Retinal dysfunction in central serous retinopathy

Photoreceptor Function and Structure in Autosomal Dominant Vitelliform Macular Dystrophy Caused by BEST1 Mutations

Purpose

The purpose of this study was to evaluate rod and cone function and outer retinal structure within macular lesions, and surrounding extralesional areas of patients with autosomal dominant Best vitelliform macular dystrophy caused by BEST1 mutations.

Methods

Seventeen patients from seven families were examined with dark- and light-adapted chromatic perimetry and optical coherence tomography. Subsets of patients had long-term follow-up (14-22 years, n = 6) and dark-adaptation kinetics measured (n = 5).

Results

Within central lesions with large serous retinal detachments, rod sensitivity was severely reduced but visual acuity and cone sensitivity were relatively retained. In surrounding extralesional areas, there was a mild but detectable widening of the subretinal space in some patients and some retinal areas. Available evidence was consistent with subretinal widening causing slower dark-adaptation kinetics. Over long-term follow-up, some eyes showed formation of de novo satellite lesions at retinal locations that years previously demonstrated subretinal widening. A subclinical abnormality consisting of a retina-wide mild thickening of the outer nuclear layer was evident in many patients and thickening increased in the subset of patients with long-term follow-up.

Conclusions

Outcome measures for future clinical trials should include evaluations of rod sensitivity within central lesions and quantitative measures of outer retinal structure in normal-appearing regions surrounding the lesions.

Estimation of current and post-treatment retinal function in chronic central serous chorioretinopathy using artificial intelligence

Refined understanding of the association of retinal microstructure with current and future (post-treatment) function in chronic central serous chorioretinopathy (cCSC) may help to identify patients that would benefit most from treatment. In this post-hoc analysis of data from the prospective, randomized PLACE trial (NCT01797861), we aimed to determine the accuracy of AI-based inference of retinal function from retinal morphology in cCSC. Longitudinal spectral-domain optical coherence tomography (SD-OCT) data from 57 eyes of 57 patients from baseline, week 6-8 and month 7-8 post-treatment were segmented using deep-learning software. Fundus-controlled perimetry data were aligned to the SD-OCT data to extract layer thickness and reflectivity values for each test point. Point-wise retinal sensitivity could be inferred with a (leave-one-out) cross-validated mean absolute error (MAE) [95% CI] of 2.93 dB [2.40-3.46] (scenario 1) using random forest regression. With addition of patient-specific baseline data (scenario 2), retinal sensitivity at remaining follow-up visits was estimated even more accurately with a MAE of 1.07 dB [1.06-1.08]. In scenario 3, month 7-8 post-treatment retinal sensitivity was predicted from baseline SD-OCT data with a MAE of 3.38 dB [2.82-3.94]. Our study shows that localized retinal sensitivity can be inferred from retinal structure in cCSC using machine-learning. Especially, prediction of month 7-8 post-treatment sensitivity with consideration of the treatment as explanatory variable constitutes an important step toward personalized treatment decisions in cCSC.

Central Serous Chorioretinopathy - an Overview

Central serous chorioretinopathy (CSCR) is characterised by retinal serous detachment usually localised in the macular region. CSCR predominantly affects men between 30 and 50 years of age. Traditional classification differentiates between acute (duration shorter than 4 to 6 months) and chronic disease (duration longer than 4 to 6 months). The pathogenesis is multifactorial and current thinking assumes the presence of localised choroidal hyperpermeability with subsequent secondary changes in the retinal pigment epithelium (RPE). The symptoms of acute CSCR include central blurred vision, often with deterioration in visual acuity. Optical coherence tomography (OCT) reveals subretinal fluid (SRF) and/or single retinal pigment epithelial detachments. Fluorescein angiography (FA) usually shows a leaking point with absent or only minor RPE changes in the acute phase and indocyanine green angiography (ICG) highlights circumscribed areas of thickened and hyperpermeable choroid. Acute cases may show spontaneous resolution of SRF, but may also recur and/or become chronic. After the initial diagnosis, spontaneous remission is seen in about 70 to 80% of cases, with a recurrence rate of about 50%. Due to the favourable spontaneous course, it is recommended to wait for 4 to 6 months after the first symptoms manifest. Steroid therapy is considered as a major risk factor. Chronic cases are characterised by slow deterioration in visual acuity with reduced contrast and colour perception. There are extensive RPE changes, with secondary degenerative changes of the photoreceptors. The disease can by complicated by choroidal neovascularisation (CNV), especially in elderly patients. The literature lists a number of treatments: The leakage point (visible in the FA) can be treated by focal laser therapy, either micropulse laser or, if sufficiently distant from the fovea, by argon laser coagulation. Randomised trials in chronic CSCR demonstrated good outcomes with photodynamic therapy. With observation periods ranging from 3 to 6 months, several case series reports found improvement after systemic administration of mineralocorticoid receptor antagonists, carbonic anhydrase inhibitors or non-steroidal anti-inflammatory drugs. In the presence of secondary CNV, anti-VEGF treatment should be initiated. It is unclear whether the combination with PDT might be useful.

Delayed dark adaptation in central serous chorioretinopathy

Purpose

To evaluate the effect of central serous chorioretinopathy (CSCR) on retinal function using dark adaptation in a human subject, and to follow it through resolution of the disease.

Patients

Single patient, 50 years old male patient, with acute CSCR in one eye and resolved old CSCR in the other eye.

Observations

Observational study in patient with CSCR followed through resolution of the subretinal fluid (52 days). Dark adaptation was assessed using the AdaptDx® (Maculogix Inc.) measured by Rod Intercept time (RIT) in minutes. A normal retinal locus of the same eye on the opposite side of the fovea was used as control. Retinal separation (microns) was measured using Spectralis Optical Coherence Tomography (Spectralis®, HRA + OCT, Heidelberg engineering). Change in time to dark adapt, were correlated with retinal separation measured in microns, during the course of CSCR.

The Rod Intercept time was delayed in the area of detached retina compared to the normal region (control) on presentation with retinal separation (RS) of 104 μm. The Rod Intercept time returned to normal as the retinal separation from retinal pigment epithelium decreased and eventually resolved.

Conclusions

This case shows that delay in dark adaptation is proportional to the amount of separation of neurosensory retina from retinal pigment epithelium in CSCR, this may offer a potential of using DA to characterize visual function in CSCR. The association of dark adaptation response with the state of retinal pigment epithelial function and its ability to predict the recurrence of CSCR needs further evaluation.

Retinal Fundus Multi-Disease Image Dataset (RFMiD): A Dataset for Multi-Disease Detection Research

The world faces difficulties in terms of eye care, including treatment, quality of prevention, vision rehabilitation services, and scarcity of trained eye care experts. Early detection and diagnosis of ocular pathologies would enable forestall of visual impairment. One challenge that limits the adoption of computer-aided diagnosis tool by ophthalmologists is the number of sight-threatening rare pathologies, such as central retinal artery occlusion or anterior ischemic optic neuropathy, and others are usually ignored. In the past two decades, many publicly available datasets of color fundus images have been collected with a primary focus on diabetic retinopathy, glaucoma, age-related macular degeneration and few other frequent pathologies. To enable development of methods for automatic ocular disease classification of frequent diseases along with the rare pathologies, we have created a new Retinal Fundus Multi-disease Image Dataset (RFMiD). It consists of 3200 fundus images captured using three different fundus cameras with 46 conditions annotated through adjudicated consensus of two senior retinal experts. To the best of our knowledge, our dataset, RFMiD, is the only publicly available dataset that constitutes such a wide variety of diseases that appear in routine clinical settings. This dataset will enable the development of generalizable models for retinal screening.

Relationship of Topographic Distribution of Geographic Atrophy to Visual Acuity in Nonexudative Age-Related Macular Degeneration

PURPOSE

To investigate the topographic distribution of geographic atrophy (GA) and to identify an anatomic endpoint that correlates with visual acuity (VA) in eyes with GA.

DESIGN

Retrospective analysis of a multicenter, prospective, randomized controlled trial.

PARTICIPANTS

The Age-Related Eye Disease Study participants with GA secondary to nonexudative age-related macular degeneration.

METHODS

We manually delineated GA on 1654 fundus photographs of 365 eyes. We measured GA areas in 9 subfields on the Early Treatment Diabetic Retinopathy Study (ETDRS) grid and correlated them with VA via a mixed-effects model. We determined the optimal diameter for the central zone by varying the diameter from 0 to 10 mm until the highest r² between GA area in the central zone and VA was achieved. We estimated the VA decline rate over 8 years using a linear mixed model.

MAIN OUTCOME MEASURES

Geographic atrophy area in macular subfields and VA.

RESULTS

The percentage of area affected by GA declined as a function of retinal eccentricity. GA area was higher in the temporal than the nasal region (1.30 ± 1.75 mm² vs. 1.10 ± 1.62 mm²; P = 0.005) and in the superior than the inferior region (1.26 ± 1.73 mm² vs. 1.03 ± 1.53 mm²; P < 0.001). Total GA area correlated poorly with VA (r² = 0.07). Among GA areas in 9 subfields, only GA area in the central zone was associated independently with VA (P < 0.001). We determined 1 mm as the optimal diameter for the central zone in which GA area correlated best with VA (r² = 0.45). On average, full GA coverage of the central 1-mm diameter zone corresponded to 34.8 letters' decline in VA. The VA decline rate was comparable between eyes with initial noncentral and central GA before GA covered the entire central 1-mm diameter zone (2.7 letters/year vs. 2.8 letters/year; P = 0.94).

CONCLUSIONS

The prevalence of GA varies significantly across different macular regions. Although total GA area was associated poorly with VA, GA area in the central 1-mm diameter zone was correlated significantly with VA and may serve as a surrogate endpoint in clinical trials.

Long-Term Effects of Half-Time Photodynamic Therapy on Retinal Sensitivity in Eyes with Chronic Central Serous Chorioretinopathy

The purpose of this study was to evaluate the long-term effects of half-time photodynamic therapy (PDT) on the retinal sensitivity in eyes with chronic central serous chorioretinopathy (CSC). Twenty-two eyes of 22 patients with chronic CSC were studied. PDT was applied with full-dose verteporfin and half-time laser duration. The best-corrected visual acuity (BCVA) and retinal sensitivity in the central 2 and 10 degrees were evaluated at the baseline, and at 12 and 24 months after the half-time PDT. The retinal sensitivity was determined by Macular Integrity Assessment microperimetry (MAIA, Centervue, Padova, Italy). The results showed that the mean retinal sensitivities in the central 2 and 10 degrees were significantly improved at 12 months (25.6 ± 2.79 dB, median; 26.11 dB, 25.6 ± 2.25 dB, median; 25.65 dB, respectively; P < 0.001) and at 24 months (26.3 ± 2.62 dB, median; 27.38 dB, 26.6 ± 2.21 dB, median; 27.45 dB, respectively; P < 0.001) after the treatment compared to that at the baseline (19.2 ± 3.93 dB, median; 19.34 dB, 20.9 ± 2.92 dB, median; 20.9 dB, respectively). The BCVA was also significantly improved from 0.18 ± 0.19 median; 0.15 logarithm of the minimum angle of resolution (logMAR) units at the baseline to 0.07 ± 0.15 median; 0 logMAR units at 12 months (P < 0.001) and to 0.049 ± 0.16 median; -0.039 logMAR units at 24 months (P < 0.001). We conclude that half-time PDT results in a significant improvement of the mean central retinal sensitivity for at least 24 months in eyes with chronic CSC. Thus, half-time PDT is beneficial in resolving chronic CSC for a relatively long period.

Topographic Variation of the Growth Rate of Geographic Atrophy in Nonexudative Age-Related Macular Degeneration: A Systematic Review and Meta-analysis

Purpose

To determine the impact of topographic locations on the progression rate of geographic atrophy (GA).

Methods

We searched in five literature databases up to May 3, 2019, for studies that evaluated the growth rates of GA lesions at different retinal regions. We performed random-effects meta-analyses to determine and compare the GA effective radius growth rates in four location groups defined by two separate classification schemes: (1) macular center point involved (CPI) or spared (CPS) in classification 1, and (2) foveal zone involved (FZI) or spared (FZS) in classification 2. We then estimated the GA growth rate in eight topographic zones and used the data to model the GA expansion.

Results

We included 11 studies with 3254 unique eyes. In studies that used classification 1, the effective radius growth rate was 30.1% higher in the CPS group (0.203 ± 0.013 mm/year) than in the CPI group (0.156 ± 0.011 mm/year) (P < 0.001). This trend became significantly more prominent in classification 2, where the growth rate was 61.7% higher in the FZS group (0.215 ± 0.012 mm/year) than in the FZI group (0.133 ± 0.009 mm/year) (P < 0.001). The estimated GA effective radius growth rates in eight retinal zones fit a Gaussian function, and the modeling of GA expansion gave rise to various GA configurations comparable to clinical observations.

Conclusions

This study indicates that the GA progression rate varies significantly across different retinal locations. Our analysis may shed light on the natural history and underlying mechanism of GA progression.

Macular Integrity Assessment and Fixation Analysis in Chronic Central Serous Chorioretinopathy

Purpose

To investigate retinal sensitivity characteristics associated with morphologic changes in the eyes exhibiting chronic central serous chorioretinopathy (CSC), using macular integrity assessment (MAIA) microperimetry.

Methods

A retrospective, cross-sectional, observational study was constructed. The eyes of patients classified as chronic CSC, according to the onset of subjective symptoms with serous retinal detachment, as confirmed by optical coherence tomography examination, were included in the study. Retinal sensitivity and fixation were analyzed by performing microperimetry examinations using the MAIA instrument.

Results

We reviewed microperimetry examinations of 15 eyes of 15 patients (age: 28-51 years) with chronic CSC and mean best-corrected visual acuity of -0.2 logMAR units. The mean retinal integrity in the chronic CSC group was 49.0 ± 27.6, which was significantly different from the control eyes. The mean average threshold in the eyes with chronic CSC was 24.7 ± 5.8 dB, which also was significantly different from the control eyes. Fixation stability was significantly different between the CSC and control eyes for the P1 parameter (90.1 ± 13.7 versus 99.3 ± 1.5), and for the P2 parameter (97.4 ± 4.0 versus 100.0 ± 0.0).

Conclusion

New microperimetry technology may provide valuable information regarding the visual status of chronic CSC cases. Our findings suggest that retinal sensitivity and fixation stability in chronic CSC eyes may serve as useful indicators for assessing the effectiveness of clinical treatments.

Macular Sensitivity in Eyes with Central Serous Chorioretinopathy

Purpose

To determine macular sensitivity and fixation characteristics in eyes with central serous chorioretinopathy (CSC) using fundus-related microperimetry.

Methods

The authors reviewed 19 eyes with serous elevation within the central 10° due to CSC and 15 normal healthy eyes that had undergone fundus-related microperimetry. The macular sensitivity was measured using the fundus-related microperimeter, MP-1. The best-corrected visual acuity (BCVA), mean retinal sensitivity in the central 10° (central microperimetry, cMP-1) and in the paracentral 10° to 20° (paracentral microperimetry, pMP-1), and fixation stability and location were determined and compared with that of control eyes.

Results

Eyes with CSC showed significantly lower logMAR BCVA (p<0.001), cMP-1, and pMP-1 sensitivity than control eyes (p<0.001, p<0.01, respectively). Eyes with CSC were not significantly different in fixation location (p=1.00) or fixation stability than control eyes (p=0.45). Fixation location was predominantly central in all eyes with CSC; fixation was stable in 17 (89%) and relatively unstable in 2 (11%).

Conclusions

Eyes with CSC showed significantly lower retinal sensitivity not only at the central but also in the paracentral area. Even with decreased BCVA and retinal sensitivity, our patients showed central and stable fixation in their affected eyes.

Idiopathic multifocal choroiditis/punctate inner choroidopathy with acute photoreceptor loss or dysfunction out of proportion to clinically visible lesions

PURPOSE

To report acute/subacute vision loss and paracentral scotomata in patients with idiopathic multifocal choroiditis/punctate inner choroidopathy due to large zones of acute photoreceptor attenuation surrounding the chorioretinal lesions.

METHODS

Multimodal imaging case series.

RESULTS

Six women and 2 men were included (mean age, 31.5 ± 5.8 years). Vision ranged from 20/20-1 to hand motion (mean, 20/364). Spectral domain optical coherence tomography demonstrated extensive attenuation of the external limiting membrane, ellipsoid and interdigitation zones, adjacent to the visible multifocal choroiditis/punctate inner choroidopathy lesions. The corresponding areas were hyperautofluorescent on fundus autofluorescence and were associated with corresponding visual field defects. Full-field electroretinogram (available in three cases) showed markedly decreased cone/rod response, and multifocal electroretinogram revealed reduced amplitudes and increased implicit times in two cases. Three patients received no treatment, the remaining were treated with oral corticosteroids (n = 4), oral acyclovir/valacyclovir (n = 2), intravitreal/posterior subtenon triamcinolone acetate (n = 3), and anti-vascular endothelial growth factor (n = 2). Visual recovery occurred in only three cases of whom two were treated. Varying morphological recovery was found in six cases, associated with decrease in hyperautofluorescence on fundus autofluorescence.

CONCLUSION

Multifocal choroiditis/punctate inner choroidopathy can present with transient or permanent central photoreceptor attenuation/loss. This presentation is likely a variant of multifocal choroiditis/punctate inner choroidopathy with chorioretinal atrophy. Associated changes are best evaluated using multimodal imaging.

Directional Kinetics of Geographic Atrophy Progression in Age-Related Macular Degeneration with Foveal Sparing

PURPOSE

To describe the directional kinetics of the spread of geographic atrophy (GA) spread in eyes with age-related macular degeneration and foveal sparing.

DESIGN

Prospective, noninterventional natural history study: Fundus Autofluorescence Imaging in Age-Related Macular Degeneration (FAM; clinicaltrials.gov identifier, NCT00393692).

SUBJECTS

Participants of the FAM study exhibiting foveal sparing of GA.

METHODS

Eyes were examined longitudinally with fundus autofluorescence (FAF; excitation wavelength, 488 nm; emission wavelength, >500 nm) and near infrared (NIR) reflectance imaging (Spectralis HRA+OCT or HRA2; Heidelberg Engineering, Heidelberg, Germany). Areas of foveal sparing and GA were measured by 2 independent readers using a semiautomated software tool that allows for combined NIR reflectance and FAF image grading (RegionFinder; Heidelberg Engineering). A linear mixed effect model was used to model GA kinetics over time.

MAIN OUTCOME MEASURE

Change of GA lesion size over time (central vs. peripheral progression).

RESULTS

A total of 47 eyes of 36 patients (mean age, 73.8±7.5 years) met the inclusion criteria. Mean follow-up time was 25.2±16.9 months (range, 5.9-74.6 months). Interreader agreement for measurements of GA and foveal-sparing size were 0.995 and 0.946, respectively. Mean area progression of GA toward the periphery was 2.27±0.22 mm(2)/year and 0.25±0.03 mm(2)/year toward the center. Analysis of square root-transformed data revealed a 2.8-fold faster atrophy progression toward the periphery than toward the fovea. Faster atrophy progression toward the fovea correlated with faster progression toward the periphery in presence of marked interindividual differences.

