張麗珠 黎鏵 馬銀燕 李娟娟
作者單位:云南大學(xué)附屬醫(yī)院 云南省第二人民醫(yī)院眼科 云南省眼科醫(yī)院,昆明 650021
Stargardt病是一類臨床上相對常見的青少年黃斑營養(yǎng)不良,以黃斑中心區(qū)視網(wǎng)膜色素上皮細(xì)胞(Retinal pigment epithelium,RPE)中脂褐質(zhì)堆積,光感受器細(xì)胞損傷為典型臨床特征,其眼底病變呈進(jìn)行性發(fā)展。既往對不同病變階段的臨床特征有過較多的文獻(xiàn)報道,但都側(cè)重于某一種或某幾種影像手段的觀察分析。近年來眼底多模式影像技術(shù)廣泛運(yùn)用,從不同原理、不同角度反映病情的特征和發(fā)展,我們收集了不同病變階段的Stargardt病患者,對其進(jìn)行多模式眼底影像檢查,對比不同病變階段同一種檢查手段下的病變特征,也對比同一病變階段下不同影像檢查的優(yōu)劣。以期全面分析多模式影像技術(shù)在Stargardt病自然病程中不同的運(yùn)用價值,現(xiàn)總結(jié)如下。
納入標(biāo)準(zhǔn):所有患者符合Gass對Stargardt病的臨床描述:雙眼眼底可見黃斑區(qū)色素紊亂,中心凹反光消失,黃斑區(qū)對稱性斑點(diǎn)狀脫色素或“橢圓形”萎縮灶,呈金箔樣反光,可伴或不伴后極部或周邊黃色斑點(diǎn)。伴有不同程度的光感受器及RPE細(xì)胞萎縮。
排除標(biāo)準(zhǔn):排除其他可能混淆的遺傳性黃斑營養(yǎng)不良疾病、視網(wǎng)膜相關(guān)遺傳性疾病及其他相關(guān)視網(wǎng)膜脈絡(luò)膜疾病。
回顧性系列病例研究。選擇2016年5月至2019年8 月在云南大學(xué)附屬醫(yī)院眼科門診經(jīng)過多種影像檢查及基因測序而確診的Stargardt病患者28 例(56眼),其中男18例,女10例,首診年齡6~32(12.5±6.3)歲。5例因雙眼自幼視力不佳就診,21例因兒童眼科矯正視力不提高而轉(zhuǎn)診。所有患者視力范圍為:指數(shù)~0.6。28 例患者中15 例均基因檢測證實ABCA4
基因位點(diǎn)突變。所有患者根據(jù)眼底病變特征分為以下三期:初期:中心視力下降,眼底表現(xiàn)為對稱性黃斑區(qū)色素紊亂,中心凹反光消失,少量脫色素,黃斑區(qū)萎縮范圍較??;進(jìn)行期:眼底中心凹反光消失,黃斑深層見到灰黃色小斑點(diǎn),或形成一個橫橢圓形境界清楚的萎縮區(qū),面積大于1個視盤直徑,金箔樣反光。晚期:黃斑萎縮進(jìn)行性加重,呈青灰色或金箔樣反光,可見萎縮的脈絡(luò)膜血管,并有形態(tài)不規(guī)則的色素斑沉著。28 例患者中,初期患者5 例,進(jìn)行期患者15 例,晚期患者8例。5例初期病變的患者最佳矯正視力(BCVA)為0.05~0.6,15例進(jìn)行期患者BCVA為指數(shù)~0.2,8例病變晚期患者視力為指數(shù)~0.08,矯正均無提高。所有患者均行BCVA、裂隙燈顯微鏡、散瞳后行以下檢查:眼底彩色照像、眼底自發(fā)熒光(Autofluorescence,AF)、眼底熒光素血管造影(FFA)、光學(xué)相干斷層掃描(OCT)、炫彩眼底照相(Multicolor,MC)、血流成像OCT(OCT angiography,OCTA)。眼底彩色照相采用Nidek眼底照相機(jī)進(jìn)行。眼底自發(fā)熒光及眼底熒光血管造影檢查采用德國海德堡HRA眼底血管造影儀進(jìn)行,患者散瞳后首先拍攝后極部眼底像,隨后行488 nm激光波長進(jìn)行眼底自發(fā)熒光掃描,調(diào)節(jié)敏感度旋鈕,連續(xù)采集3~5張圖像,使用Herdelberg Eye Explore 軟件處理,得到AF像。隨后給予患者10%熒光素鈉2.5 ml快速推注入肘靜脈內(nèi),8~10 s后加濾光片進(jìn)行各個象限拍攝,起初為連續(xù)拍攝,后改為間歇拍攝,獲取FFA圖像。OCT檢查采用海德堡Spectralis HRA OCT進(jìn)行,掃描參數(shù)為:掃描深度5~8 mm,掃描部位為以病變部位為中心進(jìn)行水平掃描。眼底炫彩成像采用海德堡炫彩成像OCT進(jìn)行,在炫彩成像模式下,采用紅外激光(波長532 nm)、綠色激光(波長518 nm)和藍(lán)色激光(波長486 nm)同時掃描并疊加至100幀獲得清晰的炫彩圖像。OCTA采用海德堡OCTA進(jìn)行,該裝置的中心波長為840 nm,采集速度為85 000次A-Scan/s,獲得3 mm×3 mm的掃描,在掃描過程中采用Eye-Tracking動眼追蹤技術(shù)。最后選擇病變部位顯示清晰,層次清楚,OCTA中無分層錯誤等圖像質(zhì)量與位置較佳的影像進(jìn)行標(biāo)記保存。
5例(10眼)初期病變的患者中,3例眼底彩色照片暫未見雙眼對稱性橢圓形萎縮病灶,僅見黃斑區(qū)中心凹反光消失,色素紊亂,2 例(4 眼)患者可見黃斑區(qū)較?。ㄐ∮? PD)的雙眼對稱性橢圓形萎縮病灶,黃斑區(qū)青灰色金箔樣反光(見圖1A),均合并有后極部散在黃色斑點(diǎn)。15例(30眼)病變進(jìn)行期患者,眼底彩色照相示黃斑區(qū)可見較大(大于1 PD)的對稱性橢圓形“牛眼狀”萎縮灶,金箔樣反光(見圖1B)。8例(16眼)病變晚期患者黃斑區(qū)萎縮灶面積擴(kuò)大,呈大片青灰色橢圓形萎縮灶,占據(jù)后極部大部分視網(wǎng)膜區(qū)域,萎縮區(qū)域內(nèi)可見脈絡(luò)膜血管(見圖1C)。
圖1.不同病變階段Stargardt病眼底彩色照相A:病變初期患者眼底照相,可見黃斑中心凹光反射消失,中心凹附近較小區(qū)域萎縮,周邊合并黃色斑點(diǎn)。B:病變進(jìn)行期患者眼底照相,可見黃斑區(qū)大于1 PD的橢圓形“牛眼狀”萎縮灶,呈金箔樣反光。C:病變晚期患者眼底照相,可見后極部呈大片青灰色橢圓形萎縮灶Figure 1.Color fundus photography of Stargardt's disease at different stages.A:Fundus photography of a patient in the early stage,shows that the light reflection of the fovea macula has disappeared,a small area near the fovea has atrophied,and yellow spots are observed around it.B:Fundus photography of a patient in the progressive stage,shows an oval "bull's-eye" atrophic lesion larger than 1 PD in the macular area,reflecting like gold foil.C:Fundus photograph of a patient in the advanced stage shows a large bluish-gray oval atrophic lesion at the posterior pole.
