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AimsTo compare the efficacy of the high specificity Frequency Doubling Technology (FDT) Perimeter Screening Program (C-20-1) to standard threshold automated perimetry in the diagnosis of open-angle glaucoma.MethodsA total of 100 consecutively presenting patients attending a glaucoma clinic who volunteered for the study (approximately 30% of whom were attending for an initial visit) were examined with the FDT C-20-1 Screening Program and with the Humphrey Field Analyzer (HFA) SITA Fast algorithm and Program 24-2.ResultsOf the patients, 17 were excluded due to unreliable visual field results or non-glaucomatous ocular abnormalities. In all, 10 patients were diagnosed as normal, 54 with open-angle glaucoma, eight with ocular hypertension, and 11 as glaucoma suspects. Of the 54 glaucomatous patients, 45 exhibited high-tension glaucoma and nine normal tension glaucoma. Perimetry with the HFA gave a sensitivity of 81.5% for the combined category of glaucoma and glaucoma suspect and a specificity of 83.3% for the combined category of normal and ocular hypertension. Perimetry with the FDT gave a sensitivity of 74.5% and a specificity of 85.2% compared to that of the HFA.ConclusionIn the detection of glaucoma, Program C-20-1 of the FDT perimeter exhibits high specificity. It exhibits low sensitivity for the detection of mild loss but high sensitivity for advanced field loss relative to Program 24-2 and the SITA Fast algorithm of the HFA.Eye (2006) 20, 681–687. doi:10.1038/sj.eye.6701946; published online 24 June 2005 [ABSTRACT FROM AUTHOR]

It has been suggested that variations found in colour vision upon repeated testing may be due to fluctuations in the plasma glucose level, but the results of studies to date are conflicting. Therefore, the aim of this study was to investigate whether a short-term increase in plasma glucose concentration had an influence on colour vision in patients with non insulin-dependent diabetes mellitus (NIDDM) (n = 16). The colour vision and plasma glucose levels were monitored every 30 mm for a total period of 4h during three test conditions: two when the plasma glucose levels were increased by the administration of glucose, either orally (n =8) or intravenously (n = 8), and one when the plasma glucose was relatively stable during lasting conditions (n = 8). The results indicate that the colour vision, as assessed by the Desaturated Dl 5, appears to be unaffected by the short-lived increases in plasma glucose concentrations. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the visual functions of a group of young insulin dependent diabetes mellitus patients (IDDMs), (n = 42) with an age and sex matched control group (n = 24). Examinations were carried out every 3 months for 2 years. There were no significant differences in visual acuity between IDDMs and control subjects. The IDDMs made significantly more errors with the desaturated D15 compared with the control group (P < 0.05). The contrast sensitivity for the IDDMs was tower at each spatial frequency compared with the control group, being significantly different from 3 c/deg and above (P < 0.05). A negative correlation was found between HbA[SUB1] and contrast sensitivity at 6 and 12 c/deg; as the HbA[SUB1] increased the contrast sensitivity decreased (P < 0.05). As the blood glucose level decreased, the colour vision deteriorated (P < 0.05). There was no significant difference between the visual performance of those IDDMs with retinopathy (n = 5) compared to those without. [ABSTRACT FROM AUTHOR]

A total of 189 cases with amblyopia, where atropine sulphate 1 % had been used as a method of unilateral occlusion, were reviewed. The results show that after atropine had been appropriately applied, permanent reversal of amblyopia is rare, and unwanted side-effects are few and of minor nature. Pupil size, light reflex and accommodation of the atropinized eye appear to be unaffected. The angle of squint was unaffected and fixation of the amblyopic eye either remained unchanged or shifted to a more central point. [ABSTRACT FROM AUTHOR]

It has been postulated that diabetic retinopathy might be initiated by hypoxia during the hours of darkness. Oscillatory potentials, which reflect inner retinal function, are reduced in diabetic patients. We tested the effect of oxygen inhalation on the amplitude of these oscillatory potentials after dark adaptation in seven patients with type 2 diabetes and eight controls. We found that the decreased oscillatory potentials induced by dark adaptation in the diabetic patients increased during oxygen inhalation to an amplitude that was not significantly different from that of the controls before oxygen. Oscillatory potentials in the controls were unaffected by oxygen. This finding strengthens support for the suggestion that diabetic patients might benefit from sleeping with night-time illumination. [Copyright &y& Elsevier]

The effect of diabetes mellitus on the normal dark adaptation curve is investigated. It has been found that diabetic patients take longer to adapt and that their absolute thresholds are raised. The degree of elevation in the final threshold correlates with the duration of diabetes. [ABSTRACT FROM PUBLISHER]

A response by R. V. North and M. E. Kelly to a letter to the editor about their article "Uses and adverse effects of topical administration of atropine" in the April 1987 issue is presented.

Objectives: To determine the incidence of any and referable diabetic retinopathy in people with type 2 diabetes mellitus attending an annual screening service for retinopathy and whose first screening episode indicated no evidence of retinopathy., Design: Retrospective four year analysis., Setting: Screenings at the community based Diabetic Retinopathy Screening Service for Wales, United Kingdom., Participants: 57,199 people with type 2 diabetes mellitus, who were diagnosed at age 30 years or older and who had no evidence of diabetic retinopathy at their first screening event between 2005 and 2009. 49,763 (87%) had at least one further screening event within the study period and were included in the analysis., Main Outcome Measures: Annual incidence and cumulative incidence after four years of any and referable diabetic retinopathy. Relations between available putative risk factors and the onset and progression of retinopathy., Results: Cumulative incidence of any and referable retinopathy at four years was 360.27 and 11.64 per 1000 people, respectively. From the first to fourth year, the annual incidence of any retinopathy fell from 124.94 to 66.59 per 1000 people, compared with referable retinopathy, which increased slightly from 2.02 to 3.54 per 1000 people. Incidence of referable retinopathy was independently associated with known duration of diabetes, age at diagnosis, and use of insulin treatment. For participants needing insulin treatment with a duration of diabetes of 10 years or more, cumulative incidence of referable retinopathy at one and four years was 9.61 and 30.99 per 1000 people, respectively., Conclusions: Our analysis supports the extension of the screening interval for people with type 2 diabetes mellitus beyond the currently recommended 12 months, with the possible exception of those with diabetes duration of 10 years or more and on insulin treatment.

Purpose: To evaluate the diagnostic power of a novel digital stereoscopic imaging system in the diagnosis of glaucomatous optic neuropathy., Design: Prospective cross-sectional analysis of the diagnostic accuracy of digital stereoscopic optic disc analysis in the diagnosis of glaucomatous optic neuropathy exhibiting mild to moderate field loss., Participants: Fifty-two patients with open-angle glaucoma and 54 normal individuals were recruited. The presence of a reproducible visual field loss characteristic of glaucoma was used as the reference standard for the presence of glaucoma independent of the optic nerve head appearance. Patients were excluded if the optic disc, fundus, or visual field indicated other disease. One eye from each patient and individual was included in the study, the eye with the least field loss and a randomly designated normal eye, respectively., Methods: Simultaneous stereoscopic optic disc photography was performed on each specified eye. Three experienced observers viewed the resultant stereoscopic image of each nerve head using a Z screen, recorded a subjective clinical diagnosis, and undertook digital stereoscopic planimetry. Separate linear regression analysis was performed, post hoc, from the planimetric results for each observer of the logarithm of neuroretinal rim (NRR) against optic disc area derived from each normal eye. Eyes with NRR areas below the 95th prediction interval of the normal cohort were then classified as glaucomatous., Main Outcome Measures: Sensitivity and specificity for the detection of glaucomatous optic neuropathy., Results: With subjective stereoscopic analysis, sensitivity for glaucoma detection among the 3 observers was 80.8%, 76.9%, and 90.4%, with respective specificities of 94.4%, 79.6%, and 79.6%. Regression analysis of the NRR in 30 degrees segments gave sensitivities between 69.2% and 80.8% and specificities between 83.3% and 90.7%. A combination of the subjective and quantitative analysis did not significantly improve discrimination., Conclusions: The subjective analysis of digital stereoscopic images provides a useful method for the discrimination of normal and glaucomatous optic nerves. Planimetric analysis does not significantly improve the diagnostic precision of this technique.

