The photostress recovery test in the clinical assessment of visual function

Relative foveal dark adaptation: a potential method for assessing macular health

BACKGROUND/OBJECTIVE

Dark adaptation measures photoreceptor recovery following intense light stimulation. Time to recovery reflects retinal function. We describe a novel method of relative foveal dark adaptation using an iPhone. Data from a small number of healthy subjects were studied to assess reproducibility, effects of age, and consider potential clinical utility.

METHODS

Relative foveal dark adaption was studied in 6 normal subjects across ages from 20 to 81 years and across differing testing conditions. Foveal bleaching is produced by fixating a bright white circle on an iPhone for variable times. After foveal bleaching an annular surround appears to complete a bullseye stimulus with surround initially brighter than centre. As the fovea recovers the centre regains brightness. Relative foveal dark adaptation, the time for the visual anchor to shift from surround to centre, was studied across a range of bleaching times, ages, and testing conditions.

RESULTS

Dispersion of dark adaptation times grows with increasing age. Foveal bleaching for 30 s was as effective as longer times. Testing times with a 30 s bleach were less than 1 min. Foveal dark adaptation was reproducible within each subject and was unaffected by ambient room lighting, pupil size, and light attenuation. Repeat, immediately sequential testing was similarly reproducible except after long bleaching.

CONCLUSIONS

This method of dark adaptation is intuitive, repeatable, and relatively unaffected by testing condition. Testing times are brief, requiring only an iPhone screen positioned at reading distance. Relative foveal dark adaptation may be a useful tool to assess macular health.

Painful Eyes in Neurology Clinic: A Guide for Neurologists

Eye pain is a common complaint among patients presenting to the neurology clinic. It can be related to neurologic diseases, but it can also be a localized eye condition. Such disorders can be misleading, as their benign appearance might mask more grave underlying conditions, potentially leading to misdiagnoses or delayed treatment. Clinicians should be aware of the specific neurologic or systemic disorders (eg, demyelinating diseases or vascular abnormalities) that might first manifest as eye pain. Formal ophthalmic consultation is recommended for patients presenting with eye pain as the predominant complaint especially when red flags for more serious pathology are present.

Correlation between color vision, visual acuity, contrast sensitivity and photostress recovery in the visually impaired: a cross-sectional study

Background

To investigate the correlation of colour vision, visual acuity, contrast sensitivity, and photostress recovery time test scores in visually impaired patients.

Materials and methods

A total of 133 subjects were enroled and 133 eyes were examined. The pathological group consisted of 76 (57.1%) males with an average age of 68.0 (SD=13.2) and 57 (42.9%) females, with an average age of 68.1 (SD=15.2), Mann-Whitney U test was used to evaluate the differences in K-colour tests, HRR, visual acuity, Contrast Sensitivity test and photostress recovery time test between two different groups of severity.

Results

Correlations were found among colour vision tests, visual acuity, contrast sensitivity, and photostress recovery time scores in eyes with age-related macular degeneration, with diabetic retinopathy, with optic nerve diseases, and various other retinal diseases (P<0.05). In patients with moderate-visual impairments.

Conclusions

The colour vision test scores correlate with the scores of visual acuity, contrast sensitivity, and photostess recovery time test. It may be a useful clinical surrogate for functional vision.

Reduction of Glare Discomfort and Photostress Recovery Time Through the Use of a High-Energy Visible-Filtering Contact Lens

OBJECTIVES

Glare discomfort (GDC) is the slight pain (discomfort) that arises when exposed to light that exceeds one's adaptive state. Such light can also cause a temporary loss in visual function (photostress, PS). We tested the hypothesis that filtering with a high-energy visible (HEV) light-filtering contact lens can reduce GDC and speed PS recovery time.

METHODS

Sixty-one subjects were randomized and fit with study lenses and 58 subjects completed as cohort (20-65 years of age). A double-masked, randomized, contralateral design was used (HEV filter on one eye; control lens on the other). Participants were given a 5-s exposure to a broadband white photostressor. Video images were analyzed, and palpebral fissure size during exposure was measured, as was PS recovery time to a 2-degree mid-wave target.

RESULTS

The HEV-filtering test lens was statistically superior ( P <0.0001) to the clear comparison contact lens with respect to the magnitude of squint (44.9% squint reduction) and photostress recovery time (24.3% faster recovery).

CONCLUSIONS

High-energy visible light-filtering contacts can reduce GDC and speed PS recovery. Filtering HEV light before it is incident upon the retina is a natural strategy (e.g., by the lens and macular pigment) for attenuating some of the deleterious effects of bright broadband light.

Design of a novel smartphone-based photostress recovery time test for detecting abnormalities in the macula. A cross-sectional study

Background

The study aims to present a new smartphone-based photostress recovery time test (K-PSRT test) that measures the stimulus-specific loss of visual sensitivity, as well as the differentiation between normal from abnormal macular function. This novel test defines a new standardized photostress application as an alternative tool for incorporation into clinical practice.

Materials and methods

A total of 48 visually impaired eyes and 47 normal sighted age-matched controls eyes were enrolled in the study. The median age in subjects with impairment was 71.0 years, while the median age in normal subjects was 70.0 years. A light produced by the smartphone camera at approximately 5 cm distance, perpendicular to the eye up 10 s filled the pupil. The photostress recovery time was assessed immediately after the exposure by asking the subjects to read correctly at least three successive letters of size corresponding to the previous line of the BCVA line at a distance of 40 cm. The digital photostress testing was performed with the best-corrected visual acuity (BCVA). The patients were examined twice within 2 weeks. Correlations among the recovery times, the visual acuity, and the contrast sensitivity function as well as correlations concerning each specific ocular disease were also performed. Furthermore, correlations among technology, usability, and ease of performance in both groups were analyzed.

Results

The initial median photostress recovery time in patients with impaired eyes was 83.5 (68.5, 126.0), while in the normal individuals was 39.0 (14.0, 43.0). The median visual acuity in individuals with impairment was 0.59 logMAR (0.40, 0.90), whereas in the normal individuals was -0,06 logMAR. Test-retest reliability study was performed on 26 eyes (16 males, 10 females) for visually impaired eyes as well as on 35 normal eyes (19 males, 16 females). Concerning the reliability, the average Intraclass Correlation Coefficients (with 95% confidence intervals) ICC (95% CI) = 0,99 (0,98-1,00), indicating significant correlation between them (p < 0.01). The coefficient of repeatability for eye measurements reaches clinically acceptable levels, which is demonstrated with increased repeatability and consistency. The recovery time in patients with diabetic retinopathy was statistically significantly lower than in those with dry age-related macular degeneration (p = 0.027) and those with wet age-related macular degeneration (p = 0.032). The patient group has lower scores concerning technology, usability, and ease of performance compared to the normal.

Conclusions

This new testing modality (K-Photostress Recovery time test), is designed to be an easily implemented measurement in ophthalmic practice, and it can expand our understanding of macular function. The above findings support the usefulness of a novel reproducible photostress application as an indicator of macular pathology.

