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PubMed2002

Cyclodextrins in eye drop formulations: enhanced topical delivery of corticosteroids to the eye.

Cyclodextrins are cylindrical oligosaccharides with a lipophilic central cavity and hydrophilic outer surface. They can form water-soluble complexes with lipophilic drugs, which 'hide' in the cavity. Cyclodextrins can be used to form aqueous eye drop solutions with lipophilic drugs, such as steroids and some carbonic anhydrase inhibitors. The cyclodextrins increase the water solubility of the drug, enhance drug absorption into the eye, improve aqueous stability and reduce local irritation. Cyclodextrins are useful excipients in eye drop formulations of various drugs, including steroids of any kind, carbonic anhydrase inhibitors, pilocarpine, cyclosporins, etc. Their use in ophthalmology has already begun and is likely to expand the selection of drugs available as eye drops. In this paper we review the properties of cyclodextrins and their application in eye drop formulations, of which their use in the formulation of dexamethasone eye drops is an example. Cyclodextrins have been used to formulate eye drops containing corticosteroids, such as dexamethasone, with levels of concentration and ocular absorption which, according to human and animal studies, are many times those seen with presently available formulations. Cyclodextrin-based dexamethasone eye drops are well tolerated in the eye and seem to provide a higher degree of bioavailability and clinical efficiency than the steroid eye drop formulations presently available. Such formulations offer the possibility of once per day application of corticosteroid eye drops after eye surgery, and more intensive topical steroid treatment in severe inflammation. While cyclodextrins have been known for more than a century, their use in ophthalmology is just starting. Cyclodextrins are useful excipients in eye drop formulations for a variety of lipophilic drugs. They will facilitate eye drop formulations for drugs that otherwise might not be available for topical use, while improving absorption and stability and decreasing local irritation.

Administration, Topical↗
PubMedDate not supplied

Conservation of the expression of Dll, en, and wg in the eye-antennal imaginal disc of stalk-eyed flies.

We studied the developmental basis of exaggerated eye span in two species of stalk-eyed flies (Cyrtodiopsis dalmanni and Sphyracephala beccarn). These flies have eyes laterally displaced at the end of eyestalks, and males have greatly exaggerated eye span, which they use as a sexual display. To investigate eye span development we have compared eye-antennal disc morphology and the expression of three key regulator genes of Drosophila head development, Distal-less (Dll), engrailed (en), and wingless (wg), in the stalk-eyed flies and Drosophila. We found great similarity in the basic division of the disc into anterior-antennal and posterior-eye portions and in the general patterning of Dll, en, and wg. Unexpectedly, our results showed that although the eye and antenna are adjacent in adult stalk-eyed flies, their primordia are physically separated by the presence of an intervening region between the anterior and posterior portions of the disc. This region is absent from Drosophila eye-antennal discs. We chose two stalk-eyed fly species that differed in the degree of eye-stalk exaggeration but surprisingly we found no corresponding difference in the size of the en-wg expression domains that mark the boundaries of the dorsal head capsule primordia. In summary, our expression data establish the regional identity of the eye-antennal disc and provide a framework from which to address the developmental genetics of hypercephaly.

Animals↗
PubMed1991

Effects of 9-(1,3-dihydroxy-2-propoxymethyl) guanine (DHPG) eye drops and cyclosporine eye drops in the treatment of herpetic stromal keratitis in rabbits.

The effect of 9-(1,3-dihydroxy-2-propoxymethyl) guanine (ganciclovir, DHPG) eye drops and the anti-inflammatory effect of cyclosporine (CYA) eye drops on experimental herpetic stromal keratitis in rabbits with herpes simplex virus (HSV) were studied. Ten rabbits were presensitized by subcutaneous injection of HSV, type 1, on days 14 and 7 before intrastromal inoculation of the same virus. These rabbits were divided into 2 groups and treatment was started 48 hours after virus inoculation. The eye drops used were 0.1% DHPG, 0.1% CYA or the vehicles of these eye drops. Eye drops were given 5 times a day and eyes were scored every day for 3 weeks after inoculation. The right eyes of Group 1 were treated with 0.1% DHPG and 0.1% CYA eye drops, and the left eyes with 0.1% DHPG and the vehicle of CYA eye drops. The right eyes of Group 2 were treated with 0.1% CYA and the vehicle of DHPG eye drops, and the left eyes with the vehicles of CYA and DHPG eye drops. The combination of DHPG and CYA was the most effective in decreasing the severity of herpetic stromal keratitis. Treatment with DHPG alone was also effective, but CYA alone was less effective.

