长期配戴角膜接触镜对角膜厚度屈率及表面规则性的影响

目的 :了解长期配戴角膜接触镜对角膜厚度、屈率及表面规则性的影响。方法 :应用Orbscan角膜地形图系统检测 3 5例 (64只眼 )配戴角膜接触镜 5年以上患者的全角膜厚度、前表面角膜屈率及角膜前、后表面高度地形图。 2 0例 (4 0只眼 )正常人为正常对照。采用TMS 1角膜地形图系统的参数评价角膜表面规则性。比较正常人和配戴角膜接触镜 5年以上患者的全角膜厚度、角膜屈率、表面规则指数 (SRI)、表面不对称指数 (SAI)、预测视力(PVA)及角膜地形图图形的差异。结果 :戴镜组病例其配戴角膜接触镜的平均时间为 (13 45± 6 42 )年。与正常对照组相比 ,长期配戴角膜接触镜患者其角膜中央及周边 8个测量区的平均角膜厚度减少 3 0～ 5 0 μm (P <0 0 0 1) ,角膜屈率、最大角膜屈率 (MaxK )及最小角膜屈率 (MinK)明显增加 (P <0 0 1)。两组间角膜散光度无显著性差异。长期配戴角膜接触镜的患者其TSM 1系统参数中的SRI和SAI值较正常人明显增加 (P <0 0 1) ,PVA值无明显改变 (P =0 15 )。应用两种角膜地形图仪检查所得的角膜屈率地形图及角膜高度地形图的彩色编码图形类型 ,两组间无显著性差异。结论 :长期配戴角膜接触镜将导致全角膜厚度减小、角膜屈率增加及角膜表面不规则性增加     

圆锥角膜早期的角膜地形图改变

目的　揭示早期圆锥角膜角膜地形图的特征,为早期诊断此病提供参考。方法　收集了本院门诊拟诊为早期圆锥角膜的患者27例52眼。所有患者均行TMS-1角膜地形图测定。结果　80.77%眼角膜最高屈光度部位在正下方或颞下方,最高屈光度在45D以上,散光在2D以上,所有眼平均最高屈光度在47.56D±5.80D,平均散光5.47D±3.80D;角膜非对称性指数(SAI)及角膜规则性指数(SRI)值大于0.5者分别为94%、98%,SAI值平均为2.6±1.9,SRI值平均为1.67±0.94。结论　早期圆锥角膜的测定须兼顾上述综合参数,SAI及SRI值的变化更敏感。     

人工泪液对干眼症患者眼像差及角膜地形图的影响

目的 观察干眼症患者滴用人工泪液后眼像差和角膜地形图的改变.方法 对18例(30只眼)干眼症患者滴用人工泪液前、用药后即刻和用药10min后进行眼像差和角膜地形图的测量,分析指标为像差均方根值(RMSg),垂直慧差(C7),水平慧差(C8),球差(C12),角膜表面规则性指数(SRI)和角膜表面不对称指数(SAI),采用重复测量方差分析方法 对数据进行分析,以P<0.05认为差异具有统计学意义.结果用药后即刻测得的RMSg、C7、C8、C12、SRI和SAI值较用药前明显下降(P≤0.01),指标在用药10min时仍然维持稳定.结论 人工泪液可以改变干眼症患者角膜表面的不规则性参数,从而通过改变RMSg、C7、C8、C12、SRI和SAI值来改善其光学视觉质量.     

