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At least 271 records · Page 15Linked to original sources
PubMed2006

Effects of ablation diameter on long-term refractive stability and corneal transparency after photorefractive keratectomy.

OBJECTIVE: To evaluate the effects of ablation diameter on long-term refractive stability and corneal transparency after photorefractive keratectomy (PRK). DESIGN: Long-term, prospective, follow-up study. PARTICIPANTS: One hundred twenty-three eyes treated between 1990 and 1993 at one institution as part of a number of ethical committee-approved clinical studies underwent long-term follow-up at 10 to 12 years after PRK. INTERVENTION: Photorefractive keratectomy was performed using the Summit Technology UV 200 and OmniMed Excimer lasers with either 4.0-mm (n = 36), 5.0-mm (n = 47), or 6.0-mm (n = 40) optical zones and either -3.0-diopters (D) or -6.0-D myopic spherical corrections, based on the original Munnerlyn algorithms. MAIN OUTCOME MEASURES: Refractive stability, refractive predictability, best spectacle-corrected visual acuity, and corneal haze. RESULTS: Refractive outcome at 1 and 10 to 12 years of follow-up was better with 6.0-mm treatments, especially for -6.0-D corrections (P>0.001). The early hyperopic shift was significantly reduced with 6.0-mm zones, with less regression between 1 and 6 months, compared with 5.0- and 4.00-mm PRK, especially for -6.0-D corrections (P<0.001). The postoperative refraction remained stable between 1 and 10 to 12 years in all groups. Objective measurements of haze were less with 6.0-mm compared with 4.0- and 5.0-mm treatments (P<0.001). Night vision problems were significantly less with 6.0-mm PRK (P<0.01). There was no evidence of progressive hyperopic shift, corneal ectasia, or late onset of corneal haze in any of the eyes during the follow-up period. CONCLUSIONS: Refractive stability was maintained between 1 year and 10 to 12 years after PRK with 4.0-, 5.0-, and 6.0-mm optical zones. A significant linear trend was observed in terms of refractive predictability, early hyperopic shift, regression, corneal transparency, and night haloes with better outcomes in PRK with a larger ablation zone. None of the eyes had sight-threatening complications such as ectasia or late-onset corneal haze during the follow-up.

Cornea↗
PubMed1993

Symptomatic abnormalities of dark adaptation in patients with age-related Bruch's membrane change.

Some patients with age-related changes at the level of Bruch's membrane and good visual acuity report poor vision in dim light, fading vision in bright light, and a central scotoma noticeable in the dark. Ophthalmic examination, scotopic thresholds, and dark adaptation kinetics were recorded in 12 eyes of 12 patients with such symptoms. All had macular drusen which were hypofluorescent on fluorescein angiography in nine subjects, and six had evidence of prolonged choroidal filling on fluorescein angiography. Scotopic thresholds were depressed in six patients who all experienced a central scotoma in the dark or poor night vision. The kinetics of dark adaptation were abnormal in all 10 patients in whom reliable measurements were possible. The findings suggest that visual symptoms reflect abnormality of both scotopic sensitivity and the time course of dark adaptation in patients with age-related Bruch's membrane change.

Aged↗
PubMed1983

Sectorial pigmentary retinopathy associated with head trauma.

Retinal lesions resembling retinitis pigmentosa were observed in a 39-year-old white male patient with a history of head trauma, reduced night vision, and periodic perception of light flashes. Perimetric testing revealed contracted superior-temporal fields. The results of numerous other tests of visual function, however, failed to support the tentative funduscopic diagnosis of sector retinitis pigmentosa.

Adult↗
PubMed2006

Night firing range performance following photorefractive keratectomy and laser in situ keratomileusis.