CONCLUSIONS

The results demonstrate a significantly faster centrifugal than centripetal GA spread in eyes with GA and foveal sparing. Although the underlying pathomechanisms for differential GA progression remain unknown, local factors may be operative that protect the foveal retina-retinal pigment epithelial complex. Quantification of directional spread characteristics and modeling may be useful in the design of interventional clinical trials aiming to prolong foveal survival in eyes with GA.

Microperimetric evaluation of chronic central serous chorioretinopathy after half-dose photodynamic therapy

Background

The purpose of this study was to determine baseline clinical factors to correlate the outcome of half-dose verteporfin photodynamic therapy (PDT) in eyes with chronic central serous chorioretinopathy (CSC).

Methods

In this prospective, non-comparative, interventional case series, 14 eyes of 14 patients with chronic CSC who received half-dose verteporfin PDT were examined. The best-corrected visual acuity (BCVA), macular sensitivity in the central 4, 8, and 12 degrees, and fixation stability were evaluated at baseline and at months 1, 3, 6, and 12 after half-dose verteporfin PDT. Macular sensitivity and fixation stability were determined by MP-1 microperimetry.

Results

Mean retinal sensitivity in the central 4 and 8 degrees was significantly better at 1, 3, 6, and 12 months after half-dose verteporfin PDT than at baseline. BCVA was significantly better after half-dose verteporfin PDT but only after 3 months. Fixation was relatively unstable in three eyes at baseline, but became stable at 12 months. BCVA at 12 months was significantly correlated with pre-PDT fixation stability (r = 0.7120, P = 0.0038).

Conclusion

Half-dose verteporfin PDT results in a significant increase in mean central retinal sensitivity for at least 12 months. Our findings indicate that microperimetry is a useful method for evaluating the functional benefits of half-dose verteporfin PDT in eyes with chronic CSC.

Low luminance visual acuity in patients with central serous chorioretinopathy

BACKGROUND

The aim was to determine the low luminance visual acuity in eyes with central serous chorioretinopathy.

METHODS

Seven eyes of seven patients with central serous chorioretinopathy and six eyes of six age-matched normal volunteers were examined. Low luminance visual acuity charts were created by an Apple Power Mac G5 computer and displayed on a cathode ray tube monitor (SONY GDM-F500). The background luminance was set at six different levels from 78.20 cd/m(2) to 0.37 cd/m(2). The visual acuities of the eyes with central serous chorioretinopathy at each of the six luminance levels were compared to those from their fellow eyes and to normal eyes.

RESULTS

The mean visual acuities varied from 0.13, 0.23, 0.29, 0.42, 0.62 to 0.70 logMAR units as luminance varied from high to low. At the lowest luminance (0.37 cd/m(2)), five of the seven eyes could not read any character. The mean visual acuities of the fellow eyes at the same luminance levels were 0.03, 0.06, 0.11, 0.20, 0.27 and 0.45 logMAR units and those of the normal volunteers were 0, 0.03, 0.08, 0.14, 0.23 and 0.38 logMAR units, respectively. The visual acuities of the eyes with central serous chorioretinopathy were significantly poorer than those of the normal eyes at all luminance levels except 0.37 cd/m(2) (p < 0.05 for all).

CONCLUSIONS

Although the eyes from all three groups had 0 logMAR units visual acuity under standard testing condition, the visual acuity of the eyes with central serous chorioretinopathy were significantly worse at low luminance levels. The low luminance visual acuity may provide information on the visual disturbances reported by central serous chorioretinopathy patients with 0 logMAR units visual acuity.

Mutations in the USH1C gene associated with sector retinitis pigmentosa and hearing loss

PURPOSE

To determine the molecular cause of sector retinitis pigmentosa and hearing loss in two affected siblings.

METHODS

Direct DNA sequencing of the USH1C gene was performed in two affected siblings. Putative pathogenic sequence changes were assayed in their parent's chromosomes and in control chromosomes. Clinical examination included visual acuity measurement, visual field measurement, electrophysiologic assessment, and fine matrix mapping. Retinal imaging with fundus photography, scanning laser ophthalmoscope (fundus autofluorescence), and optical coherence tomography was performed. Hearing and vestibular function was also assessed.

RESULTS

The siblings were aged 42 years and 40 years, and both were compound heterozygotes for the p.R103H missense change and the novel splice site change c.2227-1G>A in the USH1C gene. Both alleles were found to be in trans. Neither allele was identified in a panel of 866 control chromosomes, and both were considered pathogenic. Both siblings had sector retinitis pigmentosa restricted to the inferior and nasal retina. Fundus autofluorescence imaging showed a clear demarcation between normal and abnormal areas of retina, which corresponded to areas of reduced sensitivity on fine matrix mapping and loss of visual field. Both siblings had severe hearing loss but were able to develop language.

CONCLUSION

We report a novel molecular cause of sector retinitis pigmentosa associated with hearing loss representing a new phenotype associated with mutations in the USH1C gene.

Visual function following photodynamic therapy for central serous chorioretinopathy: a comparison of automated macular microperimetry versus best-corrected visual acuity

BACKGROUND

The study compares the change in best-corrected visual acuity with the change in central retinal sensitivity before treatment and 6 months after treatment with photodynamic therapy in patients with symptomatic central serous chorio retinopathy.

DESIGN

Prospective, single-centre, interventional case series.

PARTICIPANTS

Eleven consecutive patients with previously untreated central serous chorio retinopathy.

METHODS

Patients had microperimetry and best-corrected visual acuity recorded before and 6 months after treatment with photodynamic therapy. Refracted best-corrected visual acuity was assessed at 2 m and adjusted to give the number of letters read at 1 m. Threshold microperimetry was performed by presenting a Goldman III stimulus to 29 points over the central 12° around fixation. Significant visual improvement at 6 months was defined as a best-corrected visual acuity ≥10 letters or, microperimetry change in mean retinal sensitivity ≥2 decibels (dB).

MAIN OUTCOME MEASURES

Improvement in best-corrected visual acuity compared with microperimetry following photodynamic therapy treatment in patients with central serous chorio retinopathy.

RESULTS

All patients reported a subjective improvement in vision and had complete resolution of subretinal fluid at 6 months. Two patients had a significant improvement in best-corrected visual acuity (mean ± SD +4.2 ± 5.8 letters), compared with all 11 patients who recorded a significant improvement in mean retinal sensitivity (mean ± SD 4.6 ± 1.9 dB) (P < 0.001).

CONCLUSIONS

These data suggest that compared with microperimetry, best-corrected visual acuity is underestimating the effectiveness of photodynamic therapy in the treatment of central serous chorio retinopathy.

Photopigments in central serous chorioretinopathy

PURPOSE

To investigate functional abnormalities in eyes with central serous chorioretinopathy (CSC).

DESIGN

Observational case series.

METHODS

Sixteen eyes with CSC were enrolled. Autofluorescence densitometry was performed to measure the optical density of the photopigments. Serial fundus autofluorescence (FAF) images were obtained by Heidelberg Retina Angiogram 2. We calculated the autofluorescence optical density difference from the FAF images. To compare the distribution pattern of autofluorescence optical density difference to the findings of outer retina, spectral-domain optical coherence tomography (SD-OCT) was performed in the acute phase and after resolution of CSC.

RESULTS

The autofluorescence optical density difference decreased at the serous retinal detachment (SRD) in all 16 eyes. After resolution, the photoreceptor inner and outer segment junction (IS/OS) was irregular in 13 eyes and defective in 3 eyes on SD-OCT. The autofluorescence optical density difference did not improve in any eyes. Five eyes were reexamined 3 month after resolution. In 4 of the 5 eyes, SD-OCT showed that the IS/OS was well delineated and 1 eye defective. The autofluorescence optical density difference improved in 2 of the 4 eyes, but not in the other 2 eyes. In the 1 eye without well-delineated IS/OS, the autofluorescence optical density difference did not improve.

CONCLUSION

In eyes with CSC, the photopigment density decreased at the SRD. The density remained decreased immediately after resolution and showed delayed recovery. The photopigments decreased even in eyes with morphologic recovery of the outer retina.

Central serous chorioretinopathy: an update on pathogenesis and treatment

Central serous chorioretinopathy (CSC) is a chorioretinal disease, incompletely understood with systemic associations, a multifactorial aetiology, and a complex pathogenesis. Increased permeability from the choriocapillaris leads to focal or diffuse dysfunction of the retinal pigment epithelium causing a detachment of the neurosensory retina. CSC has been described in patients with endogenously high levels of corticosteroids as well as in patients with hypercortisolism due to the treatment of ocular or systemic diseases. It is therefore the only 'inflammatory' choroiditis, not proven to be associated with infection that is precipitated or worsened by glucocorticoids. Foveal attenuation, chronic macular oedema, and damage of the foveal photoreceptor layer have been reported as causes of visual loss in CSC. Photoreceptor atrophy in the fovea, despite successful retinal reattachment, typically occurs after a duration of symptoms of approximately 4 months. Treatment should therefore be considered after 3 months if there is angiographic evidence of ongoing foveal leakage in recurrent chronic CSC or in a single CSC episode accompanied by signs of chronic CSC alterations. Based on results of trials conducted so far, it appears that photodynamic therapy with verteporfin is effective and safer than argon laser treatment and should be considered as the treatment of choice, whereas micropulse diode laser photocoagulation seems to be an effective alternative. Glucocorticoid inhibitors are an interesting alternative treatment. Clinical trials are ongoing to test their efficacy. In addition, it is important, where possible, to discontinue any corticosteroid treatment. The possible association of CSC with stress should also be discussed with patients.

Central serous chorioretinopathy

Central serous chorioretinopathy (CSC) is a disease of the retina characterized by serous detachment of the neurosensory retina secondary to one or more focal lesions of the retinal pigment epithelium (RPE). CSC occurs most frequently in mid-life and more often in men than in women. Major symptoms are blurred vision, usually in one eye only and perceived typically by the patient as a dark spot in the centre of the visual field with associated micropsia and metamorphopsia. Normal vision often recurs spontaneously within a few months. The condition can be precipitated by psychosocial stress and hypercortisolism. Ophthalmoscopic signs of CSC range from mono- or paucifocal RPE lesions with prominent elevation of the neurosensory retina by clear fluid - typical of cases of recent onset - to shallow detachments overlying large patches of irregularly depigmented RPE. The spectrum of lesions includes RPE detachments. Granular or fibrinous material may accumulate in the subretinal cavity. Serous detachment often resolves spontaneously. From first contact, counselling about the potential relation to stress and glucocorticoid medication is warranted. After 3 months without resolution of acute CSC or in chronic CSC, treatment should be considered. Resolution of detachment can usually be achieved in acute CSC by focal photocoagulation of leaking RPE lesions or, in chronic CSC, by photodynamic therapy. The effect of therapy on long-term visual outcome is insufficiently documented. Reattachment within 4 months of onset is considered a relevant therapeutic target because prolonged detachment is associated with photoreceptor atrophy. This suggests that the value of treatment depends upon proper selection of cases that will not resolve without therapy. Chronic CSC may be difficult to differentiate from occult choroidal neovascularization secondary to CSC. Patients with chronic CSC who receive glucocorticoid treatment for systemic disease can often be managed without having to discontinue this medication.

Assessment of macular function by microperimetry in unilateral resolved central serous chorioretinopathy

PURPOSE

To determine macular sensitivity and fixation characteristics in patients with unilateral resolved central serous chorioretinopathy (CSC) using fundus-related microperimetry.

METHODS

We reviewed 15 eyes with resolved CSC and 15 normal healthy eyes that had undergone fundus-related microperimetry. The macular sensitivity was measured using the recently introduced fundus-related microperimeter, MP-1. The best-corrected visual acuity (VA) (BCVA), mean retinal sensitivity in the central 10 degrees (central microperimetry, cMP-1) and in the paracentral 10-20 degrees (paracentral microperimetry, pMP-1), and fixation stability and location were determined and compared with measurements in control eyes.

RESULTS

BCVA at the time of this study was 20/20 in all the affected eyes, and fundus examination and optical coherence tomography findings revealed no serous detachment. Eyes with CSC showed statistically significantly lower cMP-1 sensitivity and lower, but not significantly, pMP-1 sensitivity than control eyes (P<0.001, P=0.11, respectively). Eyes with CSC were not significantly different from control eyes in fixation location (P=1.00) or fixation stability (P=0.91). Fixation location was predominantly central in all eyes with CSC; fixation was stable in 12 (80%) and relatively unstable in 3 (20%).

CONCLUSION

Our study shows that eyes with resolved CSC can have lower retinal sensitivity in the central macula than control eyes, even after good VA has been obtained.

