Abstract:
BACKGROUND:Optical aberrations induced by the transition zone of a myopic photorefractive keratectomy (PRK) may degrade the image quality. The subjectively evaluated visual acuity and contrast sensitivity may be reduced significantly especially with mydriasis. The purpose of this study was to calculate the image forming properties of the eye using raytracing techniques of a spot light source based on topographic height data of a scanning slit videokeratoscope. METHODS:Refractive surfaces were calculated from raw height data sets of the anterior and posterior corneal surface measurements (Orbscan, Orbtec, USA). The characteristics of the residual refractive surfaces were derived from Navarro's eye model. The focal distance was calculated using the exact raytracing calculation. Point spread function was determined at the focal plane and at 5 (delta = 0.2 mm) parafocal planes in front of and behind the focal distance in accordance to the pupil diameter (2, 3 and 6 mm). The algorithm was applied to 11 selected eyes (6 left, 5 right) of 8 patients before and after PRK with myopia (n = 6) and myopic astigmatism (n = 5). RESULTS:Before PRK the focal distance did not decrease significantly with increasing pupil size (2 to 6 mm), but decreased significantly after PRK (-0.41 +/- 0.12 mm, p = 0.02). Preoperatively, the variance of the point spread function did not differ significantly between a 2 mm (0.046 +/- 0.015 mm) and a 6 mm (0.055 +/- 0.021 mm) pupil size but was affected significantly by the pupil size postoperatively (2 mm: 0.049 +/- 0.018 mm, 6 mm: 0.096 +/- 0.045 mm, p = 0.04). CONCLUSIONS:Raytracing of corneal topography height data based on refined eye models with the option of calculation of the focus has the potential of tracing the optical resolution of the eye as a function of the pupil size. Due to of the altered surface geometry of the cornea after myopic PRK, both the variance of the point-spread function and the depth of focus increase with pupil size. This may be an explanation for impaired subjective refractometry and reduced contrast sensitivity of the patient after conventional keratorefractive surgery.
journal_name
Klin Monbl Augenheilkdjournal_title
Klinische Monatsblatter fur Augenheilkundeauthors
Viestenz A,Seitz B,Langenbucher Adoi
10.1055/s-2001-16297subject
Has Abstractpub_date
2001-07-01 00:00:00pages
498-502issue
7eissn
0023-2165issn
1439-3999journal_volume
218pub_type
杂志文章abstract:BACKGROUND:The intravitreal injection of an anti-VEGF compound is the current standard of care in neovascular AMD. The response to this therapy varies greatly. To date it was not possible to determine clear predictive factors in regard to therapy response, thus making it difficult when counselling patients regarding th...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-0031-1299250
更新日期:2012-04-01 00:00:00
abstract::Increased blood sugar levels may influence the refractive power of the lens in juvenile diabetics, and can lead to the rare true diabetic cataract ("snow-storm cataract"). Surplus glucose induces accumulation of the sugar alcohol within the cells, thus generating disturbances of the osmotic balance and finally causing...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1050822
更新日期:1986-11-01 00:00:00
abstract:BACKGROUND:Disturbances in the microcirculation are a source of retinal diabetic alterations. Comprehensive studies of blood flow parameters have been performed, but it is not known how ageing, duration of diabetes, blood sugar, glycolysed haemoglobin and elevated systemic blood pressure act in the early stages of diab...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2007-963156
更新日期:2007-05-01 00:00:00
abstract:BACKGROUND:The aim of this study was to evaluate retrospectively the clinical outcome of retinal photocoagulation of age-related juxtapapillary choroidal neovascularisation (CNV) with macular oedema. Juxtapapillary CNV represents a rare form of extrafoveal CNV in age-related macular degeneration (AMD). PATIENTS AND ME...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-0031-1273430
更新日期:2011-11-01 00:00:00
abstract::Forty-six patients with in most cases severe vascular degenerative retinochoroidal circulatory disturbances or with glaucomatous visual field defects were treated with rökan dragées (160 mg/day for four weeks, then 120 mg/day). The following were checked at monthly intervals to determine the degree of success of the t...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:
更新日期:1980-11-01 00:00:00
abstract:BACKGROUND:A broad differential diagnosis has to be considered in a patient with swollen discs. Myeloproliferative disorders such as leukemia and lymphoma can in rare cases cause infiltrative optic neuropathy. HISTORY AND SIGNS:Two patients initially presented with slowly progressive severe visual loss. History was un...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2004-812857