翼状胬肉大小与角膜地形图的相关性研究

目的 :研究翼状胬肉的长度、宽度及胬肉覆盖角膜的面积对角膜表面形态的影响以及术后的改善情况。方法 :对翼状胬肉 33例 ,4 5只眼患者术前进行检影验光及角膜地形图检查 ,术中测量翼状胬肉的宽度及长度 ,对翼状胬肉的宽度、长度及面积与角膜表面规则指数 (SRI)、不对称指数 (SAI)及角膜散光进行相关性研究 ;随访 2 3例 ,2 8只眼翼状胬肉患者进行术后的角膜地形图检查 ,观察各项指标的变化 ,从而找出最好的手术时机。结果 :术前翼状胬肉的长度与角膜散光 (r =0 30 4 ,P=0 0 4 2 ) ,SRI(r =0 4 78,P =0 0 0 1)和SAI(r =0 5 0 7,P <0 0 0 1)具有明显的相关性 ;翼状胬肉的宽度及面积与SRI(r =0 4 90 ,P =0 0 0 1;r =0 5 99,P <0 0 0 1)和SAI(r =0 5 0 8,P <0 0 0 1;r =0 5 83,P <0 0 0 1)有明显的相关性 ;而散光却与SRI及SAI(r=0 2 5 3,P =0 0 93;r=0 2 6 8,P =0 0 75 )无明显的相关性。术后只有角膜散光的改善具有显著性差异 (P =0 0 2 3) ,而SRI及SAI的改善无显著性差异 (P =0 4 2 3;P =0 14 3)。结论 :翼状胬肉的出现、生长及其手术切除对角膜的球面性、规则性以及散光均有影响 ,而有些影响是不能通过手术解除 ,所以本研究建议可适当地提前手术时机     

角膜形态学因素对非接触式眼压计测量值的影响

目的　探讨角膜形态学指标和角膜中央厚度对非接触式眼压计测量值的影响。方法　选择屈光度 -0 75～ -2 5 0 0D的患眼 13 0 8眼 ,使用非接触式眼压计测量眼压 ,计算机辅助角膜地形图仪测量SimK1、SRI和SAI。采用多元线性回归分析的方法综合分析各自变量与眼压测量值之间的线性关系。结果　角膜中央厚度和SimK1与眼压测量值有明显的线性相关关系 (P <0 0 1) ,而SRI和SAI与眼压测量值无明显线性相关 (P >0 0 5 )。结论　近视眼患者角膜中央的规则性 (以SAI为代表 )和对称性 (以SRI为代表 )的变异 ,尚不致影响非接触式眼压计的测量结果。对眼压测量值构成影响的是角膜中央厚度和角膜屈光力 (以SimK1为代表 )。     

不同近视程度及准分子激光屈光术后角膜地形图分析

目的 分析不同近视程度患者的角膜地形图及准分子激光术前、术后角膜地形图的差异,了解不同近视程度及术后角膜表面形态的改变.方法 回顾性分析2004年在我院行准分子激光屈光性手术的159例患者的角膜地形图资料,比较SRI、SAI、CLY等反映角膜表面形态的参数,采用SPSS 13.0统计软件进行统计分析.结果 不同近视程度组间角膜地形图比较示:CYL的差异有统计学意义(P＜0.05),而SRI、SAI各组间没有明显差异P＞0.05);准分子激光屈光性手术前后角膜地形图参数分析示:术后CYL、SRI、SAI均有显著变化(P＜0.01),其差异具有统计学意义.结论 不同程度的近视患者间角膜表面的规则程度、对称性没有显著差异,而散光程度随近视度数增大而有所增加.准分子激光术后角膜规则性、对称性、散光程度均有显著改变,行准分子激光术矫正屈光不正时应更加注重角膜形态的改变,以减少术后视觉质量及光学问题的发生.     

ORK与LASIK术后角膜地形图变化的对比研究

目的:探讨角膜波面像差引导的准分子激光个体化屈光手术(optimized refractive keratectomy-customized ablation,ORK)治疗高度近视患者术后角膜表面规则性和对称性情况。方法:对50例100眼高度近视患者行角膜波面像差引导的准分子激光个体化屈光手术治疗,对同期50例100眼高度近视患者用传统LASIK治疗,观察两组疗效,并采用角膜地形图检查仪测量两组术后6mo的角膜地形图变化[包括角膜曲率,K1,K2,表面非对称指数(surface asym-metry index,SAI),表面规则指数(surface regularity index,SRI)]。结果:与术前比较,两组术后角膜曲率、K1,K2,SAI,SRI降低(均为P<0.05)。ORK组术后6mo SAI,SRI改善优于传统组(均为P<0.05)。结论:角膜波面像差引导的准分子激光个体化屈光手术与传统LASIK比较,角膜波面像差引导的准分子激光个体化屈光手术治疗的患者术后6mo角膜规则性和对称性优于应用传统LASIK治疗的患者。     