Administration, Topical↗
PubMed1997

Appositional angle closure in eyes with narrow angles: comparison between the fellow eyes of acute angle-closure glaucoma and normotensive cases.

PURPOSE: To identify topologic features of eyes with acute primary angle-closure glaucoma before an attack as compared with those features in normotensive cases, assuming that untreated fellow eyes of acute primary angle-closure glaucoma are candidates for an acute attack. METHODS: A total of 50 eyes (12 fellow eyes of acute primary angle-closure glaucoma and 38 normotensive cases with a closure-possible narrow angle) were prospectively examined by ultrasound biomicroscopy under dark-room conditions. All eyes were examined before surgical or laser intervention and had normal pupillary reaction without any topical drugs. Four predetermined angle locations per eye were examined. Parameters regarding the chamber angle configuration were measured and compared between the two groups. RESULTS: Appositional angle closures were observed in 27 locations in fellow eyes and in 48 locations in normotensive eyes with a closure-possible narrow angle. The incidence was statistically different between the two groups (69.2% in the fellow eyes and 48% in the normotensive eyes). Appositional angle closures beginning at the entrance of the angle were more frequently detected in the fellow eye group. The distance between the iris root and the bottom of the angle was significantly different between the two groups. CONCLUSION: The fellow eyes of acute primary angle-closure glaucoma have different topologic features from normotensive narrow-angled eyes and a higher incidence of appositional closure that may predispose these eyes to an imminent acute attack.

Acute Disease↗
PubMed1994

Retinal specificity in eye fragments: investigations on the retinotectal projections of different quarter-eyes in Xenopus laevis.

According to Sperry's chemoaffinity hypothesis, the projection of a small eye fragment with a reduced amount of optic fibres should be restricted to that position in the optic tectum corresponding to its own specificity. However, previous investigations on different types of quarter-eyes in Xenopus laevis have revealed that their retinal projection was always restricted to the rostral part of the tectum, no matter what the origin of the remaining retinal quadrant. To get an indication of the state of specificity in such eye fragments, we investigated by electrophysiological and histological methods several features of the retinal projections of tempo-roventral (TV), naso-ventral (NV) and ventral (V) quarter-eyes which referred to their positional identity. Irrespective of their different origins, the projections were always located in the rostral part of the tectum, the size of the innervated tectal area depending for all fragment types on the size of the quarter-eyes, i.e. number of optic fibres. However, quantitative analyses revealed that with increasing eye size the various fragments expand their projections preferentially into those tectal areas that match their original specificity: TV projection is more concentrated in the rostral tectum, NV eyes expand their projections mainly to the caudal tectum, and V eyes enlarge their projections equally into the medial and caudal tectum. In addition, fibre-tracing experiments with cobaltic lysine showed that, according to the different origins of the quarter-eyes, retinal fibres follow the appropriate branch of the optic tract selectively: fibres of NV and V eyes pass mainly through the medial tract, and most fibres of TV eyes innervate the rostral tectum directly from a central position between the two side branches. All these findings suggest that the different types of quarter-eyes retain their original positional identity. Thus, their rostrally located retinotectal projections are not in register with their retinal specificity. We conclude that in X. laevis local positional markers in the tectum, if present at all, do not influence the development of the retinotectal projection. Instead we suggest a concept of self-sorting of the optic fibres, which can account for the partial innervation of the rostral tectum in different types of quarter-eyes.

Animals↗
PubMedDate not supplied

Binocular eye orientation during fixations: Listing's law extended to include eye vergence.