Assessment of age‐related maculopathy using subjective vision tests

This paper reviews non-standard, clinical vision tests that may be used to detect the earliest visual loss in age-related maculopathy (ARM), before fundus changes are detected. We recommend a clinical test battery for all patients aged 60 years and older, comprising low luminance/low contrast (SKILL) VA or low contrast VA, desaturated D-15 colour vision assessment, flicker perimetry, glare recovery and dark adaptation if possible, together with conventional assessments of case history, ophthalmoscopy and high contrast visual acuity (VA) for the detection and diagnosis of ARM. Reading rate is also discussed as a potential indicator of early visual loss. For monitoring the progressive visual loss in age-related macular degeneration (AMD) and determining the requirements for optometric vision rehabilitation, we recommend more conventional clinical vision tests of distance and near visual acuity, reading rate, the effects of varying illumination and a functional central visual field assessment.

Relationship of Sighting Ocular Dominance with Macular Photostress Test Time and Thickness of the Middle Macular Layers

SIGNIFICANCE

The mechanisms of sighting ocular dominance, which is particularly important in monovision therapies and sports vision, are not fully understood yet. Whether the macula affects ocular dominance or ocular dominance affects the macula is also a subject of interest.

PURPOSE

The aim of this study was to investigate the relationship of sighting ocular dominance with macular photostress test time and middle macular layer thickness.

METHODS

One-hundred eyes of 50 healthy adult volunteers were included in this cross-sectional study. Sighting eye dominance was decided by a hole-in-the-card test. The macular photostress test was performed by exposing the eye to the ophthalmoscope light for 10 seconds and measuring the time taken to return to visual acuity within one row of pre-light exposure acuity. The spectral-domain optical coherence tomography examinations were performed to measure thickness of middle macular layers (i.e., outer nuclear, outer plexiform, inner nuclear, and inner plexiform). Refractive error and intraocular pressure (IOP) measurements were also recorded.

RESULTS

The comparison of dominant and nondominant eyes in the aspect of refractive error, IOP, and macular photostress test time did not show statistically significant differences (P > .05). The thicknesses of macular outer nuclear, outer plexiform, inner nuclear, and inner plexiform layers were similar in the dominant and nondominant eyes (P > .05). In addition, macular photostress time was not statistically significantly correlated with the thickness of middle macular layers (P > .05).

CONCLUSIONS

The thickness of middle macular layers and macular photostress recovery time are similar in dominant and nondominant eyes.

Disability glare and nighttime driving performance among commercial drivers in Ghana

OBJECTIVE

Glare caused by the headlights of on-coming vehicles risk safe driving at night. The study aimed to determine the relationship between glare exposure and nighttime driving performance among commercial drivers in Ghana.

METHODS

This cross-sectional study involved commercial drivers with complaints of nighttime driving difficulties (N = 80; mean age = 41.5 ± 11.1 years). A questionnaire was used to investigate nighttime driving performance following glare exposure. We measured contrast sensitivity and visual acuity under photopic conditions. With an experimental setup in a mesopic setting, we measured visual acuity with and without glare exposure. The difference between the two mesopic visual acuities was quantified as disability glare index. With the same setup, photostress recovery time was also measured. Regression analyses were used to determine the relationship between nighttime driving performance score and the measures taken in both photopic and mesopic settings.

RESULTS

The average nighttime driving performance score was 47.8 ± 17.5. Driving performance was negatively correlated with all variables (R = -0.87 to -0.30, all p < .01), except contrast sensitivity (R = 0.74, p < .01). A multiple linear regression showed that the model with all variables explained 83.8% of the variance, but only disability glare index was a significant predictor of nighttime driving performance following glare exposure (standardized B = -0.61, p < .01).

CONCLUSION

Our results show that the change in mesopic visual acuities following glare can predict nighttime driving performance. This measure can be incorporated into the assessment of driving fitness by licensing departments to evaluate whether a person can drive safely at night amidst glare exposure.

Retinal Diseases that Can Masquerade as Neurological Causes of Vision Loss

PURPOSE OF REVIEW

This review aims to discuss retinal diseases that may masquerade as neurological causes of vision loss and highlights modern ophthalmic ancillary testing that can help to establish these diagnoses.

RECENT FINDINGS

Retinal diseases with signs and symptoms overlapping with neurological causes of vision loss include central serous chorioretinopathy, retinal ischemia, acute macular neuroretinopathy, Acute zonal occult outer retinopathy (AZOOR) complex diseases, paraneoplastic retinopathy, retinal dystrophy, and toxic retinopathy. Diagnosis is facilitated by electrophysiologic studies and multimodal ophthalmic imaging including optical coherence tomography and fundus autofluorescence imaging. Looking into the future, translation of adaptive optics ophthalmoscopy into clinical practice may facilitate early detection of microscopic retinal abnormalities that characterize these conditions. With conventional methods of physical examination, diagnosis of retinal diseases that may masquerade as neurological causes of vision loss can be challenging. Current advance in multimodal ophthalmic imaging along with electrophysiologic studies enhances the provider's ability to make early diagnosis and monitor progression of these conditions.

Individual differences in visual function

A significant proportion of research on the visual system focuses on general principles that apply to samples and/or populations. Many questions, however, are more suited to the specific characteristics of an individual. The visual system, like most systems of the body, is extremely variable with respect to function and susceptibility to disease. Understanding this variation is an important avenue to better measurement, disease prevention and treatment.

An Alternative Psychophysical Diagnostic Indicator of the Aging Eye

Purpose

Impaired adaptation to changes in lighting levels as well as mesopic visual function is a common complaint in those over the age of 65. The use of photostress is a well-established method to test the adaption rate and the response of the visual cycle. In this study, we test visual function recovery to mesopic luminance stimuli following a long duration photostress in young and elderly subjects. If successful in strongly differentiating aging macular function, these methods may also be useful in the study of pathologies such as age-related macular degeneration.

Methods

A group of 12 older normal subjects (mean age 75.1 ± 4.79) and a control group of 5 younger normal subjects (mean age 26.2 ± 4.19) were subjected to macular photostress using the OraLux photostress system. The OraLux system provides a diffuse light source bleaching 84% of cone photopigment while maintaining an exposure safety factor of 200 times less than the maximum safe exposure. After each photostressing session, macular recovery was tracked using a foveal, variable contrast, flickering stimulus of mean luminance in the high mesopic range. Recovery was tracked for 300 seconds. The endpoint was time to recovery to each individual's baseline sensitivity as determined by two static sensitivity trials prior to photostress.

Results

Proportional hazards analysis of recovery time yielded a statistically significant difference between the older group and the young group (HR = 0.181; p=0.0289). The estimated hazard ratio of 0.181 indicates that older subjects return to baseline at less than one-fifth the rate of younger subjects. The hazards ratio remained statistically significant after adjusting for visual acuity (HR = 0.093; p=0.0424).

Conclusion

Photostress recovery of flicker sensitivity under mesopic conditions is a strong differentiator of aging macular function. This agrees with subject-reported complaints in reduced luminance conditions after exposure to bright lights such as night driving. The qualitative similarity between the aging retina and changes in early AMD suggests that flicker recovery following photostress may be useful as a surrogate endpoint in AMD clinical trials.