正常人角膜前后表面地形及全角膜厚度的研究

目的　了解正常人的角膜前后表面形态及全角膜厚度,为诊断异常角膜提供参考依据。方法　应用Orbscan角膜地形图仪对46例正常人（46只眼）的角膜进行检测,建立其正常参数。结果正常人角膜最薄处为（0.55±0.33）mm,平均位于距视轴（0.90±0.51）mm处。32例（70%）角膜最薄点位于颞下方,11例（24%）位于颞上方,2例(4%)位于鼻下,1例(2%)位于鼻上方。角膜厚度以角膜中央最薄（0.56±0.03）mm,角膜上方最厚（0.64±0.03）mm。模拟角膜屈率（SimK）为（44.24±1.61/43.31±1.66）D,散光度为（0.90±0.41）D。角膜前表面高度地形图的图形中,岛形最多,其次为不完全嵴形。角膜后表面高度地形图的图形中,岛形最多,其次为规则嵴形及不完全嵴形。在前表面角膜屈率地形图的图形中,对称蝴蝶结形最多,其次为椭圆形及不对称蝴蝶结形。在角膜厚度彩色地形图中,椭圆形最多,其次为圆形。结论　了解正常人全角膜厚度、角膜高度形态及角膜前表面角膜屈率地形图将为诊断异常角膜提供依据。Orbscan角膜地形图仪是一种测量角膜地形及全角膜厚度的有用工具,在角膜屈光手术中将具有重要的应用价值。     

圆锥角膜的角膜前后表面形态及厚度检测

目的　了解圆锥角膜的角膜地形图改变。方法　应用Orbscan角膜地形图系统检测 35例 (47只眼 )圆锥角膜患者的角膜 ,对其角膜中心点、锥顶、角膜后表面最高点、角膜屈光度最大点和角膜最薄点的位置、角膜前表面高度、角膜屈光度及角膜厚度 ,以及角膜屈光度和角膜前表面高度的关系进行分析。结果　圆锥角膜锥顶的高度平均为 (0 10 2± 0 0 4 4 )mm ,距角膜中心点的距离为(0 6 86± 0 376 )mm。圆锥角膜锥顶、角膜后表面最高点和角膜屈光度最大点的位置分布以颞下最多 ,其他依次为鼻下、颞上、鼻上 ,最薄点以鼻下方为多 ,其次为颞下。圆锥角膜的角膜曲率为 (6 0 9± 10 4 / 5 3 4± 8 7)D ,角膜中央直径 3mm、5mm内平均屈光度数分别为 (5 7 1± 8 0 )D、(5 0 7± 5 4 )D。圆锥角膜锥顶的高度与此点的屈光度数呈明显的正相关 (r=0 6 97,P <0 0 1) ,与此点的角膜厚度呈负相关 (r=- 0 5 6 3,P <0 0 1)。结论　Orbscan角膜地形图系统可为早期诊断圆锥角膜并提供形态学依据。     

波前引导LASIK术后角膜地形图变化

目的探讨波前引导准分子激光原位角膜磨镶术（laser in situ keratomileusis。LASm）术后角膜前表面地形图的变化。方法比较分析23例（46眼）波前引导LASIK（引导组）和27例（54眼）传统LASIK（传统组）术后不同时期角膜地形图变化。结果2组患者术前角膜平均曲率（K）、角膜散光屈光力（K1—K2）、表面不对称指数（surface asymmetry index,SAI）、表面规则指数（surface regularity index，SRI）均无显著差异（P〉0．05）。2组术后K1—K2减小，SAI明显增加，SRI亦有轻度增加（P〈0．05）。术后6个月引导组与传统组的K、K1—K2、SAI、SRI分别为39．70、0．71、0．15、0．39和39．86、0．85、0．20、0．46。术后6个月传统组SAI高于引导组（P〈0．05）。术后不同时间SRI与术前差值比较．结果显示引导组和传统组均以术后3个月为最高，术后6个月为最低，引导组SRI术后时间变化有统计学意义（P〈0．05）。而引导组与传统组术后不同时间SAI、SRI差值比较差异无统计学意义（P〉0．05）。角膜地形图形态术前引导组与传统组均以不对称领结形为著，分别为50．0％和48．1％．术后不同时间2组均以均匀形为著。但引导组中不规则形所占比例明显高于传统组（P〈0．05）。结论波前引导LASIK术后角膜的规则性和对称性优于传统LASIK，但角膜形态的不规则性明显增加。[眼科新进展2007；27（2）：123-126]     

Corneal surface regularity and the effect of artificial tears in aqueous tear deficiency.

