摘要:

We analyzed data from 4 orthokeratology studies of refractive error change (ARE) and keratometer-reading change (ΔK). Instead of the reported ΔRE/ΔK ratio of 2:1, we calculated from linear-regression analysis a ratio (slope) of 2:3. The ordinate intercept of the straight line fitted to the data (N = 181 eyes) indicates that when ΔK = 0, ΔRE = 0.72. The correlation between ΔK and ΔRE is poor (+0.63). Causes and interpretations of these results are discussed.

ISSN:0093-7002    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

Marginal astigmatism and longitudinal chromatic aberration were measured (with a modified Vertometer) for +2-D bifocal lenses of different designs, base curves, and major-lens powers. At a reading level 20 deg below the pole of the major lens, deterioration of the optical image occurred and was created by the interaction of marginal astigmatism (tangential error) and lateral chromatic aberration (prismatic dispersion). Suggestions for selecting an optimal bifocal-lens design for different types of refractive error are presented.

ISSN:0093-7002    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

Measurements were made of the amplitude of accommodation for myopes wearing spectacles, rigid contact lenses, and flexible contact lenses. Both forms of contact lenses placed greater accommodative requirements on the myope than did spectacle correction, but no significant difference was found between the 2 types of contact lenses in this respect.

ISSN:0093-7002    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

We studied the relation between eccentricity of monocular fixation and the minimum angle of resolution in visually normal subjects and in both the amblyopic and dominant eyes of amblyopes. For the amblyopic and visually normal eyes, this relation was linear; resolution was poorer at the eccentrically fixating locus than at the corresponding region of the normal eye. The dominant eyes of the strabismic amblyopes had a nasal component of eccentric fixation that was less than that of the companion amblyopic eyes, but greater than that found in the visually normal eyes. In terms of the eccentricity of monocular fixation, the dominent eyes of strabismic amblyopes were different from the normal eyes.

ISSN:0093-7002    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

The author discusses practical issues relating to optometrists ordering and laboratories supplying ophthalmic lenses that meet the ANSI Z80.1 Standard (1972) for minimizing unwanted spherical and cylindrical power in the periphery of lenses. He spells out the optical principles and formulas needed to develop a computer program than can be used by optometrists and opticians for designing lenses that meet the Z80.1 Standard.

ISSN:0093-7002    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

The cornea requires a minimum level of oxygenation; this may De prevented by a contact lens, and corneal swelling and other undesirable effects may result. By employing thin-film lubrication theory, this study derives analytical solutions for the tear-film velocity components and pressure under a circular contact lens. Oxygen-tension contours are then obtained for various values of squeeze action and parallel motion of the lens.

ISSN:0093-7002    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

We measured the sizes of the test forms (letters, digits, and symbols) on 19 different near-point acuity cards. The results are all expressed in the M notation (1 mm of letter height equals 0.7 M) and are tabled according to the acuity specification system used by the manufacturers-such as, the point-type system, Jaeger notation, equivalent 20-ft Snellen notation, and so on. Our results demonstrate that manufacturer's specifications on near-point acuity cards cannot be used to determine the sizes of test letters. The M system has sufficient advantages over other systems to warrant its universal use for specifying near-point visual acuity.

ISSN:0093-7002    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

The background and reasons for using the code AOPOCF on this JOURNAL'S cover are presented.

ISSN:0093-7002    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

A dark adaptometer that was designed for student-laboratory use is described and advocated for use in optometric practice because of its simplicity, accuracy, and low cost. Representative dark-adaptation results obtained from 2 naive and 2 sophisticated subjects are presented.

ISSN:0093-7002    

出版商:OVID    

年代:1977

数据来源: OVID

ISSN:0093-7002    

出版商:OVID    

年代:1977

数据来源: OVID