Any eye position can be reached from a position called the primary position by rotation about a single axis. Listing's law states that for targets at optical infinity all rotation axes form a plane; the so-called Listing plane. Listing's law is not valid for fixation of nearby targets. To document these deviations of Listing's law we studied binocular eye positions during fixations of point targets in the dark. We tested both symmetric (targets in a sagittal plane) and asymmetric vergence conditions. For upward fixation both eyes showed intorsion relative to the position that would have been taken if each eye followed Listing's law. For downward fixation we found extorsion. The in- or extorsion increased approximately linearly with the vergence angle. The direction of the Listing axis and the turn angle about this axis can be described by rotation vectors. Our observations indicate that for fixation of nearby targets the rotation vectors of the two eyes become different and are no longer located in a single plane. However, we find that it is possible to decomose the rotation vector of each eye into the sum of a symmetric and an anti-symmetric part, each with its own properties. (1) The symmetric part is associated with eye version. This component of the rotation vector is identical for both eyes and lies in Listing's plane. In contrast to the classical form of Listing's law, this part of the rotation vector lies in Listing's plane irrespective of the fixation distance. (2) The anti-symmetric part of the rotation vector is related to eye vergence. This component is of equal magnitude but oppositely directed in each eye. The anti-symmetric part lies in the mid-sagittal plane, also irrespective of fixation distance. For fixation of targets at optical infinity the anti-symmetric part equals zero and the eye positions obey the classical form of Listing's law. Thus, the symmetric and anti-symmetric parts of the rotation vectors are restricted to two perpendicular planes. Combining these restrictions in a model, with the additional restriction that the vertical vergence equals zero during fixation of point targets, we arrive at the prediction that the cyclovergence is proportional to the product of elevation and horizontal vergence angles. This was well born out by the data. The model allows to describe the binocular eye position for fixation of any target position in terms of the bipolar coordinates of the target only (i.e. using only three degrees of freedom instead of the six needed for two eyes).

Eye Movements↗
PubMed2004

Relative image size, not eye position, determines eye dominance switches.

A recent paper examined eye dominance with the eyes in forward and eccentric gaze [Vision Res. 41 (2001) 1743]. When observers were looking to the left, the left eye tended to dominate and when they were looking to the right, the right eye tended to dominate. The authors attributed the switch in eye dominance to extra-retinal signals associated with horizontal eye position. However, when one looks at a near object on the left, the image in the left eye is larger than the one in the right eye, and when one looks to the right, the opposite occurs. Thus, relative image size could also trigger switches in eye dominance. We used a cue-conflict paradigm to determine whether eye position or relative image size is the determinant of eye-dominance switches with changes in gaze angle. When eye position and relative image size were varied independently, there was no consistent effect of eye position. Relative image size appears to be the sole determinant of the switch.

Cues↗
PubMed2006

PP2A:B56epsilon is required for eye induction and eye field separation.

Eye induction and eye field separation are the earliest events during vertebrate eye development. Both of these processes occur much earlier than the formation of optic vesicles. The insulin-like growth factor (IGF) pathway appears to be essential for eye induction, yet it remains unclear how IGF downstream pathways are involved in eye induction. As a consequence of eye induction, a single eye anlage is specified in the anterior neural plate. Subsequently, this single eye anlage is divided into two symmetric eye fields in response to Sonic Hedgehog (Shh) secreted from the prechordal mesoderm. Here, we report that B56epsilon regulatory subunit of protein phosphatase 2A (PP2A) is involved in Xenopus eye induction and subsequent eye field separation. We provide evidence that B56epsilon is required for the IGF/PI3K/Akt pathway and that interfering with the PI3K/Akt pathway inhibits eye induction. In addition, we show that B56epsilon regulates the Hedgehog (Hh) pathway during eye field separation. Thus, B56epsilon is involved in multiple signaling pathways and plays critical roles during early development.

Animals↗
PubMed1995

Altered vasoactivity in the early diabetic eye: measured in the isolated perfused rat eye.