Pars plana vitrectomy for diabetic macular oedema: OCT and functional correlations

PURPOSE

A prospective study to evaluate the macular structural and functional effects of pars plana vitrectomy (PPV) for persistent diffuse clinically significant macular oedema (CSMO).

METHOD

A total of 12 patients with persistent diffuse CSMO were recruited and underwent assessment including best-corrected visual acuity, fundus fluorescein angiography, optical coherence tomography (OCT) and fine matrix mapping (FMM) at baseline and over a period of a year poststandard three-port PPV.

RESULTS

The median baseline ETDRS letters score for all 12 patients was 52 (range 41-63) while at 12 months it had increased to 65 (range of 27-68), an improvement of two complete ETDRS lines (P=0.037). Similarly, there was an improvement in the perifoveal cone thresholds (P=0.02). The foveal thickening for all 12 patients ranged from a median of 183 to 751 microm (normal range 126-180 microm) and the macular volume ranged from a median of 2.13 to 6.42 mm(3) (normal <1.66 mm(3)). After surgery, both the median foveal thickness (from 334 to 280 microm) and median macular volume (from 3.24 to 2.61 mm(3)) demonstrated decreases over 12 months (P=0.01). On baseline OCT, the patients fell into two anatomically distinct groups: Group 1 (n=4) had a dome-shaped thickened macula with a partial posterior hyaloid separation and a significantly higher foveal thickness and macular volume than Group 2 (n=8) which had a diffuse low-elevation profile of the thickened macula (P=0.007).

CONCLUSIONS

In this prospective study of PPV for persistent fovea-involving CSMO there was structural and functional improvement.

Five to 15 year follow-up of resolved idiopathic central serous chorioretinopathy

PURPOSE

To recognize the long-term sequelae of resolved idiopathic central serous chorioretinopathy (ICSC) in relation to visual acuity, contrast sensitivity, and lesion size between time elapsed since disease onset.

METHODS

Patients were recruited from fluorescein angiogram records between January 1985 and December 1995 with confirmed ICSC. Visual acuity, contrast sensitivity, and digital fundus photographs were recorded on follow-up. Comparison with the initial red-free photographs were made.

RESULTS

There was no statistically significant deterioration of visual acuity over time compared to eyes with ICSC after initial resolution and the normal eyes. The change of lesion size over time was also statistically insignificant. Contrast sensitivity compared to visual acuity showed positive correlation in both ICSC and normal eyes, but the results were statistically insignificant. Lesion size correlates negatively with visual acuity and contrast sensitivity although this was statistically insignificant.

CONCLUSION

This study shows little, if any, correlation between time and progression of retinal pigment epitheliopathy following resolution of ICSC. Visual acuity did not seem to worsen over time. Our data were not statistically significant, but it does give insight into the natural history of what is still a relatively poorly understood disease.

Use of high spatial resolution perimetry to identify scotomata not apparent with conventional perimetry in the nasal field of glaucomatous subjects

AIM

To examine whether high spatial resolution perimetry (HSRP) could identify fine scale scotomata which may not be apparent with conventional perimetry. The HSRP was performed in the nasal field, as this location is a recognised site for the early occurrence of glaucomatous defects.

METHOD

16 early glaucoma eyes, 17 glaucoma suspect eyes, and 20 age matched healthy control eyes underwent conventional automated perimetry using the 24-2 program of the Humphrey field analyser (HFA) and HSRP. The HSRP was performed in the nasal field by testing 9 x 9 degrees of 100 tested points separated by 1 degree and the results compared with the HFA 24-2 program.

RESULTS

Mean HSRP thresholds were significantly abnormal in the suspect and glaucoma eyes, with elevated levels of asymmetry between the superior and inferior nasal field. Overall, 7/17 (41%) suspect eyes (95% confidence interval 5/17 (29%) to 7/17 (41%)) had nasal scotomata on HSRP, although their HFA 24-2 fields failed to identify any defects. In glaucomatous eyes, 15/16 (94%) eyes had HSRP scotomata (95% CI 14/16 (88%) to 15/16 (94%)). In 12 these coexisted with HFA 24-2 defects at the same location, while in three eyes only HSRP identified scotomata in the nasal field.

CONCLUSION

HSRP can identify scotoma in glaucomatous eyes in the nasal field which may be missed with the lower spatial resolution of conventional perimetry.

Localized retinal dysfunction in central serous chorioretinopathy as measured using the multifocal electroretinogram

PURPOSE

To determine the extent of electrophysiologic dysfunction in patients with central serous chorioretinopathy (CSC).

DESIGN

Prospective observational case series.

PARTICIPANTS

Six patients with unilateral CSC (mean age, 40 years) were recruited into the study.

METHODS

Six patients with CSC underwent multifocal electroretinogram (mfERG) testing on both their clinically affected and opposite uninvolved eyes using the VERIS System, with a stimulus array of 103 scaled hexagons. The first positive peak responses were analyzed within six concentric ring annuli centered on the fovea. Amplitudes and implicit times were compared with those of an age-similar control group.

MAIN OUTCOME MEASURES

Local electroretinographic response amplitudes and implicit times within the central 40 degrees with the mfERG.

RESULTS

All the clinically uninvolved eyes showed mfERG amplitudes and implicit times within the normal range throughout the central 40 degrees of the retina. All six eyes with CSC showed reduced amplitudes and/or delayed implicit times that were limited to the regions of the macula in which clinical changes associated with CSC were apparent.

CONCLUSIONS

We observed electroretinographic changes only in the clinically affected eyes, and these were limited to regions with ophthalmoscopically apparent fundus changes. Our findings do not support the conclusion that functional impairment, as measured by the mfERG, in eyes with CSC extends beyond clinically observed fundus changes. We did not observe abnormal mfERG responses in the clinically normal eyes of such patients.

Abnormalities of fundus autofluorescence in central serous retinopathy

PURPOSE

To report abnormalities of fundus autofluorescence associated with acute and chronic central serous retinopathy (CSR).

DESIGN

A prospective cohort study of patients with CSR was undertaken in which the intensity and spatial distribution of fundus autofluorescence were documented.

METHODS

Fundus autofluorescence was recorded using a confocal laser scanning ophthalmoscope (cLSO) and the images compared with the fundus appearance and fluorescein angiograms in 69 eyes of 63 subjects with either acute or chronic CSR. Areas of increased and decreased autofluorescence were compared with ophthalmoscopic and fluorescein angiography abnormalities. Thirty patients with focal leakage on angiography and serous retinal detachment or pigment epithelial detachment were designated as having acute CSR. Thirty-three patients with diffuse leakage on fluorescein angiography, but without manifest detachment were classified as having chronic CSR.

