Dark-adaptation functions in molecularly confirmed achromatopsia and the implications for assessment in retinal therapy trials.

PURPOSE: To describe the dark-adaptation (DA) functions in subjects with molecularly proven achromatopsia (ACHM) using refined testing conditions with a view to guiding assessment in forthcoming gene therapy trials. METHODS: The DA functions of nine subjects with ACHM were measured and compared with those of normal observers. The size and retinal location of the stimuli used to measure DA sensitivities were varied in four distinct testing condition sets, and the effect of altering these parameters assessed. RESULTS: In three of the four testing condition sets, achromats had significantly higher mean final thresholds than normal observers, whereas in the fourth condition set they did not. A larger, more central stimulus revealed the greatest difference between the final DA thresholds of achromat and normal subjects, and also demonstrated the slowest rate of recovery among the achromat group. CONCLUSIONS: In this, the largest study of DA functions in molecularly proven ACHM to date, we have identified optimal testing conditions that accentuate the relative difference between achromats and normal observers. These findings can help optimize DA testing in future trials, as well as help resolve the dichotomy in the literature regarding the normality or otherwise of DA functions in ACHM. Furthermore, the shorter testing time and less intense adaptation light used in these experiments may prove advantageous for more readily and reliably probing scotopic function in retinal disease, and be particularly valuable in the frequent post therapeutic assessments required in the context of the marked photophobia in ACHM.

Differential modulation of retinal degeneration by Ccl2 and Cx3cr1 chemokine signalling.

Microglia and macrophages are recruited to sites of retinal degeneration where local cytokines and chemokines determine protective or neurotoxic microglia responses. Defining the role of Ccl2-Ccr2 and Cx3cl1-Cx3cr1 signalling for retinal pathology is of particular interest because of its potential role in age-related macular degeneration (AMD). Ccl2, Ccr2, and Cx3cr1 signalling defects impair macrophage trafficking, but have, in several conflicting studies, been reported to show different degrees of age-related retinal degeneration. Ccl2/Cx3cr1 double knockout (CCDKO) mice show an early onset retinal degeneration and have been suggested as a model for AMD. In order to understand phenotypic discrepancies in different chemokine knockout lines and to study how defects in Ccl2 and/or Cx3cr1 signalling contribute to the described early onset retinal degeneration, we defined primary and secondary pathological events in CCDKO mice. To control for genetic background variability, we compared the original phenotype with that of single Ccl2, Cx3cr1 and Ccl2/Cx3cr1 double knockout mice obtained from backcrosses of CCDKO with C57Bl/6 mice. We found that the primary pathological event in CCDKO mice develops in the inferior outer nuclear layer independently of light around postnatal day P14. RPE and vascular lesions develop secondarily with increasing penetrance with age and are clinically similar to retinal telangiectasia not to choroidal neovascularisation. Furthermore, we provide evidence that a third autosomal recessive gene causes the degeneration in CCDKO mice and in all affected re-derived lines and subsequently demonstrated co-segregation of the naturally occurring RD8 mutation in the Crb1 gene. By comparing CCDKO mice with re-derived CCl2(-/-)/Crb1(Rd8/RD8), Cx3cr1(-/-)/Crb1(Rd8/RD8) and CCl2(-/-)/Cx3cr1(-/-)/Crb1(Rd8/RD8) mice, we observed a differential modulation of the retinal phenotype by genetic background and both chemokine signalling pathways. These findings indicate that CCDKO mice are not a model of AMD, but a model for an inherited retinal degeneration that is differentially modulated by Ccl2-Ccr2 and Cx3cl1-Cx3cr1 chemokine signalling.

The drusenlike phenotype in aging Ccl2-knockout mice is caused by an accelerated accumulation of swollen autofluorescent subretinal macrophages.

PURPOSE: Drusen, which are defined clinically as yellowish white spots in the outer retina, are cardinal features of age-related macular degeneration (AMD). Ccl2-knockout (Ccl2(-/-)) mice have been reported to develop drusen and phenotypic features similar to AMD, including an increased susceptibility to choroidal neovascularization (CNV). This study was conducted to investigate the nature of the drusenlike lesions in vivo and further evaluate the Ccl2(-/-) mouse as a model of AMD. METHODS: The eyes of 2- to 25-month-old Ccl2(-/-) and C57Bl/6 mice were examined in vivo by autofluorescence scanning laser ophthalmoscopy (AF-SLO) and electroretinography, and the extent of laser-induced CNV was measured by fluorescein fundus angiography. The retinal morphology was also assessed by immunohistochemistry and quantitative histologic and ultrastructural morphometry. RESULTS: The drusenlike lesions of Ccl2(-/-) mice comprised accelerated accumulation of swollen CD68(+), F4/80(+) macrophages in the subretinal space that were apparent as autofluorescent foci on AF-SLO. These macrophages contained pigment granules and phagosomes with outer segment and lipofuscin inclusions that may account for their autofluorescence. Only age-related retinal pigment epithelium (RPE) damage, photoreceptor loss, and sub-RPE deposits were observed but, despite the accelerated accumulation of macrophages, we identified no spontaneous development of CNV in the senescent mice and found a reduced susceptibility to laser-induced CNV in the Ccl2(-/-) mice. CONCLUSIONS: These findings suggest that the lack of Ccl2 leads to a monocyte/macrophage-trafficking defect during aging and to an impaired recruitment of these cells to sites of laser injury. Other, previously described features of Ccl2(-/-) mice that are similar to AMD may be the result of aging alone.

Evaluation of autofluorescence imaging with the scanning laser ophthalmoscope and the fundus camera in age-related geographic atrophy.

PURPOSE: To compare fundus autofluorescence images (FAF) between a modified fundus camera (mFC) and a confocal scanning laser ophthalmoscope (cSLO). DESIGN: Evaluation of diagnostic technology. METHODS: Thirty-two eyes of 16 patients with age-related geographic atrophy (GA) treated in an institutional setting were included. FAF images were obtained with both the cSLO (excitation, 488 nm; emission, > 500 nm) and the mFC (excitation, approximately 500 to 610 nm; emission, approximately 675 to 715 nm). Using established algorithms, images were graded by two independent observers and agreements were evaluated. The main outcome measures were image quality, quantification of total atrophy, and classification of FAF patterns. RESULTS: In two eyes with advanced cataract (lens grade 7 according to the Age-Related Eye Disease Study classification), FAF image quality with both systems was not sufficient for any meaningful analysis. In the remaining 30 eyes, the mean differences of the interobserver agreements for atrophy quantification were 0.16 mm2 (95% confidence interval [CI], 0.07 to 0.38) for mFC and 0.15 mm2 (95% CI, -0.04 to 0.33) for cSLO images. Because of inferior signal-to-noise ratios, FAF pattern classification was possible in a lower number of mFC images (69%) compared with cSLO images (88%). CONCLUSIONS: This study suggests that the agreements for atrophy quantification are similar with both devices. The lesser visualization of FAF patterns with the mFC and thus inferior determination of disease markers may be the result of the nonconfocality and the use of single instead of mean images compared with the cSLO. These findings may be important for the design of interventional trials as well as the routine use of FAF imaging in age-related geographic atrophy.

Glare and halo with refractive correction.

BACKGROUND: The aim of this investigation was to compare glare and halo with various methods of refractive correction. METHODS: Ninety-eight eyes of healthy pre-presbyopes were analysed for the presence of glare and halo using computer-generated stimuli. Subjects were divided into three groups: emmetropes without correction, single vision plastic lens spectacle wearers (with clean and dirty lenses) or single-vision soft contact lens wearers. RESULTS: No significant difference in glare was found among groups. Significant differences were noted in halos between emmetropes and both contact lens (p<0.001) and uncleaned spectacle groups (p<0.05) but not with cleaned spectacles. The reduction in halo size after cleaning the lenses was significant (p<0.0187). CONCLUSIONS: Contact lens and unclean spectacle wearers both have significantly larger halos than emmetropes and those wearing cleaned spectacle lenses. Unclean spectacles may affect the accuracy of results in psychophysical and clinical testing.

Real-time in vivo imaging of retinal cell apoptosis after laser exposure.

PURPOSE: To investigate whether the detection of apoptosing retinal cells (DARC) could detect cells undergoing apoptosis in a laser model of retinal damage. METHODS: Laser lesions were placed, with the use of a frequency-doubled Nd:YAG laser, on the retina in 34 eyes of anesthetized Dark Agouti rats. Lesion size and laser-induced retinal elevation were analyzed using in vivo reflectance imaging. Development of retinal cell apoptosis was assessed using intravitreal fluorescence-labeled annexin 5 in vivo with DARC technology from baseline until 90 minutes after laser application. Histologic analysis of retinal flat mounts and cross-sections was performed. RESULTS: The lateral and anteroposterior depth extension of the zone of laser damage was significantly larger for higher exposure settings. A strong diffuse signal, concentrated at the outer retina, was seen with DARC for low exposures (<300 ms and <300 mW). In comparison, higher exposures (>300 ms and >300 mW) resulted in detectable hyperfluorescent spots, mainly at the level of the inner retinal layers. Dose-dependent effects on spot density and positive correlation of spot density between lesion size (P < 0.0001) and retinal elevation (P < 0.0001) were demonstrated. Histology confirmed the presence of apoptosing retinal cells in the inner nuclear and the ganglion cell layers. CONCLUSIONS: This is the first time that DARC has been used to determine apoptotic effects in the inner nuclear layer. The ability to monitor changes spatially and temporally in vivo promises to be a major advance in the real-time assessment of retinal diseases and treatment effects.

Assessment of rat and mouse RGC apoptosis imaging in vivo with different scanning laser ophthalmoscopes.

PURPOSE: We have recently described a novel way of imaging apoptosing retinal ganglion cells in vivo in the rat. This study investigated if this technique could be used in the mouse, and whether the Heidelberg Retina Angiograph II (HRAII) was appropriate. METHODS: Retinal ganglion cell (RGC) death was induced by intravitreal injections in rat and mouse eyes using staurosporine. Fluorescent-labeled apoptosing cells were detected by imaging with both the HRAII and a prototype Zeiss confocal scanning laser ophthalmoscope (cSLO). Averaged in vivo images were analyzed and results compared with histologic analysis. RESULTS: Fluorescent points (FPs) used as a measure of RGC apoptosis in vivo were detected in the mouse eye but only with the HRAII and not the Zeiss cSLO. The HRAII was able to detect 62% more FPs in rat than the Zeiss cSLO. Both cSLOs showed peak FP counts at the 5- to 10-microm range in rat and mouse. Maximal FP counts were detected in the superior and superior temporal regions in the rat, with no obvious pattern of distribution in the mouse. The HRAII was found to have more FP correspondence with histologically identified apoptosing RGCs. CONCLUSIONS: To our knowledge, this is the first demonstration of visualized apoptosing RGC in vivo in a mouse. The improved image quality achieved with the HRAII compared with the Zeiss cSLO was validated by histology. This together with its enhanced maneuverability and the fact that it is already commercially available make the HRAII a potential tool for the early detection and diagnosis of glaucomatous disease in patients.

Targeting amyloid-beta in glaucoma treatment.

The development of the devastating neurodegenerative condition, Alzheimer's disease, is strongly associated with amyloid-beta (Abeta) deposition, neuronal apoptosis, and cell loss. Here, we provide evidence that implicates these same mechanisms in the retinal disease glaucoma, a major cause of irreversible blindness worldwide, previously associated simply with the effects of intraocular pressure. We show that Abeta colocalizes with apoptotic retinal ganglion cells (RGC) in experimental glaucoma and induces significant RGC apoptosis in vivo in a dose- and time-dependent manner. We demonstrate that targeting different components of the Abeta formation and aggregation pathway can effectively reduce glaucomatous RGC apoptosis in vivo, and finally, that combining treatments (triple therapy) is more effective than monotherapy. Our work suggests that targeting the Abeta pathway provides a therapeutic avenue in glaucoma management. Furthermore, our work demonstrates that the combination of agents affecting multiple stages in the Abeta pathway may be the most effective strategy in Abeta-related diseases.

Exploration of the psychophysics of a motion displacement hyperacuity stimulus.

PURPOSE: To explore the summation properties of a motion-displacement hyperacuity stimulus with respect to stimulus area and luminance, with the goal of applying the results to the development of a motion-displacement test (MDT) for the detection of early glaucoma. METHODS: A computer-generated line stimulus was presented with displacements randomized between 0 and 40 minutes of arc (min arc). Displacement thresholds (50% seen) were compared for stimuli of equal area but different edge length (orthogonal to the direction of motion) at four retinal locations. Also, MDT thresholds were recorded at five values of Michelson contrast (25%-84%) for each of five line lengths (11-128 min arc) at a single nasal location (-27,3). Frequency-of-seeing (FOS) curves were generated and displacement thresholds and interquartile ranges (IQR, 25%-75% seen) determined by probit analysis. RESULTS: Equivalent displacement thresholds were found for stimuli of equal area but half the edge length. Elevations of thresholds and IQR were demonstrated as line length and contrast were reduced. Equivalent displacement thresholds were also found for stimuli of equivalent energy (stimulus area x [stimulus luminance - background luminance]), in accordance with Ricco's law. There was a linear relationship (slope -0.5) between log MDT threshold and log stimulus energy. CONCLUSIONS: Stimulus area, rather than edge length, determined displacement thresholds within the experimental conditions tested. MDT thresholds are linearly related to the square root of the total energy of the stimulus. A new law, the threshold energy-displacement (TED) law, is proposed to apply to MDT summation properties, giving the relationship T = K logE where, T is the MDT threshold, Kis the constant, and E is the stimulus energy.

Comparison of fundus autofluorescence and minimum-motion measurements of macular pigment distribution profiles derived from identical retinal areas.

The optical density of macular pigment was measured at twelve retinal locations in ten subjects by minimum motion photometry, comparing 460 nm with 580 nm or 550 nm. Fundus autofluorescence images were obtained for the same subjects with a scanning laser ophthalmoscope. Optical density was computed from mean calibrated grey-scale values for a central circular field and for annular segments, identical to areas tested psychophysically, and for complete annuli. Psychophysical assessments of optical density were similar irrespective of whether 550 nm or 580 nm was used. Optical density values derived psychophysically showed a linear correlation with assessments based on identical sampled areas of annular segments (slope = 0.98, r2 = 0.97) or complete annuli (slope = 0.89, r2 = 0.96) in autofluorescence images.

Classification of fundus autofluorescence patterns in early age-related macular disease.

PURPOSE: To describe and classify patterns of abnormal fundus autofluorescence (FAF) in eyes with early nonexudative age-related macular disease (AMD). METHODS: FAF images were recorded in eyes with early AMD by confocal scanning laser ophthalmoscopy (cSLO) with excitation at 488 nm (argon or OPSL laser) and emission above 500 or 521 nm (barrier filter). A standardized protocol for image acquisition and generation of mean images after automated alignment was applied, and routine fundus photographs were obtained. FAF images were classified by two independent observers. The kappa statistic was applied to assess intra- and interobserver variability. RESULTS: Alterations in FAF were classified into eight phenotypic patterns including normal, minimal change, focal increased, patchy, linear, lacelike, reticular, and speckled. Areas with abnormal increased or decreased FAF signals may or may not have corresponded to funduscopically visible alterations. For intraobserver variability, kappa of observer I was 0.80 (95% confidence interval [CI]0.71-0.89) and of observer II, 0.74. (95% CI, 0.64-0.84). For interobserver variability, kappa was 0.77 (95% CI, 0.67-0.87). CONCLUSIONS: Various phenotypic patterns of abnormal FAF can be identified with cSLO imaging. Distinct patterns may reflect heterogeneity at a cellular and molecular level in contrast to a nonspecific aging process. The results indicate that the classification system yields a relatively high degree of intra- and interobserver agreement. It may be applicable for determination of novel prognostic determinants in longitudinal natural history studies, for identification of genetic risk factors, and for monitoring of future therapeutic interventions to slow the progression of early AMD.

Age-related macular disease: how to assess the retina using scanning laser techniques?

Age-related macular disease (AMD) is the leading cause of legal blindness among the elderly in Western nations. The magnitude of the problem will undoubtedly grow, as age is a significant risk factor and the number of people aged 65 and over is projected to increase. The most frequent cause of severe visual loss associated with AMD is irreversible degeneration of the overlying neurosensory retina, caused by the growth of choroidal neovascularization or, alternatively, the development of geographic atrophy of the retinal pigment epithelium. Today, we are able to image the human retina in vivo. Recently developed imaging techniques provide better assessment of retinal pathology than conventional ophthalmoscopy alone. This overview presents the most recent devices available for retinal imaging, which mainly exploit laser technology such as scanning laser ophthalmoscopy. Its basic principles, as well as its characteristics for imaging and functional assessment of the retina, are described. Lastly, potential benefits for clinical routine, rehabilitation strategies in AMD, and future research aspects are discussed.