Background/aims: To determine the reproducibility of the Humphrey optical coherence tomography scanner (OCT), software version 5.0, for measurement of retinal nerve fibre layer (RNFL) thickness in normal subjects and to compare OCT measurements with published histological thickness of the human RNFL., Methods: Three independent measurements were obtained at each session for one eye from 15 normal subjects with a mean age of 30.8 (SD 10.9) years. Scans were taken in the peripapillary retina using the default setting (1.74 mm radius from centre of the optic disc) and were repeated 1 week later. Additional scans were obtained at the optic nerve head (ONH) margin overlying the scleral rim, for comparison with available histological data on the human RNFL., Results: For the 1.74 mm circular scan, the mean coefficient of variation (COV) for the global RNFL thickness measurement was 5% (SD 3%). This increased to 8% (3%) for quadrant measurements and to 9% (3%) with further subdivision into 12 segments. Significant differences (p<0.05) between sessions were only found when the data were divided into segments. The mean RNFL thickness for the 1.74 mm scan was 127.87 (9.81) microm. The RNFL was maximal at the superior disc pole, 161.44 microm (14.8), and minimal at the temporal pole, 83.1 (12.8) microm. Peak thickness values occurred superior temporal and inferior temporal to the vertical axis. RNFL thickness for every sector of the disc was greatest at the margin of the optic disc (mean 185.79 microm; SD 32.61). Although the variation in RNFL thickness around the disc follows published histology data, the OCT underestimates RNFL thickness by an average of 37% (SD 11; range 21-48%)., Conclusion: The OCT provides reproducible measurement of the retinal structures that are consistent with the properties of the RNFL. However, comparison with available studies of RNFL thickness in the human suggests that in its present form, the OCT underestimates RNFL thickness. Further refinement of this technology is required to improve the accuracy with which the OCT measures retinal nerve fibre layer thickness.

Purpose: To determine effects of astigmatism and working distance on optic nerve head images in normal patients using the Heidelberg Retina Tomograph., Methods: The optic disks of 51 normal healthy subjects, aged 19 to 44 years, were imaged through dilated pupils. Subjects with 0.75 DC or less of astigmatism were imaged without correction at a working distance of 15 mm. They were then re-imaged with a cylindrical correction of +3.00 DC at 90 degrees axis (n = 20). Naturally astigmatic subjects with more than 1.00 DC were imaged without correction and then re-imaged once this was neutralized with their appropriate spectacle prescription (n = 15). The effects of working distance were studied using subjects with 0.75 DC or less (n = 16). Two working distances were used, 15 and 25 mm. At each session the means of three topographic images were taken from which standard deviations and parameters were recorded. Parameters analyzed included cup shape measure, rim area, and inferior temporal rim volume. Z-profile full width at half maximum was calculated from one image per subject for each condition., Results: No significant difference was found in the measured parameters of the optic disk for any astigmatic condition or changes in working distance (P >.05), (paired t test). Both the standard deviation of the mean topographic images and the Z-profile half-maximum width of the axial intensity profile were significantly greater with induced astigmatism of +3.00 DC (P values 0.3 and.00, respectively)., Conclusions: Optic disk parameters are not significantly affected by uncorrected astigmatism (up to 2.50 DC) or working distance. The algorithm used by the Heidelberg Retina Tomograph to generate topographic maps is sufficiently robust that astigmatism up to 2.50 DC does not require correction.

Purpose: To compare the sensitivity of the photopic negative response (PhNR) from the shortwave (S)-sensitive and the long (L)- and medium (M)-wave-sensitive cone electroretinograms (ERGs), with the pattern electroretinogram (PERG) in the early stages of primary open-angle glaucoma (POAG)., Methods: Eighteen patients under treatment for diagnosed POAG and 19 normal control subjects were investigated. S-cone ERGs were elicited using adaptation to 650-nm light to suppress L-cone activity, and substitution between 450 nm and 535 nm to silence M-cone response at luminances higher than rod saturation. PhNRs from the L&M-cone pathways were elicited by a 200-msec pulse of red light (650 nm) on a continuous blue (450 nm) background. PERGs were recorded in accordance with the International Society for Clinical Electrophysiology of Vision (ISCEV) standard., Results: Each method showed a statistically significant difference in the two groups. The S-cone PhNR was the most sensitive test and provided the most statistically significant results, with the largest area enclosed by the receiver operating characteristic (ROC) curve., Conclusions: The findings indicate that all three types of ERG may be useful in glaucoma investigation. The L- and M-cone PhNRs may have a role in monitoring established glaucoma. The previously reported high sensitivity of the PERG was confirmed. Extensive diffuse damage to S-cone bipolar and bistratified ganglion cells appears to occur at a very early stage in POAG, owing to a pressure-related mechanism, and the S-cone PhNR was the most sensitive test. It may in future have an important role in diagnosis and monitoring of early glaucoma. Further investigation of this possibility is recommended.

This article aims to review the early indications of diabetes, both ocular and non-ocular. Epidemiological data is showing an increase in both non-insulin dependent and insulin dependent diabetes mellitus. It is therefore important that diabetes mellitus is detected early so that regular screening and good metabolic control can be encouraged. Strict glycaemic control is important in order to delay the onset or slow the progression of diabetic complications.