OBJECTIVE: To investigate the effect of laser refractive surgery on night weapons firing. METHODS: Firing range performance was measured at baseline and postoperatively following photorefractive keratectomy and laser in situ keratomileusis. Subjects fired the M-16A2 rifle with night vision goggles (NVG) at starlight, and with iron sight (simulated dusk). Scores, before and after surgery, were compared for both conditions. RESULTS: No subject was able to acquire the target using iron sight without correction before surgery. After surgery, the scores without correction (95.9 +/- 4.7) matched the preoperative scores with correction (94.3 +/- 4.0; p = 0.324). Uncorrected NVG scores after surgery (96.4 +/- 3.1) exceeded the corrected scores before surgery (91.4 +/- 10.2), but this trend was not statistically significant (p = 0.063). CONCLUSION: Night weapon firing with both the iron sight and the NVG sight improved after surgery. This study supports the operational benefits of refractive surgery in the military.

Adult↗
PubMed1995

Localization of a novel X-linked congenital stationary night blindness locus: close linkage to the RP3 type retinitis pigmentosa gene region.

X-linked congenital stationary night blindness (CSNBX) is a non-progressive retinal disorder characterized by decreased visual acuity and loss of night vision. CSNBX is clinically heterogeneous with respect to the involvement of retinal rods and/or cones in the disease. In this study, we localize a new locus for CSNBX to Xp21.1, thus providing evidence that CSNBX is also genetically heterogeneous. A clear correlation between different genotypes and phenotypes cannot be found yet. The new CSNBX gene described here is closely linked to the X-linked retinitis pigmentosa type 3 gene region, which supports the hypothesis that there may be a functional relationship between congenital stationary night blindness and retinitis pigmentosa.

Chromosome Mapping↗
PubMed2005

Investigation of the performance of the Menifocal Z gas-permeable bifocal contact lens during continuous wear.

PURPOSE: The Menifocal Z is an alternating vision, concentric, bifocal gas-permeable (GP) contact lens; center distance is connected to near periphery by a smooth transition zone. The lens is produced using tisilfocon A (Menicon Z material), which is approved for up to 30 days of continuous wear (CW). The aim of this study was to evaluate the clinical performance of the Menifocal Z when worn for up to 30 days of CW for 6 months. METHODS: Thirty-five existing GP lens wearers were enrolled in the study. Subjects were fitted with Menifocal Z lenses and follow-up visits were conducted after 2 weeks of daily wear and 1 day, 1 week, 6 weeks, 3 and 6 months of CW. A range of objective and subjective clinical performance measures were assessed, including distance and near visual acuity, the physiological response to CW, and subjective evaluation of vision and comfort. RESULTS: Twenty-seven subjects (77%) completed the study and eight (23%) discontinued: five (14%) as a result of lens-related problems (four vision, one comfort) and three (9%) as a result of non-lens related reasons. Average CW time achieved by the subjects was 22 +/- 2 days. Mean binocular logarithm of the minimum angle of resolution (logMAR) acuities at 6 months were: high contrast distance 0.03 (20/20-), low contrast distance 0.63 (20/80-), and high contrast near 0.26 (20/25, N4). Adverse responses and lens binding were minimal, and there were no significant increases in corneal staining, corneal vascularization, or superior palpebral conjunctival papillae over time (p > 0.05). Problems with night vision (distance and near) with the lenses were the most common difficulties reported by the subjects. CONCLUSIONS: The Menifocal Z appears to be a promising option for presbyopic vision correction, providing successful correction of distance and near vision in a group of experienced GP lens wearers. The hyper Dk tisilfocon A (Menicon Z) material allowed for safe wear of the lenses on a CW basis.

Adult↗
PubMed1976

Retinitis pigmentosa without pigment.

Sixty-eight consecutive patients with retinitis pigmentosa were studied to determine the frequency of the nonpigmented form of the disease. There was an overall incidence of 22%. Fifty percent of all cases had no characteristic pigmentation, if the duration of night vision difficulty was three years or less. The nonpigmented form of retinitis pigmentosa was frequently an early stage of the disease and not an unusual or atypical variant. Patients without the pigmentary changes characteristic of the disorder also showed less functional impairment: the electroretinographic b wave was more apt to be recordable, although impaired, and the rod threshold, as determined by dark adaptation measurement, was less elevated. The clinician should suspect retinitis pigmentosa, even in the absence of pigmentary changes, if there is a family history of the disorder, night blindness, peripheral field loss, and an impaired or nonrecordable electroretinographic response.

Electroretinography↗
PubMed1996

Enlargement of the photorefractive keratectomy optical zone.

PURPOSE: To evaluate the safety and efficacy of a photorefractive keratectomy (PRK) re-treatment procedure that enlarges the optical zone and treats undercorrection. SETTING: Rotterdam Eye Hospital and Medisch Centrum Alkmaar, The Netherlands. METHODS: This study evaluated 16 eyes that had PRK for myopia with the Summit excimer laser that resulted in a mean undercorrection of -2.82 diopters (D). Patients also reported impaired night vision including difficulty in driving, halos, and stray light and ghost images. These phenomena persisted after spectacle correction of residual refractive error, necessitating further treatment with a larger ablation zone. With a VISX 20/20 excimer laser, the optical zone was enlarged to 6.0 mm and undercorrection treated with a 6.0 mm ablation. RESULTS: At 13.5 months after re-treatment, mean reduction in myopia was 1.70 D, resulting in a residual undercorrection of -1.08 D. In seven eyes, final refraction was within 1.00 D of emmetropia. Only two patients continued to report night-driving problems. CONCLUSIONS: Re-treating undercorrections combined with enlarging the ablation zone resulted in a reduction in myopia from a mean of 2.82 to 1.08 D. Subjective reports of halos and stray light images were decreased in all cases.

Adult↗
PubMed1999

Night blindness precipitated by isotretinoin in the setting of hypovitaminosis A.

A 16-year-old male developed night blindness 2 weeks after starting isotretinoin at a dose of 20 mg per day for cystic acne. He also had cystic fibrosis, complicated by hepatic cirrhosis. Despite long-term oral vitamin A supplementation, serum vitamin A levels were found to be 0.3 mumol/L (normal range 0.9-2.5 mumol/L). Oral vitamin A replacement was instituted with resolution of his visual symptoms in 6 months. Isotretinoin therapy was successfully continued with no deterioration in liver function. Isotretinoin has been reported to cause deterioration in night vision. In vitro evidence suggests isotretinoin may interfere with the processing of endogenous vitamin A in the retina. This case highlights the need for careful monitoring of serum vitamin A status in patients with malabsorptive states on isotretinoin therapy.

Acne Vulgaris↗
PubMed2003

Computational modeling of foveal target detection.

This paper presents the VDM2000, a computational model of target detection designed for use in military developmental test and evaluation settings. The model integrates research results from the fields of early vision, object recognition, and psychophysics. The VDM2000 is image based and provides a criterion-independent measure of target conspicuity, referred to as the vehicle metric (VM). A large data set of human responses to photographs of military vehicles in a field setting was used to validate the model. The VM adjusted by a single calibration parameter accounts for approximately 80% of the variance in the validation data. The primary application of this model is to predict detection of military targets in daylight with the unaided eye. The model also has application to target detection prediction using infrared night vision systems. The model has potential as a tool to evaluate the visual properties of more general task settings.

Calibration↗
PubMed2006

Refractive outcome after bilateral implantation of an apodized diffractive intraocular lens.

PURPOSE: Evaluation of the results of the first 30 patients, bilaterally implanted with the bifocal Acrysof Restor Apodized Diffractive intraocular lens (IOL) (SA60D3). The optics of this lens are designed to restore near and distance vision. SETTING: Department of Ophthalmology, Aalsters Stedelijk Ziekenhuis, Aalst, Belgium. METHODS: Sixty eyes of 30 patients had implantation of the Alcon Acrysof Restor SA60D3 IOL in this prospective nonrandomized clinical study. Fourty-eight eyes were evaluated at 6 months and 60 eyes at 3 months. Patient selection included no other eye disease besides cataract and corneal astigmatism of one diopter or less. Uncorrected distance visual acuity (UCVA-D), uncorrected near visual acuity (UCVAN), best corrected distance visual acuity (BCVA-D) and distance corrected near visual acuity (DCVA-N) were recorded. Glare phenomena, halos and night vision difficulties were evaluated as well as patient satisfaction. RESULTS: Postoperative UCVA-D was better than 20/ 40 at 3 months and better than 20/30 at 6 months in all eyes. UCVA-N was equal or better than Jaeger (J) 3 at 3 months in 91% and all eyes achieved J3 or better at 6 months. BCVA-D was 20/30 or better in all eyes at 3 months and 20/25 or better at 6 months. DCVA-N was J2 or better in all eyes at 3 and 6 months. Patient satisfaction was excellent (76%), good (10%) or acceptable (14%). No patient was dissatisfied with the result. Twenty percent of patients mentioned glare or halos when specifically asked. CONCLUSION: 3- and 6-month data indicate that the Acrysof Restor Apodized diffractive IOL (SA60D3) provides excellent near visual acuity without compromising distance visual acuity. The incidence of visual disturbances is low and patient satisfaction high.

Humans↗
PubMed1977

The clinical significance of retinitis pigmentosa without pigment: a computer assisted analysis.

Sixty-eight consecutive patients with retinitis pigmentosa were studied to determine the frequency of the non-pigmented form of the disease. There was an overall incidence of 22%. Fifty percent of all cases had no characteristic pigmentation, if the duration of night vision difficulty was three years or less. The study lends statistical support to the concept that the non-pigmented form of retinitis pigmentosa is frequently an early stage of the disease and not an unusual or atypical variant. Patient without the pigmentary changes characteristic of the disorder also showed less functional impairment: the ERG b-wave was more apt to be recordable, although impaired; and the rod threshold, as determined by dark adaptation measurement, was less elevated. The clinician should suspect retinitis pigmentosa, even in the absence of pigmentary changes, if there is a family history of the disorder, night blindness, peripheral field loss, and an impaired or non-recordable electroretinographic response.

Dark Adaptation↗
PubMed2004

Glare sensitivity and optical side effects 1 year after photorefractive keratectomy and laser in situ keratomileusis.

PURPOSE: To compare the outcome of low-contrast visual acuity and glare sensitivity after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). SETTING: Department of Ophthalmology, Cantonal Hospital of Lucerne, Lucerne, Switzerland. METHODS: In this prospective study, patients selected PRK or LASIK after the advantages and disadvantages of both had been described. Snellen visual acuity and disability glare were measured with the Berkeley glare test preoperatively and 1 year postoperatively. At the 1-year follow-up, haze was graded and patients had to assess their quality of vision subjectively. RESULTS: One-year follow-up of 58 patients in the PRK group and 64 patients in the LASIK group was achieved. In both groups, the mean uncorrected visual acuity was 20/32 (P =.63) and the mean best corrected visual acuity, 20/20 with no statistically significant difference (P =.20). There were no preoperative or postoperative differences between the 2 groups in low-contrast visual acuity under 4 glare conditions. At 1 year, LASIK eyes had significantly lower postoperative haze scores than PRK eyes (P =.0013). The number of eyes with visually moderate and disturbing halos or disturbances in night vision did not differ considerably between the groups (P =.88). CONCLUSIONS: Efficacy outcomes were generally similar in the PRK and LASIK groups. Both achieved good objective and subjective results after treatment with a second-generation excimer laser.

Adult↗
PubMedDate not supplied

Early retinopathy in the Bernese Mountain Dog in France: preliminary observations.

The objective of the study was to describe a form of early retinopathy in the Bernese Mountain Dog in France. Sixty-two Bernese Mountain Dogs (38 males and 24 females), whose ages ranged from 2 months to 9 years, were examined over a period of 3 years. Visual behavior, pupillary light reflexes, menace responses and ocular fundi were evaluated in all animals. Electroretinography (ERG) was performed on six of the affected dogs after dark adaptation. Fluorescein angiography (FA) was performed on one affected dog. Whenever possible, the pedigrees of the affected dogs were evaluated. A histological examination of the retina was performed on one of the affected dogs. Eight dogs (seven males and one female) were diagnosed with retinopathy with an early onset of clinical signs. (Four dogs were aged between 3 months and 1 year, two dogs were aged 2 and 3.5 years, and one dog was 7 years old.) Night vision was impaired in most of the dogs. Retinopathy was characterized ophthalmoscopically by a bilateral, symmetrical horizontal zone of tapetal hyper-reflectivity adjacent to and above the optic disc, and sometimes by peri-papillary hyper-reflectivity. ERG changes included a reduction in b-wave amplitude varying from one case to another. Fluoroscein angiography demonstrated an ischemic-type alteration with epitheliopathy opposite the hyper-reflective zone. Pedigree examinations suggested a familial predisposition. The histological examination indicated photoreceptor degeneration that was more pronounced in the central tapetal zone. In France, retinopathy in the Bernese Mountain Dog involves an early retinal degeneration that produces specific manifestations of the ocular fundus, night visual impairment or blindness, and has familial transmission.

Animals↗
PubMed1998

Case report of Usher's syndrome in two sisters--first reported case in Singapore.

A 28-year-old Chinese woman presented with poor night vision since childhood. Ocular examination showed pigmentary retinopathy and systemic examination revealed sensorineural hearing loss. Family history showed a similar condition in her youngest sister. Ocular and systemic examination of her sister showed similar findings. This is presented as the first case report of Usher's syndrome in Singapore. A general discussion of Usher's syndrome is also presented.

Adult↗
PubMed1980

The morphology of the cat tapetum lucidum.

Tapetum lucidum is a comparatively neglected structure found in many species used in vision research. Fundus photography and light and electron microscopy were used in this study to provide more information about the macro- and microstructure of this reflectant layer. In the cat, the tapetum is a lamellar choroidal structure formed by (in cross-section) rectangular cells containing groups of parallel crystal rods. Within each cell these groups of rods lie at various angles to each other but in a plane approximately parallel to the retina. The basal lamina (Bruch's membrane) is poorly developed or absent, and the retinal pigment epithelium contains relatively few pigment granules. It is thought that the function of tapetum lucidum is to reflect light that has not stimulated the retina back into the receptor cells for a second chance of absorption by the visual pigments, thus enhancing night vision.

Animals↗
PubMedDate not supplied

Wavefront-guided treatment for previous laser in situ keratomileusis and photorefractive keratectomy: case reports.

PURPOSE: To describe the off-label use of the Alcon LADARVision System for CustomCornea (LADARWave and LADARVision4000) in two patients, one for retreatment after laser in situ keratomileusis (LASIK) and one for retreatment after photorefractive keratectomy (PRK). METHODS AND RESULTS: Both patients were unhappy with the quality of their vision after initial refractive surgery. The first patient initially had LASIK to correct -4.75 D of myopia in each eye, and then had retreatment with CustomCornea. Before retreatment, manifest refraction was OD 0.50 -0.50 x 180 degrees (20/25 uncorrected) and OS -0.50 -0.75 x 180 degrees (20/40 uncorrected). Two months after retreatment with CustomCornea, his uncorrected visual acuity OD was 20/15, and 1 month after retreatment in his left eye, uncorrected visual acuity was 20/15. The second patient had PRK OD, with a postoperative uncorrected visual acuity of 20/25 and cycloplegic refraction of +1.00 -0.75 x 84 degrees. After CustomCornea retreatment, his 3.5-month postoperative uncorrected visual acuity was 20/15 and manifest refraction was +0.50 -0.50 x 180 degrees. CONCLUSION: The Alcon LADARVision System for CustomCornea was used effectively to retreat both a myopic LASIK and myopic PRK patient, primarily for subjective quality of night vision complaints.

Adult↗