RESULTS

The mean age was 39 years (range 29-56 years) 14 were female and 49 male. Acute CSR of more than 4 months duration showed a mild diffuse increase in autofluorescence that corresponded with the detached area. The leaking point on the angiogram corresponded to a focal area of intense autofluorescence. In chronic CSR the autofluorescence was very irregular, there being regions with greater and less than the background levels of fluorescence.

CONCLUSION

In acute CSR, increased autofluorescence may occur at the site of leakage and in the area of retinal detachment probably indicating an increased metabolic activity of the retinal pigment epithelium (RPE). Decreased or absent autofluorescence in long-standing lesions may indicate reduced metabolic activity of the RPE due to photoreceptor cell loss. Documenting photoreceptor cell loss with autofluorescence imaging may be useful in identifying patients who would not benefit from laser photocoagulation.

Pattern electroretinography (PERG) and an integrated approach to visual pathway diagnosis

The pattern electroretinogram (PERG) provides an objective measure of central retinal function, and has become an important element of the author's clinical visual electrophysiological practice. The PERG contains two main components, a positivity at approximately 50ms (P50) and a larger negativity at approximately 95ms (N95). The P50 component is affected by macular dysfunction with concomitant reduction in N95. The PERG therefore complements the Ganzfeld ERG in the assessment of patients with retinal disease. In contrast, the ganglion cell origins of the N95 component allow electrophysiological evaluation of ganglion cell function both in primary disease and in dysfunction secondary to optic nerve disease, where selective loss of N95 can be observed. Both macular dysfunction and optic nerve disease can give abnormalities in the visual evoked cortical potential (VEP), and the PERG thus facilitates more meaningful VEP interpretation. This review addresses the origins and recording of the PERG, and then draws on extensive clinical data from patients with genetically determined retinal and macular dystrophies, other retinal diseases and a variety of optic nerve disorders, to present an integrated approach to diagnosis.

Localized scotomata detected with temporal modulation perimetry in central serous chorioretinopathy

AIM

Flicker deficits have been reported in various maculopathies, including age-related macular degeneration. We test whether flicker losses exist in patients with central serous chorioretinopathy (CSC) and whether the size and flicker frequency of the target is important in detecting such losses.

METHODS

We examined four CSC patients with temporal modulation (flicker perception) perimetry using the Medmont auto-flicker module (Medmont Pty Ltd, Melbourne, Vic. Australia), as well as static perimetry and colour vision. One case was examined using sophisticated laboratory equipment to precisely measure their temporal contrast sensitivity function (temporal CSF or de Lange curve) using larger targets to consider the effect of target frequency and size. Two patients were followed longitudinally and tested after resolution of the maculopathy. We compared our patients with an age-matched control group of 11 people.

RESULTS

Temporal modulation perimetry detected larger and more localized defects in all cases of active CSC compared with static perimetry. There appeared to be size and frequency tuning to the deficit, with greatest loss being found at 16 Hz with small (0.5 degree) targets. The losses resolved in one case where the retina recovered in 4 weeks, but remained to a lesser degree in another case who suffered a 2 year long fluctuating course before the CSC subsided.

CONCLUSIONS

Temporal modulation perimetry detects a loss of flicker sensitivity in patients with CSC. Deeper and more clearly defined scotomata are found with a flickering stimulus compared with a steady state one. The greatest losses of flicker sensitivity are found with 16 Hz modulation and with small targets located directly over the lesion. The duration of the disease may be important for recovery of flicker sensitivity. Temporal modulation perimetry appears to be a valuable tool for the confirmation of functional loss due to CSC.

Treatment of pigment epithelial detachments due to age-related macular degeneration with intra-ocular C3F8 injection

PURPOSE

To flatten pigment epithelial detachments (PED) due to age-related macular degeneration in an attempt to visualize the underlying choroidal neovascularization by fluorescein angiography (FA) and reveal a treatment target.

METHODS

Nine patients with PED received intravitreal gas injections via the pars plana and postured face down. Fluorescein angiograms were obtained before and after gas injection. In two patients, retinal scotopic sensitivity was also measured.

RESULTS

Eight patients demonstrated change in the shape and size of the PED following gas injection. Four patients showed a better delineation of underlying structures on FA. Three patients had focal laser treatment to the newly visible choroidal neovascular complex, but this was successful in only one patient with flattening of the PED.

CONCLUSION

Pigment epithelial detachments can be modified by intravitreal gas injection in some patients, but this treatment did not have a major impact on overall outcome or management.

High spatial resolution automated perimetry in glaucoma

BACKGROUND

Automated perimetry is of fundamental importance in assessing visual function in glaucoma. A technique was evaluated to perform high spatial resolution automated perimetry to allow a more detailed assessment of the luminance sensitivity in selected regions of the visual field than is possible with conventional perimetry.

METHOD

High spatial resolution perimetry was performed using a Humphrey automated perimeter by measuring luminance sensitivity across a 9 by 9 degree custom grid of 100 test locations with a separation between adjacent locations of 1 degree. Quantitative analysis of the raw and Gaussian filtered thresholds was performed to assess the repeatability of the technique in normals, glaucoma suspects, and glaucoma patients.

RESULTS

The testing protocol was well tolerated by all subjects. High spatial resolution perimetry in glaucomatous eyes demonstrated fine luminance sensitivity loss not suspected with conventional perimetry. High spatial resolution perimetry also demonstrated reproducible areas of sensitivity loss in some glaucomatous eyes in areas of the visual field which appear normal with conventional programmes. The repeatability of the technique correlated with mean threshold sensitivity and was substantially improved to clinically acceptable levels by Gaussian filtering the thresholds.

CONCLUSION

This technique of high spatial resolution perimetry allows the practical assessment of selected regions of the visual field at higher resolution than conventional perimetry, and may be clinically useful in glaucoma.