The most important cues to the normal vergence response are retinal disparity, accommodative effort and perceived distance (proximal cue). In the past, proximal cues have been thought to contribute little to the total vergence response but more recent studies have suggested that they play an important role. The relative contributions of the proximal, accommodative and disparity cues to the vergence response were assessed by measuring the effect upon the vergence system when each of these cues were altered. The effect upon the vergence system was measured by the change in 'phoria, the change of fixation disparity and the amount of prism adaptation after 210 s of binocular viewing. The results indicate that the greatest effect of cue disharmony occurred when the proximal and disparity cues were altered. A finding which signifies the importance of the proximal cue to the overall vergence response.

It has been suggested that the wearing of band-pass tints may improve the contrast performance in certain ocular conditions. We examined this by measuring grating visual acuity (VA) for targets of various contrasts. The benefits of Corning CPF 511, 527 and 550 lenses, and neutral density (ND) filters were examined with and without the presence of glare. Generally, patients with anterior sector conditions showed improved performance with band-pass filters (not with ND filters). It is suggested that the filter reduces the scatter within the ocular media. People with retinitis pigmentosa or diabetic retinopathy rarely benefited. The CPF 511 most frequently improved VA followed by CPF 527 and 550 respectively. We suggest that a condition of glare is incorporated when assessing suitability with tints.

Previous studies have shown that subjects with normal binocular vision adapt to prism-induced phorias. However, there are conflicting reports as to the amount of adaptation shown to horizontal prisms. Some investigations found a greater amount of adaptation to base out prisms compared with base in, whilst others found the reverse and one study found no adaptation to base out prism at all. This study investigated the adaptation response to horizontal prisms at distance and near in a larger number of subjects (n = 40). The results confirmed our previous findings and showed that at distance the adaptation responses are asymmetrical, there being a significantly greater amount of adaptation to base out prism compared with base in, whilst at near the responses are virtually symmetrical. Possible reasons for these findings are discussed.

Vergence adaptation response monitored with various prism disparities demonstrated that the rates of adaptation decreased as the prismatic effect was increased. However, the amount adapted increased with the increase in the value of the prism until this value fell outside the fusional amplitude; the amount adapted then decreased. However, a large disparity can be adapted to with ease if the prismatic effect is increased gradually in small steps. The clinical implications of these results are discussed.

In previous studies the ability of the oculomotor system to adapt to prism-induced heterophoria has been shown. The 'phoria that occurs immediately after a prism has been placed before one eye gradually reduces and returns to its original baseline value as the subject is allowed binocular experience while wearing the prism. Little work has been carried out to determine when the adaptation is complete. In this study we report on the results of two experiments designed to determine when adaptation is complete. In the first, the rate of decay of adaptation, i.e. loss of slow fusional vergence, is measured after varying periods of forced vergence. In the second experiment the rate of adaptation to an additional disparity is measured; this should be the same as that before the induced effect if adaptation is complete. The results of this study indicate that although adaptation may appear complete by the criterion that the 'phoria has returned to its baseline value, the adaptation is unlikely to be truly complete for a much longer period of time has passed.

Atropine is used widely in the treatment of a variety of ocular conditions. This article reviews the uses of atropine in children and any adverse ocular or systemic side effects that have been reported after topical instillation.

In a previous study we showed that subjects with abnormal binocular vision either lacked or had a deficient ability to adapt their oculomotor systems to a prism-induced heterophoria. In this study we report on the results of an experiment designed to establish whether the adaptation ability improves in patients who are successfully treated, by means of orthoptics, for convergence insufficiency. In all seven patients examined, we found an improved ability to adapt. Whereas at the beginning of the experiment only two patients fell within the 95% confidence limits of the norm, at the end five patients fell within these limits. These results demonstrate that the success of orthoptics in relieving symptoms is associated with an improved ability to adapt to prism-induced heterophoria.

The effect of the extent of visual field upon driving performance has recently received a great deal of interest. With such a volume of traffic on the roads today, peripheral vision would seem to be essential for safe driving and yet past literature is inconclusive as to the relationship between the extent of visual field and driving performance. This paper reviews the research work and gives possible reasons for the lack of relationship reported in most of the studies. Until further research work does determine the minimum visual field required for safe driving, the role of the medical practitioner in advising patients when they are considered unsafe to drive is in question. The provision of a period of adaptation after complete loss of vision in a previously normal eye should also be considered, during which time the motorist is temporarily banned from driving.