儿童近视屈光度和眼轴、角膜屈光度的测定分析

目的 探讨儿童近视眼屈光力与眼轴、角膜屈光度相关性程度.方法 对88例(176只限)的儿童近视眼患者,应用IOL-Master分别测量角膜屈光力、前房深度和眼轴等数据,采用SPSS 13.0统计软件进行相关性及回归分析.结果 随着近视度数的加深,眼轴长度和前房深度明显增长.正视组、轻度近视组和中度近视组间角膜曲率(K1、K2)无明显差异,但高度近视组的角膜曲率明显升高.屈光力与眼轴、角膜屈光力的回归方程为直线回归方程DE=81.915-1.953AL-0.569K1-0.28K2.结论 儿童近视眼眼轴延长是发病的主要因素,角膜屈光力作用较小.     

青少年近视眼屈光度与角膜屈光力的相关性研究

目的 研究青少年近视眼屈光度与角膜屈光力的相关性。方法 使用角膜地形图仪和角膜曲率仪对年龄在8～22岁的近视患者,336例共672只眼的屈光度和角膜屈光力进行测定分析。结果 青少年中、低度近视眼垂直径角膜屈光力明显大于水平径角膜屈光力(P<0.001),垂直径角膜屈光力与屈光度呈正相关,并且随近视屈光度增加有明显增高的趋势(P<0.05);而在高度近视眼与中度近视眼组之间,垂直角膜屈光力的增加无显著差异(P>0.05)。结论 垂直径角膜屈光力的增高是青少年中、低度近视眼形成的主要原因。     

超高度近视眼的度数与眼轴相关系数研究

目的探讨超高度近视眼度数与眼轴的相关程度.方法近视球镜当量＞10.00D的超高度近视眼25例45眼,进行A超、角膜地形图检查,分别测量眼轴和角膜屈光力,应用SPSS统计软件包分析近视球镜当量与眼轴及角膜屈光力的关系.结果平均球镜当量为12.8±3.30D,平均眼轴为27.69±1.51mm,平均角膜屈光力为44.04±1.41D.超高度近视眼的度数与眼轴长度的回归方程为SE=-32.69±1.64×Axis(p＜0.01).结论超高度近视眼的度数主要取决于眼轴长度,眼轴延长1毫米,屈光度增加约1.64D.     

近视眼角膜厚度与角膜屈光力的关系

目的探讨近视眼角膜厚度与角膜屈光力的关系及其临床意义。方法对231例462只近视眼作角膜厚度超声测量和角膜屈光力测定。结果近视程度与角膜平均屈光力和角膜厚度均无显著关系，P＞0．05；角膜厚度与角膜屈光力有显著负相关性，P＜0．01；角膜厚度向周边递增与角膜屈光力无显著关系，P＞0．05。结论角膜厚度随角膜屈光力增加而变薄，依据角膜中央厚度测量值行放射状角膜切开术更具优越性。     

近视眼的眼轴与角膜屈光力相关研究

近视眼的眼轴与角膜屈光力相关研究杜连娟孟祥毓北京煤炭总医院眼科（１０００２８）陈明王悦芬①中国医大第一医院眼科（１１０００１）近视眼患者的屈光度与眼轴长密切相关。眼轴越长，屈光度数越大。Ｓｏｒｓｂｙ认为屈光异常是由于眼轴长与角膜屈光力的关系紊乱而产生...     

儿童屈光不正与各屈光参数关系

目的：研究眼轴、角膜屈光力、晶状体屈光力与儿童屈光不正的关系。

方法：通过睫状肌麻痹检影验光及光学生物测量仪(IOL-Master)获得44例88眼的屈光不正度数、眼轴、角膜屈光力、前房深度等参数,经计算得到晶状体度数。按屈光不正度数分为远视组、正视组、近视组,直线相关与回归比较年龄和屈光不正与各屈光参数之间的关系。

结果：受试者44例88眼,平均年龄9.04±2.39岁,等效球镜(SE)-3.50～+8.75D; 远视组眼轴比近视正视组短(P<0.05),远视组晶状体屈光力明显低于近视正视组(P<0.05),三组间角膜屈光力和前房深度无明显差别。本研究发现年龄与等效球镜(SE)之间成负相关; 眼轴与年龄成正相关; 年龄与晶状体屈光力成正相关; SE与眼轴成负相关; SE与晶状体屈光力有负相关关系。