An Investigation of the Role of Macular Pigment in Attenuating Photostress through Comparison between Blue and Green Photostress Recovery Times

PURPOSE

Photostress recovery time (PSRT) is the time required for the macula to return to its normal functioning after the bleaching of cone photopigments due to light exposure, usually white. This work investigates the role of macular pigment (MP) as an optical filter that attenuates photostress by analyses of PSRT at different wavelengths.

METHODS

Thirty-nine subjects (19-28 years) were exposed to blue/green photostress varying in irradiance. During photostress, pupil constriction (C_p) was measured. Twenty-seven subjects (20-27 years) were exposed to white photostress. After 25 s of photostress, the time (PSRT) required to read correctly a 0.2 logMAR letter was measured. Correlation was studied between PSRT, C_P, and irradiance. Statistical significance of differences between PSRTs was evaluated at Log(irradiance(quanta s^-1 cm^-2)) = 14 by Student's t statistics.

RESULTS

C_p and PSRT were found linearly correlated to Log(irradiance) for blue, green, and white. At Log(irradiance(quanta s^-1 cm^-2)) = 14, blue and green mean PSRTs resulted different (p < 0.001) with 3.8 ± 0.8 s and 6.7 ± 1.7 s, respectively. After correcting irradiance for the optical absorption of MP, mean blue PSRT became 6.6 ± 0.8 s, at the logarithm of MP-corrected irradiance in quanta s^-1 cm^-2 equal to 14 (p = 0.571 compared to green PSRT). For white light, at the logarithm of MP-corrected irradiance in quanta s^-1 cm^-2 equal to 14, mean PSRT was 7.5 ± 2.2 s, not significantly different from blue and green PSRT (p > 0.05).

CONCLUSIONS

MP plays the role of an optical filter attenuating photostress. PSRT was substantially proportional to the number of incident photons corrected for the MP optical absorption, regardless of their wavelength.

Photostress Recovery Times in Cases of Central Serous Retinopathy

Photostress recovery times were measured in 50 normal individuals in the age group 20–50 years and in 27 patients who had developed central serous retinopathy. A flash generator of a commercially available fundus camera was used to provide the appropriate stimulus. The results showed that photostress recovery times were grossly abnormal in patients with central serous retinopathy for the first few weeks after the onset of symptoms, but gradually returned to normal values by 5 months and remained so thereafter. In a few patients during the recovery phase a transient paradoxical response was noted, whereby the photostress recovery times became less than in the unaffected control eye.

It appears that the use of a fundus camera to provide photostress stimulus has merit because the light source is subject only to slight variation in intensity, standardization of responses is possible and the technique can be employed on patients about to have fluorescein angiographic studies for diagnostic or documentation purposes.

Neuro-Ophthalmological Emergencies

Neuro-ophthalmological emergencies constitute vision or life-threatening conditions if diagnosis and treatment are not promptly undertaken. Even with immediate therapy, these clinical entities carry a high rate of morbidity. They may present with diplopia, visual loss, and/or anisocoria. Arteritic anterior ischemic optic neuropathy is an ominous condition, which can cause permanent and severe vision loss, stroke, or aortic dissection, requiring immediate steroid therapy. Pituitary apoplexy may go unnoticed if only computed axial tomography is performed. Diseases affecting the cavernous sinus and orbital apex region, such as cavernous sinus thrombosis or mucormycosis, can give rise to simultaneous vision loss and diplopia and, if not treated, may extend to the brain parenchyma causing permanent neurological sequela. An isolated third nerve palsy may be the harbinger of a cerebral aneurysm, carrying a significant risk of mortality. Horner syndrome can be the initial presentation of a carotid dissection, an important cause of stroke in the young adult. The neurohospitalist should be familiar with the workup and management of neuro-ophthalmological emergencies.

Multimodal characterization of proliferative diabetic retinopathy reveals alterations in outer retinal function and structure

PURPOSE

To identify changes in retinal function and structure in persons with proliferative diabetic retinopathy (PDR), including the effects of panretinal photocoagulation (PRP).

DESIGN

Cross-sectional study.

PARTICIPANTS

Thirty adults who underwent PRP for PDR, 15 adults with untreated PDR, and 15 age-matched controls.

METHODS

Contrast sensitivity, frequency doubling perimetry (FDP), Humphrey visual fields, photostress recovery, and dark adaptation were assessed. Fundus photography and macular spectral-domain optical coherence tomography (SD OCT) were performed. To quantify retinal layer thicknesses, SD OCT scans were segmented semiautomatically.

MAIN OUTCOME MEASURES

Visual function measures were compared among patients with PDR and PRP, untreated patients with PDR, and controls. Mean retinal layer thicknesses were compared between groups. Correlation analyses were performed to evaluate associations between visual function measures and retinal layer thicknesses.

RESULTS

A significant reduction of FDP mean deviation (MD) was exhibited in PRP-treated patients with PDR (MD ± standard deviation, -8.20±5.76 dB; P < 0.0001) and untreated patients (-5.48±4.48 dB; P < 0.0001) relative to controls (1.07±2.50 dB). Reduced log contrast sensitivity compared with controls (1.80±0.14) also was observed in both PRP-treated patients (1.42±0.17; P < 0.0001) and untreated patients (1.56±0.20; P = 0.001) with PDR. Compared with controls, patients treated with PRP demonstrated increased photostress recovery time (151.02±104.43 vs. 70.64±47.14 seconds; P = 0.001) and dark adaptation speed (12.80±5.15 vs. 9.74±2.56 minutes; P = 0.022). Patients who underwent PRP had diffusely thickened nerve fiber layers (P = 0.024) and diffusely thinned retinal pigment epithelium (RPE) layers (P = 0.009) versus controls. Untreated patients with PDR also had diffusely thinned RPE layers (P = 0.031) compared with controls.

CONCLUSIONS

Patients with untreated PDR exhibited inner retinal dysfunction, as evidenced by reduced contrast sensitivity and FDP performance, accompanied by alterations in inner and outer retinal structure. Patients who underwent PRP had more profound changes in outer retinal structure and function. Distinguishing the effects of PDR and PRP may guide the development of restorative vision therapies for patients with advanced diabetic retinopathy.

Suitability and repeatability of a photostress recovery test device, the macular degeneration detector (MDD-2), for diabetes and diabetic retinopathy assessment

BACKGROUND

Diabetic retinopathy can result in impaired photostress recovery time despite normal visual acuity and fundoscopic appearance. The Macular Degeneration Detector (MDD-2) is a novel flash photostress recovery time device. In this study, we examine the repeatability of the MDD-2 in normal and diabetic subjects.

METHODS

One hundred and ninety one (90 women, 101 men) subjects were recruited and divided into 1 of the 3 study groups (normal controls, n = 40; diabetes no retinopathy, n = 98; nonproliferative diabetic retinopathy, n = 53). Photostress recovery time was measured three times in the study eye using the MDD-2, each measurement separated by a 5-minute interval.

RESULTS

Repeated measures analysis of variance revealed no statistically significant learning or fatigue effects on intrameasurement repeatability for any group. Photostress recovery time measures were broadly similar and typically not statistically significantly different between study groups. The coefficient of repeatability reached clinically acceptable levels once the initial photostress recovery time measure, which demonstrated increased variability and latency compared with all subsequent measures, was excluded.

CONCLUSION

The MDD-2 seems to provide repeatable photostress recovery time measurements among naive diabetic subjects. The device does not, however, seem capable of differentiating normal and nonproliferative diabetic eyes, and would not be suitable for inclusion in diabetic retinopathy screening protocol.

Clinical applicability of the Macular Degeneration Detection Device (MDD-2): a novel photostress recovery measurement device

BACKGROUND

Diseases affecting the macula, such as age-related macular degeneration (AMD), diabetic retinopathy and central serous retinopathy can result in impaired photostress recovery time (PSRT) despite normal visual acuity and fundoscopic appearance. The MDD-2 Macular Degeneration Detection Device is a novel flash photostress recovery device. In this study, we examine the repeatability of the MDD-2 in a normal population and its suitability for incorporation into routine clinical practice.

METHODS

One hundred (60 female) subjects (mean age 35 ± 8 years; range 18 to 66 years) were recruited to partake in this study. The photostress recovery time was measured using the MDD-2 on three occasions in the dominant eye and one final occasion in the non-dominant eye to assess measurement repeatability. All subjects were in good ocular health. Visual acuity and iris colour were recorded for each participant.

RESULTS

Repeated measures analysis of variance revealed a statistically significant learning effect on intra-measurement repeatability (p < 0.01). Although paired t-test analysis revealed statistically significant differences between repeated measures both within and between eyes (p < 0.05 for all) the correlation between repeat measurements is statistically significant (p < 0.05 for all), and the coefficient of repeatability reaches clinically acceptable levels once the initial photostress recovery time, which demonstrated increased variability and latency compared to all subsequent measures, is excluded.

CONCLUSION

The MDD-2 provides highly repeatable measurements of photostress recovery time among young naïve subjects, following verbal explanation of the task and only one 'practise' measurement. The measurement is also highly repeatable between eyes, providing a potential immediate clinical biomarker of ocular health.

Glare's causes, consequences, and clinical challenges after a century of ophthalmic study

PURPOSE

To provide a multidisciplinary synthesis of scientific information on disability, discomfort, dazzling, and scotomatic (photostress) glare.

DESIGN

Perspective.

METHODS

Analysis and integration of relevant historical and contemporary publications on glare in ophthalmology, illumination engineering, neurology, and other relevant disciplines.

RESULTS

Disability glare is caused by scattered intraocular light (straylight) not useful for vision. Straylight casts a veiling luminance on the retina, reducing image contrast and impairing vision. In common environments, glare and target illumination sources have the same or similar spectra. Colored spectacle or intraocular lens filters reduce both proportionately, so they do not increase retinal image contrast or decrease disability glare. Discomfort glare is caused by situational illumination too intense or variable. Dazzling glare occurs when high illuminances are spread across the retina. Neurophysiological research is clarifying how discomfort and dazzling glare depend on different retinal photoreceptors and nociceptive brain pathways involving the trigeminal ganglion and thalamus. Photostress is caused by excessive local retinal photopigment bleaching uncommon in ordinary situations. Optical glare countermeasures are available for daytime driving but not oncoming automobile headlights at night. Filters that decrease daytime discomfort or dazzling glare also reduce nighttime mesopic and scotopic sensitivity.

CONCLUSIONS

Glare is problematic for patients and clinicians despite a century of scientific research. Advances in understanding glare have been hampered by its complex, multidisciplinary nature and limited interdisciplinary communication. We provide one pathway through the forest of glare nomenclature and mechanisms. Improved diagnostic and therapeutic methodologies await continuing progress in understanding glare.

Retinal disorders

The retina represents part of the central nervous system (CNS). After modifying the neural signal, the axon of the last neuron enters the optic nerve and leaves the eye. In most cases of retinal disease leading to visual loss, the diagnosis will be made by an ophthalmologist after examining the ocular fundus. Some retinal disorders, however, might not be detectable at the time of examination. Those patients will be referred to a neurologist for "unexplained visual loss" when suspecting a lesion behind the optic nerve. Moreover, knowledge of potential retinal abnormalities is useful for the neurologist when seeing patients with CNS disease, which can manifest itself also in the retina. This chapter aims to give an overview about retinal disorders causing no or only few retinal abnormalities, those associated with neurological diseases, as well as the most important retinal diseases involving the tissues of the ocular fundus (vitreous body, retina, pigment epithelium, and the choroid). The most frequently used examination techniques and diagnostic tools are described. Tumors, vascular disease, especially diabetic retinopathy, age-related macular degeneration, chorioretinal inflammatory and toxic disorders, paraneoplastic retinopathies, inherited retinal dystrophies, and retinal involvement in CNS disease such as phakomatoses and multiple sclerosis are discussed.

Transient monocular visual loss

Transient monocular visual loss is an important clinical complaint and has a number of causes, of which the most common is retinal ischemia. A practical approach is to perform a careful examination to determine whether there are any eye abnormalities that can explain the visual loss. Despite the transient nature of the symptom, there may be clues to the diagnosis on the examination even after the visual loss has recovered.

Functional outcome of subthreshold versus threshold diode laser photocoagulation in diabetic macular oedema

AIMS

To compare the efficacy of subthreshold diode laser photocoagulation with conventional threshold diode laser in clinically significant macular oedema (CSME) in diabetics.

METHODS

Prospective randomised controlled trial. Thirty eyes of 20 patients with CSME having central macular thickness (CMT) >or=250 microm on optical coherence tomography (OCT) and best corrected Snellen visual acuity (BCVA) of 20/80 or better were randomly assigned to receive subthreshold diode laser (group A) or threshold laser (group B). The clinical course of BCVA, CMT on OCT, photo stress recovery time (PSRT), contrast sensitivity (CS) using Pelli Robson chart, and central visual field (10-2 VF, Humphrey Field Analyser II) were monitored regularly for 18 weeks after intervention.

RESULTS

Both groups showed significant (P=0.03) and comparable improvement in mean BCVA at 18 weeks visit. There were also significant and comparable reductions (P<0.01) in mean CMT at all visits compared with baseline in both groups. PSRT and CS (75+/-16 (mean+/-SD) and 0.72+/-0.3 in group A and 81+/-12 and 0.68+/-0.2 in group B pre-laser) were significantly better in group A at the final visit (66+/-17 and 1.04+/-0.3) as compared to group B (78+/-11 and 0.73+/-0.3). One patient in group B showed a paracentral scotoma on 10-2 VF after the laser, which persisted till the end of follow-up.

CONCLUSION

Subthreshold diode laser photocoagulation is as effective as conventional threshold laser in reducing or eliminating diabetic macular oedema (on OCT) and in improving BCVA. Recovery of macular function as assessed by CS and PSRT maybe better with subthreshold laser.

Reproducible measurement of macular light flash recovery time using a novel device can indicate the presence and worsening of macular diseases

PURPOSE

To determine the safety, sensitivity, and specificity of a novel flash photorecovery timing instrument with response verification in differentiating normal from abnormal maculae, and in detecting worsening macular disease.