The effect of 4 weeks streptozotocin-induced diabetes on ocular vascular resistance responses to noradrenalin (NA), adrenalin (A), phenylephrine (PHE), isoproterenol (ISOP), prostaglandin F2 alpha (PGF2 alpha). 5-hydroxytryptamine (5-HT) and angiotensin II (ANG II), was determined using a newly-developed, isolated, arterially-perfused rat eye preparation, by comparing responses from control and diabetic eyes. After extensive preliminary experiments to establish optimum parameters, the ophthalmic artery of enucleated control and diabetic rat eyes was cannulated and the retinal and uveal vasculature perfused at a constant flow with Na(+)-Krebs solution after streptozotocin-induced diabetes had been established for 4 weeks. The eyes were maintained in an environment-controlled organ bath. Perfusion pressure was monitored as increasing log M concentrations of agonists were added to the perfusate. Total ocular resistance could be calculated from knowledge of flow and pressure. In control eyes, NA, A, PHE, PGF2 alpha, and 5-HT all produced dose-dependent increases in total vascular resistance, with the following order of potency: NA = A > 5-HT > PHE = PGF2 alpha at 10(-4) M. The ocular circulation was not sensitive to isoproterenol and angiotensin II. In diabetic eyes responses to NA, A, PGF2 alpha and 5-HT were altered. Diabetic responses to NA and A had lower thresholds with larger resistance increases at low concentrations. However, the rate of increase in resistance with concentration was more gradual in diabetic eyes so that at 10(-4) M control responses were larger. Diabetic resistance responses to PGF2 alpha had the same threshold as in control eyes, but were greater in magnitude with an earlier peak at 10(-4) M. In contrast diabetic resistance responses to 5-HT were reduced, peaked at a lower resistance at 10(-4) M, but had the same threshold as those in the control eye. Basal vascular resistances in control: 3.14 +/- 0.32 mmHg min microliter-1 (n = 28), and diabetic eyes: 3.44 +/- 0.19, mmHg min microliter-1 (n = 36), were not significantly different. Vasoactivity in the early diabetic eye is disturbed with the effective balance between different agonists altered in favour of catecholamines at physiological concentrations. This may be related to the early changes in blood flow and oxygen distribution already reported in the rat eye, as well as changes to autonomic function. The isolated perfused rat eye is a valuable technique for investigating such vascular reactivity in animal models of retinal disease.

Angiotensin II↗
PubMed2003

Prevalence of dry eye among an elderly Chinese population in Taiwan: the Shihpai Eye Study.

PURPOSE: To describe the epidemiology of dry eye in an elderly Chinese population in Taipei, Taiwan. DESIGN: A population-based cross-sectional study. PARTICIPANTS: The Shihpai Eye Study was a population-based survey of eye diseases in the elderly (> or =65 years) in Shihpai, Taipei, Taiwan. Noninstitutionalized residents, as of July 1999, were identified by using the official household registration database. A total of 2045 subjects were selected, and 1361 (66.6%) people participated in the study. Among them, 822 (60.4%) were men. METHODS: Trained interviewers administered a standardized questionnaire pertaining to dry-eye symptoms. Objective examinations of dry eye included tear film breakup time, Schirmer test, fluorescein stain of the cornea, and anatomic assessment of the meibomian glands via slit-lamp biomicroscopy. MAIN OUTCOME MEASURES: Frequency of dry-eye symptoms and positive dry-eye tests. RESULTS: In this population, 33.7% (459/1361) were symptomatic, defined as reporting 1 or more dry-eye symptoms often or all of the time. Women were more likely to report frequent symptoms of dry eye (odds ratio, 1.49; 95% confidence interval, 1.19-1.87). Among those who were symptomatic, 78.9% (362/459) had a low tear film breakup time (< or =10 seconds), 62.5% (287/459) had a low Schirmer test result (< or =5 mm), and 61.7% (283/459) had abnormal anatomic features of the meibomian glands. Furthermore, 85.4% (392/459) were symptomatic and had either a low Schirmer score or an abnormal meibomian gland assessment. Of those symptomatic, 49.9% (229/459) indicated that they had visited an eye doctor, 5.4% (25/459) responded that they had been diagnosed with dry eye, and 47.5% (218/459) reported current use of eyedrops. CONCLUSIONS: This is the first report of population-based data of dry eye that includes symptoms and signs in elderly Asians. The prevalence of dry eye, although varied according to definition, is relatively higher in this study than that reported for whites. Further studies are needed to determine whether this is due to racial or environmental factors.

Age Distribution↗
PubMed2001

Phylogenetic analysis of sexual dimorphism and eye-span allometry in stalk-eyed flies (Diopsidae).