结论：儿童随年龄增长,SE向近视发展,眼轴变长,晶状体屈光力增强; SE越偏远视,眼轴越短、晶状体屈光力越弱。     

青少年近视度与眼轴长度及角膜屈光力的测定分析

目的分析青少年近视程度与角膜屈光力、眼轴长度的相互关系.方法随机抽取某中学近视学生165人309眼,经托吡卡胺扩瞳验光后按等效屈光度＜-3.00D;≥-3.00D～＜-6.00D;≥-6.00D分为低、中、高度近视组,用眼科A超仪(美国Sonomed)测量眼轴长度(每眼5次),用电脑验光仪(Topcon)测量角膜屈光力(每眼3次),取平均值作统计学分析.结果309眼平均眼轴长为24.61±1.60mm,低度组为24.05±1.69mm,中度组为24.37±0.77 mm,高度组为26.40±0.91 mm;垂直径角膜屈光力平均为44.12±1.41D,低度组为43.77±1.50D,中度组为44.72±1.36D,高度组为44.03±0.81D;水平径角膜屈光力平均为43.19±1.28D,低度组为42.94±1.35D,中度组为43.67±1.30D,高度组为43.22±0.81D.其中低度组与中度组眼轴差异无显著性(P＞0.05),角膜屈光力(垂直径和水平径)差异有显著意义(P＜0.01);而中度组与高度组眼轴差异有显著意义(P＜0.01),角膜屈光力(垂直径和水平径)差异有统计学意义(P＜0.05).结论在青少年近视眼中,眼轴变长是近视、尤其是高度近视屈光度增加的主要原因,而在中度近视眼中,角膜屈光力对近视的影响比眼轴长度似乎更大.     

近视眼眼轴及角膜表面形态的测定分析

目的分析近视眼眼轴和角膜表面形态改变的相互关系。方法175例327眼近视，分为低中度、高度和超高度3组，用眼科A／B超仪测量每只眼轴长；用角膜地形图仪检测角膜表面形态，所测数据作组间及相互间比较，统计学分析。结果327眼平均眼轴长为26．46±1.71mm，低中度组为25.08±0.94mm，高度组为26.06±0.83mm，超高度组为28.02±1．50mm，组间差异有显著性意义（P＜0.01）；角膜表面规则性系数（SRI）值为0．28±0．27，角膜表面非对称性系数（SAI）值为0．96±0．53，平均角膜屈光力（ACP）值为43.91±1．42D，角膜表面散光（CYL）值为1．92±0．90D，其中CYL值组间差异有显著性意义，其余各参数组间无显著性差异（P＞0.05）。眼轴值与CYL值呈正相关。结论近视眼眼轴较正视眼眼轴长，随着近视屈光度的增大，角膜非对称性加大，角膜散光也增大，而角膜屈光力无明显改变。近视眼眼轴变长是屈光度增加的主要原因，比角膜屈光力的改变更具决定意义。     

放射状角膜切开术机理的临床分析—兼评国产宝石刀的性能和应…

应用国产ＲＫ－１型双丸可调宝石刀，作了５０只－２．００－１４．００Ｄ近视眼的放射状角膜切开术。通过手术前后角膜屈光力和眼轴长度的检测，证实ＲＫ手术矫正近视的原理是，放射状切开降低了旁中央区外角膜的张力强度，使有膜中央区变平，角膜屈光力降低，而眼轴长度无明显改变。着重论证了膜旁中央切割深度对降低角膜屈光力的关键作用；并认为对高度近视眼周边部角膜切口加深和对矫正不足眼行二次手术均非明智之举。对国产宝石     