METHODS

Right and left eye photorecovery times were determined at baseline and after 5 min using a xenon arc, flash filtered for infrared, ultraviolet, and visible short wavelengths, delivered through an aperture in a hand-held tube. A push-button actuated timer and flash and stopped timer when lighted numbers became visible post-flash. A numeric keypad verified responses. Normal subjects (two eyes tested, n = 144; one eye tested, n = 108) ranged in age from 15 to 84. Photorecovery times were measured in one eye of subjects with small drusen and 20/20 acuity (53-55 correct ETDRS letters; n = 57); in both eyes of subjects with dry age-related macular degeneration (AMD; n = 118); wet AMD with (n = 19) or without (n = 17) macular fluid; and eyes of diabetics with background retinopathy with (n = 19) or without (n = 17) macular retinal thickening. Once-weekly photorecovery measurements for 6 months in each eye of 10 dry AMD subjects and 10 dry diabetic maculopathy subjects provided longitudinal data.

RESULTS

Normal subjects' mean right eye recovery time was 9.6 sec (+/- 1.9 SD); left 10.8 sec (+/- 1.0 SD). Photorecovery lengthened after age 55, nearly doubling that of young subjects by age 80. Macular edema, serous macular detachment, or worsened dry AMD were accompanied by prolonged photorecovery (p < .01). When abnormal new vessels or retinal thickening appeared in three serially followed patients, photorecovery at least doubled (p < .01). In all three, photorecovery prolongation occurred without clinical symptoms. None of the 499 tested subjects reported adverse events due to the flash testing.

CONCLUSIONS

These findings support the usefulness of a reproducible light flash macular vision recovery measurement as an indicator of macular pathology and worsening disease.

The macular automated photostress test

PURPOSE

To introduce a standardized macular photostress test using an automated perimeter as a method to quantify macular disease severity and as a tool to distinguish optic neuropathy from macular pathology.

DESIGN

Prospective interventional pilot study.

METHODS

Twenty-five bilaterally pseudophakic subjects aged range, 65 to 84: 15 patients with varying severity of non-neovascular age-related macular degeneration (AMD), five patients with no ocular disease, and five patients with moderate primary open-angle glaucoma (POAG). Previously reported normative values served as controls for this study. Patients underwent foveal threshold testing using the Humphrey Visual Field Perimeter Model 750 (Carl Zeiss Meditec, Inc, Dublin, California, USA). Baseline measurements were compared to threshold sensitivity after photostress at one minute and then two-minute intervals until sensitivity returned to baseline. Main outcome measures were baseline foveal threshold sensitivity, foveal threshold depression, and recovery following photostress.

RESULTS

Automated macular photostress testing in macular disease (AMD) causes a decrease (P < .001) in baseline foveal sensitivity and a delay (P < .001) in recovery time to baseline sensitivity. Optic nerve pathology (POAG) does not affect (P = .343) the foveal response curve.

CONCLUSIONS

The macular automated photostress (MAP) test is an inexpensive, noninvasive, and readily accessible adjunct for evaluating patients with macular disease. This standardized protocol is useful in objectively defining disease severity, may be used to follow response to treatment, and could aid in distinguishing optic neuropathy from macular pathology.

Principles of modern low vision rehabilitation

Low vision rehabilitation is a new emerging subspecialty drawing from the traditional fields of ophthalmology, optometry, occupational therapy, and sociology, with an ever-increasing impact on our customary concepts of research, education, and services for the visually impaired patient. A multidisciplinary approach and coordinated effort are necessary to take advantage of new scientific advances and achieve optimal results for the patient. Accordingly, the intent of this paper is to outline the principles and details of a modern low vision rehabilitation service. All rehabilitation attempts must start with a first hand interview (the intake) for assessing functionality and priority tasks for rehabilitation, as well as assessing the patient's all-important cognitive skills. The assessment of residual visual functions follows the intake and offers a unique opportunity to measure, evaluate, and document accurately the extent of functional loss sustained by the patient from disease. An accurate assessment of residual visual functions includes assessment of visual acuity, contrast sensitivity, binocularity, refractive errors, perimetry, oculomotor functions, cortical visual integration, and light characteristics affecting visual functions. Functional vision assessment in low vision rehabilitation measures how well one uses residual visual functions to perform routine tasks, using different items under various conditions, throughout the day. Of the many functional vision skills known, reading skills is an obligatory item for all low vision rehabilitation assessments. Results of assessment guide rehabilitation professionals in developing rehabilitation plans for the individual and recommending appropriate low vision devices. The outcome from assessing residual visual functions is detection of visual functions that can be improved with the use of optical devices. Methods for prescribing devices such as image relocation with prisms to a preferred retinal locus, field displacement to primary gaze position, field expansion, and manipulation of light are practiced today in addition to, or instead of, magnification. Correction of refractive errors, occlusion therapy, enhancement of oculomotor skills, and field restitution are additional methods now available for prescribing devices leading to rehabilitation of visual functions. The outcome from assessing residual functional vision is detection of functional vision that can be improved with the use of vision therapy training. After restoration of optimal residual visual functions is achieved with optical devices, one can follow with training programs for restoration of lost vision-related skills. If an optical dispensary is available where prescribing of low vision devices routinely take place, this will help ensure familiarity and specialization of the dispensary and staff with low vision devices and their special dispensing requirements. The dispensing of low vision devices is an opportunity to introduce the device to the patient, train the patient in the correct use of the device for the task selected, and create a direct and continuous connection with the patient until the next encounter. Following assessment, prescribing, and dispensing of devices, a low vision practitioner, ophthalmologist or optometrist, is responsible for recommending and prescribing vision therapy training to improve residual functional vision. An attempt to present a template for a comprehensive modern low vision rehabilitation practice is made here by summarizing scientific developments in the field and stressing the multidisciplinary involvement required for this kind of practice. It is hoped that this paper and other initiatives from colleagues, the public, and government will promote and raise awareness of modern low vision rehabilitation for the benefit of all.

Visual function and dysfunction in early and late age-related maculopathy

Late age-related maculopathy (ARM) is responsible for the majority of blind registrations in the Western world among persons over 50 years of age. It has devastating effects on quality of life and independence and is becoming a major public health concern. Current treatment options are limited and most aim to slow progression rather than restore vision; therefore, early detection to identify those patients most suitable for these interventions is essential. In this work, we review the literature encompassing the investigation of visual function in ARM in order to highlight those visual function parameters which are affected very early in the disease process. We pay particular attention to measures of acuity, contrast sensitivity (CS), cone function, electrophysiology, visual adaptation, central visual field sensitivity and metamorphopsia. We also consider the impact of bilateral late ARM on visual function as well as the relationship between measures of vision function and self-reported visual functioning. Much interest has centred on the identification of functional changes which may predict progression to neovascular disease; therefore, we outline the longitudinal studies, which to date have reported dark-adaptation time, short-wavelength cone sensitivity, colour-match area effect, dark-adapted foveal sensitivity, foveal flicker sensitivity, slow recovery from glare and slower foveal electroretinogram implicit time as functional risk factors for the development of neovascular disease. Despite progress in this area, we emphasise the need for longitudinal studies designed in light of developments in disease classification and retinal imaging, which would ensure the correct classification of cases and controls, and provide increased understanding of the natural course and progression of the disease and further elucidate the structure-function relationships in this devastating disorder.