5例(10眼)初期病變的患者眼底自發(fā)熒光可見黃斑區(qū)一面積較小的低自發(fā)熒光區(qū)域,低自發(fā)熒光外圍可見一圈相對高的自發(fā)熒光,周圍黃色斑點(diǎn)處呈點(diǎn)狀高自發(fā)熒光(見圖2A)。15例(30眼)病變進(jìn)行期患者,可見黃斑區(qū)對稱的橢圓形低自發(fā)熒光區(qū),低自發(fā)熒光的面積較初期病變擴(kuò)大(大于1 PD),血管弓附近及外圍黃色斑點(diǎn)處呈點(diǎn)狀高自發(fā)熒光(見圖2B)。8例(16眼)病變晚期患者自發(fā)熒光中,低自發(fā)熒光區(qū)域面積顯著擴(kuò)大,黃斑區(qū)可見邊界清楚的極低自發(fā)熒光,周圍大片斑駁狀低自發(fā)熒光,較前兩期患者不同,晚期病變中黃色斑點(diǎn)處部分呈點(diǎn)狀低熒光(見圖2C)。
圖2.不同病變階段Stargardt病眼底自發(fā)熒光A:初期患者眼底自發(fā)熒光,黃斑區(qū)面積較小的低自發(fā)熒光區(qū)域,外圍可見一圈相對高的自發(fā)熒光,周圍黃色斑點(diǎn)處呈點(diǎn)狀高自發(fā)熒光。B:進(jìn)行期患者眼底自發(fā)熒光,黃斑區(qū)對稱的橢圓形低自發(fā)熒光區(qū),面積較初期病變擴(kuò)大(大于1 PD),外圍黃色斑點(diǎn)處呈點(diǎn)狀高自發(fā)熒光。C:晚期患者眼底自發(fā)熒光,黃斑區(qū)可見邊界清楚的極低自發(fā)熒光,周圍大片斑駁狀低自發(fā)熒光,黃色斑點(diǎn)處部分呈點(diǎn)狀低熒光Figure 2.Fundus autofluorescence of Stargardt's disease at different stages.A:Autofluorescence of a patient in the early stage.A small area of low autofluorescence is observed in the macular area,with a circle of relatively high autofluorescence in the periphery.The surrounding yellow spots are dotted with high autofluorescence.B:Autofluorescence of a patient in the progressive stage.The symmetrical oval area of low autofluorescence in the macular area is larger than that of the initial lesion (greater than 1 PD),and the yellow spots around the periphery are dotted with high autofluorescence.C:Autofluorescence of a patient in the advanced stage.Very low autofluorescence with a clear boundary can be seen in the macular area,surrounded by large patches of low autofluorescence.Part of the yellow spots are spot-like low fluorescence.
5例(10眼)Stargardt病初期患者,F(xiàn)FA中可清楚看到黃斑區(qū)色素上皮的萎縮、脫色素,可見黃斑區(qū)小范圍的斑駁狀透見熒光及部分斑駁狀熒光遮蔽,合并黃色斑點(diǎn)的患者,黃色斑點(diǎn)處見點(diǎn)狀透見熒光,隨造影過程進(jìn)展點(diǎn)狀高熒光區(qū)熒光減弱(見圖3)。15例(30眼)病變進(jìn)行期患者FFA可見造影早期黃斑區(qū)RPE及脈絡(luò)膜毛細(xì)血管層萎縮呈“牛眼狀”低熒光,其內(nèi)可透見下方的脈絡(luò)膜血管,隨造影過程進(jìn)展,萎縮區(qū)內(nèi)熒光染色呈模糊強(qiáng)熒光,萎縮區(qū)外見一模糊的強(qiáng)熒光環(huán)。合并周邊黃色斑點(diǎn)者,斑點(diǎn)處透見熒光(見圖4)。8例(16眼)病變晚期患者FFA可見后極部萎縮范圍擴(kuò)大,累及視盤附近,視盤附近呈明顯環(huán)形低熒光區(qū),RPE及脈絡(luò)膜萎縮加重,造影早期可透見下方大范圍的脈絡(luò)膜大血管層,未見熒光滲漏。造影中晚期,萎縮范圍內(nèi)熒光染色(見圖5)。
圖3.Stargardt病初期患者眼底熒光血管造影A:造影動脈期,可見視網(wǎng)膜動脈正常充盈,黃斑區(qū)點(diǎn)狀低熒光,周邊斑點(diǎn)處呈點(diǎn)狀高熒光,黃斑區(qū)斑駁的低熒光區(qū)。B:同一患者造影靜脈期,黃斑區(qū)少量點(diǎn)狀透見熒光,周邊斑點(diǎn)處熒光減弱。C:同一患者造影晚期,未見明顯熒光滲漏與著染Figure 3.Fundus fluorescence angiography in the early stage of Stargardt's disease.A:In the arterial phase of angiography,a normal filling of the retinal artery,spot-like low fluorescence in the macular area,spot-like high fluorescence in the surrounding spots,and a mottled low fluorescence area in the macular area.B:In the angiographic vein phase of the same patient,a small amount of spot-like transparent fluorescence is observed in the macular area,and the fluorescence is weakened in the surrounding spots.C:In the late angiography of the same patient,no obvious fluorescence leakage or staining is observed.
圖4.Stargardt病進(jìn)展期患者眼底熒光血管造影A:造影動脈期,可見黃斑區(qū)RPE及脈絡(luò)膜萎縮呈現(xiàn)低熒光,似“牛眼樣”,萎縮區(qū)域周邊圍繞一較弱的強(qiáng)熒光環(huán),周邊斑點(diǎn)呈強(qiáng)熒光。背景熒光減弱呈脈絡(luò)膜湮滅征。B:同一患者造影靜脈期,黃斑區(qū)斑片狀透見熒光,周邊熒光環(huán)減弱。C:同一患者造影晚期,萎縮區(qū)內(nèi)見彌漫染色,未見明顯熒光滲漏Figure 4.Fundus fluorescein angiography in the progressive stage of Stargardt's disease.A:In the arterial phase of angiography,retinal pigment epithelium in the macular area and choroid atrophy present low fluorescence,similar to a "bull's eye";a weak,strong fluorescence ring surrounds the atrophic area,and the surrounding spots show strong fluorescence.The background fluorescence attenuation shows signs of choroid annihilation.B:In the angiography vein phase of the same patient,patchy and transparent fluorescence is observed in the macular area,and the surrounding fluorescence ring is weakened.C:In the late angiography of the same patient,diffuse staining is observed in the atrophic area,but no obvious fluorescence leakage is observed.
圖5.Stargardt病晚期患者眼底熒光血管造影A:造影動脈期,可見黃斑區(qū)RPE及脈絡(luò)膜萎縮面積擴(kuò)大,累及視盤,視盤周邊低熒光,萎縮區(qū)內(nèi)可透見脈絡(luò)膜大血管影。B:同一患者造影靜脈期,黃斑區(qū)斑片狀透見熒光及點(diǎn)狀低熒光共存。C:同一患者造影晚期,萎縮區(qū)內(nèi)見彌漫染色,未見明顯熒光滲漏Figure 5.Fundus fluorescein angiography in the advanced stage of Stargardt's disease.A:In the arterial phase of angiography,retinal pigment epithelium in the macular area and choroidal atrophy area has expanded,involving the optic disc,low fluorescence around the optic disc,and the choroidal great vessel shadow can be seen in the atrophic area.B:In the angiography vein phase of the same patient,the coexistence of patchy,transparent fluorescence and spotty low fluorescence in the macular area can be seen.C:In the late angiography of the same patient,diffuse staining is observed in the atrophic area,but no obvious fluorescence leakage is observed.
5例(10眼)Stargardt病初期患者OCT顯示黃斑區(qū)小范圍的光感受器層連續(xù)性中斷,RPE層脂褐質(zhì)堆積,呈點(diǎn)狀高反光,厚度不一,脈絡(luò)膜反光無明顯異常(見圖6A)。15例(30眼)病變進(jìn)行期患者黃斑區(qū)光感受器層破壞范圍擴(kuò)大,越靠近中心凹處光感受器層及外界膜逐漸反光減弱,中斷消失,外核層變薄,中心凹處視網(wǎng)膜厚度變薄,RPE層可見脂褐質(zhì)堆積,厚薄不均,部分脈絡(luò)膜層毛細(xì)血管萎縮(見圖6B)。8例(16眼)病變晚期患者可見黃斑中心凹神經(jīng)上皮層完全萎縮、缺失,中心凹周圍神經(jīng)上皮層變薄,光感受器不同程度萎縮、消失,RPE層不同程度萎縮,反光減弱,脈絡(luò)膜層毛細(xì)血管萎縮(見圖6C)。OCT對于周邊黃色斑點(diǎn)部位的掃描,可見黃色斑點(diǎn)RPE層面上高反射物質(zhì)的點(diǎn)狀堆積(見圖6D)。
圖6.Stargardt病患者OCT影像A:初期患者黃斑OCT掃描,可見黃斑中心凹變薄,光感受器層連續(xù)性中斷,RPE層點(diǎn)狀高反光,脈絡(luò)膜反光無明顯異常。B:進(jìn)行期患者黃斑OCT掃描,中心凹處光感受器層及外界膜逐漸反光減弱,中斷消失,外核層變薄,中心凹處視網(wǎng)膜厚度變薄。C:晚期患者眼底黃斑OCT掃描,中心凹周圍神經(jīng)上皮層變薄,光感受器層明顯萎縮消失,RPE層萎縮,反光減弱,脈絡(luò)膜層毛細(xì)血管萎縮。D:周邊黃色斑點(diǎn)處OCT掃描,可見RPE層面上點(diǎn)狀高反色點(diǎn)Figure 6.OCT images of Stargardt's disease.A:OCT scan of a patient in the early stage shows thinning of the macular fovea,discontinuity of the photoreceptor layer,high specular reflection of the RPE layer,and no obvious abnormality of choroidal reflection.B:OCT scan of a patient in the progressive stage shows that the photoreceptor layer and the external membrane in the fovea have gradually decreased reflection,interruption disappears,the outer nuclear layer becomes thinner,and the retinal thickness in the fovea becomes thinner.C:OCT scan of a patient in the advanced stage shows thinning of the cortical layer of the nerve around the fovea,obvious atrophy of the photoreceptor layer,atrophy of the RPE layer,decreased reflection,and atrophy of the capillaries in the choroid layer.D:OCT scan of the surrounding yellow spots shows pointy-like high reverse spots on the RPE plane.OCT,optical coherence tomography;RPE,retinal pigment epithelium.