Clinical applications of fundus reflection densitometry

Fundus reflection densitometry or retinal densitometry is a non-invasive technique to examine the visual photopigment kinetics in living eyes. The technique is based on the comparison of the reflected light from the fundus in a fully light adapted eye (when all visual photopigment has been bleached) with the reflected light following complete dark adaptation (when the retina contains its maximum amount of visual photopigment). The technique provides a measure of the density of visual photopigment, its time constant of regeneration, its distribution and spectral characteristics if measured at a series of wavelengths. Fundus reflection densitometry in the human eye was introduced 40 years ago. Presently, it is the only available technique from which direct and objective insight can be obtained into visual photopigment. This knowledge is particularly relevant in eyes where abnormalities of photoreceptor function are suspected. This paper summarizes the current knowledge of fundus reflection densitometry in the diseased and in the aging human retina, gathered over the last 30 years. Considerable improvements of the instrument for clinical purposes have been obtained, and are also discussed.

Interphotoreceptor retinoid-binding protein (IRBP). Molecular biology and physiological role in the visual cycle of rhodopsin

The regeneration of visual pigment in rod photoreceptors of the vertebrate retina requires an exchange of retinoids between the neural retina and the retina pigment epithelium (RPE). It has been hypothesized that interphotoreceptor retinoid-binding protein (IRBP) functions as a two-way carrier of retinoid through the aqueous compartment (interphotoreceptor matrix) that separates the RPE and the photoreceptors. The first part of this review summarizes the cellular and molecular biology of IRBP. Work on the IRBP gene indicates that the protein contains a four-fold repeat structure that may be involved in binding multiple retinoid and fatty acid ligands. These repeats and other aspects of the gene structure indicate that the gene has had an active and complex evolutionary history. IRBP mRNA is detected only in retinal photoreceptors and in the pineal gland; expression is thus restricted to the two photosensitive tissues of vertebrate organisms. In the second part of this review, we consider the results obtained in experiments that have examined the activity of IRBP in the process of visual pigment regeneration. We also consider the results obtained on the bleaching and regeneration of rhodopsin in the acutely detached retina, as well as in experiments testing the ability of IRBP to protect its retinoid ligand from isomerization and oxidation. Taken together, the findings provide evidence that, in vivo, IRBP facilitates both the delivery of all-trans retinol to the RPE and the transfer of 11-cis retinal from the RPE to bleached rod photoreceptors, and thereby directly supports the regeneration of rhodopsin in the visual cycle.

Rhodopsin regeneration in the normal and in the detached/replaced retina of the skate

The bleaching and regeneration of rhodopsin in the skate retina was studied by means of fundus reflectometry, both in the normal eyecup preparation and after the retina had been detached and then replaced on the surface of the pigment epithelium (RPE). After bleaching virtually all the rhodopsin in the retinal test area of the normal eyecup, more than 90% of the photopigment was reformed after about 2 hr in darkness; over most of this time course, rhodopsin density rose linearly at a rate of 0.875% min-1 with a half-time of 55 min. Detaching the retina from its pigment epithelium resulted in a number of abnormalities, both structural and functional. Histological examination of the detached/replaced (D/R) retina showed striking alterations in the structural integrity of the RPE cells at their interface with the neural retina. The cells appeared vacuolated and misshapen, and the apical processes of the RPE, which normally ensheath the receptor outer segments, were shredded and free of their association with the visual cells. These morphological changes, as well as dilution of the IRBP content of the subretinal space caused by separation of the tissues, appear to be the main factors contributing to the functional abnormalities in rhodopsin kinetics. But despite these abnormalities and the persistent detachment, the rate of regeneration and the amount of rhodopsin reformed after bleaching were reduced by less than 50% of their normal values. The fact that a significant fraction of the bleached rhodopsin was regenerated under these conditions indicates that 11-cis retinal formed in the RPE was able to traverse a much greater than normal subretinal space to reach the opsin-bearing photoreceptor membranes.

Acute macular neuroretinopathy

Acute macular neuroretinopathy is a rare, unilateral, or bilateral condition of abrupt onset causing parafoveal scotomata and occasionally reduced visual acuity. The features are described in five new cases, and the evolution of the lesions described over a period of 9 months to 9 years. One patient was studied by fine matrix perimetry, which indicated a generalized elevation of thresholds at the macula early in the disorder, together with parafoveal scotomata. The thresholds improved over several months, and the scotomata became less dense. In another case, the scotomata were still present at 9 years, although at this time they were less dense. The condition appears to mainly affect young women, and in this group there is a high incidence of a recent immunologic disturbance suggesting an immune-based etiology.

Probing visual function with psychophysics and photochemistry

New methods using computer based measurements and image analysis techniques can improve and expand our ability to investigate non-invasively the function of the retina in patients. These can provide insight into the underlying mechanism of an abnormality and further our understanding of disease processes.

Long-term follow-up of a prospective trial of argon laser photocoagulation in the treatment of central serous retinopathy

In a prospective randomised trial of argon laser photocoagulation in the management of central serous retinopathy, long-term follow-up (6.4 to 12.1 years) revealed no evidence that treatment significantly influenced the visual outcome as measured by the Snellen chart and by the Farnsworth-Munsell 100-hue test. Treatment did not reduce either the recurrence rate or the prevalence of chronic disease. Complications of treatment were uncommon. The justification for argon laser photocoagulation appears to be limited to the hastening of symptomatic relief by earlier resolution of serous detachment.

Foveal cone photopigment bleaching in central serous retinopathy

Color-matching techniques were used to follow the course of central serous retinopathy in thirteen patients. During periods of neurosensory detachment?, cone optical densities were low. In some patients optical densities remained low following clinical resolution of the disease. In addition, abnormalities of bleaching were observed for one patient in one eye that appeared clinically unaffected during a period of detachment of the fellow eye. Analysis of the data indicates that for longitudinal measurements of optical density, standard Nagel anomaloscope matches can provide an accurate estimate of changes in foveal optical density, although they cannot provide a measure of the absolute optical density.

Clinical psychophysics

New developments in clinical psychophysics allow a non-invasive assessment of visual function which may otherwise not be possible. Measurements of spatial and temporal contrast sensitivity functions, perimetric rod and cone sensitivity, colour vision testing, and newer tests such as hyperacuity thresholds may provide information about the mechanism of an abnormality, allow earlier detection of damage, determination of retinal function in the presence of ocular media disturbances, and allow more sensitive detection of the effects of treatment on visual function. Some methods are more effective in screening or monitoring patients over time while others can be used as research tools to investigate the underlying causes of visual dysfunction. Emerging technologies such as those based on video displays and computer generated graphics and advances in methodology provide potential for new applications. The selection of which aspect of visual function to test depends on the condition (e.g., retinal degeneration or glaucoma), the goals of the investigation, and the facilities available. These non-invasive methods can provide accurate information about retinal function and further improve our ability to quantify and document this most important aspect of the eye--its role in visual function.