Retinal ganglion cell apoptosis in glaucoma is related to intraocular pressure and IOP-induced effects on extracellular matrix.

PURPOSE: To investigate the effect of IOP on retinal ganglion cell (RGC) apoptosis and correlate the effects with IOP-induced changes in extracellular matrix (ECM) in the retina and optic nerve head (ONH) in glaucomatous rat eyes. METHODS: Thirty-seven Dark Agouti rats had elevated IOP induced in the left eye by hypertonic saline episcleral vein injections. Eyes were examined at 3 months histologically for RGC apoptosis and expression of specific ECM components. RESULTS: RGC apoptosis was significantly related to IOP exposure (integral DeltaIOP P <0.001; peak IOP P <0.01). In the RGC layer, elevated IOP correlated positively to a significant increase in MMP-9 activity (P <0.001), tissue inhibitor of matrix metalloproteinase (TIMP-1) (P <0.05), and collagen I (P <0.01), and negatively correlated to deposition of laminin (P <0.05) and TGF-beta2 (P <0.05). There was a significant correlation between MMP-9 activity and both RGC apoptosis (P <0.001) and loss of laminin (P <0.01). IOP exposure was also associated with increased deposition of TGF-beta2 and collagen I at the ONH (P <0.01). CONCLUSIONS: The results demonstrated that RGC apoptosis in glaucoma correlates strongly with elevated IOP and is significantly associated with IOP-induced changes in specific ECM components in the RGC layer. The study shows for the first time a link between MMP-9, laminin degradation, RGC apoptosis, and IOP exposure in glaucoma. The findings suggest that abnormal ECM remodeling in the glaucomatous retina may relate to RGC death and support the notion that the retina is a primary site of injury in glaucoma.

Comparison of fundus autofluorescence with photopic and scotopic fine-matrix mapping in patients with retinitis pigmentosa and normal visual acuity.

PURPOSE: To compare psychophysically determined spatial variations in photopic and scotopic sensitivity across the macula in patients with retinitis pigmentosa (RP) and normal visual acuity who manifest an abnormal high-density ring of fundus autofluorescence (AF). METHODS: Eleven patients with a clinical diagnosis of RP were examined. All had rod-cone dystrophy (International Society for Clinical Electrophysiology of Vision [ISCEV]-standard ERGs), visual acuity of 6/9 or better, and an abnormal parafoveal annulus of high density AF. Fine-matrix mapping (FMM) was performed over macular areas of abnormal high-density AF under photopic and dark-adapted conditions. Pattern ERGs (PERGs) were performed in 9 of 11 patients, by using different sizes of circular checkerboards. RESULTS: Rings of high-density AF varied between patients (approximately 3 degrees -18 degrees in diameter). Photopic sensitivity was preserved over central macular areas, but there was a gradient of sensitivity loss over high-density segments of the ring and severe threshold elevation outside the arc of the ring. Scotopic sensitivity losses were more severe, and they encroached on areas within the ring. The radius of the high-density ring correlated with the lateral extent of preserved photopic sensitivity (r=0.86) and PERG data. CONCLUSIONS: High-density rings of AF, which are present in some patients with RP with normal visual acuity, demarcate areas of preserved central photopic sensitivity. Scotopic sensitivity losses encroach on areas within the ring of high density and may reflect dysfunction before accumulation of lipofuscin.

Real-time imaging of single nerve cell apoptosis in retinal neurodegeneration.

Apoptotic nerve cell death is implicated in the pathogenesis of several devastating neurodegenerative conditions, including glaucoma and Alzheimer's and Parkinson's diseases. We have devised a noninvasive real-time imaging technique using confocal laser-scanning ophthalmoscopy to visualize single nerve cell apoptosis in vivo, which allows longitudinal study of disease processes that has not previously been possible. Our method utilizes the unique optical properties of the eye, which allow direct microscopic observation of nerve cells in the retina. We have been able to image changes occurring in nerve cell apoptosis over hours, days, and months and show that effects depend on the magnitude of the initial apoptotic inducer in several models of neurodegenerative disease in rat and primate. This technology enables the direct observation of single nerve cell apoptosis in experimental neurodegeneration, providing the opportunity for detailed investigation of fundamental disease mechanisms and the evaluation of interventions with potential clinical applications, together with the possibility of taking this method through to patients.