儿童近视眼的眼轴与角膜屈光力测定分析

近视眼儿童的角膜屈光力、眼轴长度与近视程度有密切关系。精确地测定角膜屈光力及眼轴长度,对儿童屈光不正治疗方法的选择及预测具有指导性意义。材料和方法1对象　163例(320只眼)近视眼均为我科特殊检查室1994年2月～1998年5月有原始记录者,男性92例(182只眼),女性71例(138只眼)。年龄7～11岁,平均10岁。根据屈光程度分为4组:轻度组(-025Ｄ～-300Ｄ)224只眼,中度组(-325Ｄ～-600Ｄ)64只眼,高度组(-625Ｄ～-1000Ｄ)27只眼,重度组(-1025Ｄ～-1400Ｄ)5只眼。2方法　(1)1%阿托品眼药水每天3次连滴3天,散瞳验光确定屈光程度。(2)用美国产ＳＯＮ…     

青少年单纯性近视眼屈光度与角膜曲率及眼轴的相关性

目的探讨青少年单纯性近视眼屈光度与角膜曲率及眼轴的关系。方法对单纯性近视277例536只眼,测量其角膜水平及垂直曲率,并按年龄、屈光度分组,对各组角膜曲率及眼轴长度进行统计学分析。结果各组角膜水平及垂直曲率比较,差异有显著性(P<0.05)。不同年龄两组间的角膜曲率和眼轴长度比较,差异无显著性(P>0.05)。不同屈光度两组比较,角膜曲率差异有显著性(P<0.05),眼轴长度差异有非常显著性(P<0.01)。多元线性回归和相关分析显示眼球轴长增加是单纯性近视眼形成的主要因素。角膜水平曲率与垂直曲率呈正相关,角膜曲率与眼轴长度呈负相关。结论青少年单纯性近视的屈光度与角膜曲率及眼轴长度密切相关,且眼轴长度是单纯性近视眼形成的主要因素。     

近视屈光度数与角膜屈光力和非球面系数的相关性

目的：对不同近视屈光状态下人眼角膜总屈光力、后表面屈光力、眼轴、角膜非球面参数 Q 值、中央角膜厚度（central cornea thickness, CCT）及眼压进行测量,并探讨近视度数与上述相关参数的关系。 方法：近视患者138例138眼（所有患者选择右眼进行分析）,根据综合验光仪测量的近视度数,患者分为三组：低度近视组（-1.00D～-3.00D）,中度近视组（-3.25D～-6.00D）,高度近视组（〉-6.00D）。各眼使用Pentacam眼前节分析仪（德国,Oculus公司）进行检测,获得角膜总屈光力和后表面屈光力以及Q值,使用非接触式眼压测量仪（日本Canon公司）测量眼压,使用 A 超测量仪（美国Tomey公司AL-3000）测量中央角膜厚度（CCT）和眼轴长度。数据采用Pearson相关性分析、单因素方差分析进行处理。 结果：近视度数与眼轴呈负相关（r=-0.682, P〈0.001）,与角膜屈光力无相关性（r=0.009, P=0.925）,眼轴与角膜屈光力呈负相关（r=-0.554, P〈0.001）。近视度数与Q值呈正相关（r=0.674, P〈0.001）,Q值与眼压成呈负相关（ r=-0.375, P=0.01）。近视度数与CCT及眼压无相关性（ r=-0.138, P=0.141;r=-0.121, P=0.157）。 结论：角膜屈光力在近视发展过程中有正视化作用,Q值与近视度数及眼压的相关关系对指导角膜屈光手术有临床意义。     

New formula to calculate corneal power after refractive surgery

PURPOSE: To assess the validity of intraocular lens (IOL) power calculations utilizing a theoretical variable refractive index correlated to axial length after myopic photorefractive keratectomy (PRK) in a clinical simulation and in patients who underwent cataract surgery after PRK for myopia. METHODS: Our study included 374 eyes of 300 patients who had PRK for myopia (-2.00 to -12.00 D, mean -4.83 +/- 2.57 D), divided into three groups: Group I had 44 eyes with small ablation zones of 5 to 5.5 mm; Group II had 49 eyes with large ablation zones of 6 to 7 mm; Group III was the control group of 281 eyes (201 patients; 87 males and 114 females) with small and large ablation zones. PRK was performed using the Aesculap-Meditec MEL 60/94 and MEL 70 lasers, and the corneal power was acquired by corneal topography (EyeSys 2000) and a Nidek KM-800 keratometer. RESULTS: There was a higher correlation between corneal power and both the change in refraction and axial length when calculated using keratometric measurements. IOL power calculated using keratometric postoperative PRK power was underestimated. The difference between the mean calculated and actual IOL power for emmetropia was 4.30 +/- 2.34 D. A theoretical variable refractive index (obtained from eyes treated with large PRK ablation zones) that correlated with axial length provided the correct keratometric postoperative PRK power: difference between mean calculated and mean actual IOL power was 0.42 +/- 1.23 D. CONCLUSIONS: We propose a theoretical variable refractive index that is correlated to axial length. Utilizing this keratometric correct power, we calculated IOL power similar to that for emmetropia.     

