal modulation sensitivity functions were investigated by behavioral methods in two monkeys reared with normal visual experience and 12 monkeys reared with abnormal early visual experience. Experimental treatments were initiated when the animals were approximately one month of age. Two monkeys were each treated with one of the following procedures: (1) long-term monocular lid suture, (2) short-term monocular lid suture, (3) surgically induced esotropia, (4) surgically induced exotropia, (5) optical dissociation of binocular vision with ophthalmic prisms, or (6) chronic monocular cycloplegia. The temporal modulation sensitivity functions for uniform field flicker for both eyes of the control subjects and for the untreated eyes of the experimental subjects were similar to functions for humans measured on the same apparatus using the same behavioral procedures. All eight of the monkeys preconditioned by lid suture or surgically induced strabismus showed reduced sensitivity at all temporal frequencies with the difference between the experimental and control eyes being larger for the high than low temporal frequencies. The monkeys reared with optical dissociation of binocular vision or chronic monocular cycloplegia showed equal temporal modulation sensitivities of the two eyes, but failed to show binocular summation. It was concluded from these studies that abnormal early visual experience in monkeys results in deficiencies in the processing of both spatial and temporal information, but the differences between the treated and untreated eyes were usually greater in the spatial domain than the temporal domain.

Amblyopia↗
PubMed1986

The longitudinal chromatic aberration of the human eye, and its correction.

The human eye suffers from longitudinal chromatic aberration, and this has been thought to average approximately 1.75 D between 420 and 660 nm. In many vision experiments the aberration may be a serious problem, and a number of lenses have been designed to correct it, two of which have recently been commercially available. These achromatising lenses produce an equal but opposite aberration to that of the average eye, and the power of the eye/lens combination should then be independent of wavelength. Recent measures of the eye's longitudinal aberration suggest that the average may be substantially greater than the above value, in which case lenses based on this figure should be inadequate. Using a Badal optometer we determined the far points for 20 subjects with each of the recent lenses, and without either, at nine wavelengths over the above range. Consistent with the early studies we found an average aberration of 1.82 D (SD 0.15 D). Both lenses performed as specified, and none of our subjects had over 0.48 D of residual aberration when corrected with either.

Adult↗
PubMed1987

Light and aging effects on vitamin E in the retina and retinal pigment epithelium.

Experiments were performed to determine the effects of senescence and light adaptation on vitamin E levels in the neural retina and RPE-choroid-sclera of pigmented rats. Aging resulted in significant increases in alpha-tocopherol levels in both tissues, the effect being most pronounced in the RPE-choroid-sclera. The state of light adaptation had no influence on alpha-tocopherol levels in the neural retina at any of the ages examined, whereas in the RPE-choroid-sclera, alpha-tocopherol levels were substantially higher in light-adapted than in dark-adapted animals at all three ages (12, 22, and 32 months) at which they were measured. The effect of light adaptation on RPE-choroid-scleral alpha-tocopherol levels was most pronounced in the oldest age group.

Adaptation, Ocular↗
PubMed1987

Contrast sensitivity and visual acuity of the pigmented rat determined electrophysiologically.

The contrast sensitivity function of the rat was assessed by investigating the relationship between the amplitude of visually evoked cortical potentials (VECP) and the spatial frequency and contrast of grating stimuli. Pattern reversal VECPs were recorded in Area 17 in the region of representation of the central binocular visual field. Transient responses were obtained with a 1 Hz contrast reversal. The mean contralateral monocular CSF peaked around 0.1 c/deg, with a threshold sensitivity of 20-25, low frequency attenuation and a high frequency cut-off of 1.18 c/deg. The mean binocular CSF showed a cut-off of 1.20 c/deg, which matches several behavioural measurements of visual acuity. The greater binocular sensitivity in the low frequency range (0.04 c/deg) could be tentatively attributed to the greater influence of the population of large ganglion cells that reaches its maximal density in the ipsilateral projection.

Animals↗
PubMed1992

Anxiolytic-like effects of alpha-2-adrenoceptor agonists on conflict behavior in the rat: pre- versus postsynaptic receptor mechanisms.

The effects of acute pretest administration and chronic posttest administration of clonidine or the selective alpha 2-adrenoceptor agonist UK-14,304 on conflict behavior were investigated. In daily 10-min sessions, water-deprived rats were trained to drink water from a tube that was occasionally electrified (0.25 mA); electrification was signaled by a tone. Prior to treatment, subjects accepted 25-30 shocks/session (punished responding) and consumed approximately 12-15 ml/session (unpunished responding). Acute pretest administration of clonidine or UK-14,304 did not increase punished responding. In contrast, chronic posttest clonidine administration (40 micrograms/kg, IP, twice daily for 8 weeks) resulted in a robust and time-dependent increase in punished responding (60-70 shocks/session) relative to saline-treated controls. Moreover, the selective alpha 2-adrenoceptor agonist UK-14,304 also increased punished responding when administered chronically (1.0 mg/kg, BID). Administration of the noradrenergic neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine HCl (DSP4, 65 mg/kg, IP) significantly decreased punished responding in control conditioned suppression of drinking sessions. The anticonflict effect associated with chronic posttest clonidine treatment was not altered by DSP4 pretreatment. These findings suggest that chronic posttest alpha 2-adrenoceptor agonist treatment produces an anticonflict effect independent of its actions at presynaptic alpha 2-adrenoceptors.