PURPOSE: To evaluate corneal surface regularity and the effect of artificial tears on the regularity of the corneal surface in dry eye. DESIGN: A prospective, clinic-based, case-control study. PARTICIPANTS: A total of 64 eyes of 33 normal subjects and 42 eyes of 22 patients with aqueous tear deficiency were evaluated. METHODS: Indices of the TMS-1 corneal topography instrument (Tomey Technology, Cambridge, MA) were used to evaluate corneal surface regularity and potential visual acuity (PVA) in patients with aqueous tear deficiency dry eye before and after the instillation of artificial tears and in normal subjects. The TMS-1 topographic maps were classified into round, oval, symmetric bow-tie, asymmetric bow-tie, and irregular patterns. MAIN OUTCOME MEASURES: The surface regularity index (SRI), surface asymmetry index (SAI), PVA index, and topographic pattern of the TMS-1 were compared between normal and dry eyes and in dry eyes before and after the instillation of artificial tears. RESULTS: The SRI and SAI were significantly elevated and the PVA was significantly reduced in dry eye patients compared with normal subjects: 0.31+/-0.22, 0.30+/-0.16, and 20/17.89+/-20/3.04, respectively, in normal subjects and 1.28+/-0.73, 1.05+/-1.17, and 20/33.45+/-20/13.99, respectively, in patients with dry eye (P<0.001 for all indices). The average amount of astigmatism was also increased in dry eyes (2.10+/-1.96 prism diopters) compared with normal eyes (1.13+/-0.53 prism diopters, P = 0.02). In dry eyes, the SRI and SAI were positively correlated with corneal fluorescein staining scores (P = 0.005 for SRI and P = 0.016 for SAI). The mean PVA was not significantly different from the mean actual corrected visual acuity. The dry eyes had a significantly lower percentage of symmetric bow-tie patterns and a greater percentage of irregular patterns on topographic maps than normal eyes. After the instillation of artificial tears, the SRI, SAI, and mean astigmatism all decreased significantly (P<0.001 for SRI, P<0.002 for SAI, P = 0.04 for astigmatism) and the PVA improved (P<0.001) in dry eyes. An irregular topographic pattern was observed in 45.24% of dry eyes, and this decreased to 30.95% after the instillation of artificial tears (P<0.005). CONCLUSIONS: Patients with aqueous deficiency have an irregular corneal surface that may contribute to their visual difficulties. The SRI and SAI could be used as objective diagnostic indices for dry eye as well as for evaluating the severity of this disease and the effect of artificial tears. Artificial tears have the secondary benefit of smoothing the corneal surface in dry eye.     

The effect of artificial tears on corneal surface regularity in patients with Sjögren syndrome

PURPOSE: To evaluate the effect of artificial tears on the topographic parameters associated with corneal surface regularity in patients with Sj?gren syndrome. METHODS: A total of 38 eyes of 20 patients with Sj?gren syndrome were evaluated prospectively. The mean age of the patients was 50.5 +/- 15.3 years (range, 28-76). Corneal topography with the Topographic Modeling System (TMS-2, Tomey) was performed before and after the instillation of artificial tears. The surface regularity index (SRI), surface asymmetry index (SAI), potential visual acuity (PVA) and mean astigmatism were compared in dry eyes before and after the instillation of artificial tears. RESULTS: Before the instillation of artificial tears SAI, SRI, PVA and mean antigmatism values were found to be 1.37 +/- 1.47, 0.74 +/- 0.42, 20/30.92 +/- 20/8.12 and 1.53 +/- 1.47 D, respectively. In corneal topography performed after the instillation of artificial tears SAI, SRI, PVA and mean astigmatism values were 0.71 +/- 0.82, 0.43 +/- 0.36, 20/25.92 +/- 20/5.55 and 1.08 +/- 1.18, respectively. When compared statistically, the SRI, SAI, and mean astigmatism all decreased significantly and the PVA improved (p = 0.0001). CONCLUSION: Irregular corneal surface in dry eye patients affects optical quality. The statistically significant improvement observed in SRI and SAI values after the instillation of artificial tears also improves the PVA that is especially related to SRI.     