Eye stalks and their scaling relationship with body size are important features in the mating system of many diopsid species, and sexual selection is a critical force influencing the evolution of this exaggerated morphology. Interspecific variation in eye span suggests there has been significant evolutionary change in this trait, but a robust phylogenetic hypothesis is required to determine its rate and direction of change. In this study, the pattern of morphological evolution of eye span is assessed in a phylogenetic framework with respect to its function in the sexual system of these flies. Specifically, we examine within the family Diopsidae the pattern of increase and decrease in sexual dimorphism, the morphological coevolution of eye span between males and females, and the evolutionary flexibility of eye-span allometry. Based on several different methods for reconstructing morphological change, results suggest a general pattern of evolutionary flexibility, particularly for eye-span allometry. Sexual dimorphism in eye span has evolved independently at least four times in the family and this trait also has undergone several reductions within the genus Diasemopsis. Despite most species being dimorphic, there is a strong phylogenetic correlation between males and females for mean eye span. The coevolution between the sexes for eye-span allometry, however, is significantly weaker. Overall, eye-span allometry exhibits significantly more change on the phylogeny than the other morphological traits. The evolutionary pattern in eye-span allometry is caused primarily by changes in eye-span variance. Therefore, this pattern is consistent with recent models that predict a strong relationship between sexual selection and the variance of ornamental traits and highlights the significance of eye-span allometry in intersexual and intrasexual signaling.

Animals↗
PubMed1995

Effects of eye position on saccadic eye movements and on the neuronal responses to auditory and visual stimuli in cat superior colliculus.

Many neurons in the deeper layers of the superior colliculus (SC) respond to multiple sensory inputs--visual, auditory, and somatic--as well as provide signals essential for saccadic eye movements to targets in different modalities. When the eyes and pinnae are in primary position, the neural map of auditory space is in rough topographic alignment with the map of visual space, and if the auditory map is based solely on headpinna coordinates, any changes in eye position in the orbit will cause misalignment of the maps. We investigated the effects of eye position on the response of sound-sensitive neurons in the SC of cats because previous work on cats and on monkeys had suggested the possibility of species differences in the representation of auditory signals in the SC. We also investigated the effects of eye position on the accuracy of saccades to auditory, visual, and bimodal stimuli. All studies were conducted in alert, trained cats with the head restrained in a fixed position. Neuronal and behavioral responses were studied during periods when the eyes were steadily directed to different positions relative to the position of the sound. Cats showed partial compensation for eye position in making saccades, regardless of the modality of the target, and they showed similar patterns of error in saccades to auditory and visual targets. These behavioral data are consistent with coding the location of visual and auditory targets in the same coordinate system. In the vast majority of intermediate-layer neurons, eye position significantly affected the number of spikes evoked by sound stimuli. For most of these neurons, changes in eye position produced significant shifts in the speaker location producing maximal response. In some neurons, eye position significantly facilitated the magnitude of neuronal response evoked by sounds from a variety of speaker locations. Because few pinna movements could be detected, in is unlikely that these changes in neuronal response could be due to changes in the position of the pinnae. Our results indicate that the deep layers of the SC contain an eye-centered representation of sound location. Because eye position did not affect the percentage of neurons exhibiting multimodal integration, visual and auditory maps appear to remain integrated in the SC even when the eyes are directed eccentrically.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMedDate not supplied

Reliability of the first eye and second eye in frequency doubling technology perimetry.

PURPOSE: To compare the reliability of the perimetry results of the first eye and the second eye with frequency doubling technology (FDT). METHODS: The subjects were 328 residents who underwent the C-20-5 mode of FDT at a city in central Japan. FDT perimetry was always performed first in the right eye and then in the left eye without any time between tests. When more than 33% fixation loss or false-positive error was detected, the result was judged unreliable. RESULTS: Of the 328 subjects, the bilateral perimetry results were reliable in 255 subjects (77.7%), the unilateral results were reliable in 57 (17.4%), and there was not a reliable result in either eye in 16 (4.9%) subjects. Of the 57 subjects whose unilateral result was unreliable, the result of the second eye was unreliable in 50 (88%) subjects, and the result of the first eye was unreliable in 7 (12%). This difference in the reliability between the first eye and second eye was significant (P < 0.001). There were no differences in the age, sex, visual acuity, refractive error, test duration, or number of glaucoma suspects between the two groups whose unilateral result was unreliable in the first eye or the second eye. CONCLUSIONS: The FDT perimetry result of the second eye was less reliable than that of the first eye.