Effect of age related macular degeneration on the Eger macular stressometer photostress recovery time

AIM

To assess the repeatability of Eger macular stressometer (EMS) measures of photostress recovery and determine their association with other measures of visual function.

METHODS

EMS photostress recovery time was measured in 90 patients with bilateral exudative age related macular degeneration (AMD), 19 with bilateral atrophic AMD and 47 with both forms of the condition (mean age 79 (SD 13) years). Measurements were made on two occasions separated by 1 year. Intrasession repeatability was assessed by repeating the measures after a 10 minute recovery period at the first visit. Distance visual acuity was measured with a logMAR chart, near visual acuity with a MNRead chart at 25 cm, contrast sensitivity with a Pelli-Robson chart, and the presence of central visual disturbance assessed with an Amsler grid. A questionnaire was used to assess self reported difficulties with glare recovery.

RESULTS

The average EMS recovery time was 11.0 (SD 8.9) seconds, decreasing by 1.6 (5.2) seconds on repeated measurement (p<0.05). EMS photostress recovery was not correlated with visual function measures or subjective difficulties with lights (p>0.05). EMS photostress recovery time did not predict those whose vision decreased over the following year compared with those among whom it remained stable.

CONCLUSIONS

The EMS test is not a useful tool in determining the severity or progression of AMD.

Evaluation of retinal function using the Dynamic Focal Cone ERG

The development of effective means of assessing visual function in retinal disease holds the key to improved understanding of pathogenesis, and better monitoring of treatment outcomes. In diseases such as age-related macular degeneration, in which the primary locus of dysfunction is the outer retina, tests which provide a direct measure of the functional integrity of the photoreceptor/retinal pigment epithelium (RPE) complex are of great importance. Recovery of retinal function following adaptation to a bright light requires the healthy function of photoreceptors, RPE, Bruch's membrane and choroidal circulation, making an assessment of this recovery a potentially useful clinical tool. However, current techniques are either subjective in nature, or are influenced by post-retinal processing of visual information. This report describes a novel technique, the 'Dynamic Focal Cone Electro-retinogram (ERG)', which allows direct, objective assessment of the recovery of macular function following photopigment bleach. A series of 41 Hz ERGs was recorded, and ERG amplitude was plotted as a function of time following cessation of the bleach. Normative data was collected from 10 healthy subjects. For all subjects, there was no measurable ERG immediately after the bleach, but the amplitude had returned to a pre-bleach level within 4 min. The amplitude recovery data were adequately described both by an exponential recovery function and by a model based on a rate-limited recovery process. We conclude that this technique provides a clinically applicable, objective measure of outer retinal recovery.

Protective effects of oral antioxidants on skin and eye function

BACKGROUND

Antioxidants applied topically and/or taken systemically may play an important role in counteracting the oxidative injury to lipids and proteins on the skin and eye that are provoked by radical oxygen species.

OBJECTIVE

The aim of the study was to control photoprotective activity of the skin and eye through the use of oral antioxidants in 50 smoker volunteers (10 cigarettes/d) aged between 25-36 years and affected by dry skin.

METHODS

Oxidative stress was assessed by a randomized double-blind study, and the ROS-Meter System (Dermotech, Rome, Italy). Global visual function was determined by the use of different visual surveillance tests.

RESULTS

A 40% decrease of oxidative stress in blood serum was verified, with a clear relationship between global visual function and the oral intake of an oxygenated carotenoid (lutein).

CONCLUSIONS

Carotenoids used as nutritional supplements seem to play an interesting photoprotective role for both skin and eyes, eventually increasing the activity of topical sunscreens.

MACULAR PHOTOSTRESS TESTING: SENSITIVITY AND RECOVERY WITH AN AUTOMATED PERIMETER

PURPOSE

To describe a novel method for the evaluation of macular function with photostress testing and outline normative foveal threshold and recovery data for the adult population.

METHODS

In this prospective study, 50 adult subjects (25 men and 25 women aged 30-49 years) with no ocular disease underwent foveal threshold testing using the Humphrey Visual Field Perimeter Model 750. Baseline values and recovery time after photostress were measured. Baseline measurements were compared with threshold sensitivity after photostress at 1, 2, 4, 6, and 10 minutes.

RESULTS

Mean foveal sensitivities were reduced from 38.53 db to 32.36 db after photostress, representing an average sensitivity reduction of 16%. The mean recovery time to baseline sensitivity was 6.58 minutes. There was no significant difference between sexes, races, or smokers and nonsmokers.

CONCLUSIONS

This standardized protocol for testing the foveal threshold response to photostress is an inexpensive and noninvasive adjunct for following macular disease and also distinguishing optic neuropathy from macular disease.

Reliability, normative data, and the effect of age-related macular disease on the Eger Macular Stressometer photostress recovery time

PURPOSE

To assess repeatability and reproducibility, to determine normative data, and to investigate the effect of age-related macular disease, compared with normals, on photostress recovery time measured using the Eger Macular Stressometer (EMS).

METHOD

The study population comprised 49 healthy eyes of 49 participants. Four EMS measurements were taken in two sessions separated by 1 h by two practitioners, with reversal of order in the second session. EMS readings were also taken from 17 age-related maculopathy (ARM), and 12 age-related macular degeneration (AMD), affected eyes.

RESULTS

EMS readings are repeatable to within +/-7 s. There is a statistically significant difference between controls and ARM affected eyes (t = 2.169, p = 0.045), and AMD affected eyes (t = 2.817, p = 0.016). The EMS is highly specific, and demonstrates sensitivity of 29% for ARM, and 50% for AMD.

CONCLUSIONS

The EMS may be a useful screening test for ARM, however, direct illumination of the macula of greater intensity and longer duration may yield less variable results.

Double-masked, placebo-controlled, randomized trial of lutein and antioxidant supplementation in the intervention of atrophic age-related macular degeneration: the Veterans LAST study (Lutein Antioxidant Supplementation Trial)

BACKGROUND

Age-related macular degeneration (ARMD) is the leading cause of vision loss in aging Westem societies. The objective of the lutein antioxidant supplementation trial (LAST) is to determine whether nutritional supplementation with lutein or lutein together with antioxidants, vitamins, and minerals, improves visual function and symptoms in atrophic ARMD.

METHODS

The study was a prospective, 12-month, randomized, double-masked, placebo-controlled trial conducted at an urban midwestern Veterans Administration Hospital from August 1999 to May 2001. Ninety patients with atrophic ARMD were referred by ophthalmologists at two Chicago-area veterans medical facilities. Patients in Group 1 received lutein 10 mg (L); in Group 2, a lutein 10 mg/antioxidants/vitamins and minerals broad spectrum supplementation formula (L/A); and in Group 3, a maltodextrin placebo (P) over 12 months.

RESULTS

In Groups 1 L and 2 L/A, mean eye macular pigment optical density increased approximately 0.09 log units from baseline, Snellen equivalent visual acuity improved 5.4 letters for Group 1 L and 3.5 letters for Group 2 L/A, and contrast sensitivity improved. There was a net subjective improvement in Amsler grid in Group 1 L. VFO-14 questionnaires conceming subjective glare recovery were nearly significant at 4 months for Group 2 L/A. Patients who received the placebo (Group 3) had no significant changes in any of the measured findings.

CONCLUSION

In this study, visual function is improved with lutein alone or lutein together with other nutrients. Further studies are needed with more patients, of both genders, and for longer periods of time to assess long-term effects of lutein or lutein together with a broad spectrum of antioxidants, vitamins, and minerals in the treatment of atrophic age-related macular degeneration.

The Eger Macular Stressometer: pilot study

PURPOSE

To evaluate the sensitivity of the Eger Macular Stressometer (EMS) for early screening of age-related macular degeneration (AMD) in a clinical practice. We examined the null hypothesis that AMD eyes have EMS recovery times (RTs) that do not differ from eyes with cataract, diabetic retinopathy, or glaucoma.

DESIGN

The design of this study was a nonrandomized clinical trial.

METHODS

Ninety-two eyes from 92 patients with vision 20/80 or better, age 50 and older, of either gender, and any ethnic origin, were recruited into one of four groups: AMD (30 eyes), normal or mild cataract (30 eyes), diabetic retinopathy (16 eyes), and glaucoma (16 eyes). Recovery times were obtained with the EMS, according to manufacturer's instructions.

RESULTS

The mean (SD) [median] RT for the AMD group was 11.8 (7.6) [9] seconds, the normal/cataract group 10.0 (4.3) [9] seconds, the diabetic retinopathy group 8.4 (3.0) [8] seconds, and glaucoma group 8.6 (2.4) [8] seconds. Recovery time did not appear to be related to group (P =.58), age (P =.50), visual acuity (P =.52), or sex (P =.23).

CONCLUSIONS

We found EMS RT distributions did not differ between AMD, cataract, diabetic retinopathy, and glaucoma groups. The EMS in its current form is not a sensitive screening tool for AMD. Further testing is needed to examine EMS sensitivity with other macular diseases such as central serous choroidopathy and diabetic macular edema.

Visual dysfunction in retinal and optic nerve disease

Visual perceptions seen with retinal and optic nerve disease may overlap with those resulting from retrochiasmal disorders. A few disorders typically present with distinctive perceptions, but the majority have less specific symptoms. Features include whether or not the visual phenomena are negative or positive, monocular or binocular, and the location and form of any deficits. Among negative phenomena, transient visual loss usually is the result of ischemic disease, but particular precipitants may suggest demyelination or photoreceptor degeneration. The pattern and location of visual field defects may help localize disorders to the level of the macula, papillomacular or other inner retina nerve fiber bundles, optic nerve, or chiasm. Altered brightness perception may point to optic nerve or photoreceptor disease. Decreased acuity is among the most common and least specific symptoms, but association with other symptoms may help to narrow the differential diagnosis. Dyschromatopsia points to either a photoreceptor or optic nerve pathologic condition (Table 7). Among positive phenomena, hallucinations resulting from anterior visual system disorders typically are unformed, although deafferentation of retrochiasmal pathways may produce formed hallucinations. The common "floaters" frequently are benign, but occasionally herald more concerning disorders. Various types of photopsias commonly occur with vitreal disorders or photoreceptor disorders. Macular disease typically leads to distortions of the central visual field, and other particular disorders lead to a host of characteristic distortions of color, form, or brightness. Careful attention to the ophthalmologic examination, visual fields, and subtle variance in symptomatology also help to distinguish among various disorders.

Why HID headlights bother older drivers

Driving requires effective coordination of visual, motor, and cognitive skills. Visual skills are pushed to their limit at night by decreased illumination and by disabling glare from oncoming headlights. High intensity discharge (HID) headlamps project light farther down roads, improving their owner's driving safety by increasing the time available for reaction to potential problems. Glare is proportional to headlamp brightness, however, so increasing headlamp brightness also increases potential glare for oncoming drivers, particularly on curving two lane roads. This problem is worse for older drivers because of their increased intraocular light scattering, glare sensitivity, and photostress recovery time. An analysis of automobile headlights, intraocular stray light, glare, and night driving shows that brightness rather than blueness is the primary reason for the visual problems that HID headlights can cause for older drivers who confront them. The increased light projected by HID headlights is potentially valuable, but serious questions remain regarding how and where it should be projected.

A double-blind placebo-controlled evaluation of the acute effects of sildenafil citrate (Viagra) on visual function in subjects with early-stage age-related macular degeneration

PURPOSE

To assess the effects of a single 100-mg dose of sildenafil citrate on visual function in men with early-stage age-related macular degeneration.

DESIGN

Randomized double-blind placebo-controlled clinical trial.

METHODS

Nine men (mean age 71 years, range 59-85 years) with early-stage (minimal visual impairment and large drusen in the macula) age-related macular degeneration and 20/40 or better-corrected visual acuity in at least one eye were prospectively randomized to receive either placebo or sildenafil citrate (Viagra; Pfizer Inc, New York, New York) 100 mg as a single oral dose. After 7-14 days, they received the alternate treatment. Subjects underwent visual acuity, Amsler grid, color discrimination (D15), traffic light, Humphrey perimetry, and photo-stress testing in each eye before and at specific intervals within 8 hours after dosing.

RESULTS

Compared with placebo, no pattern of errors were evident in any visual function test following sildenafil administration. No statistically or clinically relevant changes from baseline were observed in visual acuity, Humphrey perimetry (corrected pattern standard deviation), D15 color discrimination, or photo-stress tests. No clinically relevant changes were observed in the Amsler grid or traffic light tests. Sildenafil treatment was associated with transient mild or moderate headache, flushing, and rhinitis. There were no visual adverse events spontaneously reported to the investigator.

CONCLUSION

A single 100-mg dose of sildenafil was well tolerated and produced no acute visual effects or exacerbation of preexisting visual impairment in nine men with early-stage age-related macular degeneration.

Sources of variability in the clinical photostress test

The photostress test is a simple clinical technique that can differentiate between retinal and postretinal disease. Unfortunately a wide range of normal results have been reported in the literature and it is perhaps for this reason that the test has been little used by clinicians. The purpose of this investigation was to evaluate the effect of photostress technique, age, ametropia, pupil size and acuity on photostress recovery time (PSRT) in normal subjects. Photostress recovery time was measured in 50 healthy subjects whose ages ranged from 21 to 69 using three clinically applicable techniques and a reference technique designed to bleach a consistent amount of photopigment. The agreement between each clinical technique and the reference technique was determined. Mean photostress recovery time differed for each of the techniques studied. Analysis of the data obtained with the reference and the best clinical technique showed that age was the only factor that had a significant effect on PSRT. The best clinical technique involves exposing the eye to the light from the direct ophthalmoscope for 30 s and measuring the time taken for acuity to return to within one line of pre-bleach acuity. Photostress recovery time increases with age but is independent of pupil size, ametropia and visual acuity.

Contrast and glare sensitivity in epilepsy patients treated with vigabatrin or carbamazepine monotherapy compared with healthy volunteers

BACKGROUND/AIM

Many antiepileptic drugs have influence on visual functions. The aim of this study was to investigate possible changes in contrast sensitivity, macular photostress, and brightness acuity (glare) tests in patients with epilepsy undergoing vigabatrin (VGB) or carbamazepine (CBZ) monotherapy compared with healthy volunteers.