Effect of artificial tears on corneal surface regularity,contrast sensitivity,and glare disability in dry eyes

OBJECTIVE: To investigate the effects of artificial tears on corneal surface regularity and visual function in dry eyes. DESIGN: Nonrandomized, comparative trial. PARTICIPANTS: Forty patients (40 eyes) with dry eyes with (group 1, n = 15 eyes) or without (group 2, n = 25 eyes) punctate epithelial keratopathy and a normal control group of 20 individuals (20 eyes) with no ocular abnormalities (group 3). METHODS: In both dry and normal eyes, the surface regularity index (SRI), surface asymmetry index (SAI), and potential visual acuity (PVA) were measured by computer-assisted videokeratography (TMS-1; Computed Anatomy, New York, NY). Spatial-contrast sensitivity and glare disability were also measured before and 1 minute after instillation of artificial tears. MAIN OUTCOME MEASURES: Differences in SRI, SAI, PVA, spatial-contrast sensitivity, and glare disability between groups, before instillation of tears, and within groups, after instillation of tears. RESULTS: Compared with group 3, eyes in group 1 had significantly worse SRI, SAI, PVA, and contrast sensitivity (incomplete glare disability data precluded analysis) before instillation of artificial tears. Differences in corneal surface regularity and visual function between groups 2 and 3 were not significant except for a significantly increased glare disability at low spatial frequency (1.5 cycles per degree [cpd]) in group 2. Significant improvement in SRI, SAI, PVA, and contrast sensitivity were observed after instillation of artificial tears in group 1. In groups 2 and 3, the only significant changes were improvement in glare disability at 1.5 cpd and worsening of the SRI, respectively. CONCLUSIONS: Tear film changes in dry eye patients may lead to irregularities on the corneal surfaces, causing glare disability. However, these changes may be too subtle in the early stages of dry eyes to be detected by corneal topography or contrast sensitivity measurements. Significant improvement in SRI, SAI, PVA, and contrast sensitivity were found after instillation of artificial tears in dry eyes with punctate epithelial keratopathy.     

Assessing the severity of keratitis sicca with videokeratoscopic indices

PURPOSE: To determine the correlation between the regularity indices of the Tomey TMS-2N computerized videokeratoscopy (CVK) instrument (Tomey, Waltham, MA) with conventional measures of dry eye symptoms and disease. DESIGN: A retrospective, clinic-based, case-control study. PARTICIPANTS: A total of 16 eyes of 16 asymptomatic normal subjects and 74 eyes of 74 patients with reports of ocular irritation. METHODS: Corneal surface regularity and potential visual acuity indices of the Tomey TMS-2N CVK instrument were evaluated in patients with ocular irritation symptoms and in normal subjects. MAIN OUTCOME MEASURES: The surface regularity index (SRI), surface asymmetry index (SAI), potential visual acuity index (PVA), and irregular astigmatism index (IAI) of the Tomey TMS-2N were compared between normal and dry-eye patients. Severity of dry-eye symptoms was assessed with a validated questionnaire. Schirmer 1 test (without anesthesia), biomicroscopic meibomian gland evaluation with a composite severity score (MGD score), fluorescein tear break-up time (TBUT), and corneal fluorescein staining were performed. The correlations between CVK indices of the Tomey TMS-2N and the symptom severity score, Schirmer 1 test, MGD score, TBUT, and corneal fluorescein staining score were studied. RESULTS: Dry-eye patients had greater mean symptom severity scores, lower Schirmer 1 test scores, greater MGD scores, more rapid TBUT, and greater total corneal fluorescein staining scores (P < 0.001 for all parameters). The SRI, SAI, and IAI were all significantly greater in dry-eye patients than normal subjects. These were 0.46 +/- 0.36 (normal) versus 1.09 +/- 0.76 (dry) for the SRI (P = 0.0017), 0.30 +/- 0.15 (normal) versus 0.90 +/- 1.09 (dry) for the SAI (P = 0.0321), and 0.42 +/- 0.28 (normal) versus 0.56 +/- 0.24 (dry) for the IAI (P = 0.0321). The PVA index was significantly lower in the dry-eye patients (0.89 +/- 0.13) than normal eyes (0.68 +/- 0.23; P = 0.0008). The SRI, SAI, and IAI were positively correlated with total and central corneal fluorescein staining scores (P < 0.00001 for all indices). An SRI (> or =0.80), SAI (> or =0.50), and IAI (> or =0.50) had sensitivities in predicting total corneal fluorescein staining (score > or = 3) of 89%, 69%, and 82%, respectively. The specificity of these indices was 80%, 78%, and 82%, respectively. In all 90 eyes, the mean SRI was greater in subjects older than 50 years (P = 0.012) compared with younger patients, whereas no age effect was noted in the dry-eye patients. The SRI and PVA index showed better correlation with symptoms of blurred vision than the best-corrected visual acuity. CONCLUSIONS: Patients with ocular irritation have an irregular corneal surface that may contribute to their irritation and visual symptoms. Because of their high sensitivity and specificity, the regularity indices of the Tomey TMS-2N have the potential to be used as objective diagnostic indices for dry eye, as well as a means to evaluate the severity of this disease.     