近视的眼轴测量分析

测量并分析近视的眼轴。方法应用ＤＧＨ－４０００型眼用Ａ超随机测量１９－５３岁４４２例近视的眼轴。结果男性眼轴长于女性，年龄，眼别与眼轴无明显关系。在不同屈光度组之间，眼轴的差异非常显著，当近高屈光度９Ｄ时，屈光度敏增加１Ｄ，眼轴增长约０．３２４ｍｍ。     

降低远视离焦对儿童近视发展的影响

目的：探讨降低远视光学离焦是否能减缓儿童近视的发展。方法对同校同级同班的32名近视性屈光不正的9岁儿童,分为两组,甲组配戴普通非球面镜片,乙组配戴抗远视离焦的视特保镜片,每3月进行一次屈光检查,包括：远近视力、矫正视力、眼轴、角膜曲率测量、中心屈光值测量及周边屈光值测量,比较每年眼轴增长的毫米（mm）数及近视度数的增加量,观察三年,进行统计学分析。结果配戴抗远视离焦的视特保镜片在减少儿童近视屈光度增加、减缓眼轴增长方面与普通非球面镜片相比,有统计学意义差异（ P＜0.05）。但在角膜屈光力（Sim K值）方面,二者没有统计学意义（ P＜0.05）。结论降低远视性光学离焦可以延缓近视进展,降低眼轴增长速度,但不能改变角膜曲率,近视性屈光不正儿童可以通过配戴降低远视光学离焦的视特保镜片来减缓近视的发展。     

Optic disc oval ness,refractive error and axial length of Hong Kong Chinese

Myopic crescent, refractive error and axial length were previously investigated in Hong Kong Chinese subjects. The myopic crescent was found to correlate with axial length and myopic refraction. In this study, three groups of Hong Kong Chinese with different degrees of myopia were assessed for optic disc ovalness, refractive error and axial length. The axial length was significantly correlated with the degree of myopia, indicating that the myopia was axial in nature. The regression line shows that 0.44 mm of axial elongation would give about one dioptre of increase in myopia. The elliptical ratio of the optic disc was defined as the maximal disc diameter divided by the minimal disc diameter. All three groups showed an oval disc with vertical axis greater and an increased ovalness for the high myopic group with an elliptical ratio from 1.11 in low myopia to 1.29 in high myopia. There is a small amount (about four degrees) of temporal rotation of this vertical oval orientation, which is independent of the amount of myopia. This result shows an association between axial elongation of the globe and optic disc ovalness, in addition to the previously described temporal myopic crescent. Therefore, in myopic subjects, a vertically oval disc may be associated with a myopic refraction rather than glaucoma.     

Distribution of axial, corneal, and combined ametropia in a refractive surgery unit

PURPOSE: To group eyes in our refractive surgery unit on the basis of the origin of their ametropia and to assess the percentage of eyes in the different groups. METHODS: Refractive parameters and the axial eye length (AL) of 131 eyes of 131 persons with different refraction were measured. The eyes were initially classified into five groups on the basis of the grade of their ametropia: hypermetropic (> +0.5 D, n = 35), emmetropic (between +/- 0.5 D, n = 24), low myopic (between -0.75 and -4.0 D, n = 24), medium myopic (between -4.25 and -8.0 D, n = 24), and high myopic (over -8.0 D, n = 24). Then a classification scheme was made to group the origin of the ametropia on the basis of AL and corneal refractive power. RESULTS: In the hypermetropic group pure corneal origin was found in 8.6%, pure axial origin in 62.8%, and combined origin in 28.6% of the eyes. In the low myopic group these values were 20.9%, 29.2%, and 45.8%, respectively. In the medium and high myopic groups no pure corneal myopia was found, while axial myopia was found in 16.7% and combined myopia in 83.3% of the eyes. CONCLUSIONS: With the help of the classification scheme, an objective decision could be made as to whether the ametropia of a particular eye had axial, corneal, or mixed origin. The most interesting result was that in 83% of medium and high myopic eyes not only AL but also corneal refractive power contributed to the refractive error instead of the eyes being purely axially myopic.     