Adult↗
PubMed2005

Variation of 24-hour intraocular pressure in healthy individuals: right eye versus left eye.

PURPOSE: An assumption for the one-eye therapeutic trial of ocular hypotensive drugs is the symmetrical variation of intraocular pressure (IOP) between the two eyes. We evaluated whether or not 24-hour variations of IOP in the two eyes are similar in healthy individuals. DESIGN: Experimental study with human subjects. PARTICIPANTS: Ninety-one healthy individuals. METHODS: We reviewed bilateral IOP data collected from 38 younger (18-25 years) and 53 older (40-74 years) experimental subjects housed for 24 hours in a sleep laboratory. Intraocular pressure was measured every 2 hours using a pneumatonometer in the sitting and supine positions during the 16-hour diurnal/wake period and in the supine position during the 8-hour nocturnal/sleep period. Measurements were always taken first in the right eye. For each age group, the two eyes' means, peaks, troughs, and ranges of IOP during office hours, the diurnal period, the nocturnal period, and the 24-hour period were compared. The coefficient of determination was used to examine the strength of association between the right and left IOPs. MAIN OUTCOME MEASURES: Bilateral IOP. RESULTS: For each age group, the profiles of IOP variations were similar in the two eyes with either the habitual body positions (diurnal sitting and nocturnal supine) or the 24-hour supine position. Mean, peak, and trough IOPs in the right eye were slightly higher than those in the left eye during the defined periods. There was no difference in the IOP range, except for the supine IOP in the younger group during the diurnal period. Cosine fits of the 24-hour supine IOP indicate no difference in the estimated phase timing or the 24-hour variation between the two eyes. Coefficients of determination for single pairs of right and left IOPs were in the range of 0.311 to 0.741. CONCLUSION: Variations of 24-hour IOP in the right and left eyes are similar. However, because the strength of association between the two eyes is only moderate, it may be difficult to perform a one-eye therapeutic trial using single pairs of right and left eye IOP measurements.

Adolescent↗
PubMed2005

Deep sclerectomy in one eye vs deep sclerectomy with collagen implant in the contralateral eye of the same patient: long-term follow-up.

PURPOSE: To compare prospectively the results of deep sclerectomy (DS) vs deep sclerectomy with collagen implant (DSCI). METHODS: Randomized prospective trial involving 26 eyes (13 patients) with medically uncontrolled primary and secondary open angle glaucoma. Collagen implant was randomly assigned to one eye of each patient. RESULTS: The mean follow-up period was 49.5 (SD 20) months for the DS-treated eyes, and 56.5 (SD 14) months for the DSCI-treated eyes (P=0.4). The mean preoperative intraocular pressure (IOP) was 24.1 (SD 7) mmHg for the DS-treated eyes, and 25.3 (SD 6) mmHg for the DSCI-treated eyes (P=0.5). The mean IOP at the first postoperative day was 6.4 (SD 3) mmHg for the DS-treated eyes, and 3.7 (SD 2) mmHg for the DSCI-treated eyes (P=0.05). The mean IOP at 12 months postoperative day was 15.4 (SD 3) mmHg for the DS group, and 10.4 (SD 4) mmHg for the DSCI-treated eyes (P=0.04), while at 48 months it was 16 (SD 3) mmHg for the DS group, and 10 (SD 4) mmHg for the DSCI-treated eyes (P=0.005). Complete success rate, defined as an IOP lower than 21 mmHg without medication, was 38% (5/13 patients) at 48 months for the DS-treated eyes, and 69% (9/13 patients) for the DSCI-treated eyes. Qualified success rate: patients who achieved IOP below 21 mmHg with or without medication, was 69% (9/13 patients) at 48 months and 100% (13/13 patients) for the DSCI group. The mean number of medications was reduced from 2.4 (SD 0.8) to 1.1 (SD 1) after DS, and was reduced from 2.2 (SD 0.7) to 0.4 (SD 0.6) in the DSCI group (P=0.001). For those eyes treated with DSCI, IOP was 3.21 mmHg lower than for those treated with DS (P<0.0001). CONCLUSION: The use of a collagen implant in DS seems to enhance the success rates, provides significantly lower IOP levels, and lowers the need for postoperative medications.