更新日期:2004-05-01 00:00:00
abstract::The treatment of retinal detachments due to macular holes without further central peripheral holes with intraocular tamponades (SF6, silicone oil) is preferred to episcleral techniques. After treatment of 24 cases of retinal detachments due to macular holes a therapeutic program is proposed. ...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1054385
更新日期:1985-12-01 00:00:00
abstract:BACKGROUND:In April 1986, numerous reactor workers and firemen were exposed to high doses of ionizing radiation during the Chernobyl nuclear power plant accident. Apart from high ambient gamma-ray exposures they received inhomogeneous contamination with beta-rays from fission products, resulting in severe skin exposure...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1034732
更新日期:1999-12-01 00:00:00
abstract::Although luetic ocular changes are rarely seen today they should not be neglected in differential diagnosis. Luetic papilledema is extremely rare and neurologic symptoms may be minor. A clinically observed case is described. ...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:
更新日期:1979-12-01 00:00:00
abstract::It is the object of this paper to familiarize the ophthalmologist with some modern epidemiological techniques and to present examples of their application to a consideration of the influence of the level of intraocular pressure on the development of the type of visual field loss characteristic of primary open angle gl...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1054461
更新日期:1984-04-01 00:00:00
abstract::Congenital, bilaterally symmetrical dislocation of the lens within the posterior chamber is referred to as lens ectopia. The behavior of the anterior hyaloid membrane in congenital lens ectopia has not been considered hitherto. The anterior hyaloid membrane in the aphakic area of the pupil is intact or ruptured and th...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1050519
更新日期:1987-11-01 00:00:00
abstract:BACKGROUND:Data from national graft registries suggests a limited prognosis in the group of all repeat keratoplasties. This group might rather consist mostly of cases already classified as high risk in the first place, however. Thus, repeat keratoplasties in normal risk indications might have a substantially better pro...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1027127
更新日期:2008-01-01 00:00:00
abstract:BACKGROUND:The short-term impact of eye muscle surgery on the blood-aqueous barrier has been described by iris fluoresceinangiography and laser tyndallometry. The aim of this study was to investigate the long-term effects of eye muscle surgery on the oxygen supply of the anterior segment of the eye by determination of ...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2007-962981
更新日期:2007-03-01 00:00:00
abstract::Computerized threshold perimetry of the central 30 degrees was performed on 69 eyes of 36 patients (men and women of all age groups and with different types of diabetes) one day before and one month after panretinal photocoagulation by argon laser. An average of 900 spots were placed in a chessboard pattern in three s...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1050103
更新日期:1988-03-01 00:00:00
abstract:BACKGROUND:Autoregulation is defined as the maintenance of constant blood flow in a vascular system in spite of changes in perfusion pressure (PPm). MATERIALS AND METHODS:PPm was decreased by increasing the intraocular pressure (IOP) with a suction cup and optic nerve blood flow was measured with the laser Doppler flo...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:
更新日期:1997-05-01 00:00:00
abstract:BACKGROUND:The correction of lower eyelid retraction remains a challenge with established techniques having disadvantages. A recently described alternative is implantation of an ultrathin high density porous polyethylene lower eyelid spacer (Medpor LES). We report our experience on implanting this Medpor LES, especiall...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 临床试验,杂志文章
doi:10.1055/s-2006-926508
更新日期:2006-07-01 00:00:00
abstract::A report is given on the implantation of 500 Medallion lenses, most of which were implanted after intracapsular cataract operation (88%) and were kept under observation for between 3 and 88 months (average 22 months). In 1.2% a severe keratopathy resulted from an operation that was too traumatic, from decentration of ...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1054737
更新日期:1983-02-01 00:00:00
abstract::Applanation tonometry has been the gold standard in clinical ophthalmology for more than fifty years. The most popular factor is central corneal thickness that is now routinely considered in glaucoma management. However, other individual features of the cornea can also play a key role for the interpretation of the app...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章,评审
doi:10.1055/s-0029-1246037
更新日期:2011-02-01 00:00:00
abstract::The authors report on the techniques of laser treatment of diabetic maculopathy: focal direct laser coagulation of I.R.M.A. in exudative maculopathy; laser grid photocoagulation in edematous maculopathy. ...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1050820
更新日期:1986-11-01 00:00:00
abstract::Report on a patient with several symptoms which had not previously occurred together. The main symptom is palmoplantar keratosis; further alterations were kypho-skoliosis, brachytelephalangia of the thumbs, and in the eyes, keratoconus, a cataract and electroretinographic alterations. ...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1057732
更新日期:1980-12-01 00:00:00
abstract::In the presence of leukokoria the diagnosis of retinoblastoma is usually easy when the mediae are transparent. If they are not, however, one is frequently obliged to enucleate a painful or useless eye in order to rule out this diagnosis. In a series of eight cases having undergone enucleation for this reason at the La...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1057514
更新日期:1980-04-01 00:00:00
abstract::To determine the influence of preoperative rubeosis iridis and active neovascularization at the fundus on surgical results, the authors analyzed a consecutive series of 85 eyes that underwent vitrectomy for diabetic tractional detachment of the macula. Minimum follow-up was 12 months. Rubeosis was present in 51%, acti...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1050199
更新日期:1988-06-01 00:00:00
abstract::A rare form of malignant large-cell non-Hodgkin's lymphoma or reticulum cell sarcoma is confined to the eye and central nervous system (CNS). We report the case of a 62-year-old man, who presented with recalcitrant progressive uveitis in his right eye. Although lymphoma was suspected, the patient refused to undergo vi...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1045892
更新日期:1992-09-01 00:00:00
abstract::No significant differences could be determined postoperatively between trabeculectomy and goniotrepanation. However, cases of flattened anterior chambers and choroidal detachments were less frequent after goniotrepanation than after trabeculectomy. ...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1057716
更新日期:1980-12-01 00:00:00
abstract::A 27 year old male patient with a subretinal granuloma was diagnosed as having a serologically established toxocara infection (Immunoprecipitation test in living larva). Calcifications could be demonstrated in X-ray and CT-scan imaging. The significance of calcifications for the differential diagnosis of retinoblastom...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1046304
更新日期:1990-11-01 00:00:00
abstract::A 55-year-old man was referred to our clinic with a mature, swollen cataractous lens and a secondary phakolytic glaucoma. However, the patient refused to undergo surgery. Twelve years later he returned. Meanwhile the lens had been almost completely absorbed; visual acuity was 20/32 and there had been no severe damage...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1055071
更新日期:1982-04-01 00:00:00
abstract:BACKGROUND:Pseudoexfoliation syndrome is a frequent cause of secondary open-angle glaucoma due to deposition and in situ-production of abnormal extracellular matrix proteins in the trabecular meshwork. Glaucomas itself are a known risk factor for retinal vein thrombosis. In this retrospective study the prevalence of ps...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2008-1035088
更新日期:1997-07-01 00:00:00
abstract:OBJECTIVE:Up to now, no long-term results about squint surgery with adjustable sutures have been published although it has been practiced using the current techniques since the 1970s. The aim of the study was to analyse patient satisfaction and objective findings and to compare the results to studies about squint surge...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-0033-1350912
更新日期:2013-10-01 00:00:00
abstract:BACKGROUND:Subretinal hemorrhage in age related macular degeneration (AMD) usually causes acute visual loss and is associated with poor visual prognosis. In order to prevent retinal damage and to perform laser treatment of the underlying choroidal neovascularization (CNV) the subretinal hemorrhage has to be removed fro...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:10.1055/s-2000-10513
更新日期:2000-01-01 00:00:00
abstract::The present paper exposes the shortcomings of orthoptics and proposes an original system of concomitant squint treatment named diploptics. This system is based on the new conception of the role of bifixation in the physiology and pathology of binocular vision. The major principle of diploptics is to induce diplopia un...
journal_title:Klinische Monatsblatter fur Augenheilkunde
pub_type: 杂志文章
doi:
更新日期:1978-05-01 00:00:00