不同类型高度病理性屈光参差屈光要素分析

目的分析不同类型高度病理性屈光参差同例双眼的屈光要素构成差异,探索影响屈光状态的主要因素、相互关系。方法收集136例等效球镜>3.00D的单纯近视性、远视性屈光参差,复性近视性、远视性屈光参差患者的临床资料,按屈光度数不同分为高屈光眼组和低屈光眼组;按屈光状态不同分为近视性屈光参差组(104例)和远视性屈光参差组(32例)。对所有患者双眼进行角膜地形图检查角膜屈光力,眼部A超检查前房深度、晶状体厚度及眼轴长度,对相关数据进行配对t检验,对各屈光要素与眼球屈光度进行多元线性回归分析。结果角膜屈光力近视性屈光参差组双眼相似率为79.81%,高于远视性屈光参差组的68.75%(P<0.05);前房深度近视性屈光参差组双眼相似率为68.27%,远视性屈光参差组为59.38%,二者差异无统计学意义(P>0.05);晶状体厚度近性视屈光参差组双眼相似率为79.81%,远视性屈光参差组为90.63%,二者差异无统计学意义(P>0.05);眼轴长度近视性屈光参差组双眼相似率为12.50%,远视性屈光参差组为18.75%,相似率均较低(P>0.05)。多元线性回归分析示:近视性屈光参差屈光度数与角膜屈光力、晶状体厚度及眼轴长度呈正相关关系(b=0.836、1.406、2.279,均为P<0.05),与前房深度呈负相关关系(b=-2.051,P<0.05);远视性屈光参差屈光度数与角膜屈光力、晶状体厚度及眼轴长度成负相关关系(b=-0.912、-1.389、-2.318,均为P<0.05),与前房深度无显著相关关系(P>0.05)。结论角膜屈光力及眼轴长度是影响眼球屈光状态的主要因素。前房深度及晶状体厚度在眼纵轴线上的位置对眼球屈光状态的影响不容忽视。     

Corneal power determination after previous corneal refractive surgery for intraocular lens calculation

PURPOSE: To assess the accuracy of different corneal power determination methods in patients who had undergone myopic laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and radial keratotomy (RK). METHODS: The results for 208 eyes of 116 patients who had had corneal refractive surgery (LASIK, PRK, RK) for myopia were analyzed retrospectively. Keratometry measurements, i.e., autokeratometry readings (K(meas)), simulated keratotopography readings (Sim-K), and topographically measured average central corneal power in a 3-mm zone (ACP) were compared with calculated refraction-derived keratometric value. Correction factors based on the difference between measured and calculated keratometric powers were rated. RESULTS: Direct power measurements with standard keratometers and planokeratotopography systems overestimate corneal power after myopic PRK and LASIK. The average K(meas) and K(topo) were significantly greater than the average calculated refraction-derived keratometric values. Corneal power overestimation correlated significantly with the spherical equivalent change after refractive surgery (p < 0.001). After RK, there is no significant correlation of the difference between all measured K values and refraction-derived power with the spherical equivalent change. In these cases, the Sim-K value seems the most accurate among measured keratometric powers. The precision of measurement significantly depends on the parameters of the autokeratometer (i.e., measurement place, number of measurement points, keratometric index of refraction). CONCLUSIONS: To avoid underestimation of intraocular lens power after cataract surgery in the eyes that had previously undergone myopic corneal refractive surgery, the measured corneal power must be corrected. Although correction factors may be calculated for cases after PRK and LASIK, there are no universal and absolutely reliable methods to determine corneal power in these cases. More than one accessible method should be used, and the lowest, most reliable data should be used.