Adrenergic alpha-Agonists↗
PubMed2004

The effect of off-the-visual-axis retinoscopy on objective refractive measurement.

PURPOSE: To determine the effect of off-axis retinoscopy on objective refractive measurement. DESIGN: Prospective experimental study. METHODS: Eight volunteers underwent cycloplegic retinoscopy of their right eye on-the-visual-axis, and 5, 10, 15, and 20 degrees off-the-visual-axis in adduction. A single masked examiner performed all retinoscopy with random order of the patient and axis refracted. RESULTS: The average spherical retinoscopic value at 0, 5,10,15, and 20 degrees of off-axis alignment was -0.40, -0.90, -1.00, -1.38, and -1.80 diopters, respectively. The average spherical equivalent retinoscopic value obtained for each of the above positions of eye alignment was -0.02, -0.59, -0.45, -0.64, and -0.98 diopters, respectively. The induced cylinder power increased by an average of 3% for each degree of off-axis retinoscopy, though the axis of the cylinder was not predictable. CONCLUSION: Objective refractive measurement by retinoscopy is significantly altered by off-the visual-axis retinoscopy. The induced error may be clinically important even with small degrees of eccentricity.

Adult↗
PubMed2005

Screening for diabetic retinopathy by ophthalmologists and endocrinologists with pupillary dilation and a nonmydriatic digital camera.

PURPOSE: To assess the effects of pupillary dilation on image quality and certitude of screening diabetic retinopathy by trained endocrinologists using a digital nonmydriatic camera. DESIGN: Prospective, comparative, observational case series. METHODS: One hundred fifty patients with diabetes attending a hospital-based photographic screening clinic had five-field (45 degree) digital retinal imaging and mosaic construction, first through dark-adapted pupils, then after a single application of tropicamide 1%. The 600 sets of images (150 patients, 300 eyes, before and after dilation) were graded independently and in a blinded manner by two endocrinologists and two ophthalmologists, with the consensual opinion on dilated images of the latter serving as the gold standard. The criteria of evaluation were assessment of image quality and certitude of detecting and grading retinopathy. RESULTS: Of 300 eyes, pharmacological mydriasis improved image quality, with an increase in the number of eyes with five good images from seven to 160 and good-quality mosaics from 99 to 233. Dilation allowed better identification of maculopathy in the second eye because there was a decrease in ungradeable central images from 127 to 15 eyes. Dilation increased the number of eyes having retinopathy detected with certainty from 153 to 252 and graded with certainty from 173 to 277. No adverse effects were recorded. CONCLUSIONS: Single application of tropicamide 1% significantly improves image quality and certitude of screening diabetic retinopathy with nonmydriatic camera by endocrinologists.

Adolescent↗
PubMed2006

Higher-order aberrations in children.

PURPOSE: To quantify and characterize higher order aberrations in children and to investigate the influence of refractive error and cycloplegia. DESIGN: Observational cross-sectional study. METHODS: setting: Clinical practice. patients: One hundred sixty-two eyes of 82 children were examined. The mean age of the children was 6.7 years (range, 4 to 14 years), and the mean manifest refractive spherical equivalent was 2.39 +/- 3.35 diopters (range, -8.98 to +8.45 diopters). Aberrometry was performed with a wavefront analyzer (after cycloplegia and mydriasis with cyclopentolate 1%). Aberrometry was also conducted on a subgroup of 52 eyes of 27 children, both before and 30 minutes after the instillation of cyclopentolate 1% to investigate the effect of paralysis of accommodation. RESULTS: Mean root mean square values of total-, third-, fourth-, and fifth-order aberrations were 0.37 +/- 0.13 microm, 0.23 +/- 0.12 microm, 0.16 +/- 0.11 microm, and 0.08 +/- 0.12 microm, respectively. Mean root mean square values of total coma (Z(3)(-1), Z(3)(1), Z(5)(-1), Z(5)(1)) and total trefoil (Z(3)(-3), Z(3)(3), Z(5)(-3), Z(5)(3)) were 0.27 +/- 0.31 microm and 0.21 +/- 0.29 microm, respectively. Myopes had statistically significant greater levels of total (P = .005) and fourth order (P = .002) aberrations and Zernicke terms (Z(3)(-3), Z(3)(-1), Z(3)(3), Z(4)(-4), and Z(4)(2)) compared with hyperopes. Cycloplegia had minimal influence on higher-order aberrations. CONCLUSION: Significant levels of higher-order aberrations were found in these children. They were influenced by refractive error, because myopes had significantly greater levels compared with hyperopes. Paralysis of accommodation with cyclopentolate appeared to have little effect on higher-order aberrations.

Accommodation, Ocular↗