Corneal topographical study of the effect of lacrimal punctum occlusion on corneal surface regularity in dry eye patients.

PURPOSE: To compare topographic indices of surface regularity in dry eye patients and in normal subjects (controls) and to investigate the short-term effect of lacrimal punctal plugs on these indices in dry eye patients. METHODS: The surface regularity index (SRI) and surface asymmetry index (SAI) of the TMS-2 corneal topographic modelling system were used to evaluate corneal surface regularity in 20 eyes of 10 dry eye patients before and after the insertion of Herrick silicon lacrimal plugs (Lacrimedics, Rialto, CA, USA) and in 24 eyes of 12 normal subjects as controls. RESULTS: SRI and SAI were significantly lower in controls than dry eye patients (p=0.00). Median SRI was 1.72 in dry eye patients before punctal occlusion and 0.525 in the control group. Median SAI was 1.305 in dry eye patients and 0.240 in controls. After lacrimal punctal occlusion, Schirmer test results and fluorescein breakup time increased in nine patients and remained the same in one patient. After occlusion, the SRI decreased in 9 eyes, and increased in 11 (p=0.970); SAI decreased in 13 eyes and increased in 7 (p=0.135). CONCLUSIONS: No significant change in topographic indices of corneal surface irregularity could be detected in severe dry eye patients with lacrimal punctal plugs in the short-term follow-up.     

Repeat keratoplasty for correction of high or irregular postkeratoplasty astigmatism in clear corneal grafts

PURPOSE: To evaluate the functional results of repeat penetrating keratoplasty in clear corneal grafts with high/irregular postkeratoplasty astigmatism. DESIGN: Retrospective, longitudinal, single-center, consecutive clinical case series. METHODS: We studied 17 eyes (16 keratoconus, 1 Fuchs' dystrophy) of 16 patients (age, 54.9 +/- 12.6 years). They were treated with repeat PK, performed using the 193-nm Zeiss-Meditec MEL-60 excimer laser using round metal masks (diameter, 7.5-8.0 mm), and employing double running sutures. main outcome measures: Subjective refractometry, standard keratometry, and corneal topography (Tomey TMS-1) were used to assess best-corrected visual acuity (BCVA), spherical equivalent (SEQ), keratometric and topographic central corneal power (CP), refractive, keratometric and topographic astigmatism, surface regularity index (SRI), surface asymmetry index (SAI), and potential visual acuity (PVA) preoperatively, before and after first suture removal (1.1 year), and after second suture removal (1.8 years). RESULTS: Visual acuity improved significantly (BCVA from 0.2-0.5, P = .04 or better) for all postoperative measurements. CP decreased significantly, but SEQ did not change. All measures of astigmatism and SRI and SAI values showed postoperative improvement with sutures in place; however, astigmatism increased significantly after second suture removal. CONCLUSIONS: With all-sutures-in, BCVA and astigmatism improve significantly after repeat PK for high/irregular astigmatism. However, to present significant increase in astigmatism, final suture removal should be postponed as long as possible in such eyes.     