METHODS

32 patients undergoing VGB therapy, 18 patients undergoing CBZ therapy, and 35 healthy volunteers were asked to participate in an ophthalmological examination. In the previous study, visual field constrictions were reported in 40% of the patients treated with VGB monotherapy. In the present study, these VGB and CBZ monotherapy patients were examined for photopic contrast sensitivity with the Pelli-Robson letter chart and brightness acuity and macular photostress with the Mentor BAT brightness acuity tester.

RESULTS

Contrast sensitivity with the Pelli-Robson letter chart showed no difference between these groups and normal subjects (ANOVA: p= 0.534 in the right eye, p= 0.692 in the left eye) but the VGB therapy patients showed a positive correlation between the contrast sensitivity values and the extents of the visual fields in linear regression (R = 0.498, p = 0.05 in the right eye, R = 0.476, p = 0. 06 in the left eye). Macular photostress and glare tests were equal in both groups and did not differ from normal values.

CONCLUSION

The results of this study indicate that carbamazepine therapy has no effect on contrast sensitivity. Vigabatrin seems to impair contrast sensitivity in those patients who have concentrically constricted in their visual fields. Neither GBZ nor VGB affect glare sensitivity.

Visual functions of drivers involved in traffic accidents

Eye functions were studied in 56 drivers who had recently been involved in traffic accidents. There were 17 women and 39 men in the study group, aged 20-87 years. The traffic accidents had happened in intersections and city streets, in parking places and on highways. In seven drivers, a visual impairment was found: two drivers had strabismus and low visual acuities in one or both eyes, two had considerable hyperphoria, and three had a deutan color vision defect. However, comparing the type of accident to the defective eye functions showed no probable correlation.

Extrafoveal photostress recovery test in glaucoma and idiopathic central serous chorioretinopathy

BACKGROUND/AIMS

A photostress recovery test was designed to differentiate macular diseases from optic nerve disorders, but recently an abnormal recovery time was reported in glaucoma. The purpose of this study was to search for the difference in abnormality of the photostress recovery test between glaucoma and idiopathic central serous chorioretinopathy (ICSC).

METHODS

This study involved 21 normal subjects, 14 patients, with ICSC and 10 patients with primary open angle glaucoma (POAG). A scanning laser ophthalmoscope (SLO) was used with microperimetry for bleaching the test point and measuring the recovery of sensitivity. Photostress recovery time (SLO-PSRT) could be measured at extrafoveal points outside and inside the affected area. The initial sensitivity change and the time constant of recovery after bleaching were calculated by fitting an exponential equation to the data.

RESULTS

In normal subjects, neither the initial sensitivity change nor the time constant were correlated with the location of the test point. In 14 patients with ICSC, the initial sensitivity change in the detached area was significantly smaller than that in the unaffected area which was not significantly different from that in the age matched normal subjects. The time constant in the detached area was significantly longer than that in the unaffected area, which was not significantly different from that in the normal subjects. In 10 patients with POAG, the initial sensitivity change inside and outside the scotoma was not significantly different from that of age matched normal subjects. The time constant inside the scotoma was significantly longer than that outside the scotoma, which was not significantly different from that of the age matched normal subjects.

CONCLUSION

Both ICSC and POAG showed a prolonged time constant of recovery, but the initial sensitivity change was reduced only in ICSC. The difference in our results between ICSC and POAG may be caused by the difference of the retinal pathology. Further, the SLO-PSRT is very useful when the lesion is located outside the fovea.

High-risk characteristics of fellow eyes of patients with unilateral neovascular age-related macular degeneration

OBJECTIVE

This study aimed to determine whether clinical tests of ocular function and macular appearance independently can help to predict which patients with unilateral neovascular age-related macular degeneration (AMD) will have a choroidal neovascular membrane (CNVM) develop in their fellow eye.

DESIGN

The study design was a prospective cohort study.

PARTICIPANTS

One hundred twenty-seven patients with unilateral neovascular AMD observed for up to 4.5 years participated.

INTERVENTION

Functional measurements included visual acuity, macular visual field, glare recovery time, and foveal electroretinogram amplitude and implicit time.

MAIN OUTCOME MEASURE

The age-adjusted proportion of patients having a CNVM develop over follow-up assessed by the Cox proportional hazards model with stepwise selection was measured.

RESULTS

On average, 8.8% of patients had a CNVM develop each year. Independent risk factors for the fellow eye were its glare recovery time in minutes (relative risk = 1.30, confidence interval = 1.10-1.54, P = 0.003) and its extent of visible macular abnormalities on a four-point scale (relative risk = 1.62, confidence interval = 1.06-2.59, P = 0.03). Of the fellow eyes that converted, the interval to have a CNVM develop was inversely related to the foveal electroretinogram implicit time.

CONCLUSIONS

A slower recovery from glare and more extensive funduscopic changes appear to be independent risk factors for the development of a CNVM in the fellow eyes of patients with unilateral neovascular AMD. A slower foveal electroretinogram implicit time may be a sign of early stage CNVM development, perhaps because of outer retinal ischemia. These results have clinical management implications, particularly for those patients at high risk of having a potentially treatable form of AMD develop.

Acute unilateral visual loss in the elderly due to retrobulbar optic neuropathy

A 61-year-old man developed fever and a urinary tract infection followed five days later by acute visual loss in the right eye. Funduscopic examination was normal. A retrobulbar optic neuropathy was diagnosed but careful consideration was given to choroidal ischemia as an etiology. A sphenoidal mucocele was found on emergent MRI scan and drained expeditiously, with marked improvement in visual function. The diagnosis of giant cell arteritis should always be entertained when dealing with visual loss in the elderly.

Effect of carotid endarterectomy on the ocular circulation and on ocular symptoms unrelated to emboli

OBJECTIVE

To evaluate haemodynamic changes in the ophthalmic artery and the retina following carotid endarterectomy and their effect on the pathophysiology of the eye.

DESIGN

Prospective study.

METHOD

Twenty-two consecutive patients with severe carotid stenosis underwent 23 carotid endarterectomies and one subclavian-carotid bypass. The following measurements were made preoperatively and 3 months after operation; Ophthalmic artery (OA) and retinal arteriole (RA) peak systolic velocity (PSV) and peak diastolic velocity (PDV), macular photostress recovery time, visual acuity, intraocular pressures, colour vision and visual fields testing.

RESULT

The RA PSV increased by 50% (p = 0.005) and PDV increased by 22% (p = 0.03). The OA PSV increased by 51% (p = 0.001). Macular photostress testing decreased from 58 s to 42 s (p = 0.001). Visual acuity improved in four and was unchanged in 13 eyes ipsilateral to the endarterectomy which had abnormal preoperative measurements. One patient experienced a dramatic increase in the ipsilateral intraocular pressure associated with visual deterioration. In two patients there was resolution of periorbital pain.

CONCLUSION

Our results demonstrate an increase in the PSV of the RA and OA following carotid surgery. There are pathophysiological changes in the eye, which accompany tight stenotic extracranial carotid artery disease and these may be influenced by carotid endarterectomy.