摘要:

The optical quality of the human fovea was assessed by measuring the modulation of aerial fringes conjugate with the retina. The different possible causes of the decrease in modulation of this pattern were successively investigated, the main one being the passage through outer segments in unguided modes. Modulation diagrams measured on the fovea were compared with those of the perifovea.

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00806.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The optical matrices for modified schematic eyes are derived. The primary modification is to replace the usual isoindicial or bi‐indicial crystalline lens with a polyindicial lens so as to more closely approximate the living human lens. Further modifications are made to simulate the accommodated state. The use of optical matrices to solve an optometric problem is demonstrate

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00807.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

One of the most common indications for the fitting of therapeutic contact lenses is bullous keratopathy, a painful condition often iatrogenic in origin and more usually encountered in elderly patients. A retrospective study of 30 patients fitted with therapeutic lenses for the condition and followed up for at least a year showed that the symptoms of bullous keratopathy were reduced in most cases. There was a higher incidence of suppurative keratitis (13 per cent) than has been reported in previous series. The prescribing of prophylactic antibiotics was haphazard in the series, and the authors suggest further study is needed to determine their precise role.

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00808.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Refraction and optical components have been measured in 36 eyes using objective optometry, keratometry, ophthalmophakometry and A‐scan ultrasonography. A computing scheme was used to confirm that the accumulated experimental errors for a phakometric technique tend to exceed the inherent errors of a new method which calculates the equivalent powers of the eye and its crystalline lens without resort to phakometry. Bennett's method was shown to be a valuable technique in biometric studies which obviates the need for lengthy experimental investigation

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00809.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Pre‐and post‐task tonic accommodation (TA) was measured using an objective infra‐red optometer under two open‐loop conditions: a darkroom and a bright empty‐field (60 cd m‐2). The task was of 10 minutes' duration and was located at —1, —3 and —5 D. Post‐task TA was measured immediately after the task and over a period of 90 s. Mean data for the group of 10 young men subjects showed that the open‐loop condition adopted had no significant influence on the post‐task regression patterns of TA towards pre‐task values. Three subjects did, however, show significantly more sustained increases in post‐task TA for the bright‐field condition; one markedly so. Conversely, two subjects showed more pronounced post‐task sh

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00810.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Recent reports suggest that the higher frequency components (around 2 Hz) of accommodative fluctuations may arise from the accommodative ‘plant’ and may have no role in the control of the accommodation system. The dynamic responses of accommodation in two cases with Adie's syndrome were recorded. The results showed that the velocity of accommodative responses was reduced, and the accommodative fluctuations in the higher frequency components were completely diminished. It can be concluded that the origin of fast fluctuations is not located at a more peripheral site than the lesion of tonic accommodation. Since the possible lesion exists at the ciliary ganglion, the origin of the fast oscillation may not be the accommodative ‘plant’, but the neu

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00811.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

A method is described where the surface curvatures and axis orientation of a toroidal surface can be determined by measuring the lens in three fixed orientations. This method also has possible applications in the measurement of progressive addition lenses.

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00812.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Three methods of measuring aberrational astigmatism in progressive addition spectacle lenses are described. Measurements are presented from each method made on an Essilor Varilux 2 lens, which illustrate the small differences between the methods for low power lenses.

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00813.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Sources and magnitude of errors in applying Prentice's rule in calculating decentration for spherical lenses were investigated. It was found that spherical aberration can be the only source of error in applying the rule. The overall magnitude of errors in effective prismatic effect is, however, clinically insignificant.

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00814.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00815.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY