【摘要】 目的：探讨典型视网膜色素变性晚期自发荧光影像与中心视力关系。方法：晚期典型视网膜色素变性37例 ( 70眼 )，采用HRA2共焦激光扫描系统获取眼底自发荧光影像，视野30°，像素1536×1536，瞳孔直径＞6mm，部分患者进行FERG和Humphrey 静态视野检查。结果：根据自发荧光影像表现将所有患者分为4种类型，即完整型、斑驳型、孤岛型和中心低荧光型。不同类型的自发荧光表现出不同的中心视力。结果证实，眼底自发荧光影像改变与中心视力高度相关，自发荧光面积与视力有显著差异(n=57,r=0.385,P＜0.01)，自发荧光面积与年龄有显著差异(n= 57, r= 2.67, P＜0.05)。结论：自发荧光影像对于中心视力的监测和预测具有实际价值。自发荧光变化与中心视力相关，不同的荧光类型视力改变程度不同。尽管视网膜色素变性仍无彻底治愈方法，但保护性治疗是必要的，如抑制细胞凋亡、改善供血以及营养神经元等。
【关键词】 视网膜色素变性 自发荧光 中心视力 晚期
INTRODUCTION
Retinitis pigmentosa (RP) refers to a heterogeneous group of genetically determined retinal degenerations characterized by peripheral photoreceptor dysfunction, affecting rods more than cones. Classical symptoms include nyctalopia and visual field constriction. Classic clinical signs include intraretinal bonespicule pigment, vessel attenuation, and pale discs. Central vision may or may not be involved and may deteriorate at a slower rate than the periphery. Monitoring of central cone function may be of value in predicting retention of central vision.
Autofluorescence (AF)appears abnormal suffering from RP. Absence of AF suggests either blocking of the incident radiation, photoreceptor cell death and retinal pigment epithelium(RPE) atrophy [ 1, 2] or disruption of the vitamin A cycle [ 3,4 ]. This absence of AF associated with the vision.
The main aims of the current study were to evaluate different abnormal AF images associated with central vision in classical RP.
MATERIALS AND METHODS
Materials Thirtyseven patients (70 eyes) with classical RP at advanced stage were observed excluding other no classical RP such as sector RP, Bietti RP, cone dystrophy etc. The factors of dioptric media were got rid of such as cataract or refractive errors etc. Patientsage ranged from 20 to 79 years, with a mean age of 46±15 years including male ( 24 cases ), female ( 13 cases ). All patients had the corrected visual acuity (CVA ) from LP to 0.8. The clinical diagnosis of RP confirmed by fullfield ERGs, abnormal AF and the fundus manifestation under ophthalmoscope.
Some patients underwent automated static perimetry (program 242; Humphrey Field Analyzer; Zeiss Humphrey Systems 720i, Dublin, CA). Flash electroretinogram (FERG) were performed according to the Internation Society for Clinical Electrophysiology of Vision (ISCEV) standard.
Methds AF imaging was performed using a Heidelberg Retina Angiograph 2 ( HRA2) scanning laser system with the field 30°, the pixels 1536×1536 and pupil diameters ＞6mm. Optical master wavelength is 488nm and blue light excites AF of the fundus using fluorescein angiography (FA) mode without fluorescein injected. Overlay Draw Region function were performed to measure the AF areas.
Statistical Analysis Analysis range of AF is between up and down hemal arch. SPSS 11.5 software package was used for the statistical analysis.
Figure 1 Intact pattern of AF image. It showed the low density AF outside of the hemal arch with a parafoveal ring of high density AF（略）
Figure 2 Patchy pattern of AF image. It showed the patchy AF and in extent AF was similar to intact pattern（略）
Figure 3 Solitary island pattern of AF image. It showed a small high density AF（略）
Figure 4 Central hypofluorescence pattern. It showed a lowe density AF of the macula with the relic（略）
RESULTS
Patterns of AF All patients were classified as four types according to their manifestation of AF.
Intact pattern between up and down hemal arch the density of AF look like normal but it is abnormal outside of the hemal arch that showed lower density AF or absence completely. Sometimes a ring high density AF may be seen (Figure 1).
Patchy Pattern In extent AF might be similar to intact pattern but the density is nonuniform as though "patchy" or "geographic" pattern, its border is irregular. Even though extent of patchy AF exceed hemal arch sometimes, it shows a small remain high signal and the fovea might be effected or not (Figure 2).
Solitary Island Pattern Between up and down hemal arch AF showed extensive low signal or hypofluorescence but there was a small schistic hyperfluorescence center in fovea. It looks like a "solitary island" and fovea is normal (Figure 3).
Central Hypofluorescence Pattern In the end macula would be involved for classical RP. Macula showed extensive low density AF at fovea especially. Someone might display socalled ring pattern and center in the fovea with a low density AF encompassing a high density ring AF. It is important that the low density AF of the fovea was different from the low density AF of the normal fovea,it expands obviously and appears a clear border. For severe cases entire macula only showed a few relic AF (Figure 4).
AF and Vision In total 70 eyes, intact patterns comprised 17 eyes (24%) and patients had the best corrected visual acuity (BCVA) from 0.3 to 0.8 and 4 eyes displayed the ring AF patterns. Eleven eyes had the BCVA above 0.5. Patchy patterns included 8 eyes (11%) and had BCVA from HM to 0.4 and the changes of vision depend on if the fovea was damaged. Solitary island patterns included 14 eyes(20%)and BCVA was from 0.1 to 0.8 including that 9 eyes had the BCVA above 0.5.Thirtyone eyes of central hypofluorescence patterns (44%) were observed and their BCVA was from LP to 0.1.
The Correlations Between AF and Vision or Age Correlation test was performed between the central vision and the AF area with SPSS 11.5 for 57 eyes and there is significant correlation.(n=57,r=0.385,P＜0.01 ). The relation between age and AF area is significant (n=57,r=2.67,P＜0.05 ).
It is known to all FERG and Humphrey field of RP were abnormal quite obviously at the advanced stage. Amplitudes of b wave reduce, particularly rod cell responses even extinguish. The visual field showed concentric constriction. However they are not applicable to monitoring of central cone function in predicting retention of central vision. Therefore they are usually used to the clinic diagnosis of RP and are valuable to evaluating the severity of RP.
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