Corneal topographic results after eccentric,biconvex penetrating keratoplasty

PURPOSE: To study the surgical outcomes and postoperative corneal topographies in 5 patients who had eccentric, biconvex penetrating keratoplasty (PKP) for peripheral corneal disorders whose extent did not allow the use of round grafts without involving the center of the cornea. SETTING: 1st Department of Ophthalmology, Semmelweis University, Medical School, Budapest, Hungary. METHODS: Eccentric, biconvex PKP that spared the optical axis of the cornea was performed in 5 eyes. Indications for surgery were perforated peripheral ulcerative keratitis (n = 3), extensive infiltrated peripheral ulcerative keratitis with impending perforation (n = 1), and ulcerated corneal degeneration caused by an intracameral foreign body for 9 years (n = 1). Computer-assisted corneal topography was performed postoperatively. The follow-up ranged from 8 to 27 months. RESULTS: All grafts were tectonically effective. Postoperative corneal topography showed normal central corneal regularity in 4 cases (1 case, normal pattern with surface regularity index [SRI] and surface asymmetry index [SAI] within the normal range; 3 cases, normal surface regularity within the central area of the cornea but moderate or high central corneal asymmetry). One eye had irregular astigmatism with a high SRI and SAI. In the first 4 cases, the best spectacle-corrected visual acuity was 0.8 (20/25) or better. CONCLUSIONS: The results show that eccentric, biconvex PKP sparing the central cornea may be an option in some eyes with perforated peripheral corneal disorders. Postoperative visual acuity may be good as the procedure may result in a regular central anterior corneal surface.     

Long-term functional and topographic results seven years after epikeratophakia for keratoconus

PURPOSE: To analyze the long-term effect of epikeratophakia (EKP) on corneal topography and visual acuity of eyes with keratoconus. METHODS: Retrospective study of 36 eyes 7.2 years after EKP. Four eyes underwent penetrating keratoplasty (PKP) and were excluded from further evaluation. Best-corrected visual acuity (BCVA) values were obtained from 32 eyes, corneal refraction and astigmatism from 23 eyes, surface asymmetry index (SAI) and surface regularity index (SRI) from 17 consecutive eyes that were operated upon after 1991, when the Tomey Topographic Modeling System became available. RESULTS: Only four eyes needed PKP. In addition to EKP six eyes had compression sutures and/or relaxing incisions, and one eye underwent photorefractive keratectomy. Mean refractive power of the cornea decreased from 51.8 to 45.8 and astigmatism from 7.2 to 3.8. SAI improved from 3.2 to 0.9 and SRI from 3.7 to 0.9. Mean BCVA was 0.3 preoperatively and 0.6 upon last follow-up. CONCLUSIONS: EKP was able to render PKP unnecessary in 32 of 36 eyes during the entire observation period. It was successful in permanently flattening the ectatic cornea and reducing astigmatism while restoring a symmetrical and smooth corneal surface. As a result, visual acuity improved considerably. In view of the young age of keratoconus patients needing surgery, and the fact that the lifetime of full-thickness corneal grafts is limited, EKP should be considered a valuable alternative to PKP in contact-lens-intolerant cases of keratoconus without central scarring.     

Effect of pterygium surgery on corneal topography: a prospective study

OBJECTIVE: To evaluate the effect of pterygium surgery on the corneal topography and visual acuity and to correlate the results with patients' features. METHODS: A prospective, nonrandomized, self-controlled trial. Computerized videokeratography was performed in 54 patients (55 eyes) with primary pterygium before and after pterygium excision using bare sclera technique combined with intraoperative mitomycin C. The following topographic parameters were noted: corneal astigmatism at the central 3 mm; total mean refractive power of the whole cornea; surface regularity index (SRI); and surface asymmetry index (SAI). Best corrected visual acuity of the operated eyes was also examined. Differences between pre- and postoperative values were evaluated statistically with paired two-tailed t test and two-tailed Pearson correlation. RESULTS: The respective values (mean +/- SD) before and after treatment of the study parameters were as follows: simulated keratometric astigmatism at 3 mm, 3.12 +/- 2.43 and 2.51 +/- 2.50 (P = 0.05); mean SRI, 0.99 +/- 0.65 and 0.90 +/- 0.65 (NS); mean SAI, 1.37 +/- 1.69 and 1.23 +/- 1.49 (NS). Best corrected visual acuity was 20/40 preoperatively and 20/25 postoperatively (P < 0.01). Both pre- and postoperative astigmatism correlated with pterygium size. CONCLUSIONS: Pterygium surgery significantly reduces refractive astigmatism and improves SRI, SAI, and best corrected visual acuity.