Aged↗
PubMed2003

Spectral sensitivity in eyes with macular holes and their fellow eyes.

BACKGROUND: This prospective study was undertaken to investigate whether spectral sensitivity can be useful in determining the prognosis of fellow eyes of eyes with macular holes. METHODS: Spectral sensitivity measurements using a one degree test spot presented at a rate of 1 Hz and 25 Hz on a bright (1000 td) white background were carried out on 10 patients aged between 67 and 74 years (mean age 70.3 +/- 2.6 years). Each patient had a full thickness macular hole in one eye and a normal contralateral fellow eye. The spectral sensitivity measurements were made with eccentric fixation in the eyes with macular holes and with central fixation in the normal fellow eye. A year later, the patient files were reviewed to look at the patient's ocular condition. Another 10 subjects between the ages of 50 and 80 years (mean age 69.5 +/- 4.2 years) were also seen. These control group subjects had visual acuities of 6/9 or better with minimal ocular media changes and no ocular or systemic pathology that could affect colour vision. RESULTS: The 1 Hz and 25 Hz spectral sensitivities of all patients were reduced for both eyes. Despite the good eye without a macular hole having a VA of 6/6, the spectral sensitivity was similar to that of the eye with the macular hole and markedly reduced visual acuity. CONCLUSION: The present investigation enabled us to examine the chromatic and achromatic mechanisms by testing spectral sensitivity at 1 Hz and 25 Hz, respectively. The data revealed that both chromatic and achromatic processing could be damaged in the eye with a macular hole. Surprisingly, the spectral sensitivities of both 1 Hz and 25 Hz are equally reduced in the good fellow eye with no macular hole. A one-year follow-up showed that two of the 10 patients (20 per cent) did eventually develop a macular hole in the normal fellow eye. This indicates that there is some subclinical foveal dysfunction in the normal fellow eye, the nature of which is unclear.

Aged↗
PubMed1996

Functionally defined smooth and saccadic eye movement subregions in the frontal eye field of Cebus monkeys.

1. Intracortical microstimulation was used to localize and define the smooth and saccadic eye movement subregions of the frontal eye field (FEF) and the supplementary eye field (SEF) in nine hemispheres of six Cebus apella monkeys and to map the hand/arm areas in the dorsal premotor area and other adjacent areas in five hemispheres of three C. apella monkeys. Monkeys were anesthetized during experiments with Telazol, a dissociative agent that has no significant effect on microstimulation-induced eye movement parameters (current threshold, velocity, and duration). The functional subregions were defined with the use of low threshold current (< or = 50 microA). Electrically elicited eye movements were videotaped and quantified. The two types of eye movements were clearly distinguished by their significantly different duration and velocity (P < 0.0001) and their different responses to long stimulus trains. 2. The saccadic subregion of the FEF in Cebus monkeys is in the same location as in macaque monkeys (Walker's areas 8a and 45). Most of the functional and anatomic characteristics of the saccadic subregion of Cebus are the same as those reported in the saccadic FEF subregion of macaque monkeys. 3. A subregion in which only smooth eye movements were evoked was found in the posterior shoulder of the superior arcuate sulcus near its medial tip. A band of inexcitable cortex separated the SEF and this smooth eye movement subregion of the FEF. This supports the proposal that the smooth eye movement subregion is independent of the SEF but is analogous to the saccadic subregion of the FEF. The existence of two subregions of the FEF was further confirmed by single-unit recording results. It is proposed that the smooth eye movement subregion in Cebus monkeys may be comparable with the one described in macaque monkeys. 4. Both saccadic and smooth eye movements were also reliably evoked in the SEF in each hemisphere studied. This result strongly indicates that the SEF is concerned with not only saccadic eye movements, as previously reported, but also with smooth (pursuit) eye movements.

Animals↗