Fundus autofluorescence in Stargardt macular dystrophy-fundus flavimaculatus.

PURPOSE: To quantify autofluorescence (AF) levels in patients with Stargardt macular dystrophy-fundus flavimaculatus (STGD-FFM), and to identify patterns of AF. DESIGN: Observational, comparative study. METHODS: Prospective study. SETTINGS: Patients were recruited at Moorfields Eye Hospital. STUDY POPULATION: Forty-three STGD-FFM patients aged 20 to 40 years and 35 age-matched normal volunteers. The right eye was chosen arbitrarily for measures of AF. INTERVENTION: The AF images were obtained using a confocal scanning laser ophthalmoscope. Levels of AF across the macula were measured. The distribution of AF was also evaluated. In 36 patients (84%) pattern electroretinogram (PERG) and full-field ERG were obtained and results were evaluated with respect to levels of AF. MAIN OUTCOME MEASURES: Values of AF, AF distribution, PERG, and ERG. RESULTS: Normal or high AF at the center of the macula with high AF temporally or nasally or both was detected in 17 patients (39%). In nine (21%), low AF at the center of the macula with normal or low AF temporally or nasally or both was found. Levels of AF were normal throughout the macula in six patients (14%). In 11 (26%), high, normal, and low levels of AF were found. All patients tested with low AF at the center of the macula and normal or low AF temporally or nasally or both had peripheral cone/rod dysfunction. None of the patients tested that had normal or high AF at the fovea and high AF temporally or nasally, or normal AF throughout the macula, had peripheral cone/rod dysfunction. CONCLUSION: AF is not universally high in STGD-FFM. Some patients have normal or low AF. Autofluorescence patterns appear to relate to functional abnormalities.

Photopic and scotopic fine matrix mapping of retinal areas of increased fundus autofluorescence in patients with age-related maculopathy.

PURPOSE: To investigate photopic and scotopic sensitivity of retinal areas that show increased fundus autofluorescence (FAF) in patients with age-related maculopathy (ARM). METHODS: FAF was imaged with a modified confocal scanning laser ophthalmoscope (cSLO). Fine matrix mapping (FMM) was performed with a modified field analyzer. Photopic and scotopic thresholds were obtained at 100 locations on a 9 degrees x 9 degrees matrix with 1 degrees spacing, centered on a macular area of increased FAF. Inclusion criteria included ARM fundus changes, areas of increased FAF, central and stable fixation, and visual acuity of 20/40 or better. RESULTS: FAF images were reviewed in 436 patients with age-related maculopathy (ARM), of whom 38 met the inclusion criteria. FMM was performed in seven eyes of seven patients. Areas of increased FAF in patients with late ARM (choroidal neovascularization or geographic atrophy) showed normal or only mildly abnormal photopic, but severely reduced scotopic, sensitivity. The central area of increased FAF corresponding to a large foveal druse in a patient with ARM showed moderately reduced photopic and severely reduced scotopic sensitivity. In the other patients with ARM with drusen, areas of increased FAF showed normal or near-normal photopic sensitivity, but moderately reduced scotopic sensitivity. CONCLUSIONS: In retinal areas of increased FAF in patients with ARM, scotopic sensitivity loss considerably exceeded photopic sensitivity loss. This finding is in line with histologic data that have demonstrated a preferential loss of rods in ARM, but does not explain the magnitude of sensitivity loss. The study shows that increased FAF in ARM has a functional correlate.

Pattern ERG correlates of abnormal fundus autofluorescence in patients with retinitis pigmentosa and normal visual acuity.

PURPOSE: To examine the functional significance of central abnormalities present in fundus autofluorescence (AF) images in patients with rod-cone dystrophy and good visual acuity. METHODS: Thirty patients were selected according to three criteria: a clinical diagnosis of retinitis pigmentosa (RP) confirmed with International Society for Clinical Electrophysiology of Vision (ISCEV) standard ERGs, a parafoveal ring of increased high density on fundus AF imaging, and a visual acuity of 20/30 or better. Macular function was assessed with pattern electroretinography (PERG) to checkerboard stimuli of different field sizes. Fundus AF imaging was performed with a confocal scanning laser ophthalmoscope. RESULTS: The radius of the parafoveal ring of high density varied between 1.5 degrees and 9 degrees. The PERG P50 amplitude correlated highly with the radius of the ring of increased autofluorescence (r = 0.80, P < 0.0005, n = 30). PERGs to smaller circular field sizes were present, but increasing field size to beyond that of the high-density autofluorescence ring did not produce further increases in P50 amplitude. There was a high correlation between the minimum stimulus size required to elicit a maximum-amplitude PERG and the radius of the ring (r = 0.87). CONCLUSIONS: The high correlation between AF imaging and PERG, an established technique in the assessment of central retinal function, demonstrates the likelihood that autofluorescence abnormalities have functional significance and may therefore be a valuable additional parameter in the monitoring of these patients.

Phenotype of retinitis pigmentosa associated with the Ser50Thr mutation in the NRL gene.

BACKGROUND: We previously reported an Ser50Thr mutation in the NRL gene as a cause of autosomal dominant retinitis pigmentosa. OBJECTIVE: To determine the characteristic features of the autosomal dominant retinitis pigmentosa phenotype associated with the NRL Ser50Thr mutation in affected individuals from 4 related families. METHODS: Clinical records were available for 21 affected individuals; 7 underwent more extensive electrophysiologic and psychophysical testing. RESULTS: Night blindness was the first symptom to manifest, with onset between birth and age 16 years. Difficulty with peripheral vision was experienced between 20 and 37 years of age. Visual acuity was well preserved in younger individuals, but those older than 30 years frequently had substantial visual loss (6/36 or worse) associated with macular atrophy. Electrophysiologic testing revealed a nondetectable scotopic electroretinogram with relative preservation of the photopic electroretinogram and pattern electroretinography in the 3 youngest patients tested (aged 15-18 years). In older individuals, all components of the electroretinogram were nondetectable. Dark-adapted visual fields in younger individuals were greatly impaired, but their photopic fields remained relatively well preserved. Older patients had photopic fields limited to just a few degrees. Distinctive peripapillary chorioretinal atrophy seems to develop as the disorder progresses. CONCLUSIONS: The NRL Ser50Thr mutation is associated with selective loss of scotopic function before age 20 years. With time, however, the photopic system becomes affected, leading to loss of the photopic visual field and of visual acuity.

Retinal pigment epithelium translocation after choroidal neovascular membrane removal in age-related macular degeneration.

PURPOSE: To test the feasibility of a new surgical technique and to assess visual function over the translocated retinal pigment epithelium (RPE) cells in patients operated on for subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration (ARMD). DESIGN: Retrospective, noncomparative, interventional case series. PARTICIPANTS: Nine patients with previously untreated exudative ARMD underwent surgical excision of the subfoveal CNV with RPE translocation and were observed for 12 to 32 months. METHODS: The surgery consisted of a standard three-port pars plana vitrectomy, excision of the CNV, and RPE translocation. Pre- and postoperative ocular examination included best-corrected visual acuity measurement, fundus color stereo photography, and fundus fluorescein angiography. Optical coherence tomography and confocal laser scanning ophthalmoscopy (cLSO) were performed after surgery. A crossfixation target and a single-point flashing light were projected on different areas of the posterior pole using a cLSO. Photopic 10 to 2 perimetry, photopic fine matrix mapping, and cLSO microperimetry were also performed after surgery in six patients. MAIN OUTCOME MEASURES: Optical coherence tomography cross-sectional scans and cLSO RPE autofluorescence were recorded to detect the presence of viable translocated RPE. Visual acuity, fixation, photopic 10 to 2 perimetry, photopic fine matrix mapping, and cLSO microperimetry were used to test central visual function. RESULTS: Retinal pigment epithelium was translocated successfully at the time of CNV removal from the edge of the RPE defect to a subfoveal location in seven of nine patients. One patient experienced proliferative vitreoretinopathy, but significant hemorrhage was not a feature. Optical coherence tomography showed the translocated RPE as an area of increased optical reflectivity with optical shadowing external to it. Confocal laser scanning ophthalmoscopy showed autofluorescence of the translocated RPE. The crossfixation target was seen when projected on the translocated RPE. During eccentric fixation, the patients could see a flashing point-target projected on the translocated RPE. Photopic 10 to 2 perimetry, photopic fine-matrix mapping, and cLSO microperimetry showed the presence of central visual function. CONCLUSIONS: The authors propose that translocation of RPE at the time of CNV removal, from the edge of the RPE defect to a subfoveal location, may have a role in the surgical management of ARMD.