5例(10眼)Stargardt病初期患者炫彩成像可見眼底炫彩成像基本正常,未見明顯萎縮灶,但由于色素分布改變,后極部可見大量散片狀暗綠色低反射信號區(qū)(見圖7A)。15例(30眼)病變進(jìn)行期患者可在黃斑區(qū)見一明顯的萎縮區(qū)域呈亮黃色高反射信號區(qū),其中散在大量散片狀低反射信號(見圖7B)。8例(16眼)血管弓內(nèi)可見彌漫性黃色高反射信號區(qū),其中可見大量散片狀亮綠色高反射信號,黃斑區(qū)可見較大面積萎縮灶形成的局限性暗紅色低反射信號區(qū)(見圖7C)。
圖7.不同病變階段Stargardt病患者眼底炫彩影像A:Stargardt病初期患者可見眼底炫彩成像基本正常,由于色素分布改變,后極部可見大量散片狀暗綠色低反射信號區(qū)。B:病變進(jìn)行期患者可在黃斑區(qū)見一明顯的萎縮區(qū)域呈亮黃色高反射信號區(qū),其中散在大量散片狀低反射信號。C:血管弓內(nèi)可見彌漫性黃色高反射信號區(qū),其中可見大量散片狀亮綠色高反射信號Figure 7.Multicolor fundus imaging in Stargardt's disease at different stages of the disease.A:Multicolor imaging of a patient in the early stage of Stargardt's disease shows that the multicolor image is basically normal.Due to the change in pigment distribution,a large number of scattered dark green and low reflective signal areas can be seen in the posterior pole.B:Multicolor imaging of a patient in the progressive stage of Stargardt's disease shows a distinct atrophic area in the macula with a bright yellow area of highly reflective signals scattered in numerous patchy areas of low reflective signals.C:Diffuse yellow hyperreflectant areas are seen in the vascular arch,in which numerous,scattered bright green hyperreflectant signals are seen.
對Stargardt病初期、進(jìn)展期、晚期患者OCTA掃描的視網(wǎng)膜淺層血管、視網(wǎng)膜深層血管、脈絡(luò)膜血管進(jìn)行對比觀察。視網(wǎng)膜淺層血管(見圖8─10A)在病變各個階段血管形態(tài)未見明顯異常,但血管密度呈減少趨勢,尤其在晚期患者,血管密度明顯減少。同時,由于黃斑萎縮的擴(kuò)大,淺層血管中央的無血管區(qū)面積相應(yīng)擴(kuò)大。視網(wǎng)膜深層血管(見圖8─10B)在病變處于初期階段,血管變化不明顯,進(jìn)入進(jìn)展期和晚期階段時,視網(wǎng)膜深層血管萎縮明顯,同時因伴隨RPE萎縮,此時的OCTA影像可見下方的脈絡(luò)膜血管影像,隨病變進(jìn)展,透見脈絡(luò)膜的血管范圍擴(kuò)大,同時透見的血管更為粗大。脈絡(luò)膜血管(見圖8─10C)在病變初期時損傷不明顯,血管密度均勻。發(fā)展至進(jìn)展期和晚期時,脈絡(luò)膜毛細(xì)血管萎縮明顯,顯露出更為粗大的脈絡(luò)膜血管。
圖8.不同病變階段Stargardt病患者視網(wǎng)膜淺層血管OCTA影像A:初期;B:進(jìn)行期;C:晚期。各個階段血管形態(tài)未見明顯異常,在晚期患者,血管密度明顯減少。由于黃斑萎縮的擴(kuò)大,淺層血管中央的無血管區(qū)面積相應(yīng)擴(kuò)大Figure 8.OCT angiography of superficial retinal blood vessels in Stargardt patients's at different stages of the disease.A:Early stage.B:Progressive stage.C:Advanced stage.No obvious abnormalities in vascular morphology at all stages,and the vascular density is significantly reduced in advanced patients.Due to the enlargement of macular atrophy,the area of the nonvascular central zone of the superficial vessels is enlarged accordingly.
Stargardt病是一種常見的雙眼對稱性遺傳性黃斑營養(yǎng)不良。其病理過程為:初期的RPE層細(xì)胞脂褐質(zhì)堆積,眼底呈現(xiàn)出脂褐質(zhì)堆積的黃色斑點(diǎn),此時尚無或有輕度的RPE及脈絡(luò)膜血管損傷。由于脂褐質(zhì)具有毒性,隨著病變的進(jìn)展,堆積過多的脂褐質(zhì)導(dǎo)致RPE層細(xì)胞功能障礙或死亡,最終導(dǎo)致RPE開始萎縮,與之密切相關(guān)的光感受器層、脈絡(luò)膜毛細(xì)血管層也開始出現(xiàn)損傷。隨著病變繼續(xù)進(jìn)展,在更大范圍及更深層次上引發(fā)光感受器受損、萎縮及視網(wǎng)膜脈絡(luò)膜萎縮。在這一病理變化過程中,不同的眼底影像檢查手段的聯(lián)合應(yīng)用在疾病的診斷、病理機(jī)制的研究及視網(wǎng)膜功能的變化、病情的發(fā)展等觀察中發(fā)揮重要作用,而不同的影像技術(shù)對Stargardt病的研究又有著不同的側(cè)重點(diǎn)。
圖9.不同病變階段Stargardt病患者視網(wǎng)膜深層血管OCTA影像A:初期;B:進(jìn)行期;C:晚期。初期階段,血管變化不明顯,進(jìn)入進(jìn)展期和晚期階段時,視網(wǎng)膜深層血管萎縮明顯,同時因伴隨RPE萎縮,此時的OCTA影像可見下方的脈絡(luò)膜血管影像Figure 9.OCT angiography of the deep retinal blood flow in Stargardt's patients at different stages of the disease.A:Early stage.B:Progressive stage.C:Advanced stage.In the early stage,the changes in blood vessels are not obvious,but in the advanced and late stages,the atrophy of deep retinal vessels is obvious,and the OCTA images at this time show the underlying choroidal vessels due to the accompanying atrophy of the RPE.
圖10.不同病變階段Stargardt病患者脈絡(luò)膜血管OCTA影像A:初期;B:進(jìn)行期;C:晚期。病變初期時損傷不明顯,血管密度均勻。發(fā)展至進(jìn)展期和晚期時,脈絡(luò)膜毛細(xì)血管萎縮明顯,顯露更為粗大的脈絡(luò)膜血管Figure 10.OCT angiography of choroidal vessels in Stargardt's patients at different stages of the disease.A:Early stage.B:Progressive stage.C:Advanced stage.At the initial stage of transformation,the injury is not obvious and the vascular density is uniform.During the progressive and advanced stages of the development,the choroidal capillaries atrophy significantly,revealing more thick choroidal vessels.
眼底彩色照相作為最傳統(tǒng)和直接的眼底檢查手段,可以直觀反映Stargardt病的黃斑區(qū)色素紊亂程度、黃斑區(qū)萎縮灶的范圍大小,以及周邊黃色斑點(diǎn)的沉著。但對于RPE、脈絡(luò)膜萎縮的精細(xì)辨別能力相對有限,無法明確判斷RPE的功能狀態(tài),對脈絡(luò)膜萎縮的判斷也需在病變達(dá)到一定程度后才能體現(xiàn)。相對于傳統(tǒng)的眼底彩照,炫彩成像通過多波長的組合,可用更好的對比度和層次感顯示出萎縮的細(xì)胞和范圍。
眼底自發(fā)熒光作為一種直接檢測RPE細(xì)胞功能的檢查在Stargardt病的診斷及病情進(jìn)展的監(jiān)測中體現(xiàn)了獨(dú)特的價值。一方面,F(xiàn)AF能清楚直觀地顯示黃斑區(qū)萎縮病灶的大小,另一方面也可以通過自發(fā)熒光的高低變化提示RPE的受損情況。在本組病例中,患者出現(xiàn)黃斑區(qū)輕度的低自發(fā)熒光,證實此處的RPE已經(jīng)被破壞,而低自發(fā)熒光區(qū)域周圍的高自發(fā)熒光環(huán)則提示此處的RPE細(xì)胞正在受到破壞,脂褐質(zhì)存留,病變進(jìn)展。發(fā)展至晚期患者,中央RPE完全萎縮壞死,呈極低自發(fā)熒光區(qū)域,同時萎縮區(qū)擴(kuò)大至后極部較大區(qū)域;周邊黃色斑點(diǎn)沉著處也由于RPE完全破壞從高自發(fā)熒光轉(zhuǎn)變?yōu)榈妥园l(fā)熒光。
眼底熒光血管造影對Stargardt病的檢查可直接反映視網(wǎng)膜色素上皮層、脈絡(luò)膜血管的損傷程度。隨著Stargardt病的發(fā)展,黃斑區(qū)RPE層萎縮范圍擴(kuò)大,視網(wǎng)膜及脈絡(luò)膜毛細(xì)血管繼發(fā)進(jìn)行性萎縮,可見黃斑區(qū)橢圓形病灶范圍擴(kuò)大,呈斑駁狀透見熒光,提示RPE層萎縮。病變發(fā)展至晚期,更大面積及更深層次的萎縮,致使脈絡(luò)膜大血管層可見。相對于自發(fā)熒光,除可以顯示病變面積、程度外,更能提供病變過程中的血管信息。
OCT相對于上述影像檢查手段,提供了斷層眼底的影像信息,能精準(zhǔn)、清楚地顯示Stargardt病患者黃斑區(qū)視網(wǎng)膜神經(jīng)上皮層、光感受器層及RPE層、脈絡(luò)膜層的萎縮程度及范圍,并可有效測量黃斑中心凹厚度,定量評估患者視力損害程度。本組病例的觀察結(jié)果與文獻(xiàn)報道一致:隨病變進(jìn)展,中心凹周圍神經(jīng)上皮層變薄,光感受器不同程度萎縮、消失,RPE層不同程度萎縮,反光減弱,脈絡(luò)膜層毛細(xì)血管萎縮,從層次的深度和范圍的廣度都體現(xiàn)了病變的發(fā)展。同時,OCT對于周邊黃色斑點(diǎn)部位的掃描,顯示了黃色斑點(diǎn)的本質(zhì)為RPE層面上脂褐質(zhì)堆積,從臨床的角度提供了該病變的病理機(jī)制的佐證。
血流成像OCT作為一種新型的無創(chuàng)檢查設(shè)備,也為我們提供了對Stargardt病的新觀察手段。從本組病例中我們觀察到隨著病變的進(jìn)展,各層次血管密度呈減少趨勢。由于色素上皮層的萎縮,當(dāng)掃描視網(wǎng)膜深層血管時,透見了下方的脈絡(luò)膜血管,隨著萎縮加重,透見的脈絡(luò)膜血管的范圍擴(kuò)大,所見的脈絡(luò)膜血管也逐漸粗大,證實脈絡(luò)膜毛細(xì)血管層也隨之萎縮。當(dāng)直接掃描脈絡(luò)膜血管層面的時候,更直接地顯示出脈絡(luò)膜血管不斷萎縮的趨勢。
通過對本組病例的觀察,不同的眼科影像技術(shù)在Stargardt病中的表現(xiàn)有各自特點(diǎn),而各影像技術(shù)在各臨床階段Stargardt病中的表現(xiàn)各不相同,通過眼科各影像技術(shù)在病變演變過程中的表現(xiàn),為臨床醫(yī)師提供了更多角度的追蹤隨訪、病情評估的影像手段。
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張麗珠:參與選題、設(shè)計、資料分析、論文撰寫。黎鏵:參與選題、資料分析。馬銀燕:參與資料收集、整理。李娟娟:參與選題、設(shè)計和資料分析