The Frequency-Response Electroretinogram Distinguishes Cone and Abnormal Rod Function in rd12 Mice

Early studies on Rpe65 knockout mice reported that remaining visual function was attributable to cone function. However, this finding has been challenged more and more as time has passed. Electroretinograms (ERGs) showed that rd12 mice, a spontaneous animal model of RPE65 Leber’s congenital amaurosis, had sizeable photopic responses. Unfortunately, the recorded ERG waveform was difficult to interpret because of a remarkably delayed peak-time, which resembles a rod response more than a cone response. Here, we compare flicker ERGs in animals with normal rod and cone function (C57BL/6J mice), pure rod function (cpfl5 mice), and pure cone function (Rho^-/- mice) under different adaptation levels and stimulus intensities. These responses were then compared with those obtained from rd12 mice. Our results showed that normal rods respond to low frequency flicker (5 and 15 Hz) and that normal cones respond to both low and high frequency flicker (5–35 Hz). As was seen in cpfl5 mice, rd12 mice had recordable responses to low frequency flicker (5 and 15Hz), but not to high frequency flicker (25 and 35 Hz). We hypothesize that abnormal rods may be the source of residual vision in rd12 mice, which is proved correct here with double mutant rd12mice. In this study, we show, for the first time, that frequency-response ERGs can effectively distinguish cone- and rod-driven responses in the rd12 mouse. It is another simple and valid method for evaluating the respective contributions of retinal rods and cones.     

Chronic Kidney Disease and Diabetic Retinopathy in Patients with Type 2 Diabetes

Purpose

To explore the relationship between chronic kidney disease (CKD) and diabetic retinopathy (DR) in a representative population of type 2 diabetes mellitus (DM2) patients in Catalonia (Spain).

Methods

This was a population-based, cross-sectional study. A total of 28,344 patients diagnosed with DM2 who had recorded ophthalmologic and renal functional examinations were evaluated. Data were obtained from a primary healthcare electronic database of medical records. CKD was defined as an estimated glomerular filtration ratio (eGFR) of <60 ml/min/1.73m² and/or urine albumin to creatinine ratio (UACR) ≥30 mg/g. DR was categorized as non-vision threatening diabetic retinopathy and vision threatening diabetic retinopathy.

Results

CKD was associated with a higher rate of DR [OR], 95% confidence interval [CI], 1.5 (1.4–1.7). When we analyzed the association between different levels of UACR and DR prevalence observed that DR prevalence rose with the increase of UACR levels, and this association was significant from UACR values ≥10 mg/g, and increased considerably with UACR values ≥300mg/g (Odds ratio [OR], 95% confidence interval [CI], 2.0 (1.6–2.5). This association was lower in patients with eGFR levels 44 to 30 mL/min/1.73m² [OR], 95% confidence interval [CI], 1.3 (1.1–1.6).

Conclusions

These results show that CKD, high UACR and/or low eGFR, appear to be associated with DR in this DM2 population.     

2型糖尿病患者尿视黄醇结合蛋白与视网膜病变的相关性

目的 探讨2型糖尿病患者尿视黄醇结合（RBP）与视网膜病变相关性。方法 采用酶联免疫法检测158例2型糖尿病患者24h尿视黄醇结合蛋白排泄（24hURBP）及24h尿白蛋白排泄（24hUAE）,并同时用眼底镜仔细检查其眼氏。结果 糖尿病视网膜病变（DR）发生率随着24hURBP、24hUAE增加而显著增高,24hURBP、24hUAE也随DR的程度加重而显著增加。结论 2型糖尿病患者DR与尿RBP、尿白蛋白呈正相关。     

2型糖尿病患者血糖波动与糖尿病视网膜病变的相关性分析

目的:探讨2型糖尿病(T2DM)患者血糖波动与糖尿病视网膜病变(DR)的关系.方法:T2DM患者进行眼底照相或眼底荧光造影,根据DR程度分为糖尿病背景期视网膜病变(BDR)组、糖尿病增殖期视网膜病变(PDR)组、无视网膜病变(NDR)组,记录年龄、性别、体重指数、病程、测量血压、糖化血红蛋白、空腹胰岛素、餐后2h胰岛素、空腹C-肽、餐后2hC-肽、血脂指标.选取三组中上述基线指标具有可比性的病例共106例(BDR组38例,PDR组35例,NDR组33例)纳入观察.采用动态血糖监测系统(CGMS)连续监测患者血糖72 h.结果:各组间平均血糖水平(MBG)、血糖标准差(SDBG)、平均血糖波动幅度(MAGE)及血糖波动最大幅度(LAGE)相比较有统计学差异(P＜0.05).Spearman相关分析显示,糖尿病视网膜病变(DR)与MBG、SDBG、MAGE及LAGE呈正相关(P＜0.05).校正MBG后,糖尿病视网膜病变(DR)与SDBG、MAGE及LAGE的相关系数分别为0.297、0.396、0.284(P＜0.01).结论:血糖波动与糖尿病视网膜病变(DR)的发生发展有关,应尽早干预.     

Acute Zonal Occult Outer Retinopathy in Japanese Patients: Clinical Features,Visual Function,and Factors Affecting Visual Function

Purpose

To evaluate the clinical features and investigate their relationship with visual function in Japanese patients with acute zonal occult outer retinopathy (AZOOR).

Methods

Fifty-two eyes of 38 Japanese AZOOR patients (31 female and 7 male patients; mean age at first visit, 35.0 years; median follow-up duration, 31 months) were retrospectively collected: 31 untreated eyes with good visual acuity and 21 systemic corticosteroid-treated eyes with progressive visual acuity loss. Variables affecting the logMAR values of best-corrected visual acuity (BCVA) and the mean deviation (MD) on Humphrey perimetry at initial and final visits were examined using multiple stepwise linear regression analysis.

Results

In untreated eyes, the mean MD at the final visit was significantly higher than that at the initial visit (P = 0.00002). In corticosteroid-treated eyes, the logMAR BCVA and MD at the final visit were significantly better than the initial values (P = 0.007 and P = 0.02, respectively). The final logMAR BCVA was 0.0 or less in 85% of patients. Variables affecting initial visual function were moderate anterior vitreous cells, myopia severity, and a-wave amplitudes on electroretinography; factors affecting final visual function were the initial MD values, female sex, moderate anterior vitreous cells, and retinal atrophy.

Conclusions

Our data indicated that visual functions in enrolled patients significantly improved spontaneously or after systemic corticosteroids therapy, suggesting that Japanese patients with AZOOR have good visual outcomes during the follow-up period of this study. Furthermore, initial visual field defects, gender, anterior vitreous cells, and retinal atrophy affected final visual functions in these patients.     

2型糖尿病眼底增殖改变与冠状动脉病变关系的研究

目的:探讨2型糖尿病眼底增殖改变与冠状动脉病变的关系.方法:对330例2型糖尿病合并冠心痛患者进行眼底检测及冠状动脉造影,根据眼底是否具有增殖性改变进行对比分析,并应用多因素分析方法探讨与眼底增殖改变相关的危险因素.结果:2型糖尿病伴眼底增殖改变者,年龄较大,病程较长,尿微量白蛋白阳性检出率增加,TG、TC及HbA1c显著性升高;多支血管病变及钙化病变受累比例增高;Logistic回归分析显示,经调整糖尿病病程、HbA1c、微量白蛋白尿后,2型糖尿病眼底增殖改变仍与冠状动脉钙化相关.结论:2型糖尿病眼底增殖改变与冠状动脉钙化相关.     

Transretinal ERG Recordings from Mouse Retina: Rod and Cone Photoresponses

There are two distinct classes of image-forming photoreceptors in the vertebrate retina: rods and cones. Rods are able to detect single photons of light whereas cones operate continuously under rapidly changing bright light conditions. Absorption of light by rod- and cone-specific visual pigments in the outer segments of photoreceptors triggers a phototransduction cascade that eventually leads to closure of cyclic nucleotide-gated channels on the plasma membrane and cell hyperpolarization. This light-induced change in membrane current and potential can be registered as a photoresponse, by either classical suction electrode recording technique^1,2 or by transretinal electroretinogram recordings (ERG) from isolated retinas with pharmacologically blocked postsynaptic response components^3-5. The latter method allows drug-accessible long-lasting recordings from mouse photoreceptors and is particularly useful for obtaining stable photoresponses from the scarce and fragile mouse cones. In the case of cones, such experiments can be performed both in dark-adapted conditions and following intense illumination that bleaches essentially all visual pigment, to monitor the process of cone photosensitivity recovery during dark adaptation^6,7. In this video, we will show how to perform rod- and M/L-cone-driven transretinal recordings from dark-adapted mouse retina. Rod recordings will be carried out using retina of wild type (C57Bl/6) mice. For simplicity, cone recordings will be obtained from genetically modified rod transducin α-subunit knockout (Tα^-/-) mice which lack rod signaling⁸.     

Functional Analysis of Missense Mutations in Kv8.2 Causing Cone Dystrophy with Supernormal Rod Electroretinogram

Mutations in KCNV2 have been proposed as the molecular basis for cone dystrophy with supernormal rod electroretinogram. KCNV2 codes for the modulatory voltage-gated potassium channel α-subunit, Kv8.2, which is incapable of forming functional channels on its own. Functional heteromeric channels are however formed with Kv2.1 in heterologous expression systems, with both α-subunit genes expressed in rod and cone photoreceptors. Of the 30 mutations identified in the KCNV2 gene, we have selected three missense mutations localized in the potassium channel pore and two missense mutations localized in the tetramerization domain for analysis. We characterized the differences between homomeric Kv2.1 and heteromeric Kv2.1/Kv8.2 channels and investigated the influence of the selected mutations on the function of heteromeric channels. We found that two pore mutations (W467G and G478R) led to the formation of nonconducting heteromeric Kv2.1/Kv8.2 channels, whereas the mutations localized in the tetramerization domain prevented heteromer generation and resulted in the formation of homomeric Kv2.1 channels only. Consequently, our study suggests the existence of two distinct molecular mechanisms involved in the disease pathology.     

Brain Function Alterations in Patients with Diabetic Nephropathy Complicated by Retinopathy Under Resting State Conditions Assessed by Voxel-Mirrored Homotopic Connectivity

Objective: The voxel-mirrored homologous connection (VHMC) technique was applied to detect resting brain function alterations in patients with diabetic nephropathy and retinopathy (DNR), and their relationships with clinical manifestations in the kidneys and eyes are discussed.Methods: Twenty-two patients with DNR and 22 healthy controls (HCs) similarly matched in age, sex, and educational background were recruited. Resting-state functional magnetic resonance imaging scans were performed for all subjects. Retinal fundus photography and renal biopsy were employed to observe the clinical features of the kidney and retina. Pearson correlation analysis was used to analyze the relationship between clinical manifestations and experimental results.Results: Compared with the HCs, patients with DNR showed decreased mean VMHC values in the bilateral middle temporal gyrus, bilateral middle occipital gyrus (BMOG), and bilateral medial frontal gyrus. The receiver operating characteristic curve analysis of each brain region confirmed that the accuracy of the area under the curve was excellent. The results showed that the average VHMC value of BMOG signals was positively correlated with the urinary protein to creatinine ratio in female subjects (r = 0.626; P<.05). Nonetheless, no such correlation was noted among the male subjects.Conclusion: There were significant changes in brain function in DNR patients compared to the control group. Changes in the central nervous system in patients with DNR were mainly due to the dual negative effects of kidney function and diabetes mellitus.Abbreviations: ACR = albumin/creatinine ratio; BMFG = bilateral medial frontal gyrus; BMOG = bilateral middle occipital gyrus; BMTG = bilateral middle temporal gyrus; DN = diabetic nephropathy; DNR = diabetic nephropathy complicated by retinopathy; DR = diabetic retinopathy; fMRI = functional magnetic resonance imaging; HC = healthy control; MRI = magnetic resonance imaging; PCR = protein to creatinine ratio; ROC = receiver operating characteristic; VHMC = voxel-mirrored homologous connection     

High Prevalence of Lower Extremity Peripheral Artery Disease in Type 2 Diabetes Patients with Proliferative Diabetic Retinopathy

Little is known about the relationship between lower extremity peripheral arterial disease (PAD) and proliferative diabetic retinopathy (PDR) in type 2 diabetes (T2D). Here, we explored the relationship between sight-threatening PDR and PAD. We screened for diabetic retinopathy (DR) and PAD in hospitalized patients with T2D. Patients with a diabetic duration of more than 10 years, HbA1c ≥7.5%, eGFR ≥60mL/min/1.73m2 and with PDR or with no diabetic retinopathy (NDR) were eligible for this cross-sectional study. Severities of DR were graded by digital retinal photographs according to the Early Treatment Diabetic Retinopathy Study (ETDRS) scale. We assessed PAD by measuring Ankle Brachial Index (ABI), Toe Brachial Index (TBI) and Doppler ultrasound. Statistical analyses were performed using SPSS 17.0 software. Of the 1544 patients, 169 patients with extreme eye (57 PDR and 112 NDR) phenotypes met the inclusion criteria. Patients with PDR had a significantly higher proportion of low ABI (≤0.99) and high ABI (≥1.3) than patients with NDR (28.1% and 15.8% vs. 14.3% and 6.2% respectively, P<0.05). PDR patients also had lower TBI than NDR patients (0.56±0.09 vs. 0.61±0.08, P<0.01). The proportion of patients with abnormal duplex ultrasound was higher in PDR than in NDR (21.1% vs. 9.8%, P<0.001). This showed that PDR associated with PAD could be defined in multiple ways: abnormal ABI (≤0.9) (OR = 3.61, 95% CI: 1.15–11.26), abnormal TBI (OR = 2.84, 95% CI: 1.19–6.64), abnormal duplex (OR = 3.28, 95% CI: 1.00–10.71), and critical limb ischemia (OR = 5.52, 95% CI: 2.14–14.26). Moreover, PDR was a stronger independent correlation factor for PAD than a diabetic duration of 10 years. In conclusion, PAD is more common in PDR than in NDR. It implies that PDR and PAD are mostly concomitant in T2D. We should focus on screening PAD in patients with PDR in clinical practice.     

The 5-Year Onset and Regression of Diabetic Retinopathy in Chinese Type 2 Diabetes Patients

Purpose

To determine the rate and risk factors of diabetic retinopathy (DR) onset and regression in Chinese type 2 diabetes mellitus patients.

Methods

This is a 5-year community-based prospective study. The demographic information, systemic examination results and ophthalmological test results of each participant were collected. The study outcomes were DR incidence, defined as the onset of DR in at least one eye, and DR regression, defined as full regression from existing DR to no retinopathy without invasive treatments. The associations between each potential risk factor and the outcomes were studied.

Results

In total, 778 participants were enrolled. There were 322 patients without DR at baseline, of which 151 participants developed DR during follow-up (DR incidence rate = 46.89%). Baseline hyperglycemia and high blood pressure were two independent risk factors associated with DR incidence. Among the 456 participants with existing DR at entry, 110 fully recovered after 5 years (DR regression rate = 24.12%). Low baseline glucose and low serum triglyceride were two independent factors associated with DR regression.

Conclusions

DR incidence occurred more frequently in patients with hyperglycemia and high blood pressure. DR regression occurred mostly in patients with lower glucose and lower serum triglyceride levels among Chinese type 2 diabetes patients.     

Bax-Induced Apoptosis in Leber's Congenital Amaurosis: A Dual Role in Rod and Cone Degeneration

Pathogenesis in the Rpe65^−/− mouse model of Leber''s congenital amaurosis (LCA) is characterized by a slow and progressive degeneration of the rod photoreceptors. On the opposite, cones degenerate rapidly at early ages. Retinal degeneration in Rpe65 ^−/− mice, showing a null mutation in the gene encoding the retinal pigment epithelium 65-kDa protein (Rpe65), was previously reported to depend on continuous activation of a residual transduction cascade by unliganded opsin. However, the mechanisms of apoptotic signals triggered by abnormal phototransduction remain elusive. We previously reported that activation of a Bcl-2-dependent pathway was associated with apoptosis of rod photoreceptors in Rpe65^−/− mice during the course of the disease. In this study we first assessed whether activation of Bcl-2-mediated apoptotic pathway was dependent on constitutive activation of the visual cascade through opsin apoprotein. We then challenged the direct role of pro-apoptotic Bax protein in triggering apoptosis of rod and cone photoreceptors.Quantitative PCR analysis showed that increased expression of pro-apoptotic Bax and decreased level of anti-apoptotic Bcl-2 were restored in Rpe65^−/−/Gnat1^−/− mice lacking the Gnat1 gene encoding rod transducin. Moreover, photoreceptor apoptosis was prevented as assessed by TUNEL assay. These data indicate that abnormal activity of opsin apoprotein induces retinal cell apoptosis through the Bcl-2-mediated pathway. Following immunohistological and real-time PCR analyses, we further observed that decreased expression of rod genes in Rpe65-deficient mice was rescued in Rpe65^−/−/Bax^−/− mice. Histological and TUNEL studies confirmed that rod cell demise and apoptosis in diseased Rpe65^−/− mice were dependent on Bax-induced pathway. Surprisingly, early loss of cones was not prevented in Rpe65^−/−/Bax^−/− mice, indicating that pro-apoptotic Bax was not involved in the pathogenesis of cone cell death in Rpe65-deficient mice.This is the first report, to our knowledge, that a single genetic mutation can trigger two independent apoptotic pathways in rod and cone photoreceptors in Rpe65-dependent LCA disease. These results highlight the necessity to investigate and understand the specific death signaling pathways committed in rods and cones to develop effective therapeutic approaches to treat RP diseases.     

High Prevalence of Diabetic Retinopathy in Diabetic Patients Concomitant with Metabolic Syndrome

Objective

To evaluate the relationship between metabolic syndrome (MetS) and the prevalence of diabetic retinopathy (DR).

Research Design and Methods

We conducted a case-controlled study, with data obtained from 2,551 Chinese participants between 18–79 years of age (representing a population of 1,660,500 in a district of Beijing). 74 cases of DR were found following data assessment by two 45° digital retinal images. Subjects without DR (NDR group) selected from the remaining 2,477 subjects were matched 1:1 to the DR group by HbA1c. MetS was defined by incorporating diagnostic criteria of the American Heart Association/National Heart, Lung, and Blood Institute (AHA/NHLBI) and the International Diabetes Federation (IDF).

Results

There were no statistical differences between the DR group and NDR group in a number of biological or laboratory tests. However, the percentage of patients with DR increased vs. patients without DR with the number of MetS components from 1 to 5 (14.3% vs. 85.7%, 38.9% vs. 61.1%, 49.1% vs. 50.9%, 61.4% vs. 38.6% and 83.3% vs. 16.7%, respectively) (Pearson χ² = 9.938, P = 0.037). The trend to develop DR with MetS was significantly higher than that without MetS (NMetS) (χ² = 5.540, P = 0.019). MetS was an independent statistical indicator of the presence of DR after adjusting for age and sex [odds ratio (95% CI): 2.701(1.248–5.849), P = 0.012], which is still the case with an additional adjustment for WC, SBP, TC, HbA1c and duration of diabetes [odds ratio (95% CI): 2.948(1.134–7.664), P = 0.027].

Conclusion

DR is one of the diabetic microvascular complications. Apart from poor glycemic control, the concomitance of other metabolic factors can also influence DR. MetS, defined as a cluster of metabolic risk factors, is a strong and independent indicator of DR, even to the same extent as glycemic control.     

Disparities between Ophthalmologists and Patients in Estimating Quality of Life Associated with Diabetic Retinopathy

Background

This study aimed to evaluate and compare the utility values associated with diabetic retinopathy (DR) in a sample of Chinese patients and ophthalmologists.

Methods

Utility values were evaluated by both the time trade-off (TTO) and rating scale (RS) methods for 109 eligible patients with DR and 2 experienced ophthalmologists. Patients were stratified by Snellen best-corrected visual acuity (BCVA) in the better-seeing eye. The correlations between the utility values and general vision-related health status measures were analyzed. These utility values were compared with data from two other studies.

Results

The mean utility values elicited from the patients themselves with the TTO (0.81; SD 0.10) and RS (0.81; SD 0.11) methods were both statistically lower than the mean utility values assessed by ophthalmologists. Significant predictors of patients’ TTO and RS utility values were both LogMAR BCVA in the affected eye and average weighted LogMAR BCVA. DR grade and duration of visual dysfunction were also variables that significantly predicted patients’ TTO utility values. For ophthalmologists, patients’ LogMAR BCVA in the affected eye and in the better eye were the variables that significantly predicted both the TTO and RS utility values. Patients’ education level was also a variable that significantly predicted RS utility values. Moreover, both diabetic macular edema and employment status were significant predictors of TTO and RS utility values, whether from patients or ophthalmologists. There was no difference in mean TTO utility values compared to our American and Canadian patients.

Conclusions

DR caused a substantial decrease in Chinese patients’ utility values, and ophthalmologists substantially underestimated its effect on patient quality of life.     

重症肺炎患者血清IL-2水平及与呼吸功能的相关性分析

目的:研究重症肺炎患者血清白细胞介素-2(IL-2)水平及与呼吸功能的相关性。方法:选择2013年5月~2016年5月在我院进行诊治的重症肺炎患者80例为观察组,同期在我院呼吸科入住的一般呼吸道感染患者80例为对照组,分别检测两组的血清IL-2水平,记录呼吸频率,取动脉血检测氧分压和氧合指数,采用单因素回归分析血清IL-2与呼吸功能的相关性。结果:观察组的血清IL-2水平明显高于对照组(P0.05);观察组的呼吸频率明显高于对照组(P0.05),氧分压和氧和指数均明显低于对照组(P0.05);血清IL-2水平与呼吸频率呈明显正相关(P0.05),与氧分压和氧和指数呈明显负相关(P0.05)。结论:重症肺炎患者血清IL-2水平明显升高,且与呼吸功能密切相关,能作为判断重症肺炎患者呼吸功能的客观检查指标。     

Synaptic Transfer between Rod and Cone Pathways Mediated by AII Amacrine Cells in the Mouse Retina

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Human Rod Monochromacy: Linkage Analysis and Mapping of a Cone Photoreceptor Expressed Candidate Gene on Chromosome 2q11

We have performed linkage analysis in eight families with rod monochromacy, an autosomal recessively inherited condition with complete color blindness. Significant linkage was found with markers located at the pericentromeric region of chromosome 2. A maximum lod score of 5.36 was obtained for marker D2S2333 at θ = 0.00. Mapping of meiotic breakpoints localized the disease gene between markers D2S2187 and D2S2229. Homozygosity for a number of subsequent markers indicating identity by descent was found in two families and provides evidence for a further refinement of the locus proximal to D2S373. This defines an interval of ≈3 cM covering theACHM2locus for rod monochromacy. Radiation hybrid mapping of theCNGA3gene encoding the α-subunit of the cGMP gated cation channel in human cone photoreceptors resulted in a maximum lod score of 16.1 with marker D2S2311 combined with a calculated physical distance of 6.19cR_10,000. Screening of the CEPH YAC library and subsequent STS mapping indicated the physical order cen–D2S2222–D2S2175–(D2S2187/D2S2311)–qtel ofmarkers on 2q11 and showed that theCNGA3gene maps most closely to D2S2187 and D2S2311. These data indicate that theCNGA3gene maps within the critical interval of theACHM2locus for rod monochromacy and thus is a candidate gene for this disease.     

2 型糖尿病患者凝血功能水平与血管病变发生的相关性

目的:探讨2型糖尿病患者凝血功能及血清肿瘤坏死因子α(TNF-α)及白细胞介素18(IL-18)水平与糖尿病血管病变的关系。方法:选择2014年6月-2015年10月在我院接受治疗的2型糖尿病患者83例作为研究对象,根据患者疾病进展情况将其分为血管病变组(45例)和无血管病变组(38例)。测定两组患者凝血酶时间(TT)、活化部分凝血酶原时间(APTT)、凝血酶原时间(PT)、纤维蛋白原(Fg)、血糖(Glu)、糖化血红蛋白(Hb A1c)、肿瘤坏死因子α(TNF-α)及白细胞介素18(IL-18)水平;采用logistics回归分析2型糖尿病患者发生血管病变的危险因素。结果:血管病变组患者Glu,Hb A1c及Fg水平均显著高于无血管病变组,而APTT及PT水平均显著低于无血管病变组,差异均具有统计学意义(P0.05);两组间TT水平比较,差异无统计学意义(P0.05)。血管病变组患者血清中TNF-α及IL-18水平均高于无血管病变组患者,差异具有统计学意义(P0.05)。Hb A1c,Fg,TNF-α以及IL-18水平异常是2型糖尿病患者发生血管病变的独立危险因素(OR=1.23,1.45,2.632,3.884,P0.05)。结论:凝血功能紊乱及炎症反应是2型糖尿病患者发生血管病变的重要因素,临床应给予重视。     

Visual Function and Cortical Organization in Carriers of Blue Cone Monochromacy

Carriers of blue cone monochromacy have fewer cone photoreceptors than normal. Here we examine how this disruption at the level of the retina affects visual function and cortical organization in these individuals. Visual resolution and contrast sensitivity was measured at the preferred retinal locus of fixation and visual resolution was tested at two eccentric locations (2.5° and 8°) with spectacle correction only. Adaptive optics corrected resolution acuity and cone spacing were simultaneously measured at several locations within the central fovea with adaptive optics scanning laser ophthalmoscopy (AOSLO). Fixation stability was assessed by extracting eye motion data from AOSLO videos. Retinotopic mapping using fMRI was carried out to estimate the area of early cortical regions, including that of the foveal confluence. Without adaptive optics correction, BCM carriers appeared to have normal visual function, with normal contrast sensitivity and visual resolution, but with AO-correction, visual resolution was significantly worse than normal. This resolution deficit is not explained by cone loss alone and is suggestive of an associated loss of retinal ganglion cells. However, despite evidence suggesting a reduction in the number of retinal ganglion cells, retinotopic mapping showed no reduction in the cortical area of the foveal confluence. These results suggest that ganglion cell density may not govern the foveal overrepresentation in the cortex. We propose that it is not the number of afferents, but rather the content of the information relayed to the cortex from the retina across the visual field that governs cortical magnification, as under normal viewing conditions this information is similar in both BCM carriers and normal controls.