ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00796.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Albinism is not a single entity but represents a heterogenous group of inherited disorders of pigmentation. Despite a wide variety of manifestations, all forms of albinism are characterized by several ocular features, including: nystagmus, photophobia, reduced visual acuity and a lack of stereopsis. It is the intention of this review to describe and discuss the clinical implications of albinism with particular emphasis placed on these ocular features and their effects on visual performance. Various techniques that may be employed to aid the albino will also be described.

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00797.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The medical treatment of cataract now appears to be a distinct possibility. A number of anti‐cataract formulations are being clinically tested, and more clinical trials are being planned. To obtain a true assessment of a drug's efficacy, a battery of tests are needed which can accurately assess cataract progress. A clinical trial of the proposed anti‐cataract drug Bendalina is being conducted. The six subjective methods used to assess cataract progression in the trial are presented. These are refractive error, LogMAR visual acuity, contrast sensitivity, glare sensitivity, retinal visual acuity and displacement threshold hyperacuity. The reasons for using each technique and their method of measurement is explai

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00798.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Visual acuity and displacement threshold hyperacuity were measured in a group of patients awaiting cataract extraction, and this was repeated several weeks subsequent to surgery. In addition, measurements were made on a group of patients with various ocular pathologies but without the presence of cataract. Displacement thresholds in the cataract group increased only slightly with the severity of the opacity. On the other hand, displacement thresholds for the pathology group showed a marked dependence upon visual acuity‐the worse the acuity, the higher the threshold. This results in a clear distinction between vision loss due to optical factors (cataract) and retinal/neural factors. There was a good correlation between pre‐and post‐operative displacement thresholds in the cataract group, with post‐operative thresholds being slightly better than pre‐operative thresholds. The results suggest that this technique may offer patients a good indication of the likely quality of vision achieved following cataract e

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00799.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

LogMAR visual acuity, contrast sensitivity and glare sensitivity measurements were made on 39 eyes of 18 cataractous subjects and compared against normative data. Only cataracts of one of the main three morphological cataract types were used‐cortical, nuclear and posterior subcapsular. Results indicate that contrast sensitivity decline with cataract is an intermediate and high spatial frequency loss. For nuclear and cortical cataracts with a LogMAR visual acuity of less than 0.5 (Snellen equivalent better than 6/18), there was no loss of contrast sensitivity at the lowest spatial frequency (1 c/deg). For posterior subcapsular cataracts, low spatial frequency contrast sensitivity loss did occur but was unrelated to visual acuity. Glare sensitivity increased for all cataract types. This was related to visual acuity for both cortical and nuclear cataracts but was not for the posterior subcapsular type. It was concluded that contrast and glare sensitivity measurements are a useful part of the assessment of visual function in patients with posterior subcapsular catarac

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00800.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

In a survey of nearly 75000 eye examinations, 6% of patients were referred to a medical doctor and the doctor was notified in a further 2% of cases. The level of referral was 2% higher than in 1986; 70% of referrals were the result of reminders or periodic attendances, and 80% of those referred were over 40 years of age. The general pattern of referral was broadly in agreement with a survey conducted in 1986 but indicates that some categories of eye conditions are being referred at a higher rate.

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00801.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Using paraxial equations, the change in dioptric power of the crystalline lens required to image objects at given distances from the eye, on the retina, is calculated. This shows that the depth of the anterior chamber affects crystalline lens accommodation more than other variables. The relationship between anterior chamber depth and presbyopia, and a possible geographical aspect, are discussed.

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00802.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Instillation of three drops of 0.025 % hyoscine hydrobromide into one eye at 5 min intervals caused a mydriasis and cycloplegia of rapid onset and of 4–6 days' duration; this was similar to the previously reported actions of concentrations of up to 0.5%. After refraction for the working distance of the experiments, contrast sensitivity to stationary oscilloscope‐generated grating patterns of 10 and 20 c/deg was unaffected despite the mydriasis. Also, contrast sensitivity to laser interference fringes of 10 and 20 c/deg observed in the Maxwellian view, in which the effects of the ocular media are bypassed, was unaffected. Contrast sensitivity to a 3 cydeg phase‐reversed grating pattern was, however, transiently reduced by 40% after hyoscine. A second series of experiments showed a deleterious effect of hyoscine on contrast sensitivity to both stationary and phase‐reversed grating patterns of 2, 3 and 5 c/deg while contrast sensitivity at 10 c/deg was not consistently affected. These results were explained by a direct deleterious action of hyoscine at the level of the retina, specific to channels that detect low spatial freq

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00803.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Previous work has shown that binocular contrast summation, obtained with equal monocular sensitivities, remains constant over a range of spatial frequencies. We measured binocular contrast detection with a log 1.00 ND filter placed in front of one eye. For all eight subjects, the binocular contrast detection decreased to a level below that of the monocular detection, demonstrating a contrast analogy to Fechner's paradox. The degree of binocular inhibition, like summation, remained constant across the range of spatial frequencies.

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00804.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The rotations and retractions of the eyeball due to co‐contraction of the extraocular muscles are investigated using a model of the mechanics of the orbital plant. The hypothesis that the rotational movements are secondary to globe retraction is not supporte

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1989.tb00805.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY